WorldWideScience

Sample records for ball bearings

  1. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  2. Ceramic Rail-Race Ball Bearings

    Science.gov (United States)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  3. Intelligent monitoring of ball bearing conditions

    Science.gov (United States)

    Liu, T. I.; Mengel, J. M.

    1992-09-01

    Ball bearings are widely used in various kinds of robots, manufacturing machines, and equipment. In order to enhance productivity and improve product quality, an on-line monitoring system is essential to check the status of ball bearings. In this work, peak amplitude in the frequency domain, peak RMS, and the power spectrum were used as indirect indices to develop a system for monitoring and classifying ball bearing defects. These indices were then processed by artificial neural networks. Six different cases of ball bearing states were observed. The data from these observations were then input into neural networks with different architectures to train these neural networks in a learning process. All the trained neural networks are capable of distinguishing the normal bearings from defective bearings with a 100 percent success rate. They can also classify the bearing conditions into six different states with a success rate of up to 97 per cent. The effects of training set sizes and neural network structures on the monitoring performance have also been investigated.

  4. Ball Bearing Analysis with the ORBIS Tool

    Science.gov (United States)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  5. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  6. Low-Wear Ball-Bearing Separator

    Science.gov (United States)

    Hawkinson, Elden L.

    1991-01-01

    Proposed ball-bearing separator for use in cryogenic pump stronger and more resistant to wear. Consists of molded plastic-and-metal composite ring imbued with solid lubricant and containing embedded metal ring. Obtains combination of strength and lubricity. Before molding and machining, ring includes tooling portion for handling and indexing. Molded composite blend of PTFE and fluorinated ethylene/propylene (FEP) filled with brass and bronze powder and molybdenum disulfide powder.

  7. Hardening treatment of friction surfaces of ball journal bearings

    Science.gov (United States)

    Gorlenko, A. O.; Davidov, S. V.

    2016-04-01

    The article presents the technology of finishing plasma hardening by the application of the multi-layer nanocoating Si-O-C-N system to harden the friction surfaces of the ball journal bearings. The authors of the paper have studied the applied wear-resistant anti-friction coating tribological characteristics, which determine the increase in wear resistance of the ball journal bearings.

  8. Nonlinear dynamic behaviors of ball bearing rotor system

    Institute of Scientific and Technical Information of China (English)

    WANG Li-qin; CUI Li; ZHENG De-zhi; GU Le

    2009-01-01

    Nonlinear forces and moments caused by ball bearing were calculated based on relationship of displacement and deflection and quasi-dynamic model of bearing. Five-DOF dynamic equations of rotor supported by ball bearings were estimated. The Newmark-β method and Newton-Laphson method were used to solve the equations. The dynamic characteristics of rotor system were studied through the time response, the phase portrait, the Poincar? maps and the bifurcation diagrams. The results show that the system goes through the quasiperiodic bifurcation route to chaos as rotate speed increases and there are several quasi-periodic regions and chaos regions. The amplitude decreases and the dynamic behaviors change as the axial load of ball bearing increases; the initial contact angle of ball bearing affects dynamic behaviors of the system obviously. The system can avoid non-periodic vibration by choosing structural parameters and operating parameters reasonably.

  9. Stiffness calculation and application of spline-ball bearing

    Science.gov (United States)

    Gu, Bo-Zhong; Zhou, Yu-Ming; Yang, De-Hua

    2006-12-01

    Spline-ball bearing is widely adopted in large precision instruments because of its distinctive performance. For the sake of carrying out detail investigation of a full instrument system, practical stiffness formulae of such bearing are introduced with elastic contact mechanics, which are successfully applied for calculating the stiffness of the bearing used in astronomical telescope. Appropriate treatment of the stiffness of such bearing in the finite element analysis is also discussed and illustrated.

  10. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    OpenAIRE

    Andrzej RACZYŃSKI; Jarosław KACZOR

    2014-01-01

    Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  11. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    Directory of Open Access Journals (Sweden)

    Andrzej RACZYŃSKI

    2014-06-01

    Full Text Available Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  12. EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

    Directory of Open Access Journals (Sweden)

    Jarosław KACZOR

    2014-06-01

    Full Text Available Durability deep groove ball bearings depends on factors (called attributes design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bearings to work three-bearing shafts, including elasticity and resilience three-bearing shafts.

  13. Ion implantation of silicon nitride ball bearings

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.M. [Oak Ridge National Lab., TN (United States); Miner, J.R. [United Technologies, Pratt and Whitney, West Palm Beach, FL (United States)

    1996-09-01

    Hypothesis for ion implantation effect was that stress concentrations reflected into the bulk due to topography such as polishing imperfections, texture in the race, or transferred material, might be reduced due to surface amorphization. 42 control samples were tested to an intended runout period of 60 h. Six ion implanted balls were tested to an extended period of 150 h. Accelerated testing was done in a V groove so that wear was on two narrow wear tracks. Rutherford backscattering, XRPS, profilometry, optical microscopy, nanoindentation hardness, and white light interferometry were used. The balls were implanted with 150-keV C ions at fluence 1.1x10{sup 17}/cm{sup 2}. The samples had preexisting surface defects (C-cracks), so the failure rate of the control group was unacceptable. None of the ion-implanted samples failed in 150 h of testing. Probability of randomly selecting 6 samples from the control group that would perform this well is about 5%, so there is good probability that ion implantation improved performance. Possible reasons are discussed. Wear tracks, microstructure, and impurity content were studied in possible relation to C-cracks.

  14. Extended Life Testing of Duplex Ball Bearings

    Science.gov (United States)

    Mobley, Jeffrey; Robertson, Michael; Hodges, Charles

    2016-01-01

    Sierra Nevada Corporation’s Space Systems performed bearing life testing for the Scan Mirror Motor/Encoder Assembly (SMMA), part of the Scan Mirror Assembly on-board the Aerosol Polarimetry Sensor (APS) on the NASA Glory Spacecraft. The baseline bearing life test duration extended beyond the launch date for the Glory Spacecraft; a risk that the program was willing to undertake with the understanding that if any anomalies or failures occurred before the required life was achieved, then the mission objectives or operating profile could be modified on orbit to take those results into account. Even though the Glory Spacecraft failed to reach orbit during its launch in March of 2011, the bearing life testing was continued through a mutual understanding of value between Sierra Nevada Corporation and our customer; with a revised goal of testing to failure rather than completing a required number of life cycles. Life testing thus far has not only exceeded the original mission required life, but has also exceeded the published test data for Cumulative Degradation Factor (CDF) from NASA/CR-2009-215681. Many lessons were learned along the way regarding long life testing. The bearing life test has been temporarily suspended due to test support equipment issues.

  15. Interference-Fit Life Factors for Ball Bearings

    Science.gov (United States)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2010-01-01

    The effect of hoop stresses on the rolling-element fatigue life of angular-contact and deep-groove ball bearings was determined for common inner-ring interference fits at the ABEC-5 tolerance level. The analysis was applied to over 1150 bearing configurations and load cases. Hoop stresses were superimposed on the Hertzian principal stresses created by the applied bearing load to calculate the inner-race maximum shearing stress. The resulting fatigue life of the bearing was recalculated through a series of equations. The reduction in the fatigue life is presented as life factors that are applied to the unfactored bearing life. The life factors found in this study ranged from 1.00 (no life reduction)--where there was no net interface pressure--to a worst case of 0.38 (a 62-percent life reduction). For a given interference fit, the reduction in life is different for angular-contact and deep-groove ball bearings. Interference fits also affect the maximum Hertz stress-life relation. Experimental data of Czyzewski, showing the effect of interference fit on rolling-element fatigue life, were reanalyzed to determine the shear stress-life exponent. The Czyzewski data shear stress-life exponent c equals 8.77, compared with the assumed value of 9. Results are presented as tables and charts of life factors for angular-contact and deep-groove ball bearings with light, normal, and heavy loads and interference fits ranging from extremely light to extremely heavy.

  16. EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

    OpenAIRE

    Jarosław KACZOR

    2014-01-01

    Durability deep groove ball bearings depends on factors (called attributes) design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bea...

  17. Analysis of grease contamination influence on the internal radial clearance of ball bearings by thermographic inspection

    OpenAIRE

    Mišković Žarko Z.; Mitrović Radivoje M.; Stamenić Zoran V.

    2016-01-01

    One of the most important factors influencing ball bearings service life is its internal radial clearance. However, this parameter is also very complex because it depends on applied radial load and ball bearings dimensions, surface finish and manufacturing materials. Thermal condition of ball bearings also significantly affects internal radial clearance. Despite many researches performed in order to find out relevant facts about different aspects of ball be...

  18. Performance of hybrid ball bearings in oil and jet fuel

    Science.gov (United States)

    Schrader, Stephen M.; Pfaffenberger, Eugene E.

    1992-07-01

    A 308-size hybrid ball bearing, with ceramic balls and steel rings, was tested using a diester oil and gas turbine fuel as lubricants at several speeds and loads. Heat generation data from this test work was then correlated with the heat generation model from a widely used computer code. The ability of this hybrid split inner ring bearing design to endure thrust reversals, which are expected in many turbine applications, was demonstrated. Finally, the bearing was successfully endurance tested in JP-10 fuel for 25 hours at 7560 N axial load and 36,000 rpm. This work has successfully demonstrated the technology necessary to use fuel-lubricated hybrid bearings in limited-life gas turbine engine applications such as missiles, drones, and other unmanned air vehicles (UAVs). In addition, it has provided guidance for use in designing such bearing systems. As a result, the benefits of removing the conventional oil lubricant system, i.e., design simplification and reduced maintenance, can be realized.

  19. 76 FR 10335 - Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping Duty Changed...

    Science.gov (United States)

    2011-02-24

    ..., 75 FR 37759 (June 30, 2010). After analysis of the quantity and value of the sales of ball bearings... FR 20900 (May 15, 1989). On June 30, 2010, we initiated an administrative review of the order on ball... International Trade Administration Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping...

  20. 76 FR 798 - Ball Bearings From Japan and the United Kingdom

    Science.gov (United States)

    2011-01-06

    ... COMMISSION [Investigation Nos. 731-TA-394-A & 399-A (Second Review) (Fourth Remand)] Ball Bearings From Japan... antidumping duty order on ball bearings from Japan. For further information concerning the conduct of this... and remanded-in-part the Commission's determinations in Certain Bearings and Parts Thereof from...

  1. 48 CFR 252.225-7016 - Restriction on acquisition of ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... of ball and roller bearings. 252.225-7016 Section 252.225-7016 Federal Acquisition Regulations System... and roller bearings. As prescribed in 225.7009-5, use the following clause: Restriction on Acquisition of Ball and Roller Bearings (MAR 2006) (a) Definitions. As used in this clause' (1)...

  2. Dynamic Analysis of Rotor Systems Considering Ball Bearing Contact Mechanism

    International Nuclear Information System (INIS)

    We propose a finite element modeling method considering the ball bearing contact mechanism, and the developed method was verified through experimental and analytical results of inner and outer race-type rotor systems. A comparison of the proposed method with conventional method reveals that there is little difference in the results of the inner race-type rotor system, but there are considerable differences in the results of the outer race-type rotor system such that predictions of greater accuracy can be made. Therefore, the proposed method can be used for accurately predicting the dynamic characteristics of an outer race-type rotary machine

  3. Using Adequate Ball Bearings in RC Car Chassis

    Directory of Open Access Journals (Sweden)

    Lucian Fridrik

    2011-06-01

    Full Text Available The paper presents the usage and misusage of ball bearings in rc car chassis technology of today . As this area is under massive development and could have a great impact in real cars it is important for new researchers to understand the importance of using the correct parts in constructing new devices and technologies based on the current one. As problems in economy are increasing it is important for new discovery’s to be tested in small scale models rather than full scale.

  4. 48 CFR 225.7009 - Restriction on ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Restriction on ball and roller bearings. 225.7009 Section 225.7009 Federal Acquisition Regulations System DEFENSE ACQUISITION... roller bearings....

  5. Acoustic measurement of lubricant-film thickness distribution in ball bearings

    OpenAIRE

    Zhang, J.; Drinkwater, B. W.; Dwyer-Joyce, R.S.

    2006-01-01

    An oil-film thickness monitoring system capable of providing an early warning of lubrication failure in rolling element bearings has been developed. The system is used to measure the lubricant-film thickness in a conventional deep groove ball bearing (shaft diameter 80 mm, ball diameter 12.7 mm). The measurement system comprises a 50 MHz broadband ultrasonic focused transducer mounted on the static outer raceway of the bearing. Typically the lubricant-films in rolling element bearings are bet...

  6. Analysis of grease contamination influence on the internal radial clearance of ball bearings by thermographic inspection

    Directory of Open Access Journals (Sweden)

    Mišković Žarko Z.

    2016-01-01

    Full Text Available One of the most important factors influencing ball bearings service life is its internal radial clearance. However, this parameter is also very complex because it depends on applied radial load and ball bearings dimensions, surface finish and manufacturing materials. Thermal condition of ball bearings also significantly affects internal radial clearance. Despite many researches performed in order to find out relevant facts about different aspects of ball bearings thermal behaviour, only few of them are dealing with the real working conditions, where high concentration of solid contaminant particles is present. That’s why the main goal of research presented in this paper was to establish statistically significant correlation between ball bearings temperatures, their working time and concentration of contaminant particles in their grease. Because of especially difficult working conditions, the typical conveyor idlers bearings were selected as representative test samples and appropriate solid particles from open pit coal mines were used as artificial contaminants. Applied experimental methodology included thermographic inspection, as well as usage of custom designed test rig for ball bearings service life testing. Finally, by obtained experimental data processing in advanced software, statistically significant mathematical correlation between mentioned bearings characteristics was determined and applied in commonly used internal radial clearance equation. That is the most important contribution of performed research - the new equation and methodology for ball bearings internal clearance determination which could be used for eventual improvement of existing bearings service life equations. [Projekat Ministarstva nauke Republike Srbije, br. TR35029 i br. TR14033

  7. 75 FR 76297 - Defense Federal Acquisition Regulation Supplement; Restriction on Ball and Roller Bearings (DFARS...

    Science.gov (United States)

    2010-12-08

    ... on May 7, 2010 (75 FR 25167). The comment period closed on July 6, 2010. Three respondents submitted... Regulation Supplement; Restriction on Ball and Roller Bearings (DFARS Case 2006-D029) AGENCY: Defense... source restriction on acquisition of ball and roller bearings. This final rule, which implements the...

  8. 77 FR 33159 - Ball Bearings and Parts Thereof From France, Germany, and Italy: Preliminary Results of...

    Science.gov (United States)

    2012-06-05

    ... Department published the antidumping duty orders on ball bearings and parts thereof from France (54 FR 20902), Germany (54 FR 20900), and Italy (54 FR 20903) in the ] Federal Register. On June 28, 2011, in accordance..., 71 FR 12170, 12173 (March 9, 2006), unchanged in Ball Bearings and Parts Thereof From France, et...

  9. 77 FR 53844 - Ball Bearings and Parts Thereof From France and Italy: Rescission of Antidumping Duty...

    Science.gov (United States)

    2012-09-04

    ... Duty Administrative Reviews and Request for Revocations in Part, 77 FR 40565 (July 10, 2012... International Trade Administration Ball Bearings and Parts Thereof From France and Italy: Rescission of... (the Department) initiated administrative reviews of the antidumping duty orders on ball bearings...

  10. 75 FR 30856 - Ball Bearings From Japan and the United Kingdom

    Science.gov (United States)

    2010-06-02

    ... FR 68036 (Nov. 8, 2002). In accordance with sections 201.16(c) and 207.3 of the Commission's rules... COMMISSION [Investigation Nos. 731-TA-394-A & 399-A (Second Review) (Third Remand)] Ball Bearings From Japan... antidumping orders on ball bearings from Japan and the United Kingdom. For further information concerning...

  11. Performance of High-Speed Grease Lubricated Hybrid Ceramic Ball Bearing

    Institute of Scientific and Technical Information of China (English)

    李秀娟; 王黎钦; 古乐

    2004-01-01

    To simplify the lubricating system for high-speed bearings and improve its reliability, grease lubricated high-speed hybrid ceramic bearings were theoretically and experimentally researched.Bearings with an outer race of 62 mm and eleven 9.525-mm balls were investigated.Traction coefficient and flash temperature between the bearing races and the balls were calculated and the results show that the traction coefficient of Si3N4 hybrid ceramic bearings is 74% that of the steel AISI 440B ones at 30 000 r/min and 1750 N, and the flash temperature of the hybrid bearings is 49% that of steel ones.Simulating the high-speed bearing rotational conditions, the grease lubricated hybrid ceramic ball bearings were tested and the results show that the power consumption of hybrid ceramic bearing lubricated by grease D at 24 000 r/min and axial load 1750 N is 80% that of steel ones.

  12. Quantitative NDE thermography for fault diagnosis of ball bearings with micro-foreign substances

    International Nuclear Information System (INIS)

    In this study, a non-destructive evaluation (NDE) method is proposed for ball bearings contaminated with micro foreign substances, which were inserted into a ball bearing to create a defective specimen. The non-contact quantitative infrared thermographic technique was applied for NDE condition monitoring. Passive thermographic experiments were conducted to perform early fault diagnosis, for bearings operated at optimized torque status under a dynamic load condition. The temperature profiles for normal and defective specimens were quantitatively compared, and the thermographic data analyzed. Based on the NDE results, the temperature characteristics and abnormal fault detection of the ball bearing were quantitatively analyzed according to the rise in temperature.

  13. Analytical Analysis of the Influence of Angular Misalignment on Ball Bearings Life

    OpenAIRE

    Luis Miguel Corzo Rodríguez; Gonzalo González Rey

    2013-01-01

    Experiences in application of ball bearings have demonstrated that the influence of angular misalignment,radial clearance and curvature ratio has an influence on the durability of bearings. However, there isnot enough technical information about any methods that considers the effect of there threecharacteristics on the life span of ball bearings. As a solution to this problem a series of calculationswas put forward with the assistance of ISO Technical Specification 16281: 2008 to study the in...

  14. 76 FR 58768 - Ball Bearings and Parts Thereof From France, Germany, and Italy; Amended Final Results of...

    Science.gov (United States)

    2011-09-22

    ... Reviews, 76 FR 52937 (August 24, 2011) (Final Results). The period of review is May 1, 2009, through April... International Trade Administration Ball Bearings and Parts Thereof From France, Germany, and Italy; Amended... ball bearings and parts thereof from France, Germany, and Italy. See Ball Bearings and Parts...

  15. A ball-bearing structured triboelectric nanogenerator for nondestructive damage and rotating speed measurement

    Science.gov (United States)

    Li, Xiao Hui; Han, Chang Bao; Jiang, Tao; Zhang, Chi; Wang, Zhong Lin

    2016-02-01

    A ball-bearing structure based triboelectric nanogenerator (B-TENG) with interdigitative-electrodes was developed that can not only collect energy from rotational kinetic energy, but also serve as a self-powered and multifunctional sensor. The B-TENG relies on the rolling electrification between PTFE balls on Cu interdigitative-electrodes, which delivers an open-circuit voltage of ∼40 V and a short-circuit current of ∼1.2 μA at a rotating speed of 300 rpm for 4 mm PTFE balls. Using the output signals of B-TENG, a nondestructive detection for the damage of PTFE balls was realized without demounting the bearing. Besides, based on the periodic signals produced from B-TENG, the rotation speed of ball-bearing can be obtained according to the time difference between several cycles.

  16. Measurement of separator contact forces in ball bearings using a derotation prism

    Science.gov (United States)

    Nypan, L. J.

    1978-01-01

    A derotation prism was used to produce a stationary image of balls deflecting a portion of the separator. Ball to cage contact forces in a 110 mm bearing at speeds to 12,000 rpm were found to be 25 N (five lb) maximum. Inner race land contact force was found to vary up to 20 N (four lb).

  17. 76 FR 327 - Ball Bearings and Parts Thereof From France: Partial Rescission of Antidumping Duty...

    Science.gov (United States)

    2011-01-04

    ..., 75 FR 37759 (June 30, 2010). Rescission of Review in Part In accordance with 19 CFR 351.213(d)(1... International Trade Administration Ball Bearings and Parts Thereof From France: Partial Rescission of... (the Department) initiated an administrative review of the antidumping duty order on ball...

  18. Nonlinear dynamic model for skidding behavior of angular contact ball bearings

    Science.gov (United States)

    Han, Qinkai; Chu, Fulei

    2015-10-01

    A three-dimensional nonlinear dynamic model is proposed to predict the skidding behavior of angular contact ball bearings under combined load condition. The centrifugal and gyroscopic effects induced by ball rotation and revolution, Hertz contact between the ball and inner/outer races, discontinuous contact between the ball and cage and elastohydrodynamic lubrication are considered in the model. Through comparisons with the tested results of the reference, the dynamic model is verified. Based upon these, variations of ball slipping speed with time and space are discussed for the bearing under combined load condition. It is shown that radial load leads to the fluctuations in the slipping velocity of the ball contacting with inner/outer races, especially for the ball in load-decreasing regions. Adding the radial load would significantly increase the amplitude and range of slipping velocity, indicating that the skidding becomes more serious. As the ball still withstands contact load in the load-decreasing region, large slipping velocity would increase the temperature of both bearing and lubricant oil, intensify the wear and then might shorten the bearing service life. Therefore, the radial load should be considered carefully in the design and monitoring of rotating machinery.

  19. Effects of various treatments on the serviceability of water-immersed carbon-steel ball bearings

    International Nuclear Information System (INIS)

    Carbon-steel ball bearings employing various coatings, surface treatments, lubricants and ball and separator materials were tested under conditions simulating those in the NPD/Bruce type fuelling machine heads. The effects of the treatments on operating torques and wear and corrosion rates were studied. Sealed bearings lubricated with Dow FS 3451 (a fluorosilicone grease) gave the best performance in terms of these parameters. (author)

  20. Non-linear dynamics and contacts of an unbalanced flexible rotor supported on ball bearings

    OpenAIRE

    Sinou, Jean-Jacques

    2009-01-01

    This study deals with the non-linear dynamic response of a flexible rotor supported by ball bearings. The excitation is due to unbalance force. The finite element rotor system is composed of a shaft with one disk, two flexible bearing supports and a ball bearing element where the non-linearities are due to both the radial clearance and the Herztian contact between races and rolling elements. A numerical analysis is performed to analyze the non-linear behavior of this bearing rotor by using th...

  1. Air flow patterns and noise analysis inside high speed angular contact ball bearings

    Institute of Scientific and Technical Information of China (English)

    翟强; 闫柯; 张优云; 朱永生; 王亚泰

    2015-01-01

    The vortex formed around the rolling ball and the high pressure region formed around the ball−raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil−air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil−air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

  2. Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings

    Science.gov (United States)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2012-01-01

    The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

  3. 75 FR 62763 - Ball Bearings and Parts Thereof From Germany: Amended Final Results of Antidumping Duty...

    Science.gov (United States)

    2010-10-13

    ... Reviews and Rescission of Reviews in Part, 73 FR 52823 (September 11, 2008). SKF USA Inc., SKF France S.A... International Trade Administration Ball Bearings and Parts Thereof From Germany: Amended Final Results of... bearings and parts thereof from Germany. See SKF USA Inc. v. United States, Slip Op. 10-76 (CIT 2010)....

  4. Research on the Critical Speed of a Mixed-Flow Turbocharger with Hybrid Ceramic Ball Bearing

    Institute of Scientific and Technical Information of China (English)

    HUANG Ruo; GE Xin-bin; MA Chao-chen

    2009-01-01

    The critical speeds for a vehicle turbocharger with hybrid ceramic ball bearing are researched. The ball bearing-rotor system produces resonance when it working in critical speed and that makes the turbocharger injury working for a long time. The calculation and analysis methods of the critical speed for the vehicle turbocharger are described. The critical speed is computed by two methods including Riccati transfer matrix and DyRoBeS finite element method for a vehicle turbocharger with hybrid ceramic ball bearing. The vibration experiment had been taken to validate the calculating result. Comparison between the results by two calculation methods and the test results show that the first critical speed differences are 6.47% and 5.66%, the second critical speed differences are 2.87% and 2.94% respectively. And then, the primary factors which influence the critical speed are analyzed, the conclusions will be helpful for the vehicle turbocharger bearing-rotor system design.

  5. On diagnosis measurement under dynamic loading of ball bearing using numerical thermal analysis and infrared thermography

    International Nuclear Information System (INIS)

    With the modern machinery towards the direction of high-speed development, the thermal issues of mechanical transmission system and its components is increasingly important. Ball bearing is one of the main parts in rotating machinery system, and is a more easily damaged part. In this paper, bearing thermal fault detection is investigated in details Using infrared thermal imaging technology to the operation state of the ball bearing, a preliminary thermal analysis, and the use of numerical simulation technology by finite element method(FEM) under thermal conditions of the bearing temperature field analysis, initially identified through these two technical analysis, bearing a temperature distribution in the normal state and failure state. It also shows the reliability of the infrared thermal imaging technology with valuable suggestions for the future bearing fault detection.

  6. Dynamic behaviour of ball bearing applications with constrained damping layers

    OpenAIRE

    Tillema, Hetzer G.

    2001-01-01

    Rolling bearing noise has become an aspect of increasing importance for the performance of rotating machinery, like electric motors and gearboxes. Generally, two aspects are important with regard to bearing noise, i.e. the transmission characteristics and the vibration generation characteristics. A potential source of vibrations are for example manufacturing imperfections of the different bearing components. Damping of bearing vibrations is enhanced by the lubrication film between the rolling...

  7. Experimental Study for Vibration Behaviors of Locally Defective Deep Groove Ball Bearings under Dynamic Radial Load

    OpenAIRE

    Patel, V. N.; Tandon, N.; Pandey, R. K.

    2014-01-01

    Rolling element bearings are used in many mechanical systems at the revolute joints for sustaining the dynamic loads. Thus, the reliable and efficient functioning of such systems critically depends on the good health of the employed rolling bearings. Hence, health monitoring of rolling bearings through their vibration responses is a vital issue. In this paper, an experimental investigation has been reported related to the vibration behaviours of healthy and locally defective deep groove ball ...

  8. Stiffness matrix formulation for double row angular contact ball bearings: Analytical development and validation

    Science.gov (United States)

    Gunduz, Aydin; Singh, Rajendra

    2013-10-01

    Though double row angular contact ball bearings are widely used in industrial, automotive, and aircraft applications, the scientific literature on double row bearings is sparse. It is also shown that the stiffness matrices of two single row bearings may not be simply superposed to obtain the stiffness matrix of a double row bearing. To overcome the deficiency in the literature, a new, comprehensive, analytical approach is proposed based on the Hertzian theory for back-to-back, face-to-face, and tandem arrangements. The elements of the five-dimensional stiffness matrix for double row angular contact ball bearings are computed given either the mean bearing displacement or the mean load vector. The diagonal elements of the proposed stiffness matrix are verified with a commercial code for all arrangements under three loading scenarios. Some changes in stiffness coefficients are investigated by varying critical kinematic and geometric parameters to provide more insight. Finally, the calculated natural frequencies of a shaft-bearing experiment are successfully compared with measurements, thus validating the proposed stiffness formulation. For double row angular contact ball bearings, the moment stiffness and cross-coupling stiffness terms are significant, and the contact angle changes under loads. The proposed formulation is also valid for paired (duplex) bearings which behave as an integrated double row unit when the surrounding structural elements are sufficiently rigid.

  9. 78 FR 76104 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Notice of Reinstatement of...

    Science.gov (United States)

    2013-12-16

    ... Roller Bearings, and Spherical Plain Bearings, and Parts Thereof From Japan, 54 FR 20904 (May 15, 1989... Value: Ball Bearings, and Cylindrical Roller Bearings and Parts Thereof From the United Kingdom, 54 FR... Initiation of Five-year (``Sunset'') Reviews, 70 FR 31423 (June 1, 2005), and Certain Bearings From...

  10. Experimental studies on vibration characteristics on ball bearing operated with copper oxide nano particle mixed lubricant

    Directory of Open Access Journals (Sweden)

    Prakash E

    2013-10-01

    Full Text Available The purpose of this paper is to investigate the vibration suppression characteristics of ball bearing supplied with nano-copper oxide (CuO mixed lubricant. CuO nanoparticles were synthesized by chemical method and characterized using XRD and TEM to study the crystallanity and ultrastructure. The synthesized CuO nanoparticles were of the size range 5-8 nm. 0.2%, 0.5%, and 1% (W/V of CuO nanoparticles was added to the lubricant (ISO VG 68 and was used for further analysis. The test rig setup consists of a ball bearing and loading arrangement operated by a DC motor. The bearing (New, Ball defect and Outer defect vibrations were measured using base lubricant and CuO lubricant mixture.Our results show a reduction of 41% vibration amplitude while using 0.2% (W/V CuO nanoparticles inouter case defected compared to base lubricant.

  11. Unbalance Response Prediction for Rotors on Ball Bearings Using Speed- and Load-Dependent Nonlinear Bearing Stiffness

    Directory of Open Access Journals (Sweden)

    Fleming David P.

    2005-01-01

    Full Text Available Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus, an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work, bearing forces were calculated by COBRA-AHS, a recently developed rolling-element bearing analysis code. Bearing stiffness was found to be a strong function of bearing deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the bearing data for a range of speeds and loads were supplied to a flexible rotor unbalance response analysis. The rotordynamic analysis showed that vibration response varied nonlinearly with the amount of rotor imbalance. Moreover, the increase in stiffness as critical speeds were approached caused a large increase in rotor and bearing vibration amplitude over part of the speed range compared to the case of constant-stiffness bearings. Regions of bistable operation were possible, in which the amplitude at a given speed was much larger during rotor acceleration than during deceleration. A moderate amount of damping will eliminate the bistable region, but this damping is not inherent in ball bearings.

  12. Dynamic behaviour of ball bearing applications with constrained damping layers

    NARCIS (Netherlands)

    Tillema, Hetzer G.

    2001-01-01

    Rolling bearing noise has become an aspect of increasing importance for the performance of rotating machinery, like electric motors and gearboxes. Generally, two aspects are important with regard to bearing noise, i.e. the transmission characteristics and the vibration generation characteristics. A

  13. Service life investigations of ball bearings at 1200C in a helium atmosphere

    International Nuclear Information System (INIS)

    The generally known rules for the layout of ball bearings do not yield in the case the bearings run in an helium atmosphere contaminated with impurities in the range of microbars. Therefore the layout of bearings put into action in helium has to be supported by tests carried out in a similar environment and for similar loads. With the aim to support the selection of lubricants and the design of the bearings in regard to the economical point of view, the basic principles of tribology in helium have been compiled and forty ball bearings have been tested at 900C and 1200C in helium. The applied loads comply with the usual values in machine construction. The tests show as result that ball bearings suitable for the different fields of applications in helium can be produced by simply exchanging the cages of standardized bearings. Reliable 107 revolutions have been obtained for different materials, also for cages made out of soft metals such as lead bronze, suitable in a radiation environment. In addition lubricants have been tested in order to find out the limits of suitability. (orig.)

  14. 76 FR 60871 - Ball Bearings and Parts Thereof From France, Germany, and Italy; Termination of Five-Year Reviews

    Science.gov (United States)

    2011-09-30

    ... deadline.'' (76 FR 57019). Accordingly, pursuant to section 751(c) of the Tariff Act of 1930 (19 U.S.C... COMMISSION Ball Bearings and Parts Thereof From France, Germany, and Italy; Termination of Five-Year Reviews... ball bearings and parts thereof from France, Germany, and Italy would be likely to lead to...

  15. 75 FR 41435 - Ball Bearings and Parts Thereof From Germany: Notice of Court Decision Not in Harmony With Final...

    Science.gov (United States)

    2010-07-16

    ... and Rescission of Reviews in Part, 73 FR 52823 (September 11, 2008). SKF USA Inc., SKF France S.A... International Trade Administration Ball Bearings and Parts Thereof From Germany: Notice of Court Decision Not in... the administrative review of the antidumping duty order on ball bearings and parts thereof...

  16. Comparison of tungsten carbide and stainless steel ball bearings for grinding single maize kernels in a reciprocating grinder

    Science.gov (United States)

    Reciprocating grinders can grind single maize kernels by shaking the kernel in a vial with a ball bearing. This process results in a grind quality that is not satisfactory for many experiments. Tungesten carbide ball bearings are nearly twice as dense as steel, so we compared their grinding performa...

  17. 76 FR 2647 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2011-01-14

    ... Revocation in Part, 75 FR 37759 (June 30, 2010). The preliminary results of the reviews are currently due no... International Trade Administration Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the...) initiated administrative reviews of the antidumping duty orders on ball bearings and parts thereof...

  18. A Study on the Effects of Ball Defects on the Fatigue Life in Hybrid Bearings

    Science.gov (United States)

    Tang, Ching-Yao; Foerster, Chad E.; O'Brien, Michael J.; Hardy, Brian S.; Goyal, Vinay K.; Nelson, Benjamin A.; Robinson, Ernest Y.; Ward, Peter C.; Hilton, Michael R.

    2014-01-01

    Hybrid ball bearings using silicon nitride ceramic balls with steel rings are increasingly being used in space mechanism applications due to their high wear resistance and long rolling contact fatigue life. However, qualitative and quantitative reports of the effects of ball defects that cause early fatigue failure are rare. We report on our approach to study these effects. Our strategy includes characterization of defects encountered in use, generation of similar defects in a laboratory setting, execution of full-scale bearing tests to obtain lifetimes, post-test characterization, and related finite-element modeling to understand the stress concentration of these defects. We have confirmed that at least one type of defect of appropriate size can significantly reduce fatigue life. Our method can be used to evaluate other defects as they occur or are encountered.

  19. Finite element analysis of deformation characteristics in cold helical rolling of bearing steel-balls

    Institute of Scientific and Technical Information of China (English)

    曹强; 华林; 钱东升

    2015-01-01

    Due to the complexity of investigating deformation mechanisms in helical rolling (HR) process with traditional analytical method, it is significant to develop a 3D finite element (FE) model of HR process. The key forming conditions of cold HR of bearing steel-balls were detailedly described. Then, by taking steel-ball rolling elements of the B7008C angular contact ball bearing as an example, a completed 3D elastic-plastic FE model of cold HR forming process was established under SIMUFACT software environment. Furthermore, the deformation characteristics in HR process were discovered, including the forming process, evolution and distribution laws of strain, stress and damage based on Lemaitre relative damage model. The results reveal that the central loosening and cavity defects in HR process may have a combined effect of large negative hydrostatic pressure (positive mean stress) caused by multi-dimensional tensile stresses, high level transverse tensile stress, and circular-alternating shear stress in cross section.

  20. 76 FR 22372 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2011-04-21

    ... antidumping duty orders on ball bearings and parts thereof from France (54 FR 20902), Germany (54 FR 20900... Bearings and Parts Thereof From France: Partial Rescission of Antidumping Duty Administrative Review, 76 FR... Value; Antifriction Bearings (Other Than Tapered Roller Bearings) and Parts Thereof From Japan, 54...

  1. DETERMINING THE REACTIONS OF BALLS SLEWING BEARING MOUNTED IN WORKING STRUCTURES OF THE SINGLE-BUCKET EXCAVATOR

    Directory of Open Access Journals (Sweden)

    Ludwik KANIA

    2014-06-01

    Full Text Available In the article the problem of modeling methodology slewing bearings by take into account partial or complete structures of housing in the working machine is presented. The structures of two exemplary models are described. The object of the study was single-bucket excavator caterpillar type F250H. Basic parameters of analyzed bearing are presented. The finite element method has been used to the modeling procedure. The calculation which is needed to calculate the force loading of balls slewing bearing has been done using the ADINA program. The way of calculating single-row ball slewing bearing rings which is presented in this paper, used the analytic correlation which determine the permissible load of contact zone (ball-bearing race in slewing bearings too. The chosen distributions of reactions loading on the balls are presented. The results are shown as a graph

  2. Calculation of flash temperature for hybrid ceramic ball bearing lubricated with solid

    Institute of Scientific and Technical Information of China (English)

    李秀娟; 王黎钦; 古乐; 齐毓霖

    2002-01-01

    The scuffing behavior of hybrid ceramic bearing lubricated with solid is greatly affected by the contact flash temperature. Formulas are dedused using Lee' s asperity flash temperature method, to calculate the flash temperature of ball bearing lubricated with solid. The maximum flash temperature is calculated for hybrid ceramic ball bearings. The results show that under given conditions, the flash temperature of inner race is higher than that of outer race, the flash temperature of the hybrid ceramic bearing is sensitive to the load, rotational speed and race curvature. The flash temperature of inner race at 20 000 r/min is 66.9% more than that that at 11 000 r/min, and with the load changing from 1.1 kN to 2 kN, the flash temperature inner race goes up to 165.7%. Very common for high speed ball bearings, when curvature coefficients of both inner and outer race change from 0. 515 to 0.56, the inner race flash temperature decreases from 421. 446℃ to 56.2℃.

  3. DYNAMICS AND FAULT DETECTION IN ROTOR BALL BEARING SYSTEM

    OpenAIRE

    Nilambari Shinde; D R . S. P. Shekhawat

    2015-01-01

    The dynamics of high speed rotating machinery plays an important role in the modern world. In the design of complex mechanical components and rotating machines, such as turbines, compressors , electrical machines, centrifuges or machine tool spindles, systematic analysis of dynamic behavior is needed. The dynamics of a rotor can be highly influenced by the design of support bearings, since, the critical speeds and the magnitude of v...

  4. Fatigue behaviour FEM modeling of deep groove ball bearing mounted in automotive alternator submitted to variable loading

    Directory of Open Access Journals (Sweden)

    Azianou Ayao. E.

    2014-06-01

    Full Text Available Ball bearings subsurface materials are subjected to rolling contact fatigue with multiaxial stress state during loading cycle. The complex operating conditions of automotive bearings are different from classic operating conditions their fatigue crack initiation predicted by standards can be seen underestimated. This work presents a numerical approach of ball bearings to evaluate its fatigue behaviour in order to predict the life. A preliminary study has been done to evaluate the load distribution in the bearings. The results are integrated in a numerical dynamic model to study the bearing material rolling fatigue behaviour in constant and variable loading cases. By using fatigue criteria and damage laws, the analysis of stress state in bearing material leads to life prediction or the number of cycles before crack initiations. These results are compared to current standard methods used for ball bearing life prediction.

  5. 75 FR 26920 - Ball Bearings and Parts Thereof from France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2010-05-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Ball Bearings and Parts Thereof from France, Germany, Italy, Japan, and the United Kingdom: Preliminary Results of Antidumping Duty Administrative Reviews, Preliminary Results...

  6. Toward a 3D dynamic model of a faulty duplex ball bearing

    Science.gov (United States)

    Kogan, Gideon; Klein, Renata; Kushnirsky, Alex; Bortman, Jacob

    2015-03-01

    Bearings are vital components for safe and proper operation of machinery. Increasing efficiency of bearing diagnostics usually requires training of health and usage monitoring systems via expensive and time-consuming ground calibration tests. The main goal of this research, therefore, is to improve bearing dynamics modeling tools in order to reduce the time and budget needed to implement the health and usage monitoring approach. The proposed three-dimensional ball bearing dynamic model is based on the classic dynamic and kinematic equations. Interactions between the bodies are simulated using non-linear springs combined with dampers described by Hertz-type contact relation. The force friction is simulated using the hyperbolic-tangent function. The model allows simulation of a wide range of mechanical faults. It is validated by comparison to known bearing behavior and to experimental results. The model results are verified by demonstrating numerical convergence. The model results for the two cases of single and duplex angular ball bearings with axial deformation in the outer ring are presented. The qualitative investigation provides insight into bearing dynamics, the sensitivity study generalizes the qualitative findings for similar cases, and the comparison to the test results validates model reliability. The article demonstrates the variety of the cases that the 3D bearing model can simulate and the findings to which it may lead. The research allowed the identification of new patterns generated by single and duplex bearings with axially deformed outer race. It also enlightened the difference between single and duplex bearing manifestation. In the current research the dynamic model enabled better understanding of the physical behavior of the faulted bearings. Therefore, it is expected that the modeling approach has the potential to simplify and improve the development process of diagnostic algorithms. • A deformed outer race of a single axially loaded bearing is

  7. Research and Development of a Chaotic Signal Synchronization Error Dynamics-Based Ball Bearing Fault Diagnostor

    Directory of Open Access Journals (Sweden)

    Ying-Che Kuo

    2014-10-01

    Full Text Available This paper describes the fault diagnosis in the operation of industrial ball bearings. In order to cluster the very small differential signals of the four classic fault types of the ball bearing system, the chaos synchronization (CS concept is used in this study as the chaos system is very sensitive to a system’s variation such as initial conditions or system parameters. In this study, the Chen-Lee chaotic system was used to load the normal and fault signals of the bearings into the chaos synchronization error dynamics system. The fractal theory was applied to determine the fractal dimension and lacunarity from the CS error dynamics. Extenics theory was then applied to distinguish the state of the bearing faults. This study also compared the proposed method with discrete Fourier transform and wavelet packet analysis. According to the results, it is shown that the proposed chaos synchronization method combined with extenics theory can separate the characteristics (fractal dimension vs. lacunarity completely. Therefore, it has a better fault diagnosis rate than the two traditional signal processing methods, i.e., Fourier transform and wavelet packet analysis combined with extenics theory.

  8. Chaotic Dynamics of High Speed Rotating Shaft Supported by Ball Bearings Due to Distributed Defects

    Directory of Open Access Journals (Sweden)

    S. H. Upadhyay ,

    2010-10-01

    Full Text Available This paper presents a mathematical model to investigate the nonlinear dynamic behavior of a high speed rotorbearing system due to varying the number of rolling elements. Two cases one without race defect and one with defect as race waviness have been studied. In the formulation, the contacts between rolling elements and inner/outerraces are considered as nonlinear springs and also used nonlinear damping, which is developed by correlating the contact damping force with the equivalent contact stiffness and contact deformation rate. The equations of motion are formulated using Lagrange’s equation, considering the vibration characteristics of the individual componentssuch as inner race, outer race, rolling elements and rotor. For non-defective bearings, nonlinear dynamic responses are found to be associated with ball passage frequency ( bp  . For defective bearings, nonlinear dynamic responses are found to be associated mainly with wave passage frequency ( wp  and also with the interactive effect of wave passage and ball passage frequencies. The wave-number (Nw of waviness and number of balls (Nb are importantparameters of study because even if these are inevitable, these can be controlled the system nature to a good extent.

  9. Experimental Analysis of Damping and Tribological Characteristics of Nano-CuO Particle Mixed Lubricant in Ball Bearings

    Science.gov (United States)

    Prakash, E.; Sivakumar, K.

    2015-12-01

    Experimental analysis of damping capacity and tribological characteristics of nano CuO added Servosystem 68 lubricant is attempted. CuO nano particles were synthesized by aqueous precipitation method and characterized. Prior to dispersion into lubricant, CuO nano particles were coated with 0.2 wt.% surfactant (Span-80) to stabilize the nano fluid. Tribological characteristics of particle added lubricant were tested in ASTM D 4172 four ball wear tester. Scanning electron microscopy test results of worn surfaces of nano CuO particle added lubricant were smoother than base lubricant. The particle added lubricant was applied in a new ball bearing and three defected ball bearings. When particle added lubricant was used, the ball defected bearing's vibration amplitude was reduced by 21.94% whereas it was 16.46% for new bearing and was ≤ 11% for other defected bearings. The formation of protection film of CuO over ball surface and regime of full film lubrication near the ball zone were observed to be reason for improved damping of vibrations.

  10. Optimization of the Chemical Composition of Cast Iron Used for Casting Ball Bearing Grinding Disks

    Institute of Scientific and Technical Information of China (English)

    Aurel Crisan; Sorin Ion; Munteanu; Ioan Ciobanu; Iulian Riposan

    2008-01-01

    The chemical composition of cast iron used for casting ball bearing machining disks was varied to optimize the properties such as castability, hardenability, and durability in ball machining. The cast iron characteristics were most strongly dependent on the Ni content and the carbon saturation degree, So. This paper describes the types of test specimens, the working conditions, and the experimental results. The in-crease of the degree of carbon saturation reduces the tendency to form shrinkholes in the castings. The de-crease in the Ni content negatively affects the final hardening treatment. A way to control solidification de-fects in cast iron, by reducing the Ni content, has been verified on cast disks.

  11. 77 FR 75973 - Ball Bearings and Parts Thereof From France, Germany, and Italy: Final Results of Antidumping...

    Science.gov (United States)

    2012-12-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Ball Bearings and Parts Thereof From France, Germany, and Italy: Final.... and WPB Water Pump Bearing GmbH & 0.00 Co. KG, Schaeffler Italia SpA and The Schaeffler Group......

  12. Vibration analysis of angular contact ball bearing operated with copper oxide nanoparticles mixed ISO VG 68 lubricating oil

    Directory of Open Access Journals (Sweden)

    Prakash E.

    2014-09-01

    Full Text Available The purpose of this paper is to investigate the effect of CuO nanoparticles on lubricating oil and vibration reduction in angular contact ball bearing. CuO nanoparticles are synthesized by using chemical method and characteristic studies done in XRD and TEM. CuO nanoparticles size achieved in the range 26 - 30 nm. The nanoparticles concentration of 0.2 wt. % added into the lubricant (ISO VG 68. The testrig setup consists of angular contact ball bearing operated by AC motor with speed controller. The bearing (New and outer defect vibrations measured using base oil and CuO mixed oil.

  13. Experimental studies on vibration characteristics on ball bearing operated with copper oxide nano particle mixed lubricant

    OpenAIRE

    Prakash E.; Siva Kumar K; Muthu Kumar K

    2013-01-01

    The purpose of this paper is to investigate the vibration suppression characteristics of ball bearing supplied with nano-copper oxide (CuO) mixed lubricant. CuO nanoparticles were synthesized by chemical method and characterized using XRD and TEM to study the crystallanity and ultrastructure. The synthesized CuO nanoparticles were of the size range 5-8 nm. 0.2%, 0.5%, and 1% (W/V) of CuO nanoparticles was added to the lubricant (ISO VG 68) and was used for further analysis. The test rig setup...

  14. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat treatment on nitrided layer

    Indian Academy of Sciences (India)

    Ravindra Kumar; J Alphonsa; Ram Prakash; K S Boob; J Ghanshyam; P A Rayjada; P M Raole; S Mukherjee

    2011-02-01

    In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific steel is that its tempering temperature (∼170–200°C) is much lower than the standard processing temperature (∼460–580°C) needed for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated. Experiments are performed on three different types of ball bearing races i.e. annealed, quenched and quench-tempered samples. Different gas compositions and process temperatures are maintained while nitriding these samples. In the quenched and quench-tempered samples, the surface hardness has decreased after plasma nitriding process. Plasma nitriding of annealed sample with argon and nitrogen gas mixture gives higher hardness in comparison to the hydrogen–nitrogen gas mixture. It is reported that the later heat treatment of the plasma nitrided annealed sample has shown improvement in the hardness of this steel. X-ray diffraction analysis shows that the dominant phases in the plasma nitrided annealed sample are (Fe2−3N) and (Fe4N), whereas in the plasma nitrided annealed sample with later heat treatment only -Fe peak occurs.

  15. SVD and Hankel matrix based de-noising approach for ball bearing fault detection and its assessment using artificial faults

    Science.gov (United States)

    Golafshan, Reza; Yuce Sanliturk, Kenan

    2016-03-01

    Ball bearings remain one of the most crucial components in industrial machines and due to their critical role, it is of great importance to monitor their conditions under operation. However, due to the background noise in acquired signals, it is not always possible to identify probable faults. This incapability in identifying the faults makes the de-noising process one of the most essential steps in the field of Condition Monitoring (CM) and fault detection. In the present study, Singular Value Decomposition (SVD) and Hankel matrix based de-noising process is successfully applied to the ball bearing time domain vibration signals as well as to their spectrums for the elimination of the background noise and the improvement the reliability of the fault detection process. The test cases conducted using experimental as well as the simulated vibration signals demonstrate the effectiveness of the proposed de-noising approach for the ball bearing fault detection.

  16. Vibration analysis of angular contact ball bearing operated with copper oxide nanoparticles mixed ISO VG 68 lubricating oil

    OpenAIRE

    Prakash E.; Sivakumar K

    2014-01-01

    The purpose of this paper is to investigate the effect of CuO nanoparticles on lubricating oil and vibration reduction in angular contact ball bearing. CuO nanoparticles are synthesized by using chemical method and characteristic studies done in XRD and TEM. CuO nanoparticles size achieved in the range 26 - 30 nm. The nanoparticles concentration of 0.2 wt. % added into the lubricant (ISO VG 68). The testrig setup consists of angular contact ball bearing operated by AC motor with speed control...

  17. Performance of integrated retainer rings in silicon micro-turbines with thrust style micro-ball bearings

    International Nuclear Information System (INIS)

    This work explores the performance of different silicon retainer ring designs when integrated into silicon micro-turbines (SMTs) incorporating thrust style bearings supported on 500 µm diameter steel balls. Experimental performance curves are presented for SMTs with rotor diameters of 5 mm and 10 mm, each with five different retainer designs varying in mechanical rigidity, ball pocket shape and ball complement. It was found that the different retainer designs yielded different performance curves, with the closed pocket designs consistently requiring lower input power for a given rotation speed, and the most rigid retainers giving the best performance overall. Both 5 mm and 10 mm diameter devices have shown repeatable performance at rotation speeds up to and exceeding 20 000 RPM with input power levels below 2 W, and devices were tested for over 2.5 million revolutions without failure. Retainer rings are commonly used in macro-scale bearings to ensure uniform spacing between the rolling elements. The integration of retainers into micro-bearings could lower costs by reducing the number of balls required for stable operation, and also open up the possibility of ‘smart’ bearings with integrated sensors to monitor the bearing status. (paper)

  18. A study of microstructures in laser melted ball-bearing and turbine blade steels

    International Nuclear Information System (INIS)

    Surface treatments of steels by high power lasers are known to result in high surface hardness and improved resistance to wear and fatigue failures. Thin surface regions of an off-grade AISI-SAE 52100 ball-bearing steel and 12CrMoV turbine blade steel were laser melted by pubed Nd:YAG and Nd:Glass lasers. Microstructural changes that resulted due to laser melting and subsequent rapid solidification were examined by an optical as well as a scanning electron microscope. Compositional variations in the recast regions were studied by using an electron probe microanalyser. Variations in hardness with depth from the laser treated surface were correlated with the observed microstructures. Also the role of Cr/C ratio on the development of these microstructures in the two steels was delineated. These results are discussed. (author). 22 refs., 9 figs., 1 tab

  19. 76 FR 15940 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2011-03-22

    ... United Kingdom: Extension of Time Limit for Preliminary Results of Antidumping Duty Administrative and... and parts thereof from ] France, Germany, Italy, Japan, and the United Kingdom for the period May 1... thereof from France, Germany, Italy, Japan, and the United Kingdom. See Ball Bearings and Parts...

  20. 75 FR 53661 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom: Final...

    Science.gov (United States)

    2010-09-01

    ... United Kingdom: Final Results of Antidumping Duty Administrative Reviews, Final Results of Changed... thereof from France, Germany, Italy, Japan, and the United Kingdom. The reviews cover 22 manufacturers... order on ball bearings and parts thereof from the United Kingdom in part with respect to...

  1. 76 FR 52937 - Ball Bearings and Parts Thereof From France, Germany, and Italy: Final Results of Antidumping...

    Science.gov (United States)

    2011-08-24

    ... Part of an Antidumping Duty Order, 58 FR 39729 (July 26, 1993). For ball bearings and parts thereof... Changed-Circumstances Reviews, 76 FR 22372 (April 21, 2011) (Preliminary Results).\\1\\ \\1\\ The Department... From Japan and the United Kingdom: Revocation of Antidumping Duty Orders, 76 FR 41761 (July 15,...

  2. 77 FR 16537 - Ball Bearings and Parts Thereof from France, Germany, and Italy: Extension of Time Limit for...

    Science.gov (United States)

    2012-03-21

    ... Revocation in Part, 76 FR 37781 (June 28, 2011). See also Ball Bearings and Parts Thereof From Japan and the United Kingdom: Revocation of Antidumping Duty Orders, 76 FR 41761 (July 15, 2011), where we revoked the... of Time Limit for Preliminary Results of Antidumping Duty Administrative Reviews, 77 FR 2511...

  3. 75 FR 69402 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2010-11-12

    ... Revocation in Part, 75 FR 37759 (June 30, 2010). Rescission of Reviews in Part In accordance with 19 CFR 351..., Final Results of Changed-Circumstances Review, and Revocation of an Order in Part, 75 FR 53661... International Trade Administration Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and...

  4. Failure Analysis and Recovery of a 50-mm Highly Elastic Intermetallic NiTi Ball Bearing for an ISS Application

    Science.gov (United States)

    DellaCorte, Christopher; Howard, S. Adam; Moore, Lewis

    2016-01-01

    Ball bearings used inside the ISS Distillation Assembly centrifuge require superior corrosion and shock resistance to withstand acidic wastewater exposure and heavy spacecraft launch related loads. These requirements challenge conventional steel bearings and provide an ideal pathfinder application for 50-mm bore, deep-groove ball bearings made from the corrosion immune and highly elastic intermetallic material 60NiTi. During early ground testing in 2014 one 60NiTi bearing unexpectedly and catastrophically failed after operating for only 200 hr. A second bearing running on the same shaft was completely unaffected. An investigation into the root cause of the failure determined that an excessively tight press fit of the bearing outer race coupled with NiTi's relatively low elastic modulus were key contributing factors. The proposed failure mode was successfully replicated by experiment. To further corroborate the root cause theory, a successful bearing life test using improved installation practices (selective fitting) was conducted. The results show that NiTi bearings are suitable for space applications provided that care is taken to accommodate their unique material characteristics.

  5. Time-Varying Total Stiffness Matrix of a Rigid Machine Spindle-Angular Contact Ball Bearings Assembly: Theory and Analytical/Experimental Verifications

    OpenAIRE

    Fawzi M.A. El-Saeidy

    2011-01-01

    A lagrangian formulation is presented for the total dynamic stiffness and damping matrices of a rigid rotor carrying noncentral rigid disk and supported on angular contact ball bearings (ACBBs). The bearing dynamic stiffness/damping marix is derived in terms of the bearing motions (displacements/rotations) and then the principal of virtual work is used to transfer it from the bearing location to the rotor mass center to obtain the total dynamic stiffness/damping matrix. The bearing analyses t...

  6. THE MODEL OF THE RADIAL-THRUST BALL BEARING FOR ANALYSIS OF NONLINEAR VIBRATIONS OF THE ROTOR

    Directory of Open Access Journals (Sweden)

    S. Filipkovskyi

    2015-12-01

    Full Text Available The non-linear model of resilient forces of pre-loaded ball bearing is developed. The contact forces are obtained and arranged in the Heyn’s row on the basis of Herts theory. The obtained model is used for solving the problem of non-linear dynamics of vehicles. The design samples correspond to calculations performed with the help of the traditional model.

  7. THE MODEL OF THE RADIAL-THRUST BALL BEARING FOR ANALYSIS OF NONLINEAR VIBRATIONS OF THE ROTOR

    OpenAIRE

    S. Filipkovskyi

    2015-01-01

    The non-linear model of resilient forces of pre-loaded ball bearing is developed. The contact forces are obtained and arranged in the Heyn’s row on the basis of Herts theory. The obtained model is used for solving the problem of non-linear dynamics of vehicles. The design samples correspond to calculations performed with the help of the traditional model.

  8. Superelastic Ball Bearings: Materials and Design to Avoid Mounting and Dismounting Brinell Damage in an Inaccessible Press-Fit Application-. I ; Design Approach

    Science.gov (United States)

    Dellacorte, Christopher; Howard, S. Adam

    2015-01-01

    Ball bearings require proper fit and installation into machinery structures (onto shafts and into bearing housings) to ensure optimal performance. For some applications, both the inner and outer race must be mounted with an interference fit and care must be taken during assembly and disassembly to avoid placing heavy static loads between the balls and races otherwise Brinell dent type damage can occur. In this paper, a highly dent resistant superelastic alloy, 60NiTi, is considered for rolling element bearing applications that encounter excessive static axial loading during assembly or disassembly. A small (R8) ball bearing is designed for an application in which access to the bearing races to apply disassembly tools is precluded. First Principles analyses show that by careful selection of materials, raceway curvature and land geometry, a bearing can be designed that allows blind assembly and disassembly without incurring raceway damage due to ball denting. Though such blind assembly applications are uncommon, the availability of bearings with unusually high static load capability may enable more such applications with additional benefits, especially for miniature bearings.

  9. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    OpenAIRE

    Gerrit eVoordouw; Priyesh eMenon; Tijan ePinnock; Mohita eSharma; Yin eShen; Amanda eVenturelli; Johanna eVoordouw; Aoife eSexton

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs ba...

  10. Technological Considerations and Constraints in the Manufacture of High Precision Ball and Roller Bearings

    Directory of Open Access Journals (Sweden)

    Prof.S.Rajendiran,

    2015-12-01

    Full Text Available Rolling element bearings for application in Aircraft systems are to be manufactured to higher accuracy levels. Various technology details like raw material, processing stages and facilities such as machining, heat treatment, grinding, super finishing, assembly and inspection are to be considered for manufacture. However the facilities available presently in India are inadequate to produce high precision bearings. This paper deals with the prototype manufacture of bearings for some typical applications.

  11. Vibration Analysis of deep groove ball bearing using Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Mr. Shaha Rohit D

    2015-05-01

    Full Text Available Rolling element bearing is essential part of machinery. The rolling bearing, with outer ring fixed, is a multi body mechanical system with rolling elements that transmit motion and load from the inner raceway to the outer raceway. The rolling bearings dynamical behaviour analysis is an important condition to determine the machine vibration response. Modern trend of Dynamic analysis is useful in early prediction. Dynamic analysis has become a very powerful tool for the betterment of the actual performance of the system. The methodology for prediction and validation of dynamic characteristics of bearing rotor system vibration is studied. ANSYS software is the promising tools for the modelling. The result obtained from FEA are validated with experimental results.

  12. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GigaPascals) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 millimeters diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  13. 75 FR 3444 - Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping Duty Changed...

    Science.gov (United States)

    2010-01-21

    ... Republic of Germany, 54 FR 20900 (May 15, 1989). The orders on cylindrical roller bearings and spherical... Kingdom, 65 FR 42667 (July 11, 2000). Miniaturkugellager GmbH (MKL) was a respondent in a new-shipper... Parts Thereof, From Germany; Final Results of New Shipper Antidumping Duty Administrative Review, 61...

  14. Superelastic Ball Bearings: Materials and Design to Avoid Mounting and Dismounting Brinell Damage in an Inaccessible Press-fit Application-. II; Detailed Analysis

    Science.gov (United States)

    Howard, S. Adam; Dellacorte, Christopher

    2015-01-01

    Rolling element bearings utilized in precision rotating machines require proper alignment, preload, and interference fits to ensure overall optimum performance. Hence, careful attention must be given to bearing installation and disassembly procedures to ensure the above conditions are met. Usually, machines are designed in such a way that bearings can be pressed into housings or onto shafts through the races without loading the rolling elements. However, in some instances, either due to limited size or access, a bearing must be installed or removed in such a way that the load path travels through the rolling elements. This can cause high contact stresses between the rolling elements and the races and introduces the potential for Brinell denting of the races. This paper is a companion to the Part I paper by the authors that discusses material selection and the general design philosophy for the bearing. Here, a more in-depth treatment is given to the design of a dent-resistant bearing utilizing a superelastic alloy, 60NiTi, for the races. A common bearing analysis tool based on rigid body dynamics is used in combination with finite element simulations to design the superelastic bearing. The primary design constraints are prevention of denting and avoiding the balls riding over the edge of the race groove during a blind disassembly process where the load passes through the rolling elements. Through an iterative process, the resulting bearing geometry is tailored to improve axial static load capability compared to a deep-groove ball bearing of the same size. The results suggest that careful selection of materials and bearing geometry can enable blind disassembly without damage to the raceways, which is necessary in the current application (a compressor in the International Space Station Environmental Control and Life Support System), and results in potential design flexibility for other applications, especially small machines with miniature bearings.

  15. Numerical study of the flow in a ball bearing cross-section; Etude numerique de l`ecoulement dans une coupe transversale de roulements a billes

    Energy Technology Data Exchange (ETDEWEB)

    Combes, J.F. [Electricite de France (EDF), 92 - Clamart (France). Direction des Etudes et Recherches; Bidot, T. [Simulog, (France)

    1997-01-01

    In the Ariane rocket propulsion system, ball bearings operate under very severe conditions; in order to evaluate heat transfers enabling their cooling, the flow inside the bearings themselves has to be determined. A numerical study has been carried out by Simulog company using the Turbomachinery release of the N3S code developed by Electricite de France. After a brief presentation of the fluid dynamics N3S code and its turbomachinery version, its application to the calculation of the flow within a ball bearing is presented: as it was shown in a preliminary study, the 3D flow can be split into a succession of 2D flows on parallel slices; therefore examples of laminar and turbulent flow calculation on a cross section are given. Comparison of flow structure calculations with experimental and analytical results is discussed

  16. Ultrasonic acoustic health monitoring of ball bearings using neural network pattern classification of power spectral density

    Science.gov (United States)

    Kirchner, William; Southward, Steve; Ahmadian, Mehdi

    2010-03-01

    This paper presents a generic passive non-contact based approach using ultrasonic acoustic emissions (UAE) to facilitate the neural network classification of bearing health, and more specifically the bearing operating condition. The acoustic emission signals used in this study are in the ultrasonic range (20-120 kHz). A direct benefit of microphones capable of measurements in this frequency range is their inherent directionality. Using selected bands from the UAE power spectrum signature, it is possible to pose the health monitoring problem as a multi-class classification problem, and make use of a single neural network to classify the ultrasonic acoustic emission signatures. Artificial training data, based on statistical properties of a significantly smaller experimental data set is used to train the neural network. This specific approach is generic enough to suggest that it is applicable to a variety of systems and components where periodic acoustic emissions exist.

  17. Multi-Scale Analysis Based Ball Bearing Defect Diagnostics Using Mahalanobis Distance and Support Vector Machine

    OpenAIRE

    Chun-Chieh Wang; Tian-Yau Wu; Chiu-Wen Wu; Shuen-De Wu

    2013-01-01

    The objective of this research is to investigate the feasibility of utilizing the multi-scale analysis and support vector machine (SVM) classification scheme to diagnose the bearing faults in rotating machinery. For complicated signals, the characteristics of dynamic systems may not be apparently observed in a scale, particularly for the fault-related features of rotating machinery. In this research, the multi-scale analysis is employed to extract the possible fault-related features in differ...

  18. Ball bearings comprising nickel-titanium and methods of manufacture thereof

    Science.gov (United States)

    DellaCorte, Christopher (Inventor); Glennon, Glenn N. (Inventor)

    2012-01-01

    Disclosed herein is a friction reducing nickel-titanium composition. The nickel-titanium composition includes a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38. A bearing for reducing friction comprising a nickel-titanium composition comprising a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38; where the bearing is free from voids and pinholes.

  19. Time-Varying Total Stiffness Matrix of a Rigid Machine Spindle-Angular Contact Ball Bearings Assembly: Theory and Analytical/Experimental Verifications

    Directory of Open Access Journals (Sweden)

    Fawzi M.A. El-Saeidy

    2011-01-01

    Full Text Available A lagrangian formulation is presented for the total dynamic stiffness and damping matrices of a rigid rotor carrying noncentral rigid disk and supported on angular contact ball bearings (ACBBs. The bearing dynamic stiffness/damping marix is derived in terms of the bearing motions (displacements/rotations and then the principal of virtual work is used to transfer it from the bearing location to the rotor mass center to obtain the total dynamic stiffness/damping matrix. The bearing analyses take into account the bearing nonlinearities, cage rotation and bearing axial preload. The coefficients of these time-dependent matrices are presented analytically. The equations of motion of a rigid rotor-ACBBs assembly are derived using Lagrange's equation. The proposed analyses on deriving the bearing stiffness matrix are verified against existing bearing analyses of SKF researchers that, in turn, were verified using both SKF softwares/experiments and we obtained typical agreements. The presented total stiffness matrix is applied to a typical grinding machine spindle studied experimentally by other researchers and excellent agreements are obtained between our analytical eigenvalues and the experimental ones. The effect of using the total full stiffness matrix versus using the total diagonal stiffness matrix on the natural frequencies and dynamic response of the rigid rotor-bearings system is studied. It is found that using the diagonal matrix affects natural frequencies values (except the axial frequency and response amplitudes and pattern and causes important vibration tones to be missig from the response spectrum. Therefore it is recommended to use the full total stiffness matrix and not the diagonal matrix in the design/vibration analysis of these rotating machines. For a machine spindle-ACBBs assembly under mass unbalnce and a horizontal force at the spindle cutting nose when the bearing time-varying stiffness matrix (bearing cage rotation is considered

  20. Petrography and microanalysis of Pennsylvanian coal-ball concretions (Herrin Coal, Illinois Basin, USA): Bearing on fossil plant preservation and coal-ball origins

    Science.gov (United States)

    Siewers, Fredrick D.; Phillips, Tom L.

    2015-11-01

    Petrographic analyses of 25 coal balls from well-studied paleobotanical profiles in the Middle Pennsylvanian Herrin Coal (Westphalian D, Illinois Basin) and five select coal balls from university collections, indicate that Herrin Coal-ball peats were permineralized by fibrous and non-fibrous carbonates. Fibrous carbonates occur in fan-like to spherulitic arrays in many intracellular (within tissue) pores, and are best developed in relatively open extracellular (between plant) pore spaces. Acid etched fibrous carbonates appear white under reflected light and possess a microcrystalline texture attributable to abundant microdolomite. Scanning electron microscopy, X-ray diffraction, and electron microprobe analysis demonstrate that individual fibers have a distinct trigonal prism morphology and are notable for their magnesium content (≈ 9-15 mol% MgCO3). Non-fibrous carbonates fill intercrystalline spaces among fibers and pores within the peat as primary precipitates and neomorphic replacements. In the immediate vicinity of plant cell walls, non-fibrous carbonates cut across fibrous carbonates as a secondary, neomorphic phase attributed to coalification of plant cell walls. Dolomite occurs as diagenetic microdolomite associated with the fibrous carbonate phase, as sparite replacements, and as void-filling cement. Maximum dolomite (50-59 wt.%) is in the top-of-seam coal-ball zone at the Sahara Mine, which is overlain by the marine Anna Shale. Coal-ball formation in the Herrin Coal began with the precipitation of fibrous high magnesium calcite. The trigonal prism morphology of the carbonate fibers suggests rapid precipitation from super-saturated, meteoric pore waters. Carbonate precipitation from marine waters is discounted on the basis of stratigraphic, paleobotanical, and stable isotopic evidence. Most non-fibrous carbonate is attributable to later diagenetic events, including void-fill replacements, recrystallization, and post-depositional fracture fills. Evidence

  1. Influence of processing medium on frictional wear properties of ball bearing steel prepared by laser surface melting coupled with bionic principles

    International Nuclear Information System (INIS)

    Coupling with bionic principles, an attempt to improve the wear resistance of ball bearing steel (GCr15) with biomimetic units on the surface was made using a pulsed Nd: YAG laser. Air and water film was employed as processing medium, respectively. The microstructures of biomimeitc units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases as functions of different mediums as well as water film with different thicknesses. The results indicated that the microstructure zones in the biomimetic specimens processed with water film were more refined and had better wear resistance increased by 55.8% in comparison with that processed in air; a significant improvement in microhardness was achieved by laser surface melting. The application of water film provided considerable microstructural changes and much more regular grain shape in biomimetic units, which played a key role in improving the wear resistance of ball bearing steel.

  2. Influence of processing medium on frictional wear properties of ball bearing steel prepared by laser surface melting coupled with bionic principles

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Hong, E-mail: wangct08@mails.jlu.edu.c [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Wang Chengtao [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Faw-Volkswagen Automotive Company Ltd., Changchun 130011 (China); Guo Qingchun [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Brilliance Automobile Engineering Research Institute, Shenyang 110141 (China); Yu Jiaxiang [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Wang Mingxing [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100190 (China); Liao Xunlong [Technical Management Department, CNNC China Zhongyuan Engineering Corp. Ltd., No 487 Tianlin Road, Shanghai 200233 (China); Zhao Yu [School of Materials Science and Engineering, Changchun University of Technology, Changchun 130012 (China); Ren Luquan [Key Lab of Terrain Machinery Bionics Engineering, Ministry of Education, Jilin University, Changchun 130025 (China)

    2010-09-03

    Coupling with bionic principles, an attempt to improve the wear resistance of ball bearing steel (GCr15) with biomimetic units on the surface was made using a pulsed Nd: YAG laser. Air and water film was employed as processing medium, respectively. The microstructures of biomimeitc units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases as functions of different mediums as well as water film with different thicknesses. The results indicated that the microstructure zones in the biomimetic specimens processed with water film were more refined and had better wear resistance increased by 55.8% in comparison with that processed in air; a significant improvement in microhardness was achieved by laser surface melting. The application of water film provided considerable microstructural changes and much more regular grain shape in biomimetic units, which played a key role in improving the wear resistance of ball bearing steel.

  3. 76 FR 35401 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Notice of Court Decision Not...

    Science.gov (United States)

    2011-06-17

    ... Bearings, and Spherical Plain Bearings, and Parts Thereof From Japan, 54 FR 20904 (May 15, 1989), and... Bearings, and Cylindrical Roller Bearings and Parts Thereof From the United Kingdom, 54 FR 20910 (May 15... Five-Year (``Sunset'') Reviews, 70 FR 31423 (June 1, 2005), and Certain Bearings From China,...

  4. Finite-Difference Solutions of the Alternate Turbopump Development High-Pressure Oxidizer Turbopump Pump-End Ball-Bearing Cavity Flows

    Science.gov (United States)

    Benjamin, Theodore G.; Garcia, Roberto; Mcconnaughey, Paul K.; Wang, Ten-See; Vu, Bruce T.; Dakhoul, Youssef

    1993-01-01

    These analyses were undertaken to aid in the understanding of flow phenomena in the Alternate Turbopump Development (ATD) High-pressure Oxidizer Turbopump (HPOTP) Pump-end ball bearing (PEBB) cavities and their roles in turbopump vibration initiation and bearing distress. This effort was being performed to provide timely support to the program in a decision as to whether or not the program should be continued. In the first case, it was determined that a change in bearing through flow had no significant effect on axial preload. This was a follow-on to a previous study which had resulted in a redesign of the bearing exit cavity which virtually eliminated bearing axial loading. In the second case, a three-dimensional analysis of the inner-race-guided cage configuration was performed so as to determine the pressure distribution on the outer race when the shaft is 0.0002 inches off-center. The results indicate that there is virtually no circumferential pressure difference caused by the offset to contribute to bearing tilt. In the third case, axisymmetric analyses were performed on an outer-race guided cage configuration to determine the magnitude of tangential flow entering the bearing. The removed-shoulder case was analyzed as was the static diverter case. A third analysis where the preload spring was shielded by a sheet of metal for the baseline case was also performed. It was determined that the swirl entering the bearing was acceptable and the project decided to use the outer-race-guided cage configuration. In the fourth case, more bearing configurations were analyzed. These analyses included thermal modeling so as to determine the added benefit of injecting colder fluid directly onto the bearing inner-race contact area. The results of these analyses contributed to a programmatic decision to include coolant injection in the design.

  5. Analysis of stresses at the bore of a drilled ball operating in a high-speed bearing. [with stiffening web

    Science.gov (United States)

    Coe, H. H.; Lynch, J. E.

    1973-01-01

    Three-dimensional stress distributions were calculated for both a regular drilled ball with a stiffening web. The balls were 20.6 mm (0.8125 in.) in diameter and had a 12.6 mm (0.496 in.) diameter concentric hole. The stiffening web was 1.5 mm (0.06 in.) thick. The calculations showed that a large reversing tangential stress at the hole bore was reduced by one-half by the addition of the web.

  6. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples.

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (10(5)/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (10(6)/ml) and SRB (10(8)/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  7. The metal-tool contact friction at the ultrasonic vibration drawing of ball-bearing steel wires

    Directory of Open Access Journals (Sweden)

    Susan, Mihai

    1999-12-01

    Full Text Available The friction reversion mechanism during the ultrasonic vibration drawing (UVD of wires has been detailed for the case when the die is located at the oscillation maxima of the waves and actuated parallel to the friction force direction. The decrease of the drawing force for the UVD technology as compared to classical drawing has been explained by means of the intermittent contact in the metal-die forming area. A relationship has been derived for the UVD friction coefficient, μUS that allowed the analytical determination of the drawing force. In the case of the Romanian RUL 1V (AISI 52100 ball bearing steel wires, a good agreement has been found between the analytical and the experimental values of the drawing forces that have decreased, as compared to classical drawing, by more than 5 % for drawing rates lower than 0.66m/s.

    Se hace un análisis pormenorizado del mecanismo de reversión de la fricción al estirado por vibraciones ultrasonoras (EVU de los alambres, para el caso en que la trefiladora está ubicada en los máximos de oscilación de las ondas y activada paralelamente a la dirección de estirado. La disminución de la fuerza de estirado para la tecnología EVU en comparación con el estirado clásico, se ha explicado a través del contacto intermitente en el área de deformación metal-herramienta. Se halló una relación para el coeficiente de fricción EVU, μUS que permitió la determinación analítica de la fuerza de estirado. En el caso de los alambres de acero rumano de rodamientos RUL 1V (AISI 52100 se encontró una justa concordancia entre los valores analítico y experimental de la fuerza de estirado que, en comparación con los de estirado clásico, se encontraron disminuidos en más de un 5 % para velocidades de estirado menores de 0,66m/s.

  8. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (105/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml) and SRB (108/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  9. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Directory of Open Access Journals (Sweden)

    Gerrit eVoordouw

    2016-03-01

    Full Text Available Microbially-influenced corrosion (MIC contributes to the general corrosion rate (CR, which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm, for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for 8 produced waters with high numbers (105/ml of acid-producing bacteria (APB, but no sulfate-reducing bacteria (SRB. Average CRs were 0.009 mm/yr for 5 central processing facility (CPF waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml and SRB (108/ml. Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  10. 76 FR 41761 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Revocation of Antidumping Duty...

    Science.gov (United States)

    2011-07-15

    ... Plain Bearings, and Parts Thereof From Japan, 54 FR 20904 (May 15, 1989), and Antidumping Duty Orders... Cylindrical Roller Bearings and Parts Thereof From the United Kingdom, 54 FR 20910 (May 15, 1989). Pursuant to... Initiation of Five-year (``Sunset'') Reviews, 70 FR 31423 (June 1, 2005); Certain Bearings From China,...

  11. A preliminary study on the development of La2O3-bearing nanostructured ferritic steels via high energy ball milling

    International Nuclear Information System (INIS)

    Elemental powder mixture of Fe–Cr–Ti–Mo and La2O3 were ball milled for different milling times in a high energy shaker mill. Effects of ball milling time on crystallite size, particle size and hardness were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester. After 10 h of ball milling, the smallest crystallite size and highest hardness were ∼24 nm and ∼970 HV, respectively. Transmission electron microscopy (TEM) studies have revealed nanoscale features 2–5 nm in diameter present in the milled powder. Local atom probe tomography studies have shown that these nanoscale features were possibly nanoclusters enriched in La, TiO and O

  12. Seismic Isolation Study of Large-scale Aqueduct with Ball Bearings%球型支座应用于大型渡槽的隔震研究

    Institute of Scientific and Technical Information of China (English)

    张艳红; 胡晓; 胡选儒; 和秀芬; 欧阳先凯

    2011-01-01

    结合实际大型渡槽工程,设计球型隔震支座NKQZ15000GD,该支座具有较高的竖向承载能力、较低的水平剪切刚度,并具有一定阻尼和复位能力;对该支座进行材料性能测试,拟合支座的力学性能参数;分别采用反应谱法和动力时程法,计算隔震渡槽在设计地震与超设计地震作用下的动力反应;分析球型隔震支座应用于大型渡槽的减震效果,根据定量分析的结果得到一些规律性的结论.%For the actual large-scale aqueduct project, a ball isolation bearings NKQZ15000GD was designed, which showed a higher vertical bearing capacit, lower shear stiffness,certain damping and reset capability. Material testing was conducted on the bearings and the mechanical parameters were obtained by test data fitting. The response spectrum method and dynamic time-history method were used to analyze the seismic responses of isolation aqueduct under the designed earthquake and super-designed earthquake. Damping effect of the ball bearings set in the large-scale aqueduct was also analyzed. According to the results of quantitative analyses,some regularity conclusions were given.

  13. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  14. Fretting Wear Behavior of Angular Contact Ball Bearings%角接触球轴承微动磨损行为

    Institute of Scientific and Technical Information of China (English)

    王思明; 高宏力; 许明恒

    2012-01-01

    为了解载荷、摆动角度和循环次数对角接触球轴承微动磨损行为的影响,用自制的轴承微动试验装置对角接触球轴承QJ208在干态下进行了3种摆角(0.88°、1.21°和1.54°)、4种轴向载荷(2.5、5.0、10.0和20.0 kN)、2种循环次数(2和12万次)的摆动微动试验,在此基础上,对轴承磨痕进行分析.结果表明:外圈上微动磨损随载荷增大而减缓,随摆角增大而加重,随循环次数的增加,其磨损增幅趋缓;在摆角为0.88°时,磨损机制以疲劳磨损为主,在摆角为1.54°时,则以磨粒磨损为主;在同一钢球接触处,外圈上的磨痕比内圈上的磨痕严重.%In order to investigate the fretting wear behavior of angular contact ball bearings under different loads, oscillation angles, and number of cycles, a series of tests for angular contact ball bearings ( QJ208) were performed under dry condition on a self-made bearing fretting wear test rig with four axial loads (2. 5, 5. 0, 10. 0, and 20. 0 kN) , three oscillation angles (0. 88°, 1. 21°, and 1.54°) and two cycle numbers (2 × 10 and 12 × 10 ). The fretting wear behavior was analyzed in combination with microscopic examinations on worn scars. The results show that the fretting wear on the outer ring reduces with the increasing load, but increases with the increasing oscillation angle. As the number of cycles increases, the growth rate of wear slows down. In addition, the wear mechanism is dominated by fatigue wear at the oscillation angle of 0. 88°, and by abrasive wear at the oscillation angle of 1. 54°. For each ball, the wear damage on the outer ring is more serious than that on the inner ring.

  15. Effect of Ceramic Ball and Hybrid Stainless Steel Bearing/Wheel Combinations on the Lifetime of a Precision Translation Stage for the SIM Flight Project

    Science.gov (United States)

    Lo, C. John; Klein, Kerry; Jones, William R., Jr.; Jansen, Mark J.; Wemhoner, Jens

    2009-01-01

    A study of hybrid material couples using the Spiral Orbit Tribometer (SOT) was initiated to investigate both lubricated (Pennzane X2000 and Brayco 815Z) and unlubricated Si3N4, 440C SS, Rex 20, Cronidur X30 and X40 plates with Cerbec SN-101-C (Si3N4) and 440C balls. The hybrid wheel/bearing assembly will be used on the Linear Optical Delay Line (LODL) stage as an element of the NASA Space Interferometry Mission (SIM). SIM is an orbiting interferometer linking a pair of telescopes within the spacecraft and, by using an interferometry technique and several precision optical stages, is able to measure the motions of known stars much better than current ground or space based systems. This measurement will provide the data to "infer" the existence of any plants, undetectable by other methods, orbiting these known stars.

  16. Restoration of bearings

    Science.gov (United States)

    Parker, R. J.; Zaretsky, E. V.; Hanau, H.

    1977-01-01

    Process consisting of grinding raceways to oversize but original quality condition and installing new oversize balls or bearings restores wornout ball and roller bearings to original quality, thereby doubling their operating life. Evaluations reveal process results in restoration of 90% of replaced bearings at less than 50% of new-bearing costs.

  17. 75 FR 34688 - Ball Bearings and Parts Thereof from France: Final Results of Changed-Circumstances Review

    Science.gov (United States)

    2010-06-18

    ... Bearings and Parts Thereof From France: Initiation of Antidumping Duty Changed-Circumstances Review, 74 FR...: Preliminary Results of Changed- Circumstances Review, 74 FR 60242 (November 20, 2009). We received case briefs... Reviews and Rescission of Review in Part, 72 FR 58053, 58054 (October 12, 2007). Notification This...

  18. Analysis on Stress Field and Relative Fatigue Life of Angular Contact Ball Bearings%角接触球轴承的应力场与相对疲劳寿命分析

    Institute of Scientific and Technical Information of China (English)

    程超; 汪久根; 王爱林; 洪玉芳

    2013-01-01

    Based on the elastic contact theory and fatigue life computational model of Ioannides and Harris, the effects of ball diameter, groove curvature radius coefficient and radial clearance on the Hertz contact stress, Mises stress field of parts surface and fatigue life of angular contact ball bearings are analyzed. The results show that fatigue cracks originate in the circumferential plane for the parts of angular contact ball bearings, the fatigue life of bearings increases with the increase of ball diameter and decreases with the increase of groove curvature radius coefficient and radial clearance.%基于弹性接触理论及Ioannides及Harris疲劳寿命计算模型,分析了球径变化、沟曲率半径系数和径向游隙对角接触球轴承的Hertz接触应力、零件表层的Mises应力场及轴承疲劳寿命的影响.研究结果表明,角接触球轴承零件的表层裂纹源在沿轴承零件的周向平面内;轴承疲劳寿命随球径的增大而增大,随沟曲率半径系数和径向游隙的增大而减小.

  19. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  20. Flexure Bearing Reduces Startup Friction

    Science.gov (United States)

    Clingman, W. Dean

    1991-01-01

    Design concept for ball bearing incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure bearing, flexing elements placed between outer race of ball bearing and outer ring. Elements flex when ball bearings encounter small frictional-torque "bumps" or even larger ones when bearing balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for bearings in gimbals on laser and/or antenna mirrors.

  1. Holy balls!

    OpenAIRE

    Wright, Michael; Langley, Ken; Belden, Jesse; Truscott, Tadd

    2011-01-01

    We demonstrate the behavior of three balls skipping off of the water surface: a Superball, a racquetball, and a water bouncing ball (Waboba). The three balls have rebound coefficients of 0.9, 0.8 and 0.2, respectively. However, we notice that the Waboba bounces better than the others, but why? The Superball has a high coefficient of restitution, creating large rebounds. Here the impact is angled to the free surface, but the inelastic response and large mass ratio forces the ball underwater wi...

  2. Flexible-body Dynamics Analysis on Cage of High-speed Angular Contact Ball Bearing%高速角接触球轴承保持架柔体动力学分析

    Institute of Scientific and Technical Information of China (English)

    邓四二; 谢鹏飞; 杨海生; 高银涛

    2011-01-01

    在角接触球轴承动力学分析基础上,结合轴承保持架的柔体性,采用修正的Craig-Bampton子结构模态综合法建立高速角接触球轴承保持架柔体动力学方程.利用ADAMS系统开发了角接触球轴承刚柔多体动力学分析程序,对高速角接触球轴承保持架动态性能进行了分析;并采用Gupta的角接触球轴承动力学分析结果加以验证.分析结果表明:角接触球轴承引导间隙与兜孔间隙之比、径向载荷与轴向载荷之比过大或过小都不利于保持架转动的平稳性;相对刚体保持架而言,柔体保持架转动更为平稳.%A dynamic analysis method for the flexible cage dynamic formula of high-speed angular contact ball bearing was described. The flexible cage dynamic formula of high-speed angular contact ball bearing computational formulation was established using a modified Craig-Bampton component mode synthesis method based on angular contact ball bearing dynamics analysis. The dynamic characteristics of cage of high-speed angular contact ball bearing was analyzed using rigid-flexible multi-body dynamic analysis program ADAMS, and was verified by the computation example of Gupta. The results show that the rotary smoothness of cage will be broken if the ratio of pocket clearance to guided clearance and the ratio of radial load to axial load become too large or too small. The flexible cage runs more smoothly compared to the rigid cage.

  3. A novel eccentric lapping machine for finishing advanced ceramic balls

    OpenAIRE

    Kang, J.; Hadfield, M.

    2001-01-01

    Advanced ceramic balls are used extensively in hybrid precision ball bearings and show advantages in high speed, high temperature, high load and hostile environment. Finishing these balls with high quality, good efficiency and low cost is critical to their widespread application. A brief review of the methods for finishing ceramic balls is presented. The design of a novel eccentric lapping machine for finishing advanced ceramic balls is described. The kinematics of eccentric lapping is analys...

  4. Holy balls!

    Science.gov (United States)

    Truscott, Tadd; Belden, Jesse

    2011-11-01

    Why can some balls walk on water while others cannot? We investigate the rebound dynamics of elastic spheres impacting on a free-surface. Several variables determine whether or not a sphere will bounce when impacting a free-surface including velocity, impact angle, size and elasticity. Stiff elastic spheres, such as a racquetball, successfully skip at low impact angles and high velocities, but tend not to bounce when the impact angle becomes too large. However, the more compliant Waboba (WAter BOuncing BAll) bounces marvelously even at very high impact angles. Unlike a stiffer ball, the Waboba flattens out quickly as it is forming a cavity. The cavity lip forms a ramp and the flattened ball then skips off the water surface. We demonstrate how this phenomenon surprisingly resembles a skipping stone. Using high-speed video we explore the rebound dynamics for various values of elasticity, velocity, angle and size and determine when an object will bounce off the water surface.

  5. plasma ball

    CERN Multimedia

    When you touch the ball, by earthing the surface, you increase the voltage difference between it and the centre. So more electrons flow through the gas at that point, creating the filaments of light you see.

  6. Golf Ball

    Science.gov (United States)

    1998-01-01

    The Ultra 500 Series golf balls, introduced in 1995 by Wilson Sporting Goods Company, has 500 dimples arranged in a pattern of 60 spherical triangles. The design employs NASA's aerodynamics technology analysis of air loads of the tank and Shuttle orbiter that was performed under the Space Shuttle External Tank program. According to Wilson, this technology provides 'the most symmetrical ball surface available, sustaining initial velocity longer and producing the most stable ball flight for unmatched accuracy and distance.' The dimples are in three sizes, shapes and depths mathematically positioned for the best effect. The selection of dimples and their placement optimizes the interaction of opposing forces of lift and drag. Large dimples reduce air drag, enhance lift, and maintain spin for distance. Small dimples prevent excessive lift that destabilizes the ball flight and the medium size dimples blend the other two.

  7. 磁性液体离心密封深沟球轴承设计与试验%Design and test of the ferrofuild centrifugal seal deep groove ball bearings

    Institute of Scientific and Technical Information of China (English)

    薛晨阳; 王正良; 薛立新; 陈善飞

    2015-01-01

    将磁性液体特殊的零泄漏密封性能与流体离心密封可获较高压强的特性有机结合,在动力学计算分析基础上,开展磁性液体离心密封件的磁场仿真模拟,实施磁性液体离心密封深沟球轴承的优化设计与试制。在对两组轴承分别实施无密封处理及磁性液体离心密封处理后,本实验将两组轴承置于密闭空间内并对其运转时释放的微粒进行探测实验。实验发现未经密封处理的轴承释放出大量微粒,而实施磁性液体密封处理的轴承对密闭空间几乎没有明显微粒释放。结果表明,这种磁性液体离心密封的深沟球轴承能有效地减少润滑剂的散失和磨损微粒的排放,适用于高度洁净和真空的特殊环境。%Combining the special behavior of ferrofluid in no leaking seals and the high pressure in fluid based centrifugal seals, using the knowledge of computational hydrodynamic analysis, in this paper, the simulation of ferrofuild centrifugal seals is carried out to design and optimize for ball bearings. We set two bearings respectively in non-sealed and ferrofluid sealed conditions, then detect the particle concentration released by bearings in obdurate environment. The results clearly show that, the particle concentration released from non-sealed bearing increases significantly while the particle concentration from ferrofluid-sealed bearing stays steady. According to the test, this type of ferrofuild centrifugal seals for ball bearings can significantly reduce the loss of lubricant and the emission of wearing particles into the air, which shows a strong evidence that it can be used under the extreme clean or vacuum circumstance.

  8. Holy balls!

    CERN Document Server

    Wright, Michael; Belden, Jesse; Truscott, Tadd

    2011-01-01

    We demonstrate the behavior of three balls skipping off of the water surface: a Superball, a racquetball, and a water bouncing ball (Waboba). The three balls have rebound coefficients of 0.9, 0.8 and 0.2, respectively. However, we notice that the Waboba bounces better than the others, but why? The Superball has a high coefficient of restitution, creating large rebounds. Here the impact is angled to the free surface, but the inelastic response and large mass ratio forces the ball underwater without skipping. The racquetball has a lower mass ratio and a more elastic response to impacts. Also thrown at a shallow angle, it bounces off of the surface of the water 1-3 times before coming to rest. The Waboba flattens inside the cavity allowing it to skip off of the surface more easily. The flattened ball looks more like a skipping stone than a sphere due to its large elastic deformation at impact. Examining the reaction of a skipping stone we see that the stone creates a cavity in which it planes, slipping out of it...

  9. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

    The Table of Contents for the full book PDF is as follows: * Organizing Committee * Preface * Ball Lightning -- The Continuing Challenge * Hungarian Ball Lightning Observations in 1987 * Nature of Ball Lightning in Japan * Phenomenological and Psychological Analysis of 150 Austrian Ball Lightning Reports * Physical Problems and Physical Properties of Ball Lightning * Statistical Analysis of the Ball Lightning Properties * A Fluid-Dynamical Model for Ball Lightning and Bead Lightning * The Lifetime of Hill's Vortex * Electrical and Radiative Properties of Ball Lightning * The Candle Flame as a Model of Ball Lightning * A Model for Ball Lightning * The High-Temperature Physico-Chemical Processes in the Lightning Storm Atmosphere (A Physico-Chemical Model of Ball Lightning) * New Approach to Ball Lightning * A Calculation of Electric Field of Ball Lightning * The Physical Explanation to the UFO over Xinjiang, Northern West China * Electric Reconnection, Critical Ionization Velocity, Ponderomotive Force, and Their Applications to Triggered and Ball Lightning * The PLASMAK™ Configuration and Ball Lightning * Experimental Research on Ball Lightning * Performance of High-Voltage Test Facility Designed for Investigation of Ball Lightning * List of Participants

  10. Structural dynamic analysis of a ball joint

    Science.gov (United States)

    Hwang, Seok-Cheol; Lee, Kwon-Hee

    2012-11-01

    Ball joint is a rotating and swiveling element that is typically installed at the interface between two parts. In an automobile, the ball joint is the component that connects the control arms to the steering knuckle. The ball joint can also be installed in linkage systems for motion control applications. This paper describes the simulation strategy for a ball joint analysis, considering manufacturing process. Its manufacturing process can be divided into plugging and spinning. Then, the interested responses is selected as the stress distribution generated between its ball and bearing. In this paper, a commercial code of NX DAFUL using an implicit integration method is introduced to calculate the response. In addition, the gap analysis is performed to investigate the fitness, focusing on the response of the displacement of a ball stud. Also, the optimum design is suggested through case studies.

  11. 带弹性支承的角接触球轴承动态特性分析%Analysis on Dynamic Performance of Angular Contact Ball Bearings with Elastic Support

    Institute of Scientific and Technical Information of China (English)

    陈宏; 闫亚超; 邓四二; 杨海生

    2013-01-01

    针对航空发动机中的轴承支承模型,在有限元分析和轴承动力学的基础上,采用修正的Craig-Bampton 固定界面模态综合法,建立了弹性支承结构与刚性的轴承外圈、轴承座之间的耦合连接,开发了带弹性支承的角接触球轴承动力学分析模型,分析并讨论了不同工况下,弹性支承体对轴承振动特性的影响.结果表明:与刚性支承相比,弹性支承能够降低系统固有频率下的振动幅值.轴承在轴向力作用下,力较小时,增大支承体的刚度能够降低振动幅值,力较大时,采用适当刚度的弹性支承有利于减小振动幅值;轴承在径向力作用下,存在一个合理的弹性支承刚度,使径向振动幅值达到最小.%Taking a bearing support model of aero-engine as the object of study,the mathematical model of dynamic analysis for the angular contact ball bearing with elastic support is established using modified Craig-Bampton component mode synthesis method which coupling the elastic support with the outer ring and housing based on finite element method and bearing dynamics analysis.The factors of elastic support which influence the vibration characteristics of bearing system under different working conditions are analyzed and discussed.The analysis results show that elastic support is able to decrease the amplitude value caused by inherent frequencies compared with rigid support.Under a small axial load,increasing the rigidity of the elastic support is more helpful for decreasing the magnitude of beating vibration;under a heavy load,taking the elastic support with the proper rigidity is benefit for decreasing the magnitude of bearing vibration.There is a reasonable rigidity of elastic support to get the minimum of radial vibration amplitude.

  12. Probabilistic Aspect of Rolling Bearings Durability

    OpenAIRE

    Styp-Rekowski, Michał

    2007-01-01

    Many factors generate situations that real dimensions of each machine elements are different from nominal ones. In the case of rolling bearings elements mentioned disagreements are small - their values are rank of micrometers. However, such small differences can generate significant changes of operational features of bearings. The analysis of influence of ball dimensional deviation on load distribution in ball bearings is presented in this paper. The probability of occurrence of ball diameter...

  13. Four ball best ball 1.

    Science.gov (United States)

    Pollard, Geoff; Pollard, Graham

    2010-01-01

    In this paper a four-ball-best-ball (4BBB) model for pairs of golf players is set up. The 4BBB match-play scoring system is seen to satisfy a basic requirement of fairness. It is shown that it is not strictly possible to rate individual players as 4BBB players. However, a (reasonably broad) class of individual players is identified such that it is possible to rate them individually as 4BBB players. The capacity of an individual to play birdies is seen to be a very important determinant in being a successful member of a 4BBB pair, but there are other minor factors as well. Consideration is given to equal and unequal 4BBB pairs. The transitive law is seen to apply for 4BBB pairs. Thus, if pair A is better than pair B, and pair B is better than pair C, then pair A must be better than pair C. Correspondingly, if pair A is equal to pair B, and pair B is equal to pair C, then pair A is equal to pair C. Consideration is given to some strategic issues in 4BBB match-play golf. For example, the conditions under which a player should take a greater risk and have a higher probability of obtaining a bogie in order to achieve a higher probability of scoring a birdie, are determined. Also, the conditions under which a player, noting that his partner is about to have a 'bad' hole and score only a par or a bogie, should 'play safe', are determined. Thirdly, players who can interact in certain ways are seen to have an advantage over those pairs that cannot do this. Finally, one pair's optimal strategy when they see that their opponents are about to score a par or a bogie, but not a birdie, is analyzed. Key pointsA model for four-ball-best-ball match-play golf is established, and used to show that, although there can be other factors, the capacity of an individual to play birdies is a very important determinant in that player being a successful member of a four-ball-best-ball pair.Although it is not possible in general to rate play-ers individually as 4BBB players, a class of indi

  14. FOUR BALL BEST BALL 1

    Directory of Open Access Journals (Sweden)

    Geoff Pollard

    2010-03-01

    Full Text Available In this paper a four-ball-best-ball (4BBB model for pairs of golf players is set up. The 4BBB match-play scoring system is seen to satisfy a basic requirement of fairness. It is shown that it is not strictly possible to rate individual players as 4BBB players. However, a (reasonably broad class of individual players is identified such that it is possible to rate them individually as 4BBB players. The capacity of an individual to play birdies is seen to be a very important determinant in being a successful member of a 4BBB pair, but there are other minor factors as well. Consideration is given to equal and unequal 4BBB pairs. The transitive law is seen to apply for 4BBB pairs. Thus, if pair A is better than pair B, and pair B is better than pair C, then pair A must be better than pair C. Correspondingly, if pair A is equal to pair B, and pair B is equal to pair C, then pair A is equal to pair C. Consideration is given to some strategic issues in 4BBB match-play golf. For example, the conditions under which a player should take a greater risk and have a higher probability of obtaining a bogie in order to achieve a higher probability of scoring a birdie, are determined. Also, the conditions under which a player, noting that his partner is about to have a ‘bad’ hole and score only a par or a bogie, should ‘play safe’, are determined. Thirdly, players who can interact in certain ways are seen to have an advantage over those pairs that cannot do this. Finally, one pair’s optimal strategy when they see that their opponents are about to score a par or a bogie, but not a birdie, is analyzed

  15. Autosizing Control Panel for Needle Bearing

    OpenAIRE

    Prof.A.R.Wadhekar,; Ms Jyoti R. Rajput

    2016-01-01

    A needle roller bearing is a bearing which uses small cylindrical rollers. Bearings are used to reduce friction of any rotating surface. Needle bearings have a large surface in contact with the bearing outer surfaces as compared to ball bearings. There is less added clearance(Diameter of the shaft and the diameter of the bearing are different) so they are much compact. The structure consists of a needle cage which contains the needle rollersthemselves and an outer race (The housin...

  16. Having a Ball with Fitness Balls

    Science.gov (United States)

    McNulty, Betty

    2011-01-01

    Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

  17. Ball Screw Actuator Including a Compliant Ball Screw Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2015-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  18. Experimental Research on Residual Stress in Surface of Silicon Nitride Ceramic Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The influence of the residual stress in surface of ceramic balls on the fatigue life is large, because the life of silicon nitride ball bearings is more sensitive to the load acted on the bearings than the life of all-steel ball bearings. In this paper, the influence of thermal stress produced in sintering and mechanical stress formed in lapping process on residual stress in surface of silicon nitride ceramic balls was discussed. The residual compress stress will be formed in the surface of silicon nitride ...

  19. Q-ball metamorphosis

    International Nuclear Information System (INIS)

    Flat directions in the minimal supersymmetric standard model are known to deform into nontopological solitons, Q balls, which generally possess both baryon and lepton asymmetries. We investigate how Q balls evolve if some of the constituent fields of the flat direction decay into light species. It is found that the Q balls takes a new configuration whose energy per charge slightly increases due to the decay. Specifically, we show that all the stable Q balls eventually transform into pure B balls via the decay into neutrinos

  20. Q-ball Metamorphosis

    CERN Document Server

    Kawasaki, Masahiro; Kawasaki, Masahiro; Takahashi, Fuminobu

    2004-01-01

    Flat directions in the minimal supersymmetric standard model are known to deform into non-topological solitons, Q-balls, which generally possess both baryon and lepton asymmetries. We investigate how Q-balls evolve if some of the constituent fields of the flat direction decay into light species. It is found that the Q-balls takes a new configuration whose energy per charge slightly increases due to the decay. Specifically, we show that all the stable Q-balls eventually transform into pure B-balls via the decay into neutrinos.

  1. Research on Abrasives in the Chemical Mechanical Polishing Process for Silicon Nitride Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fields, such as high speed and high temperature areojet engines, precision machine tools and chemical engineer machines. Silicon nitride ceramics is a kind of brittle and hard material that is difficult to machining. In the traditional finishing process of silicon nitride balls, balls are lapped...

  2. Actuated Ball Sports

    OpenAIRE

    Clerix, Ben

    2015-01-01

    Ball sports offer many physical, mental and social benefits, however they each require a different set of attributes, such as basketball hoops, volleyball nets, bowling pins, etc. Thus in order to play each of these ball sports, we need to provide and manually set up each of different attributes. Digital ball sports on the other hand virtualise these different attributes at the cost of losing physicality, however they have the possibility to create non-realistic experiences. Without physicali...

  3. Toric symplectic ball packing

    OpenAIRE

    Pelayo, Alvaro

    2007-01-01

    We define and solve the toric version of the symplectic ball packing problem, in the sense of listing all 2n-dimensional symplectic-toric manifolds which admit a perfect packing by balls embedded in a symplectic and torus equivariant fashion. In order to do this we first describe a problem in geometric-combinatorics which is equivalent to the toric symplectic ball packing problem. Then we solve this problem using arguments from Convex Geometry and Delzant theory. Applications to symplectic bl...

  4. Physics of ball sports

    Science.gov (United States)

    Cohen, C.; Clanet, C.

    2016-06-01

    Ball sports have been part of human history for thousands of years [1]. Nowadays, 13 of them are part of the Olympic games (badminton, basketball, beach volley, football/soccer, golf, handball, hockey, rugby, table tennis, tennis, volleyball, water polo, ice hockey). All these games differ by launcher (hand, club, racket, bat), ball (size, shape and mass), pitch size and number of players. These differences induce different ball velocities. Apart from the velocities and the way to maximize them, we discuss in this article the ball trajectories and their impact on the size of sports fields.

  5. Large gauged Q balls

    Science.gov (United States)

    Anagnostopoulos, K. N.; Axenides, M.; Floratos, E. G.; Tetradis, N.

    2001-12-01

    We study Q balls associated with local U(1) symmetries. Such Q balls are expected to become unstable for large values of their charge because of the repulsion mediated by the gauge force. We consider the possibility that the repulsion is eliminated through the presence in the interior of the Q ball of fermions with charge opposite to that of the scalar condensate. Another possibility is that two scalar condensates of opposite charge form in the interior. We demonstrate that both these scenarios can lead to the existence of classically stable, large, gauged Q balls. We present numerical solutions, as well as an analytical treatment of the ``thin-wall'' limit.

  6. Borner Ball Neutron Detector

    Science.gov (United States)

    2002-01-01

    The Bonner Ball Neutron Detector measures neutron radiation. Neutrons are uncharged atomic particles that have the ability to penetrate living tissues, harming human beings in space. The Bonner Ball Neutron Detector is one of three radiation experiments during Expedition Two. The others are the Phantom Torso and Dosimetric Mapping.

  7. Ball screw inspection setup

    Science.gov (United States)

    Janusz, Rzepka; Sambor, Slawomir; Pienkowski, Janusz; Bielenin, Marcin

    2003-05-01

    In the following paper we describe arrangements of laser interferometer for investigation of screws and for inspection of ball screws. We have constructed two of them, namely: the technological setup for investigations of screw in process of production and the ball screw inspection setup. The former one is used to measure the pitch of screws. The data gathered during measurement is used to calculate the parameters for grinding machine. The later setup is used for testing parameters of complete ball screws. The software supporting this setup makes calculation of parameters of tested ball screw and creation of reports possible. Additionally, the inspection setup is the one that the torque measuring arrangements have been integrated on. Both the arrangements and the software allow for measurements of all parameters during movement of nut in full travel length of the ball screw and make charts and reports.

  8. Happy Balls, Unhappy Balls, and Newton's Cradle

    Science.gov (United States)

    Kagan, David

    2010-01-01

    The intricacies of Newton's Cradle are well covered in the literature going as far back as the time of Newton! These discussions generally center on the highly elastic collisions of metal spheres. Thanks to the invention of happy and unhappy balls, you can build and study the interaction of less elastic systems (see Fig. 1).

  9. Fatigue life estimation of ball screw in control element drive mechanism of SMART

    International Nuclear Information System (INIS)

    Various kinds of mechanisms are applied or studied for the driving control elements in reactors. One of these mechanisms is a ball screw type drive mechanism, which has advantages in precise operation and high stiffness. So this system is one of the candidate control element drive mechanism of SMART. The fatigue lifes of ball bearing and ball screws are generally limited by flaking at normal operation and are estimated by statistical method. A method to estimate the fatigue life of the ball screw on a control element drive mechanism is presented, and the suitability of ball screw type mechanism is discussed in this paper

  10. Compact Q-balls

    CERN Document Server

    Bazeia, D; Marques, M A; Menezes, R; da Rocha, R

    2016-01-01

    In this work we deal with non-topological solutions of the Q-ball type in two space-time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  11. Spinning Q-Balls

    OpenAIRE

    Volkov, Mikhail S.; Woehnert, Erik

    2002-01-01

    We present numerical evidence for the existence of spinning generalizations for non-topological Q-ball solitons in the theory of a complex scalar field with a non-renormalizable self-interaction. To the best of our knowledge, this provides the first explicit example of spinning solitons in 3+1 dimensional Minkowski space. In addition, we find an infinite discrete family of radial excitations of non-rotating Q-balls, and construct also spinning Q-balls in 2+1 dimensions.

  12. Aerodynamics of sports balls

    Science.gov (United States)

    Mehta, R. D.

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  13. Bearing fatigue investigation 3

    Science.gov (United States)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  14. Tunguska Dark Matter Ball

    CERN Document Server

    Froggatt, C D

    2014-01-01

    It is suggested that the Tunguska event in June 1908 cm-large was due to a cm-large ball of a condensate of bound states of 6 top and 6 anti-top quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.

  15. The bowling balls

    CERN Document Server

    CERN Bulletin

    2010-01-01

    10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…   The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse. Almost 40 years ago, the web, Wikipedia and Google did not exist and it was much more difficult to know whether other people in other parts of the world or even in the same laboratory were facing the same problems or developing the same tools. At that time, Bent Stumpe was an electronics engineer, newly recruited to work on developments for the SPS Central Control room. One of the things his supervisor asked him to build as soon as possible was a device to control a pointer on a screen, also called a tracker ball. The heart of the device was the...

  16. Laboratory demonstration of ball lightning

    International Nuclear Information System (INIS)

    A common laboratory facility for creating glowing flying plasmoids akin to a natural ball lightning, allowing a number of experiments to be performed to investigate the main properties of ball lightning, is described. (methodological notes)

  17. Lubricant replacement in rolling element bearings for weapon surety devices

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

    1996-05-01

    Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

  18. Measurement method for turned outer ring groove position of medium and small size single row angular contact ball bearing%中小型单列角接触球轴承车外沟道位置检测方法的改进

    Institute of Scientific and Technical Information of China (English)

    杨秀玲

    2012-01-01

      While turning the groove of medium and small size single row angular contact ball bearing, groove position is measured with template, which results in larger error and more scraps and the groove runout to the face can’t be measured. By modification of measuring method, the groove quality is considerably improved with master and gauge , so as to reduce scrap rate and production cost.%  车加工中、小型单列角接触球轴承套圈的沟道时,沟位置用样板透光法测量,误差较大,产生废品较多,而且无法检测沟侧摆。通过改进检测方法,用标准样件对表测量,使沟道质量明显提高,降低了废损率,节约了生产成本。

  19. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  20. Rolling-element fatigue life of silicon nitride balls. [as compared to that of steel, ceramic, and cermet materials

    Science.gov (United States)

    Parker, R. J.; Zaretsky, E. V.

    1974-01-01

    The five-ball fatigue tester was used to evaluate silicon nitride as a rolling-element bearing material. Results indicate that hot-pressed silicon nitride running against steel may be expected to yield fatigue lives comparable to or greater than those of bearing quality steel running against steel at stress levels typical rolling-element bearing application. The fatigue life of hot-pressed silicon nitride is considerably greater than that of any ceramic or cermet tested. Computer analysis indicates that there is no improvement in the lives of 120-mm-bore angular--contact ball bearings of the same geometry operating at DN values from 2 to 4 million where hot-pressed silicon nitride balls are used in place of steel balls.

  1. Hurwitz ball quotients

    OpenAIRE

    Stover, Matthew

    2013-01-01

    We consider the analogue of Hurwitz curves, smooth projective curves $C$ of genus $g \\ge 2$ that realize equality in the Hurwitz bound $|\\mathrm{Aut}(C)| \\le 84 (g - 1)$, to smooth compact quotients $S$ of the unit ball in $\\mathbb{C}^2$. When $S$ is arithmetic, we show that $|\\mathrm{Aut}(S)| \\le 288 e(S)$, where $e(S)$ is the (topological) Euler characteristic, and in the case of equality show that $S$ is a regular cover of a particular Deligne--Mostow orbifold. We conjecture that this ineq...

  2. Electromagnetic nondestructive detection for wounded bearings and impellers and correlation of size of defect and signal

    International Nuclear Information System (INIS)

    A new electromagnetic method for the nondestructive evaluation of electric pumps with ball bearing is proposed. A permanent magnet generates a static magnetic field and a coil of several hundred turns wrapped around it is used to pick up eddy currents induced inside rotating ball bearings and impellers. First, a method that make use of the autocorrelation is applied to the signals of the ball bearings. A relation between the processed signals and the size of the defects in the bearings is obtained. In a second part, the signal of the rotating impeller is measured. The analysis of the measured signal allows evaluating the displacement of the shaft and of the impeller. (author)

  3. Elid superfinishing of spherical bearings

    OpenAIRE

    Raffles, Mark H.

    2007-01-01

    Driven by a requirement to extend the lifespan of self-aligning lined spherical bearings, this research investigates the use of Elid (electrolytic in-process dressing) as a method of improving ball surface finish. Elid is a continuous and self-regulating electrochemical dressing process that modifies the surface of a grinding, lapping, or superfinishing wheel. It provides improved grit protrusion, impedes wheel loading / glazing and promotes effective cutting. The characteri...

  4. Holy Balls!: Part Deux

    Science.gov (United States)

    Belden, Jesse; Jandron, Michael; Truscott, Tadd

    2012-11-01

    A Waboba® (WAter BOuncing BAll) demonstrates remarkable water skipping behavior, even at relatively large impact angles. The highly compliant nature of these elastic spheres results in significant deformation into a disk-like shape upon impact. The increased wetted area and force coefficient generates a large hydrodynamic force that more readily lifts the ball off the water surface. However, elasticity introduces some surprising phenomena, such as material waves that propagate on the sphere and interact with the water cavity. Depending upon impact conditions, material waves may propagate in various directions combining to create multiple modes of deformation and complicated fluid-structure interactions. Furthermore, the timescales of deformation and wave propagation depend on the material properties and impact conditions. In this talk, we will discuss skipping regimes in terms of impact parameters and material properties and relate failed skipping behavior to the structure-fluid interaction caused by deformation. The critical timescales for deformation, wave propagation and collision will be related to the relevant physical parameters of the problem.

  5. Ball lightning: a realistic model

    International Nuclear Information System (INIS)

    Ball lightning is a rare and beautiful phenomenon, still lacking a scientific explanation. Here, the main ideas of a recent topological model are summarized. This model provides reasons for the stability of the ball and it is able to explain some curious contradictions in the reports of the witnesses. (Author) 3 refs

  6. Experimental research on ball lightning

    International Nuclear Information System (INIS)

    Experiments on producing ball lightning were made with discharge in flammable gas and/or aerosol. A long lifetime (2 s) ball lightning was observed in 2.7 % ethane and 100 cm3 cotton fibers, and in 1.5 % methane and 1.9 % ethane

  7. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  8. Development and Evaluation of Titanium Spacesuit Bearings

    Science.gov (United States)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Raymond, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z-series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z-series space suit architecture allows us to reduce mass by an estimated 23 lbs per suit system compared to the previously used stainless steel bearing race designs, without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race- 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility (WSTF) that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approx. 3 years), design parameters for maximum contact stress need to be identified. To identify these design parameters, bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination and design around a cycle life requirement for an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an

  9. Prediction of tar ball formation

    Energy Technology Data Exchange (ETDEWEB)

    Khelifa, A.; Gamble, L. [Environment Canada, Ottawa, ON (Canada). Emergencies Science and Technology Division, Environmental Technology Centre, Science and Technology Branch

    2006-07-01

    The presence of small tar balls ranging in size from less than a millimetre to 60 centimetres have been observed during cleanup assessment operations following accidental oil spills on water. The tar balls are composed of heavy oil residues and suspended particulate matter (SPM) from the water column. They can be found on shorelines, settled on the seafloor and floating at or near the water surface. Their abundance on the shorelines varies from site to site and depends on the conditions of the spill and mixing conditions. Aggregation between SPM and micro-sized oil droplets occurs naturally in coastal waters and enhances the dispersion of spilled oil. Although tar balls are among the important end states of spilled oil in the marine environment, no model exists to estimate the percentage of the spilled oil that becomes tar balls. This paper offered some insight into the modeling of tar ball formation. Current modeling understanding of oil-SPM aggregate formation was used to predict tar ball formation. The formation of oil droplets was examined with respect to a range of conditions under which the formation of large droplets is expected. The role of aggregation was then presented to demonstrate the effects of concentration and type of SPM on the buoyancy of tar balls. Good agreement was found between modeling results and field data reported in the literature regarding the size and density of tar balls. Oil viscosity and mixing energy were found to be the main factors controlling the formation of tar balls. The aggregation of tar balls with SPM and shoreline material results in significant increases or decreases in density, depending on the type and concentration of SPM. 42 refs., 2 tabs., 6 figs.

  10. Charge-Swapping Q-balls

    CERN Document Server

    Copeland, Edmund J; Zhou, Shuang-Yong

    2014-01-01

    Q-balls are non-topological solitonic solutions to a wide class of field theories that possess global symmetries. Here we show that in these same theories there also exists a tower of novel composite Q-ball solutions where, within one composite Q-ball, positive and negative charges co-exist and swap at a frequency lower than the natural frequency of an individual Q-ball. These charge-swapping Q-balls are constructed by assembling Q-balls and anti-Q-balls tightly such that their nonlinear cores overlap. We explain why charge-swapping Q-balls can form and why they swap charges.

  11. Improvements in ball-point pens

    International Nuclear Information System (INIS)

    A method of treating the surface of balls for use in roller ball pens, comprising the operations of placing a plurality of the said balls in a container in an evacuated enclosure, subjecting the balls to bombardment with a beam of ions, and agitating the balls so that the balls are in a state of continuous motion while they are being subjected to ion bombardment. The beam current is passed through the mass of balls by arcing. The beam may be of N+ ions, to increase wear resistance of the surface of the balls which may be of tungsten carbide. (author)

  12. Computing Operating Characteristics Of Bearing/Shaft Systems

    Science.gov (United States)

    Moore, James D.

    1996-01-01

    SHABERTH computer program predicts operating characteristics of bearings in multibearing load-support system. Lubricated and nonlubricated bearings modeled. Calculates loads, torques, temperatures, and fatigue lives of ball and/or roller bearings on single shaft. Provides for analysis of reaction of system to termination of supply of lubricant to bearings and other lubricated mechanical elements. Valuable in design and analysis of shaft/bearing systems. Two versions of SHABERTH available. Cray version (LEW-14860), "Computing Thermal Performances Of Shafts and Bearings". IBM PC version (MFS-28818), written for IBM PC-series and compatible computers running MS-DOS.

  13. Automatic Detection of Steel Ball's Surface Flaws Based on Image Processing

    Institute of Scientific and Technical Information of China (English)

    YU Zheng-lin; TAN Wei; YANG Dong-lin; CAO Guo-hua

    2007-01-01

    A new method to detect steel ball's surface flaws is presented based on computer techniques of image processing and pattern recognition. The steel ball's surface flaws is the primary factor causing bearing failure. The high efficient and precision detections for the surface flaws of steel ball can be conducted by the presented method, including spot, abrasion, burn, scratch and crack, etc. The design of main components of the detecting system is described in detail including automatic feeding mechanism, automatic spreading mechanism of steel ball's surface, optical system of microscope, image acquisition system, image processing system. The whole automatic system is controlled by an industrial control computer, which can carry out the recognition of flaws of steel ball's surface effectively.

  14. Failure analysis of a helicopter's main rotor bearing

    International Nuclear Information System (INIS)

    Presented results report some of the findings of a detailed failure analysis carried out on a main rotor hub assembly, which had symptoms of burning and mechanical damage. The analysis suggests environmental degradation of the grease which causes pitting on bearing-balls. The consequent inefficient lubrication raises the temperature which leads to the smearing of cage material (brass) on the bearing-balls and ultimately causes the failure. The analysis has been supported by the microstructural studies, thermal analysis and micro-hardness testing performed on the affected main rotor bearing parts. (author)

  15. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  16. Enhancing the Bounce of a Ball

    Science.gov (United States)

    Cross, Rod

    2010-01-01

    In sports such as baseball, softball, golf, and tennis, a common objective is to hit the ball as fast or as far as possible. Another common objective is to hit the ball so that it spins as fast as possible, since the trajectory of the ball through the air is strongly affected by ball spin. In an attempt to enhance both the coefficient of…

  17. ES and H-compatible lubrication for duplex bearings

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.G.

    1997-10-01

    Two ES and H-compatible lubricants (environment, safety, and health) for duplex bearing applications and one hybrid material duplex bearing were evaluated and compared against duplex bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in strong link mechanisms since 1974. Hybrid duplex bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, duplex bearings lubricated with sputtered MoS{sub 2} on races and retainers, and duplex bearings lubricated with electrophoretic deposited MoS{sub 2} were evaluated. Bearings with electrophoretic deposited MoS{sub 2} performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax. Hybrid bearings with silicon nitride balls performed worse than bearings lubricated with Vydax, but their performance would still be acceptable for most applications. Bearings lubricated with sputtered MoS{sub 2} on the races and retainers had varying amounts of film on the bearings. This affected the performance of the bearings. Bearings with a uniform coating performed to acceptable levels, but bearings with no visible MoS{sub 2} on the races and retainers did not perform as well as bearings with the other coatings. Unless process controls are incorporated in the sputtering process or the bearings are screened, they do not appear to be acceptable for duplex bearing applications.

  18. Split-ball resonator

    CERN Document Server

    Kuznetsov, Arseniy I; Fu, Yuan Hsing; Viswanathan, Vignesh; Rahmani, Mohsen; Valuckas, Vytautas; Kivshar, Yuri; Pickard, Daniel S; Lukiyanchuk, Boris

    2014-01-01

    We introduce a new concept of split-ball resonator and demonstrate a strong omnidirectional magnetic dipole response for both gold and silver spherical plasmonic nanoparticles with nanometer-scale cuts. Tunability of the magnetic dipole resonance throughout the visible spectral range is demonstrated by a change of the depth and width of the nanoscale cut. We realize this novel concept experimentally by employing the laser-induced transfer method to produce near-perfect spheres and helium ion beam milling to make cuts with the nanometer resolution. Due to high quality of the spherical particle shape, governed by strong surface tension forces during the laser transfer process, and the clean, straight side walls of the cut made by helium ion milling, magnetic resonance is observed at 600 nm in gold and at 565 nm in silver nanoparticles. Structuring arbitrary features on the surface of ideal spherical resonators with nanoscale dimensions provides new ways of engineering hybrid resonant modes and ultra-high near-f...

  19. Ball-joint grounding ring

    Science.gov (United States)

    Aperlo, P. J. A.; Buck, P. A.; Weldon, V. A.

    1981-01-01

    In ball and socket joint where electrical insulator such as polytetrafluoroethylene is used as line to minimize friction, good electrical contact across joint may be needed for lightning protection or to prevent static-charge build-up. Electrical contact is maintained by ring of spring-loaded fingers mounted in socket. It may be useful in industry for cranes, trailers, and other applications requiring ball and socket joint.

  20. Studies On Falling Ball Viscometry

    OpenAIRE

    Singh, Amit Vikram; Sharma, Lavanjay; Gupta-Bhaya, Pinaki

    2012-01-01

    A new method of accurate calculation of the coefficient of viscosity of a test liquid from experimentally measured terminal velocity of a ball falling in the test liquid contained in a narrow tube is described. The calculation requires the value of a multiplicative correction factor to the apparent coefficient of viscosity calculated by substitution of terminal velocity of the falling ball in Stokes formula. This correction factor, the so-called viscosity ratio, a measure of deviation from St...

  1. Vibration analysis of parallel misaligned shaft with ball bearing system

    OpenAIRE

    PSS.Srinivasan; Vaggeeram Hariharan

    2011-01-01

    Misalignment is the most common cause of machine vibration. In this paper, experimental studies were performed ona rotor dynamic test apparatus to predict the vibration spectrum for shaft misalignment. A self-designed simplified 3–pin typeflexible coupling was used in the experiments. Vibration accelerations were measured using dual channel vibration analyzerfor baseline and the misalignment condition. The experimental and numerical frequency spectra were obtained. The experimentalpredictions...

  2. Vibration analysis of parallel misaligned shaft with ball bearing system

    Directory of Open Access Journals (Sweden)

    PSS.Srinivasan

    2011-02-01

    Full Text Available Misalignment is the most common cause of machine vibration. In this paper, experimental studies were performed ona rotor dynamic test apparatus to predict the vibration spectrum for shaft misalignment. A self-designed simplified 3–pin typeflexible coupling was used in the experiments. Vibration accelerations were measured using dual channel vibration analyzerfor baseline and the misalignment condition. The experimental and numerical frequency spectra were obtained. The experimentalpredictions are in good agreement with the numerical results. Both the vibration spectra show that misalignment canbe characterized primarily by 2X shaft running speed. However, misalignment is not close enough to one of the systemnatural frequency to excite the system appreciably. Therefore, in some case the misalignment response is hidden and doesnot show up in the vibration spectrum. The misalignment effect can be amplified, and a high acceleration level at 2X shaftsrunning speed is pronounced in the frequency spectrum.

  3. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    A technique involving a small ball with a transmitter embedded inside it has been successfully tested in Sector 7-8. The ball is sent through the LHC beam pipes to check the LHC interconnections. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI). During the tests the ball is inserted very carefully into the vacuum chamber.A game of ping-pong at the LHC? On 13 September a rather unusual test was carried out in Sector 7-8 of the accelerator. A ball just a bit smaller than a ping-pong ball was carefully introduced into one of the accelerator’s two vacuum pipes, where it travelled 800 metres in the space of a few mi...

  4. Finite Element Analysis of Squirrel Cage Ball Bearingsfor Gas Turbine Engines

    Directory of Open Access Journals (Sweden)

    Benny George

    2007-03-01

    Full Text Available Squirrel cage ball bearings are used in recent aero engines to overcome the vibration andstability problems associated with rotor systems supported by conventional bearings. The criticaldesign feature of squirrel cage bearing is to provide flexible support to rotor system. The outerring of the bearing is configured such that it acts as a flexible bearing support, and hence, weightis minimised. The bearing is mounted directly on a rigid intermediate casing of a gas turbineengine. Finite element analysis helps to obtain a suitable geometry at the design stage. A 3-Dmodel of the bearing is created using IDEAS software. Finite element analysis using contactelement has been carried out for finding the deformation and stresses in the webs at variouslocations using ANSYS software. The deformations are compared with those of experimentalvalues for an axial load. The deformation in the webs is used to check the pressure balance inthe compressor and the load acting on the bearing. Finally, a procedure for doing the finiteelement analysis of ball bearings for combined axial and radial load is laid down.

  5. Isotropic etching technique for three-dimensional microball-bearing raceways

    International Nuclear Information System (INIS)

    A multi-step plasma etching technique is developed to obtain deep-grooved micro-scale ball-bearing raceways and employed in the fabrication of multiple ball-bearing supported microturbines. Deep-groove geometry has been chosen for the microball-bearing systems because of the ability to handle mixed axial and radial loads, allowing for stable, high-speed operation compared to previous iterations of the microball-bearing raceways. The multi-step inductively coupled plasma-based process is optimized to obtain <2% deviation amongst intended raceway depth, width and curvature. Etching non-uniformity is measured to be 0.15% within the raceway of a single device. The bearing dynamics with the new deep-groove geometry have been simulated. The deep-groove raceway packed with off-the-shelf precision ball-bearings provided a stability improvement over previous demonstrations of high-performance rotary micromachines operating at high speeds. (paper)

  6. Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

    Science.gov (United States)

    Halminen, Oskari; Kärkkäinen, Antti; Sopanen, Jussi; Mikkola, Aki

    2015-01-01

    Active magnetic bearings (AMB) offer considerable benefits compared to regular mechanical bearings. On the other hand, they require backup bearings to avoid damage resulting from a failure in the component itself, or in the power or control system. During a rotor-bearing contact event - when the magnetic field has disappeared and the rotor drops on the backup bearings - the structure of the backup bearings has an impact on the dynamic actions of the rotor. In this paper, the dynamics of an active magnetic bearing-supported rotor during contact with backup bearings is studied with a simulation model. Modeling of the backup bearings is done using a comprehensive cageless ball bearing model. The elasticity of the rotor is described using the finite element method (FEM) and the degrees of freedom (DOF) of the system are reduced using component mode synthesis. Verification of the misaligned cageless backup bearings model is done by comparing the simulation results against the measurement results. The verified model with misaligned cageless backup bearings is found to correspond to the features of a real system.

  7. MIPP Plastic Ball electronics upgrade

    International Nuclear Information System (INIS)

    An upgrade electronics design for Plastic Ball detector is described. The Plastic Ball detector was a part of several experiments in the past and its back portion (proposed to be used in MIPP) consists of 340 photomultipliers equipped with a sandwich scintillator. The scintillator sandwich has fast and slow signal component with decay times 10 ns and 1 (micro)s respectively. The upgraded MIPP experiment will collect up to 12,000 events during each 4 second spill and read them out in ∼50 seconds between spills. The MIPP data acquisition system will employ deadtime-less concept successfully implemented in Muon Electronics of Dzero experiment at Fermilab. An 8-channel prototype design of the Plastic Ball Front End (PBFE) implementing these requirements is discussed. Details of the schematic design, simulation and prototype test results are discussed.

  8. MIPP Plastic Ball electronics upgrade

    International Nuclear Information System (INIS)

    An upgrade electronics design for Plastic Ball detector is described. The Plastic Ball detector was a part of several experiments in the past and its back portion (proposed to be used in Main Injector Particle Production (MIPP)) consists of 340 photomultipliers equipped with a sandwich scintillator. The scintillator sandwich has fast and slow signal component with decay times 10 ns and 1 μs, respectively. The upgraded MIPP experiment will collect up to 12,000 events during each 4 s spill and read them out in ∼50 s between spills. The MIPP data acquisition system will employ deadtime-less concept successfully implemented in Muon Electronics of Dzero experiment at Fermilab An 8-channel prototype design of the Plastic Ball Front-End (PBFE) implementing these requirements is discussed. Details of the schematic design, simulation and prototype test results are discussed.

  9. Berkeley High-Resolution Ball

    International Nuclear Information System (INIS)

    Criteria for a high-resolution γ-ray system are discussed. Desirable properties are high resolution, good response function, and moderate solid angle so as to achieve not only double- but triple-coincidences with good statistics. The Berkeley High-Resolution Ball involved the first use of bismuth germanate (BGO) for anti-Compton shield for Ge detectors. The resulting compact shield permitted rather close packing of 21 detectors around a target. In addition, a small central BGO ball gives the total γ-ray energy and multiplicity, as well as the angular pattern of the γ rays. The 21-detector array is nearly complete, and the central ball has been designed, but not yet constructed. First results taken with 9 detector modules are shown for the nucleus 156Er. The complex decay scheme indicates a transition from collective rotation (prolate shape) to single- particle states (possibly oblate) near spin 30 h, and has other interesting features

  10. Hydraulic-Ball (HY-Ball) Control System

    International Nuclear Information System (INIS)

    The Hy-Ball control system consists of a large number of small tubes vertically penetrating the active core region; the tubes contain movable poison elements (either spherical or cylindrical), which are hydraulically lifted upward from within the active core region to increase core reactivity. Reactor water is the actuating fluid. Hy-Ball columns occupy fuel-element lattice positions in a homogeneous fuel-element configuration. This configuration, with finely subdivided control elements, practically eliminates local water-hole power peaking and provides good control of the radial power distribution. By limitation of the amount of reactivity controlled by a single Hy-Ball column assembly to 0.1% or less, it is unnecessary to operate the poison elements in any position other than either the fully-inserted or fully-withdrawn positions. Elimination of intermediate positions results in simplicity of the system and avoids the inherent axial power perturbation resulting from partially inserted control elements. Physics studies indicate that up to about 40% more power can be obtained from a Hy-Ball-controlled core than from a core with conventional control rods. Tests simulating all reactor operating conditions except radiation are being performed for evaluation of costs, operational characteristics and long-term reliability effects. (author)

  11. Rotordynamics and bearing design of turbochargers

    Science.gov (United States)

    Chen, Wen Jeng

    2012-05-01

    Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

  12. Aligner for Elastic Collisions of Dropped Balls.

    Science.gov (United States)

    Mellen, Walter Roy

    1995-01-01

    Discusses an aligner that permits dropping a stack of any number of balls of different sizes, elasticities, hardnesses, or types to observe the rebound of the top ball. Experimental results allow a reasonable comparison with theory. (MVL)

  13. Plutonium destruction with pebble bed type HTGRs using Pu burner balls and breeder balls

    International Nuclear Information System (INIS)

    It was made clear that pebble bed type HTGRs using Pu burner balls (pu balls) and breeder balls (Th balls) possesses a potential to burn weapons-grade Pu to 740 Gwd/TPu. The total amounts of Pu and 239Pu of can reduced to about 20 and 1%, respectively. (author). 10 refs, 4 figs, 2 tabs

  14. Laboratory-produced ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1994-05-01

    For 25 years I have actively been searching for the true nature of ball lightning and attempting to reproduce it at will in the laboratory. As one might expect, many unidentified lights in the atmosphere have been called ball lightning, including Texas Maffa lights (automobile headlights), flying saucers (UFOs), swamp gas in Ann Arbor, Michigan, etc. For 15 years I thought ball lightning was strictly a high-voltage phenomenon. It was not until 1984 when I was short-circuiting the electrical output of a diesel electric railroad locomotive that I realized that the phenomenon was related more to a high current. Although I am hoping for some other types of ball lightning to emerge such as strictly electrostatic-electromagnetic manifestations, I have been unlucky in finding laboratory provable evidence. Cavity-formed plasmodes can be made by putting a 2-inch burning candle in a home kitchen microwave oven. The plasmodes float around for as long as the microwave energy is present.

  15. A Conjecture Concerning Ball Lightning

    CERN Document Server

    Sturrock, P A

    2016-01-01

    There is at present no theory that can explain the curious properties of ball lightning. This suggests that we may not be using the most appropriate concepts. The concept of a 'parallel space' may point the way to a valid theory.

  16. Generation of Laboratory Ball Lightning

    International Nuclear Information System (INIS)

    The phenomenon of energy conversion in the streams of directed electrons and ions into electromagnetic radiation was found out experimentally and proved theoretically. The direct proofs of the domain mechanism of the charged particles acceleration and mechanism of ball lightning generation were obtained and the theoretical calculations were refined

  17. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    1. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI).2. During the tests the ball is inserted very carefully into the vacuum chamber.1. Le groupe pluridisciplinaire qui a mené le projet de balle RF pour vérifier les interconnexions avec, de gauche à droite, Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS) et Marek Gasior (AB/BI).2. Lors des tests, la balle est insérée dans la chambre à vide avec beaucoup de précaution.

  18. SECRET OF A BALL LIGHTNING

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-04-01

    Full Text Available A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming, in the end, the surrounding air into a steam cloud that transits into ferroelectric state under the magnetic field action.

  19. Secrets of the Crystal Ball

    Science.gov (United States)

    Croucher, John S.

    2007-01-01

    This article describes how a crystal ball known as "The Flash Mind Reader" is played. "The Flash Mind Reader" is a mathematics game in which the player is invited to select any-two digit number and then subtract the sum of these two digits from the original number. A chart is provided in which the (adjusted) number they obtained will have a symbol…

  20. Wind Turbine Design Guideline DG03: Yaw and Pitch Rolling Bearing Life

    Energy Technology Data Exchange (ETDEWEB)

    Harris, T.; Rumbarger, J. H.; Butterfield, C. P.

    2009-12-01

    This report describes the design criteria, calculation methods, and applicable standards recommended for use in performance and life analyses of ball and roller (rolling) bearings for yaw and pitch motion support in wind turbine applications. The formulae presented here for rolling bearing analytical methods and bearing-life ratings are consistent with methods in current use by wind turbine designers and rolling-bearing manufacturers.

  1. Software Developed for Analyzing High- Speed Rolling-Element Bearings

    Science.gov (United States)

    Fleming, David P.

    2005-01-01

    COBRA-AHS (Computer Optimized Ball & Roller Bearing Analysis--Advanced High Speed, J.V. Poplawski & Associates, Bethlehem, PA) is used for the design and analysis of rolling element bearings operating at high speeds under complex mechanical and thermal loading. The code estimates bearing fatigue life by calculating three-dimensional subsurface stress fields developed within the bearing raceways. It provides a state-of-the-art interactive design environment for bearing engineers within a single easy-to-use design-analysis package. The code analyzes flexible or rigid shaft systems containing up to five bearings acted upon by radial, thrust, and moment loads in 5 degrees of freedom. Bearing types include high-speed ball, cylindrical roller, and tapered roller bearings. COBRA-AHS is the first major upgrade in 30 years of such commercially available bearing software. The upgrade was developed under a Small Business Innovation Research contract from the NASA Glenn Research Center, and incorporates the results of 30 years of NASA and industry bearing research and technology.

  2. Aerodynamics of a golf ball with grooves

    Science.gov (United States)

    Kim, Jooha; Son, Kwangmin; Choi, Haecheon

    2009-11-01

    It is well known that the drag on a dimpled ball is much lower than that on smooth ball. Choi et al. (Phys. Fluids, 2006) showed that turbulence is generated through the instability of shear layer separating from the edge of dimples and delays flow separation. Based on this mechanism, we devise a new golf ball with grooves on the surface but without any dimples. To investigate the aerodynamic performance of this new golf ball, an experiment is conducted in a wind tunnel at the Reynolds numbers of 0.5 x10^5 - 2.7 x10^5 and the spin ratios (ratio of surface velocity to the free-stream velocity) of α=0 - 0.5, which are within the ranges of real golf-ball velocity and spin rate. We measure the drag and lift forces on the grooved ball and compare them with those of smooth ball. At zero spin, the drag coefficient on the grooved ball shows a rapid fall-off at a critical Reynolds number and maintains a minimum value which is lower by 50% than that on smooth ball. At non-zero α, the drag coefficient on the grooved ball increases with increasing α, but is still lower by 40% than that on smooth ball. The lift coefficient on the grooved ball increases with increasing α, and is 100% larger than that on smooth ball. The aerodynamic characteristics of grooved ball is in general quite similar to that of dimpled ball. Some more details will be discussed in the presentation.

  3. Development and Evaluation of Titanium Space Suit Bearings

    Science.gov (United States)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Ray, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z series space suit architecture allows us to reduce mass by an estimated 23 pounds per suit system compared to the previously used stainless steel bearing designs without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race: 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approximately 2 years), bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination around a maximum contact stress that will allow the bearing to survive the life of an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an exploration mission.

  4. Analysis of coolant flow and heat transfer in the SSME HPOTP Number 4 bearing assembly

    Science.gov (United States)

    Owens, S. F.; Costes, N. C.

    1990-01-01

    The PHOENICS code has been applied to simulate the flow of liquid oxygen through the number 4 ball bearing assembly of the Space Shuttle Main Engine High-Pressure Oxidizer Turbopump. The Body-Fitted Coordinate system capability of PHOENICS was utilized to create a geometrically accurate model. Effects accounted for by the model include the rotation rate of the calculation domain, viscous heating in the liquid oxygen and two-phase effects due to LOX boiling. A separation program was used to account for conduction within a ball bearing element which was coupled with the PHOENICS flow and heat transfer analysis. Solutions have been obtained for the velocity and temperature fields within the LOX coolant and the temperature within the ball element. The predicted ball temperatures indicate that the coolant is boiling in the region near the ball surface.

  5. Ball Nut Preload Diagnosis of the Hollow Ball Screw through Sensed Current Signals

    Directory of Open Access Journals (Sweden)

    Yi-Cheng Huang

    2014-08-01

    Full Text Available This paper studies the diagnostic results of hollow ball screws with different ball nut preload levels through the Hilbert-Huang transform (HHT and multiscale entropy (MSE process. The method is tested using ball screw pretension and an oil cooling circulation system. MSE was used to determine the hollow ball screw preload status through the servo motor current signals. Ball screws with maximum dynamic preloads of 2%, 4%, and 6% were predesigned, manufactured, and tested. Signal patterns are discussed and revealed by the Hilbert Spectrum. Different preload features are extracted using HHT and MSE. The irregularity development of the ball screw driving motion current can be discriminated and abstracted via MSE based on complexity perception. Experimental results show that the proposed approach can successfully predict the prognostic status of ball nut preload. A comparative evaluation of MSE allows for smart sensing for the health of the ball screw. This method effectively diagnoses the ball nut preload status.

  6. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  7. Exact Wavelets on the Ball

    CERN Document Server

    Leistedt, B

    2012-01-01

    We develop an exact wavelet transform on the three-dimensional ball (i.e. on the solid sphere), which we name the flaglet transform. For this purpose we first construct an exact harmonic transform on the radial line using damped Laguerre polynomials and develop a corresponding quadrature rule. Combined with the spherical harmonic transform, this approach leads to a sampling theorem on the ball and a novel three-dimensional decomposition which we call the Fourier-Laguerre transform. We relate this new transform to the well-known Fourier-Bessel decomposition and show that band-limitness in the Fourier-Laguerre basis is a sufficient condition to compute the Fourier-Bessel decomposition exactly. We then construct the flaglet transform on the ball through a harmonic tiling, which is exact thanks to the exactness of the Fourier-Laguerre transform (from which the name flaglets is coined). The corresponding wavelet kernels have compact localisation properties in real and harmonic space and their angular aperture is i...

  8. Studies On Falling Ball Viscometry

    CERN Document Server

    Singh, Amit Vikram; Gupta-Bhaya, Pinaki

    2012-01-01

    A new method of accurate calculation of the coefficient of viscosity of a test liquid from experimentally measured terminal velocity of a ball falling in the test liquid contained in a narrow tube is described. The calculation requires the value of a multiplicative correction factor to the apparent coefficient of viscosity calculated by substitution of terminal velocity of the falling ball in Stokes formula. This correction factor, the so-called viscosity ratio, a measure of deviation from Stokes limit, arises from non-vanishing values of the Reynolds number and the ball/tube radius ratio. The method, valid over a very wide range of Reynolds number, is based on the recognition of a relationship between two measures of wall effect, the more widely investigated velocity ratio, defined as the ratio of terminal velocity in a confined medium to that in a boundless medium and viscosity ratio. The calculation uses two recently published correlation formulae based on extensive experimental results on terminal velocit...

  9. Ball Screw Actuator Including a Stop with an Integral Guide

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  10. Robotic Arm-The Ball Catcher

    Directory of Open Access Journals (Sweden)

    J.C.Titarmare

    2014-02-01

    Full Text Available Catching a thrown ball with a hand is not easy – neither for humans nor for robots. It demands for a tight interplay of skills in mechanics, control, planning and visual sensing to reach the necessary precision in space and time. Because of this, ball catching has been used for almost 20 years now as a challenging benchmark system to develop and test robotics key technologies. Here we propose a high speed and intelligent robotic arm set up which will capable enough to catch the short range thrown ball in specified environment. The main technique used is a stereo vision system to tracks the ball and predicts the balls trajectory then the point and time required to reach at destination point, and in which orientation the robot should intercept the ball on its trajectory, is determined. Once robots calculate the desired parameters it will try to catch the ball. Expected outcome of the proposed system is to catch the ball by calculating the coming ball path using computer vision techniques and move the robotic arm in order to catch the ball

  11. Bearing structures

    International Nuclear Information System (INIS)

    A hydrostatic bearing for the lower end of the vertical shaft of a sodium pump comprises a support shell encircling the shaft and a bush located between the shell and shaft. Liquid sodium is fed from the pump outlet to the bush/shaft and bush/shell interfaces to provide hydrostatic support. The bush outer surface and the shell inner surface are of complementary part-spherical shape and the bush floats relative to the shaft so that the bush can align itself with the shaft axis. Monitoring of the relative rotational speed of the bush with respect to the shaft (such rotation being induced by the viscous drag forces present) is also performed for the purposes of detecting abnormal operation of the bearing or partial seizure, at least one magnet is rotatable with the bush, and a magnetic sensor provides an output having a frequency related to the speed of the bush. (author)

  12. Adiabatic Invariance of Oscillons/I-balls

    CERN Document Server

    Kawasaki, Masahiro; Takeda, Naoyuki

    2015-01-01

    Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or $I$-balls. We prove the adiabatic invariance of the oscillons/$I$-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/$I$-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/$I$-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the $I$-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/$I$-balls is due to the adiabatic invariance.

  13. Tooling Converts Stock Bearings To Custom Bearings

    Science.gov (United States)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  14. Improvement of Dynamic Performance of Hybrid Gas Bearings via Adjustable Lubrication

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

    2013-01-01

    and the pressure and velocity fields in the injection nozzle are compared. The simplified theoretical model has been validated against the CFD results and experimentally using a test rig. The test rig consists of a flexible rotor supported by a ball bearing and a controllable hybrid gas bearing. The results show...

  15. Multifractal properties of ball milling dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Budroni, M. A., E-mail: mabudroni@uniss.it; Pilosu, V.; Rustici, M. [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, Via Vienna 2, Sassari 07100 (Italy); Delogu, F. [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, Cagliari 09123 (Italy)

    2014-06-15

    This work focuses on the dynamics of a ball inside the reactor of a ball mill. We show that the distribution of collisions at the reactor walls exhibits multifractal properties in a wide region of the parameter space defining the geometrical characteristics of the reactor and the collision elasticity. This feature points to the presence of restricted self-organized zones of the reactor walls where the ball preferentially collides and the mechanical energy is mainly dissipated.

  16. From Schwinger Balls to Curved Space

    CERN Document Server

    Allahbakhshi, Davood

    2016-01-01

    It is shown that the Reissner-Nordstrom black hole is also a gravitational Schwinger ball. It is also shown that both massless and massive-particle gravitational Schwinger balls are thermodynamic systems by deriving the first law of thermodynamics for them. Inconsistency between classical geometrical and microscopic definitions of the horizon is discussed. We propose a new metric, more consistent with microscopic picture of black hole, as gravitational Schwinger ball, by speculations. It has some interesting features.

  17. The plasma theory of ball lightning

    International Nuclear Information System (INIS)

    The high-energy density inside the ball lightning is due to existence of in ntense plasma oscillations and high kinetic and potential energy of electron gas which form a pulsating ball vibrating relative to the nearly stationary ionic ba all. At sublight velocities of electrons one can neglect the processes of their scattering and recombination. One obtains a relation between parameters of the plasma ball from the condition of equally of excess pressure of ions and that o Madelung forces. The high lifetime of the ball lighting is connected with smal ll Landau damping for the longest wave vibrations

  18. Coefficient of Restitution of Wet Tennis Balls

    OpenAIRE

    Eugene Jang; Tony Kim

    2014-01-01

    The coefficient of restitution of a damp tennis ball is of interest to tennis players. Using a spray bottle, water was added to a tennis ball and the mass of water on the wet ball was determined. The ball was then dropped from a fixed height of 0.86 m. The motion was recorded with a video camera and the bounce height was measured. Using the bounce height and the original height, the coefficient of restitution for that mass of added water was determined. The research found the mass of wa...

  19. A study on real-time fault monitoring detection method of bearing using the infrared thermography

    International Nuclear Information System (INIS)

    Since real-time monitoring system like a fault early detection has been very important, infrared thermography technique as a new diagnosis method was proposed. This study is focused on the damage detection and temperature characteristic analysis of ball bearing using the non-destructive infrared thermography method. In this paper, for the reliability assessment, infrared experimental data were compared with the frequency data of the existing. As results, the temperature characteristics of ball bearing were analyzed under various loading conditions. Finally it was confirmed that the infrared technique was useful for real-time detection of the bearing damages.

  20. Rolling Friction Torque in Ball-Race Contacts Operating in Mixed Lubrication Conditions

    Directory of Open Access Journals (Sweden)

    Mihaela Rodica D. Bălan

    2015-04-01

    Full Text Available Based on a theoretical model and an experimental methodology for defining the friction torque for lubricated conditions in a modified thrust ball bearing having only three balls, the authors experimentally investigated the influence of the lubricant parameter Λ on friction torque for mixed IVR (isoviscous rigid and EHL (elastohydrodynamic lubrication conditions. The experiments were conducted using ball diameters of 3 mm, 3.97 mm and 6.35 mm loaded at 0.125 N, 0.400 N and 0.633 N. Two oils of viscosity 0.08 Pa·s and 0.05 Pa·s were used and rotational speed was varied in the range 60–210 rpm to obtain a lubricant parameter Λ varying between 0.3 and 3.2. The experiments confirmed that the measured friction torque can be explained using hydrodynamic rolling force relationships respecting the transition from an IVR to an EHL lubrication regime.

  1. Mechanical design problems associated with turbopump fluid film bearings

    Science.gov (United States)

    Evces, Charles R.

    1990-01-01

    Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

  2. Structural and dynamical properties of Yukawa balls

    International Nuclear Information System (INIS)

    To study the structural and dynamical properties of finite 3D dust clouds (Yukawa balls) new diagnostic tools have been developed. This contribution describes the progress towards 3D diagnostics for measuring the particle positions. It is shown that these diagnostics are capable of investigating the structural and dynamical properties of Yukawa balls and gaining insight into their basic construction principles

  3. Fusion characteristics of ball lighting like configurations

    International Nuclear Information System (INIS)

    Assuming that an already proposed self-organization physical scenario is at the origin of both ball lightnings as well as fireballs produced in high intensity electrical discharges, we suggest a new possibility to create fusion relevant ball lightning like configurations in laboratory. Perhaps this becomes possible by prolonging in a controllable way their lifetime and energy content. (author)

  4. Phenomenon of ball lightning and its outgrowths

    International Nuclear Information System (INIS)

    New physical phenomena deduced from properties of ball lightning are considered under assumption that ball lightning is a light bubble comprising of a thin spherical layer of compressed air where an intense light circulates in all possible directions. Explanation of behavior of autonomous luminous objects produced at gas discharge is presented

  5. Are perytons signatures of ball lighting?

    CERN Document Server

    Dodin, I Y

    2014-01-01

    The enigmatic downchirped signals, called "perytons", that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning. Although this is still a hypothesis, the parallels between perytons and ball lightning are striking.

  6. Some Mathematics and Physics of Ball Games.

    Science.gov (United States)

    Hughes, D. E.

    1985-01-01

    Gives examples on the applications of arithmetic, geometry, and some calculus, vector algebra, and mechanics to ball games. Suggestions for further interesting investigations are provided together with references to other articles and books on applications of mathematics and physics to ball games and sports in general. (JN)

  7. Decomposition of balls in R^d

    OpenAIRE

    Kiss, Gergely; Somlai, Gabor

    2016-01-01

    We investigate the decomposition problem of balls into finitely many congruent pieces in dimension d = 2k. In addition, we prove that the d dimensional unit ball B_d can be divided into finitely many congruent pieces if d = 4 or d ≥ 6. We show that the minimal number of required pieces is less than 20d if d ≥ 10.

  8. Coefficient of Restitution of a Tennis Ball

    Directory of Open Access Journals (Sweden)

    Andre Roux

    2007-06-01

    Full Text Available The coefficient of restitution (COR of a tennis ball was investigated over a range of impact velocities. It was found that the COR of the ball was lower than ATP regulations specify, and that the COR decreased with increasing impact velocity.

  9. Coefficient of Restitution of a Tennis Ball

    OpenAIRE

    Andre Roux; Jennifer Dickerson

    2007-01-01

    The coefficient of restitution (COR) of a tennis ball was investigated over a range of impact velocities. It was found that the COR of the ball was lower than ATP regulations specify, and that the COR decreased with increasing impact velocity.

  10. Flicker Ball, Physical Education: 5551.34.

    Science.gov (United States)

    Stout, Paul L.

    This course outline is a guide for teaching skills of flicker ball in grades 7-12. The course format includes lectures, game situations, class tournaments, and tests that focus on mastery of skills, understanding of rules, and development of techniques in shooting and passing. Course content includes the following: (a) history of flicker ball, (b)…

  11. Soccer Ball Lift Coefficients via Trajectory Analysis

    Science.gov (United States)

    Goff, John Eric; Carre, Matt J.

    2010-01-01

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…

  12. Surface modification of titanium using steel slag ball and shot blasting treatment for biomedical implant applications

    Science.gov (United States)

    Arifvianto, Budi; Suyitno; Mahardika, Muslim

    2013-08-01

    Surface modification is often performed using grit or shot blasting treatment for improving the performances of biomedical implants. The effects of blasting treatments using steel slag balls and spherical shots on the surface and subsurface of titanium were studied in this paper. The treatments were conducted for 60-300 s using 2-5 mm steel slag balls and 3.18 mm spherical shots. The surface morphology, roughness, and elemental composition of titanium specimens were examined prior to and after the treatments. Irregular and rough titanium surfaces were formed after the treatment with the steel slag balls instead of the spherical shots. The former treatment also introduced some bioactive elements on the titanium surface, but the latter one yielded a harder surface layer. In conclusion, both steel slag ball and shot blasting treatment have their own specialization in modifying the surface of metallic biomaterials. Steel slag ball blasting is potential for improving the osseointegration quality of implants; but the shot blasting is more appropriate for improving the mechanical properties of temporary and load bearing implants, such as osteosynthesis plates.

  13. Self-dispersed crumpled graphene balls in oil for friction and wear reduction.

    Science.gov (United States)

    Dou, Xuan; Koltonow, Andrew R; He, Xingliang; Jang, Hee Dong; Wang, Qian; Chung, Yip-Wah; Huang, Jiaxing

    2016-02-01

    Ultrafine particles are often used as lubricant additives because they are capable of entering tribological contacts to reduce friction and protect surfaces from wear. They tend to be more stable than molecular additives under high thermal and mechanical stresses during rubbing. It is highly desirable for these particles to remain well dispersed in oil without relying on molecular ligands. Borrowing from the analogy that pieces of paper that are crumpled do not readily stick to each other (unlike flat sheets), we expect that ultrafine particles resembling miniaturized crumpled paper balls should self-disperse in oil and could act like nanoscale ball bearings to reduce friction and wear. Here we report the use of crumpled graphene balls as a high-performance additive that can significantly improve the lubrication properties of polyalphaolefin base oil. The tribological performance of crumpled graphene balls is only weakly dependent on their concentration in oil and readily exceeds that of other carbon additives such as graphite, reduced graphene oxide, and carbon black. Notably, polyalphaolefin base oil with only 0.01-0.1 wt % of crumpled graphene balls outperforms a fully formulated commercial lubricant in terms of friction and wear reduction. PMID:26811466

  14. A model for ball lightning

    International Nuclear Information System (INIS)

    A model for ball lightning (BL) is described. It is based upon the vorton model for elementary particles, which exploits the symmetry between electricity and magnetism. The core, or driving engine, of BL in this model is comprised of a vorton-antivorton plasma. The energy of BL, which derives from nucleon decay catalyzed by this plasma, leads, through various mechanisms, to BL luminosity as well as to other BL features. It is argued that this model could also be a suitable explanation for other luminous phenomena, such as the unidentified atmospheric light phenomena seen at Hessdalen. It is predicted that BL and similar atmospheric luminous phenomena should manifest certain features unique to this model, which would be observable with suitable instrumentation

  15. La balle et la plume

    Directory of Open Access Journals (Sweden)

    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  16. Application of space technology to X-ray tube bearings

    Energy Technology Data Exchange (ETDEWEB)

    Ring, P.J. [Advanced Methods and Materials Co., San Jose, CA (United States); Virshup, G.F. [Varian Associates, Palo Alto, CA (United States)

    1996-12-31

    This paper describes work done to transfer technology, developed during the SP100 Space Reactor program, to commercial applications. The SP100 program was intended to develop a high temperature nuclear reactor power source for space applications. The specific area described in this paper is the use of high temperature bearings and lubricants under vacuum conditions. At the instigation of the Jet Propulsion Laboratory, a joint program was initiated between Varian Corporation and Advanced Methods and Materials Co. (AMM); with AMM providing the technical expertise in high temperature bearing technology, acquired during the Sp100 program, and Varian providing the testing and performance evaluation of the completed bearing assemblies. The Varian bearing application is X-ray tubes. The tungsten target is required to rotate within the vacuum tube with the bearings operating at temperatures in the region of 300 C. The high temperature vacuum conditions preclude the use of any organic lubricants. The desired improvements in bearing performance were in the areas of noise reduction and extended lifetime. The SP100 program had required low friction ball bearings for the Control Drive Assembly motors, clutches and brakes. These assemblies were required to operate at 540 C in hard vacuum. For the SP100 program silver coated tool steel bearings were tested along with molybdenum disulfide coated Stellite L605 races and balls with molybdenum disulfide coated Stellite L605 races with silicon nitride balls. The work described in this paper covers the results from the SP100 tests and describes the application of this technology to the Varian X-ray tubes using optimized MoS{sub 2} deposition parameters. The results of this work to date and the conclusions resulting from the endurance testing are described in detail.

  17. Friction and wear of HPSN bearing materials

    International Nuclear Information System (INIS)

    Silicon nitride-based ceramics are used as high-performance materials for roller bearings. Its low specific gravity (about one-third that of ball-bearing steel), retention of strength at high temperature and corrosion resistance make Si3N4 ideal for this application. The first study of hot-pressed silicon nitride (HPSN) was made by Baumgartner. Later works were reviewed by Cranmer. Most previous work was related to the evaluation of HPSN in contact with itself. In this paper, the authors present work on wear and friction of HPSN and its composites in contact with ball-bearing steel. HPSN was made by sintering a nitrogen-rich Si3N4 liquid phase. The effect of sintering aids on the wear behavior of HPSN and its composites was investigated. The composites were made by adding either a high-temperature lubricating material, e.g., hexagonal boron nitride (BN) or harder particulates, e.g., titanium carbide (TiC)

  18. Viscoelastic modelling of tennis ball properties

    International Nuclear Information System (INIS)

    An explicit finite element (FE) tennis ball model which illustrates the effects of the viscoelastic materials of a tennis ball on ball deformation and bounce during normal impacts is presented. A tennis ball is composed of a rubber core and a fabric cover comprised of a wool-nylon mix which exhibit non-linear strain rate properties during high velocity impacts. The rubber core model was developed and validated using low strain rate tensile tests on rubber samples as well as high velocity normal impacts of pressurised cores at velocities ranging from 15 m/s to 50 m/s. The impacts were recorded using a high speed video (HSV) camera to determine deformation, impact time and coefficient of restitution (COR). The material properties of the core model were tuned to match the HSV results. A two component anisotropic fabric model was created which included artificial Rayleigh damping to account for hysteresis effects, and the core model 'tuning' process was used to refine the cloth layer. The ball model's parameters were in good agreement with experimental data at all velocities for both cores and complete balls, and a time sequenced comparison of HSV ball motion and FE model confirmed the validity of the model.

  19. BALL - biochemical algorithms library 1.3

    Directory of Open Access Journals (Sweden)

    Stöckel Daniel

    2010-10-01

    Full Text Available Abstract Background The Biochemical Algorithms Library (BALL is a comprehensive rapid application development framework for structural bioinformatics. It provides an extensive C++ class library of data structures and algorithms for molecular modeling and structural bioinformatics. Using BALL as a programming toolbox does not only allow to greatly reduce application development times but also helps in ensuring stability and correctness by avoiding the error-prone reimplementation of complex algorithms and replacing them with calls into the library that has been well-tested by a large number of developers. In the ten years since its original publication, BALL has seen a substantial increase in functionality and numerous other improvements. Results Here, we discuss BALL's current functionality and highlight the key additions and improvements: support for additional file formats, molecular edit-functionality, new molecular mechanics force fields, novel energy minimization techniques, docking algorithms, and support for cheminformatics. Conclusions BALL is available for all major operating systems, including Linux, Windows, and MacOS X. It is available free of charge under the Lesser GNU Public License (LPGL. Parts of the code are distributed under the GNU Public License (GPL. BALL is available as source code and binary packages from the project web site at http://www.ball-project.org. Recently, it has been accepted into the debian project; integration into further distributions is currently pursued.

  20. Numerical simulation of ball-racket impact

    Science.gov (United States)

    Yu, Yingpang

    The collision of a ball with a tennis racket is usually modeled in terms of rigid body dynamics or an elastic system involving only a few springs. In this paper, we study the impact between a tennis ball and racket, by modeling the tennis ball in two different yaws. One method models the tennis ball as a Hertz elastic body and the other one models the ball by a more accurate finite element analysis. In the first model, we assume that the elastic properties of the ball obeys Hertz's law. In the finite element model, we consider the tennis ball as a shell witch is a elastic system constructed out of many isotropic small linear flat, elements, witch have both elastic and damping properties. The damping in each way is approximated as viscous term. In both methods, we study the static condition of deformation against a rigid surface before applying these models to dynamical processes. We compare these two methods and eventually determine how the racket parameters effect the performance of the racket, using numerical simulations. Comparison with experiment are show to confirm the general conclusion of the model.

  1. Gravitational Waves from Q-ball Formation

    CERN Document Server

    Chiba, Takeshi; Yamaguchi, Masahide

    2009-01-01

    We study the detectability of the gravitational waves (GWs) from the Q-ball formation associated with the Affleck-Dine (AD) mechanism, taking into account both of the dilution effect due to Q-ball domination and of finite temperature effects. The AD mechanism predicts the formation of non-topological solitons, Q-balls, from which GWs are generated. Q-balls with large conserved charge $Q$ can produce a large amount of GWs. On the other hand, the decay rate of such Q-balls is so small that they may dominate the energy density of the universe, which implies that GWs are significantly diluted and that their frequencies are redshifted during Q-ball dominated era. Thus, the detectability of the GWs associated with the formation of Q-balls is determined by these two competing effects. We find that there is a finite but small parameter region where such GWs may be detected by future detectors such as DECIGO or BBO, only in the case when the thermal logarithmic potential dominates the potential of the AD field. Otherw...

  2. Viscoelastic modelling of tennis ball properties

    Science.gov (United States)

    Sissler, L.; Jones, R.; Leaney, P. G.; Harland, A.

    2010-06-01

    An explicit finite element (FE) tennis ball model which illustrates the effects of the viscoelastic materials of a tennis ball on ball deformation and bounce during normal impacts is presented. A tennis ball is composed of a rubber core and a fabric cover comprised of a wool-nylon mix which exhibit non-linear strain rate properties during high velocity impacts. The rubber core model was developed and validated using low strain rate tensile tests on rubber samples as well as high velocity normal impacts of pressurised cores at velocities ranging from 15 m/s to 50 m/s. The impacts were recorded using a high speed video (HSV) camera to determine deformation, impact time and coefficient of restitution (COR). The material properties of the core model were tuned to match the HSV results. A two component anisotropic fabric model was created which included artificial Rayleigh damping to account for hysteresis effects, and the core model 'tuning' process was used to refine the cloth layer. The ball model's parameters were in good agreement with experimental data at all velocities for both cores and complete balls, and a time sequenced comparison of HSV ball motion and FE model confirmed the validity of the model.

  3. Craniofacial reconstruction using rational cubic ball curves.

    Directory of Open Access Journals (Sweden)

    Abdul Majeed

    Full Text Available This paper proposes the reconstruction of craniofacial fracture using rational cubic Ball curve. The idea of choosing Ball curve is based on its robustness of computing efficiency over Bezier curve. The main steps are conversion of Digital Imaging and Communications in Medicine (Dicom images to binary images, boundary extraction and corner point detection, Ball curve fitting with genetic algorithm and final solution conversion to Dicom format. The last section illustrates a real case of craniofacial reconstruction using the proposed method which clearly indicates the applicability of this method. A Graphical User Interface (GUI has also been developed for practical application.

  4. Cohesion in ball lightning and cook plasmas

    International Nuclear Information System (INIS)

    The phenomenon of ball lightning has been observed for a long time, but the nature of these luminous balls has been unknown. It is proposed here that they consist of highly excited Rydberg atoms with large polarizabilities. Thus the cohesion of the balls comes from photon exchange forces (London dispersion forces) rather than electron exchange (chemical) forces. The cohesion in plasmas generated at the back faces of detonating explosives (Cook's plasmas) may have a similar basis. Numerical estimates are given to justify these interpretations

  5. Rotating Boson Stars and Q-Balls

    CERN Document Server

    Kleihaus, B; List, M; Kleihaus, Burkhard; Kunz, Jutta; List, Meike

    2005-01-01

    We consider axially symmetric, rotating boson stars. Their flat space limits represent spinning Q-balls. We discuss their properties and determine their domain of existence. Q-balls and boson stars are stationary solutions and exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the boson stars. We address the flat space limit and the limit of strong gravitational coupling. For comparison we also determine the properties of spherically symmetric Q-balls and boson stars.

  6. Dynamic characteristics of hard disk drive spindles supported by hydrodynamic bearings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Most hard disk spindles currently used are supported by grease lubricated deep-groove ball bearings.However, in the trend of increasing spindle speed and reducing size and cost, the shortcomings of ball bearing spin-dles, such as high non-repeatable run out, high acoustic noise and short life time at high running speed, make themunsuitable for high performance hard disk drives (HDD). On the contrary, the dynamic characteristics of hydrody-namic bearing spindles are superior to that of ball bearing spindles. Therefore, they are considered to be the substi-tute of ball bearing spindles in HDD. In this paper, a simulative setup of HDD is build up. The dynamic characteristicsof liquid lubricated spiral groove bearing(SGB) spindles are studied. The effects of both operating condition andbearing clearance are investigated. It is found that running speed of the spindle has significant influence on its dy-namic performance, while the load has little influence. The effect of clearance is also evident.

  7. The effect of manufacturing tolerances on the load carrying capacity of large diameter bearings

    Indian Academy of Sciences (India)

    Starvin M S; Manisekar K

    2015-09-01

    This paper deals with simplified 3D finite element (FE) analysis on the effect of manufacturing tolerances on the load carrying capacity of large diameter bearings based on Hertz theory. The nonlinear connector elements are used to model the rolling elements. This model enables us to evaluate the contact load on the rolling elements with relatively reduced calculation time. FE study has been carried out by allocating tolerance on balls and raceways using Monte Carlo simulation technique. The variation in dimension on balls is taken as per IS 2898-1976. A coding has been developed and employed for Monte Carlo simulation. Using the results of Monte Carlo simulation, tolerance has been assigned to the elements of large diameter bearing. From the results of finite element analysis, it is identified that analysis of large diameter bearing with tolerance on ball and raceway will lead to safe design.

  8. Disposition of plutonium with HTGRs using Pu burner balls and Th breeder balls

    International Nuclear Information System (INIS)

    A concept of reactor system was developed with which weapons-grade Plutonium could be made perfectly worthless in use for weapons. It is a pebble bed type HTGR using Pu burner ball fuels and Th breeder ball fuels. The residual amounts of 239Pu in spent Pu balls become less than 1% of the initial loading. The power coefficient was made negative by reducing the parasitic neutron absorption reaction rate of 135Xe. (author)

  9. Staging quantum cryptography with chocolate balls

    OpenAIRE

    Svozil, Karl

    2005-01-01

    Moderated by a director, laymen and students are encouraged to assume the role of quanta and enact a quantum cryptographic protocol. The performance is based on a generalized urn model capable of reproducing complementarity even for classical chocolate balls.

  10. Staging quantum cryptography with chocolate balls

    CERN Document Server

    Svozil, K

    2006-01-01

    Moderated by a director, laymen and students are encouraged to assume the role of quanta and enact a quantum cryptographic protocol. The performance is based on a generalized urn model capable of reproducing complementarity even for classical chocolate balls.

  11. On the formation of ball lightning

    International Nuclear Information System (INIS)

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which uner certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma. (author)

  12. Development of high sealing-force, low switching torque ball valves; Entwicklung von Kugelhaehnen mit hoher Dichtkraft und niedrigem Schaltmoment

    Energy Technology Data Exchange (ETDEWEB)

    Bruchhold, I. [rapidea - Lizenzen und Beratung, Berlin (Germany); Grote, K.H. [Magdeburg Univ. (Germany). Inst. fuer Maschinenkonstruktion; California Inst. of Technology, Pasadena, CA (United States). Mechanical Engineering

    2003-09-01

    Ball valves offer significant advantages over other valve types: Their unobstructed passage permits 'pigging', and their compact types are of low weight. The valve plugs of smaller NDs can be supported in floating bearings, guaranteeing extremely high sealing forces, but resulting in relatively high switching torques. Large ND plugs require double bearing systems in order to reduce this. Unfortunately, this principle also results in only relatively low sealing forces. The so-called 'temporary bearing system' has been developed in order to combine the benefits of the two variants, and compensate for their disadvantages: The plug is carried by floating bearings only in the closed position; during the switching process itself, the plug is supported by means of a hydraulically activated bearing system. Switching torques can be reduced by up to 60% compared to existing technology with a comparably high sealing force using the temporary bearing system. For this reason, only significantly smaller and more rationally priced actuator systems are needed. Ball valves with temporary-bearing plugs can be advantageous and reduce costs in pipelines, in plant engineering, supply systems, in the chemicals industry and in pipelines. (orig.)

  13. Aerodynamic drag of modern soccer balls

    OpenAIRE

    Asai, Takeshi; Seo, Kazuya

    2013-01-01

    Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through...

  14. Gravitational waves from Q-ball formation

    International Nuclear Information System (INIS)

    We study the detectability of the gravitational waves (GWs) from the Q-ball formation associated with the Affleck-Dine (AD) mechanism, taking into account both the dilution effects due to Q-ball domination and to finite temperature. The AD mechanism predicts the formation of nontopological solitons, Q-balls, from which GWs are generated. Q-balls with large conserved charge Q can produce a large amount of GWs. On the other hand, the decay rate of such Q-balls is so small that they may dominate the energy density of the Universe, which implies that GWs are significantly diluted and that their frequencies are redshifted during the Q-ball dominated era. Thus, the detectability of the GWs associated with the formation of Q-balls is determined by these two competing effects. We find that there is a finite but small parameter region where such GWs may be detected by future detectors such as DECIGO or BBO, only in the case when the thermal logarithmic potential dominates the potential of the AD field. Otherwise GWs from Q-balls would not be detectable even by these futuristic detectors: ΩGW0-21. Unfortunately, for such parameter region the present baryon asymmetry of the Universe can hardly be explained unless one fine-tunes A-terms in the potential. However the detection of such a GW background may give us an information about the early Universe, for example, it may suggest that the flat directions with B-L=0 are favored.

  15. Random Signal Analysis for Bearing Vibration%轴承振动的随机讯号分析

    Institute of Scientific and Technical Information of China (English)

    王桂金

    2000-01-01

    It was assumed that the vibration generated by rotating a near perfect ball bearing will produce random signals if the bearing does not have significant defects on the rings and/or on the balls,and if grease and surfaces are free of foreign particles.If fatigue damage of the bearing develops at a slow rate,the stationary vibration signal,i.e.,an ergodic process,would result.The chi-square test was then proposed to check the normality of the vibration signal distribution.

  16. Comparison of FEA with condition monitoring for real-time damage detection of bearing using infrared thermography techniques

    International Nuclear Information System (INIS)

    Since real-time monitoring systems, such as early fault detection, have been very important, an infrared thermography technique was proposed as a new diagnosis method. This study focused on damage detection and temperature characteristic analysis of ball bearings using the non-destructive, infrared thermography method. In this paper, for the reliability assessment, infrared experimental data were compared with finite element analysis (FEA) results from ANSYS. In this investigation, the temperature characteristics of ball bearing were analyzed under various loading conditions. Finally, it was confirmed that the infrared thermography technique was useful for the real-time detection of damage to bearings

  17. Heated-Pressure-Ball Monopropellant Rocket Engine

    Science.gov (United States)

    Greene, William D.

    2005-01-01

    A recent technology disclosure presents a concept for a monopropellant thermal spacecraft thruster that would feature both the simplicity of a typical prior pressure-fed propellant supply system and the smaller mass and relative compactness of a typical prior pump-fed system. The source of heat for this thruster would likely be a nuclear- fission reactor. The propellant would be a cryogenic fluid (a liquefied low-molecular-weight gas) stored in a tank at a low pressure. The propellant would flow from the tank, through a feedline, into three thick-walled spherical tanks, denoted pressure balls, that would be thermally connected to the reactor. Valves upstream and downstream of the pressure balls would be operated in a three-phase cycle in which propellant would flow into one pressure ball while the fluid underwent pressurization through heating in another ball and pressurized propellant was discharged from the remaining ball into the reactor. After flowing through the reactor, wherein it would be further heated, the propellant would be discharged through an exhaust nozzle to generate thrust. A fraction of the pressurized gas from the pressure balls would be diverted to maintain the desired pressure in the tank.

  18. Experimental Investigation of Friction Effect on Liner Model Rolling Bearings for Large Diameter Thrust Bearing Design

    Directory of Open Access Journals (Sweden)

    S. Babu

    2012-12-01

    Full Text Available Studying friction coefficient has significant importance, especially when dealing with high load and temperature applications that have frequent starting and stopping points. Towards that, two sets of angular contact Linear Model Mockup Bearings (LMMB were designed and fabricated. This linear model assembly was made up of high precision, grounded raceways (AISI 4140 and commercially purchased balls (AISI 52100. The experimental studies were carried out by placing different number of balls between the raceways under different loads at dry lubricating condition. The static friction coefficients were measured using two different experiments: viz gravitation-based experiment and direct linear force measurement experiment. And Digital Image Correlation (DIC technique was used to find the stiffness of LMMB set.

  19. Secret of a ball lightning

    OpenAIRE

    E.V. Savich

    2013-01-01

    Шаровая молния – явление природы, происходящее при ударе линейной молнии с ее воздействием тепловой и магнитной энергии, возникающей вокруг канала линейной молнии и в результате образующей из окружающего воздуха облако пара, переходящего под воздействием магнитного поля сегнетоэлектрическое состояние. A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming...

  20. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  1. Rolling Bearing Life Prediction, Theory, and Application

    Science.gov (United States)

    Zaretsky, Erwin V.

    2013-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg- Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application.

  2. Effect of a ball skill intervention on children's ball skills and cognitive functions

    NARCIS (Netherlands)

    Westendorp-Haverdings, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    2014-01-01

    Purpose: This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning

  3. Aerodynamic drag of modern soccer balls.

    Science.gov (United States)

    Asai, Takeshi; Seo, Kazuya

    2013-12-01

    Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10(5) (drag coefficient, C d  ≈ 0.12), ~2.8 × 10(5) (C d  ≈ 0.13), ~3.3 × 10(5) (C d  ≈ 0.13), and ~2.4 × 10(5) (C d  ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces. PMID:23705104

  4. EFFECTS OF STABILIZATION EXERCISE USING A BALL ON MUTIFIDUS CROSS-SECTIONAL AREA IN PATIENTS WITH CHRONIC LOW BACK PAIN

    Directory of Open Access Journals (Sweden)

    SinHo Chung

    2013-09-01

    Full Text Available The purpose of this study was to compare the effects of lumbar stabilization exercises using balls to the effects of general lumbar stabilization exercises with respect to changes in the cross section of the multifidus (MF, weight bearing, pain, and functional disorders in patients with non-specific chronic low back pain. Twelve patients participated in either a 8 week (3 days per week stabilization exercise program using balls and control group (n = 12. The computer tomography (CT was used to analyze MF cross-sectional areas (CSA and Tetrax balancing scale was used to analyze left and right weight bearing differences. Both groups had significant changes in the CSA of the MF by segment after training (p < 0.05 and the experimental group showed greater increases at the L4 (F = 9.854, p = 0.005 and L5 (F = 39. 266, p = 0.000. Both groups showed significant decreases in weight bearing, from 9.25% to 5.83% in the experimental group and from 9.33% to 4.25% in the control group (p < 0.05, but did not differ significantly between the two groups. These results suggests that stabilization exercises using ball can increases in the CSA of the MF segments, improvement in weight bearing, pain relief, and recovery from functional disorders, and the increases in the CSA of the MF of the L4 and L5 segments for patients with low back pain

  5. Maintenance Free Bearings

    OpenAIRE

    S. M. Muzakkir & Harish Hirani

    2015-01-01

    In the present research work the need of a Maintenance Free Bearings (MFB) is established. The paper presents preliminary friction calculations to highlight the ways to achieve maintenance free bearings. The existing technologies of well established maintenance free bearings are described. The hybridization of bearing technologies to achieve low cost maintenance free bearings has been exemplified. Finally a combination of passive magnetic repulsion and hydrodynamics ha...

  6. Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

    Science.gov (United States)

    Carboch, Jan; Süss, Vladimir; Kocib, Tomas

    2014-01-01

    Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server). Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing. Key points Players have shorter initial move time when they are facing the ball machine. Using the ball machine results in different swing timing and movement coordination. The use of the ball machine should be limited. PMID:24790483

  7. Flight trajectory of a rotating golf ball with grooves

    Science.gov (United States)

    Baek, Moonheum; Kim, Jooha; Choi, Haecheon

    2014-11-01

    Dimples are known to reduce drag on a sphere by the amount of 50% as compared to a smooth surface. Despite the advantage of reducing drag, dimples deteriorate the putting accuracy owing to their sharp edges. To minimize this putting error but maintain the same flight distance, we have devised a grooved golf ball (called G ball hereafter) for several years. In this study, we modify the shape and pattern of grooves, and investigate the flow characteristics of the G ball by performing wind-tunnel experiments at the Reynolds numbers of 0 . 5 ×105 - 2 . 5 ×105 and the spin ratios (ratio of surface velocity to the free-stream velocity) of 0 - 0.6 that include the real golf-ball velocity and rotational speed. We measure the drag and lift forces on the rotating G ball and compare them with those of a smooth ball and two well-known dimpled balls. The lift-to-drag ratio of the G ball is much higher than that of a smooth ball and is in between those of the two dimpled balls. The trajectories of flying golf balls are computed. The flight distance of G ball is almost the same as that of one dimpled ball but slightly shorter than that of the other dimpled ball. The fluid-dynamic aspects of these differences will be discussed at the talk. Supported by 2011-0028032, 2014M3C1B1033980.

  8. Dark matter balls help supernovae to explode

    Science.gov (United States)

    Froggatt, C. D.; Nielsen, H. B.

    2015-10-01

    As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova, the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat — of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating due to the dark matter balls would at first stop the collapse of the supernova progenitor. This opens up the possibility of there being two collapses giving two neutrino outbursts, as apparently seen in the supernova SN1987A — one in Mont Blanc and one 4 h 43 min later in both IMB and Kamiokande.

  9. On the Ball-Constrained Weighted Maximin Dispersion Problem

    OpenAIRE

    Wang, Shu; Xia, Yong

    2016-01-01

    The ball-constrained weighted maximin dispersion problem $(\\rm P_{ball})$ is to find a point in an $n$-dimensional Euclidean ball such that the minimum of the weighted Euclidean distance from given $m$ points is maximized. We propose a new second-order cone programming relaxation for $(\\rm P_{ball})$. Under the condition $m\\le n$, $(\\rm P_{ball})$ is polynomial-time solvable since the new relaxation is shown to be tight. In general, we prove that $({\\rm P_{ball}})$ is NP-hard. Then, we propos...

  10. Algorithm on robot soccer pass and shoot a ball

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Introduces of robot soccer's competition software of Harbin Institute of Technology(HIT), the con cept of running range and the method of calculating the running range for both the opponent and our teammates according to the distances Between the ball and robot soccers, and therefore the method of calculating the angle that the robot passes or shoots the ball according to the running ranges of both sides. And gives the examples of passing the ball when the ball's position is in the backcourt and shooting the ball when the ball's position is in the frontcourt.

  11. Flaglets: Exact Wavelets on the Ball

    CERN Document Server

    Leistedt, Boris

    2013-01-01

    We summarise the construction of exact axisymmetric scale-discretised wavelets on the sphere and on the ball. The wavelet transform on the ball relies on a novel 3D harmonic transform called the Fourier-Laguerre transform which combines the spherical harmonic transform with damped Laguerre polynomials on the radial half-line. The resulting wavelets, called flaglets, extract scale-dependent, spatially localised features in three-dimensions while treating the tangential and radial structures separately. Both the Fourier-Laguerre and the flaglet transforms are theoretically exact thanks to a novel sampling theorem on the ball. Our implementation of these methods is publicly available and achieves floating-point accuracy when applied to band-limited signals.

  12. The bouncing ball through a geometrical series

    Science.gov (United States)

    Flores, Sergio; Alfaro, Luis L.; Chavez, Juan E.; Bastarrachea, Aztlan; Hurtado, Jazmin

    2008-10-01

    The mathematical representation of the physical situation related to a bouncing ball on the floor is an important understanding difficulty for most of the students during the introductory mechanics and mathematics courses. The research group named Physics and mathematics in context from the University of Ciudad Juarez is concerned about the versatility in the change from a mathematical representation to the own physical context of any problem under a traditional instruction. In this case, the main idea is the association of the physical properties of the bouncing ball situation to the nearest mathematical model based on a geometrical series. The proposal of the cognitive development is based on a geometrical series that shows the time the ball takes to stop. In addition, we show the behavior of the ratio of the consecutive heights during the motion.

  13. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-01-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics. PMID:27328835

  14. Electrostatic charge bounds for ball lightning models

    International Nuclear Information System (INIS)

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings

  15. Fire ball in LIB-ICF reactor

    International Nuclear Information System (INIS)

    In the design of LIB-ICF Reactor, it is the most impotant probrem to choose the cavity gas. In order to transport the light ion beam without a large collisional loss, the cavity gas density must be low enough. On the other hand, the fusion energy is transported by neutrons, X-ray and pellet deblis. The energy of X-ray and pellet debris is absorbed in the cavity gas and then fire ball is generated. The propagation of fire ball and the load to the cavity wall are varied with the density, temperature, components and mixture-rate of the gas. In the case of liquid-wall reactor, it should be mixed with the cavity gas. In this study, the behavior of fire ball is investigated by using the computer code FIRE, so that the components of the cavity gas and other parameters are determined. (author)

  16. From Schwinger Balls to Black Holes

    CERN Document Server

    Allahbakhshi, Davood

    2016-01-01

    We have shown intriguing similarities between Schwinger balls and black holes. By considering black hole as a gravitational Schwinger ball, we have derived the Bekenstein-Hawking entropy and the first law of black hole thermodynamics as a direct result of the inverse area dependence of the gravitational force. It is also shown that the Planck length is nothing but the gravitational Schwinger length. The relation between the mass and the radius of the black hole is derived by considering the black hole as a Schwinger ball of gravitons. We show how the evolution of the entanglement entropy of the black hole, as Page introduced many years ago, can be obtained by including gravitons in the black hole's evaporation process and using a deformed EPR mechanism. Also this deformed EPR mechanism can solve the information paradox. We show how naive simultaneous usage of Page's argument and equivalence principle leads to firewall problem.

  17. Drag Crisis of Gyro-Balls

    Science.gov (United States)

    Yokoyama, Yoshiyuki; Miyazaki, Takeshi; Himeno, Ryutaro

    2007-11-01

    Using a high-speed video camera, we measured the trajectory and the rotation of a hard baseball thrown by a pitching machine which can launch Gyro-Balls (rifle spinning balls). We determined the drag- and lift- coefficients by analyzing the video images. The measurements were performed in the range of 0.6x10^5ball with SP=0.12,0.23 and 0.35, decreases gradually with Re. However, the drag coefficient of a 2-seam gyro-ball with SP=0.12 decreases in two steps, i.e. in the ranges 0.8x10^5Ball with SP=0.23,0.35 are almost constant below Re=1.6x10^5 and Re=1.3x10^5, respectively. Their minima are attained at Re=1.8x10^5 and Re=1.6x10^5, respectively. These findings confirm the occurrence of the drag crisis for Gyro-Balls. The different Re-dependencies are due to the different seam patterns.

  18. Q-balls in Underground Experiments

    CERN Document Server

    Ouchrif, M

    2000-01-01

    In this paper we present some features of Q-balls and we discuss theirinteractions with matter, and their energy losses in the Earth, for a largerange of velocities. These calculations are used to compute the fractionalgeometrical acceptance of the MACRO detector. Furthermore a systematic analysisof the energy losses of Q-balls in three types of detectors is investigated.More specifically we have computed the light yield in liquid scintillators, theionization in streamer tubes and the Restricted Energy Loss in the CR39 nucleartrack detectors.

  19. Soccer ball lift coefficients via trajectory analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2010-07-15

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.

  20. Reasonable Ball Size of Ball Mill for Preparing Coal Water Fuel and Forecasting Productive Capacity

    Institute of Scientific and Technical Information of China (English)

    张荣曾; 刘炯天; 徐志强; 郑明

    2002-01-01

    By using the matrix theory, a 5-parameter grinding mathema tical model is established. Based on the properties of feed coal and requirement s for size distribution of final product, the model gives the required grinding probability for various particles and corresponding ball size distribution. By u sing this model, 3 different sizes of ball mill are designed and put into commer cial use for coal water fuel. The forecasted ball mill capacity, the particle si zes and particle size distribution as well as the coal water fuel quality parame ters are all in line with industrial operation results, which have proved the su itability of the model.

  1. History of Space Shuttle Main Engine Turbopump Bearing Testing at the Marshall Space Flight Center

    Science.gov (United States)

    Gibson, Howard; Thom, Robert; Moore, Chip; Haluck, Dave

    2010-01-01

    The Space Shuttle is propelled into orbit by two solid rocket motors and three liquid fed main engines. After the solid motors fall away, the shuttle engines continue to run for a total time of 8 minutes. These engines are fed propellants by low and high pressure turbopumps. A critical part of the turbopump is the main shaft that supports the drive turbine and the pump inducer and impeller. Rolling element bearings hold the shaft in place during rotation. If the bearings were to fail, the shaft would move, allowing components to rub in a liquid oxygen or hydrogen environment, which could have catastrophic results. These bearings are required to spin at very high speeds, support radial and axial loads, and have high wear resistance without the benefit of a conventional means of lubrication. The Rocketdyne built Shuttle turbopumps demonstrated their capability to perform during launches; however, the seven hour life requirement was not being met. One of the limiting factors was the bearings. In the late 1970's, an engineering team was formed at the Marshall Space Flight Center (MSFC), to develop a test rig and plan for testing the Shuttle s main engine high pressure oxygen turbopump (HPOTP) bearings. The goals of the program were to better understand the operation of bearings in a cryogenic environment and to further develop and refine existing computer models used to predict the operational limits of these bearings. In 1982, testing began in a rig named the Bearing and Seal Material Tester or BSMT as it was commonly called. The first testing investigated the thermal margin and thermal runaway limits of the HPOTP bearings. The test rig was later used to explore potential bearing improvements in the area of increased race curvatures, new cage materials for better lubrication, new wear resistant rolling element materials, and other ideas to improve wear life. The most notable improvements during this tester s time was the incorporation of silicon nitride balls and

  2. Detecting supersymmetric Q-balls with neutron stars

    OpenAIRE

    Madsen, Jes

    1998-01-01

    Supersymmetric Q-balls trapped in neutron stars or white dwarfs may cause the stars to explode. Trapping of Q-balls in neutron stars is shown to be less likely, but trapping in neutron star progenitors more likely than hitherto assumed, making neutron stars very sensitive Q-ball "detectors". White dwarfs only trap potentially dangerous Q-balls in a narrow parameter range.

  3. Holomorphic Spaces in the Unit Ball of

    Directory of Open Access Journals (Sweden)

    Augusto Guadalupe Miss Paredes

    2013-01-01

    Full Text Available We introduce the and vector spaces of holomorphic functions defined in the unit ball of , generalizing previous work like Ouyang et al. (1998, Stroethoff (1989, and Choa et al. (1992. Likewise, we characterize those spaces in terms of harmonic majorants as a generalization of Arellano et al. (2000.

  4. A plasma ball in the Microcosm museum

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Plasma balls, like the one shown here, are displayed in the Microcosm exhibition where families can visit to learn more about the experiments carried out in a research institute like CERN. Hands-on activities allow visitors to get a step closer to the research activities carried out at CERN.

  5. Visitor playing with a plasma ball

    CERN Multimedia

    1997-01-01

    Plasma balls, like the one shown here, are displayed in the Microcosm exhibition where families can visit to learn more about the experiments carried out in a research institute like CERN. Hands-on activities allow visitors to get a step closer to the research activities carried out at CERN.

  6. 4 π physics with the plastic ball

    International Nuclear Information System (INIS)

    4 π data taken with the Plastic Ball show that cluster production in relativistic nuclear collisions depends on both the size of the participant volume and the finite size of the cluster. The measurement of the degree of thermalization and the search for collective flow will permit the study of the applicability of macroscopic concepts such as temperature and density

  7. Dark Matter Balls Help Supernovae to Explode

    CERN Document Server

    Froggatt, Colin D

    2015-01-01

    As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat - of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating d...

  8. Selection of Parameters in Ball-Spinning

    Institute of Scientific and Technical Information of China (English)

    Maosheng LI; Yongnian YAN; Shihong ZHANG; Dachang KANG

    2004-01-01

    Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is still unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the working angle, the axial feeding rate, and the acceptable working course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the ball diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.

  9. Crystal Ball results on tau decays

    International Nuclear Information System (INIS)

    This report reviews measurements and upper limit determinations for a number of exclusive 1-prong tau decay modes using the Crystal Ball detector. These results are important input to the apparent discrepancy between the topological and sum-of-exclusive branching fractions in 1-prong tau decays

  10. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  11. The Ball Aptitude Battery (Test Review).

    Science.gov (United States)

    Hall, Alfred E.

    1985-01-01

    The 12 subtests of the Ball Aptitude Battery (BAB) listed in the administration manual were described. The reviewer believes this aptitude battery, designed for use with high school students and adults in job selection and placement, needs major improvements. It is suggested that the BAB be used solely for research purposes. (DWH)

  12. The dynamic behavior of squash balls

    Science.gov (United States)

    Lewis, Gareth J.; Arnold, J. Cris; Griffiths, Iwan W.

    2011-03-01

    The behavior of a squash ball constitutes an excellent case study of the dynamic behavior of rubbery materials. It is shown that the complex viscoelastic behavior of rubber can be investigated using simple drop bounce tests and compression tests. The drop tests show that the coefficient of restitution increases as the ball temperature increases. The compression tests show that as the speed of compression increases or as the ball temperature decreases, the compressive force and the energy loss both increase. These effects are due to the viscoelastic nature of the rubber and are an excellent example of the time-temperature equivalence of polymers. Compression tests were performed on balls with small holes at the base to separate the effects of the internal air pressure from the material deformation. It was found that the internal air pressure contributed about one-third to the compressive force, but contributed little to energy loss. This behavior shows that the rubber material dominates the rebound behavior and that the normal warming up process at the start of a squash game is important to raise the temperature of the rubber rather than to increase the internal air pressure.

  13. Neutrino Balls and Gamma-Ray Bursts

    CERN Document Server

    Holdom, B

    1994-01-01

    We propose a mechanism by which the neutrino emission from a supernova-type explosion can be converted into a gamma-ray burst of total energy $\\sim 10^{50}$ ergs. This occurs naturally if the explosion is situated inside a ball of trapped neutrinos, which in turn may lie at a galactic core. There are possible unique signatures of this scenario.

  14. 4. pi. physics with the plastic ball

    Energy Technology Data Exchange (ETDEWEB)

    Gutbrod, H.H.; Loehner, H.; Poskanzer, A.M.; Renner, T.; Riedesel, H.; Ritter, H.G.; Warwick, A.; Weik, F.; Wieman, H.

    1982-10-01

    4 ..pi.. data taken with the Plastic Ball show that cluster production in relativistic nuclear collisions depends on both the size of the participant volume and the finite size of the cluster. The measurement of the degree of thermalization and the search for collective flow will permit the study of the applicability of macroscopic concepts such as temperature and density.

  15. Soccer Ball Production for Nike in Pakistan

    NARCIS (Netherlands)

    K.A. Siegmann (Karin Astrid)

    2008-01-01

    textabstractThis paper looks at how Nike’s soccer ball suppliers (previous and current) in Sialkot (Pakistan) fare in relation to the company’s code of ethics. While minimum required working conditions are implemented, the criteria for social and environmental compliance are not met with. The multin

  16. Spherical polytropic balls cannot mimic black holes

    Science.gov (United States)

    Saida, Hiromi; Fujisawa, Atsuhito; Yoo, Chul-Moon; Nambu, Yasusada

    2016-04-01

    The so-called black hole shadow is a dark region which is expected to appear in a fine image of optical observation of black holes. It is essentially an absorption cross section of the black hole, and the boundary of shadow is determined by unstable circular orbits of photons (UCOP). If there exists a compact object possessing UCOP but no black hole horizon, it can provide us with the same shadow image as black holes, and detection of a shadow image cannot be direct evidence of black hole existence. This paper examines whether or not such compact objects can exist under some suitable conditions. We investigate thoroughly the static spherical polytropic ball of perfect fluid with single polytrope index, and then investigate a representative example of a piecewise polytropic ball. Our result is that the spherical polytropic ball which we have investigated cannot possess UCOP, if the speed of sound at the center is subluminal (slower than light). This means that, if the polytrope treated in this paper is a good model of stellar matter in compact objects, the detection of a shadow image can be regarded as good evidence of black hole existence. As a by-product, we have found the upper bound of the mass-to-radius ratio of a polytropic ball with single index, M_{ast }/R_{ast } < 0.281, under the condition of subluminal sound speed.

  17. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...

  18. Q-balls in the Wick-Cutkosky model

    CERN Document Server

    Nugaev, E Ya

    2016-01-01

    In the present paper Q-ball solutions in the Wick-Cutkosky model are examined in detail. A remarkable feature of the Wick-Cutkosky model is that it admits analytical treatment for the most part of the analysis of Q-balls. An attempt is made to describe Q-balls as bound states of scalar particles.

  19. Interrelation between ball lightning and optically induced forces

    International Nuclear Information System (INIS)

    Optically induced forces are considered as a key factor for explaining the phenomenon of ball lightning. They can provide not only the existence of ball lightning in the form of self-confined intense white light circulating in a spherical shell of air strongly compressed by the light but also the anomalous motion of ball lightning in the terrestrial atmosphere. (paper)

  20. Temperature and Coefficient of Restitution of a Table Tennis Ball

    Directory of Open Access Journals (Sweden)

    Yoonyoung Chang

    2016-01-01

    Full Text Available The coefficient of restitution (COR of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  1. Measuring the Rebound Resilience of a Bouncing Ball

    Science.gov (United States)

    Wadhwa, Ajay

    2012-01-01

    Some balls which are made of high-quality rubber (an elastomeric) material, such as tennis or squash balls, could be used for the determination of an important property of such materials called resilience. Since a bouncing ball involves a single impact we call this property "rebound resilience" and express it as the ratio of the rebound height to…

  2. Energy density calculations for ball-lightning-like luminous silicon balls

    International Nuclear Information System (INIS)

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m-3, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model. (methodological notes)

  3. Disposition of weapon-grade plutonium with pebble bed type HTGRs using Pu burner balls and Th breeder balls

    International Nuclear Information System (INIS)

    A concept of reactor system was developed with which weapons-grade plutonium could be made perfectly worthless in use for weapons. It is a pebble bed type HTGR using Pu burner ball fuels and Th breeder ball fuels. The residual amounts of 239Pu in spent Pu balls become less than 1% of the initial loading. Furthermore, a method was found that the power coefficient could be made negative by heavy Pu loading in the Pu burner ball fuels

  4. Steel balls forming by cross rolling with upsetting

    Directory of Open Access Journals (Sweden)

    Z. Pater

    2013-01-01

    Full Text Available The paper describes a process of forming four balls with a diameter of 22 mm by means of cross rolling with upsetting. The paper also presents the tool used to form semi-finished balls. Owing to the application of the finite element method (FEM, the course of the rolling process as well as temperature and strain distributions in the obtained balls could be presented. The rolling tests conducted in laboratory conditions at the Lublin University of Technology have proved that the balls produced with the developed rolling method meet the demands for grinding media used in ball mills.

  5. Lawn tennis balls, Rolling friction experiment and Trouton viscosity

    CERN Document Server

    Singh, Ankit; Kulkarni, Kaustubh; Budhraja, Abhishek; Tej, K R Sai; Sankarlingam, Satish; Biswas, Anindya Kumar

    2008-01-01

    Three lawn tennis balls were arbitrarily taken. One ball was new, one was moderately old and another was old. We have fabricated a conveyor belt set-up and measured rolling friction coefficients, $\\mu_{r}$, of the three balls as a function of their angular velocities, $\\omega$. For the new ball, quadratic fit is perfect. For the moderately old ball, linear fit is accurate. In all the three cases, from linear fits, we obtain $k_{rol}$, where, $\\mu_{r}= k_{rol} \\omega + intercept$. We deduce $k_{rol}$ theoretically also, assuming Trouton ratio as three. The experimental results and theoretical estimates are of the same order of magnitude.

  6. Vision-based surface defect inspection of metal balls

    International Nuclear Information System (INIS)

    A machine vision system developed for inspecting metal ball surface defects is presented. The proposed system is capable of inspecting the entire surface of a ball by capturing multiple gray-scale images with two progressive CCD cameras as the ball rolls on an inclined rail. The specular reflectance of the metal surface is lessened by installing a shade around the ball. Defects are detected by simply comparing each captured image with its corresponding reference image. The system built for the experiment could sort two chrome balls per second with a spatial resolution better than 0.1 mm. (technical design note)

  7. Space Shuttle Body Flap Actuator Bearing Testing for NASA Return to Flight

    Science.gov (United States)

    Jet, Timothy R.; Predmore, Roamer E.; Dube, Michael; Jones, William R., Jr.

    2006-01-01

    The Space Shuttle body flap (BF) is located beneath the main engine nozzles and is required for proper aerodynamic control during orbital descent. The body flap is controlled by four actuators connected by a common shaft and driven by the hydraulic power drive unit. Inspection of the actuators during refurbishment revealed three shaft bearings with unexpected damage. One was coated with black oxide on the balls and race wear surfaces, a second contained a relatively deep wear scar, and the third with scratches and an aluminum particle in the wear track. A shaft bearing life test program was initiated to measure the wear life and explain the 5.08-micrometer wear scar. A tribological analysis was conducted to demonstrate that the black oxide coated wear surfaces did not damage the bearing, interfere with the lubrication, or cause severe bearing wear. Pre-damaged (equivalent of 30 missions), commercial equivalent bearings and previously flown shaft bearings were tested at axial loads, speeds, and temperatures seen during flight operations. These bearing were successfully life tested at 60 C for 24 hours or 90 flights. With a safety factor of 4X, the bearings were qualified for 22 flights when only a maximum of 12 flights are expected. Additional testing at 23 C was performed to determine the lubricant life and to further understand the mechanism that caused the blackened balls. Test results indicating bearing life was shortened at a lower temperature surprised the investigators. Start\\Stop bearing testing that closely simulates mission profile was conducted at 23 C. Results of this testing showed lubricant life of 12 flights including a safety factor of four. Additional testing with bearings that have the equivalent of 30 missions of damage is being tested at 23 C. These tests are being performed over the Shuttle load profile to demonstrate the residual bearing life in the actuators exceeds 12 missions. Testing showed that the end of the shaft bearing life was

  8. Sitting on stability balls: biomechanics evaluation in a workplace setting.

    Science.gov (United States)

    Schult, Tamara M; Awosika, Ebi R; Schmunk, Sandra K; Hodgson, Michael J; Heymach, Bria L; Parker, Celestine Dent

    2013-01-01

    Use of a stability ball alone and stability ball chair were evaluated in the Veterans Health Administration as possible alternatives to incorporate with regular office chair use. The evaluation of stability ball use was conducted under the auspices of a work site health promotion program as a cross-over trial with participants rotating through use of the stability ball, stability ball chair, and regular office chair on a monthly basis for a total duration of 3 months. Rotations on regular office chairs served as the control. Three medical facilities participated. A total of 193 employees completed a baseline questionnaire; 159 completed at least one post-rotation questionnaire. Self-reported measures included perceived posture when sitting, perceptions of overall balance, energy levels, job performance, safety, and pain. Use was associated with improvements in perceived posture (p < 0.0001) and energy levels (p = 0.007) for stability ball users compared with the office chair control, and improvements in perceived posture (p < 0.0001) and overall balance (p = 0.05) for stability ball chair users compared with the control. Use of stability balls at work decreases the likelihood of reporting pain from regular office chair use from approximately 45% to 21%. Alternatively, a high number of participants reported pain with use of the stability ball alone and stability ball chair, 42% and 45%, respectively. The perceived risks and benefits of stability ball use should be weighed when incorporating use. PMID:23252582

  9. Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

    Directory of Open Access Journals (Sweden)

    Jan Carboch, Vladimir Süss, Tomas Kocib

    2014-06-01

    Full Text Available Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server. Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing.

  10. Isoguanine octamer: From bowl to ball

    Science.gov (United States)

    Gu, Jiande; Wang, Jing; Leszczynski, Jerzy

    2007-09-01

    Isoguanine (2-oxo-6-amino-guanine, isoG) can form the higher-order self-pairing ionophore structures by regulating the concentration of metal ions. The metal ion coordinated isoG-tetrads adopt bowl-like shape with the metal ion located at the bottom of the bowl. The present study of the formation of the H-bonded octamers ((isoG 4-M +) 2; M + = Na +, K +) illustrates that the bowl-shaped isoG 4-M + complexes are able to form the extraordinary ball-shaped octamers (isoG 4-M +) 2 H-bonded through the H(N6) and N7 sites. A moderate energy barrier predicted for the process of separating the ball-shaped octamer into two bowl-shaped tetrads and the unique structural features of the octamer suggests a possibility towards construction of the self-assembled isoG nanostructures.

  11. The effect of solid film lubricants on the stability of rolling element bearings

    Science.gov (United States)

    Kannel, J. W.; Merriman, T. L.

    1987-01-01

    A technique has been developed for modeling solid films in rolling element bearings. For a given bearing geometry an effective viscosity can be calculated for a solid film as a function of the film shear modulus and ball-race friction coefficient. The calculated effective viscosity can subsequently be used as an input to a numerical model of cage motion and stability. Results from a sample calculation of effective viscosity and prediction of cage stability for a turbopump bearing are presented for films of molybdenum disulfide (MoS2) and polytetrafluoroethylene ()PTFE).

  12. Soccer Ball Production for Nike in Pakistan

    OpenAIRE

    Siegmann, Karin Astrid

    2008-01-01

    textabstractThis paper looks at how Nike’s soccer ball suppliers (previous and current) in Sialkot (Pakistan) fare in relation to the company’s code of ethics. While minimum required working conditions are implemented, the criteria for social and environmental compliance are not met with. The multinational’s decision to withdraw orders from the previous supplier ostensibly due to allegations of child labour and unauthorised subcontracting hit large sections of the workforce, especially rural,...

  13. Tuned ball absorber acting in one direction

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš; Urushadze, Shota

    US : SEM, 2004 - (Wicks, A.), s. 150-158 ISBN 0-912053-86-0. ISSN 1046-6770. [IMAC-XXII Conference on Structural Dynamic s. Dearborn (US), 26.01.2004-29.01.2004] R&D Projects: GA AV ČR KJB2071303 Institutional research plan: CEZ:AV0Z2071913 Keywords : ball absorber * acceleration * frequency Subject RIV: JM - Building Engineering

  14. Independence, low balling and learning effects

    OpenAIRE

    Simons, Dirk

    2007-01-01

    Independent auditors serve as gatekeepers of public securities markets, but ongoing competition among audit firms could harm auditors’ independence. For instance, a Green Paper of the European Union finds that especially audits of large and prestigious clients are hard-fought in terms of price competition. Major concerns are related to a pricing behavior called low balling. Here, the auditor sets the first period’s fee below the audit costs -incurring a loss for the initial audit- in order to...

  15. Ball-thrower's fracture of the humerus

    International Nuclear Information System (INIS)

    A relatively rare case of ball-thrower's fracture of the humerus is presented. Severe muscular action is an uncommon cause of humeral fractures but has been well documented in the orthopedic literature. To our knowledge, this fracture has not been described in the radiology literature, and awareness of this entity could preclude further unnecessary workup. The mechanism of injury and its typical radiographic appearance is described. (orig.)

  16. Gravitational effects on critical Q-balls

    Science.gov (United States)

    Metaxas, D.

    2007-04-01

    In a cosmological phase transition in theories that admit Q-balls there is a value of the soliton charge above which the soliton becomes unstable and expands, converting space to the true vacuum, much like a critical bubble in the case of ordinary tunneling. Here I consider the effects of gravity on these solitons and I calculate the lowest gravitational corrections to the critical radius and charge.

  17. Gravitational effects on critical Q-balls

    CERN Document Server

    Metaxas, D

    2004-01-01

    In a first-order phase transition in theories that admit Q-balls there is a value of the soliton charge above which the soliton becomes unstable and expands, converting space to the true vacuum, much like a critical bubble in the case of ordinary tunneling. Here I consider the effects of gravity on these solitons and I calculate the lowest gravitational corrections to the critical radius and charge.

  18. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  19. Ball plasma dynamics for FBX BURNER reactor

    International Nuclear Information System (INIS)

    The authors have been conducting fundamental experiments on the moving plasma balls in the major axis direction. This has a fundamental importance for the quasi-steady fusion reactor scheme FBX BURNER. This configuration is the descendants of Spheromak type nuclear fusion scheme but with long toroidal field coils. The main issues have been focused onto the dynamic stability of the moving plasma balls. The second issue is the collision between two successive plasma balls as shown. This shows a basic result from an optical measurement. The comparison with magnetic measurements shows peculiar but interesting features of the system. The dimension of the plasma injector is 2 m in length as a whole. It is in a coaxial configuration. The external electrode is 150 mm in inner diameter and the inner electrode is 50 mm in diameter. This is attached to a 1 m insulation reservoir with same inner diameter. An axial magnetic field up to 0.1 Tesla is applied on the discharge with a current of up to 10 kA in few ms. The authors show their experimental and numerical simulation results on these problems

  20. Bear Spray Safety Program

    Science.gov (United States)

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  1. Optimal Synchronizability of Bearings

    OpenAIRE

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S.

    2013-01-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)]. We show that, in analogy...

  2. Bearing restoration by grinding

    Science.gov (United States)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  3. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager;

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

  4. Aerodynamics in the classroom and at the ball park

    Science.gov (United States)

    Cross, Rod

    2012-04-01

    Experiments suitable for classroom projects or demonstrations are described concerning the aerodynamics of polystyrene balls. A light ball with sufficient backspin can curve vertically upward through the air, defying gravity and providing a dramatic visual demonstration of the Magnus effect. A ball projected with backspin can also curve downward with a vertical acceleration greater than that due to gravity if the Magnus force is negative. These effects were investigated by filming the flight of balls projected in an approximately horizontal direction so that the lift and drag forces could be easily measured. The balls were also fitted with artificial raised seams and projected with backspin toward a vertical target in order to measure the sideways deflection over a known horizontal distance. It was found that (a) a ball with a seam on one side can deflect either left or right depending on its launch speed and (b) a ball with a baseball seam can also deflect sideways even when there is no sideways component of the drag or lift forces acting on the ball. Depending on the orientations of the seam and the spin axis, a sideways force on a baseball can arise either if there is rough patch on one side of the ball or if there is a smooth patch. A scuff ball with a rough patch on one side is illegal in baseball. The effect of a smooth patch is a surprising new observation.

  5. Diagnosis of Bearing System using Minimum Variance Cepstrum

    International Nuclear Information System (INIS)

    Various bearings are commonly used in rotating machines. The noise and vibration signals that can be obtained from the machines often convey the information of faults and these locations. Monitoring conditions for bearings have received considerable attention for many years, because the majority of problems in rotating machines are caused by faulty bearings. Thus failure alarm for the bearing system is often based on the detection of the onset of localized faults. Many methods are available for detecting faults in the bearing system. The majority of these methods assume that faults in bearings produce impulses. Impulse events can be attributed to bearing faults in the system. McFadden and Smith used the bandpass filter to filter the noise signal and then obtained the envelope by using the envelope detector. D. Ho and R. B Randall also tried envelope spectrum to detect faults in the bearing system, but it is very difficult to find resonant frequency in the noisy environments. S. -K. Lee and P. R. White used improved ANC (adaptive noise cancellation) to find faults. The basic idea of this technique is to remove the noise from the measured vibration signal, but they are not able to show the theoretical foundation of the proposed algorithms. Y.-H. Kim et al. used a moving window. This algorithm is quite powerful in the early detection of faults in a ball bearing system, but it is difficult to decide initial time and step size of the moving window. The early fault signal that is caused by microscopic cracks is commonly embedded in noise. Therefore, the success of detecting fault signal is completely determined by a method's ability to distinguish signal and noise. In 1969, Capon coined maximum likelihood (ML) spectra which estimate a mixed spectrum consisting of line spectrum, corresponding to a deterministic random process, plus arbitrary unknown continuous spectrum. The unique feature of these spectra is that it can detect sinusoidal signal from noise. Our idea

  6. Hotfire testing of a SSME HPOTP with an annular hydrostatic bearing

    Science.gov (United States)

    Nolan, Steven A.; Hibbs, Robert I.; Genge, Gary G.

    1994-01-01

    A new fluid film bearing package has been tested in the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP). This fluid film element functions as both the pump end bearing and the preburner pump rear wear ring seal. Most importantly, it replaces a duplex ball bearing package which has been the primary life limiting component in the turbopump. The design and predicted performance of the turbopump are reviewed. Results are presented for measured pump and bearing performance during testing on the NASA Technology Test Bed (TTB) Engine located at MSFC. The most significant results were obtained from proximity probes located in the bearing bore which revealed large subsynchronous precession at ten percent of shaft speed during engine start which subsided prior to mainstage power levels and reappeared during engine shutdown at equivalent power levels below 65% of nominal. This phenomenon has been attributed to rotating stall in the diffuser. The proximity probes also revealed the location of the bearing in the bore for different operating speeds. Pump vibration characteristics were improved as compared to pumps tested with ball bearings. After seven starts and more than 700 seconds of testing, the pump showed no signs of performance degradation.

  7. Severe wear behaviour of alumina balls sliding against diamond ceramic coatings

    Indian Academy of Sciences (India)

    ANURADHA JANA; NANDADULAL DANDAPAT; MITUN DAS; VAMSI KRISHNA BALLA; SHIRSHENDU CHAKRABORTY; RAJNARAYAN SAHA; AWADESH KUMAR MALLIK

    2016-04-01

    At present alumina is themost widely used bio-ceramic material for implants.However, diamond surface offers very good solid lubricant for different machinery, equipment including biomedical implants (hip implants, knee implants, etc.), since the coefficient of friction (COF) of diamond is lower than alumina. In this tribological study, alumina ball was chosen as the counter body material to show better performance of the polycrystalline diamond (PCD) coatings in biomedical load-bearing applications.Wear and friction data were recorded for microwave plasma chemical vapour deposition (MWCVD) grown PCD coatings of four different types, out of which two sampleswere as-deposited coatings, one was chemo-mechanically polished and the other diamond sample was made free standing by wet-chemical etching of the silicon wafer. The coefficient of friction of the MWCVD grown PCD against Al$_2$O$_3$ ball under dry ambient condition was found in the range of 0.29–0.7, but in the presence of simulated body fluid, the COF reduces significantly, in the range of 0.03–0.36. The samples were then characterized by Raman spectroscopy for their quality, by coherence scanning profilometer for surface roughness and by electron microscopy for their microstructural properties. Alumina balls worn out ($14.2 \\times 10^{−1}$ mm$^3$) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their bettertribological properties.

  8. Q-balls in atomic Bose-Einstein condensates

    CERN Document Server

    Enqvist, K

    2003-01-01

    Relativistic scalar field theories with a conserved global charge Q often possess (meta)stable spherically symmetric soliton solutions, called Q-balls. We elaborate on the perfect formal analogy which exists between Q-balls, and spherically symmetric solitons in certain non-relativistic atomic Bose-Einstein condensates, for which the dominant interatomic interaction can be tuned attractive. The stability of such atomic Q-balls depends on higher-order interatomic interactions, which can render the Q-balls absolutely stable for large Q. In a harmonic trap, present in existing experiments, the Q-ball solution is modified in an essential way. If the trap is significantly prolongated in one direction, however, then genuine solitons do appear, and some of the Q-ball properties studied in a relativistic cosmological context, such as their formation and collisions, can also be addressed experimentally.

  9. Magnetohydrodynamics equilibrium of a self-confined elliptical plasma ball

    International Nuclear Information System (INIS)

    A variational principle is applied to the problem of magnetohydrodynamics (MHD) equilibrium of a self-contained elliptical plasma ball, such as elliptical ball lightning. The principle is appropriate for an approximate solution of partial differential equations with arbitrary boundary shape. The method reduces the partial differential equation to a series of ordinary differential equations and is especially valuable for treating boundaries with nonlinear deformations. The calculations conclude that the pressure distribution and the poloidal current are more uniform in an oblate self-confined plasma ball than that of an elongated plasma ball. The ellipticity of the plasma ball is obviously restricted by its internal pressure, magnetic field, and ambient pressure. Qualitative evidence is presented for the absence of sighting of elongated ball lightning

  10. Arcturus and the Bears

    Science.gov (United States)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  11. The methodology of composing the exercises system with fit balls.

    Directory of Open Access Journals (Sweden)

    Voronov N.P.

    2011-02-01

    Full Text Available The original methodology of composing the exercises system with fit balls was considered. More than 10 publications were analysed. On the lesson with fit balls the problem was revealed. In the experiment took part 30 students at the age from 18 till 21. All the famous exercises were systematized. As a result, a big attractiveness and assimilability of the proposed complex was revealed. The effectiveness of the complex of physical exercises with fit balls for students was proved.

  12. LOW COMPRESSION TENNIS BALLS AND SKILL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    John Hammond

    2006-12-01

    Full Text Available Coaching aims to improve player performance and coaches have a number of coaching methods and strategies they use to enhance this process. If new methods and ideas can be determined to improve player performance they will change coaching practices and processes. This study investigated the effects of using low compression balls (LCBs during coaching sessions with beginning tennis players. In order to assess the effectiveness of LCBs on skill learning the study employed a quasi-experimental design supported by qualitative and descriptive data. Beginner tennis players took part in coaching sessions, one group using the LCBs while the other group used standard tennis balls. Both groups were administered a skills at the beginning of a series of coaching sessions and again at the end. A statistical investigation of the difference between pre and post-test results was carried out to determine the effect of LCBs on skill learning. Additional qualitative data was obtained through interviews, video capture and the use of performance analysis of typical coaching sessions for each group. The skill test results indicated no difference in skill learning when comparing beginners using the LCBs to those using the standard balls. Coaches reported that the LCBs appeared to have a positive effect on technique development, including aspects of technique that are related to improving power of the shot. Additional benefits were that rallies went on longer and more opportunity for positive reinforcement. In order to provide a more conclusive answer to the effects of LCBs on skill learning and technique development recommendations for future research were established including a more controlled experimental environment and larger sample sizes across a longer period of time

  13. Fourier-Laguerre transform, convolution and wavelets on the ball

    CERN Document Server

    McEwen, J D

    2013-01-01

    We review the Fourier-Laguerre transform, an alternative harmonic analysis on the three-dimensional ball to the usual Fourier-Bessel transform. The Fourier-Laguerre transform exhibits an exact quadrature rule and thus leads to a sampling theorem on the ball. We study the definition of convolution on the ball in this context, showing explicitly how translation on the radial line may be viewed as convolution with a shifted Dirac delta function. We review the exact Fourier-Laguerre wavelet transform on the ball, coined flaglets, and show that flaglets constitute a tight frame.

  14. Biomechanics of Heading a Soccer Ball: Implications for Player Safety

    OpenAIRE

    Charles F. Babbs

    2001-01-01

    To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumab...

  15. Accuracy and Reliability of a New Tennis Ball Machine

    OpenAIRE

    Cyril Brechbuhl, Grégoire Millet, Laurent Schmitt

    2016-01-01

    The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min-1. The initial frequency was 10 and increased by 2 until 22, then by 1 until 30...

  16. RELATIONSHIP BETWEEN MEDICINE BALL EXPLOSIVE POWER TESTS, THROWING BALL VELOCITY AND JUMP PERFORMANCE IN TEAM HANDBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Mourad Fathloun

    2011-04-01

    Full Text Available In this study, the relationships between medicine ball explosive power tests, jump and handball throwing velocity performance in team handball players were investigated. Explosive test was measured by a medicine ball throw. Specific explosive strength was evaluated by making 3 types of overarm throw: standing position, using an adapted chair (without run-up, T w , a 3-step running throw (T 3-Steps and a jump shot (J S . The jump test (SJ, CMJ and FCMJ were determined using the OptoJump. The medicine ball explosive power test was closely related to T 3-Steps . Significant relationships were observed between medicine ball explosive power tests and (J S and (T w . The Medicine ball explosive power test is also positively related to vertical jump ability represented by Squat Jump (SJ and Countermovement Jump (CMJ. The results suggest an association of the medicine ball explosive power tests to performance in throwing events

  17. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  18. Tar ball Monitoring Along the Kenyan Beaches.

    OpenAIRE

    Nguta, M.

    1993-01-01

    Observations and measurements of petroleum tar balls on a number of Kenyan beaches were carried out between 1979 and 1982. A large variation in the size and amount of tar deposit at the beaches was recorded. These values ranged from very small pebbles to large lumps of 30 cm in diameter, weighing up to 1.5 kg. The average tar loading during the sampling period ranged from 0-18 g/m2. Between 25-50% by weight of the tar lumps were shell fragments, sand and other nonpetroleum debris. The chemica...

  19. A proposed experiment on ball lightning model

    International Nuclear Information System (INIS)

    Highlights: → We propose to put a glass sphere inside an excited gas. → Then to put a light ray inside the glass in a whispering gallery mode. → If the light is resonant to gas excitation, it will be amplified at every reflection. → In ms time the light in the glass will be amplified, and will melt the glass. → A liquid shell kept integer by electrostriction forces is the ball lightning model. -- Abstract: We propose an experiment for strong light amplification at multiple total reflections from active gaseous media.

  20. Collective flow measured with the Plastic Ball

    International Nuclear Information System (INIS)

    The experimental results from the Plastic Ball detector have contributed vastly to the understanding of the reaction mechanism of nuclear collisions at several hundred MeV per nucleon. The discovery of the collective flow phenomena (bounce-off of spectator fragments, side-splash in the reaction plane, and squeeze-out out of the reaction plane), as they were predicted by hydrodynamical models, has led to the experimental observation of compressed nuclear matter, which is a necessary condition before one can study the equation of state in detail and search for phase transitions at higher energies. 39 refs., 9 figs., 1 tab

  1. Crystal Ball evidence for new states

    International Nuclear Information System (INIS)

    Evidence for three new particles observed in the Crystal Ball detector is presented. The first particle, at 3592 MeV, is seen inclusively in γ transitions from psi', and is thus a candidate for eta/sub c/'. The other two, at 1440 and 1640 MeV, are best seen in exclusive decays of psi involving a prompt γ, and are thus candidates for bound states of two gluons. Detailed reasons are presented to support the contention that these states are distinct from previously observed candidates such as E(1420). Alternative hypotheses are discussed

  2. Early diagenetic high-magnesium calcite and dolomite indicate that coal balls formed in marine or brackish water: Stratigraphic and paleoclimatic implications

    Science.gov (United States)

    Raymond, Anne

    2016-04-01

    and experience significant evaporation. Paleotropical coals with coal balls are under- and overlain by siliciclastic sediments, and, if fresh, would have required ever-wet climatic conditions for peat to accumulate. Pervasive freshwater diagenesis, with low magnesium calcite enveloping individual grains of high-magnesium calcite, results in most coal-ball carbonates having a freshwater or mixed isotopic signature. In some coal balls, cell walls in the root cortex (a soft tissue) separate carbonate of differing magnesium content, resulting in cells filled with low-magnesium (freshwater) calcite adjacent to cells filled with high-magnesium (marine) calcite, suggesting that these cements formed in recently dead or dying roots. The juxtaposition of high-magnesium (marine) calcite and low-magnesium (freshwater) calcite in coal balls suggests that they formed at the marine/freshwater interface in mires that contained salt-tolerant plants. This model of coal-ball formation suggests that coals bearing coal balls accumulated early in marine transgression as glaciers melted and sea level rose. In modern coastal mires, tidal incursion of salt water can maintain high freshwater tables, enabling domed freshwater peat to form in climates that normally would be too dry for tropical freshwater peat accumulation. Peat accumulation in these mires may be due to marine transgression rather than the ever-wet paleoclimates.

  3. Rolling-contact fatigue resistance of hard coatings on bearing steels.

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.

    1999-08-18

    Ball- and roller-bearings of the 21st Century are expected to perform better and last longer while operating under more stringent conditions than before. To meet these great expectations, researchers have been constantly exploring new bearing designs or refining existing ones, optimizing microstructure and chemistry of bearing materials, and alternatively, they have been considering the use of thin hard coatings for improved bearing performance and durability. Already, some laboratory tests have demonstrated that hard nitride, carbide (such as TiN, TiC, etc.) and diamondlike carbon (DLC) coatings can be very effective in prolonging the fatigue lives of bearing steels. This paper provides an overview of the recent developments in hard coatings for bearing applications. Previous studies have demonstrated that thin, hard coatings can effectively prolong the fatigue lives of bearing steel substrates. In particular, thinner hard coatings (i.e., 0.2 - 1 {micro}m thick) provide exceptional improvements in the fatigue lives of bearing steel substrates. In contrast, thicker hard coatings suffer micro fracture and delamination when tested under high contact stresses, hence are ineffective and may even have a negative effect on bearing life. Overall, it was concluded that thin hard coatings may offer new possibilities for bearing industry in meeting the performance and durability needs of the 21st Century.

  4. 76 FR 45853 - Certain Bearings From China, France, Germany, and Italy; Institution of Five-Year Reviews...

    Science.gov (United States)

    2011-08-01

    ... from China (52 FR 22667). On May 15, 1989, Commerce issued antidumping duty orders on imports of ball bearings from France, Germany, and Italy (54 FR 20900, 20902, and 20903). Following first and second five... amended at 74 FR 2847 (January 16, 2009). \\1\\ No response to this request for information is required if...

  5. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  6. Application of powder metallurgy techniques to produce improved bearing elements for liquid rocket engines

    Science.gov (United States)

    Moracz, D. J.; Shipley, R. J.; Moxson, V. S.; Killman, R. J.; Munson, H. E.

    1992-01-01

    The objective was to apply powder metallurgy techniques for the production of improved bearing elements, specifically balls and races, for advanced cryogenic turbopump bearings. The materials and fabrication techniques evaluated were judged on the basis of their ability to improve fatigue life, wear resistance, and corrosion resistance of Space Shuttle Main Engine (SSME) propellant bearings over the currently used 440C. An extensive list of candidate bearing alloys in five different categories was considered: tool/die steels, through hardened stainless steels, cobalt-base alloys, and gear steels. Testing of alloys for final consideration included hardness, rolling contact fatigue, cross cylinder wear, elevated temperature wear, room and cryogenic fracture toughness, stress corrosion cracking, and five-ball (rolling-sliding element) testing. Results of the program indicated two alloys that showed promise for improved bearing elements. These alloys were MRC-2001 and X-405. 57mm bearings were fabricated from the MRC-2001 alloy for further actual hardware rig testing by NASA-MSFC.

  7. Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications

    Science.gov (United States)

    DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.

    2009-01-01

    An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding contact applications such as bearings and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among bearing materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other bearing alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace bearing alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision bearings, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C bearing balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated contacting conditions.

  8. Management recommendations: Bear River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Bear River Migratory Bird Refuge, by a land use specialist. Recommendations, time frame and additional...

  9. Automated diagnosis of rolling bearings using MRA and neural networks

    Science.gov (United States)

    Castejón, C.; Lara, O.; García-Prada, J. C.

    2010-01-01

    Any industry needs an efficient predictive plan in order to optimize the management of resources and improve the economy of the plant by reducing unnecessary costs and increasing the level of safety. A great percentage of breakdowns in productive processes are caused by bearings. They begin to deteriorate from early stages of their functional life, also called the incipient level. This manuscript develops an automated diagnosis of rolling bearings based on the analysis and classification of signature vibrations. The novelty of this work is the application of the methodology proposed for data collected from a quasi-real industrial machine, where rolling bearings support the radial and axial loads the bearings are designed for. Multiresolution analysis (MRA) is used in a first stage in order to extract the most interesting features from signals. Features will be used in a second stage as inputs of a supervised neural network (NN) for classification purposes. Experimental results carried out in a real system show the soundness of the method which detects four bearing conditions (normal, inner race fault, outer race fault and ball fault) in a very incipient stage.

  10. 78 FR 29702 - Ball Bearings and Parts Thereof From Germany: Final Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2013-05-21

    ... Results of Sunset Reviews and Revocation of Antidumping Duty Orders, 76 FR 57019, (September 15, 2011... Antidumping Duty Administrative Review and Partial Rescission; 2011- 2011, 78 FR 9764 (February 11, 2013... Duty Proceedings; Final Modification, 77 FR 8101 (February 14, 2012) (Final Modification)....

  11. 78 FR 9674 - Ball Bearings and Parts Thereof From Germany: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2013-02-11

    ... Results of Sunset Reviews and Revocation of Antidumping Duty Orders, 76 FR 57019, (September 15, 2011... in Certain Antidumping Proceedings: Final Modification, 77 FR 8101, 80102 (February 14, 2012). The... Duties, 68 FR 23954 (May 6, 2003). For the companies which are not selected for individual...

  12. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  13. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  14. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  15. Physical Activity Benefits Creativity: Squeezing a Ball for Enhancing Creativity

    Science.gov (United States)

    Kim, JongHan

    2015-01-01

    Studies in embodied cognition show that physical sensations, such as touch and movement, influence cognitive processes. Two studies were conducted to test whether squeezing a soft versus a hard ball facilitates different types of creativity. Squeezing a malleable ball would increase divergent creativity by catalyzing multiple or alternative ideas,…

  16. On a Simple Formulation of the Golf Ball Paradox

    Science.gov (United States)

    Pujol, O.; Perez, J. Ph.

    2007-01-01

    The motion of a ball rolling without slipping on the lateral section inside a fixed vertical cylinder is analysed in the Earth referential frame which is assumed to be Galilean. Equations of motion are rapidly obtained and the golf ball paradox is understood: these equations describe a motion consisting of a vertical harmonic oscillation related…

  17. A Machine Vision System for Ball Grid Array Package Inspection

    Institute of Scientific and Technical Information of China (English)

    XIA Nian-jiong; CAO Qi-xin; LEE Jey

    2005-01-01

    An optical inspection method of the Ball Grid Array package (BGA) was proposed by using a machine vision system. The developed machine vision system could get main critical factors for BGA quality evaluation, such as the height of solder ball, diameter, pitch and coplanarity. The experiment has proved that this system is available for BGA failure detection.

  18. [First clinical experiences with ceramic ball attachments for overdentures].

    Science.gov (United States)

    Büttel, Adrian E; Schmidli, Fredy; Marinello, Carlo P; Lüthy, Heinz

    2008-01-01

    In this prospective clinical study on 40 patients with similar clinical conditions (edentulous jaw with 2 interforaminal implants) commercially available ceramic ball attachments (ruby) were compared to commercial titanium ball attachments. The primary aim of the study was to measure the wear of the ball attachments after being 1 year in function. However, in the course of the study already after 7 to 12 months multiple failures with ceramic ball attachments occurred. Twelve (28%) of 43 ceramic ball attachments had to be replaced, mostly because of fractures (8) of the ceramic ball. It seems that ceramic ball attachments of the investigated design are not able to withstand normal intraoral stresses. The short-term susceptibility to fractures didn't allow to examine the ceramic-inherent features such as compressive strength and wear resistance. Furthermore, a secure connection between a titan base and a ceramic ball seems to be challenging. Based on these results, in implant-retained removable prosthesis the use of metal-based retainers is still recommended, although during maintenance a higher wear has to be expected. This wear can be compensated by either activating or changing the matrix or the patrix. PMID:18293602

  19. Dynamics of Q-balls in an expanding universe

    International Nuclear Information System (INIS)

    We analyze the evolution of light Q-balls in a cosmological background, and find a number of interesting features. For Q-balls formed with a size comparable to the Hubble radius, we demonstrate that there is no charge radiation, and that the Q-ball maintains a constant physical radius. Large expansion rates cause charge migration to the surface of the Q-ball, corresponding to a nonhomogeneous internal rotation frequency. We argue that this is an important phenomenon as it leads to a large surface charge and possible fragmentation of the Q-ball. We also explore the deviation of the Q-ball profile function from the static case. By introducing a parameter ε, which is the ratio of the Hubble parameter to the frequency of oscillation of the Q-ball field, and using solutions to an analytically approximated equation for the profile function, we determine the dependence of the new features on the expansion rate. This allows us to gain an understanding of when they should be considered and when they can be neglected, thereby placing restrictions on the existence of homogeneous Q-balls in expanding backgrounds

  20. The Net Physiological Cost of Dribbling a Soccer Ball.

    Science.gov (United States)

    Reilly, Thomas; Ball, David

    1984-01-01

    To establish the net energy cost of dribbling a soccer ball, eight males ran on a treadmill while dribbling a ball against a rebound box. Oxygen uptake, perceived exertion, and blood lactate levels were measured and compared with results from subjects running without dribbling. Results are discussed. (Author/DF)

  1. Electrochemical corrosion of steel balls in wet grinding

    Institute of Scientific and Technical Information of China (English)

    谢恒星; 李松仁; 李定或

    2003-01-01

    Rest potentials for the steel ball electrode and the pyrite electrode as well as the combination potentials and the galvanic currents developed in the pyrite-steel ball couple were measured. The data demonstrate that the galvanic couples are going to form between the pyrite particles and the steel balls when they contact with each other. The initial combination potential and the initial galvanic current of the pyrite-ball couple while bubbling with oxygen are greater than those in aeration of air. The combination potential and the galvanic current decrease more quickly with time while bubbling with oxygen than they do in aeration of air. In an experiment of simulating wear differences, a galvanic current, which is smaller than that developed in the pyrite-ball couple, exists between two different ball electrodes in wear degree on the surface of them. Under different grinding time conditions, the equivalent corrosion current density calculated from marked ball wear data by applying Faraday's law correlates well with those estimated from polarization curves of pyrite and ball electrodes, and the former is always greater than the latter.

  2. Launch Creativity with Ping-Pong Ball Challenge

    Science.gov (United States)

    Kornoelje, Joanne; Roman, Harry T.

    2011-01-01

    Educators at Thomas A. Edison Middle School have worked together to bring invention information and activities to life. One activity in particular, Ping-Pong Ball Invention Challenge, has proven a great success. The Ping-Pong Ball Invention Challenge was inspired by the basic rules for PBS's "Design Squad"'s "Pop Fly" activity. In this article,…

  3. Motion of a Ball on a Moving Surface

    Science.gov (United States)

    Cross, Rod

    2016-01-01

    A well-known physics demonstration is to pull a tablecloth rapidly from under some crockery without disturbing the crockery. An interesting question is whether the same result can be expected if the crockery is replaced by a ball, given that the ball might roll backwards on the tablecloth. Theoretical and experimental results are presented showing…

  4. Structure and magnetism of SmCo5 nanoflakes prepared by surfactant-assisted ball milling with different ball sizes

    International Nuclear Information System (INIS)

    Anisotropic magnetic SmCo5 nanoflakes have been fabricated by surfactant-assisted ball milling (SABM) using hardened steel balls of one of the following sizes: 4, 6.5, 9.5 and 12.7 mm in diameters. The magnetic properties of SmCo5 particles prepared by SABM with different milling ball sizes in diameters were investigated systematically. It was showed that the nanoflakes milled by amount of small size balls had a higher coercivity and lower anisotropy, i.e., worse grain orientation although in a short milling time while the nanoflakes prepared with same weight of big balls tend to have a lower coercivity, better grain orientation. The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning. The SEM analysis shows that the morphology of nanoflakes prepared with different ball sizes are almost the same when the balls to powder weight ratio is fixed. The different magnetic properties caused by different ball sizes are mainly due to the different microstructure changes, i.e, grain refinement and c-axis orientation, which are demonstrated by X-ray diffraction (XRD) analysis and transmission electron microscope (TEM). Based on the experiments above, a combined milling process was suggested and done to improve magnetic properties as your need. - Highlights: • We fabricated anisotropic magnetic SmCo5 nanoflakes by surfactant-assisted ball milling (SABM). • We investigated the magnetic properties of SmCo5 particles systematically. It was showed that the coercivity, high or low, and grain orientation, good or bad, were influenced strongly by balls size. The different magnetisms caused by different ball sizes is mainly due to the different microstructure changes. • The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning

  5. A comprehensive dynamic model to investigate the stability problems of the rotor-bearing system due to multiple excitations

    Science.gov (United States)

    Zhang, Xuening; Han, Qinkai; Peng, Zhike; Chu, Fulei

    2016-03-01

    In this paper, a comprehensive dynamic model is proposed to analyze the dynamic behaviors of the rotor-bearing system. Three types of excitation including the bearing waviness, the unbalanced force and the finite number of balls (varying compliance effect) are considered. Based on the extended Jones-Harris model with five degrees of freedom, the load distribution and then the stiffness of the angular contact ball bearing are obtained theoretically. After introducing the three types of excitation into the model, the bearing stiffness matrix becomes time-varying and many parametric frequencies are found due to the multiple excitations. Then, the stability problems of the parametrically excited rotor-bearing system are investigated utilizing the discrete state transition matrix method (DSTM). The simple instability regions arising from the translational and the angular motions are analyzed respectively. The effects of the amplitude and the initial phase angle of the bearing waviness, the rotor eccentricity, the bearing preload and the damping of the rotating system on the instability regions are discussed thoroughly. It is shown that the waviness amplitudes have significant influences on the instability regions, while the initial phase angles of the waviness almost have no effect on the instability regions. The rotor eccentricity just affects the widths of the instability regions. The increasing of the bearing preload only shifts the positions of the instability regions. Damping could reduce the instability regions but it could not diminish the regions completely.

  6. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  7. 60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications

    Science.gov (United States)

    DellaCorte, Christopher; Jefferson, Michael

    2015-01-01

    NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

  8. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  9. Two balls and a string: from ordered motion to chaos

    International Nuclear Information System (INIS)

    Two spherical balls are connected by a taught string passing through a small hole in a perfectly planar table: the first ball, subject to a central force, moves without friction on a two-dimensional plane, while the second ball moves only along the vertical axis directly below the hole. The pedagogical aspects of this novel two-body problem are given particular attention: Newton’s laws, central force motion, conservation laws, angular momentum, constraints, etc. The dynamics of the system is considered under various initial conditions wherein the ball on the table moves qualitatively in rotating ellipses or hypotrochoids. The conditions for closed or periodic orbits are examined. The more complex case of the inclined plane is then considered, revealing a rich variety of periodic, aperiodic and chaotic solutions as a function of the ball mass ratio and the plane inclination angle. The associated Poincaré phase-space maps are discussed. (paper)

  10. Bearing and retention apparatus for a camshaft phase change device

    Energy Technology Data Exchange (ETDEWEB)

    Danieli, O.G.

    1992-10-06

    This patent describes a phase change device. It comprises: an output member, in input member, bearing means supporting the input member for rotation on the output member, an advancing member received between the input and output member and being operative upon axial movement thereof to effect limited relative rotation between the input and output member, drum means engaged with the advancing member to effect the axial movement of the advancing member when a retarding force is applied to the drum means, and actuating means operable to apply the retarding force. This patent describes improvement in the bearing means. It comprises a first peripheral groove formed in the input member, a second peripheral groove formed in the output member, and a plurality of balls received in the first and second grooves.

  11. Accuracy and Reliability of a New Tennis Ball Machine

    Directory of Open Access Journals (Sweden)

    Cyril Brechbuhl, Grégoire Millet, Laurent Schmitt

    2016-06-01

    Full Text Available The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min-1. The initial frequency was 10 and increased by 2 until 22, then by 1 until 30 balls·min-1. The reference points for the impact were 8.39m from the net and 2.70m from lateral line for the right side and 2.83m for the left side. The precision of the machine was similar on the right and left sides (0.63 ± 0.39 vs 0.63 ± 0.34 m. The distances to the reference point were 0.52 ± 0.42, 0.26 ± 0.19, 0.52 ± 0.37, 0.28 ± 0.19 m for the Y-right, X-right, Y-left and X-left impacts. The precision was constant and did not increase with the intensity. (e.g ball frequency. The ball velocity was 86.3 ± 1.5 and 86.5 ± 1.3 km·h-1 for the right and the left side, respectively. The coefficient of variation for the velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min-1. Conclusion: both the accuracy and the reliability of this new ball machine appear satisfying enough for field testing and training.

  12. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  13. The spectacle of the ball python

    DEFF Research Database (Denmark)

    Da Silva, Mari-Ann Otkjær; Heegaard, Steffen; Wang, Tobias;

    2014-01-01

    A detailed morphological description of the spectacle of the ball python (Python regius) is provided. The eyes of 21 snakes were examined by light microscopy and/or transmission electron microscopy. Additionally, eyes of nine live snakes were examined using optical coherence tomography (OCT) and...... inner epithelium holds squamous cells containing vesicles and microvilli. At the rim of the spectacle, there is a transition zone, where the spectacle merges with the epidermis and dermis of the periocular scales. This zone is characterized by a greater height of the basal cells of the outer epithelium...... and a less orderly organization of the stroma compared with the spectacle proper. The thickness of the spectacle was uniform throughout. It averaged 96 ± 10 µm in histological specimens and 108 ± 13 µm using OCT. The subspectacular space was extremely narrow in the live snakes; however, the space was...

  14. Local properties of maps of the ball

    Directory of Open Access Journals (Sweden)

    Yakar Kannai

    2003-01-01

    Full Text Available Let f be an essential map of Sn−1 into itself (i.e., f is not homotopic to a constant mapping admitting an extension mapping the closed unit ball B¯n into ℝn. Then, for every interior point y of Bn, there exists a point x in f−1(y such that the image of no neighborhood of x is contained in a coordinate half space with y on its boundary. Under additional conditions, the image of a neighborhood of x covers a neighborhood of y. Differential versions are valid for quasianalytic functions. These results are motivated by game-theoretic considerations.

  15. Ball-like inorganic ion exchangers

    International Nuclear Information System (INIS)

    Presented are the results of works aimed at developing the method of obtaining ball-shaped inorganic ion exchangers with suitable exchange and mechanical properties. Satisfactory results have been obtained at using the sol-gel method, which is characterized by its product of spherical particles. The preparation method of hydrooxidic gels of aluminium, chromium, iron, silicon, germanium, titanium, zirconium, tin, niobium, tantalum, thorium and uranium has been mastered. By the gel conversion of hydrooxidic character, low-soluble compounds, possessing ion exchange properties have been prepared. Among them, phosphates, ferrocyanides, sulfides, molybdates, vanadates are of special significance. Cesium capture on zirconium phosphate, possessing interesting properties from the veiwpoint of nuclear technique, has been considered in detail

  16. Are perytons signatures of ball lightning?

    International Nuclear Information System (INIS)

    The enigmatic downchirped signals, called 'perytons', that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  17. A Theoretical Analysis of Ball Spinning

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    As a special method of manufacturing thin wall tubes, the ball spinning process has been used for nearly 30 years because of its less investment of equipment, higher precision, and more perfect properties of products. However, the application is limited since the process parameters are determined based on empirical data and laboratory experiments for lack of a whole theoretical analysis. In this paper, some basic parameters such as the force and power parameters have been studied based on an analysis of geometry and mechanics of the process. The calculation of forming forces and the selection of the working angle are carried out. At the end, a perfect comparison between the results of the experiments and the theoretical analysis is made.

  18. Recent results from the Crystal Ball

    International Nuclear Information System (INIS)

    During the past year, the Crystal Ball experiment has continued the investigation of e+e- interactions at SPEAR. In the course of the year, we have slightly more than doubled the available datasets at the J/psi (to 2.2 x 106 produced J/psi) and the psi' (to 1.8 x 106 produced psi') resonances, and have increased the data in the 5.2 to 7.4 GeV center-of-mass (E/sub c.m./) region. The present discussion is limited to recent results obtained with the J/psi and psi' datasets, primarily dealing with transitions among the charmonium bound states

  19. Non-compact Torsion Free Ball Quotients

    CERN Document Server

    Kasparian, Azniv

    2012-01-01

    The present note specifies the Kodaira-Enriques classification type of a non-compact torsion free ball quotient ${\\mathbb B} / \\Gamma$. It turns out that ${\\mathbb B} / \\Gamma$ can be birational to a non-simple abelian surface, to an elliptic fibration of Kodaira dimension 1 with base of genus $\\leq 1$ or to a minimal surface of general type. The argument makes use of the embedding of the fundamental group $\\pi_1(T_i)$ of a smooth elliptic irreducible component $T_i$ of the toroidal compactifying divisor $T= ({\\mathbb B} / \\Gamma)' \\setminus ({\\mathbb B} / \\Gamma)$ in the fundamental group $\\pi_1 (X')$ of the toroidal compactification $X'= ({\\mathbb B} / \\Gamma)$. The note elaborates also on various consequences of the Kobayashi non-hyperbolicity of $X'$ and the Kobayashi hyperbolicity of $ {\\mathbb B} / \\Gamma$.

  20. Active vibration control of a rotor-bearing system based on dynamic stiffness

    OpenAIRE

    Andrés Blanco Ortega; Francisco Beltrán Carbajal; Gerardo Silva Navarro; Marco Antonio Oliver Salazar

    2010-01-01

    This paper presents an active vibration control scheme to reduce unbalance induced synchronous vibration in rotorbearing systems supported on two ball bearings, one of which can be automatically moved to control the effective rotor length and, as an immediate consequence, the rotor stiffness. This dynamic stiffness control scheme, based on frequency analysis, speed control and acceleration scheduling, is used to avoid resonant vibration of a rotor system when it passes (runup or coast down) t...

  1. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  2. Blood Pump Bearing System

    Science.gov (United States)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  3. Tribological performance of ceramic coatings deposited on metal surfaces for micro-bearing biomedical applications

    International Nuclear Information System (INIS)

    Modification of metal materials by means of ceramic coating deposition is an effective way of forming alternative bearing surfaces. Ceramic AlN, Al2O3 and nanocomposite oxynitride coatings are widely used as protective coatings against wear, diffusion and corrosion. The enhancement of the mechanical properties, such as hardness parameters, effective Young's modulus, toughness, elastic recovery and wear resistance of the coatings, is very important for the tribological performance of the next generation of ceramic-coated ball bearing devices.

  4. Friction moment analysis of space gyroscope bearing with ribbon cage under ultra-low oscillatory motion

    OpenAIRE

    Jiang Shaona; Chen Xiaoyang; Gu Jiaming; Shen Xuejin

    2014-01-01

    This paper presents the model of calculating the total friction moment of space gyroscope ball bearings which usually work under ultra-low oscillatory motion and are very sensitive to the friction moment. The aim is to know the proportion of the friction moment caused by each frictional source in the bearing’s total friction moment, which is helpful to optimize the bearing design to deduce the friction moment. In the model, the cage dynamic equations considering six degree-of-freedom and the ...

  5. Modular gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  6. Water Bouncing Balls: how material stiffness affects water entry

    Science.gov (United States)

    Truscott, Tadd

    2014-03-01

    It is well known that one can skip a stone across the water surface, but less well known that a ball can also be skipped on water. Even though 17th century ship gunners were aware that cannonballs could be skipped on the water surface, they did not know that using elastic spheres rather than rigid ones could greatly improve skipping performance (yet would have made for more peaceful volleys). The water bouncing ball (Waboba®) is an elastic ball used in a game of aquatic keep away in which players pass the ball by skipping it along the water surface. The ball skips easily along the surface creating a sense that breaking the world record for number of skips could easily be achieved (51 rock skips Russell Byers 2007). We investigate the physics of skipping elastic balls to elucidate the mechanisms by which they bounce off of the water. High-speed video reveals that, upon impact with the water, the balls create a cavity and deform significantly due to the extreme elasticity; the flattened spheres resemble skipping stones. With an increased wetted surface area, a large hydrodynamic lift force is generated causing the ball to launch back into the air. Unlike stone skipping, the elasticity of the ball plays an important roll in determining the success of the skip. Through experimentation, we demonstrate that the deformation timescale during impact must be longer than the collision time in order to achieve a successful skip. Further, several material deformation modes can be excited upon free surface impact. The effect of impact velocity and angle on the two governing timescales and material wave modes are also experimentally investigated. Scaling for the deformation and collision times are derived and used to establish criteria for skipping in terms of relevant physical parameters.

  7. Failure Diagnosis System for a Ball-Screw by Using Vibration Signals

    Directory of Open Access Journals (Sweden)

    Won Gi Lee

    2015-01-01

    Full Text Available Recently, in order to reduce high maintenance costs and to increase operating ratio in manufacturing systems, condition-based maintenance (CBM has been developed. CBM is carried out with indicators, which show equipment’s faults and performance deterioration. In this study, indicator signal acquisition and condition monitoring are applied to a ball-screw-driven stage. Although ball-screw is a typical linearly reciprocating part and is widely used in industry, it has not gained attention to be diagnosed compared to rotating parts such as motor, pump, and bearing. First, the vibration-based monitoring method, which uses vibration signal to monitor the condition of a machine, is proposed. Second, Wavelet transform is used to analyze the defect signals in time-frequency domain. Finally, the failure diagnosis system is developed using the analysis, and then its performance is evaluated. Using the system, we estimated the severity of failure and detect the defect position. The low defect frequency (≈58.7 Hz is spread all over the time in the Wavelet-filtered signal with low frequency range. Its amplitude reflects the progress of defect. The defect position was found in the signal with high frequency range (768~1,536 Hz. It was detected from the interval between abrupt changes of signal.

  8. The effect of surface geometry on soccer ball trajectories

    OpenAIRE

    Barber, S.; Carré, M.J.

    2010-01-01

    Two different measurement techniques are used to examine the effect of surface geometry on soccer ball trajectories. Five professional players are observed using high-speed video when taking curling free kicks with four different soccer balls. The input conditions are measured and the average launch velocity and spin are found to be approximately 24 m/s and 106 rad/s. It is found that the players can apply more spin (~50%) on average to one ball, which has a slightly rougher surface than the ...

  9. [Locator or ball attachment: a guide for clinical decision making].

    Science.gov (United States)

    Büttel, Adrian E; Bühler, Nico M; Marinello, Carlo P

    2009-01-01

    Various attachments are available to retain overdentures on natural roots or implants. Technical aspects, the clinical handling, the capability to adapt or repair and the costs are parameters to be considered when choosing the appropriate attachment. Ball attachments and bars are clinically established and well documented. Ball attachments as prefabricated, unsplinted units are easily replaceable and show hygienic advantages, while bars show favorable stability. The Locator is a newer, popular clinical alternative to these established attachments. The ball attachment and the Locator are compared from a technical and clinical point of view. PMID:19852208

  10. Locally Optimal Confidence Ball for a Gaussian Mixture Random Variable

    OpenAIRE

    Sendorek, Pierre; Charbit, Maurice; Abed-Meraim, Karim; Legoll, Sébastien

    2013-01-01

    We address the problem of finding an estimator such as its associated confidence ball is the smallest possible in the case where the probability density function of the true position (or of the parameter to estimate) is a d-dimensional Gaussian mixture. As a solution, we propose a steepest descent algorithm which optimizes the position of the center of a ball such as its radius decreases at each step but still ensures that the ball centered on the optimized position contains the given probabi...

  11. A simple alternative to the Crystal Ball function

    CERN Document Server

    Das, Souvik

    2016-01-01

    We present a simple alternative to the Crystal Ball function that has an exponential tail stitched to a Gaussian core. It has one parameter less than the Crystal Ball function and, where appropriate, offers more stable fits to peaks that continue into exponential tails. The function may also be extended with two exponential tails on each side of the Gaussian, and this has two parameters less than the corresponding double-shouldered Crystal Ball function. This function has been used to model background and signal processes in a recent Higgs pair production search and may be of versatile use in experimental physics and other fields.

  12. Gas-discharge particle detector with ball-tipped anodes

    International Nuclear Information System (INIS)

    A new gas-discharge particle detector, whose anode is a set of balls 2mm in diameter is investigated. The chamber is blowing down by the argon-methane-methylal gas mixture with the ratio 3:1:1. The detector operates in the self-quenching streamer mode, has high efficiency and a wide counting characteristic plateau. The maximum counting rate of particles at one ball is ∼ 2.5x104 s-1. The ball-tipped anodes allow making reliable complex-shaped detectors. Two-coordinate detection of multiparticle events can be naturally organized in detectors like that

  13. Destruction of weapons-grade plutonium with pebble bed type HTGRs using burner balls and breeder balls

    International Nuclear Information System (INIS)

    As the method of disposing the plutonium coming from disassembled weapons, the method of burning the fuel in which the plutonium is mixed with a parent material in LWRs or the disposal by glass solidification is proposed. In the former method, it is desirable to do the reprocessing of spent fuel for effectively utilizing fission products. The latter method needs watch against the diversion of the plutonium. The authors devised the method of effectively annihilating plutonium by separating into the burner balls of plutonium and the breeder balls of a parent material, and burning those by mixing in a pebble bed type high temperature gas-cooled reactor, while continuously exchanging them. It was clarified from the aspect of nuclear characteristics that by using this method, 239Pu can be annihilated to the state of enabling the direct abandonment without reprocessing. The flow of burner balls and breeder balls in the reactor is shown, and multi-pass fuel exchange method was adopted to burn Pu in burner balls up. The rate of Pu annihilation was determined by the change of the amount of Pu for the burnup evaluated by lattice burning calculation. The maximum amount of Pu charge in one burner ball is limited by the maximum allowable power output of burner balls. (K.I.)

  14. Comparison of Life Theories for Rolling-Element Bearings

    Science.gov (United States)

    Zaretsky, Erwin V.; Poplawski, Joseph V.; Peters, Steven M.

    1995-01-01

    Nearly five decades have passed since G. Lundberg and A. Palmgren published their life theory in 1947 and 1952 and it was adopted as an ANSI/ABMA and ISO standard in 1950 and 1953. Subsequently, many variations and deviations from their life theory have been proposed, the most recent being that of E. Ioannides and T.A. Harris in 1985. This paper presents a critical analysis comparing the results of different life theories and discussing their implications in the design and analysis of rolling-element bearings. Variations in the stress-life relation and in the critical stress related to bearing life are discussed using stress fields obtained from three-dimensional, finite-element analysis of a ball in a nonconforming race under varying load. The results showed that for a ninth power stress-life exponent the Lundberg-Palmgren theory best predicts life as exhibited by most air-melted bearing steels. For a 12th power relation reflected by modern bearing steels, a Zaretsky-modified Weibull equation is superior. The assumption of a fatigue-limiting stress distorts the stress-life exponent and overpredicts life.

  15. Development of Flexible Bearing

    Directory of Open Access Journals (Sweden)

    K.S.Mohanraj

    2014-06-01

    Full Text Available Elastomeric base isolation systems are proven to be effective in reducing seismic forces transmitted to buildings. However, due to their cost, the use of these devices is currently limited to large and expensive buildings. A fiber reinforced elastomeric isolator utilizes fiber fabric, such as carbon fiber, glass fibre, and etc. as the reinforcement material instead of solid steel plates. The fibre fabric reinforcement is extensible in tension and has no flexural rigidity. Elastomers normally used in the isolator are natural rubber; neoprene, butyl rubber and nit rile rubber etc. These devices were fabricated by binding alternating layers of rubber and fibre mesh. The fibre mesh is used to increase the vertical stiffness of the bearings while maintaining low lateral stiffness. Characterizing the behaviour of a fibre reinforced bearing “shape factor” of the bearing, Poisson’s ratio of the elastomeric material and flexibility of the reinforcing sheets and investigate the effect of reinforcement flexibility on compressive behaviour of elastomeric bearings with different geometrical and material properties. Bonding with fibre reinforcements can increase the stiffness of elastic layers only when the elastic layer is compressed.

  16. Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis (Chip) E., III

    2014-01-01

    Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings.

  17. Recalibrated Equations for Determining Effect of Oil Filtration on Rolling Bearing Life

    Science.gov (United States)

    Needelman, William M.; Zaretsky, Erwin V.

    2014-01-01

    In 1991, Needelman and Zaretsky presented a set of empirically derived equations for bearing fatigue life (adjustment) factors (LFs) as a function of oil filter ratings. These equations for life factors were incorporated into the reference book, "STLE Life Factors for Rolling Bearings." These equations were normalized (LF = 1) to a 10-micrometer filter rating at Beta(sub x) = 200 (normal cleanliness) as it was then defined. Over the past 20 years, these life factors based on oil filtration have been used in conjunction with ANSI/ABMA standards and bearing computer codes to predict rolling bearing life. Also, additional experimental studies have been made by other investigators into the relationship between rolling bearing life and the size, number, and type of particle contamination. During this time period filter ratings have also been revised and improved, and they now use particle counting calibrated to a new National Institute of Standards and Technology (NIST) reference material, NIST SRM 2806, 1997. This paper reviews the relevant bearing life studies and describes the new filter ratings. New filter ratings, Beta(sub x(c)) = 200 and Beta(sub x(c)) = 1000, are benchmarked to old filter ratings, Beta(sub x) = 200, and vice versa. Two separate sets of filter LF values were derived based on the new filter ratings for roller bearings and ball bearings, respectively. Filter LFs can be calculated for the new filter ratings.

  18. Detection of Bearing Faults of Induction Motor Using Park’s Vector Approach

    Directory of Open Access Journals (Sweden)

    Ratna Dahiya

    2010-08-01

    Full Text Available The reliability of an induction motor is of paramount importance in industrial, commercial, aerospace and military applications. Bearing play an important role in the reliability and performance of all motor systems. Due to close relationship between motor system development and bearing assembly performance, it is difficult to imagine the progress of modern rotating machinery without consideration of the wide application of bearing. Most faults arising in motors are often linked to bearing faults. This paper presents an experimental study to diagnose the bearing fault with help of Park’s vector approach. The experiment is conducted on 0.5 hp three phaseinduction motor. The bearing faults are replicated in the laboratory by drilling the outer and inner race of ball bearing with help of electric discharge machining. The LabVIEW software is used in the experiment to acquire the signal. The acquired signal is analyzed with Park vector approach. The current Park’s vector presentation is generated by programming in LabVIEW. The practical results show that Park’s Vector approach is an effective technique to diagnose the bearing fault at early stage.

  19. Determination of Contact Time of Rubber Balls Using a Digital Oscilloscope

    Science.gov (United States)

    Wadhwa, Ajay

    2010-01-01

    We present a new method for determining the contact time of a rubber ball with the rebounding surface by using a sound-detecting electronic circuit and a digital storage oscilloscope. The rubber ball (a tennis ball or squash ball) is dropped from a known height onto a rigid surface and its contact time on first bounce is determined on the…

  20. Constraints on self-interacting Q-ball dark matter

    CERN Document Server

    Enqvist, Kari; Multamaki, T P; Vilja, I

    2002-01-01

    We consider different types of Q-balls as self-interacting dark matter. For the Q-balls to act as the dark matter of the universe they should not evaporate, which requires them to carry very large charges; depending on the type, the minimum charge could be as high as Q \\sim 10^{33} or the Q-ball coupling to ordinary matter as small as \\sim 10^{-35}. The cross-section-to-mass ratio needed for self-interacting dark matter implies a mass scale of m \\sim O(1) MeV for the quanta that the Q-balls consist of, which is very difficult to achieve in the MSSM.

  1. Treatment of ASP produced water with hydrophilic fibre ball filtration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The conventional treatment process cannot meet the need for treatment of produced water from alkaline/surfactant/polymer flooding( ASP produced water) in Daqing oilfield. In this study, a new type of hydrophilic fibre ball medium was developed through surface modification method. The hydrophilic property of the surface modified fibre ball was tested with ASP produced liquid at laboratory. The results showed that this fibre ball had higher oil degreasing efficiency. The surface components were also observed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, the result showed that the hydrophilic fibre' s surface was covered by sulfonic group. Using hydrophilic fibre ball as filter medium, a new type of filter was designed to treat ASP produced water in pilot-scale experiments. The obtained results indicated that this type of filter had high capability and efficiency for the treatment of ASP produced water. This filter should have a better application prospect in oilfield produced water treatment.

  2. Ball lightning as a route to fusion energy

    International Nuclear Information System (INIS)

    The reality of ball lightning is attested to by observations reported in surveys of large populations, which are the subject of several books. These observations indicate that its characteristics may be relevant to fusion energy applications. Ball lightning can have a diameter up to several meters, a lifetime of over 100 seconds, an energy content in excess of 10 megajoules, and an energy density and a kinetic pressure greater than that of a reacting DT plasma. This paper reviews some of the properties of ball lightning which commend it to the attention of the fusion community, and it discusses some potential advantages and applications of ball lightning fusion reactors. 11 refs., 6 figs., 1 tab

  3. An experiment on a ball-lightning model

    International Nuclear Information System (INIS)

    We discuss total internal reflection (TIR) from an interface between glass and gainy gaseous media and propose an experiment for strong light amplification related to investigation of a ball-lightning model

  4. An overview of Ball Aerospace cryogen storage and delivery systems

    Science.gov (United States)

    Marquardt, J.; Keller, J.; Mills, G.; Schmidt, J.

    2015-12-01

    Starting on the Gemini program in the 1960s, Beech Aircraft (now Ball Aerospace) has been designing and manufacturing dewars for a variety of cryogens including liquid hydrogen and oxygen. These dewars flew on the Apollo, Skylab and Space Shuttle spacecraft providing fuel cell reactants resulting in over 150 manned spaceflights. Since Space Shuttle, Ball has also built the liquid hydrogen fuel tanks for the Boeing Phantom Eye unmanned aerial vehicle. Returning back to its fuel cell days, Ball has designed, built and tested a volume-constrained liquid hydrogen and oxygen tank system for reactant delivery to fuel cells on unmanned undersea vehicles (UUVs). Herein past history of Ball technology is described. Testing has been completed on the UUV specific design, which will be described.

  5. Evaluation of tensile properties of cast stainless steel using ball

    International Nuclear Information System (INIS)

    In this study the ball indentation tests were performed on the four unaged cast stainless steel and 316 stainless steel, which have different microstructure and strength, to examine the applicability of ball indentation test to the evaluation of thermal aging of cast stainless steel. Also, the reliability of test results were analyzed by evaluating the scattering of data tested from each material and by comparing tensile properties obtained from ball indentation test and tensile test. The results showed that the maximum standard deviation to mean value are less than 6%, and the average standard deviation to mean value are about 1.5∼2.5%, when 2 point data that show out of trend were discarded from the data set tested a single specimen. Also, the scattering increased slightly with decreasing δ-ferrite content. Additionally, the ball indentation test predicted the tensile properties of cast stainless steel within an error of ±10% for all materials

  6. Nano-porous calcium phosphate balls.

    Science.gov (United States)

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. PMID:26052107

  7. Transport in rotary drums and ball mills

    International Nuclear Information System (INIS)

    This report contains investigations into the influence exerted by operating conditions, material properties and geometry of the apparatus and of the discharge plate on the transport behaviour of narrow quartz sand fractions in a model apparatus. The transport coefficients are determined in residence time experiments with Na-24-labelling. The dependence obtained between the transport coefficients and the experimental parameters permits a coherent interpretation if the assumption is made that the two types of transport occur in different phases of radial motion: Convection takes place during ascend while axial dispersion is generated in the falling and ranging process. Furthermore, a model has been developed for evaluating the throughput of rotary drums and ball mills, respectively; it is based on the assumption that the throughput is governed by the material flux through the discharge plate. The efflux takes place only in the ascending zone as a result of gravity and centrifugal forces acting parallel to the discharge plate. A deduced relationship describing the material flow through the discharge apertures in connection with the calculable zone of ascend leads to an expression allowing to determine the mass flow rate as a function of material properties, operating conditions and geometry of the discharge plate. A comparison between experimental and calculated data shows good agreement. (orig.)

  8. Role of Dimples on Golf Ball

    Science.gov (United States)

    Choi, Jin

    2005-11-01

    It is an open question why the drag coefficient on golf ball remains nearly constant with increasing Reynolds number after its sharp decrease. In order to investigate this interesting phenomenon, we measure the drag, separation angle, wall pressure and streamwise velocity inside/outside dimples before main separation. When drag reduction occurs with dimples, the separation angle measured is nearly constant even with increasing Reynolds number. Also, the wall pressure distributions outside dimples are nearly the same at different Reynolds numbers, although those inside dimples vary depending on the Reynolds number. From the streamwise velocity measurement, it is found that dimples located at the angles of 65^o ˜90^o (three rows of dimples exist in our experimental setup) make an important role in changing flow characteristics. Inside one or two rows of dimples located at those angles, a small separation bubble exists and flow becomes quickly transitional and turbulent with reattachment. After the reattachment, the flow does not separate at the downstream dimples owing to fuller velocity profile. With dimples, the main separation occurs further downstream at 110 degree. This main separation angle does not change even with increasing Reynolds number, because downstream dimples do not make an important role in changing flow characteristics any more.

  9. A sharp adaptive confidence ball for self-similar functions

    OpenAIRE

    Nickl, Richard; Szabó, Botond

    2014-01-01

    In the nonparametric Gaussian sequence space model an $\\ell^2$-confidence ball $C_n$ is constructed that adapts to unknown smoothness and Sobolev-norm of the infinite-dimensional parameter to be estimated. The confidence ball has exact and honest asymptotic coverage over appropriately defined `self-similar' parameter spaces. It is shown by information-theoretic methods that this `self-similarity' condition is weakest possible.

  10. The constitution, evaluation and ceramic properties of ball clays

    OpenAIRE

    Wilson Ian Richard

    1998-01-01

    Ball clay is a fine-grained highly plastic, mainly kaolinitic, sedimentary clay, the higher grades of which fire to a white or near white colour. The paper will review the origin of the term "Ball Clay" and the location and origins of several deposits with particular emphasis on the mineralogical, physical and rheological properties which make the clays so important in ceramics bodies. Particular attention will be paid to the well known bay clay deposits of Devon and Dorset in southwest Engla...

  11. Folktales and Other References in Toriyama's Dragon Ball

    OpenAIRE

    Mínguez López, Xavier

    2014-01-01

    The aim of this article is to show the relationship between Japanese folktales and Japanese anime as a genre, especially how the intertextuality with traditional tales and myth subvert its conventional use. To meet this goal, the author examines Toriyama¿s successful Dragon Ball series, which has enjoyed continued popularity right from its first publication in the 1980s. The article analyses the parallelism between Dragon Ball and a classic Chinese novel, Journey to the West, its main source....

  12. Ball Lens Fiber Optic Sensor based Smart Handheld Microsurgical Instrument

    OpenAIRE

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2013-01-01

    During freehand performance of vitreoretinal microsurgery the surgeon must perform precise and stable maneuvers that achieve surgical objectives and avoid surgical risk. Here, we present an improved smart handheld microsurgical tool which is based on a ball lens fiber optic sensor that utilizes common path swept source optical coherence tomography. Improvements include incorporation of a ball lens single mode fiber optic probe that increases the working angle of the tool to greater than 45 de...

  13. ANALYSIS OF CAUSES OF BEARING DAMAGE OF BRIDGE SUPPORT OF STACKER-RECLAIMER ZGOT 15400.120

    Directory of Open Access Journals (Sweden)

    Tadeusz SMOLNICKI

    2014-06-01

    Full Text Available An example of the analysis of a large-size slewing bearing supporting the bridge of the largest in Poland stacker-reclaimer. The turning node was constructed based on the catalogue slewing bearing with four-point contact. The analysis was performed in order to identify the causes of rapid degradation of the bearing. In addition to the macroscopic tests, not described in this article, to verify the correct configuration of the supporting components and to determine the distribution of the loading, the FEM model was build, including the original replacement elements for modelling balls with four-point contact. The measurements of strain of occurred loading were also conducted. Particular attention was paid to the catalogue selection procedures of slewing bearings. The results of no compatibility between algorithms published by various manufacturers of bearings was shown.

  14. Effect of panel shape of soccer ball on its flight characteristics

    OpenAIRE

    Sungchan Hong; Takeshi Asai

    2014-01-01

    Soccer balls are typically constructed from 32 pentagonal and hexagonal panels. Recently, however, newer balls named Cafusa, Teamgeist 2, and Jabulani were respectively produced from 32, 14, and 8 panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball, named Brazuca, was produced from six panels and will be used in the 2014 FIFA World Cup in Brazil. There have, however, been few studies on the aerodynamic properties of balls constructed...

  15. Reliability for fluid bearings design

    OpenAIRE

    DIOP, Khadim; CHARKI, Abdérafi; CHAMPMARTIN, Stéphane; AMBARI, Abdelhak

    2013-01-01

    This paper presents a new methodology for evaluating the failure probability of fluid bearings which are sensitive components for the design of machine rotors, mechatronic systems and high precision metrology. The static and dynamic behavior of a fluid bearing depends on several parameters, such as external load, bearing dimensions, supply pressure, quality of the machined surfaces, fluid properties, etc. In this paper, the characteristics of a simple geometry thrust bearing are calculated an...

  16. Reliability of a hydrostatic bearing

    OpenAIRE

    CHARKI, Abderafi; DIOP, Khadim; CHAMPMARTIN, Stéphane; AMBARI, Abdelhak

    2013-01-01

    This paper presents a methodology for evaluating the failure probability of fluid bearings, which are sensitive components for the design of machine rotors, mechatronic systems, and high precision metrology. The static and dynamic behavior of a fluid bearing depends on several parameters, such as external load, bearing dimensions, supply pressure, quality of the machined surfaces, fluid properties, etc. In this paper, the characteristics of a simple geometry hydrostatic bearing are calculated...

  17. Households' Interest-bearing Assets

    OpenAIRE

    Ellis Connolly; Fiona Fleming; Jarkko Jääskelä

    2012-01-01

    Households invest around two-fifths of their financial assets in interest-bearing assets. These assets are predominantly held directly in deposits and also via superannuation and other investment funds. Deposits have grown strongly in recent years, although there has been no growth in interest-bearing securities. Compared with other advanced economies, interest-bearing assets represent a relatively small share of financial assets. For the household sector as a whole, interest-bearing assets a...

  18. Centrifugally decoupling touchdown bearings

    Science.gov (United States)

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  19. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  20. Rotating plug bearing and seal

    Science.gov (United States)

    Wade, Elman E.

    1977-01-01

    A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

  1. Rotating plug bearing and seal

    International Nuclear Information System (INIS)

    Disclosed is a bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing. 19 claims, 3 figures

  2. ANSWER: A bear paw.

    OpenAIRE

    Ian BICKLE

    2012-01-01

    (Refer to page 186)Answer: Bear Paw sign of Xanthogranulomatous PyelonephritisThe contrast enhanced (portal venous phase)CT of the abdomen showed a global enlargement of the right kidney. There are multiplelow attenuation areas in the renal parenchyma, in a ‘hydronephrotic type manner’, but with no true hydronephrosis. This is due to a renal calculus lying in a contracted pelvis with dilated calyces that contain inflammatory debris. A rim of normal renal tissue enhancesperipherally. The appea...

  3. Theory of operation for the ball rheometer

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, C.L.; Colson, J.B. [Pacific Northwest Lab., Richland, WA (United States); Pasamehmetoglu, K.O.; Unal, C.; Edwards, J.N.; Abbott, J. [Los Alamos National Lab., NM (United States)

    1994-12-01

    The Hanford Site contains over 100 high-volume tanks containing high-level radioactive wastes. The tank which has received the most attention is Tank 101-SY, which is a double shell tank containing a caustic mixed-waste slurry. The ball rheometer developed in this work is intended at least initially for application in this tank. Tank 101-SY is known to periodically release flammable and toxic gases during events known as rollovers. The tank waste is largely made up of two layers, a supernatant liquid layer underneath which is a thick sludge layer. The two layers are called the convective (C) and the nonconvective (NC) regions, so called because of the thermal transport properties ascribed to each. Although they have significant uncertainty, the current theology data suggest the existence of a yield stress in the highly viscous nonconvective layer. Gas generated in the waste can be held in the NC layer if the material yield strength or its viscosity is high enough. Gas cannot be held in the C layer to any appreciable extent unless it is in solution. As gas continues to be generated by chemical or other processes, the number of gas bubbles and/or their sizes increases in the NC layer. A rollover occurs when the amount of gas trapped in the nonconvective region becomes great enough to overcome forces holding it in place. These forces are believed to be dependent on the theology of the nonconvective region and perhaps the bubble surface tension. The buoyancy forces on the bubbles exceed the restraining forces arising from the yield stress and the viscosity of the NC layer. Theology is then seen to be quite important in determining the nature of gas release events in this tank.

  4. Quenching simulation of steel grinding balls

    Directory of Open Access Journals (Sweden)

    Zapata-Hernández, Oscar

    2015-09-01

    Full Text Available The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.Las transformaciones de fase en aceros de alto carbono durante su temple y un posterior periodo de estabilización fueron modelizadas por medio del uso de paquetes computacionales basados en el método del elemento finito y de la transformación cinética de los aceros. El modelo se usó para predecir los cambios de temperatura y microestructura que se presentan en bolas de dos diferentes tamaños empleadas en estaciones de molienda de minerales. Se encontró una buena correlación entre las temperaturas medidas mediante la inserción de termopares y aquellas predichas por el modelo una vez que se modificó la conductividad térmica del acero en el intervalo mixto de fases. La predicción de las transformaciones de fase se confirmó a través del análisis metalográfico.

  5. Anti-backlash gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  6. Vibration response mechanism of faulty outer race rolling element bearings for quantitative analysis

    Science.gov (United States)

    Cui, Lingli; Zhang, Yu; Zhang, Feibin; Zhang, Jianyu; Lee, Seungchul

    2016-03-01

    For the quantitative fault diagnosis of rolling element bearings, a nonlinear vibration model for fault severity assessment of rolling element bearings is established in this study. The outer race defect size parameter is introduced into the dynamic model, and vibration response signals of rolling element bearings under different fault sizes are simulated. The signals are analyzed quantitatively to observe the relationship between vibration responses and fault sizes. The impact points when the ball rolls onto and away from the defect are identified from the vibration response signals. Next, the impact characteristic that reflects the fault severity in rolling element bearings is obtained from the time interval between two impact points. When the width of the bearing fault is small, the signals are presented as clear single impact. The signals gradually become double impacts with increasing size of defects. The vibration signals of a rolling element bearings test rig are measured for different outer race fault sizes. The experimental results agree well with the results from simulations. These results are useful for understanding the vibration response mechanism of rolling element bearings under various degrees of fault severity.

  7. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

  8. 60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications, Report on NASA-Kamatics SAA3-1288

    Science.gov (United States)

    Dellacorte, Christopher; Jefferson, Michael

    2015-01-01

    Under NASA Space Act Agreement (SAA3-1288), NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54 kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

  9. Effect of soccer shoe upper on ball behaviour in curve kicks

    Science.gov (United States)

    Ishii, Hideyuki; Sakurai, Yoshihisa; Maruyama, Takeo

    2014-08-01

    New soccer shoes have been developed by considering various concepts related to kicking, such as curving a soccer ball. However, the effects of shoes on ball behaviour remain unclear. In this study, by using a finite element simulation, we investigated the factors that affect ball behaviour immediately after impact in a curve kick. Five experienced male university soccer players performed one curve kick. We developed a finite element model of the foot and ball and evaluated the validity of the model by comparing the finite element results for the ball behaviour immediately after impact with the experimental results. The launch angle, ball velocity, and ball rotation in the finite element analysis were all in general agreement with the experimental results. Using the validated finite element model, we simulated the ball behaviour. The simulation results indicated that the larger the foot velocity immediately before impact, the larger the ball velocity and ball rotation. Furthermore, the Young's modulus of the shoe upper and the coefficient of friction between the shoe upper and the ball had little effect on the launch angle, ball velocity, and ball rotation. The results of this study suggest that the shoe upper does not significantly influence ball behaviour.

  10. Design and verification test of the small absorber ball system of the HTR-10

    International Nuclear Information System (INIS)

    A small absorber ball system is the second shutdown system of the 10 MW High Temperature Gas-cooled Reactor-Test Module. When the control rod system is out of operation, the small absorber ball system is required to emergency shut down the reactor by means of boron carbide balls totally dropping into channels in the side reflector by gravity. Before the reactor re-operates, these small absorber balls must be conveyed from channels in the side reflector back to the ball storage vessels below the head of reactor pressure vessel by a pneumatic conveying process. Detailed design of the small absorber ball system was carried out, and all the components were manufactured. In order to check the performances of the small absorber ball system, a pneumatic conveying experiment and a hot test were carried out in the laboratory, and also a pre-operation of the small absorber ball system was verified on the reactor site at room temperature. Test data of the small absorber ball system show that all the parameters, including time of ball dropping, time of ball conveying back, indication of ball level in the ball storage vessel, gas flowrate, and valve operation states, are acceptable and reasonable. The small absorber ball system has been shown to be capable of performing satisfactorily at operating temperatures of the reactor

  11. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  12. Studies on ball screw type damper with flyball governor, (1)

    International Nuclear Information System (INIS)

    Mechanical snappers are the aseismatic supports of piping system in high temperature, high humidity or radiation atmosphere, which are composed of ball screws, flywheels and disk brakes. They can follow gradual movement, but restricts the deformation of piping in violent movement such as earthquakes. From the viewpoint of using the supports with ball screws as general vibration preventer rather than constraint, the authors have examined several ball screw type dampers of new types. In this paper, when the damper composed of a ball screw, a flywheel and a pendulum was attached to a vibration system of one degree of freedom, the nonlinear forced vibration and its stability are theoretically discussed, and compared with the results of linear analysis and experiment in the previous study. Also the effect of the damper is explained. In this case, a ball nut was fixed on a primary mass. The equations of motion, the steady solution and its stability, the linear solution, an example of the numerical calculation and the experiment are reported. The good effect of damping was obtained when the ratio of the natural frequency of a governor to a main vibration system was set around 2. (Kako, I.)

  13. New data on the formation of Carboniferous coal balls

    Energy Technology Data Exchange (ETDEWEB)

    Scott, A.C.; Mattey, D.P.; Howard, R. [University of London, Egham (United Kingdom). Royal Holloway and Bedford New College, Dept. of Geology

    1996-10-01

    Coal balls are formed from the precipitation of carbonate minerals, predominantly calcite, from water during or immediately post-peat formation. Previous petrological studies suggest permineralization occurred at various stages during the peatificiation process by precipitation from a mixture of marine and meteoric freshwater. The geochemical studies reported here aimed to test previous theories of coal ball formation. The coal balls studied are from Upper Carboniferous and Carboniferous/Permian coal seams in Britain, United States of America, Belgium and China. Stable carbon isotopic values of calcites range from {delta}{sup 13}C of -5 to -35 parts per thousand indicating highly variable contribution of decayed organic matter to the carbonate cement. Oxygen isotopic values of delta({sup 18}) range from -3 to -15 parts per thousand suggest both marine and meteoric freshwater sources. The range, in the British coal balls in particular, with {delta}{sup 13}C ranging from -7 to -25 parts per thousand indicates the complexity of carbonate generation. Isotopic data support at least four theories of carbonate coal ball formation. This makes their absence from post-Permian coals the more puzzling and it is suggested that the overall structure of the peat may play a role.

  14. Contribution to the physics of high energy ball milling

    International Nuclear Information System (INIS)

    We have characterized the parameters which control the stability of amorphous phases under ball milling on the model alloys (NixZry). We have improved a vibrating frame grinder to perform experiments at several controlled temperatures under static vacuum. Based on analyzing the movement of the milling ball, we have evaluated the frequency of impact (f) and the relative velocity of the ball at the time impact (Vmax) for different vibration amplitudes of the frame. The kinetic of amorphization by ball milling, studied by x-ray diffraction and transmission electron microscopy, shows that: - a fully amorphous phase is obtained provided that the 'specific milling intensity' is larger than a threshold value. The specific milling intensity is defined as the impact momentum times the impact frequency divided by the mass of powder (MbVmaxf/Mp): Mp, Mb are the mass of the ball and the powder). The threshold is composition and temperature dependent; - below the amorphization threshold, a two-phase microstructure (crystalline phase imbedded in an amorphous cement) is stabilized. The alloy achieves a steady state fraction of amorphous phase, which increases with the milling intensity and decreases with increasing the milling temperature. A study of the mechanical alloying of NbTiAl2 starting from elemental powders is also presented. (Author). refs., figs., tabs

  15. Q ball Decay Rates into Gravitinos and Quarks

    CERN Document Server

    Kawasaki, Masahiro

    2012-01-01

    The Affleck-Dine mechanism, which is one of the most attractive candidates for the baryogenesis in supersymmetric theories, often predicts the existence of baryonic Q balls in the early universe. In this scenario, there is a possibility to explain the observed baryon-to-dark matter ratio because Q balls decay into supersymmetric particles as well as into quarks. If the gravitino mass is small compared to the typical interaction energy, the longitudinal component of the gravitino behaves like the massless goldstino. We numerically calculate the goldstino production rates from Q balls in the leading semi-classical approximation without using large radius limit or effective coupling. We also calculate the quark production rates from Q balls in the Yukawa theory with a massive fermion. In deriving the decay rate we also take into account the scalar field configuration of the Q ball. These results are applied to a realistic model in the gauge-mediated supersymmetry breaking and yield the branching ratio of the Q b...

  16. Characterization and Infrared Emission Spectroscopy of Ball Plasmoid Discharges

    Science.gov (United States)

    Dubowsky, Scott E.; McCall, Benjamin J.

    2015-06-01

    Plasmas at atmospheric pressure serve many purposes, from ionization sources for ambient mass spectrometry (AMS) to plasma-assisted wound healing. Of the many naturally occurring ambient plasmas, ball lightning is one of the least understood; there is currently no solid explanation in the literature for the formation and lifetime of natural ball lightning. With the first measurements of naturally occurring ball lightning being reported last year, we have worked to replicate the natural phenomenon in order to elucidate the physical and chemical processes by which the plasma is sustained at ambient conditions. We are able to generate ball-shaped plasmoids (self-sustaining plasmas) that are analogous to natural ball lightning using a high-voltage, high-current, pulsed DC system. Improvements to the discharge electronics used in our laboratory and characterization of the plasmoids that are generated from this system will be described. Infrared emission spectroscopy of these plasmoids reveals emission from water and hydroxyl radical -- fitting methods for these molecular species in the complex experimental spectra will be presented. Rotational temperatures for the stretching and bending modes of H2O along with that of OH will be presented, and the non-equilibrium nature of the plasmoid will be discussed in this context. Cen, J.; Yuan, P,; Xue, S. Phys. Rev. Lett. 2014, 112, 035001. Dubowsky, S.E.; Friday, D.M.; Peters, K.C.; Zhao, Z.; Perry, R.H.; McCall, B.J. Int. J. Mass Spectrom. 2015, 376, 39-45.

  17. Design and Development of Ball Catching Robotic Arm

    Directory of Open Access Journals (Sweden)

    Kartik Sharma

    2012-08-01

    Full Text Available This paper presents a ball catching robotic arm system with 3DOF assembled from the commercially available parts. Other than the previous research work a mechatronically complex system were designed. We have designed a very simple arm which is able to move for catching the ball when it has to move. The given robotic arm system is low cost implementation compare to the previous one. In this system, a single camera system is use to perceive the trajectory of the ball, the system detects the ball in each frame with the help of a fast mean shift algorithm. It calculates the shift of the mean of the identified color intensity and according to that it sends the control commands over the serial port to the robotic arm via ZigBee. The basic objective to catch the flying object at the expected location. This catcher robotic arm can catch the ball thrown to it from 5-6 meter with an average success rate of 70-75%.

  18. Gravitino dark matter from Q-ball decays

    CERN Document Server

    Shoemaker, Ian M

    2009-01-01

    Affleck-Dine baryogenesis, accompanied by the formation and subsequent decay of Q-balls, can generate both the baryon asymmetry of the universe and dark matter in the form of gravitinos. The gravitinos from Q-ball decay dominate over the thermally produced population if the reheat temperature is less than 10^7 GeV. We show that a gravitino with mass around 1 GeV is consistent with all observational bounds and can explain the baryon-to-dark-matter ratio in the gauge-mediated models of supersymmetry breaking for a wide range of cosmological and Q-ball parameters. Moreover, decaying Q-balls can be the dominant production mechanism for m_{3/2} < 1 GeV gravitinos if the Q-balls are formed from a (B-L) = 0 condensate, which produces no net baryon asymmetry. Gravitinos with masses in the range (50 eV - 100 keV) produced in this way can act as warm dark matter and can have observable imprint on the small-scale structure.

  19. Bearings only naval tracking

    Energy Technology Data Exchange (ETDEWEB)

    Barth, M.J.

    1984-11-01

    Two commonly used Extended Kalman Filter tracking algorithms utilize the Relative Cartesian and Modified Polar coordinate systems. This report compares the two algorithms by exercising a destroyer-Submarine (DD/SS) computer simulation. A simple engagement geometry is employed which encompasses the major DD/SS options available. Error statistics are developed by Monte Carlo methods. Results are presented which show that the circular error depends upon the diagonal values of the error covariance matrix. The results also support (but do not establish) that the optimum DD manuevuer is that which minimizes the range while maximizing the bearing rate. 4 refs., 5 figs., 4 tabs.

  20. Self lubricating fluid bearings

    International Nuclear Information System (INIS)

    The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid

  1. Squash ball to eye ball: the likelihood of squash players incurring an eye injury.

    Science.gov (United States)

    Barrell, G V; Cooper, P J; Elkington, A R; Macfadyen, J M; Powell, R G; Tormey, P

    1981-10-01

    The records of the 118 patients treated as Southampton Eye Hospital during 1978-9 for injuries incurred while playing squash, badminton, tennis, table tennis, cricket, and football show that for squash the main cause of eye injury was the player being hit by the ball. Severe eye injuries--those requiring treatment as an inpatient--were rare but much more frequent than such injuries in other sports. Less serious injuries--those requiring treatment as an outpatient--were also rare, with a frequency comparable with that of similar injuries in football and badminton. Squash players are most unlikely to incur an eye injury, but should this occur it has far-reaching consequences both in the short and the long term. Each individual player must weigh these chances and consequences against the possible inconvenience of using some form of eye protection. PMID:6793167

  2. Friction moment analysis of space gyroscope bearing with ribbon cage under ultra-low oscillatory motion

    Directory of Open Access Journals (Sweden)

    Jiang Shaona

    2014-10-01

    Full Text Available This paper presents the model of calculating the total friction moment of space gyroscope ball bearings which usually work under ultra-low oscillatory motion and are very sensitive to the friction moment. The aim is to know the proportion of the friction moment caused by each frictional source in the bearing’s total friction moment, which is helpful to optimize the bearing design to deduce the friction moment. In the model, the cage dynamic equations considering six degree-of-freedom and the balls dynamic equations considering two degree-of-freedom were solved. The good trends with different loads between the measured friction moments and computational results prove that the model under constant rate was validated. The computational results show that when the speed was set at 5 r/min, the bearing’s maximum total friction moment when oscillation occurred was obviously larger than that occurred at a constant rate. At the onset of each oscillatory motion, the proportion of the friction moment caused by cage in the bearing’s total friction moment was very high, and it increased with the increasing speed. The analyses of different cage thicknesses and different clearances between cage pocket and ball show that smaller thickness and clearance were preferred.

  3. Friction moment analysis of space gyroscope bearing with ribbon cage under ultra-low oscillatory motion

    Institute of Scientific and Technical Information of China (English)

    Jiang Shaona; Chen Xiaoyang; Gu Jiaming; Shen Xuejin

    2014-01-01

    This paper presents the model of calculating the total friction moment of space gyro-scope ball bearings which usually work under ultra-low oscillatory motion and are very sensitive to the friction moment. The aim is to know the proportion of the friction moment caused by each frictional source in the bearing’s total friction moment, which is helpful to optimize the bearing design to deduce the friction moment. In the model, the cage dynamic equations considering six degree-of-freedom and the balls dynamic equations considering two degree-of-freedom were solved. The good trends with different loads between the measured friction moments and computational results prove that the model under constant rate was validated. The computational results show that when the speed was set at 5 r/min, the bearing’s maximum total friction moment when oscillation occurred was obviously larger than that occurred at a constant rate. At the onset of each oscillatory motion, the proportion of the friction moment caused by cage in the bearing’s total friction moment was very high, and it increased with the increasing speed. The analyses of different cage thicknesses and different clearances between cage pocket and ball show that smaller thickness and clearance were preferred.

  4. Kicking velocity and effect on match performance when using a smaller, lighter ball in women's football

    DEFF Research Database (Denmark)

    Andersen, Thomas B.; Krustrup, Peter; Bendiksen, Mads;

    2016-01-01

    The present study evaluated the effect of a smaller, lighter ball on kicking speed and technical-tactical and physical match performance in high-level adult female footballers. In the laboratory test setting, the peak ball velocity was 6% higher with the new ball (NB) than the standard ball (SB...... in passing success rate (NB: 68±1% and SB: 68±1%, p>0.05). In conclusion, high-level adult female footballers had a higher kicking speed when using a smaller, lighter ball, but no differences were observed during match-play with the 2 ball types in respect of technical-tactical and physical match...

  5. Superconducting bearings in flywheels

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, T.A.; Campbell, A.M.; Ganney, I.; Lo, W. [Cambridge Univ. (United Kingdom). Interdisciplinary Research Centre in Superconductivity (IRC); Twardowski, T. [International Energy Systems, Chester High Road, Neston, South Wirral (United Kingdom); Dawson, B. [British Nuclear Fuels, Capenhurst, South Wirral (United Kingdom)

    1998-05-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.) 5 refs.

  6. Superconducting bearings in flywheels

    International Nuclear Information System (INIS)

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.)

  7. Design of a high precision falling-ball viscometer

    International Nuclear Information System (INIS)

    The increase in uncertainty throughout the viscosity scale being the principal disadvantage of capillary viscometry, an absolute falling-ball viscometer has been developed, making it possible to cover a wide range of viscosities while keeping a weak uncertainty. The measurement of viscosity of a liquid then rests on the terminal velocity measurement of a falling ball, corrected by the principal identified effects (edge effects, inertial effects, etc.). An experimental bench was developed in order to reach a relative uncertainty of the order of 10-3 to the measure of viscosity. The bench, by the use of a linear camera, allows us to observe the trajectory and to obtain the variations in velocity of the ball inside a cylindrical tube filled with liquid whose viscosity is to be measured

  8. Realtime Vision-Based Surface Defect Inspection of Steel Balls

    Institute of Scientific and Technical Information of China (English)

    Wang Zhong; Xing Qian; Fu Luhua; Sun Hong

    2015-01-01

    In the proposed system for online inspection of steel balls, a diffuse illumination is developed to enhance defect appearances and produce high quality images. To fully view the entire sphere, a novel unfolding method is put forward based on geometrical analysis, which only requires one-dimensional movement of the balls and a pair of cam-eras to capture images from different directions. Moreover, a realtime inspection algorithm is customized to improve both accuracy and efficiency. The precision and recall of the sample set were 87.7% and 98%, respectively. The aver-age time cost on image processing and analysis for a steel ballwas 47 ms, and the total time cost was less than 200 ms plus the cost of image acquisition and balls’ movement. The system can sort 18 000 balls per hour with a spatial reso-lution higher than 0.01 mm.

  9. The Heads and Tails of Buoyant Autocatalytic Balls

    CERN Document Server

    Rogers, Michael C

    2012-01-01

    Buoyancy produced by autocatalytic reaction fronts can produce fluid flows that advect the front position, giving rise to interesting feedback between chemical and hydrodynamic effects. In a large diameter, extended cylinder that is relatively free of boundary constraints, localized initiation of an iodate-arsenous acid (IAA) reaction front on the bottom boundary generates a rising autocatalytic plume. Such plumes have several differences from their non-reactive counterparts. Using numerical simulation, we have found that if reaction is initiated using a spherical ball of product solution well above the bottom boundary, the subsequent flow can evolve much like an autocatalytic plume: the ball develops a reacting head and tail that is akin to the head and conduit of an autocatalytic plume, except that the tail is disconnected from the boundary. In the limit of large initial autocatalytic balls, however, growth of a reacting tail is suppressed and the resemblance to plumes disappears. Conversely, very small bal...

  10. Propagating $q$-field and $q$-ball solution

    CERN Document Server

    Klinkhamer, F R

    2016-01-01

    One possible solution of the cosmological constant problem involves a so-called $q$-field, which self-adjusts so as to give a vanishing gravitating vacuum energy density (cosmological constant) in equilibrium. We show that this $q$-field can manifest itself in other ways. Specifically, we establish a propagating mode ($q$-wave) in the nontrivial vacuum and find a particular soliton-type solution in flat spacetime, which we call a $q$-ball by analogy with the well-known $Q$-ball solution. Both $q$-waves and $q$-balls are expected to play a role for the equilibration of the $q$-field in the very early universe.

  11. Supermassive dark-matter Q-balls in galactic centers?

    CERN Document Server

    Troitsky, Sergey

    2015-01-01

    Though widely accepted, it is not proven that supermassive compact objects (SMCOs) residing in galactic centers are black holes. In particular, the Milky Way's SMCO can be a giant nontopological soliton, Q-ball, made of a scalar field: this fits perfectly all observational data. Similar but tiny Q-balls produced in the early Universe may constitute, partly or fully, the dark matter. This picture explains in a natural way, why our SMCO has very low accretion rate and why the observed angular size of the corresponding radio source is much smaller than expected. Interactions between dark-matter Q-balls may explain how SMCOs were seeded in galaxies and resolve well-known problems of standard (non-interacting) dark matter.

  12. Modeling golf ball fluid mechanics - challenges and opportunities

    Science.gov (United States)

    Squires, Kyle

    2009-11-01

    Numerical simulation presents a powerful tool for understanding the fundamental fluid mechanics that influence golf ball aerodynamics, as well as providing an approach for ultimately analyzing and designing golf balls for manufacture. Robust and accurate simulation strategies are central to providing a means to screen designs prior to costly prototyping and field measurement. Results from a hierarchy of simulation strategies applied to the flow around golf balls will be presented, ranging from Reynolds-averaged Navier-Stokes (RANS) computations to Direct Numerical Simulation (DNS). RANS methods, while leading to computationally efficient approaches, are challenged to represent using ad hoc turbulence models the subtle effects induced by surface dimpling. DNS on the other hand, offers a first-principles approach that enables detailed examination of mechanisms though carries a significant computational cost. Predictions from both techniques are contrasted; opportunities for advancing each technique are identified.

  13. Hurricane Balls: A rigid-body-motion student project

    Science.gov (United States)

    Jackson, David; Mertens, David; Pearson, Brett

    Hurricane Balls is a spinning-top toy that consists of two metal spheres that are welded (or glued) together. The motion of Hurricane Balls provides a beautiful example of rotational motion in which the angular velocity and angular momentum point in different directions. Because the motion is both captivating to students and extremely reproducible, this system is an ideal example to include in a classical mechanics course. Moreover, the excellent agreement between theory and experiment makes a detailed analysis of Hurricane Balls a perfect topic for an independent student project. This talk will give an overview of the system and will provide some tips on how to make such a project a successful student experience.

  14. Biodistribution of nanoparticles of hydrophobic gadopentetic-acid derivative prepared with a planetary ball mill for neutron-capture therapy of cancer

    International Nuclear Information System (INIS)

    Nanoparticles of hydrophobic gadopentetic-acid derivatives (Gd-nanoGR) were prepared with a wet ball-milling process for gadolinium neutron-capture therapy. Ball-milling of solid mass of gadopentetic acid distearylamide with soybean lecithin as a dispersant in the presence of water and subsequent sonication at 70degC resulted in the Gd-nanoGR with the particle size of 63 nm. Biodistribution study using melanoma-bearing hamsters demonstrated that the i.v. injection of the Gd-nanoGR made a higher gadolinium accumulation in tumor (109 μg Gd/g wet tumor at 6h after administration), when compared with the gadolinium-loaded micellar-like nanoparticles previously reported. (author)

  15. A self-similar magnetohydrodynamic model for ball lightnings

    International Nuclear Information System (INIS)

    Ball lightning is modeled by magnetohydrodynamic (MHD) equations in two-dimensional spherical geometry with azimuthal symmetry. Dynamic evolutions in the radial direction are described by the self-similar evolution function y(t). The plasma pressure, mass density, and magnetic fields are solved in terms of the radial label η. This model gives spherical MHD plasmoids with axisymmetric force-free magnetic field, and spherically symmetric plasma pressure and mass density, which self-consistently determine the polytropic index γ. The spatially oscillating nature of the radial and meridional field structures indicate embedded regions of closed field lines. These regions are named secondary plasmoids, whereas the overall self-similar spherical structure is named the primary plasmoid. According to this model, the time evolution function allows the primary plasmoid expand outward in two modes. The corresponding ejection of the embedded secondary plasmoids results in ball lightning offering an answer as how they come into being. The first is an accelerated expanding mode. This mode appears to fit plasmoids ejected from thundercloud tops with acceleration to ionosphere seen in high altitude atmospheric observations of sprites and blue jets. It also appears to account for midair high-speed ball lightning overtaking airplanes, and ground level high-speed energetic ball lightning. The second is a decelerated expanding mode, and it appears to be compatible to slowly moving ball lightning seen near ground level. The inverse of this second mode corresponds to an accelerated inward collapse, which could bring ball lightning to an end sometimes with a cracking sound

  16. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  17. Proposal of a dual-ball atomic fountain clock

    Institute of Scientific and Technical Information of China (English)

    Chunyan Shi; Rong Wei; Zichao Zhou; Tang Li; Yuzhu Wang

    2011-01-01

    @@ A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time, which works like "two fountains", but is more compact since most components of the "two fountains"are shared.It is expected to improve the stability of the fountain markedly.%A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time, which works like “two fountains”, but is more compact since most components of the “two fountains”are shared. It is expected to improve the stability of the fountain markedly.

  18. Electrostatic repulsion of charged pith balls hanging from strings

    International Nuclear Information System (INIS)

    Two positively charged pith balls hang from a nail at the end of equal-length strings in Earth's surface gravitational field. The problem consists in finding each of the hanging angles when the balls do not necessarily have the same mass or charge. The solution is an excellent exercise in developing two skills: wisely choosing the coordinate axes in a free-body diagram, and correctly interpreting the roots and limits of a numerical solution. The treatment is accessible to undergraduate physics majors in their first or second year of physics courses.

  19. Effect of wet grinding on structural properties of ball clay

    International Nuclear Information System (INIS)

    In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature

  20. Quality Improvement in the Production Process of Grinding Balls.

    OpenAIRE

    Andrew Muzinda; Rumbidzai Muvunzi; Catherine Maware

    2013-01-01

    The paper outlines how experiments were carried out to determine the optimum chromium/carbon (Cr/C) ratio that brings the required hardness of 65HRC and to establish a quenching technique for the grinding balls. Matlab was also used to develop a mathematical model for the ball wear rate and its cost effectiveness basing on surface theory and volume theory. From the experimental results, the Cr/C ratio in the chemical composition 18:2 gave the required hardness. Also water quenched grinding ba...

  1. Volumes of unit balls of mixed sequence spaces

    OpenAIRE

    Kempka, Henning; Vybíral, Jan

    2015-01-01

    The volume of the unit ball of the Lebesgue sequence space $\\ell_p^m$ is very well known since the times of Dirichlet. We calculate the volume of the unit ball in the mixed norm $\\ell^n_q(\\ell_p^m)$, whose special cases are nowadays popular in machine learning under the name of group lasso. We consider the real as well as the complex case. The result is given by a closed formula involving the gamma function, only slightly more complicated than the one of Dirichlet. We close by an overview of ...

  2. A power recirculating test rig for ball screw endurance tests

    Directory of Open Access Journals (Sweden)

    Giberti Hermes

    2016-01-01

    Full Text Available A conceptual design of an innovative test rig for endurance tests of ball screws is presented in this paper. The test rig layout is based on the power recirculating principle and it also allows to overtake the main critical issues of the ball screw endurance tests. Among these there are the high power required to make the test, the lengthy duration of the same and the high loads between the screw and the frame that holds it. The article describes the test rig designed scheme, the kinematic expedients to be adopted in order to obtain the required performance and functionality and the sizing procedure to choose the actuation system.

  3. Ball milling of chalcopyrite: Moessbauer spectroscopy and XRD studies

    International Nuclear Information System (INIS)

    The aim of this project is to study the behavior of chalcopyrite under ball milling for extended periods in order to determine how it's decompose or transform. Tests were done with chalcopyrite mixed with iron and zinc with and without surfactant. The use of surfactants has various effects such as avoiding oxidation and clustering of the fine particles. In all case magnetic chalcopyrite is transformed into a paramagnetic component showing a disordered structure, thus revealing that Cu atoms have replaced Fe atoms. In the case of ball milling in air, chalcopyrite is decomposed with the lost of iron, while in milling under surfactants, iron enters into the chalcopyrite structure. (author)

  4. Note: A 1-m Foucault pendulum rolling on a ball

    Science.gov (United States)

    Salva, H. R.; Benavides, R. E.; Venturino, J. A.; Cuscueta, D. J.; Ghilarducci, A. A.

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  5. Energy Landscape of d-Dimensional Q-balls

    CERN Document Server

    Gleiser, M; Gleiser, Marcelo; Thorarinson, Joel

    2005-01-01

    We investigate the properties of Q-balls in d spatial dimensions. First, a generalized virial relation for these objects is obtained, followed by variational estimates for their energies for arbitrary charge Q. These analytical estimates are then contrasted with numerical results and their accuracy evaluated. Based on the results, we offer a simple criterion to classify ``large'' and ``small'' d-dimensional Q-balls. A minimum charge is computed and its dependence on spatial dimensionality is shown to scale as \\Q_{\\rm min} \\sim \\exp(d). We also briefly investigate the existence of Q-clouds in d dimensions.

  6. Charge, mass and energy measured in the Plastic Ball

    International Nuclear Information System (INIS)

    In relativistic nuclear collisions the multiplicity of charged particles reflects the violence of the reaction and, presumably, the impact parameter. Furthermore, the total transverse energy in a collision might be a signature of compression. Both quantities are global features that can be measured in the Plastic Ball. The total mass in an event in light charge fragments can be detected (with assumptions made in certain kinematic regions) through particle identification. In addition, the neutron detection efficiency is quite high because of the large thickness of the plastic scintillator in the Plastic Ball. Here the authors present several global quantities for the reaction of 400 MeV/nucleon Nb + Nb

  7. Evidence of microscopic ball lightning in cold fusion experiments

    International Nuclear Information System (INIS)

    There is evidence of microscopic ball lightning in several methods of cold fusion and transmutation. Thus far the experiments of Matsumoto, Miley, Shoulders, Savvatimova, and Urutskoev et al. have shown evidence of these objects that range in size from sub-atomic to about 1 mm in diameter. This article presents pictures and evidence collected by these groups, summarizes the evidence found by other groups, and discusses the significance of microscopic ball lightning. The implications for atomic physics and physics in general are discussed. (author)

  8. Boric Acid Levels in Fresh Noodles and Fish Ball

    OpenAIRE

    Pang-Hung Yiu; Jian See; Amartalingam Rajan; Choon-Fah J. Bong

    2008-01-01

    Boric acid (H3BO3) is detrimental to human health if consumed in excess. However, it continues to be used in the production of food especially noodles and some processed seafood such as fish ball. Five kinds of noodles and a type of fish ball were collected over a period of four weeks from a random sample of manufacturers in Bintulu, Sarawak, Malaysia. The boric acid in these food samples were analyzed by the curcumin-acetic acid method using 2-ethyl-1, 3-hexanediol (EHD) extraction. Results ...

  9. Comparison of exit time moment spectra for extrinsic metric balls

    DEFF Research Database (Denmark)

    Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente

    We prove explicit upper and lower bounds for the $L^1$-moment spectra for the Brownian motion exit time from extrinsic metric balls of submanifolds $P^m$ in ambient Riemannian spaces $N^{n}$. We assume that $P$ and $N$ both have controlled radial curvatures (mean curvature and sectional curvature......, respectively) as viewed from a pole in $N$. The bounds for the exit moment spectra are given in terms of the corresponding spectra for geodesic metric balls in suitably warped product model spaces. The bounds are sharp in the sense that equalities are obtained in characteristic cases. As a corollary we also...

  10. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  11. Investigation of briquetting of metal waste from the bearing industry.

    Science.gov (United States)

    Borowski, Gabriel; Kuczmaszewski, Jozef

    2005-10-01

    An economical method to process the metal waste that comes from the ball-bearing industry is presented. The purpose of the study was to determine the physical-chemical properties of the material, to present the most suitable binders and identify the factors that can affect briquette strength. The mechanical strength and resistance to gravitational drop were defined for both fresh briquettes and those that had been seasoned. The briquette structure was also tested. On the basis of the results of experimental studies and laboratory trials two techniques for processing the waste from the ballbearing industry on an industrial technological scale were developed. The economic and ecological impacts of these industrial applications were examined. The results of the investigations suggest that the briquettes might be recycled in steel-making furnaces. The reported solution to the problem of management of this type of waste appears to be universal and could also be applied by other waste-related enterprises. PMID:16273956

  12. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  13. Fish of Bear Lake, Utah

    OpenAIRE

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    There are 13 species of fish found in the waters of Bear Lake. Of those 13, 4 are endemic (found only in Bear Lake). The 4 endemics species are Bonneville cisco, Bonneville whitefish, Bear Lake whitefish, and Bear Lake sculpin. Five of the remaining 9 fish species are native to the region, and 4 are exotic introductions. These native fishes are the Bonneville cutthroat trout, Utah sucker, redside shiner, speckled dace and Utah chub. The exotic fishes are lake trout, common carp, yellow p...

  14. Dynamic Analysis of Engine Bearings

    Directory of Open Access Journals (Sweden)

    H. Hirani

    1999-01-01

    Full Text Available This paper presents a simple methodology to evaluate the stiffness and damping coefficients of an engine bearing over a load cycle. A rapid technique is used to determine the shaft ‘limit cycle’ under engine dynamic loads. The proposed theoretical model is based on short and long bearing approximations. The results obtained by present approximation are compared with those obtained by numerical method. The influence of thermal effects on the stiffness and damping coefficients is predicted by using a simplified thermal analysis. In order to illustrate the application of the proposed scheme, one engine main bearing and a connecting rod bearing are analysed.

  15. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace

    Science.gov (United States)

    Dellacorte, Christopher

    2014-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded contact points (e.g., meshing gear teeth, bearing balls-raceway contacts) experience high contact stresses. The combination of high hardness and high elastic modulus often leads to damaging contact stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element bearing applications. Bearings and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well

  16. Numerical analysis of hydrogen-assisted rolling-contact fatigue of wind turbine bearings

    Directory of Open Access Journals (Sweden)

    J. Toribio

    2014-10-01

    Full Text Available Offshore wind parks at locations further from the shore often involve serious difficulties, e.g. the maintenance. The bearings of offshore wind turbines are prone to suffer hydrogen-assisted rolling-contact fatigue (HA-RCF. Three important aspects linked with bearing failures are being extensively researched: (i rolling contact fatigue (RCF, (ii influence of carbide particles on fatigue life, and (iii local microplastic strain accumulation via ratcheting. However, there is no reference related to bearing failure in harsh environment. This way, this paper helps to gain a better understanding of the influence of hydrogen on the service life of offshore wind turbine bearings through a numerical study. So, the widely used RCF ball-on-rod test was simulated by finite element method in order to obtain the stress-strain state inside the bearings during life in service and, from this, to elucidate the potential places where the hydrogen could be more harmful and, therefore, where the bearing material should be improved.

  17. Effect of panel shape of soccer ball on its flight characteristics

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2014-05-01

    Soccer balls are typically constructed from 32 pentagonal and hexagonal panels. Recently, however, newer balls named Cafusa, Teamgeist 2, and Jabulani were respectively produced from 32, 14, and 8 panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball, named Brazuca, was produced from six panels and will be used in the 2014 FIFA World Cup in Brazil. There have, however, been few studies on the aerodynamic properties of balls constructed from different numbers and shapes of panels. Hence, we used wind tunnel tests and a kick-robot to examine the relationship between the panel shape and orientation of modern soccer balls and their aerodynamic and flight characteristics. We observed a correlation between the wind tunnel test results and the actual ball trajectories, and also clarified how the panel characteristics affected the flight of the ball, which enabled prediction of the trajectory.

  18. THE EFFECT OF GAMES AND TRAINING PROGRAMS OFFERED AT BALL SCHOOL (BALSCHULE, ON BALL-COORDINATION AMONG FIRST AND SECOND GRADE STUDENTS

    Directory of Open Access Journals (Sweden)

    Behrooz Ebrahimi

    2013-06-01

    Full Text Available The aim of this study is to investigate the effect of games and training programs offered at the Ball school (Ballschule Heidelberg, on ball-coordination among first and second grade students. For this purpose, 38 students from 13 schools covered by the Ball school (Heidelberg Balschule, were chosen as the experimental group (non-random ; in the meantime the consent of the students’ parents were also received. Forty students as well as a control group (non-random of eight normal schools were selected with parental consents. Then through using ball-coordination tests [BKT (BallKoordinationstests. Ball Coordination’s Tests], the level of the ball skills among both groups were measured in the pre-test and Post-test. Tests included kicking ball against the wall (under five conditions. The research methods were semi-experimental with experimental and control groups. Independent variables were also applied to the experimental group and the means and standard deviations were calculated through descriptive statistics. And then, a T-test for statistical analysis of data in related groups were applied. The results showed a significant effect of games and training programs offered at the school ball in the ball-coordination of subjects.

  19. Experimental signatures of supersymmetric dark-matter Q-balls

    OpenAIRE

    Kusenko, Alexander; Kuzmin, Vadim; Shaposhnikov, Mikhail E.; Tinyakov, P. G.

    1997-01-01

    Theories with low-energy supersymmetry predict the existence of stable non-topological solitons, Q-balls, that can contribute to dark matter. We discuss the experimental signatures, methods of detection, and the present limits on such dark matter candidates.

  20. Predicting brain acceleration during heading of soccer ball

    Science.gov (United States)

    Taha, Zahari; Hasnun Arif Hassan, Mohd; Azri Aris, Mohd; Anuar, Zulfika

    2013-12-01

    There has been a long debate whether purposeful heading could cause harm to the brain. Studies have shown that repetitive heading could lead to degeneration of brain cells, which is similarly found in patients with mild traumatic brain injury. A two-degree of freedom linear mathematical model was developed to study the impact of soccer ball to the brain during ball-to-head impact in soccer. From the model, the acceleration of the brain upon impact can be obtained. The model is a mass-spring-damper system, in which the skull is modelled as a mass and the neck is modelled as a spring-damper system. The brain is a mass with suspension characteristics that are also defined by a spring and a damper. The model was validated by experiment, in which a ball was dropped from different heights onto an instrumented dummy skull. The validation shows that the results obtained from the model are in a good agreement with the brain acceleration measured from the experiment. This findings show that a simple linear mathematical model can be useful in giving a preliminary insight on what human brain endures during a ball-to-head impact.

  1. Nocardia asteroids causing pulmonary nocardiosis presenting as fungal ball

    Directory of Open Access Journals (Sweden)

    Bimoch Projna Paty

    2014-01-01

    Full Text Available Pulmonary nocardiosis presenting as a fungal ball in a preexisting cavity is a rare presentation. We report such a case in a 18 yrs old male patient presented with cough with expectoration & episodes of haemoptysis with a past history of tuberculosis. Diagnosis was done by microscopic examination of the resected sample & confirmed on culture.

  2. Application of the Blobo bluetooth ball in wrist rehabilitation training.

    Science.gov (United States)

    Hsieh, Wei-Min; Hwang, Yuh-Shyan; Chen, Shih-Ching; Tan, Sun-Yen; Chen, Chih-Chen; Chen, Yu-Luen

    2016-01-01

    [Purpose] The introduction of emerging technologies such as the wireless Blobo bluetooth ball with multimedia features can enhance wrist physical therapy training, making it more fun and enhancing its effects. [Methods] Wrist injuries caused by fatigue at work, improper exercise, and other conditions are very common. Therefore, the reconstruction of wrist joint function is an important issue. The efficacy of a newly developed integrated wrist joint rehabilitation game using a Blobo bluetooth ball with C# software installed was tested in wrist rehabilitation (Flexion, Extension, Ulnar Deviation, Radial Deviation). [Results] Eight subjects with normal wrist function participated in a test of the system's stability and repeatability. After performing the Blobo bluetooth ball wrist physical therapy training, eight patients with wrist dysfunction experienced approximately 10° improvements in range of motion (ROM) of flexion extension, and ulnar deviation and about 6° ROM improvement in radial deviation. The subjects showed progress in important indicators of wrist function. [Conclusion] This study used the Blobo bluetooth ball in wrist physical therapy training and the preliminary results were encouraging. In the future, more diverse wrist or limb rehabilitation games should be developed to meet the needs of physical therapy training. PMID:26957723

  3. LINEAR SINGULAR INTEGRAL EQUATION ON DOMAINS COMPOSED BY BALLS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    For domains composed by balls in Cn, this paper studies the boundary behaviour of Cauchy type integrals with discrete holomorphic kernels and the corresponding linear singular integral equation on each piece of smooth lower dimensional edges on the boundary of the domain.

  4. Weighted Composition Operators between Hardy Spaces on the Unit Ball

    Institute of Scientific and Technical Information of China (English)

    XUHui-ming; LIUTai-shun

    2004-01-01

    We consider the weighted composition operators between Hardy spaces on the unit ball, and obtain some sufficient and necessary conditions of bounded or compact weighted composition operators. We also prove that the operator from H1 to H1 is compact if and only if it is weakly compact. Meanwhile, we get the analogue on the Bergman spaces.

  5. Reduced graphene oxide synthesis by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, O. [Department of Physics, M.U.C Women' s College, Burdwan 713104 (India); Mitra, S. [MLS Prof' s Unit, Indian Association for the Cultivation of Science, Kolkata 700032 (India); Pal, M. [CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India); Datta, A. [University School of Basic and Applied Science (USBAS), Guru Gobind Singh Indraprastha University, New Delhi 110075 (India); Dhara, S. [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Chakravorty, D., E-mail: mlsdc@iacs.res.in [MLS Prof' s Unit, Indian Association for the Cultivation of Science, Kolkata 700032 (India)

    2015-07-01

    Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. The process of ball milling introduces defects and removes oxygen functional groups, thereby creating the possibility of fine tuning the band gap of all intermediate stages of the structural evolution. A limit of the backbone sp{sup 2} network structure has been found which should be able to accommodate defects, before amorphization sets in. The amorphization of graphene oxide is achieved rather quickly in comparison to that of graphite. From thermogravimetric and differential scanning calorimetric analysis along with Fourier transform infrared (FTIR) and Raman spectroscopic studies, it is found that the number of oxygen-containing groups decreases at a faster rate than that of aromatic double bonds with increasing ball milling time with a maximum limit of 3 h. Several characterization techniques (FTIR, Raman, UV–Visible and X-ray photoelectron spectroscopy) have confirmed that the material synthesized is, indeed, reduced graphene oxide. - Highlights: • Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. • Fine tuning the band gap by introducing defects and removing oxygen functional groups. • Introduction of excess defects leads to amorphization. • Photoluminescence has been observed in the UV-blue region.

  6. The spin relaxation process in the magnetic balls system

    International Nuclear Information System (INIS)

    In this work the spin-spin and spin-lattice relaxation processes for the nuclear spin I in the presence of dipole interaction with magnetic balls with spin S are considered. The relaxation time has been calculated by means of computerized simulations

  7. Reduced graphene oxide synthesis by high energy ball milling

    International Nuclear Information System (INIS)

    Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. The process of ball milling introduces defects and removes oxygen functional groups, thereby creating the possibility of fine tuning the band gap of all intermediate stages of the structural evolution. A limit of the backbone sp2 network structure has been found which should be able to accommodate defects, before amorphization sets in. The amorphization of graphene oxide is achieved rather quickly in comparison to that of graphite. From thermogravimetric and differential scanning calorimetric analysis along with Fourier transform infrared (FTIR) and Raman spectroscopic studies, it is found that the number of oxygen-containing groups decreases at a faster rate than that of aromatic double bonds with increasing ball milling time with a maximum limit of 3 h. Several characterization techniques (FTIR, Raman, UV–Visible and X-ray photoelectron spectroscopy) have confirmed that the material synthesized is, indeed, reduced graphene oxide. - Highlights: • Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. • Fine tuning the band gap by introducing defects and removing oxygen functional groups. • Introduction of excess defects leads to amorphization. • Photoluminescence has been observed in the UV-blue region

  8. Comparison of exit time moment spectra for extrinsic metric balls

    DEFF Research Database (Denmark)

    Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente

    2012-01-01

    We prove explicit upper and lower bounds for the $L^1$-moment spectra for the Brownian motion exit time from extrinsic metric balls of submanifolds $P^m$ in ambient Riemannian spaces $N^n$. We assume that $P$ and $N$ both have controlled radial curvatures (mean curvature and sectional curvature, ...

  9. Generalized isoperimetric inequalities for extrinsic balls in minimal submanifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2002-01-01

    The volume of an extrinsic ball in a minimal submanifold has a well defined lower bound when the ambient manifold has an upper bound on its sectional curvatures, see e.g. [2] and [10]. When this upper bound is non-positive, the second named author has shown an isoperimetric inequality for such do...

  10. These Kids Are Really on the Ball! Invention Competition Winners

    Science.gov (United States)

    Tech Directions, 2008

    2008-01-01

    Judge Harry T. Roman, an electrical engineer and inventor himself, has selected the best entries in the 2007-2008 "Tech Directions" Inventors Award Competition. This year's challenge called for students to devise new uses for the common Ping-Pong ball. Of the results, the judge notes "The ideas submitted were most interesting, with a high number…

  11. Ball lens reflections by direct solution of Maxwell's equations

    International Nuclear Information System (INIS)

    We calculate ball lens reflections, using the exact solution of Maxwell's equations for the scattering of a beam from a dielectric sphere. Our results are consistent to within 1 dB with measurements of backreflection to a single-mode fiber. We also calculate backreflection to an astigmatic spot laser diode. copyright 1995 Optical Society of America

  12. Development of Microcontroller-Based Ball and Beam Trainer Kit

    Directory of Open Access Journals (Sweden)

    Gunawan Dewantoro

    2015-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE A ball and beam trainer kit based on microcontroller was developed for teaching control system course for the sophomore students. This specially-purposed kit consists of a ball located on a beam with a fixed axle at one of its end. At the other end, a servomotor was employed to control the position of the ball by adjusting the rotation angle of the servomotor. Seven predetermined positions were set to 10, 20, 30, 40, 50, 60, and 70 cm relative to the fixed axle of the beam. The Proportional-Integral-Derivative (PID scheme was then used to compensate the error. This kit is equipped with a user interface to configure controller coefficients, select the set points, plot the actual ball position, and display parameter values. The user interface program runs on PC or notebook connected to microcontroller via serial communications. A questionnaire-based assessment about the use of this kit was conducted by 17 students taking the course, giving a rating value of 94.12%.

  13. Whitey SCHe Ball Valves Provide Test Port Isolation

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-15

    These valves are 1/4 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

  14. Thump, ring: the sound of a bouncing ball

    CERN Document Server

    Katz, J I

    2008-01-01

    A basketball bounced on a stiff surface produces a characteristic loud thump, followed by high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms.

  15. Thump, ring: the sound of a bouncing ball

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J I, E-mail: katz@wuphys.wustl.ed [Department of Physics and McDonnell Center for the Space Sciences, Washington University, St Louis, MO 63130 (United States)

    2010-07-15

    A basketball bounced on a stiff surface produces a characteristic loud thump, followed by a high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms.

  16. Precession of a Spinning Ball Rolling down an Inclined Plane

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle a to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, µ, must be at least tan a. The situation is similar for the case of a ball rolling down an inclined plane. In order…

  17. On the Quaternion Ball and the Quaternion Projective Space

    Institute of Scientific and Technical Information of China (English)

    Qi Keng LU

    2005-01-01

    Since the quaternion ball was used to study the AdS/CFT problems for spinor fields, it is worthwhile to study further the geometry (in sense of Klein) and analysis on it and on its extended space (in the sense of Behnke-Thullen), the quaternion projective space.

  18. Female football players don't have balls

    OpenAIRE

    Lippe, Gerd von der

    2008-01-01

    You need balls to play football. So it is obvious that being a girl just won't do as far as the guys are concerned, says Gerd von der Lippe in a devastating critique of the state of affairs in the reporting and support of women's football in Norway.

  19. From the Lab Bench: The invisible crystal ball

    Science.gov (United States)

    A column was written that pondered that advantages of a livestock producer having a crystal ball in their head that could tell you weather patterns, cattle markets, calf crops, etc. You would have such an advantage that there is no reason for your farming operation to fail. The column went through...

  20. Molecular Similarity Based on Super-Ball Algorithm

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The molecular similarity of 139 organic compounds was calculated by the topologic index method, the flexible super-ball algorithm was used to scan similar molecules and structures. The results show that the properties of organic compounds estimated from this method are reliable.