WorldWideScience

Sample records for ball bearings

  1. High-Performance Ball Bearing

    Science.gov (United States)

    Bursey, Roger W., Jr.; Haluck, David A.; Olinger, John B.; Owen, Samuel S.; Poole, William E.

    1995-01-01

    High-performance bearing features strong, lightweight, self-lubricating cage with self-lubricating liners in ball apertures. Designed to operate at high speed (tens of thousands of revolutions per minute) in cryogenic environment like liquid-oxygen or liquid-hydrogen turbopump. Includes inner race, outer race, and cage keeping bearing balls equally spaced.

  2. The correct "ball bearings" data.

    Science.gov (United States)

    Caroni, C

    2002-12-01

    The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

  3. 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

  4. Silicon Nitride Balls For Cryogenic Bearings

    Science.gov (United States)

    Butner, Myles F.; Ng, Lillian W.

    1990-01-01

    Resistance to wear greater than that of 440C steel. Experiments show lives of ball bearings immersed in liquid nitrogen or liquid oxygen increased significantly when 440C steel balls (running on 440C steel races) replaced by balls of silicon nitride. Developed for use at high temperatures, where lubrication poor or nonexistent. Best wear life of any bearing tested to date and ball material spalls without fracturing. Plans for future tests call for use of liquid oxygen as working fluid.

  5. 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

  6. 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.

  7. 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.

  8. Frictional torque numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.

    1982-01-01

    Plastic bearing material wears in ball cup and journal bearings. Contact areas in the ball cup and the journal bearing increase. The frictional torque needed to rotate the ball or journal also increases. When the coefficient of friction is assumed to be constant during wearing out, the frictional t

  9. Frictional torque numbers for ball cup and journal bearings

    OpenAIRE

    Ligterink, D.J.

    1982-01-01

    Plastic bearing material wears in ball cup and journal bearings. Contact areas in the ball cup and the journal bearing increase. The frictional torque needed to rotate the ball or journal also increases. When the coefficient of friction is assumed to be constant during wearing out, the frictional torque increases to a maximum of 1.273 times the frictional torque at zero wear.

  10. 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.

  11. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in millim

  12. Wear numbers for ball cup and journal bearings

    OpenAIRE

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in millimetres, the wear modulus in newtons per square millimetre, the maximum wear depth rate of the cup or the cylindrical bearing in millimetres per second, the force between the mating surfaces in newto...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. 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...

  3. 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.

  4. 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...

  5. 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)...

  6. 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

  7. 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.

  8. 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....

  9. 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...

  10. 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

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. Evaluation of outer race tilt and lubrication on ball wear and SSME bearing life reductions

    Science.gov (United States)

    Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.

    1983-01-01

    Several aspects of the SSME bearing operation were evaluated. The possibility of elastohydrodynamics (EHD) lubrication with a cryogenic fluid was analyzed. Films as thick as .61 microns were predicted with one theory which may be thick enough to provide hydrodynamic support. The film formation, however, is heavily dependent on good surface finish and a low bulk bearing temperature. Bearing dynamics to determine if the radial stiffness of a bearing which are dependent on bearing misalignment were analyzed. Four ball tests were conducted at several environmental conditions from an LN2 bath to 426 C in air. Surface coatings and ball materials are evaluated. Severe wear and high friction are measured for all ball materials except when the balls have surface lubricant coatings.

  20. 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...

  1. 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).

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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)....

  7. 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.

  8. 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.

  9. 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 ...

  10. 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...

  11. 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.

  12. 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...

  13. NONLINEAR STABILITY OF BALANCED ROTOR DUE TO EFFECT OF BALL BEARING INTERNAL CLEARANCE

    Institute of Scientific and Technical Information of China (English)

    BAI Chang-qing; XU Qing-yu; ZHANG Xiao-long

    2006-01-01

    Stability and dynamic characteristics of a ball bearing-rotor system are investigated under the effect of the clearance in the ball bearing. Different clearance values are assumed to calculate the nonlinear stability of periodic solution with the aid of the Floquet theory. Bifurcation and chaos behavior are analyzed with variation of the clearance and rotational speed. It is found that there are three routes to unstable periodic solution.The period-doubling bifurcation and the secondary Hopf bifurcation are two usual routes to instability. The third route is the boundary crisis, a chaotic attractor occurs suddenly as the speed passes through its critical value. At last, the instable ranges for different internal clearance values are described. It is useful to investigate the stability property of ball bearing rotor system.

  14. 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.

  15. 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

  16. 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.)

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. The in-vacuo torque performance of dry-lubricated ball bearings at cryogenic temperatures

    Science.gov (United States)

    Gould, S. G.; Roberts, E. W.

    1989-01-01

    The performance of dry-lubricated, angular contact ball bearings in vacuum at a temperature of 20 degrees K has been investigated, and is compared with the in-vacuo performance at room temperatures. Bearings were lubricated using dry-lubricant techniques which have been previously established for space applications involving operations at or near room temperature. Comparative tests were undertaken using three lubricants: molybdenum disulphide, lead, and PTFE. Results obtained using the three lubricants are presented.

  2. 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.

  3. 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.

  4. 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...

  5. 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℃.

  6. 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...

  7. A parametric heat transfer study for cryogenic ball bearings in SSME HPOTP

    Science.gov (United States)

    Chyu, Mingking K.

    1989-01-01

    A numerical modeling is to examine the effects of coolant convective heat transfer coefficient and frictional heating on the local temperature characteristics of a ball element in Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump (HPOTP) bearing. The present modeling uses a control-volume based, finite-difference method to solve the non-dimensionalized heat conduction equation in spherical coordinate system. The dimensionless temperature is found as a function of Biot number, heat flux ratio between the two race contacts, and location in the ball. The current results show that, for a given cooling capability, the ball temperature generally increases almost linearly with the heat input from the race-contacts. This increase is always very high at one of the two contacts. An increase in heat transfer coefficient generally reduces the ball temperature and alleviates the temperature gradient, except for the regions very close to the race contacts. For a 10-fold increase of heat transfer coefficient, temperature decrease is 35 percent for the average over entire ball, and 10 percent at the inner-race contact. The corresponding change of temperature gradient displays opposing trends between the regions immediately adjacent to the contacts and the remaining portion of the ball. The average temperature gradient in the vicinity of both contacts increases approximately 70 to 100 percent. A higher temperature gradient produces excessive thermal stress locally which may be detrimental to the material integrity. This, however, is the only unfavorable issue for an increase of heat transfer coefficient.

  8. Fast-steering Mirror with Self-aligning ball bearing Supporting Structure

    Science.gov (United States)

    Xu, Xinhang; Wang, Bing; Han, Xudong

    2012-10-01

    A fast-steering mirror (FSM) with self-aligning ball bearing supporting structure was designed to accurately control the transmission direction of high-octane laser. First, linear voice coil actuators were selected and SiC mirror, rigid supporting structure, precise grating sensors for measuring mirror position were designed respectively on the basis of the fast-steering mirror working conditions and performing requirements. After finishing accurately manufacturing and assembling of mechanism parts, the servo control system was constituted, and then the designed FSM system was tested by experiments. The results showed that the FSM with self-aligning ball bearing supporting structure has not only great carrying capacity and resonance frequency, but it also has excellent angle stability (the stable precision of mirror is more than 2″). Furthermore, the FSM system has great adaptability to vibrancy, impact and rotation. Therefore, the designed FSM can satisfy application requirements of precise beam control system.

  9. Research on Quality Inspection and Sorting On-line System for Bearing Steel Ball

    Directory of Open Access Journals (Sweden)

    Yu Runxiang

    2015-01-01

    Full Text Available To detect the flaws of bearing steel ball and sort its quality on-line, a kind of online quality detecting and sorting system for bearing steel ball is developed, which based on the eddy current inspection theory. The design of scheme, circuit and mechanical structure of the system is described in detail. PSD(Phase Sensitive Detection is applied to pick up the signal of cracks and restrain interferential signal. The flaws will be quantificational analysed based on the X-R orthogonal decomposition technology which include the size and depth information of flaws. By analysing and processing the amplitude and phase of the defect signal, the flaws can be found with high accuracy and low error-detected ratio. ARM and MCU Processor ensures the real-time ability of discriminating algorithm. The CPLD is used for generating reference signal which can be easy to get synchronous with the source signal. It has good properties of real-time to detect the quality of bearing steel ball.

  10. 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...

  11. Analisis Sinyal Getaran untuk Menentukan Jenis dan Tingkat Kerusakan Bantalan Bola (Ball Bearing

    Directory of Open Access Journals (Sweden)

    Suhardjono Suhardjono

    2004-01-01

    Full Text Available An Engineer can determine accurately the type and the level of engine faults using vibration-signal, like a doctor investigates his/her patient by analyzing the hart beat. Vibration is a response of a mechanical system caused by both excitation forces and the changes of operating conditions that vary within certain limits. The excitation forces introduced by several sources such as contact between moving elements, unbalanced mass, misalignments, ball bearing defects, which is the topic of this research may be arised. There are two kinds of bearing defects, local and distributed defects. The most cases of local defects are the defect of inner and outer raceway also rolling elements. Moreover the most cases of distributed defects are the unroundness of inner and outer raceway, missalignment of inner and outer raceway, ununiformed ball dimension. Furthermore, for many machine elements such as ball bearing, the vibration has a typical level, and its frequency spectrum has a characteristic shape when the machine is in good condition or defect. The most popular and the latest sophisticated method to detect bearing defect is computer-based vibration monitoring. This method analyzes the measured vibration-signal in both time and frequency domain. An experiment to detect the type and the level of ball bearing defects has been done in bench grinding machine by changing such a certain defect of bearing elements. A comparison of the vibration-signal of the good condition and the defect one can be determined the type and the level of such a bearing defect. In general the result of this experiment showed that the vibration-signal of the good bearing is a harmonic, but the defect one has a random signal. For determining the type of defect of bearing elements, the frequency must be synchronized with the calculation of bearing parameters such as inner and outer raceway diameters, number of balls and number of rotations. The application of this research is the

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Computation of Space Shuttle high-pressure cryogenic turbopump ball bearing two-phase coolant flow

    Science.gov (United States)

    Chen, Yen-Sen

    1990-01-01

    A homogeneous two-phase fluid flow model, implemented in a three-dimensional Navier-Stokes solver using computational fluid dynamics methodology is described. The application of the model to the analysis of the pump-end bearing coolant flow of the high-pressure oxygen turbopump of the Space Shuttle main engine is studied. Results indicate large boiling zones and hot spots near the ball/race contact points. The extent of the phase change of the liquid oxygen coolant flow due to the frictional and viscous heat fluxes near the contact areas has been investigated for the given inlet conditions of the coolant.

  17. 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.

  18. 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)

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

    Science.gov (United States)

    Hergert, Robert J.; Hanrahan, Brendan; Ghodssi, Reza; Holmes, Andrew S.

    2013-06-01

    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.

  20. 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,...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. An evaluation of various ball bearing lubricants operating in various environments /A status report/. [fluid and solid lubricants tests

    Science.gov (United States)

    Demorest, k. E.; Mcmurtrey, E. L.

    1975-01-01

    Testing of both fluid and solid lubricants in small ball bearings is reported for a period of up to one year in various environments. The testing equipment, procedures and detailed results of five different lubricants, operating in a vacuum at ambient temperature, are described. Specially made motors were shimmed to maintain a 2.27 kg thrust load on both bearings, having a speed of 3600 rpm allowing 216,000 revolutions on each bearing per hour until failure. The commercial perfluoropolyether (PFPE-1) grease, having the best results, was recommended for long term bearing operation under hard vacuum conditions. It had an average life of over 8760 hrs. The ester based grease was recommended for moderate life requirements in vacuum conditions, while the silicone based grease and the fluorosilicone based grease were not recommended for vacuum operation due to extensive metal damage in the bearings.

  7. 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...

  8. 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.

  9. 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.

  10. Improvement on assembly process for deep groove ball bearing with ball gap%带装球缺口深沟球轴承装配工艺的改进

    Institute of Scientific and Technical Information of China (English)

    李香; 温晶

    2015-01-01

    In view of inefifciency of manual pressing ball craft, the labor intensity being big and being easy to miss balls about deep groove ball bearings with ball gap,a kind of automatic assembly balls machine was developed to realize the function of automatic iflling balls and automatic moving products, improve the production efifciency, degree of automation and reliability, reduce the labor intensity of the workers.%针对带装球缺口的深沟球轴承手工压球工艺生产效率低、劳动强度大、且容易漏球的问题,研制了自动装球机,实现了自动装球、自动下料的功能,提高了生产效率、自动化程度和可靠性,减轻了工人的劳动强度。

  11. 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.

  12. Suomi-NPP Mission On-Orbit Experience with Toroid Ball Bearing Retainers Under Unidirectional and Reversing Motion

    Science.gov (United States)

    Bruegman, Otto; Thakore, Kamal; Loewenthal, Stu; Cymerman, John

    2016-01-01

    The Advanced Technology Microwave Sounder (ATMS) instrument scan system on the Suomi National Polar-orbiting Partnership (SNPP) spacecraft has experienced several randomly occurring increased torque 'events' since its on-orbit activation in November 2011. Based on a review of on-orbit telemetry data and data gathered from scan mechanism bearing life testing on the ground, the conclusion was drawn that some degradation of Teflon toroid ball retainers was occurring in the instrument Scan Drive Mechanism. A life extension program was developed and executed on-orbit with very good results to date. The life extension program consisted of reversing the mechanism for a limited number of consecutive scans every day.

  13. 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...

  14. The influence of lubrication on the dynamic behaviour of ball bearings

    NARCIS (Netherlands)

    Wijnant, Y.H.; Wensing, J.A.; Nijen, G.C.

    1999-01-01

    Investigation into the dynamic behaviour of rolling element bearings is motivated by the urge to reduce vibrations in rolling bearing applications. The dynamics of the bearing is governed by both the dynamics of its structural elements, i.e., the inner ring, the outer ring and the rolling elements,

  15. The Dynamics Simulation of the Deep Groove Ball Bearing Based on LS-DYNA%基于LS-DYNA深沟球轴承的动力学仿真

    Institute of Scientific and Technical Information of China (English)

    康晓晨; 乔长帅; 吴楠

    2013-01-01

    基于ANSYS/LS-DYNA建立了深沟球轴承的有限元模型,有效处理了考虑摩擦条件的接触问题,实现了深沟球轴承显式动力学的运动过程仿真。并以6203深沟球轴承为例,进行了动力学仿真与分析。%The finite element model of deep groove ball bearing was established based on ANSYS/LS-DYNA, effectively deal with the contact problem with friction condition,the explicit dynamic simulation of deep groove ball bearing was realized. Taking the 6203 deep groove ball bearing as an example,the dynamics simulation and analysis is carried out.

  16. 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.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 深沟球轴承接触力学特性分析%Analysis of Contact Mechanics Characteristic of Deep Groove Ball Bearing

    Institute of Scientific and Technical Information of China (English)

    谢伟; 姚廷强

    2012-01-01

    The contact mechanics characteristic analysis of roll bearing is a basic problem in bearing analysis. The mesh element size of the local contact area between ball and the raceway has a critical influence on the contact stress simulation results by finite element method. Based on ANSYS simulation platform, the ball - cut - area method is proposed to refine the mesh of the contact area and multi pairs surface - surface contact relationship are established, then the multi - body and multi - contact pairs finite element model of ball bearing is established. Taking deep groove ball bearing 6012 as example, the load distribution of deep groove ball bearing under the static radial force is analyzed . Comparing the calculation results of the contact stress between simulation results and the calculation results by Hertz theory, both is in good agreement, it is verified the simulation result is correct, and the basis for the further study of the bearing is provided.%滚动轴承接触力学特性的分析是轴承分析的一个基础问题,钢球与套圈滚道的局部接触区域的网格单元尺寸对接触应力的有限元法仿真计算结果有着至关重要的影响.基于ANSYS仿真平台,提出了利用球切区域方法局部细化接触区网格,建立多对局部区域的面-面接触关系,从而建立球轴承多体多接触对有限元仿真模型.以深沟球轴承6012为实例,分析了深沟球轴承在静径向力下的载荷分布,将接触应力的仿真分析结果与Hertz理论计算结果进行对比,两者较好的吻合,验证了仿真分析结果是正确的,为轴承的进一步研究提供依据.

  7. Research activities of hybrid ceramic ball bearings for turbochargers in research and development center, Koyo Seiko; Koyo seiko sogo kenkyusho ni okeru turbocharger yo ceramic tamajikuuke no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Tanimoto, K. [Koyo Seiko Co. Ltd., Osaka (Japan)

    2000-05-20

    Silicon nitride ceramics developed at Hikari Seiko's General Technology Research Institute was applied for the first time in the world in 1998 to balls used in bearing for turbo chargers for commercially available passenger cars. This paper reports the summary thereof. Silicon nitride used in the ceramic ball bearing is a high quality ceramic material that uses yttrium oxide and aluminum oxide as sintering auxiliaries, and is treated with hot static water pressure and made denser. Characteristics of low density as compared to that of high-carbon chrome bearing steel used as the general bearing steel are as follows: bearing weight, and ball's centrifugal force under high speed rotation are reduced; its heat resistance makes use of bearing possible under elevated temperatures; and shared bondage reduces seizing due to running out of oil film when the bearing is rotated at high speeds. Thus, the material is well suitable for turbo chargers. Its rolling fatigue life exceeds that of the bearing steel, and it is made clear that the damage pattern is exfoliation similar to that in the bearing steel. A life test for the ceramic ball bearing showed a result exceeding the calculated life time. (NEDO)

  8. 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,...

  9. 球轴承涡轮增压器轴承-转子系统动力学分析与应用∗%Analysis and Application of Rotor Dynamics of Bearing-rotor System of Ball Bearing Turbocharger

    Institute of Scientific and Technical Information of China (English)

    刘大诚; 史立伟

    2014-01-01

    相比于普遍使用的浮动轴承,在涡轮增压器中使用球轴承具有机械效率高和加速响应快的优势。以车用球轴承涡轮增压器为研究对象,用有限元法对轴承-转子系统进行了转子动力学特性的研究,对轴承-转子系统的临界转速进行了计算与分析,这是判断转子工作转速是否稳定和涡轮增压器工作是否可靠的重要依据;建立了增压器模型,并对比了计算结果和试验结果,证明了方法的可行性。通过整机试验表明,球轴承涡轮增压器能够满足当前车用发动机的需求,能够提高发动机的工作性能。%Turbochargers in ball bearings have much advantage than floating busing bearings,such as high mechanical efficiency and fast accelerate response.The paper studied obj ect that was ball bearing turbocharger of vehicle,researched on rotor dynamic characteristics of bearing-rotor system,and used finite element method to analyze the critical speed of bearing-rotor system which is the very important basis to j udging whether the rotor work is stable and turbocharger work is reliable. Comparing and analyzing the computing and experimental results,it proves the feasibility and accuracy of setting up model on bearing-rotor system of ball bearing turbocharger.After the test of prototype,it was proved that ball bearing turbo-charger can meet the current needs of vehicle engine and improve the working performance of the engine.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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,...

  16. 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.

  17. 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?

  18. 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.

  19. 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.

  20. 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...

  1. 深沟球轴承自动清洗线工装改进%Improvement of automated cleaning line tooling of deep groove ball bearings

    Institute of Scientific and Technical Information of China (English)

    李鸿刚; 王忠生

    2011-01-01

    深沟球轴承在自动清洗线清洗时,由于清洗煤油、防锈油、过滤芯子更换周期和喷油管线安装位置的影响,轴承的清洗质量无法保证。针对以上问题,对自动清洗线工装进行改进,提高清洗质量,满足工艺要求。%During cleaning the deep groove ball bearings in the automatic cleaning line, as the impact of replacement cycle of the cleaning kerosene, anti-rust oil, filter wick and oil injection pipeline installation location, the cleaning quality of bearings could not be guaranteed. The tooling of automatic cleaning line was improved to solve the above problem, then the cleaning quality was too increased and the technological requirements were met.

  2. 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.

  3. Ball bearing measurement based on white-light interferometry technique%白光干涉技术在球轴承测量中的应用

    Institute of Scientific and Technical Information of China (English)

    石炜; 李俊成; 韩军; 王建国; 王靖禹

    2014-01-01

    In order to achieve rapid and accurate measurement of sphere bearing ball during manufacturing process , a set of Michelson interferometer measurement system was proposed based on white light interferometer technology , image processing technology and signal processing technology .White light interferometry technique was analyzed theoretically . The precision and roughness measurement of the optical spherical radius of sphere ball bearing were made .The finish resolution image and the curvature radius image were obtained .The accurate calculation data was obtained after processing a large number of experimental data .The finish resolution can reach the nm level and the curvature can be calculated to theμm level.The processing quality and the detection speed are improved .%为了实现球轴承中球体在制造加工中快速准确的测量,采用白光干涉技术、图像处理技术和信号处理技术组建了一整套的基于迈克尔逊干涉仪的测量系统。对白光干涉技术进行了理论分析,对轴承球体进行了光学球面半径的高精度测量和粗糙度测量,取得了光洁度图像和曲率半径图像。在大量实验论证的基础上经过处理和计算得到了精确的计算数据,光洁度分辨率可达到纳米量级,曲率也可以计算到微米量级。结果表明,利用此技术可以对球面进行快速精确的测量,提高了加工质量和检测速度。

  4. 双半内圈角接触球轴承有限元分析%Finite element analysis of angular contact ball bearing with double half inner ring

    Institute of Scientific and Technical Information of China (English)

    赵燕; 公平; 徐雷

    2015-01-01

    在对双半内圈角接触球轴承进行合理的建模和网格划分后,通过PERMAS有限元软件对轴承接触应力进行有限元分析,了解该轴承应力分布状况,为轴承的性能分析提供了依据。%After carrying on reasonable modeling and grid division meshing for angular contact ball bearing with double half inner ring, ifnite element analysis of contact stress of bearing was carried on by PERMAS ifnite element software in order to understand the status of the bearing stress distribution and provide the basis for the bearing performance analysis.

  5. Damping Bearings In High-Speed Turbomachines

    Science.gov (United States)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  6. 基于ANSYS的角接触混合陶瓷球轴承接触分析%Contact Analysis of Angular Contact Hybrid Ceramic Ball Bearing Based on ANSYS

    Institute of Scientific and Technical Information of China (English)

    沈禾凯; 张淳; 郑甲红

    2011-01-01

    This aritcal takes the angular contact hybrid ceramic ball bearing whose specification is VEX65/NS 7CE1 as zhe research object, establishes analytical model based on FEA of ANSYS, gives a minute description to contact analysis of ball bearing about the logical simplification of the model and the set up of boundary conditions than solves the problem,thus it has important guiding significance on the further study on failure damage and on Rolling Bearing-Spindle System.%以VEX65/NS 7CE1角接触陶瓷球轴承为研究对象,建立了基于ANSYS的有限元分析模型,对轴承的接触分析中模型的合理简化和边界条件的设定作了详尽的说明并进而求解.其结果对进一步研究陶瓷球轴承的疲劳破坏及转子系统的研究提供了重要指导基础.

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Numerical Simulation on Hot Helical Rolling Forming Process of blank for Bearing Steel Balls%轴承钢球毛坯热斜轧成形过程数值模拟

    Institute of Scientific and Technical Information of China (English)

    曹强; 华林; 钱东升

    2015-01-01

    Due to the complexity of process design and deformation behaviors during the hot helical rolling of bland for bearing steel balls,the traditional methods of analytical calculation and physical experiments are difficult to investigate its rolling deformation mechanisms.The main modeling techniques and methods for hot helical rolling forming of steel balls are discussed and summarized,and a 3D coupled thermo-mechanical finite element simulation model is firstly de-veloped based on SIMUFACT finite element software platform.Based on finite element simulation results,the distribution and evolution rules of equivalent strain,stress,temperature and rolling force and power parameters during hot helical roll-ing forming process of bland for bearing steel balls are analyzed in detail.It is proved that the central loosen or cavity de-fects during helical rolling of blank for steel ball is the combination result of circular-alternating shear stress,higher lev-el transverse tensile stress and larger negative hydrostatic pressure (positive mean stress)caused by multi -directional tensile stresses.%轴承钢球毛坯螺旋孔型斜轧工艺设计和变形行为较为复杂,传统的解析计算和物理试验方法不能有效揭示其轧制变形机理。探讨总结了钢球毛坯热斜轧成形主要建模技术与方法,基于SIMUFACT有限元软件平台首次建立了钢球毛坯热斜轧成形三维热力耦合有限元仿真模型。基于有限元模拟结果详细分析了轴承钢球毛坯热斜轧成形过程等效应变、应力、温度和轧制力能参数的分布与演变规律,证明钢球毛坯斜轧心部疏松或空洞缺陷的产生是由其在轧制过程承受的循环交变切应力、较高水平的横向拉应力和由多向拉应力引起的较大负静水压应力(正的平均应力)共同作用的结果。

  13. 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...

  14. 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

  15. 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.

  16. 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.

  17. 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...

  18. Contact Stress FEM analysis of Deep Groove Ball Bearing Based on ANSYS Workbench%基于ANSYS Workbench的深沟球轴承接触应力有限元分析

    Institute of Scientific and Technical Information of China (English)

    张福星; 郑源; 汪清; 李杰; 徐素红; 辛华荣; 吴忠

    2012-01-01

    利用ANSYS Workbench软件建立了深沟球轴承的三维非线性接触模型,对模型的边界条件进行合理的设置后,基于有限元的方法,在Static Structural(ANSYS)中对深沟球轴承的接触应力和变形进行了仿真计算,得到了轴承滚动体和内、外圈不同部位接触应力和变形的分布.计算结果与Hertz理论解进行了对比,两者具有良好的一致性,说明了用ANSYS Workbench分析滚动轴承接触问题是可行的,符合轴承在载荷作用下受力和变形的实际情况;有限元仿真计算的结果为滚动轴承的设计、优化和失效分析提供了参考依据,具有一定的工程实用价值.%The 3D nonlinear contact model of a deep groove ball bearing was established in ANSYS Workbench sofiware.With the reasonable setting of the boundary conditions,the contact stress and deformation were calculated in Static Structural (ANSYS)by using the finite element method,and the contact stress and deformation of the inner ring, the outer ting and the rolling elements were obtained.Furthermore the computational values are consistent with the Hertz values.The results show that solving the bearing contact problem with ANSYS Workbench software is feasible and it coincides with the stress and deformation of the actual situation.The FEM results provide reference for the design, optimization and failure analysis of rolling bearings and have practical engineering value.

  19. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  20. 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...

  1. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  2. Fault Diagnosis for Deep Groove Ball Bearings Based on Wavelet Packet and BN Model%基于小波包和 BN 模型的深沟球轴承故障诊断

    Institute of Scientific and Technical Information of China (English)

    郭文强; 张宝嵘; 彭程; 夏令君; 佘金龙

    2016-01-01

    Aiming at uncertainty for faults of deep groove ball bearings used in drying section of paper -making ma-chine,the fault diagnosis method is presented based on wavelet packet and Bayes network.Firstly,the wavelet packet decomposition is carried out for captured vibration signals.Furthermore,the designed feature extraction function is uti-lized to processing signal,and the fault feature vector is formed after discretization.Then the prior parameter of BN model is obtained by training feature vector,and the network model for fault diagnosis of bearings is built.Finally,the proposed method is used to handles with uncertain representation and reasoning by exploiting the learning and probabi-listic inference abilities of BN,the fault diagnosis is finished.The experimental results show that the BN model pro-vides better performance than tradition BP neural network method at both diagnostic accuracy and training time cost. Particularly,the BN model has better reasoning and diagnosis effect when the feature vector of input fault is incomplete.%针对造纸机干燥部所用深沟球轴承故障的不确定性问题,提出了小波包与 Bayes 网络相结合的滚动轴承故障诊断方法。首先,对实测振动信号进行小波包分解;其次,利用设计的特征提取函数进一步处理信号,离散化后形成故障特征向量;然后,采用特征向量训练得到 BN 模型先验参数,建立轴承故障诊断网络模型;最后,充分利用 Bayes 网络的建模学习能力和概率推理算法解决不确定性问题的表示和推理,完成故障诊断。试验结果表明:BN 模型在诊断正确率、训练耗时上均优于传统 BP 神经网络方法,尤其可在输入故障特征向量不完备时,依然具有较好的推理诊断效果。

  3. 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…

  4. 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 ...

  5. 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...

  6. Pressure Bearing and Contact Analysis of Ball Injection Sliding Sleeve in Horizontal Well Staged Fracturing%水平井分段压裂投球滑套承压接触分析

    Institute of Scientific and Technical Information of China (English)

    徐玉龙; 程智远; 刘志斌; 李世恒; 韩永亮; 周后俊

    2012-01-01

    Due to the fact that there is no jection sliding sleeve for horizontal well staged mature matching tool for open hole completion in China, the ball infracturing suitable for Sulige Gasfield was developed. In light of the problem that the sleeve is not noticeably in place in fracturing operation, the finite element analysis software was adopted to establish the contact model of the sleeve and analyze the effect of different pressures on low-density ball, ball seat deformation and stress distribution. The analysis shows that when the operation pressure changes from 10 MPa to 20 MPa, the contact pressure is approximate to a linear change. When the pressure increases from 20 MPa to 50 MPa, the plastic deformation occurs between ball and ball seat, the contact area increases and the contact pressure increase slows down. When the pressure is 50 MPa, the maximum stress value of the ball seat reaches 358 MPa, exceeding the yield strength of low-density ball and ball seat to cause plastic deformation. But it does not reach the yield limit, satisfying the field operation requirement.%鉴于国内还没有成熟的裸眼完井配套工具,研制了适合苏里格气田的水平井分段压裂投球滑套,并针对投球滑套在压裂施工中到位不明显的问题,利用有限元分析软件ANSYS建立了投球滑套的接触模型,分析了不同压力对低密度球和球座变形与应力分布的影响。分析结果表明,施工压力由10 MPa增至20 MPa时,接触压力近似线性变化,当压力从20 MPa增加到50 MPa时,球和球座之间开始产生塑性变形,接触面积增加,从而使接触压力增加变慢。当压力为50 MPa时,球座最大应力值达到358 MPa,超过了低密度球和球座的屈服强度而发生了塑性变形,但是没有达到材料的屈服极限,满足压裂施工的要求。

  7. 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...

  8. 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.

  9. Optimized Coolant-Flow Diverter For Increased Bearing Life

    Science.gov (United States)

    Subbaraman, Maria R.; Butner, Myles F.

    1995-01-01

    Coolant-flow diverter for rolling-element bearings in cryogenic turbopump designed to enhance cooling power of flow in contact with bearings and thereby reduce bearing wear. Delivers jets of coolant as close as possible to hot spots at points of contact between balls and race. Also imparts swirl that enhances beneficial pumping effect. Used with success in end ball bearing of high-pressure-oxidizer turbopump.

  10. Ball Collision Experiments

    Science.gov (United States)

    Cross, R.

    2015-01-01

    Experiments are described on collisions between two billiard balls and between a bat and a ball. The experiments are designed to extend a student's understanding of collision events and could be used either as a classroom demonstration or for a student project.

  11. 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.

  12. Distance Geometry for Kissing Balls

    CERN Document Server

    Chen, Hao

    2012-01-01

    A kissing ball is a ball that is tangent to a fixed reference ball. In this paper, we will treat kissing balls with techniques from the Euclidean distance geometry. This turns out to be more general than the classical Euclidean distance geometry. We will show that the distance matrix for the kissing balls plays, at the same time, the role of Cayley-Menger matrix. Thus classical problems in Euclidean distance geometry will have new versions for kissing balls.

  13. 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).

  14. 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.

  15. Theory of ball lightning

    CERN Document Server

    Wu, H -C

    2014-01-01

    We present a comprehensive explanation on ball lightning, a luminous sphere occasionally witnessed after ordinary lightning. In the last decade, it has been well established that natural lightning routinely generates relativistic electrons, which account for observed x rays. So we assume that, in a ball lightning event, a well-defined relativistic electron bunch is produced by the stepped leader of lightning. When this electron bunch strikes various media, a powerful microwave pulse is emitted by the coherent transition radiation mechanism. This intense microwave ionizes air, evacuates plasmas by its radiation pressure to form a globular plasma cavity, and then gets trapped inside the cavity. This theory successfully explains all characteristics of ball lightning, especially the appearance of ball lightning in fully-screened aircraft. Moreover, the proposed radiation mechanism fully explains the strongest radio signals from lightning and nanosecond spikes in the signals are direct evidences on the generation ...

  16. Aerodynamics of sports balls

    Science.gov (United States)

    Mehta, R. D.

    1985-01-01

    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.

  17. 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.

  18. 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.

  19. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    Science.gov (United States)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  20. The bowling balls

    CERN Multimedia

    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...

  1. 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.

  2. 考虑转子系统耦合影响的球轴承动态性能多目标优化设计%Multi-objective optimization design for dynamic performances of ball bearings considering coupling effect of a rotor system

    Institute of Scientific and Technical Information of China (English)

    崔立; 郑建荣; 周炜

    2012-01-01

    Considering coupling effects of dynamic performances of rolling bearings and a rotor system, dynamic equations were constructed by using the finite element method, the rolor system contained a shaft, bearings, and discs. The dynamic performances of rolling bearings were calculated with a quasi-dynamic model after the rotor system response reached a stable state. Taking dynamic load, stiffness, and spin-to-roll ratio as objectives, a multi-objective optimization design was developed based on the genetic algorithm NSGA Ⅱ, the effect of structural parameters on bearing dynamic performances was analyzed. Taking a rotor system supported with ball bearings as an example, the results showed that the dynamic load decreases, radial stiffness increases and spin-to-roll ratio increases when the outer groove curvature radius increases; the dynamic load decreases, radial stiffness decreases and spin-to-roll ratio decreases as the inner groove curvature radius increases; the dynamic load increases, radial stiffness increases and spin-to-roll ratio increases when the diameter of balls increases; the largest effect on the dynamic performance optimization results is inner groove curvature radius; in a high-speed rotor system, in order to obtain better support dynamic performance, the coupling effect of the rotor system should be considered in multi-objective optimization design of its bearings.%考虑滚动轴承与转子系统动态性能的耦合影响,使用有限单元法建立包含转轴、轴承、圆盘等单元的动力学方程组,转子响应达到稳定值后,再根据滚动轴承拟动力学模型计算滚动轴承的动态性能参数.以额定动负荷、支承刚度、旋滚比为目标,基于NSGA Ⅱ遗传算法进行多目标优化设计,分析结构参数对轴承动态性能的影响.以某转子系统的支承轴承为例进行计算,结果表明外圈沟曲率半径系数增大则额定动负荷减小、径向刚度增大、旋滚比增大;内圈沟曲率

  3. Computer-aided selection of materials for cryogenic turbopump bearings

    Science.gov (United States)

    Maurer, R. E.; Pallini, R. A.

    1985-01-01

    The life requirement for the angular contact ball bearings in the Space Shuttle Main Engine (SSME) high-pressure-oxygen turbopump (HPOTP) is 7.5 hours. In actual operation, significantly shorter service life has been experienced. The objective of this current program is to identify bearing materials and/or materials processing techniques offering significant potential for extending HPOTP bearing performance life. A thermomechanical analysis of the HPOTP shaft/bearing system was performed with the SHABERTH (SHaft-BEaring-THermal) computer program. Bearing fatigue life, ball-race contact stress, heat generation rate, bulk ring temperatures, and circumferential stress in the inner rings were quantified as functions of radial load, thrust load, and ball-race contact friction. The analysis results were used to formulate criteria that are being used for the selection of special materials for future turbopump bearings.

  4. Have a Ball

    Institute of Scientific and Technical Information of China (English)

    程炜

    2003-01-01

    Before being sent to prison Carl drove big cars and ate in expensive restaurants. No one knew where he got his money but he was certainly having a ball. When the judge sentenced him.to prison he said, “I hope you have a bail, Carl.” To have a bait is to have a wonderful time.

  5. Bearing system

    Science.gov (United States)

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  6. 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}.

  7. 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。

  8. Improvement and Analysis of One-Way Honing to Inner Ball Surface of Spherical Plain Bearing%关节轴承内圈球面单程珩磨分析与改进

    Institute of Scientific and Technical Information of China (English)

    蔡士源

    2014-01-01

    Based on the one-way honing process of inner surface of spherical plain bearing,the principle of one-way honing and finishing process are analyzed,and the principle defects of one-way honing and finishing are illustrated.A method of the spherical round-trip honing and super-finishing technique to replace the one-way honing is put for-ward,and the function of round-trip honing and working principle and characteristics of super-finishing are expoun-ded.%基于关节轴承内圈球面单程珩磨工艺,分析单程珩磨的原理和光整作用过程,说明了单程珩磨光整的原理性缺陷,提出了替代方法即球面双程珩磨和超精加工技术,并阐述了双程珩磨的作用和超精加工的工作原理及特点。

  9. 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)

  10. 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.

  11. 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...

  12. Small, high-speed bearing technology for cryogenic turbo-pumps

    Science.gov (United States)

    Winn, L. W.; Eusepi, M. W.; Smalley, A. J.

    1974-01-01

    The design of 20-mm bore ball bearings is described for cryogenic turbo-machinery applications, operating up to speeds of 120,000 rpm. A special section is included on the design of hybrid bearings. Each hybrid bearing is composed of a ball bearing in series with a conventional pressurized fluid-film journal bearing. Full details are presented on the design of a test vehicle which possesses the capability of testing the above named bearings within the given speed range under externally applied radial and axial loads.

  13. 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.

  14. Autosizing Control Panel for Needle Bearing

    Directory of Open Access Journals (Sweden)

    Prof.A.R.Wadhekar,

    2016-02-01

    Full Text Available 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 housing itself. Radial bearings are cylindrical and they use rollers parallel to the axis of the shaft. Radial pattern of needle are being used by thrust needles. Complement bearings have solid inner as well as outer rings and rib-guided cylindrical rollers. The bearings have the largest number of rolling elements and also have extremely high radial load carrying capacity and are suitable for compact designs.Needle roller bearings have relatively small diameter cylindrical rolling elements whose length is much larger than their diameter. As compared to other types of rolling bearings, needle roller bearings possess a small cross-sectional height and significant load-bearing capacity and rigidity relative to their volume. Also, because the inertial force acting on them is limited, needle bearings are an ideal choice for applications with oscillating motion. These bearings also work well in compact and lightweight machine designs and they serve as a ready replacement for sliding bearings. Needle bearings features are great rigidity, smaller cross-section, higher loadcarrying capacity, and has lower inertia forces that facilitate to size and weight reductions in machinery. Needle bearings are designed to stand in oscillation, performwell under any conditions, and interchange with the sliding of bearings.

  15. Pratt and Whitney cryogenic turbopump bearing experience

    Science.gov (United States)

    Poole, W. E.; Bursey, R. W., Jr.

    1988-01-01

    Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

  16. Marshall Space Flight Center High Speed Turbopump Bearing Test Rig

    Science.gov (United States)

    Gibson, Howard; Moore, Chip; Thom, Robert

    2000-01-01

    The Marshall Space Flight Center has a unique test rig that is used to test and develop rolling element bearings used in high-speed cryogenic turbopumps. The tester is unique in that it uses liquid hydrogen as the coolant for the bearings. This test rig can simulate speeds and loads experienced in the Space Shuttle Main Engine turbopumps. With internal modifications, the tester can be used for evaluating fluid film, hydrostatic, and foil bearing designs. At the present time, the test rig is configured to run two ball bearings or a ball and roller bearing, both with a hydrostatic bearing. The rig is being used to evaluate the lifetimes of hybrid bearings with silicon nitride rolling elements and steel races.

  17. Recycling of heat discharged from bearing quenching

    Institute of Scientific and Technical Information of China (English)

    WEN Xin-lin; CI Tie-jun; WEN Peng; ZHANG Rong-ying

    2006-01-01

    In this paper,the technical method of cooling quench medium with air-cooler in the process of bearing quenching is introduced.The exhausted hot air is directly used to dry bearing balls.It is a novel approach for full utilization of heat energy during heat treatment,which increased 30% of the heat efficiency when compared with normal air-cooler methods that directly put exhaust air into atmosphere.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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…

  5. Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

    Directory of Open Access Journals (Sweden)

    Yang Shicai

    2016-01-01

    Full Text Available AISI 316 austenitic stainless steel balls (diameters 5.0 and 12.0 mm, typical hardness 250 HV0.3 and flat samples (20×20×2.0 mm were nitrided by a pulsed glow discharge Ar/N2 plasma. Hardness of the ball surfaces was analysed using Vickers indentation. Thermal stability of the nitrided balls (diameter 12.0 mm was studied using a furnace to heat them in air for 8 hours at temperatures up to 700.0°C and then, after cooling to room temperature, the surface hardness of the heated balls was re-measured. Scanning electron microscopy and X-ray diffraction were used to study the microstructures, composition and phase formation of the nitrided sublayers. Unlubricated pin-on-disc wear testing was used to evaluate the wear resistance of nitrided stainless steel balls (5.0 mm diameter and the results were compared with similar testing on hardened Cr-Steel balls (5 mm diameter with hardness of about 650 HV0.3. All the test results indicated that the nitrided AISI 316 austenitic stainless steel balls have advantages over the hardened Cr-Steel balls in terms of retaining high hardness after heat treatment and high resistance to sliding wear at room temperature under higher counterpart stress. These properties are expected to be beneficial for wide range of bearing applications.

  6. 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...

  7. 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...

  8. 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...

  9. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  10. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  11. 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.

  12. 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)

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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)

  18. 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.

  19. 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)

  20. 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.

  1. Striking results with bouncing balls

    NARCIS (Netherlands)

    A. Heck; T. Ellermeijer; E. Kędzierska

    2008-01-01

    In a laboratory activity students study the behaviour of a bouncing ball. With the help of a high-speed camera they can study the motion in detail. Computer modelling enables them to relate the measurement results to the theory. They experience that reality (measurements) is not automatically in lin

  2. 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.

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Bearing tester data compilation, analysis and reporting and bearing math modeling, volume 1

    Science.gov (United States)

    Marshall, D. D.; Montgomery, E. E.; New, L. S.; Stone, M. A.; Tiller, B. K.

    1984-01-01

    Thermal and mechanical models of high speed angular contact ball bearings operating in LOX and LN2 were developed and verified with limited test data in an effort to further understand the parameters that determine or effect the SSME turbopump bearing operational characteristics and service life. The SHABERTH bearing analysis program which was adapted to evaluate shaft bearing systems in cryogenics is not capable of accommodating varying thermal properties and two phase flow. A bearing model with this capability was developed using the SINDA thermal analyzer. Iteration between the SHABERTH and the SINDA models enable the establishment of preliminary bounds for stable operation in LN2. These limits were established in terms of fluid flow, fluid inlet temperature, and axial load for a shaft speed of 30,000 RPM.

  9. 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.

  10. 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...

  11. 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...

  12. Fluid Mechanics of Cricket and Tennis Balls

    Science.gov (United States)

    Mehta, Rabindra D.

    2009-11-01

    Aerodynamics plays a prominent role in defining the flight of a ball that is struck or thrown through the air in almost all ball sports. The main interest is in the fact that the ball can often deviate from its initial straight path, resulting in a curved, or sometimes an unpredictable, flight path. It is particularly fascinating that that not all the parameters that affect the flight of a ball are always under human influence. Lateral deflection in flight, commonly known as swing, swerve or curve, is well recognized in cricket and tennis. In tennis, the lateral deflection is produced by spinning the ball about an axis perpendicular to the line of flight, which gives rise to what is commonly known as the Magnus effect. It is now well recognized that the aerodynamics of sports balls are strongly dependent on the detailed development and behavior of the boundary layer on the ball's surface. A side force, which makes a ball curve through the air, can also be generated in the absence of the Magnus effect. In one of the cricket deliveries, the ball is released with the seam angled, which trips the laminar boundary layer into a turbulent state on that side. The turbulent boundary layer separates relatively late compared to the laminar layer on the other side, thereby creating a pressure difference and hence side force. The fluid mechanics of a cricket ball become very interesting at the higher Reynolds numbers and this will be discussed in detail. Of all the round sports balls, a tennis ball has the highest drag coefficient. This will be explained in terms of the contribution of the ``fuzz" drag and how that changes with Reynolds number and ball surface wear. It is particularly fascinating that, purely through historical accidents, small disturbances on the ball surface, such as the stitching on cricket balls and the felt cover on tennis balls are all about the right size to affect boundary layer transition and development in the Reynolds numbers of interest. The fluid

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. Left atrial ball valve thrombus

    Directory of Open Access Journals (Sweden)

    R. Balaji

    2013-10-01

    Full Text Available "Ball valve thrombus" which is a spherical free floating clot in left atrium is an often quoted, but uncommonly encountered complication in patients with severe mitral stenosis of rheumatic origin, who are in atrial fibrillation. We describe the case of a 31-year-old lady with rheumatic heart disease, severe mitral stenosis and moderately severe aortic stenosis who had undergone closed mitral valvotomy 13 years ago. The patient presented with an episode of non-exertional syncope and breathlessness on exertion of 6 months duration and was in normal sinus rhythm. Echocardiography facilitated ante-mortem diagnosis and prompt institution of surgery was life saving.

  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. 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.

  3. 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.

  4. 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)

  5. Delayed Equation for Charged Rigid Nonrelativistic Ball

    CERN Document Server

    Vlasov, A A

    2002-01-01

    Simple expression for self-force acting on radiating rigid charged ball is derived (Sommerfeld ball). It is shown that appropriate delayed equation of motion has solutions in general differ from that for Sommerfeld sphere - there are no "radiationless" solutions, but there are oscillating without damping solutions though self-force has nonzero value.

  6. 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

  7. Misalignment in Gas Foil Journal Bearings: An Experimental Study

    Science.gov (United States)

    Howard, Samuel A.

    2008-01-01

    As gas foil journal bearings become more prevalent in production machines, such as small gas turbine propulsion systems and microturbines, system-level performance issues must be identified and quantified in order to provide for successful design practices. Several examples of system-level design parameters that are not fully understood in foil bearing systems are thermal management schemes, alignment requirements, balance requirements, thrust load balancing, and others. In order to address some of these deficiencies and begin to develop guidelines, this paper presents a preliminary experimental investigation of the misalignment tolerance of gas foil journal bearing systems. Using a notional gas foil bearing supported rotor and a laser-based shaft alignment system, increasing levels of misalignment are imparted to the bearing supports while monitoring temperature at the bearing edges. The amount of misalignment that induces bearing failure is identified and compared to other conventional bearing types such as cylindrical roller bearings and angular contact ball bearings. Additionally, the dynamic response of the rotor indicates that the gas foil bearing force coefficients may be affected by misalignment.

  8. 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

  9. 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...

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Observations of Spacecraft Bearing Lubricant Redistribution Based on Thermal Conductance Measurements

    Science.gov (United States)

    Takeuchi, Yoshimi R.; Frantz, Peter P.; Hilton, Michael R.

    2014-01-01

    The performance and life of precision ball bearings are critically dependent on maintaining a quantity of oil at the ball/race interface that is sufficient to support a robust protective film. In space applications, where parched conditions are intentionally the norm, harsh operating conditions can displace the small reserves of oil, resulting in reduced film thickness and premature wear. In the past, these effects have proven difficult to model or to measure experimentally. This paper describes a study addressing this challenge, where bearing thermal conductance measurements are employed to infer changes in lubricant quantity at the critical rolling interfaces. In the first part of the paper, we explain how the lubricant's presence and its quantity impacts bearing thermal conductance measurements. For a stationary bearing, we show that conductance is directly related to the lubricant quantity in the ball/race contacts. Hence, aspects of bearing performance related to oil quantity can be understood and insights improved with thermal conductance data. For a moving bearing, a different mechanism of heat transfer dominates and is dependent on lubricant film thickness on the ball. In the second part of the report, we discuss lubricant quantity observations based on bearing thermal conductance measurements. Lubricant quantity, and thus bearing thermal conductance, depends on various initial and operating conditions and is impacted further by the run-in process. A significant effect of maximum run-in speed was also observed, with less oil remaining after obtaining higher speeds. Finally, we show that some of the lubricant that is displaced between the ball and race during run-in operation can be recovered during rest, and we measure the rate of recovery for one example.

  19. 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.)

  20. Laryngeal Fracture Caused by a Lacrosse Ball.

    Science.gov (United States)

    Trinidade, Aaron; Shakeel, Muhammad; Stickle, Brian; Ah-See, Kim W

    2015-11-01

    Neck injuries in lacrosse are rare and mostly involve the musculoskeletal system. The lacrosse ball is a solid rubber ball of approximately 20 cm in diameter and the fastest shot recorded in professional lacrosse is over 100 mph. Despite wearing full protection, the neck remains prone to blunt trauma by this ball. A 23-year man sustained a direct blow to his left neck by a lacrosse ball during play, resulting in immediate aphonia and stridor. CT scan confirmed a left thyroid lamina fracture. The patient was treated conservatively and his airway was monitored for 24 hours. He made a full recovery. It is important that lacrosse players should be aware of this potential injury and appropriate precautions should be taken to avoid this trauma. PMID:26577976

  1. Hyperbolic monotonicity in the Hilbert ball

    Directory of Open Access Journals (Sweden)

    Reich Simeon

    2006-01-01

    Full Text Available We first characterize -monotone mappings on the Hilbert ball by using their resolvents and then study the asymptotic behavior of compositions and convex combinations of these resolvents.

  2. 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.

  3. 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.

  4. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025).

  5. 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.

  6. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yoon Jae; Ranjit, Shrestha; Kim, Won Tae [Dept. of Mechanical and Automotive Engineering, Kongju National University, Cheonan(Korea, Republic of)

    2015-06-15

    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.

  8. 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.

  9. 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.

  10. Large deflection analysis of a tension-foil bearing

    Science.gov (United States)

    Elrod, David A.

    1996-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are as follows: rolling or sliding contact within the bearing has life-limiting consequences; and REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's. CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contacts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exist for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. Recently, a new tension-foil bearing configuration has been proposed for turbomachinery applications.

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Evaluation of a hybrid hydrostatic bearing for cryogenic turbopump application

    Science.gov (United States)

    Spica, P. W.; Hannum, N. P.; Meyer, S. D.

    1986-01-01

    A hybrid hydrostatic bearing was designed to operate in liquid hydrogen at speeds to 80,000 rpm and radial loads to 440 n (100 lbf). The bearing assembly consisted of a pair of 20-mm angular-contact ball bearings encased in a journal, which was in turn supported by a fluid film of liquid hydrogen. The size and operating conditions of the bearing were selected to be compatible with the operating requirements of an advanced technology turbopump. Several test parameters were varied to characterize the bearing's steady-state operation. The rotation of the tester shaft was varied between 0 and 80,000 rpm. Bearing inlet fluid pressure was varied between 2.07 and 4.48 MPa (300 and 650 psia), while the fluid sump pressure was independently varied between 0.34 and 2.07 MPa (50 and 300 psia). The maximum radial load applied to the bearing was 440 N (110 lbf). Measured hybrid-hydrostatic-bearing stiffness was 1.5 times greater than predicted, while the fluid flow rate through the bearing was 35 to 65 percent less than predicted. Under two-phase fluid conditions, the stiffness was even greater and the flow rate was less. The optimal pressure ratio for the bearing should be between 0.2 and 0.55 depending on the balance desired between bearing efficiency and stiffness. Startup and shutdown cyclic tests were conducted to demonstrate the ability of the hybrid-hydrostatic-bearing assembly to survive at least a 300-firing-duty cycle. For a typical cycle, the shaft was accelerated to 50,000 rpm in 1.8 sec. The bearing operated for 337 start-stop cycles without failure.

  17. 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...

  18. 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

  19. 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.

  20. 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.

  1. Silicon ball grid array chip carrier

    Science.gov (United States)

    Palmer, David W.; Gassman, Richard A.; Chu, Dahwey

    2000-01-01

    A ball-grid-array integrated circuit (IC) chip carrier formed from a silicon substrate is disclosed. The silicon ball-grid-array chip carrier is of particular use with ICs having peripheral bond pads which can be reconfigured to a ball-grid-array. The use of a semiconductor substrate such as silicon for forming the ball-grid-array chip carrier allows the chip carrier to be fabricated on an IC process line with, at least in part, standard IC processes. Additionally, the silicon chip carrier can include components such as transistors, resistors, capacitors, inductors and sensors to form a "smart" chip carrier which can provide added functionality and testability to one or more ICs mounted on the chip carrier. Types of functionality that can be provided on the "smart" chip carrier include boundary-scan cells, built-in test structures, signal conditioning circuitry, power conditioning circuitry, and a reconfiguration capability. The "smart" chip carrier can also be used to form specialized or application-specific ICs (ASICs) from conventional ICs. Types of sensors that can be included on the silicon ball-grid-array chip carrier include temperature sensors, pressure sensors, stress sensors, inertia or acceleration sensors, and/or chemical sensors. These sensors can be fabricated by IC processes and can include microelectromechanical (MEM) devices.

  2. 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.

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

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

    2013-01-01

    In modern turbo-machinery gas journal bearings have been increasingly adopted, because they can operate at higher speed than most bearing designs. The main disadvantage of gas bearings is their low dynamic stability range. One solution to improve this and their performance is to combine...... the aerodynamic effect with the addition of external pressurization in a hybrid gas bearing. This study uses a mathematical model for hybrid lubrication of a compressible fluid film journal bearing with adjustable control of the external pressure, developed previously in [12]. The model is based on a compressible...... 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...

  4. 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.

  5. Electrostatic charge bounds for ball lightning models

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Karl D [Department of Technology, Texas State University, San Marcos, TX 78666 (United States)], E-mail: kdstephan@txstate.edu

    2008-03-15

    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.

  6. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-06-22

    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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Levitation of an iron ball in midair without active control

    Science.gov (United States)

    Sasaki, S.; Yagi, I.; Murakami, M.

    2004-02-01

    An iron ball floats in midair in a plastic box when several iron balls were attracted by a permanent magnet. A complex interaction between magnetized sphere materials and a lifting magnet enabled the suspension of an iron ball. The balls in the first row are simply attracted by the lifting magnet. The ball in the second row is also attracted by the lifting magnet, however, due to the repulsive forces exerted from the balls sitting above, it can float in midair. We also found that there are two stable positions for the ball to float. The floating ball could be transported from one equilibrium position to another by simply rotating the lifting magnet. This will make it possible to construct a noncontact load transport device.

  15. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  16. 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.

  17. 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.

  18. 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

  19. Introducing a High Bounce Ball Unit

    Science.gov (United States)

    Bernardo, Pat

    2004-01-01

    Those growing up in the 1950s, 60s or 70s are familiar with how physically active children were before computers and video games were introduced. Each neighborhood had its own version of the various games that were played. Many of these games involved a pink rubber ball called a Spaldeen. They were everywhere and almost everyone had one. These…

  20. 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…

  1. 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.

  2. 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.

  3. 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...

  4. 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

  5. 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.

  6. 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)

  7. 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.

  8. 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.

  9. 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...

  10. 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…

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Model-Based Control Design for Flexible Rotors Supported by Active Gas Bearings - Theory & Experiment

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo

    the critical speeds. In order to overcome such limitations, a mechatronic device has been proposed as a possible solution. This device named "hybrid active radial gas bearing" or simply "active gas bearing", combines an aerodynamic gas journal bearing with piezoelectrically controlled injectors. In the present...... the effect of external pressurization. In order to validate the theoretical model, a test rig is used, which consists of a flexible rotor supported by a ball bearing and the active gas bearing. This thesis has three main focuses and original contributions: Firstly, contribute to improving a existing...... theoretical model for active gas bearings, with special attention to the modelling of the injection system. Secondly, experimentally validate the improved mathematical model in terms of static properties (journal equilibrium position and resulting aerodynamic forces) and dynamic properties (natural...

  16. The strange flight behaviour of slowly spinning soccer balls.

    Science.gov (United States)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-01-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights. PMID:23695000

  17. 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.

  18. Perceptual elements in Penn & Teller's "Cups and Balls" magic trick.

    Science.gov (United States)

    Rieiro, Hector; Martinez-Conde, Susana; Macknik, Stephen L

    2013-01-01

    Magic illusions provide the perceptual and cognitive scientist with a toolbox of experimental manipulations and testable hypotheses about the building blocks of conscious experience. Here we studied several sleight-of-hand manipulations in the performance of the classic "Cups and Balls" magic trick (where balls appear and disappear inside upside-down opaque cups). We examined a version inspired by the entertainment duo Penn & Teller, conducted with three opaque and subsequently with three transparent cups. Magician Teller used his right hand to load (i.e. introduce surreptitiously) a small ball inside each of two upside-down cups, one at a time, while using his left hand to remove a different ball from the upside-down bottom of the cup. The sleight at the third cup involved one of six manipulations: (a) standard maneuver, (b) standard maneuver without a third ball, (c) ball placed on the table, (d) ball lifted, (e) ball dropped to the floor, and (f) ball stuck to the cup. Seven subjects watched the videos of the performances while reporting, via button press, whenever balls were removed from the cups/table (button "1") or placed inside the cups/on the table (button "2"). Subjects' perception was more accurate with transparent than with opaque cups. Perceptual performance was worse for the conditions where the ball was placed on the table, or stuck to the cup, than for the standard maneuver. The condition in which the ball was lifted displaced the subjects' gaze position the most, whereas the condition in which there was no ball caused the smallest gaze displacement. Training improved the subjects' perceptual performance. Occlusion of the magician's face did not affect the subjects' perception, suggesting that gaze misdirection does not play a strong role in the Cups and Balls illusion. Our results have implications for how to optimize the performance of this classic magic trick, and for the types of hand and object motion that maximize magic misdirection.

  19. Detailed study of oxidation/wear mechanism in lox turbopump bearings

    Science.gov (United States)

    Chase, T. J.; McCarty, J. P.

    1993-12-01

    Wear of 440C angular contact ball bearings of the phase 2 high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME) has been studied by means of various advanced nondestructive techniques (NDT) and modeled with reference to all known material, design, and operation variables. Three modes dominating the wear scenario were found to be the adhesive/sheer peeling (ASP), oxidation, and abrasion. Bearing wear was modeled in terms of the three modes. Lacking a comprehensive theory of rolling contact wear to date, each mode is modeled after well-established theories of sliding wear, while sliding velocity and distance are related to microsliding in ball-to-ring contacts. Microsliding, stress, temperature, and other contact variables are evaluated with analytical software packages of SHABERTH(TM)/SINDA(TM) and ADORE(TM). Empirical constants for the models are derived from NIST experiments by applying the models to the NIST wear data. The bearing wear model so established precisely predicts quite well the average ball wear rate for the HPOTP bearings. The wear rate has been statistically determined for the entire population of flight and development bearings based on Rocketdyne records to date. Numerous illustrations are given.

  20. 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).

  1. 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.

  2. Dust ball physics and the Schwarzschild metric

    CERN Document Server

    Kassner, Klaus

    2016-01-01

    A physics-first derivation of the Schwarzschild metric is given. Gravitation is described in terms of the effects of tidal forces (or of spacetime curvature) on the volume of a small ball of test particles (a dust ball), freely falling after all particles were at rest with respect to each other initially. The possibility to express Einstein's equation this way and some of its ramifications have been enjoyably discussed by Baez and Bunn [Am. J. Phys. 73, 644 (2005)]. Since the formulation avoids the use of tensors, neither advanced tensor calculus nor sophisticated differential geometry are needed in the calculation. The derivation is not lengthy and it has visual appeal, so it may be useful in teaching.

  3. The Neutrino Ball Model of a Quasar

    CERN Document Server

    Manka, R; Karczewska, D

    1993-01-01

    It is suggested that the nonorthodox model of a quasar as a neutrino ball described in terms of the standard model extended by adding right-handed neutrinos and the Majorana scalar field can be presented in order to explain a quasar as a body of weak interacting neutrinos. Neutrino interaction with the scalar Majorana field violates the lepton number and produces the mass splitting of the neutrino due to the sea-saw mechanism. In this model a quasar is an object which appears in the result of the first order cosmological phase transition. In this interpretation a quasar may be regarded as a ball filled with Dirac neutrinos and can be treated as a remnant of phase transition with unbroken global lepton symmetry. In this paper we study the macroscopic parameters of such a configuration. In the result the mass-radius curve M(R) for the quasar is obtained.

  4. 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...

  5. 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,...

  6. 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.

  7. 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.

  8. The development of a bearing spectral analyzer and algorithms to detect turbopump bearing wear from deflectometer and strain gage data

    Science.gov (United States)

    Martinez, Carol L.

    1992-07-01

    Over the last several years, Rocketdyne has actively developed condition and health monitoring techniques and their elements for rocket engine components, specifically high pressure turbopumps. Of key interest is the development of bearing signature analysis systems for real-time monitoring of the cryogen-cooled turbopump shaft bearings, which spin at speeds up to 36,000 RPM. These system elements include advanced bearing vibration sensors, signal processing techniques, wear mode algorithms, and integrated control software. Results of development efforts in the areas of signal processing and wear mode identification and quantification algorithms based on strain gage and deflectometer data are presented. Wear modes investigated include: inner race wear, cage pocket wear, outer race wear, differential ball wear, cracked inner race, and nominal wear.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. ANN based Performance Evaluation of BDI for Condition Monitoring of Induction Motor Bearings

    Science.gov (United States)

    Patel, Raj Kumar; Giri, V. K.

    2016-07-01

    One of the critical parts in rotating machines is bearings and most of the failure arises from the defective bearings. Bearing failure leads to failure of a machine and the unpredicted productivity loss in the performance. Therefore, bearing fault detection and prognosis is an integral part of the preventive maintenance procedures. In this paper vibration signal for four conditions of a deep groove ball bearing; normal (N), inner race defect (IRD), ball defect (BD) and outer race defect (ORD) were acquired from a customized bearing test rig, under four different conditions and three different fault sizes. Two approaches have been opted for statistical feature extraction from the vibration signal. In the first approach, raw signal is used for statistical feature extraction and in the second approach statistical features extracted are based on bearing damage index (BDI). The proposed BDI technique uses wavelet packet node energy coefficients analysis method. Both the features are used as inputs to an ANN classifier to evaluate its performance. A comparison of ANN performance is made based on raw vibration data and data chosen by using BDI. The ANN performance has been found to be fairly higher when BDI based signals were used as inputs to the classifier.

  14. 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.

  15. Dynamics Modeling and Analysis of Local Fault of Rolling Element Bearing

    Directory of Open Access Journals (Sweden)

    Lingli Cui

    2015-01-01

    Full Text Available This paper presents a nonlinear vibration model of rolling element bearings with 5 degrees of freedom based on Hertz contact theory and relevant bearing knowledge of kinematics and dynamics. The slipping of ball, oil film stiffness, and the nonlinear time-varying stiffness of the bearing are taken into consideration in the model proposed here. The single-point local fault model of rolling element bearing is introduced into the nonlinear model with 5 degrees of freedom according to the loss of the contact deformation of ball when it rolls into and out of the local fault location. The functions of spall depth corresponding to defects of different shapes are discussed separately in this paper. Then the ode solver in Matlab is adopted to perform a numerical solution on the nonlinear vibration model to simulate the vibration response of the rolling elements bearings with local fault. The simulation signals analysis results show a similar behavior and pattern to that observed in the processed experimental signals of rolling element bearings in both time domain and frequency domain which validated the nonlinear vibration model proposed here to generate typical rolling element bearings local fault signals for possible and effective fault diagnostic algorithms research.

  16. 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.

  17. 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 setti...

  18. 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.

  19. 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.

  20. 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.

  1. AN INNOVATIVE METHOD FOR FORMING BALLS FROM SCRAP RAIL HEADS

    OpenAIRE

    Zbigniew Pater; Janusz Tomczak; Tomasz Bulzak

    2016-01-01

    The paper describes a new method for forming grinding media balls from scrap rail heads. This forming method involves the following operations: cutting the rail head to the desired length combined with lateral pressing of the produced workpiece; flashless die forging and sizing of balls in a helical impression. The proposed method was verified by numerical simulation which involved the modeling of a forming process for producing 80 mm diameter balls. As a result of the modeling, it was possib...

  2. Interpolating sliding mode observer for a ball and beam system

    Science.gov (United States)

    Luai Hammadih, Mohammad; Hosani, Khalifa Al; Boiko, Igor

    2016-09-01

    A principle of interpolating sliding mode observer is introduced in this paper. The observer incorporates multiple linear observers through interpolation of multiple estimates, which is treated as a type of adaptation. The principle is then applied to the ball and beam system for observation of the slope of the beam from the measurement of the ball position. The linearised model of the ball and beam system using multiple linearisation points is developed. The observer dynamics implemented in Matlab/Simulink Real Time Workshop environment. Experiments conducted on the ball and beam experimental setup demonstrate excellent performance of the designed novel interpolating (adaptive) observer.

  3. 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.

  4. 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...

  5. 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

  6. 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.

  7. 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)

  8. 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

  9. Observation of Lightning Ball (Ball Lightning): A new phenomenological description of the phenomenon

    CERN Document Server

    Tar, Domokos

    2009-01-01

    The author (physicist)has observed the very strange,beautiful and frightening Lightning Ball (LB). He has never forgotten this phenomenon. During his working life he could not devote himself to the problem of LB-formation.Only two years ago as he has been reading different unbelievable models of LB-formation, he decided to work on this problem. By studying the literature and the crucial points of his observation the author succeeded in creating a completely new model of Lightning Ball(LB) and Ball Lightning(BL)-formation based on the symmetry breaking of the hydrodynamic vortex ring.This agrees fully with the observation and overcomes the shortcomings of current models of LB formation. This model provides answers to the questions: Why are LBs so rarely observed,why do BLs in rare cases have such a high energy and how can we generate LB in the laboratory? Moreover the author differentiates between LB and BL, the latter having a high energy and occuring in 5 % of the observations. Keywords: ball lightning, hydr...

  10. 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...

  11. 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

  12. Memory in random bouncing ball dynamics

    CERN Document Server

    Zouabi, C; Perret-Liaudet, J

    2016-01-01

    The bouncing of an inelastic ball on a vibrating plate is a popular model used in various fields, from granular gases to nanometer-sized mechanical contacts. For random plate motion, so far, the model has been studied using Poincar{\\'e} maps in which the excitation by the plate at successive bounces is assumed to be a discrete Markovian (memoryless) process. Here, we investigate numerically the behaviour of the model for continuous random excitations with tunable correlation time. We show that the system's dynamics are controlled by the ratio of the Markovian mean flight time of the ball and the mean time between successive peaks in the motion of the exciting plate. When this ratio, which depends on the bandwidth of the excitation signal, exceeds a certain value, the Markovian approach is appropriate; below, memory of preceding excitations arises, leading to a significant decrease of the jump duration; at the smallest values of the ratio, chattering occurs. Overall, our results open the way for uses of the mo...

  13. 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.

  14. 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.

  15. 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...

  16. 76 FR 798 - Ball Bearings From Japan and the United Kingdom

    Science.gov (United States)

    2011-01-06

    ... proceeding and rules of general application, consult the Commission's Rules of Practice and Procedure, part... determination by March 1, 2011. Under the remand schedule ordered by the Court, Plaintiffs, Plaintiff... of the Commission's rules; any submissions that contain BPI must also conform with the...

  17. 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)....

  18. 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...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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,…

  5. 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…

  6. 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,…

  7. [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

  8. 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…

  9. Exact solutions, energy, and charge of stable Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Marques, M.A. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2016-05-15

    In this work we deal with nontopological solutions of the Q-ball type in two spacetime dimensions. We study models of current interest, described by a Higgs-like and other, similar potentials which unveil the presence of exact solutions. We use the analytic results to investigate how to control the energy and charge to make the Q-balls stable. (orig.)

  10. DUAL BASES FOR A NEW FAMILY OF GENERALIZED BALL BASES

    Institute of Scientific and Technical Information of China (English)

    Hong-yiWu

    2004-01-01

    This paper presents the dual bases for a new family of generalized Ball curves with a position parameter K, which includes the Bezier curve, generalized Said-Ball curve and some intermediate curves. Using the dual bases, the relative Marsden identity, conversion formulas of bases and control points of various curves are obtained.

  11. 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)

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. Effectiveness during ball screens in elite basketball games.

    Science.gov (United States)

    Gómez, Miguel-Ángel; Battaglia, Otavio; Lorenzo, Alberto; Lorenzo, Jorge; Jiménez, Sergio; Sampaio, Jaime

    2015-01-01

    Ball screens are one of the most frequently used tactical behaviour in elite basketball games. The aim of the present study was to identify their predictors of success related to time, space, players, and tasks performed. The sample was composed of 818 ball screens corresponding to 20 close games (mean differences in score of 3.1 ± 0.8 points) randomly selected from the playoff games of the Spanish Basketball League (2008-2011). Classification tree analysis (CHAID) was used to analyse which variable or combination of variables, better predicts effectiveness during ball screens. The main results allowed identifying interactions with dribbler actions after the screen and the orientation of the screen on the ball. The results showed no interaction with game quarter and quarter minute temporal-related variables in both analyses. The present findings allow improving coaches' strategic plans that involve selecting the most appropriate offensive approach when performing ball screens.

  17. 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.

  18. 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.

  19. Surface-gradient cross-linked polyethylene acetabular cups: oxidation resistance and wear against smooth and rough femoral balls.

    Science.gov (United States)

    Shen, Fu-Wen; McKellop, Harry

    2005-01-01

    Two methods were developed and evaluated for cross-linking the bearing surface of a polyethylene acetabular cup to a limited depth, in order to improve its resistance to wear without degrading the mechanical properties of the bulk of the component. In the first method, low-energy electron beams were used to cross-link only the bearing surface of the cups to a maximum depth of about 2 mm. The cups then were annealed at 100 degrees C in vacuum for 3 or 6 days to reduce the residual free radicals, and the resultant resistance to oxidation was compared by artificially aging the cups at 80 degrees C in air. Chemically cross-linked surface layers were produced by coating the bearing surfaces of the cups with a thin layer of polyethylene powder mixed with 1% weight peroxide, and compressing them at 6.9 MPa (1000 psi) and 170 degrees C. This resulted in a cross-linked surface layer that extended about 3 mm deep, with a gradual transition to conventional (noncross-linked) polyethylene in the bulk of the implant. In hip simulator wear tests with highly polished (implant quality) femoral balls, both types of surface cross-linking were found to improve markedly the wear resistance of the acetabular cups. In tests with roughened femoral balls, the wear rates were much higher and were comparable to those obtained with similarly roughened balls against noncross-linked polyethylene cups in a previous study, indicating that the full benefit of cross-linking may not be realized under conditions of severe third-body abrasion. Nevertheless, these results show a promising approach for optimizing the wear resistance and the bulk mechanical properties of polyethylene components in total joint arthroplasty.

  20. 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...

  1. 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.

  2. 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...

  3. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  4. 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.

  5. 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.

  6. 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.

  7. Prognosticating fault development rate in wind turbine generator bearings using local trend models

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Palou, Jonel; Sweeney, Christian Walsted;

    2016-01-01

    the signal energy between 10Hz to 1000Hz is utilized as feature to characterize the severity of developing bearing faults. Furthermore, local trend models are employed to predict the progression of bearing defects from a vibration standpoint in accordance with the limits suggested in ISO 10816. Predictions......Generator bearing defects, e.g. ball, inner and outer race defects, are ranked among the most frequent mechanical failures encountered in wind turbines. Diagnosis and prognosis of bearing faults can be successfully implemented using vibration based condition monitoring systems, where tracking...... of vibration trends from multi-megawatt wind turbine generators are presented, showing the effectiveness of the suggested approach on the calculation of the RUL and fault progression rate....

  8. 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.

  9. Synthesis of porous carbon balls from spherical colloidal crystal templates.

    Science.gov (United States)

    Kim, Youngchan; Cho, Chang-Yeol; Kang, Ji-Hwan; Cho, Young-Sang; Moon, Jun Hyuk

    2012-07-17

    Spherical inverse opal (IO) porous carbon was produced utilizing silica colloidal crystal spheres as templates. The spherical colloidal crystals were obtained through the self-assembly of monodisperse particles inside an emulsion droplet with confined geometry. The templates were inverted using a carbon precursor, phenol-formaldehyde (PF) resol. We demonstrated a two-step synthesis involving the subsequent infiltration of the PF resol precursor into the spherical colloidal crystal template and a one-step synthesis using a silica colloidal solution containing dissolved PF resol. In the former case, the sizes of the IO carbon balls were controlled by the size of the colloidal crystal templates, and diameters of a few micrometers up to 50 μm were obtained. The average diameter of the macropores created by the silica particles was 230 nm. Moreover, meso-/macroporous IO carbon balls were created using block-copolymer templates in the PF resol. In the one-step synthesis, the concentration of PF resol in the colloidal solution controlled the diameter of the IO carbon balls. IO balls smaller than 3 μm were obtained from the direct addition of 5% PF resol. The one-step synthesis produced rather irregular porous structures reflecting the less ordered crystallization processes inside the spherical colloidal crystals. Nitrogen adsorption and cyclic voltammetry measurements were conducted to measure the specific area and electroactive surface area of the IO carbon balls. The specific area of the mesopores-incorporated IO carbon balls was 1.3 times higher than that of bare IO carbon balls. Accordingly, the meso-/macroporous porous carbon balls exhibited higher electrocatalytic properties than the macroporous carbon balls.

  10. 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.

  11. The Little Bear

    Institute of Scientific and Technical Information of China (English)

    林战峰; 乐伟国

    2007-01-01

    @@ 一、故事内容 A little bear has a magic stick.It can make his wishes come true. One day,the little bear is walking in the forest.He sees a bird.It is flying in the sky.It has two beautiful wings."I want two beautiful wings.I wish I can fly like a bird,"he says to the magic stick.Two beautiful wings come out from his back and he can fly like a bird now.He is very happy.

  12. 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 ...

  13. [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

  14. [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.

  15. 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

  16. Screw compressors and their reliability. Oil and bearing problems with the example of screw compressors in refrigeration engineering. Schraubenverdichter und ihre Zuverlaessigkeit. Oel- und Lagerungsproblematik am Beispiel von Schraubenverdichtern in der Kaeltetechnik

    Energy Technology Data Exchange (ETDEWEB)

    Hesse, U. (Forschungszentrum fuer Kaeltetechnik und Waermepumpen GmbH, Hannover (Germany)); Rinne, F.; Kruse, H. (Hannover Univ. (Germany). Inst. fuer Kaeltetechnik und Angewandte Waermetechnik)

    1991-11-01

    Screw compressors are due to their simple structure with few moving parts reliable refrigeration compressors. But a pre-requisite for this is that the lubricant problem is taken into consideration. Otherwise damage results, here above all bearings are affected. As the viscosity of the working fluid is particularly important above all synthetic refrigerator oils are used. The described measuring method for bearing load measurements can also be applied to other types of compressors. A measurement should be carried out especially in case of new constructions in order to face bearing problems at an early stage. Until now bearing loads of rolling bearings e.g. in case of bearing damage have been calculated with the running traces by ball bearing manufacturers. Load-sensing bearings are very advantageous as they can be directly exchanged with the series bearings without great modifications and as actual loads are very precisely measured. (orig.).

  17. 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.

  18. Silver Bear for Screenplay

    Institute of Scientific and Technical Information of China (English)

    LIU YUNYUN

    2010-01-01

    @@ Chinese director Wang Quan'an won the Silver Bear Prize at the 60th Berlin International Film Festival that lasted during February 11 to 21 tor the best screenplay for his movie Apart Together.The film also opened the festival.

  19. Hybrid superconductor magnet bearings

    Science.gov (United States)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  4. 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.

  5. Confining rigid balls by mimicking quadrupole ion trapping

    CERN Document Server

    Fan, Wenkai; Wang, Sihui; Zhou, Huijun

    2016-01-01

    The rotating saddle not only is an interesting system that is able to trap a ball near its saddle point, but can also intuitively illustrate the operating principles of quadrupole ion traps in modern physics. Unlike the conventional models based on the mass-point approximation, we study the stability of a ball in a rotating-saddle trap using rigid-body dynamics. The stabilization condition of the system is theoretically derived and subsequently verified by experiments. The results are compared with the previous mass-point model, giving large discrepancy as the curvature of the ball is comparable to that of the saddle. We also point out that the spin angular velocity of the ball is analogous to the cyclotron frequency of ions in an external magnetic field utilized in many prevailing ion-trapping schemes.

  6. AN INNOVATIVE METHOD FOR FORMING BALLS FROM SCRAP RAIL HEADS

    Directory of Open Access Journals (Sweden)

    Zbigniew Pater

    2016-09-01

    Full Text Available The paper describes a new method for forming grinding media balls from scrap rail heads. This forming method involves the following operations: cutting the rail head to the desired length combined with lateral pressing of the produced workpiece; flashless die forging and sizing of balls in a helical impression. The proposed method was verified by numerical simulation which involved the modeling of a forming process for producing 80 mm diameter balls. As a result of the modeling, it was possible to examine the changes in the workpiece shape during each forming operation, the variations in loads and torques, as well as the distribution of temperatures enabling performing another forming operation, i.e. quenching. The results confirm that the designed method can be used to produce balls.

  7. Transversal stability of the bouncing ball on a concave surface

    Science.gov (United States)

    Chastaing, J.-Y.; Pillet, G.; Taberlet, N.; Géminard, J.-C.

    2015-05-01

    A ball bouncing repeatedly on a vertically vibrating surface constitutes the famous "bouncing ball" problem, a nonlinear system used in the 1980s, and still in use nowadays, to illustrate the route to chaos by period doubling. In experiments, in order to avoid the ball escape that would be inevitable with a flat surface, a concave lens is often used to limit the horizontal motion. However, we observe experimentally that the system is not stable. The ball departs from the system axis and exhibits a pendular motion in the permanent regime. We propose theoretical arguments to account for the decrease of the growth rate and of the asymptotic-size of the trajectory when the frequency of the vibration is increased. The instability is very sensitive to the physics of the contacts, which makes it a potentially interesting way to study the collisions rules, or to test the laws used in numerical studies of granular matter.

  8. 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.

  9. 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.

  10. 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.

  11. 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.)

  12. New electrosurgical ball electrode with nonstick properties

    Science.gov (United States)

    Rondinone, Joseph; Brassell, James; Miller, Scott A., III; Thorne, Jonathan O.; Rondinone, David M.; Safabash, Jason; Vega, Felix

    1998-04-01

    A new electrosurgical ball electrode (SilverBulletTM) has been developed for applying radiofrequency (RF) energy to fuse biological and other materials to tissue surfaces. Specifically, the electrode was developed for use in conjunction with the Fusion Medical Technologies, Inc. gelatin patch (RapiSealTM) for use in pulmonary surgery to seal air leaks, and in solid abdominal organ surgeries to provide hemostatic tamponade. The new electrode allows for the application of RF energy in contact mode without the problems of the electrode sticking to the gelatin patch or the underlying tissue. Designed for use with commercially available electrosurgical handpieces, the electrode consists of a stainless steel connector that fits into the hand- piece, and an electrode assembly made from silver that includes a shank region, and a tip extension extending distally from the shank region. The distal tip of the tip extension is rounded and has a length of about 10 mm. The uniqueness of this electrode is the shank region which has a cross sectional area that is larger than the tip extension. The shank region acts as a heat sink to draw away heat from the tip extension while the tip extension itself remains sufficiently small to access desired target sites and display the desired energy transfer properties. In addition to the physical design, the use of silver as the core element provides a material with high electrical and thermal conductivities. The bulk of the electrode is appropriately insulated.

  13. A lightweight method for computing ball spin in real time

    OpenAIRE

    Cristina, Federico; Dapoto, Sebastián H.; Russo, Claudia Cecilia

    2007-01-01

    The present paper poses a new method for computing the rotation of a ball in sport training situations, when the ball is approaching the goal line. The proposed method significantly reduces the hardware requirements associated to the capture, as well as the computational complexity necessary to obtain the results. The system's objective is to improve the player's technique and training methodology, and it is treated within the scope of the Institute's research line on signal and image process...

  14. 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...

  15. 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.

  16. On the quantum stability of Q-balls

    CERN Document Server

    Tranberg, Anders

    2014-01-01

    We consider the evolution and decay of Q-balls under the influence of quantum fluctuations. We argue that the most important effect of quantum fluctuations is the modification of the effective potential in which the Q-ball evolves. This effect is in addition to spontaneous decay into elementary particle excitations and decay into smaller Q-balls considered in the literature, which like most tunnelling processes are likely to be strongly suppressed. We exemplify the effect of quantum fluctuations in a particular model potential (quadratic + quartic + sextic couplings), where we implement the inhomogeneous Hartree approximation of quantum dynamics and solve for the evolution of Q-balls in 3+1 dimensions. We find that the stability range as a function of angular velocity $\\omega$ is modified significantly compared to the classical case, so that small-$\\omega$ Q-balls are less stable than in the classical limit, and large-$\\omega$ Q-balls are more stable. This can be understood qualitatively in a simple way.

  17. On the quantum stability of Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Tranberg, Anders [Faculty of Science and Technology, University of Stavanger,4036 Stavanger (Norway); Weir, David J. [Department of Physics and Helsinki Institute of Physics,PL 64 (Gustaf Hällströmin katu 2), FI-00014 University of Helsinki (Finland)

    2014-04-30

    We consider the evolution and decay of Q-balls under the influence of quantum fluctuations. We argue that the most important effect resulting from these fluctuations is the modification of the effective potential in which the Q-ball evolves. This is in addition to spontaneous decay into elementary particle excitations and fission into smaller Q-balls previously considered in the literature, which — like most tunnelling processes — are likely to be strongly suppressed. We illustrate the effect of quantum fluctuations in a particular model ϕ{sup 6} potential, for which we implement the inhomogeneous Hartree approximation to quantum dynamics and solve for the evolution of Q-balls in 3+1 dimensions. We find that the stability range as a function of (field space) angular velocity ω is modified significantly compared to the classical case, so that small-ω Q-balls are less stable than in the classical limit, and large-ω Q-balls are more stable. This can be understood qualitatively in a simple way.

  18. On the quantum stability of Q-balls

    Science.gov (United States)

    Tranberg, Anders; Weir, David J.

    2014-04-01

    We consider the evolution and decay of Q-balls under the influence of quantum fluctuations. We argue that the most important effect resulting from these fluctuations is the modification of the effective potential in which the Q-ball evolves. This is in addition to spontaneous decay into elementary particle excitations and fission into smaller Q-balls previously considered in the literature, which — like most tunnelling processes — are likely to be strongly suppressed. We illustrate the effect of quantum fluctuations in a particular model ϕ 6 potential, for which we implement the inhomogeneous Hartree approximation to quantum dynamics and solve for the evolution of Q-balls in 3 + 1 dimensions. We find that the stability range as a function of (field space) angular velocity ω is modified significantly compared to the classical case, so that small- ω Q-balls are less stable than in the classical limit, and large- ω Q-balls are more stable. This can be understood qualitatively in a simple way.

  19. Magnetic bearings grow more attractive

    Science.gov (United States)

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  20. 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...

  1. Supported Load Condition and Life Analysis for Momentum Flywheel Bearing%动量飞轮轴承的受载情况及寿命分析

    Institute of Scientific and Technical Information of China (English)

    臧稳通; 李建华

    2000-01-01

    The momentum flywheel is a key operating mechanism of space aircraft.Under the space environment,it is vital for aircraft to keep the optimum operating state and long life.The paper analyzes loaded condition of momentum flywheel and life of angular contact ball bearing with preload.

  2. 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...

  3. Passive magnetic bearing system

    Science.gov (United States)

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  4. 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.

  5. Magnetic bearing and motor

    Science.gov (United States)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  6. 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

  7. 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.

  8. Magnetic translator bearings

    Science.gov (United States)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  9. 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.

  10. 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.

  11. THE BEHAVIOURAL REACTION OF WEANERS TO HANGING TOYS: WOODEN BALL AND AROMATIZED WOODEN BALL – WAY TO REDUCE AGGRESSION AFTER MIXING

    Directory of Open Access Journals (Sweden)

    Jacek NOWICKI

    2008-05-01

    Full Text Available The behaviour of weaners after mixing housed in pens equipped with hanging wooden ball, aromatized with vanilla fluid hanging wooden ball and without enrichment was evaluated. It was found that both enrichments reduced aggression, however the most interesting for weaners was the aromatized wooden ball.

  12. Design and application on experimental platform for high-speed bearing with grease lubrication

    Directory of Open Access Journals (Sweden)

    He Qiang

    2015-12-01

    Full Text Available The experimental platform for high-speed grease is an important tool for research and development of high-speed motorized spindle with grease lubrication. In this article, the experimental platform for high-speed grease is designed and manufactured which consists of the drive system, the test portion, the loading system, the lubrication system, the control system, and so on. In the meantime, the high-speed angular contact ceramic ball bearings B7005C/HQ1P4 as the research object are tested and contrasted in the grease lubrication and oil mist lubrication. The experimental platform performance is validated by contrast experiment, and the high-speed lubricated bearing performance is also studied especially in the relationship among the rotating speed,load and temperature rise. The results show that the experimental platform works steadily, accurate, and reliable in the experimental testing. And the grease lubrication ceramic ball bearings B7005C/HQ1P4 can be used in high-speed motorized spindle in the circular water cooling conditions when the rotating speed is lower than 40,000 r/min or the DN value (the value of the bearing diameter times the rotating speed is lower than the 1.44 × 106 mm r/min. Grease lubrication instead of oil mist lubrication under high-speed rotating will simplify the structure design of the high-speed motorized spindle and reduce the pollution to the environment.

  13. 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.

  14. Effect of Bearing Cleaning on Long Term Bearing Life

    Science.gov (United States)

    Jett, Tim; Thom, R. L.

    1999-01-01

    For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  4. Effects of turbulence on the drag force on a golf ball

    Science.gov (United States)

    Cross, Rod

    2016-09-01

    Measurements are presented of the drag force on a golf ball dropped vertically into a tank of water. As observed previously in air, the drag coefficient drops sharply when the flow becomes turbulent. The experiment would be suitable for undergraduate students since it can be undertaken at low ball speeds and since the effects of turbulence are easily observed on video film. A modified golf ball was used to show how a ball with a smooth and a rough side, such as a cricket ball, is subject to a side force when the ball surface itself is asymmetrical in the transverse direction.

  5. Nanoprecipitation in bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, A.T.W. [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2011-11-15

    {theta}-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The {theta}-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

  6. 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)

  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. 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.

  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. On the 1-density of Unit Ball Covering

    CERN Document Server

    Zhu, Binhai

    2007-01-01

    Motivated by modern applications like image processing and wireless sensor networks, we consider a variation of the famous Kepler Conjecture. Given any infinite set of unit balls covering the whole space, we want to know the optimal (lim sup) density of the volume which is covered by exactly one ball (i.e., the maximum such density over all unit ball covers, called the {\\em optimal 1-density} and denoted as $\\delta_d$, where $d$ is the dimension of the Euclidean space). We prove that in 2D the optimal 1-density $\\delta_2=(3\\sqrt(3)-\\pi)/\\pi \\approx 0.6538$, which is achieved through a hexagonal covering. In 3D, we show numerically that the dodecahedral covering ({\\em dc}) achieves a 1-density $\\delta_3(dc)\\approx 0.315$. We conjecture that this is in fact the optimal 1-density in 3D.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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...

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

    Science.gov (United States)

    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 degrees; and increases the magnitude of the distance sensing signal through water. Also presented is a cutting function with an improved ergonomic design. PMID:24224076

  18. 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.

  19. 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.

  20. 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.

  1. 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 ...

  2. 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

  3. 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

  4. 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.

  5. 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...

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Unifying representation of Bézier curve and two kinds of generalized ball curves

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiaolin; WANG Zhihua

    2012-01-01

    This paper presents a new basis, the WSB basis, which unifies the Bemstein basis, Wang-Ball basis and Said-Ball basis, and therefore the Bézier curve, Wang-Ball curve and Said-Ball curve are the special cases of the WSB curve based on the WSB basis In addition, the relative degree elevation formula, recursive algorithm and conversion formula between the WSB basis and the Bern- stein basis are given.

  11. The winner in the race of bearing surface

    Directory of Open Access Journals (Sweden)

    Xiao-yang HU

    2011-08-01

    Full Text Available There are no absolute ’winners’ in this ’race of bearing surface’.Since the mechanical performance of the modern bearing surface used in total hip joint manufacture is satisfactory,it is necessary to take their advantage respectively and treat each patient independently.Patient satisfaction,quality of life,and radiographic analysis should also be considered.Specifically,high crosslinked UHMWPE cup articulating with CoCr alloy and the alternative of ceramic ball are surviving for almost thirty years because of their high wear resistance,no toxicity and comparably low cost.They are more suitable for the patients who are not very young and less active and ask for a relatively lower physical and financial condition of patients.For patients articulating with MOM,they benefit from larger sized heads and low wear and friction,which would produce more stability for more active patients.However,one should be aware of the metal ions released in serum as well as in urine.Therefore,MOM is not fit for patients who are pregnant or suffer from renal insufficiency etc.A random kidney function test should be performed before MOM surgery.Last but not least,the COC bearing surface has all the superiorities mentioned above but with a risk of fracture and a rarely audible squeaking.The fairly high cost makes it not a choice for everyone,but it could be a lifelong choice for younger patients with a lot of high impact activities.More in vitro and long term in vivo studies are needed to prove longer lasting effects to improve bearing surfaces.

  12. Temporomandibular joint dislocation and deafness from a cricket ball injury.

    Science.gov (United States)

    Murthy, P; Bandasson, C; Dhillon, R S

    1994-05-01

    Cricket is a national sport in some countries and can be potentially hazardous. We report an incident of a cricket ball impact to the chin, which resulted in posterior dislocation of both temporomandibular joints and bilateral mixed deafness. There appear to be no similar case reports in the literature.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. On the isoperimetric rigidity of extrinsic minimal balls

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, V.

    2003-01-01

    We consider an m-dimensional minimal submanifold P and a metric R-sphere in the Euclidean space R-n. If the sphere has its center p on P, then it will cut out a well defined connected component of P which contains this center point. We call this connected component an extrinsic minimal R-ball of ...

  20. 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.

  1. 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.

  2. Weighted Plancherel formula on unit ball in R

    Institute of Scientific and Technical Information of China (English)

    刘建明; 郑维行

    1996-01-01

    Let / be a function on the unit ball of Rn. For , the action T of SO0 (1, n) on f isdefined by .The invariant Laplacian corresponding to T is calculated, and a family of its eigenfunctions is found out. Then the corresponding Fourier transform is defined and the inversion formula and Plancherel formula are obtained.

  3. Astroblaster--A Fascinating Game of Multi-Ball Collisions

    Science.gov (United States)

    Kires, Marian

    2009-01-01

    Multi-ball collisions inside the Astroblaster toy are explained from the conservation of momentum point of view. The important role of the coefficient of restitution is demonstrated in ideal and real cases. Real experimental results with the simple toy can be compared with a computer model represented by an interactive Java applet. (Contains 1…

  4. 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.

  5. Systematization of problems on ball estimates of a convex compactum

    Science.gov (United States)

    Dudov, S. I.

    2015-09-01

    We consider a class of finite-dimensional problems on the estimation of a convex compactum by a ball of an arbitrary norm in the form of extremal problems whose goal function is expressed via the function of the distance to the farthest point of the compactum and the function of the distance to the nearest point of the compactum or its complement. Special attention is devoted to the problem of estimating (approximating) a convex compactum by a ball of fixed radius in the Hausdorff metric. It is proved that this problem plays the role of the canonical problem: solutions of any problem in the class under consideration can be expressed via solutions of this problem for certain values of the radius. Based on studying and using the properties of solutions of this canonical problem, we obtain ranges of values of the radius in which the canonical problem expresses solutions of the problems on inscribed and circumscribed balls, the problem of uniform estimate by a ball in the Hausdorff metric, the problem of asphericity of a convex body, the problems of spherical shells of the least thickness and of the least volume for the boundary of a convex body. This makes it possible to arrange the problems in increasing order of the corresponding values of the radius. Bibliography: 34 titles.

  6. The spectacle of the ball python (Python regius)

    DEFF Research Database (Denmark)

    Da Silva, Mari-Ann O; 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...

  7. Eric Cantona: Fußball-Ikone der modernen Medienwelt

    Directory of Open Access Journals (Sweden)

    Martin Wassermair

    2010-03-01

    Full Text Available In Unterhaltungsindustrie und Massenmedien nimmt der Sport eine im wahrsten Sinne des Wortes bewegende Rolle ein. Er ist zugleich Wettkampf-Arena und Wunschmaschine, Werbefläche und Starproduktion. Dass die Erscheinungsformen des Sports in der modernen Medienwelt einer rasanten Dynamik und Wechselbeziehung unterliegen, ist am Beispiel des Massenphänomens Fußballs vielleicht am deutlichsten abzulesen.

  8. 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…

  9. Preparation of iron sulphides by high energy ball milling

    DEFF Research Database (Denmark)

    Lin, R.; Jiang, Jianzhong; Larsen, R.K.;

    1998-01-01

    The reaction of a powder mixture consisting of 50 a.% Fe and 50 a.% S during high energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. After around 19 h of milling FeS2 and FeS havebeen formed. By further milling the FeS compound becomes dominating and only Fe...

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. Superconducting bearings for flywheel applications

    OpenAIRE

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings in flywheels.

  17. What about the Javan Bear?

    NARCIS (Netherlands)

    Jentink, F.A.

    1898-01-01

    The other day I read in a dutch popular periodical a paper dealing with the different species of Bears and their geographical distribution. To my great surprise the Malayan Bear was mentioned from Java: the locality Java being quite new to me I wrote to the author of that paper and asked him some in

  18. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  19. Effect of aging on rheology of ball clay suspensions

    Science.gov (United States)

    Tonthai, Tienchai

    2002-01-01

    The behaviors of clay-water suspensions such as deflocculation or rheological properties are not constant but change with time. Aging has been recognized for changing the rheological properties of clay suspensions. This work provided information about the effects of the moisture contents in ball clay lumps and clay air exposure time on their processability. Dynamic oscillatory rheometry using a vane-in-cup geometry was used to characterize the rheological behavior of ball clay suspensions in terms of elastic modulus, viscous modulus and yield stress as a function of aging time. A light scattering size analyzer was used to examine the agglomerate size distribution of ball clay suspensions which affected the rheological behavior. Soluble ion release (both cations and anions) in the filtrate of suspensions was measured by ion chromatography. Low and high lignitic ball clay suspensions were dispersed with sodium silicate (Na2SiO3) or sodium polyacrylate at specific gravity 1.3 and 1.6 in two dispersion states: fully deflocculated (minimum viscosity) and under deflocculated. Suspensions prepared using freshly mined ball clays required more dispersant than suspensions prepared using dry ball clays to achieve minimum viscosity due to a difference in agglomerate size distribution. The agglomerate size distribution of suspensions prepared using dry clays was broader than that of suspensions prepared using freshly mined clays. In suspensions prepared using freshly mined clays, there were many uniformly small agglomerates having loose water inside, while in suspensions prepared using dry clays, the capillary effect and bonding between clay particles resulting from drying broke clay aggregates apart into agglomerate structures composed of a few to many clay particles. For suspensions prepared using dry clays after one day suspension aging, the elastic modulus and yield stress decreased due to the change in agglomerate size distribution of suspensions but increased for

  20. Rolling Motion of a Ball Spinning about a Near-Vertical Axis

    Science.gov (United States)

    Cross, Rod

    2012-01-01

    A ball that is projected forward without spin on a horizontal surface will slide for a short distance before it starts rolling. Sliding friction acts to decrease the translation speed v and it acts to increase the rotation speed [omega]. When v = R[omega], where R is the ball radius, the ball will start rolling and the friction force drops almost…

  1. The Maya ball game. Comparison of the physical load with modern ball games.

    Science.gov (United States)

    Blümchen, Gerhard

    2009-01-01

    The Maya ball game (MBG) originated more than 3,000 years ago. As best as is now known from archaeological and iconographical sources as well as the structure of the sport courts, this was a very physically taxing and important part of Mayan culture. The objective of this paper was to determine the physical load on those who participated in MBG as best as could be done from present perspectives. The load appears to be similar to that observed in soccer-tennis, in which heart rate rises to 140-160 beats/min and systolic blood pressure to 150-170 mm Hg. This is considered a light-to-moderate workload (4.5-5.5 metabolic equivalents) comparable to intensities reached in baseball, cycling (10 km/h), cross-country skiing (7 km/h), tournament dancing, swimming (2 km/h), doubles tennis and hiking (7 km/h). Thus, the cardiovascular demands of popular sports seem to have remained relatively similar through several millennia. PMID:19246899

  2. Geophagy by yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  3. The Statement of Design and Application Questions for the Gyroscope with a Gas-dynamic Suspension of Ball Rotor in the Navigation Support Drilling System

    Science.gov (United States)

    Golikov, A. N.; Ignatovskaya, A. A.

    2016-01-01

    The general issues of creation the inertial navigation system are considered. Analysis of the possible implementation of the gyroscope with a gas-dynamic suspension of ball rotor for using it as a sensor in the information and measuring complex is provided. The permissible layout construction is proposed. The software system variants for the mathematical modelling of the main gas-dynamic bearing characteristics are considered. Mathematical modelling is essential to extend and optimize the design parameters of the developed gyroscopic construction. Some results of modelling, theoretical evaluation and preliminary experimental studies are summarized.

  4. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

    OpenAIRE

    Cahill, J.; Stirling, I.; Kistler, L.; Salamzade, R.; Ersmark, E.; Fulton, T.; Stiller, M.; Green, R.; Shapiro, B.

    2015-01-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear...

  5. Historiografia del “Ball de Torrent”: De la moixiganga barroca al quadre de balls populars valencians (1692-1929

    Directory of Open Access Journals (Sweden)

    Raül Sanchis Francés

    2013-06-01

    Full Text Available Resum: El Ball de Torrent és una moixiganga dramàtica popular escenificada a la ciutat de València i altres indrets del País Valencià des de finals del segle XVII fins a principis del segle XX. Estava organitzada per agrupacions gremials, juntes d’hospitals o clavaris de festes i protagonitzada per personatges agrupats en comparses que representaven una paròdia sobre les relacions entre les estructures de poder i les classes populars. Tot i la variabilitat segons el moment històric, es conforma com una mescla de quadres amb danses, música i jocs teatrals. El ball interacciona de diverses formes amb algunes festes valencianes i és, probablement, una de les mostres de teatre de carrer més nostrades i menys estudiades de la València Moderna. En aquest article es realitza una revisió bibliogràfica crítica i una primera anàlisi historiogràfica.Paraules clau: Ball de Torrent, Dansa i música tradicional, Teatre, Moixiganga, Festa valencianaAbstract: Ball de Torrent (Dance of Torrent is a popular dramatic masquerade staged in Valencia since the late seventeenth century to the early twentieth. It was organized by guilds, hospital managements or festival organizers. The actors were grouped in associations representing a parody on the relationships between power structures and popular classes. Despite the variability depending on the historical period, it consisted of a mixture of episodes or scenes with dance, music and theatre games. Any Festivals in Valencia are connected with the Ball de Torrent. It’s probably one of the most interesting samples of street theatre and studied under of the Modern Valencia. This paper analyses historical sources to review and critique bibliography.Keywords: Dance of Torrent, Traditional Dance and Music, Theatre, Masquerade, Feasts of Valencia

  6. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    Science.gov (United States)

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research.

  7. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    Science.gov (United States)

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research. PMID:27314607

  8. Surge Control of a Centrifugal Compression System by Using a Bouncing Ball

    Institute of Scientific and Technical Information of China (English)

    Yuichiro Asaga; Shimpei Mizuki; Hoshio Tsujita; Shinsuke Ohta

    2008-01-01

    The purpose of this study is to suppress the fluctuations of surge by a simple passive control method. A bouncing ball system with different weight of the balls was tested. As a result, the bouncing ball system suppressed mild surge without the deterioration of the performance characteristics, and moved the initiation point of surge toward the lower flow rate when the steel ball of 15mm outer diameter was used. The present system was effective to suppress the surge and to widen the stable operating range of a centrifugal compressor when the ball was chosen appropriately.

  9. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  10. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  11. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  12. A new principle and device for large aircraft components gaining accurate support by ball joint

    Institute of Scientific and Technical Information of China (English)

    Bao-gui QIU; Jun-xia JIANG; Ying-lin KE

    2011-01-01

    How to obtain an accurate support for large components by ball joint is a key process in aircraft digital assembly. A novel principle and device is developed to solve the problem. Firstly, the working principle of the device is introduced. When three or four displacement sensors installed in the localizer are touched by the ball-head, the spatial relation is calculated between the large aircraft component's ball-head and the localizer's ball-socket. The localizer is driven to achieve a new position by compensation. Relatively, a support revising algorithm is proposed. The localizer's ball-socket approaches the ball-head based on the displacement sensors. According to the points selected from its spherical surface, the coordinates of ball-head spherical center are computed by geometry. Finally, as a typical application, the device is used to conduct a test-fuselage's ball-head into a localizer's ball-socket. Positional deviations of the spherical centers between the ball-head and the ball-socket in the x, y, and z directions are all controlled within ±0.05 mm under various working conditions. The results of the experiments show that the device has the characteristics of high precision, excellent stability, strong operability, and great potential to be applied widely in the modern aircraft industry.

  13. The head tracks and gaze predicts: how the world's best batters hit a ball.

    Directory of Open Access Journals (Sweden)

    David L Mann

    Full Text Available Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i baseball and cricket batters cannot track the ball because it moves too quickly to be tracked by the eyes, and that consequently (ii batters do not - and possibly cannot - watch the ball at the moment they hit it. However, to date no studies have examined the gaze of truly elite batters. We examined the eye and head movements of two of the world's best cricket batters and found both claims do not apply to these batters. Remarkably, the batters coupled the rotation of their head to the movement of the ball, ensuring the ball remained in a consistent direction relative to their head. To this end, the ball could be followed if the batters simply moved their head and kept their eyes still. Instead of doing so, we show the elite batters used distinctive eye movement strategies, usually relying on two predictive saccades to anticipate (i the location of ball-bounce, and (ii the location of bat-ball contact, ensuring they could direct their gaze towards the ball as they hit it. These specific head and eye movement strategies play important functional roles in contributing towards interceptive expertise.

  14. Trajectory-based ball detection and tracking with aid of homography in broadcast tennis video

    Science.gov (United States)

    Yu, Xinguo; Jiang, Nianjuan; Ang, Ee Luang

    2007-01-01

    Ball-detection-and-tracking in broadcast tennis video (BTV) is a crucial but challenging task in tennis video semantics analysis. Informally, the challenges are due to camera motion and the other causes such as the presence of many ball-like objects and the small size of the tennis ball. The trajectory-based approach proposed by us in our previous papers mainly counteracted the challenges imposed by causes other than camera motion and achieves a good performance. This paper proposes an improved trajectory-based ball detection and tracking algorithm in BTV with the aid of homography, which counteracts the challenges caused by camera motion and bring us multiple new merits. Firstly, it acquires an accurate homography, which transforms each frame into the "standard" frame. Secondly, it achieved higher accuracy of ball identification. Thirdly, it obtains the ball projection position in the real world, instead of ball location in the image. Lastly, it also identifies landing frames and positions of the ball. The experimental results show that the improved algorithm can obtain not only higher accuracy in ball identification and in ball position alike, but also ball landing frames and positions. With the intent of using homography to improve the video-based event detection for smart home we also do some experiments on acquiring the homography for home surveillance video.

  15. Stochastic Resonance algorithms to enhance damage detection in bearing faults

    Directory of Open Access Journals (Sweden)

    Castiglione Roberto

    2015-01-01

    Full Text Available Stochastic Resonance is a phenomenon, studied and mainly exploited in telecommunication, which permits the amplification and detection of weak signals by the assistance of noise. The first papers on this technique are dated early 80 s and were developed to explain the periodically recurrent ice ages. Other applications mainly concern neuroscience, biology, medicine and obviously signal analysis and processing. Recently, some researchers have applied the technique for detecting faults in mechanical systems and bearings. In this paper, we try to better understand the conditions of applicability and which is the best algorithm to be adopted for these purposes. In fact, to get the methodology profitable and efficient to enhance the signal spikes due to fault in rings and balls/rollers of bearings, some parameters have to be properly selected. This is a problem since in system identification this procedure should be as blind as possible. Two algorithms are analysed: the first exploits classical SR with three parameters mutually dependent, while the other uses Woods-Saxon potential, with three parameters yet but holding a different meaning. The comparison of the performances of the two algorithms and the optimal choice of their parameters are the scopes of this paper. Algorithms are tested on simulated and experimental data showing an evident capacity of increasing the signal to noise ratio.

  16. Optimization of residual heat removal pump axial thrust and axial bearing

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, F.

    1996-12-01

    The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

  17. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage.

    Science.gov (United States)

    Yang, Z; Chen, H; Yu, T; Li, B

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage. PMID:27587158

  18. ANN BASED FAULT DIAGNOSIS OF ROLLING ELEMENT BEARING USING TIME-FREQUENCY DOMAIN FEATURE

    Directory of Open Access Journals (Sweden)

    D.H. PANDYA

    2012-06-01

    Full Text Available This paper presents a methodology for an automation of fault diagnosis of ball bearings having localized defects (spalls on the various bearing components. The system uses the wavelet packet decomposition using ‘rbio5.5’ real mother wavelet function for feature extraction from the vibration signal, recorded for various bearing fault conditions. The decomposition level is determined by the sampling frequency and characteristic defect frequency. Maximum energy to minimum Shannon entropy ratio criteria is used for selection of best node of wavelet packet tree. The two features kurtosis and energy are extracted from the wavelet packet coefficient for selected node of WPT. The total 10 data sets at five different speeds corresponding to each bearing condition are recorded for fault classification. Thus, extracted features are used to train and test neural network with multi layer perceptron to classify the rolling element bearing condition as HB, ORD, IRD, BD and CD. The proposedartificial neural network with multi layer perceptron classifier has overall fault classification rate of 97 %.

  19. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

    Science.gov (United States)

    Yang, Z.; Chen, H.; Yu, T.; Li, B.

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  20. Mixed-mu superconducting bearings

    Science.gov (United States)

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.