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Sample records for ab1157 strains bearing

  1. Influence of an aqueous extract of Hypericum perforatum (Hypericin on the survival of Escherichia coli AB1157 and on the electrophoretic mobility of pBSK plasmid DNA Influência de um extrato aquoso de Hypericum perforatum (Hipericina na sobreviência de Escherichia coli AB1157 e na mobilidade eletroforética de DNA plasmidial pBSK

    Sebastião D. Santos-Filho

    2008-09-01

    Full Text Available Hiperico (Hypericum perforatum or St John's worth has been widely used as an herbal medicine to treat depression. Hypericin is the main chemical compound of hiperico. Stannous chloride (SnCl2 is the most used reducing agent in nuclear medicine. The aim of this work was to verify the effect of a hiperico extract on the survival of Escherichia coli AB1157 and on the plasmid DNA topology. Exponentially E. coli AB1157 cultures were incubated with SnCl2 in the presence or absence of hypericin. Aliquots were spread onto Petri dishes containing solidified rich medium, the colonies units were counted after overnight and the survival fraction was calculated. Plasmid DNA samples were incubated with SnCl2 in presence or absence of hypericin extract during 40 minutes, 0.8% agarose gel electrophoresis was performed, the gel was stained with ethidium bromide and the plasmid topological forms (bands were visualized. The results revealed that hiperico extract is neither capable of altering the survival of E. coli cells nor the plasmid DNA topology but it may have protected these cells against the SnCl2 action. The data suggest absence of cytotoxic and genotoxic effects of the aqueous hiperico extract and a protective effect on E. coli cells against the action of SnCl2.Hipérico (Hypericum perforatum or St John's worth tem sido usado como uma planta medicinal para tratar a depressão. Hipericina é o principal componente do hipérico. O cloreto estanoso (SnCl2 é o agente redutor mais utilizado em medicina nuclear. O objetivo desse trabalho foi verificar o efeito de um extrato de hipérico na sobrevivência de Escherichia coli AB1157 e na topologia do DNA plasmidial. Culturas de E. coli AB1157, em fase exponencial, foram incubadas com SnCl2 na presença ou ausência de hipericina. Alíquotas foram espalhadas em placas de Petri contendo meio sólido, as unidades formadoras de colônias foram contadas após incubação e as frações de sobrevivência calculadas

  2. Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

    The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm-3 H2O2 was induced in both AB1157 and B/r by pretreating growing cells with 30 μmol dm-3 H2O2. Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 μmol dm-3 H2O2, in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H2O2, as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H2O2 scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions. (author)

  3. Ultraviolet (193, 216 and 254 nm) photoinactivation of Escherichia coli strains with different repair deficiencies

    Escherichia coli K12 bacteria strains AB1157 (repair-deficient wild-type, uvrA+ recA+), AB1886 (uvrA-), AB2463 (recA-) and AB2480 (uvrA- recA-) were exposed to 254 nm germicidal UV and 216 or 193 nm laser radiation. The mean lethal incident dose (D37) for AB1157 does not change significantly with wavelength, whereas it increases for the other strains on going from λirr = 254 to 193 nm, e.g., eightfold for AB2480. Quantum yields for inactivation, due to light absorbed by the chromosomal DNA, have been estimated from the D37 values. The large differences in D37 between uvrA+ and uvrA- strains indicate a significant contribution of pyrimidine dimers and (6-4) photoproducts to photodamage of DNA in the cells. The formation of dimers even with λirr = 193 nm is supported by the result that the photoreactivable sector is larger than 63%. Inactivation of E. coli upon irradiation at 193 and 216 nm is therefore due to damage to intracellular DNA rather than to membrane or protein damage as is the case for mammalian cells. The ratio of the lethal doses for AB1157 vs AB2480 is ∼900 with λirr = 254 nm, but only 160 with λirr = 193 nm. We propose that this is due to the better repair of photodimers and (6-4) photoproducts than of damage induced by photoionization via upper excited states. Irradiation at 193 nm inactivates AB1157 mainly by damage due to photoionization and AB2480 by damage due to photodimers in the chromosomal DNA. 51 refs., 3 figs., 5 tabs

  4. Ultraviolet (193, 216 and 254 nm) photoinactivation of Escherichia coli strains with different repair deficiencies

    Gurzadyan, G.G.; Goerner, H.; Schulte-Frohlinde, D. [Max-Planck-Institut fuer Strahlenchemie, Muelheim an der Ruhr (Germany)

    1995-03-01

    Escherichia coli K12 bacteria strains AB1157 (repair-deficient wild-type, uvrA{sup +} recA{sup +}), AB1886 (uvrA{sup {minus}}), AB2463 (recA{sup {minus}}) and AB2480 (uvrA{sup {minus}} recA{sup {minus}}) were exposed to 254 nm germicidal UV and 216 or 193 nm laser radiation. The mean lethal incident dose (D{sub 37}) for AB1157 does not change significantly with wavelength, whereas it increases for the other strains on going from {lambda}{sub irr} = 254 to 193 nm, e.g., eightfold for AB2480. Quantum yields for inactivation, due to light absorbed by the chromosomal DNA, have been estimated from the D{sub 37} values. The large differences in D{sub 37} between uvrA{sup +} and uvrA{sup {minus}} strains indicate a significant contribution of pyrimidine dimers and (6-4) photoproducts to photodamage of DNA in the cells. The formation of dimers even with {lambda}{sub irr} = 193 nm is supported by the result that the photoreactivable sector is larger than 63%. Inactivation of E. coli upon irradiation at 193 and 216 nm is therefore due to damage to intracellular DNA rather than to membrane or protein damage as is the case for mammalian cells. The ratio of the lethal doses for AB1157 vs AB2480 is {approx}900 with {lambda}{sub irr} = 254 nm, but only 160 with {lambda}{sub irr} = 193 nm. We propose that this is due to the better repair of photodimers and (6-4) photoproducts than of damage induced by photoionization via upper excited states. Irradiation at 193 nm inactivates AB1157 mainly by damage due to photoionization and AB2480 by damage due to photodimers in the chromosomal DNA. 51 refs., 3 figs., 5 tabs.

  5. Post-UV survival and mutagenesis in DNA repair-proficient and -deficient strains of Escherichia coli K-12 grown in 5-azacytidine to inhibit DNA cytosine methylation: evidence for mutagenic excision repair.

    Radnedge, L; Pinney, R J

    1993-03-01

    Inhibition of cytosine methylation by growth in 5-azacytidine (5-azaC), did not affect the sensitivities to DNA damage induced by exposure to ultraviolet light (UV) of Escherichia coli K-12 strains AB1157 dcm+, which is fully DNA repair-proficient, LR68 (a dcm derivative of AB1157), JC3890 dcm+ uvrB, deficient in error-free excision repair, TK702 dcm+ umuC, deficient in error-prone repair, or TK501 dcm+ uvrB umuC, which lacks both excision repair and error-prone repair. However, growth in 5-azaC increased the post-UV survival of strains AB2463 recA(Def), AB2470 recB and AB2494 lexA(Ind-), which are deficient in the induction or expression of recombination repair or error-prone repair of DNA. Spontaneous mutation frequencies were increased in strains LR68, AB2463, AB2470 and AB2494 by growth in 5-azaC, but remained unaltered in strains AB1157, JC3890, TK702 or TK501. Growth in 5-azaC significantly increased UV-induced mutation frequencies in strains AB2463 and AB2470, significantly reduced UV-induced mutation in strain JC3890, but had little effect on UV-induced mutation in the other strains. The results suggest that 5-azaC may induce a normally error-free DNA repair pathway to become error-prone and therefore genotoxic. PMID:7683337

  6. Post-UV survival and mutagenesis in DNA repair-proficient and -deficient strains of Escherichia coli K-12 grown in 5-azacytidine to inhibit DNA cytosine methylation: evidence for mutagenic excision repair

    Inhibition of cytosine methylation by growth in 5-azacytidine (5-azaC), did not affect the sensitivities to DNA damage induced by exposure to ultraviolet light (UV) of Escherichia coli K-12 strains AB1157 dcm+, which is fully DNA repair-proficient, LR68 (a dcm derivative of AB1157), JC3890 dcm+ uvr B, deficient in error-free excision repair, TK702 dcm+ umuC, deficient in error-prone repair, or TK501 dcm+ uvrB umuC, which lacks both excision repair and error-prone repair. However, growth in 5-azaC increased the post-UV survival of strains AB2463 recA(Def), AB2470 recB and AB2494 lexA(Ind-), which are deficient in the induction or expression of recombination repair or error-prone repair of DNA. Spontaneous mutation frequencies were increased in strains LR68, AB2463, AB2470 and AB2494 by growth in 5-azaC, but remained unaltered in strains AB1157, JC3890, TK702 or TK501. Growth in 5-azaC significantly increased UV-induced mutation frequencies in strains AB2463 and AB2470, significantly reduced UV-induced mutation in strain JC3890, but had little effect on UV-induced mutation in the other strains. The results suggest that 5-azaC may induce a normally error-free DNA repair pathway to become error-prone and therefore genotoxic. (Author)

  7. Bear

    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?

  8. Complete Genome Sequence of Mayaro Virus (Togaviridae, Alphavirus) Strain BeAr 20290 from Brazil

    Espósito, Danillo Lucas Alves; da Fonseca, Benedito Antônio Lopes

    2015-01-01

    We report here the complete genome sequence of Mayaro virus strain BeAr 20290 isolated from Haemagogus mosquitoes in 1960. The sequence presented here includes all nonstructural and structural proteins and the 5′- and 3′-untranslated (UTR) regions.

  9. Colistin Resistance mcr-1-Gene-Bearing Escherichia coli Strain from the United States

    Ladely, Scott R.; Plumblee, Jodie R.; Hall, M. Carolina; Simpson, Sheron A.; Ballard, Linda L.; Scheffler, Brian E.; Genzlinger, Linda L.; Cook, Kimberly L.

    2016-01-01

    Transmissible colistin resistance in the form of an mcr-1-gene-bearing plasmid has been recently reported in Enterobacteriaceae in several parts of the world. We report here the completed genome sequence of an Escherichia coli strain isolated from swine in the United States that carried the mcr-1 gene on an IncI2-type plasmid. PMID:27587816

  10. Post-UV survival and mutagenesis in DNA repair-proficient and -deficient strains of Escherichia coli K-12 grown in 5-azacytidine to inhibit DNA cytosine methylation: evidence for mutagenic excision repair

    Radnedge, L.; Pinney, R.J. (London Univ. (United Kingdom). Dept. of Pharmaceutics)

    1993-03-01

    Inhibition of cytosine methylation by growth in 5-azacytidine (5-azaC), did not affect the sensitivities to DNA damage induced by exposure to ultraviolet light (UV) of Escherichia coli K-12 strains AB1157 dcm[sup +], which is fully DNA repair-proficient, LR68 (a dcm derivative of AB1157), JC3890 dcm[sup +] uvr B, deficient in error-free excision repair, TK702 dcm[sup +] umuC, deficient in error-prone repair, or TK501 dcm[sup +] uvrB umuC, which lacks both excision repair and error-prone repair. However, growth in 5-azaC increased the post-UV survival of strains AB2463 recA(Def), AB2470 recB and AB2494 lexA(Ind[sup -]), which are deficient in the induction or expression of recombination repair or error-prone repair of DNA. Spontaneous mutation frequencies were increased in strains LR68, AB2463, AB2470 and AB2494 by growth in 5-azaC, but remained unaltered in strains AB1157, JC3890, TK702 or TK501. Growth in 5-azaC significantly increased UV-induced mutation frequencies in strains AB2463 and AB2470, significantly reduced UV-induced mutation in strain JC3890, but had little effect on UV-induced mutation in the other strains. The results suggest that 5-azaC may induce a normally error-free DNA repair pathway to become error-prone and therefore genotoxic. (Author).

  11. Dynamic torsional response of pre-strained end bearing pile embedded in pre-strained isotropic saturated soil medium

    胡文韬; 夏唐代; 张智卿

    2013-01-01

    The influence of initial strain state on the dynamic response of an end bearing pile embedded in isotropic saturated soil is investigated through the linearized theory of small elastic perturbation superposed on largely stressed bodies. The governing equations for soil, based on Biot’s poroelasticity theory, are derived in the cylindrical coordinates, and the pile is modeled by using the one-dimensional elastic theory. The analytical solutions of pile impedance, frequency response of both twist angle and time history of velocity response are obtained by using of separation of variables technique. Finally, a parametric study of the influence of initial strains on the torsional impedance, twist angle, and velocity response at the top of the pile is carried out.

  12. Utilization of a thermosensitive episome bearing transposon TN10 to isolate Hfr donor strains of Erwinia carotovora subsp. chrysanthemi.

    Kotoujansky, A; Lemattre, M; Boistard, P

    1982-04-01

    A thermosensitive episome bearing the transposon Tn10, F(Ts)::Tn10 Lac+, has been successfully transferred from Escherichia coli to several wild strains of the enterobacteria Erwinia carotovora subsp. chrysanthemi, which are pathogenic on Saintpaulia ionantha. In one of these strains, all of the characters controlled by this episome (Lac+, Tetr, Tra+) were expressed, and its replication was stopped at 40 degrees C and above. At 30 degrees C, the episome was easily transferred between strains derived from E. carotovora subsp. chrysanthemi 3937j and to E coli. Hfr donor strains were obtained from a F' strain of 3937j by selecting clones which grew at 40 degrees C on plates containing tetracycline. One of these strains, Hfrq, was examined in more detail: the characters Lac+ and Tetr were stabilized and did not segregate higher than its parental F' strain. The mating was most efficient at 37 degrees C on a membrane. Hfrq transferred its chromosome to recipient strains at high frequency and in a polarized fashion, as evidenced by the gradient of transfer frequencies, the kinetics of marker entry (in interrupted mating experiments), and the analysis of linkage between different markers. The chromosome of Hfrq was most probably transferred in the following sequence: origin...met...xyl...arg...ile...leu...thr...cys...pan...ura...gal...trp...his. ..pur... Moreover, this genetic transfer system proved to be efficient in strain construction. PMID:6277860

  13. Anterior cruciate ligament strain and tensile forces for weight-bearing and non-weight-bearing exercises: a guide to exercise selection.

    Escamilla, Rafael F; Macleod, Toran D; Wilk, Kevin E; Paulos, Lonnie; Andrews, James R

    2012-03-01

    There is a growing body of evidence documenting loads applied to the anterior cruciate ligament (ACL) for weight-bearing and non-weight-bearing exercises. ACL loading has been quantified by inverse dynamics techniques that measure anterior shear force at the tibiofemoral joint (net force primarily restrained by the ACL), ACL strain (defined as change in ACL length with respect to original length and expressed as a percentage) measured directly in vivo, and ACL tensile force estimated through mathematical modeling and computer optimization techniques. A review of the biomechanical literature indicates the following: ACL loading is generally greater with non-weight-bearing compared to weight-bearing exercises; with both types of exercises, the ACL is loaded to a greater extent between 10° to 50° of knee flexion (generally peaking between 10° and 30°) compared to 50° to 100° of knee flexion; and loads on the ACL change according to exercise technique (such as trunk position). Squatting with excessive forward movement of the knees beyond the toes and with the heels off the ground tends to increase ACL loading. Squatting and lunging with a forward trunk tilt tend to decrease ACL loading, likely due to increased hamstrings activity. During seated knee extension, ACL force decreases when the resistance pad is positioned more proximal on the anterior aspect of the lower leg, away from the ankle. The evidence reviewed as part of this manuscript provides objective data by which to rank exercises based on loading applied to the ACL. The biggest challenge in exercise selection post-ACL reconstruction is the limited knowledge of the optimal amount of stress that should be applied to the ACL graft as it goes through its initial incorporation and eventual maturation process. Clinicians may utilize this review as a guide to exercise selection and rehabilitation progression for patients post-ACL reconstruction. PMID:22387600

  14. The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density

    Rubin, Clinton T.; Seeherman, Howard; Qin, Yi-Xian; Gross, Ted S.

    2013-01-01

    Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain...

  15. Complete Genome Sequence of a Rabies Virus Strain Isolated from a Brown Bear (Ursus arctos) in Primorsky Krai, Russia (November 2014)

    Deviatkin, Andrei A.; Ananiev, Vasily Y.; Dedkov, Vladimir G.; Shipulin, German A.; Sokol, Nataliya N.; Dombrovskaya, Irina E.; Galkina, Irina V.; Shmelev, Mikhail E.; Gorelikov, Vladimir N.; Kozhan, Valentina N.; Prosyannikova, Marina N.; Aramilev, Sergei V.; Fomenko, Pavel V.

    2016-01-01

    We report here the complete genome sequence (GenBank KP997032) of rabies virus strain RABV/Ursus arctos/Russia/Primorye/PO-01/2014, isolated in November 2014 from a brown bear (Ursus arctos) that attacked a person in Primorsky Krai (Russian Federation). This strain was clustered into the Eurasian genetic subgroup of genotype 1 (street rage). PMID:27389270

  16. The use of slow strain rate technique for studying stress corrosion cracking of an advanced silver-bearing aluminum-lithium alloy

    In the present study, stress corrosion cracking (SCC) behavior of naturally aged advanced silver-bearing Al-Li alloy in NaCl solution was investigated using slow strain rate test (SSRT) method. The SSRT’s were conducted at different strain rates and applied potentials at room temperature. The results were discussed based on percent reductions in tensile elongation in a SCC-causing environment over those in air tended to express the SCC susceptbility of the alloy under study at T3. The SCC behavior of the alloy was also discussed based on the microstructural and fractographic examinations

  17. The use of slow strain rate technique for studying stress corrosion cracking of an advanced silver-bearing aluminum-lithium alloy

    Frefer, Abdulbaset Ali; Raddad, Bashir S. [Department of Mechanical and Industrial Engineering/Tripoli University, Tripoli (Libya); Abosdell, Alajale M. [Department of Mechanical Engineering/Mergeb University, Garaboli (Libya)

    2013-12-16

    In the present study, stress corrosion cracking (SCC) behavior of naturally aged advanced silver-bearing Al-Li alloy in NaCl solution was investigated using slow strain rate test (SSRT) method. The SSRT’s were conducted at different strain rates and applied potentials at room temperature. The results were discussed based on percent reductions in tensile elongation in a SCC-causing environment over those in air tended to express the SCC susceptbility of the alloy under study at T3. The SCC behavior of the alloy was also discussed based on the microstructural and fractographic examinations.

  18. Human rotavirus strains bearing VP4 gene P[6] allele recovered from asymptomatic or symptomatic infections share similar, if not identical, VP4 neutralization specificities

    A rotavirus VP4 gene P[6] allele has been documented in a number of countries to be characteristically associated with an endemic predominantly asymptomatic infection in neonates in maternity hospital nurseries. The mechanisms underlying the endemicity and asymptomatic nature of such neonatal infections remain unknown. Rotavirus strains sharing this same P genotype, however, have more recently been recovered from an increasing number of symptomatic diarrheal episodes in infants and young children in various parts of the world. Previously, we have shown that an asymptomatic P[6] rotavirus neonatal infection is not associated with a unique VP7 (G) serotype but may occur in conjunction with various G types. Although amino acid sequence comparisons of the VP4 gene between selected 'asymptomatic' and 'symptomatic' P[6] rotavirus strains have been reported and yielded information concerning their VP4 genotypes, serotypic comparisons of the outer capsid spike protein VP4 of such viruses have not been studied systematically by two-way cross-neutralizations. We determined the VP4 neutralization specificities of four asymptomatic and four symptomatic P[6] strains: two each of asymptomatic and symptomatic strains by two-way tests, and two each of additional asymptomatic and symptomatic strains by one-way tests. Both asymptomatic and symptomatic P[6] strains were shown to bear similar, if not identical, VP4 neutralization specificities. Thus, P[6] rotavirus strains causing asymptomatic or symptomatic infections did not appear to belong to unique P (VP4) serotypes. In addition, a close VP4 serotypic relationship between human P[6] rotavirus strains and the porcine P[6] rotavirus Gottfried strain was confirmed

  19. INFLUENCE OF THE SATURATION PERCENTAGE OF THE CLAY-BEARING SOIL ON ITS STRESS-STRAIN STATE

    Ter-Martirosyan Zaven Grigorevich; Nguyen Huy Hiep Huy Hiep

    2012-01-01

    The authors propose new analytical and numerical solutions to develop an advanced method of assessment of the stress-strain state of unsaturated clay soils exposed to external loading. The research findings demonstrate that the stress-strain state of the soil exposed to distributed loading in the half-space b = 2a is complex and homogeneous. It depends on the percentage of saturation and on the excessive pore pressure based on the saturation percentage. At the interim stage, when ...

  20. Interaction between recrystallization and strain-induced precipitation in a high Nb- and N-bearing austenitic stainless steel: Influence of the interpass time

    Silva, M.B.R., E-mail: marianabdrs@gmail.com [Department of Materials Engineering, UFSCar, Via Washington Luis, Km 235, 13565-905 São Carlos, SP (Brazil); Gallego, J. [Department of Mechanical Engineering, UNESP, Avenida Brasil, 56, 15385-000 Ilha Solteira, SP (Brazil); Cabrera, J.M. [Department of Materials Science and Metallurgical Engineering, Polytechnic University of Catalunya, Avenida Diagonal 647, 08028 Barcelona (Spain); Fundacio CTM Centre Tecnologic, Plaza de la Ciencia 2, 08243 Manresa (Spain); Balancin, O. [Department of Materials Engineering, UFSCar, Via Washington Luis, Km 235, 13565-905 São Carlos, SP (Brazil); Jorge, A.M., E-mail: moreira@dema.ufscar.br [Department of Materials Engineering, UFSCar, Via Washington Luis, Km 235, 13565-905 São Carlos, SP (Brazil)

    2015-06-18

    In this work, we studied the influence of the interpass time (20 and 5 s) on the interaction between recrystallization and strain-induced precipitation occurring during multiple passes' deformations under continuous cooling conditions in a high niobium- and nitrogen-bearing austenitic stainless steel (ISO 5832-9). The correlation between microstructure evolution and hot mechanical properties was performed by physical simulation using hot torsion tests. The microstructure evolution was analyzed by optical microscopy, transmission electron microscopy and electron back scattered diffraction (EBSD). This technique indicated that dynamic recrystallization occurred at the first passes promoting an excellent grain refinement. On the other hand, shorter interpass time (5 s) allowed higher volume fraction of smallest precipitates than larger interpass time (20 s). After soaking, only TiNbN precipitates were found, whereas, Z-phase (CrNbN) and NbN were formed during thermomechanical processing. Particles with sizes between 20 and 50 nm were effective to pin grain boundaries and dislocations.

  1. Interaction between recrystallization and strain-induced precipitation in a high Nb- and N-bearing austenitic stainless steel: Influence of the interpass time

    In this work, we studied the influence of the interpass time (20 and 5 s) on the interaction between recrystallization and strain-induced precipitation occurring during multiple passes' deformations under continuous cooling conditions in a high niobium- and nitrogen-bearing austenitic stainless steel (ISO 5832-9). The correlation between microstructure evolution and hot mechanical properties was performed by physical simulation using hot torsion tests. The microstructure evolution was analyzed by optical microscopy, transmission electron microscopy and electron back scattered diffraction (EBSD). This technique indicated that dynamic recrystallization occurred at the first passes promoting an excellent grain refinement. On the other hand, shorter interpass time (5 s) allowed higher volume fraction of smallest precipitates than larger interpass time (20 s). After soaking, only TiNbN precipitates were found, whereas, Z-phase (CrNbN) and NbN were formed during thermomechanical processing. Particles with sizes between 20 and 50 nm were effective to pin grain boundaries and dislocations

  2. Journal bearing

    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. Draft Genome Sequences of Seven Bacterial Strains Isolated from a Polymicrobial Culture of Coccolith-Bearing (C-Type) Emiliania huxleyi M217

    Rosana, Albert Remus R.; Orata, Fabini D.; Xu, Yue; Simkus, Danielle N.; Bramucci, Anna R.; Boucher, Yan

    2016-01-01

    Strains of Rhodobacteraceae, Sphingomonadales, Alteromonadales, and Bacteroidetes were isolated from a polymicrobial culture of the coccolith-forming (C-type) haptophyte Emiliania huxleyi strain M217. The genomes encode genes for the production of algal growth factors and the consumption of their hosts’ metabolic by-products, suggesting that the polymicrobial culture harbors many symbiotic interactions. PMID:27417845

  4. Hydrodynamic bearings

    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.

  5. Bioalteration of synthetic Fe(III)-, Fe(II)-bearing basaltic glasses and Fe-free glass in the presence of the heterotrophic bacteria strain Pseudomonas aeruginosa: Impact of siderophores

    Perez, Anne; Rossano, Stéphanie; Trcera, Nicolas; Huguenot, David; Fourdrin, Chloé; Verney-Carron, Aurélie; van Hullebusch, Eric D.; Guyot, François

    2016-09-01

    This study aims to evaluate the role of micro-organisms and their siderophores in the first steps of the alteration processes of basaltic glasses in aqueous media. In this regard, three different types of glasses - with or without iron, in the reduced Fe(II) or oxidized Fe(III) states - were prepared on the basis of a simplified basaltic glass composition. Control and Pseudomonas aeruginosa inoculated experiments were performed in a buffered (pH 6.5) nutrient depleted medium to stimulate the production of the pyoverdine siderophore. Results show that the presence of P. aeruginosa has an effect on the dissolution kinetics of all glasses as most of the calculated elemental release rates are increased compared to sterile conditions. Reciprocally, the composition of the glass in contact with P. aeruginosa has an impact on the bacterial growth and siderophore production. As an essential nutrient for this microbial strain, Fe notably appears to play a central role during biotic experiments. Its presence in the glass stimulates the bacterial growth and minimizes the synthesis of pyoverdine. Moreover the initial Fe2+/Fe3+ ratio in the glasses modulates this synthesis, as pyoverdine is not detected at all in the system in contact with Fe(III)-bearing glass. Finally, the dissolution rates appear to be correlated to siderophore concentrations as they increase with respect to sterile experiments in the order Fe(III)-bearing glass < Fe(II)-bearing glass < Fe-free glass. This increase is attributed to complexation reactions between siderophores and Fe or Al for Fe(II)-bearing glass or Fe-free glass, respectively. The dissolution of an Fe-free glass is significantly improved in the presence of bacteria, as initial dissolution rates are increased by a factor of 3. This study attests to the essential role of siderophores in the P. aeruginosa-promoted dissolution processes of basaltic glasses as well as to the complex relationships between the nutritional potential of the glass and

  6. Bearing structures

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

  7. Failure tests of laminated rubber bearings

    Three different types of rubber bearing - natural rubber bearing (NRB), lead-rubber bearing (LRB), and high-damping rubber bearing (HRB) - were tested up to failure under various combinations of axial and shear forces. The test results are summarized as follows: 1) Offset shear strain greatly affects tensile behavior and failure. 2) Axial stress or strain does not so greatly affect shear behavior and failure. 3) The characteristics of NBR and LRB are almost independent of strain rate, but those of HRB depend greatly on it. 4) Cyclic loading affects large-deformation behavior and failure to some extent. 5) failure limits which include the interaction between axial stress and shear strain were quantitatively evaluated. 6) A lead plug of LRB has no bad influence on failure. These will be very useful for developing an ultimate response prediction technique, which is necessary to establish rational design philosophy of base isolation systems for FBR plants. (author)

  8. Tooling Converts Stock Bearings To Custom Bearings

    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.

  9. Bioalteration of synthetic Fe(III)-, Fe(II)-bearing basaltic glasses and Fe-free glass in the presence of the heterotrophic bacteria strain Pseudomonas aeruginosa: Impact of siderophores

    Perez, Anne; Rossano, Stéphanie; Trcera, Nicolas; Huguenot, David; Fourdrin, Chloé; Verney-Carron, Aurélie; van Hullebusch, Eric D.; Guyot, François

    2016-09-01

    This study aims to evaluate the role of micro-organisms and their siderophores in the first steps of the alteration processes of basaltic glasses in aqueous media. In this regard, three different types of glasses - with or without iron, in the reduced Fe(II) or oxidized Fe(III) states - were prepared on the basis of a simplified basaltic glass composition. Control and Pseudomonas aeruginosa inoculated experiments were performed in a buffered (pH 6.5) nutrient depleted medium to stimulate the production of the pyoverdine siderophore. Results show that the presence of P. aeruginosa has an effect on the dissolution kinetics of all glasses as most of the calculated elemental release rates are increased compared to sterile conditions. Reciprocally, the composition of the glass in contact with P. aeruginosa has an impact on the bacterial growth and siderophore production. As an essential nutrient for this microbial strain, Fe notably appears to play a central role during biotic experiments. Its presence in the glass stimulates the bacterial growth and minimizes the synthesis of pyoverdine. Moreover the initial Fe2+/Fe3+ ratio in the glasses modulates this synthesis, as pyoverdine is not detected at all in the system in contact with Fe(III)-bearing glass. Finally, the dissolution rates appear to be correlated to siderophore concentrations as they increase with respect to sterile experiments in the order Fe(III)-bearing glass bacteria, as initial dissolution rates are increased by a factor of 3. This study attests to the essential role of siderophores in the P. aeruginosa-promoted dissolution processes of basaltic glasses as well as to the complex relationships between the nutritional potential of the glass and its dissolution rates.

  10. Seismic isolation rubber bearings for nuclear facilities

    This paper describes results of biaxial breaking tests by compression and shear and by tension and shear for seismic isolation rubber bearings with bolted-type connections. The bearings used in the tests were low-damping rubber bearings, high-damping rubber bearings, and lead-rubber bearings. Three modes of failure of the bolted-type bearings were observed in the tests. They are the breaking failure by tension and shear; the breaking failure by compression and shear; and the buckling failure by compression and shear. The first and the second modes of failures are almost independent of the types and the sizes of the bearings. The breaking conditions of those failure modes are described in the axial stress-shear strain plane. This expression is useful for the evaluation of safety margins of the bearings. The paper outlines the basic design of the nuclear-grade bearings which were used for large-scale rubber bearing tests in a research project for seismic isolation of fast breeder reactor (FBR) plants. The paper also discusses the protection method against aging and the quality control which are important for implementation

  11. uv-induced alleviation of K-specific restriction of bacteriophage lambda

    A partial release of K-specific restriction of phage lambda grown in Escherichia coli C was observed when E. coli K strains AB1157 (having wild-type repair of uv-produced DNA damage) and AB1886 (uvrA) were irradiated with uv light before infection. The effect occurred in AB1886 at lower uv fluences than it did in AB1157. Little or no release of restriction was observed when AB2463 (recA) or AB2494 (lex-1) was used. Such release of restriction appears to be another of the uv-induced phenomena associated with ''SOS'' repair

  12. Restoration of bearings

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

    1977-01-01

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

  13. Passive magnetic bearing configurations

    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.

  14. Maintenance Free Bearings

    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...

  15. Teddy Bear Stories

    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...

  16. Bearing pad to pressure tube contact simulation

    Thermal creep strain deformation is a very important pressure tube failure mechanism. During a postulated LOCA (loss of coolant accident) with failure of emergency core injection sys- tem (ECIS), the fuel cladding temperature rapidly increases and the pressure tube becomes completely dry in a few seconds after flow stagnation occurs. Subsequently, the pressure tube circumference is heated by thermal radiation except at the spots where the bearing pads are in direct contact with the pressure tube. Therefore, the localized hot spots are developed on the pressure tube's inner surface under the bearing pads. The main objective of this paper is to evaluate the local thermal-mechanical deformation of a pressure tube in a CANDU reactor and to investigate the fuel channel integrity under localized contact between bearing pad and pressure tube. Furthermore, the mechanistic models are validated against the experimental works per- formed at WRL (Whiteshell research laboratory). Calculations are performed using the finite element method in which the heat, thermal mechanical and creep strain equations are solved, simultaneously. According to the experimental set up, the heat conduction from bearing pads to the inner surface of the pressure tube with appropriate convective and radiation boundary conditions has been simulated. Furthermore, the thermal creep strain deformation has been obtained for when the pressure tube is still under operational condition. It is observed that the pressure tube thermal strain will occur if sufficient high temperature is reached however, depending on the severity of flow degradation in the fuel channel, these localized hot spots could represent a potential creep strain failure of the pressure tube. Whether the pressure tube would fail at these hot spots before contacting the calandria tube depends on the localized temperature and experienced pressure transients. Sensitivity analysis is performed in order to evaluate the contact conductance, the

  17. Bear Spray Safety Program

    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.

  18. Optimal Synchronizability of Bearings

    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...

  19. Bearing restoration by grinding

    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.

  20. EcoBears

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

    2015-01-01

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

  1. A study on creep properties of laminated rubber bearings. Pt. 1. Creep properties and numerical simulations of thick rubber bearings

    In this report, to evaluate creep properties and effects of creep deformation on mechanical properties of thick rubber bearings for three-dimensional isolation system, we show results of compression creep test for rubber bearings of various rubber materials and shapes and development of numerical simulation method. Creep properties of thick rubber bearings were obtained from compression creep tests. The creep strain shows steady creep that have logarithmic relationships between strain and time and accelerated creep that have linear relationships. We make numerical model of a rubber material with nonlinear viscoelastic constitutional equations. Mechanical properties after creep loading test are simulated with enough accuracy. (author)

  2. Development of GR/MR Chimeric Receptors and Their Response to Steroid Hormones

    2000-01-01

    We have established an effective and reliable technique of developing GR/MR chimeric receptors by DNA homologous recombination. To develop the method we transformed several different E. coli strains with a linearized plasmid containing full length of mGR(mouse GR) and hormone binding domain(HBD) of rMR(rat MR), the linear DNA undergoes recombination due to the homology of the mGR and the rMR and recircularize , and propagation in E. coli. PCR was performed to screen correct construction in which fusion between GR and MR took place. The constructs were digested with appropriate restriction endonucleases to test probable fusion sites of GR and HBD of MR. Precise fusion sites of GR and MR for constructs AB1157 # 2 , AB1157 # 18, AB 1157 # 22, AB1157 # 32, CMK603 # 6 were verified by DNA sequencing. Trans fection of COS- 7 cells with the constructs and subsequent treatment of transfected COS-7 cells with steroid hormones were carried out, the results showed that the constructs gave response to tested hormones. The study suggested that the GR/MR chimeric receptors can give rise to fusion proteins and their interactive function between hormone and receptor.

  3. Bearing fatigue investigation 3

    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.

  4. Arcturus and the Bears

    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.

  5. Ultra-precision bearings

    Wardle, F

    2015-01-01

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

  6. Management recommendations: Bear River

    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...

  7. Relationship among the repair and genetic recombination mechanisms. II. Effect of gamma radiation on the lambda recombination in E. coli AB1157 and AB1886; Relacion entre los mecanismos de reparacion y la recombinacion genetica. II. efecto de la radiacion gamma sobre la recombinacion de lambda en E. Coli AB1157 y AB1886

    Alcantara D, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1988-08-15

    The objective of the present work is to determine if the radiation gamma that is a good inductor of the answer SOS of Escherichia Coli but that it produces alterations in the DNA very different to those taken place by the light UV, it is able to stimulate the viral recombination. (Author)

  8. Gear bearing drive

    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.

  9. Rolling bearing analysis

    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.

  10. My Little Teddy Bear

    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.

  11. Shape memory alloy wire-based smart natural rubber bearing

    In this study, two types of smart elastomeric bearings are presented using shape memory alloy (SMA) wires. Due to the unique characteristics of SMAs, such as the superelastic effect and the recentering capability, the residual deformation in SMA-based natural rubber bearings (SMA-NRBs) is significantly reduced whereas the energy dissipation capacity is increased. Two different configurations of SMA wires incorporated in elastomeric bearings are considered. The effect of several parameters, including the shear strain amplitude, the type of SMA, the aspect ratio of the base isolator, the thickness of SMA wire, and the amount of pre-strain in the wires on the performance of SMA-NRBs is investigated. Rubber bearings are composed of natural rubber layers bonded to steel shims as reinforcement. Results show that ferrous SMA wire, FeNiCuAlTaB, with 13.5% superelastic strain and a very low austenite finish temperature (−62 °C), is the best candidate to be used in SMA-NRBs subjected to high shear strain amplitudes. In terms of the lateral flexibility and wire strain level, the smart rubber bearing with a cross configuration of SMA wires is more efficient. Moreover, the cross configuration can be implemented in high-aspect-ratio elastomeric bearings since the strain induced in the wire does not exceed the superelastic range. When cross SMA wires with 2% pre-strain are used in a smart NRB, the dissipated energy is increased by 74% and the residual deformation is decreased by 15%. (paper)

  12. Climate Drives Polar Bear Origins

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

  13. THE IN VITRO EVALUATION OF ortho-/meta-/para-ALKOXYPHENYLCARBAMIC ACID ESTERS BEARING 4-(2-FLUORO-/2-METHYLPHENYLPIPERAZIN-1-YL MOIETY AGAINST MYCOBACTERIUM TUBERCULOSIS H37Ra STRAIN

    Ivan Malík

    2014-02-01

    Full Text Available In a continual research of ortho-/meta-/para-alkoxyphenylcarbamic acid esters as antimycobacterially active compounds, the purpose of current paper was to in vitro screen the potency of the molecules containing incorporated substituted N-phenylpiperazin-1-yl moiety against attenuated M. tuberculosis H37Ra strain which was grown in Middlebrook broth, supplemented with Oleic-Albumin-Dextrose- Catalase supplement and mycobactin J (2 µg/mL as well. The susceptibility of concerned mycobacterial strain was investigated in a 96-well plate format, the plates were incubated at 37°C for 7 days. According to minimum inhibitory concentrations, as the lowest concentrations which prevented a visual colour change, it was observed that positional ortho-/meta-/para-alkoxy side chain isomerism as well as high lipophilicity did not decisively influenced the effectiveness of inspected compounds. Moreover, qualitatively different substitution within basic compartment in terms of electronic properties and possible hydrophobic interactions did not lead to the improvement in the activity.

  14. A technique to measure rotordynamic coefficients in hydrostatic bearings

    Capaldi, Russell J.

    1993-11-01

    An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal bearings. The bearing tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal bearing.

  15. Partial tooth gear bearings

    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.

  16. Blood Pump Bearing System

    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.

  17. Modular gear bearings

    Vranish, John M. (Inventor)

    2009-01-01

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

  18. Development of Flexible Bearing

    K.S.Mohanraj

    2014-06-01

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

  19. Flexure Bearing Reduces Startup Friction

    Clingman, W. Dean

    1991-01-01

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

  20. Active Magnetic Bearings – Magnetic Forces

    Kjølhede, Klaus

    2006-01-01

    the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision......Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  1. Active Magnetic Bearings – Magnetic Forces

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  2. Reliability for fluid bearings design

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

    2013-01-01

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

  3. Reliability of a hydrostatic bearing

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

    2013-01-01

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

  4. Households' Interest-bearing Assets

    Ellis Connolly; Fiona Fleming; Jarkko Jääskelä

    2012-01-01

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

  5. Centrifugally decoupling touchdown bearings

    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.

  6. Government Risk-Bearing

    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...

  7. Rotating plug bearing and seal

    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. Rotating plug bearing and seal

    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

  9. ANSWER: A bear paw.

    Ian BICKLE

    2012-01-01

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

  10. Gearbox Reliability Collaborative Investigation of High-Speed-Shaft Bearing Loads

    Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-06-01

    The loads and contact stresses in the bearings of the high speed shaft section of the Gearbox Reliability Collaborative gearbox are examined in this paper. The loads were measured though strain gauges installed on the bearing outer races during dynamometer testing of the gearbox. Loads and stresses were also predicted with a simple analytical model and higher-fidelity commercial models. The experimental data compared favorably to each model, and bearing stresses were below thresholds for contact fatigue and axial cracking.

  11. Gearbox Reliability Collaborative High Speed Shaft Tapered Roller Bearing Calibration

    Keller, J.; Guo, Y.; McNiff, B.

    2013-10-01

    The National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) is a project investigating gearbox reliability primarily through testing and modeling. Previous dynamometer testing focused upon acquiring measurements in the planetary section of the test gearbox. Prior to these tests, the strain gages installed on the planetary bearings were calibrated in a load frame.

  12. Anti-backlash gear bearings

    Vranish, John M. (Inventor)

    2009-01-01

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

  13. Geomechanical Modeling of Gas Hydrate Bearing Sediments

    Sanchez, M. J.; Gai, X., Sr.

    2015-12-01

    This contribution focuses on an advance geomechanical model for methane hydrate-bearing soils based on concepts of elasto-plasticity for strain hardening/softening soils and incorporates bonding and damage effects. The core of the proposed model includes: a hierarchical single surface critical state framework, sub-loading concepts for modeling the plastic strains generally observed inside the yield surface and a hydrate enhancement factor to account for the cementing effects provided by the presence of hydrates in sediments. The proposed framework has been validated against recently published experiments involving both, synthetic and natural hydrate soils, as well as different sediments types (i.e., different hydrate saturations, and different hydrates morphologies) and confinement conditions. The performance of the model in these different case studies was very satisfactory.

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

    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

  15. Bearings only naval tracking

    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.

  16. Self lubricating fluid bearings

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

  17. Loss of characteristic radiation resistance by mutation of Micrococcus radiodurans

    The exceptional radioresistance of M. radiodurans was lost by a mutation, and the isolated mutant, KH840, had almost the same radiosensitivity as E. coli K12 AB1157 or B/r. DNA-strand scissions in this mutant were rejoined partly during post-irradiation incubation. Reduced DNA polymerizing activity and extensive degradation of the product was observed in vitro in the crude extract from the sensitive strain. The lower repair capability is not accompanied by the reduced transformation frequency

  18. Superconducting bearings in flywheels

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

    1998-05-01

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

  19. Superconducting bearings in flywheels

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

  20. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model vali...... with respect to the instantaneous measured force obtained from the strain gauges signals)...... magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...

  1. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model vali...... with respect to the instantaneous measured force obtained from the strain gauges signals)...... magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...

  2. Computational design of rolling bearings

    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.

  3. Grease lubrication in rolling bearings

    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

  4. Hydrostatic and hybrid bearing design

    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

  5. Fish of Bear Lake, Utah

    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. Dynamic Analysis of Engine Bearings

    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.

  7. Autosizing Control Panel for Needle Bearing

    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...

  8. Superconducting bearings for flywheel applications

    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.

  9. Superconducting bearings for flywheel applications

    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...

  10. What about the Javan Bear?

    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

  11. Space Station alpha joint bearing

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  12. Fire safety of rubber bearings

    The objective of the study is to experimentally evaluate the fire resistance of the natural-rubber bearings to be incorporated into a Fast Reactor (FBR) under study. Four experiments were performed to look at the effect of bearing diameters and heating conditions on the performance. The full-scale specimen sustained the design-basis load for more than 3.5 hours under 'standard fire.' Medium-size bearings showed resistance for 2-4 hours, according to heating temperatures. The paper also summarizes the methods and the results of simulation analyses of rubber bearings subjected to load/temperature conditions under fire. The vertical deformation of the bearings can be calculated very well, using the temperature profiles obtained from testing. However, the heat transfer analyses did not give good results, especially in the cases/portions where heat was generated due to rubber combustion. (author)

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

    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...

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

    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.

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

    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)…

  16. eBear: An Expressive Bear-Like Robot

    Zhang, Xiao; Mollahosseini, Ali; B., Amir H. Kargar; Boucher, Evan; Voyles, Richard M.; Nielsen, Rodney; Mahoor, Mohammd H.

    2015-01-01

    This paper presents an anthropomorphic robotic bear for the exploration of human-robot interaction including verbal and non-verbal communications. This robot is implemented with a hybrid face composed of a mechanical faceplate with 10 DOFs and an LCD-display-equipped mouth. The facial emotions of the bear are designed based on the description of the Facial Action Coding System as well as some animal-like gestures described by Darwin. The mouth movements are realized by synthesizing emotions w...

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

    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.

  18. Mixed-mu superconducting bearings

    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.

  19. Nonlinear Control of Magnetic Bearings

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  20. Failure analysis of superconducting bearings

    Rastogi, Amit; Campbell, A M; Coombs, T A [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2006-06-01

    The dynamics of superconductor bearings in a cryogenic failure scenario have been analyzed. As the superconductor warms up, the rotor goes through multiple resonance frequencies, begins to slow down and finally touches down when the superconductor goes through its transition temperature. The bearing can be modelled as a system of springs with axial, radial and cross stiffness. These springs go through various resonant modes as the temperature of the superconductor begins to rise. We have presented possible explanations for such behavio0008.

  1. Failure analysis of superconducting bearings

    The dynamics of superconductor bearings in a cryogenic failure scenario have been analyzed. As the superconductor warms up, the rotor goes through multiple resonance frequencies, begins to slow down and finally touches down when the superconductor goes through its transition temperature. The bearing can be modelled as a system of springs with axial, radial and cross stiffness. These springs go through various resonant modes as the temperature of the superconductor begins to rise. We have presented possible explanations for such behaviour

  2. Genome Sequence of Chinese Porcine Parvovirus Strain PPV2010

    Cui, Jin; wang, xin; Ren, Yudong; Cui, Shangjin; Li, Guangxing; Ren, Xiaofeng

    2012-01-01

    Porcine parvovirus (PPV) isolate PPV2010 has recently emerged in China. Herein, we analyze the complete genome sequence of PPV2010. Our results indicate that the genome of PPV2010 bears mixed characteristics of virulent PPV and vaccine strains. Importantly, PPV2010 has the potential to be a naturally attenuated candidate vaccine strain.

  3. Designing Rolling-Element Bearings

    Moore, James D., Jr.

    2007-01-01

    Bearing Analysis Tool (BAT) is a computer program for designing rolling-element bearings for cryogenic turbomachines. BAT provides a graphical user interface (GUI) that guides the entry of data to develop mathematical models of bearings. The GUI breaks model data into logical subsets that are entered through logic-driven input screens. The software generates a threedimensional graphical model of a bearing as the data are entered. Most dataentry errors become immediately obvious in the graphical model. BAT provides for storage of all the data on a shaft/bearing system, enabling the creation of a library of proven designs. Data from the library can be transferred to subsequent projects by use of simple cut-and-paste routines. BAT includes a library of temperature- dependent cryogenic bearing-material properties for use in the mathematical models. BAT implements algorithms that (1) enable the user to select combinations of design and/or operating-condition parameters, and then (2) automatically optimize the design by performing trade studies over all of the parameter combinations. This feature enables optimization over a large trade space in a fraction of the time taken when using prior bearingmodel software.

  4. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  5. Bear reintroduction: Lessons and challenges

    Clark, Joseph D.; Huber, Djuro; Servheen, Christopher

    2002-01-01

    Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. Historically, one of the most successful programs was the reintroduction of 254 American black bears (Ursus americanus) from Minnesota to the Interior Highlands of Arkansas in the 1960s; that population has grown to >2,500 today. More recent efforts have involved fewer but better monitored animals and have sometimes employed techniques to improve site fidelity and survival. In Pennsylvania, for example, pregnant female American black bears were successfully translocated from winter dens, the premise being that the adult females would be less likely to return because of the presence of young cubs. That winter-release technique was compared to summer trapping and release in Tennessee; winter releases resulted in greater survival and reduced post-release movements. Homing has not been a problem for small numbers of brown bears (Ursus arctos) reintroduced to the Cabinet-Yaak ecosystem in Montana and Idaho and to the mountains of Austria and France. Reintroduction success appears to be correlated with translocation distance and is greater for subadults and females. As with any small population, reintroduced bear populations are susceptible to environmental variation and stochastic demographic and genetic processes. Although managers have focused on these biological barriers, sociopolitical impediments to bear reintroduction are more difficult to overcome. Poor public acceptance and understanding of bears are the main reasons some reintroduction programs have been derailed. Consequently, the public should be involved in the reintroduction process from the outset; overcoming negative public perceptions about bear reintroduction will be our greatest challenge.

  6. 49 CFR 229.69 - Side bearings.

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  7. 36 CFR 13.1236 - Bear orientation.

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  8. Dynamic Performance Characteristic Tests of Real Scale Lead Rubber Bearing for the Evaluation of Performance Criteria

    Dynamic characteristic tests of full scale lead rubber bearing were performed for the evaluation of performance criteria of isolation system for nuclear power plants. For the dynamic test for a full scale rubber bearing, two 1500mm diameter lead rubber bearings were manufactured. The viewpoints of this dynamic test are determination of an ultimate shear strain level of lead rubber bearing, behavior of rubber bearing according to static and dynamic input motion, sinusoidal and random (earthquake) motion, and 1-dimentional and 2-dimensional input motion. In this study, seismic isolation device tests were performed for the evaluation of performance criteria of isolation system. Through this test, it can be recognized that in the case of considering a mechanical property test, dynamic and multi degree of loading conditions should be determined. But these differences should be examined how much affect to the global structural behavior

  9. Superconductor bearings, flywheels and transportation

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  10. Superconductor bearings, flywheels and transportation

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS–FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  11. Future Bearing Surfaces in Total Hip Arthroplasty

    Chang, Jun-Dong

    2014-01-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom...

  12. Dynamic characteristics of lead rubber bearings with dynamic two-dimensional test equipment

    Although studies have previously been done on the static mechanical properties of lead rubber bearings, this study aims to grasp the dynamic characteristics of lead rubber bearings from experimental results, using two-dimensional dynamic test equipment which is designed to grasp in detail such dynamic characteristics as deformation capacity and proof stress. This paper describes the results from three types of tests: (1) dynamic mechanical properties tests, (2) cyclic loading tests, and (3) dynamic ultimate tests. Through these tests, it was confirmed that the dynamic characteristics of lead rubber bearings are independent of strain rate

  13. 'Dodo' and 'Baby Bear' Trenches

    2008-01-01

    NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  14. Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    2007-01-01

    Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model valid...... normalized with respect to the instantaneous measured force obtained from the strain gauges signals)....... the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor (ii) by measuring the input current and...

  15. Trends in Controllable Oil Film Bearings

    Santos, Ilmar

    2011-01-01

    This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing .......e., as tilting-pad bearings, multirecess journal bearings and plain bearings.......This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing...... the rotational speed ranges by improving damping and eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing startup torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable bearings can act as...

  16. Novel Super-Elastic Materials for Advanced Bearing Applications

    Dellacorte, Christopher

    2014-01-01

    Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Ni-Ti alloys are an emerging solution. Ni-Ti alloys are intermetallic materials that possess characteristics of both metals and ceramics. Ni-Ti alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. Ni-Ti alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of hard, resilient Ni-Ti alloys for corrosion-proof, shockproof bearing and gear applications are presented. Through a series of bearing and gear development projects, it is demonstrated that Ni-Tis unique blend of materials properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. Ni-Ti thus represents a new materials solution to demanding tribological applications.

  17. Mechanical properties and design method of thick rubber bearings for three dimensional base isolation

    Thick rubber bearings as 3-dimensional base isolators have been developed to reduce both horizontal and vertical seismic loads especially for equipment in Fast Breeder Reactors. In this report, a design method of thick rubber bearings is presented. Rubber bearing tests are conducted with 1/3 scale models to evaluate mechanical properties of thick rubber bearings including ultimate limits. In the tests, horizontal and vertical characteristics of 1/3 scale model are compared with those of 1/6 scale model to discuss scale effect of test specimen. Ultimate limits such as failure shear strain of thick rubber bearings are obtained under various lading conditions. From the test results, we confirm that full scale thick rubber bearing to satisfy requirements is feasible. Furthermore, to consider nonlinearity of vertical stiffness affected by vertical stress in the design of thick rubber bearings, Lindley's evaluation method of vertical stiffness is modified as an explicit form of vertical stress. We confirm that the presented method is efficient for design of the thick rubber bearings from comparing between test results and predicted values. (author)

  18. Development of design method of thick rubber bearings for three-dimensional base isolation

    Thick rubber bearings as 3-dimensional base isolators have been developed to reduce both horizontal and vertical seismic loads especially for equipment in Fast Breeder Reactors. In this report, a design method of thick rubber bearings is presented. To consider nonlinearity of vertical stiffness affected by vertical stress in the design of thick rubber bearings, Lindley's evaluation method of vertical stiffness is modified as an explicit form of vertical stress. We confirm that the presented method is efficient for design of the thick rubber bearings from comparing between test results and predicted values. Furthermore, rubber bearing tests are conducted with 1/3 scale models to evaluate mechanical properties of thick rubber bearings including ultimate limits. In the tests, horizontal and vertical characteristics of 1/3 scale model are compared with those of 1/6 scale model to discuss scale effect of test specimen. Ultimate limits such as failure shear strain of thick rubber bearings are obtained under various loading conditions. From the test results, we confirm that full scale thick rubber bearing to satisfy requirements is feasible. (author)

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

    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.

  20. Isotype profiles of anti-influenza antibodies in mice bearing the xid defect

    The humoral response to influenza A/PR8 virus was examined in the CAB/N and C3J.xid strains of mice, both of which bear an X-linked genetic defect (xid), and in strains lacking this defect. Hemagglutination-inhibiting antibody titers and measurement of virus-specific antibodies by solid-phase radioimmunoassay indicated that the xid defect does not impair the production of an adequate anti-influenza antibody response. However, investigation of the isotopes of PR8 virus-specific antibodies disclosed a relative decrease in the levels of IgG3 and IgG1 in the xid-bearing strains. This was observed after both intraperitoneal immunization and aerosol infection. The isotope differences were not reflected in the susceptibility of these strains to influenza virus infection

  1. Journal and Wave Bearing Impedance Calculation Software

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  2. Antimicrobial resistance markers of class 1 and class 2 integron-bearing Escherichia coli from irrigation water and sediments.

    Roe, Matthew T; Vega, Everardo; Pillai, Suresh D

    2003-07-01

    Municipal and agricultural pollution affects the Rio Grande, a river that separates the United States from Mexico. Three hundred and twenty-two Escherichia coli isolates were examined for multiple antibiotic resistance phenotypes and the prevalence of class 1 and class 2 integron sequences. Thirty-two (10%) of the isolates were resistant to multiple antibiotics. Four (13%) of these isolates contained class 1-specific integron sequences; one isolate contained class 2 integron-specific sequences. Sequencing showed that the class 1 integron-bearing strain contained two distinct gene cassettes, sat-1 and aadA. Although three of the four class 1 integron-bearing strains harbored the aadA sequence, none of the strains was phenotypically resistant to streptomycin. These results suggest that integron-bearing E. coli strains can be present in contaminated irrigation canals and that these isolates may not express these resistance markers. PMID:12890322

  3. Mobile bearing and fixed bearing total knee arthroplasty

    Dolfin, Marco; Saccia, Francesco

    2016-01-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  4. Effects of bearing deadbands on bearing loads and rotor stability

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  5. Live-trapping and handling brown bear

    US Fish and Wildlife Service, Department of the Interior — This paper reports techniques developed to live trap and handle brown bears on the Kodiak National Wildlife Refuge. The brown bears (Ursus middendorffi) on the...

  6. Brown bear telemetry and trapping: Special report

    US Fish and Wildlife Service, Department of the Interior — Brown bear studies were continued during the 1967 field season with emphasis on development of techniques for instrumenting bears with radio transmitters and...

  7. Goose Eggs Could Save Polar Bears

    孙淑敏

    2009-01-01

    Polar bears could avoid extinction despitemany starving to death in coming years, ac-cording to scientists and other observers whohave discovered that some of the bears havefound a new food source--goose and duckeggs.

  8. Shaft Center Orbit in Dynamically Loaded Bearings

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... the years. In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work, but the...

  9. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  10. Oil film pressure in hydrodynamic journal bearings

    Valkonen, Antti

    2009-01-01

    Hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in various machines. Therefore, knowing the true operating conditions of hydrodynamic journal bearings is essential to machine design. Oil film pressure is one of the key operating parameters describing the operating conditions in hydrodynamic journal bearings. Measuring the oil film pressure in bearings has been a demanding task and theref...

  11. Mercury in polar bears from Alaska

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  12. Technology development for indigenous water lubricated bearings

    Water Lubricated Bearings (WLB) are used in various mechanisms of fuel handling systems of PHWRs and AHWR. Availability and random failures of these bearings was a major factor in refuelling operations. Indigenous development of these bearings was taken up and 7 types of antifriction bearings in various sizes (totaling 37 variants) for PHWR, AHWR and Dhruva applications were successfully developed. This paper deals with various aspects of WLB development. (author)

  13. Numerical analysis of hydrogen-assisted rolling-contact fatigue of wind turbine bearings

    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.

  14. Thin film superconductor magnetic bearings

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  15. 49 CFR 229.64 - Plain bearings.

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  16. Passive Thermal Management of Foil Bearings

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  17. Hazards within the Bear Lake basin, Utah

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    The Bear Lake basin developed from fault subsidence that continues today, slowly deepening the lake along the eastern side. The Bear Lake graben is about 5 miles long and 4.3-8.6 miles wide. It extends across the Utah-Idaho border and involves faults on both eastern and western sides of Bear Lake....

  18. Virginia Tech Bear Researchers Ensure Populations

    Davis, Lynn

    2003-01-01

    The Cooperative Alleghany Bear Study (CABS) was initiated in 1994 as a 10-year study to ensure survival of Virginia's hunted black bear population of western Virginia. During the first six years of the study, researchers have placed radio collars on 376 of the 746 bears captured.

  19. The vented pressure fed gas journal bearing

    Hydrodynamic-type gas journal bearings with stabilising venting slots are often operated hydrostatically during starting-up as a means of 'jacking'. A simplified mathematical treatment of the circumferential gas flows in a vented, pressure-fed journal bearing is used to predict the relationship between load capacity, bearing geometry and gas properties. (author)

  20. Cool Polar Bears: Dabbing on the Texture

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  1. Fractal analysis of polar bear hairs

    Wang Qing-Li

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus are of superior properties such as the excellent thermal protection. Why do polar bears can resist such cold environment? The paper concludes that its fractal porosity plays an important role, and its fractal dimensions are very close to the golden mean, 1.618, revealing the possible optimal structure of polar bear hair.

  2. Microstructural degradation of bearing steels

    Solano Alvarez, Wilberth

    2015-01-01

    The aim of the work presented in this thesis is to clarify one of the most fundamental aspects of fatigue damage in bearings steels through critical experiments, in particular whether damage in the form of cracks precedes hard ?white-etching matter" formation, which is carbon supersaturated nanoscaled ferrite. Heat treatments have been designed to create four different crack types and distributions: scarce martensite plate cracks, fine grain boundary cracks, abundant martensite plate cracks, ...

  3. Elid superfinishing of spherical bearings

    Raffles, Mark H.

    2007-01-01

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

  4. Risk-bearing and Entrepreneurship

    Newman, Andrew

    2007-01-01

    In the 'Knightian' theory of entrepreneurship, entrepreneurs provide insurance to workers by paying fixed wages and bear all the risk of production. This paper endogenizes entrepreneurial risk by allowing for optimal insurance contracts as well as the occupational self-selection. Moral hazard prevents full insurance; increases in an agent’s wealth then entail increases in risk borne. Thus, even under decreasing risk aversion, there are robust instances in which workers are wealthier than entr...

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

    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.

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

    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.

  7. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  8. Ball Bearing Stacking Automation System

    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

  9. Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation

    Enemark, Søren; Santos, Ilmar; Savi, Marcelo A.

    2015-01-01

    hysteretic stress-strain relations which may be utilized for damping purposes. These ideas are tested in this study on a dedicated test-rig, consisting of a rigid shaft and disc held vertically by passive magnetic bearings, where the damping is low. The bearing housings is flexibly supported by shape memory...... alloy helical springs, and because of high dynamic coupling between shaft and bearing housing, the shape memory alloy springs are able to reduce vibration in the shaft. The shape memory alloy springs are characterized by force-displacement tests in different temperatures. Transients of step...... perturbations and mass imbalance responses of the rotor-bearing system at different temperatures and excitation frequencies are carried out to determine the dynamic behaviour of the system. The behaviour and the performance in terms of vibration reduction and system adaptability are compared against a benchmark...

  10. Dynamic and failure properties of high damping rubber bearing under high axial stress

    Ishizuka, Hidetake; Murota, Nobuo [Bridgestone Corp., Yokohama (Japan). Yokohama Plant; Fukumori, Takeshi [Bridgestone Corp., Tokyo (Japan). Technical Center

    1995-12-01

    Seismic isolation bearings have been used under axial stresses less than 100(kgf/cm{sup 2}) for many years. If higher axial loads can be applied, however, a larger period shift will be achieved and the size of the isolation devices may be reduced resulting in a cost reduction of the bearing. This paper describes experimental studies of dynamic and failure properties of high damping rubber bearings (HDR) under high axial stress of over 120(kgf/cm{sup 2}) compared with the conventional stress of 65(kgf/cm{sup 2}). The results show that HDR continues to have stable performance under high axial stress with high shear strain. It indicates that high axial stress over 100(kgf/cm{sup 2}) is within the capability of the BDR isolation bearing.

  11. Ball Bearing Analysis with the ORBIS Tool

    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.

  12. Valve assembly having remotely replaceable bearings

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  13. Heuristic explanation of journal bearing instability

    Crandall, S. H.

    1982-01-01

    A fluid-filled journal bearing is viewed as a powerful pump circulating fluid around the annular space between the journal and the bearing. A small whirling motion of the journal generates a wave of thickness variation progressing around the channel. The hypothesis that the fluid flow drives the whirl whenever the mean of the pumped fluid velocity is greater than the peripheral speed of the thickness variation wave is discussed and compared with other simple explanations of journal bearing instability. It is shown that for non-cavitation long bearings the hypothesis predicts instability onset correctly for unloaded bearings but gradually overpredicts the onset speed as the load is increased.

  14. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Yu Lie; R.B. Bhat

    1995-01-01

    The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distri...

  15. Components of bull and bear markets: bull corrections and bear rallies

    Maheu, John M; Thomas H. McCurdy; Yong Song

    2010-01-01

    Existing methods of partitioning the market index into bull and bear regimes do not identify market corrections or bear market rallies. In contrast, our probabilistic model of the return distribution allows for rich and heterogeneous intra-regime dynamics. We focus on the characteristics and dynamics of bear market rallies and bull market corrections, including, for example, the probability of transition from a bear market rally into a bull market versus back to the primary bear state. A Baye...

  16. Chromatographic (TLC) differentiation of grizzly bear and black bear scats

    Picton, Harold D.; Kendall, Katherine C.

    1994-01-01

    While past work concluded that thin-layer chromatography (TLC) was inadequate for the separation of grizzly (Ursus arctos horribilis) and black bear (U. americanus) scats, our study found differences adequate for species separation. A key was constructed using 19 of 40 data points recorded on each(N)=356 profiles of 178) know-species scat. Accuracy was best for late summer scats (94%). Methods for specimen preparation, analysis, and reading the TLC profiles are discussed. Factors involved in scat variation were tested.

  17. A prototype construction of bearing heater system

    A bearing heater system has been successfully constructed using transformer-like method of 1000 VA power, 220 V primary voltage, and 50 Hz electrical frequency. The bearing heater consists of primary coil 230 turns, U type and bar-type iron core with 36 cm2, 9 cm2 ,and 3 cm2 cross-section, and electrical isolation. The bearing heater is used to enlarge the diameter of the bearing so that it can be easily fixed on an electric motor shaft during replacement because the heating is conducted by treated the bearing as a secondary coil of a transformer. This bearing heater can be used for bearing with 3 and 6 cm of inner diameter and 12 cm of maximum outside diameter. (author)

  18. Wave Journal Bearings Under Dynamic Loads

    Hendricks, Robert C.; Dimofte, Florin

    2002-01-01

    The dynamic behavior of the wave journal bearing was determined by running a three-wave bearing with an eccentrically mounted shaft. A transient analysis was developed and used to predict numerical data for the experimental cases. The three-wave journal bearing ran stably under dynamic loads with orbits well inside the bearing clearance. The orbits were almost circular and nearly free of the influence of, but dynamically dependent on, bearing wave shape. Experimental observations for both the absolute bearing-housing-center orbits and the relative bearing-housing-center-to-shaft-center orbits agreed well with the predictions. Moreover, the subsynchronous whirl motion generated by the fluid film was found experimentally and predicted theoretically for certain speeds.

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

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-03-01

    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 genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862

  20. Development and Evaluation of Titanium Spacesuit Bearings

    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

  1. Hydrostatic bearings for a turbine fluid flow metering device

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  2. Conditioning of alpha bearing wastes

    Alpha bearing wastes are generated during the reprocessing of spent fuel, mixed oxide fuel fabrication, decommissioning and other activities. The safe and effective management of these wastes is of particular importance owing to the radiotoxicity and long lived characteristics of certain transuranic (TRU) elements. The management of alpha bearing wastes involves a number of stages which include collection, characterization, segregation, treatment, conditioning, transport, storage and disposal. This report describes the currently available matrices and technologies for the conditioning of alpha wastes and relates them to their compatibility with the other stages of the waste management process. The selection of a specific immobilization process is dependent on the waste treatment state and the subsequent handling, transport, storage and disposal requirements. The overall objectives of immobilization are similar for all waste producers and processors, which are to produce: (a) Waste forms with sufficient mechanical, physical and chemical stability to satisfy all stages of handling, transport and storage (referred to as the short term requirements), and (b) Waste forms which will satisfy disposal requirements and inhibit the release of radionuclides to the biosphere (referred to as the long term requirements). Cement and bitumen processes have already been successfully applied to alpha waste conditioning on the industrial scale in many of the IAEA Member States. Cement systems based on BFS and pozzolanic cements have emerged as the principal encapsulation matrices for the full range of alpha bearing wastes. Alternative technologies, such as polymers and ceramics, are being developed for specific waste streams but are unlikely to meet widespread application owing to cost and process complexity. The merits of alpha waste conditioning are improved performance in transport, storage and disposal combined with enhanced public perception of waste management operations. These

  3. Geobacteraceae strains and methods

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  4. Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

    Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

    2016-01-01

    Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. PMID:26264178

  5. Assay of crystal violet binding for rapid identification of virulent plasmid-bearing clones of Yersinia enterocolitica.

    Bhaduri, S; Conway, L K; Lachica, R V

    1987-01-01

    A rapid, reliable, and simple method based on the binding of crystal violet (CV) is described for differentiating virulence-plasmid-bearing strains of Yersinia enterocolitica from their plasmidless derivatives. As with other plasmid-mediated properties of this organism, the binding of CV occurs at 37 degrees C but not at 25 degrees C. The CV-binding technique provides a simple and efficient means of screening Y. enterocolitica for virulence and for identifying individual plasmid-bearing colon...

  6. Interference Fit Life Factors for Roller Bearings

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

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  7. Stability Analysis of Methane Hydrate-Bearing Soils Considering Dissociation

    Hiromasa Iwai

    2015-06-01

    Full Text Available It is well known that the methane hydrate dissociation process may lead to unstable behavior such as large ground deformations, uncontrollable gas production, etc. A linear instability analysis was performed in order to investigate which variables have a significant effect on the onset of the instability behavior of methane hydrate-bearing soils subjected to dissociation. In the analysis a simplified viscoplastic constitutive equation is used for the soil sediment. The stability analysis shows that the onset of instability of the material system mainly depends on the strain hardening-softening parameter, the degree of strain, and the permeability for water and gas. Then, we conducted a numerical analysis of gas hydrate-bearing soil considering hydrate dissociation in order to investigate the effect of the parameters on the system. The simulation method used in the present study can describe the chemo-thermo-mechanically coupled behaviors such as phase changes from hydrates to water and gas, temperature changes and ground deformation. From the numerical results, we found that basically the larger the permeability for water and gas is, the more stable the simulation results are. These results are consistent with those obtained from the linear stability analysis.

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

    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.

  9. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Yu Lie

    1995-01-01

    Full Text Available The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distribution of journal bearings and the static deflection of the rotor and delays the instability of the system considerably in lateral shaft vibration.

  10. Muscle strain (image)

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  11. Muscle strain treatment

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  12. Bearing Health Assessment Based on Chaotic Characteristics

    Chen Lu

    2013-01-01

    Full Text Available Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM. Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.

  13. Hydrodynamic bearing for light loaded turbo machinery

    The rotor of any turbo-machinery running in journal bearings is prone to two types of well-known vibrations. Synchronous Vibrations occur due to run out or forces resulting from unbalancing of the shaft. Sub synchronous vibrations are more serious, this phenomenon is commonly associated with oil film forces of the journal bearing. In order to avoid sub synchronous vibrations, different types of journal bearings having helical grooves were investigated both theoretically and experimentally. (author)

  14. Probabilistic Aspect of Rolling Bearings Durability

    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...

  15. A miniature tilting pad gas lubricated bearing

    Sixsmith, H.; Swift, W. L.

    1983-12-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  16. Bearing fault diagnosis based on vibration signals.

    Abdusslam, S.A.; Gu, Fengshou; Ball, Andrew

    2009-01-01

    The vibration signal obtained from operating machines contains information relating to machine condition as well as noise. Further processing of the signal is necessary to elicit information particularly relevant to bearing faults. Many techniques have been employed to process the vibration signals in bearing faults detection and diagnosis. Two common techniques, time domain techniques and frequency domain techniques are used in this paper to investigate bearings condition.

  17. Numerical simulations of rubber bearing tests and shaking table tests

    Test data concerning rubber bearing tests and shaking table tests of base-isolated model conducted by CRIEPI are provided to the participants of Coordinated Research Program (CRP) on 'Intercomparison of Analysis Methods for predicting the behaviour of Seismically Isolated Nuclear Structure', which is organized by International Atomic Energy Agency (IAEA), for the comparison study of numerical simulation of base-isolated structure. In this paper outlines of the test data provided and the numerical simulations of bearing tests and shaking table tests are described. Using computer code ABAQUS, numerical simulations of rubber bearing tests are conducted for NRBs, LRBs (data provided by CRIEPI) and for HDRs (data provided by ENEA/ENEL and KAERI). Several strain energy functions are specified according to the rubber material test corresponding to each rubber bearing. As for lead plug material in LRB, mechanical characteristics are reevaluated and are made use of. Simulation results for these rubber bearings show satisfactory agreement with the test results. Shaking table test conducted by CRIEPI is of a base isolated rigid mass supported by LRB. Acceleration time histories, displacement time histories of the isolators as well as cyclic loading test data of the LRB used for the shaking table test are provided to the participants of the CRP. Simulations of shaking table tests are conducted for this rigid mass, and also for the steel frame model which is conducted by ENEL/ENEA. In the simulation of the rigid mass model test, where LRBs are used, isolators are modeled either by bilinear model or polylinear model. In both cases of modeling of isolators, simulation results show good agreement with the test results. In the case of the steel frame model, where HDRs are used as isolators, bilinear model and polylinear model are also used for modeling isolators. The response of the model is simulated comparatively well in the low frequency range of the floor response, however, in

  18. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL)

  19. Bear Capture. Research, and Request for Consideraton of Releases of Bears at Dahomey NWR in 1996

    US Fish and Wildlife Service, Department of the Interior — A series of memos and correspondences concerning the capture of a bear in Cleveland, MS and release on Dahomey NWR along with graduate research on bears from...

  20. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  1. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  2. Long-term bearing wear tests of conventional journal bearings and development of hydrostatic bearings for the LOFT drag-disc turbine transducer

    The details of a two-year development program concerning materials for use as turbine bearings in a pressurized water reactor environment are reported. Two types of bearings have been examined, both conventional journal bearings and hydrostatic bearings. The results of long-term bearing wear tests conducted at 590 K and 15.1 MPa in water are presented. The feasibility of using hydrostatic bearings for the same transducer is demonstrated

  3. Living in Bear Country: increasing municipal compliance with the Bear Smart Program in British Columbia

    Hamilton, Anthony David

    2011-01-01

    Many communities in British Columbia are grappling with the presence of bears in their communities. The Ministry of Environment (MOE) created the Bear Smart Program in 2002 to assist these communities to prevent human-bear conflict. However, at the end of 2010 only two communities have completed the program. This study draws upon informant interviews and local documentation to develop a better understanding of why communities are participating but not completing the Bear Smart Program. Th...

  4. Journal bearing performance and metrology issues

    S. Sharma

    2009-01-01

    Full Text Available Purpose: In this paper, a radial clearance of a journal bearings and the metrology of the radial clearance measurement is described.Design/methodology/approach: In this experimental study out-of-roundness and radial clearance of journal bearings were measured with high precision and the impact of their metrology was examined on the specific oil film thickness of the bearing. Some metrological issues were emerged and these should be taken into account when bearings are designed.Findings: An investigation showed that the radial clearance measurements can vary from one measuring device to another and the specified clearance may not necessarily meet the design criteria of specific oil film thickness. The study indicates that the radial clearance measurement can differ from one measuring device to another depending upon the precision that can be achieved by the device. The radius of the bearing or the shaft also varies along the circumference, mainly due to out-of-roundness. The out-of-roundness contributes to the error in radial clearance measurement and hence similar to the cut off length specified with the surface roughness, the out-of-roundness needs to be specified with the radial clearance.Practical implications: The radial clearance of a journal bearing is a key design parameter and bearing performance mainly depends upon this parameter. In this paper was showed that the metrology of the radial clearance measurement plays a significant role and not only that the bearing manufacturer or the user of the bearing is aware of this fact but the bearing designer must also take this fact into account while designing bearingsOriginality/value: This paper showed that The radial clearance is a sensitive micro-geometry parameter and hence metrology plays a vital role in making decisions

  5. Mechanical behaviour of Bioactive Glass granules and morselized cancellous bone allograft in load bearing defects.

    Hulsen, D J W; Geurts, J; van Gestel, N A P; van Rietbergen, B; Arts, J J

    2016-05-01

    Bioactive Glass (BAG) granules are osteoconductive and possess unique antibacterial properties for a synthetic biomaterial. To assess the applicability of BAG granules in load-bearing defects, the aim was to compare mechanical behaviour of graft layers consisting of BAG granules and morselized cancellous bone allograft in different volume mixtures under clinically relevant conditions. The graft layers were mechanically tested, using two mechanical testing modalities with simulated physiological loading conditions: highly controllable confined compression tests (CCT) and more clinically realistic in situ compression tests (ISCT) in cadaveric porcine bone defects. Graft layer impaction strain, residual strain, aggregate modulus, and creep strain were determined in CCT. Graft layer porosity was determined using micro computed tomography. The ISCT was used to determine graft layer subsidence in bone environment. ANOVA showed significant differences (p<0.001) between different graft layer compositions. True strains absolutely decreased for increasing BAG content: impaction strain -0.92 (allograft) to -0.39 (BAG), residual strain -0.12 to -0.01, and creep strain -0.09 to 0.00 respectively. Aggregate modulus increased with increasing BAG content from 116 to 653MPa. Porosity ranged from 66% (pure allograft) to 15% (pure BAG). Subsidence was highest for allograft, and remarkably low for a 1:1 BAG-allograft volume mixture. Both BAG granules and allograft morsels as stand-alone materials exhibit suboptimal mechanical behaviour for load-bearing purpose. BAG granules are difficult to handle and less porous, whereas allograft subsides and creeps. A 1:1 volume mixture of BAG and allograft is therefore proposed as the best graft material in load-bearing defects. PMID:26972764

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

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

    2015-01-01

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

  7. Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

    Thomsen, Kim; Klit, Peder

    2012-01-01

    bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas the...

  8. Phylogeography of mitochondrial DNA variation in brown bears and polar bears

    Shields, Gerald F.; Adams, Deborah; Garner, Gerald; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

    2000-01-01

    We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

  9. Methods and systems for micro bearings

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  10. Can polar bear hairs absorb environmental energy?

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  11. 33 CFR 117.543 - Bear Creek.

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the...

  12. Friction coefficients of PTFE bearing liner

    Daniels, C. M.

    1979-01-01

    Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

  13. Movie Director Bags a Silver Bear

    2008-01-01

    Chinese director and film writer Wang Xiaoshuai has walked away with the Silver Bear award at the 58th Berlin International Film Festival for best script of Zuo You, or In Love We Trust. Back in 2001, Wang won his first Silver Bear award for directing Beijing

  14. Shaft Center Orbit in Dynamically Loaded Bearings

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this method...... over the years. In 1966 Jorgen W. Lund [5]published an approach to ¯nd the dynamic coe±cients of a journal bearing by a ¯rst order perturbation of the Reynold's equation. These coe±cients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coe±cients of the bearing could be used to ¯nd the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for ¯nding the damping coe±cients in this work, but the...

  15. Experimental investigations of active air bearings

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    greatest challenges in a high-speed gas bearing design. A great deal of research is devoted to attack such issues, where most propose passive designs such as compliant foil bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic......Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread of...

  16. Program Calibrates Strain Gauges

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

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

    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...

  18. Dynamic load testing on the bearing capacity of prestressed tubular concrete piles in soft ground

    Yu, Chuang; Liu, Songyu

    2008-11-01

    Dynamic load testing (DLT) is a high strain test method for assessing pile performance. The shaft capacity of a driven PTC (prestressed tubular concrete) pile in marine soft ground will vary with time after installation. The DLT method has been successfully transferred to the testing of prestressed pipe piles in marine soft clay of Lianyungang area in China. DLT is investigated to determine the ultimate bearing capacity of single pile at different period after pile installation. The ultimate bearing capacity of single pile was founded to increase more than 70% during the inventing 3 months, which demonstrate the time effect of rigid pile bearing capacity in marine soft ground. Furthermore, the skin friction and axial force along the pile shaft are presented as well, which present the load transfer mechanism of pipe pile in soft clay. It shows the economy and efficiency of DLT method compared to static load testing method.

  19. Modulation of allele leakiness and adaptive mutability in Escherichia coli

    R. Jayaraman

    2000-08-01

    It is shown that partial phenotypic suppression of two ochre mutations (argE3 and lacZU118) and an amber mutation (in argE) by sublethal concentrations of streptomycin in an rpsL+ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection. Streptomycin also increases adaptive mutability brought about by the ppm mutation described earlier. Inactivation of recA affects neither phenotypic suppression by streptomycin nor replication-associated mutagenesis but abolishes adaptive mutagenesis. These results indicate a causal relationship between allele leakiness and adaptive mutability.

  20. Genomic sequencing of Pleistocene cave bears

    Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot; Krause, Johannes; Detter, J. Chris; Paabo, Svante; Rubin, Edward M.

    2005-04-01

    Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.

  1. Passive Magnetic Bearing With Ferrofluid Stabilization

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  2. Intelligent monitoring of ball bearing conditions

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

    1992-09-01

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

  3. Design of gas bearing systems for precision applications

    Wang, Junming

    Research to provide the up to date knowledge and efficient tools to design better Externally Pressurized Gas (EPG) bearing systems, including the design of individual bearings, and to arrange all the bearings used in an optimal way is reported. Both circular and rectangular EPG pads with rigid bearing surfaces and rigid inlet restrictors were used. The following topics closely related to the applications in precision engineering are discussed: influences of gap shape on the bearing performance; effects of bearing body tilt on the bearing performance; influences of bearing surface imperfections on bearing performance; temperature drops in EPG bearings in quasistationary conditions; the optimal use of multiple bearings in a mechanical system; the use of EPG bearing damping characteristics in the design; and the effects of motion velocity.

  4. Future bearing surfaces in total hip arthroplasty.

    Chang, Jun-Dong

    2014-03-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements

  5. Hot deformation behaviors and flow stress model of GCr15 bearing steel

    LIAO Shu-lun; ZHANG Li-wen; YUE Chong-xiang; PEI Ji-bin; GAO Hui-ju

    2008-01-01

    The hot deformation behaviors of GCr15 bearing steel were investigated by isothermal compression tests, performed on a Gleeble-3800 thermal-mechanical simulator at temperatures between 950℃ and 1 150 ℃ and strain rates between 0.1 and 10s-1.The peak stress and peak strain as functions of processing parameters were obtained. The dependence of peak stress on strain rate and temperature obeys a hyperbolic sine equation with a Zener-Hollomon parameter. By regression analysis, in the temperature range of 950-1150℃ and strain rate range of 0.1-10 s-1, the mean activation energy and the stress exponent were determined to be 351kJ/mol and 4.728, respectively. Meanwhile, models of flow stress and dynamic recrystallization (DRX) grain size were also established. The model predictions show good agreement with experimental results.

  6. Constitutive Models for Debris-bearing Ice Layers

    Moore, P. L.

    2013-12-01

    Rock debris is incorporated within many glaciers and ice sheets, particularly in basal ice layers and englacial debris bands. Field observations and laboratory experiments have shown that debris inclusions can both strengthen and weaken ice by as much as two orders of magnitude compared to debris-free ice under the same conditions. Nevertheless, models of glacier flow usually neglect any effect of debris-bearing layers. Where debris-bearing ice is present, proper treatment of its deformation could profoundly impact model results. A three-phase mechanical model is presented that reproduces many of the key observations of debris-bearing ice rheology. First order variables in the model are limited to debris concentration, particle size, solute concentration and temperature. At low debris concentrations (less than about 40% by volume), the mixture is treated under the framework of a dispersion-strengthened metal alloy but with a fluidity that is enhanced by premelted water at ice-debris interfaces. While debris strengthens the ice by interfering with the motion of dislocations, thermally-activated detachment can reduce the effect at temperatures close to melting. At these warm temperatures, recovery aided by unfrozen interfacial water acts to weaken the mixture, an effect that is further ehnanced by the presence of solutes at particle surfaces. Whether the debris-bearing ice is stronger or weaker than debris-free ice in the model depends strongly on the specific surface area of the debris and on a parameter that describes the thermal detachment of dislocations. As debris concentrations exceed about 40%, dispersion-strengthened ice flow still governs bulk deformation but the effective viscosity is further increased by enhanced strain rates in the ice "matrix" as the average inter-particle distance declines. At still higher concentrations (greater than about 52% by volume for sand), deformation is primarily frictional. The mixture is thus treated as a dilatant Coulomb

  7. Compressor ported shroud for foil bearing cooling

    Elpern, David G.; McCabe, Niall; Gee, Mark

    2011-08-02

    A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.

  8. Corporate risks, risk bearing ability and equity

    Handschin, Lukas

    2011-01-01

    There is a relation between corporate risks, risk bearing ability and equity. In order to assess the risk bearing ability of a corporation, one reference figure is equity, understood as the sum of legal capital and reserves, free reserves and accrued profits. Equity shows the risk bearing ability related to the risk of asset reduction as well as the ability of the corporation to attract new liquidity by increasing debts, in case of a negative free cash flow. Equity is the risk reserve of the ...

  9. Hydrostatic, aerostatic and hybrid bearing design

    Rowe, W Brian

    2012-01-01

    Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: Clear e

  10. Microeconomic analysis of military aircraft bearing restoration

    Hein, G. F.

    1976-01-01

    The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

  11. Rotor Vibration Reduction via Active Hybrid Bearings

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement with...

  12. Bear bile: dilemma of traditional medicinal use and animal protection

    Nagamatsu Tadashi; Tsao Sai-Wah; Ng Kwan-Ming; Wang Ning; Siu Kayu; Feng Yibin; Tong Yao

    2009-01-01

    Bear bile has been used in Traditional Chinese Medicine (TCM) for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Techn...

  13. A study on nonlinear finite element analysis of laminated rubber bearings. Pt.1. Development of evaluation method for mechanical properties of laminated rubber bearings for horizontal base isolation system considering volumetric deformation of rubber material

    The purpose of this research is to develop the evaluation method for mechanical properties of laminated rubber bearings by nonlinear finite element method (FEM) considering the volumetric deformation of natural rubber material. Relationship between pressure and volumetric strain of the natural rubber is obtained from the volumetric tests and is introduced into user-subroutine of the FEM code (ABAQUS). Finite element analyses of natural rubber bearings (NRB) and the natural rubber bearing with lead plug (LRB) are carried out. The results may be summarized as follows; 1) Horizontal, vertical stiffness and effect of shear deformation on vertical stiffness of natural rubber bearings that have various shape are simulated with enough accuracy. 2) Horizontal and vertical stiffness of LRB are also simulated well. (author)

  14. Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

    Amin Keshavarz; Abdoreza Fazeli; Siavosh Sadeghi

    2016-01-01

    In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided...

  15. Static and dynamic bearing capacity of strip footings, under variable repeated loading

    ARVIN, Mohammad Reza; ASKARI, Faradjollah; Farzaneh, Orang

    2012-01-01

    The problem of bearing capacity of strip footings is one of the basic and classical problems of geotechnical engineering. Footings under variable repeated loads are vulnerable to collapse due to accumulation of plastic strains or inadaptation. Unlike common limit state methods, the shakedown method can be applied to investigate the behavior of structures subjected to loads varying and repeating in time. In the present study, shakedown theory is employed to determine the static and dy...

  16. Experimental evaluation of mechanical property for lead rubber bearing

    In these days, the basic isolation system is often used to improve the seismic capacity of the structures instead of conventional techniques of strengthening the structural members. The purpose of this study is to evaluate dynamic properties and mechanical characteristics of the 10 tonf-LRB(Lead-Rubber Bearing). Experimental studies were performed to obtain the hysteretic behavior, effective shear stiffness (Keff), equivalent damping (Heq), capacity of energy dissipation (WD) of six 10tons-LRB. Especially, in this study, the response of the LRB for high loading frequency(0.5Hz∼3.0Hz) was estimated. The effective shear stiffness of the LRB decrease and the capacity of energy dissipation increases as the shear strain amplitude increase. But the shear behavior of the LRB is not affected sensitivity by loading frequency

  17. Transient unbalance response of four multilobe journal bearings

    Allaire, P. E.; Li, D. F.; Choy, K. C.

    1979-01-01

    This work carries out an analysis of the transient response of four multilobe journal bearings (elliptical, offset, three-lobe, and four-lobe) subject to unbalance both below and above the linearized stability thresholds for the bearings. It extends the work of a previous paper on a balanced rotor in the same four bearing types. Transient orbits, bearing forces, and a numerical fast Fourier transform analysis of the orbits are presented. A comparison of bearing forces above the stability threshold for each bearing indicates that the elliptical bearing has the most violent whirl vibration amplitudes, while the offset bearing exhibits the least amount of subsynchronous vibration.

  18. Unconventional Bearing Capacity Analysis and Optimization of Multicell Box Girders

    Jovan Tepic

    2014-01-01

    Full Text Available This study deals with unconventional bearing capacity analysis and the procedure of optimizing a two-cell box girder. The generalized model which enables the local stress-strain analysis of multicell girders was developed based on the principle of cross-sectional decomposition. The applied methodology is verified using the experimental data (Djelosevic et al., 2012 for traditionally formed box girders. The qualitative and quantitative evaluation of results obtained for the two-cell box girder is realized based on comparative analysis using the finite element method (FEM and the ANSYS v12 software. The deflection function obtained by analytical and numerical methods was found consistent provided that the maximum deviation does not exceed 4%. Multicell box girders are rationally designed support structures characterized by much lower susceptibility of their cross-sectional elements to buckling and higher specific capacity than traditionally formed box girders. The developed local stress model is applied for optimizing the cross section of a two-cell box carrier. The author points to the advantages of implementing the model of local stresses in the optimization process and concludes that the technological reserve of bearing capacity amounts to 20% at the same girder weight and constant load conditions.

  19. Strains and Sprains

    ... ON THIS TOPIC Sports Medicine Center Preventing Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken ... Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries Groin Strain Ankle Sprains Strains and Sprains Stretching ...

  20. Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

    Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

    2014-01-01

    We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears. PMID:24477675

  1. All Polar Bear Critical Habitat Combined

    US Fish and Wildlife Service, Department of the Interior — This layer shows all categories of polar bear critical habitat combined into one overall polygon. This polygon includes the following critical habitat types: 1)...

  2. Telemetry techniques used on Kodiak brown bear

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a study on the techniques used to monitor the movements of Kodiak brown bears instrumented with radio transmitters. Methods...

  3. Bear Lake-Minidoka - Phragmites Control

    US Fish and Wildlife Service, Department of the Interior — Bear Lake: Phragmites patches were sprayed on the refuge & north of the lake proper. Minidoka: patches along the Snake River & Lake Walcott were treated...

  4. Mercury biomagnification in polar bears ( Ursus maritimus)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  5. LIGHT-WEIGHT LOAD-BEARING STRUCTURE

    2009-01-01

    the core (3) of strong concrete. The invention also relates to a method of casting of light-weight load-bearing structures (1) with optimized compression zone (2) where one or more channels, grooves, ducts, pipes and/or hoses (5) formed in the load-bearing structure (1) serves as moulds for moulding......The invention relates to a light-weight load-bearing structure (1) with optimized compression zone (2), where along one or more compression zones (2) in the structure (1) to be cast a core (3) of strong concrete is provided, which core (3) is surrounded by concrete of less strength (4) compared to...... one or more cores (3) of strong concrete in the light-weight load-bearing structure (1)....

  6. Ceramic Rail-Race Ball Bearings

    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

  7. Novel nano bearings constructed by physical adsorption

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  8. Cavitation Peening of Aerospace Bearings Project

    National Aeronautics and Space Administration — High-value bearings are a critical part of the safety, reliability, cost and performance of modern aircraft. A typical passenger jet will have 100 to 175 high-valve...

  9. Polar bear research in Alaska, spring 1982

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  10. Polar bear research in Alaska, spring 1981

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  11. The polar bear and its protection

    US Fish and Wildlife Service, Department of the Interior — No census has been made of the polar bear population and indeed the general movements of the animals within their range are poorly known. At present it is not...

  12. Bearings for the HFIR control plates

    Recent accelerated wear of HFIR bearings seems to be a more advanced stage of the situation encountered in 1967. The latest observations are in agreement with the hypothesis that high-frequency impact loads at a 300 angle on these bearings are the apparent basic cause of their short life. In view of the limited possibilities for change at this stage of HFIR operation, the region of best payoff seems to be an increase in the load-carrying area at some acceptable sacrifice of low rolling friction. On this basis three types of bearings are proposed for test--two of these are journal types and one is a slider type. The next planned shutdown for major parts replacement provides an opportunity to test these modified bearing types in the HFIR under full mechanical operating conditions but without nuclear operation. The program is recommended for consideration and adoption. (U.S.)

  13. Gauge Measures Large Spherical Bearing Surfaces

    Davis, George L.

    1992-01-01

    Radius of spherical portion of surface computed from reading of depth gauge. Measuring tool calibrated by applying it to reference spherical surface of known radius. Used onsite, so unnecessary to ship bearings to laboratory for examination by computerized test equipment.

  14. Strained Silicon Photonics

    Wehrspohn, Ralf B; Jörg Schilling; Christian Bohley; Clemens Schriever

    2012-01-01

    A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is inves...

  15. Analysis of bearing capacity of CA corner wall in AP1000 nuclear power plant

    Background: The module construction technology is widely used in the AP1000 nuclear power plant. The CA structural module in the containment building is important for the safety of the nuclear power plant, the corner wall of the CA structural is critical under load, so it is important to do research on bearing capacity of CA corner wall. Purpose: Finite element analysis model of the CA comer wall is conducted in the ABAQUS software to study the bearing capacity and the stress/strain state of the CA comer' wall under different load cases. Methods: Finite element analysis model considering the material nonlinearity, contact nonlinearity and geometric nonlinearity conducted in the ABAQUS software is used for the analysis of the CA corner wall. Results: The ultimate bearing capacities of the CA comer wall in different loads are studied, and the study also gets the load-displacement curves. The bearing capacities of CA corner wall under different axial loads are also studied in this paper. The influence of ultimate bearing capacities of CA comer wall is founded out if the steel and concrete work together. Conclusions: When the CA corner wall subjects to the bending load, the failure part of the CA corner wall is the corner core concrete. When the CA corner wall subjects to the shear load, the failure part of the CA corner wall is the straight module wall. The axial load has notable influence on the capacity of CA corner wall. (authors)

  16. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. PMID:26803551

  17. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus).

    Cronin, Matthew A; MacNeil, Michael D

    2012-01-01

    Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. We used previously published genotype data for 8 microsatellite DNA loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life-history characteristics that distinguish polar bears and brown bears as different species with little or no gene flow among extant populations. PMID:23125409

  18. Spectral properties and identification of aerostatic bearings

    Jan Kozánek; Ladislav P(u)st

    2011-01-01

    Modified rotor kit BentlyNevada was used for dynamic characteristics measurements of new developed aerostatic bearings. Mathematical model of these bearings is considered as linear. Model was identified with the help of harmonic force excitation independently from the speed of journal rotation. The stiffness and damping matrices were identified for different air inlet pressures. The calculated spectral properties allow to determine the stability boundary for suitable variation of model parameters.

  19. Flywheel energy storage with superconductor magnetic bearings

    Weinberger, Bernard R.; Lynds, Jr., Lahmer; Hull, John R.

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  20. Partial Lubrification of Full Cylindrical Bearings

    Capriz, Gianfranco; Cimatti, Giovanni

    1981-01-01

    the phenomenon of cavitation in bearings is often studied under the assumption that the pressure and the pressure gradient both vanish along the unknown boundary of the cavitation bubble. However, such conditions (often namend after Swift and Stieber) may be inconsistent with mass conservation. The discrepancy is particularly striking when the case of long bearings is studied within the so called Sommerfeld approximation. Therefore a complete analysis of the Sommerfeld case is carried out her...

  1. Surface layer characterisation of bearing rings

    S.J. Skrzypek; M. Goły

    2007-01-01

    austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in bearing rings and following measurements of residual stresses were carried out as well. The bearing elements were made of 100Cr6 steel and they were smoothed and grinded.Design/methodology/approach: Particular features of diffraction patterns like angle position; shape and intensity are used to characterize phase composition, residual micro and macro-stresses, crystallographic tex...

  2. Design of bearing structures of dwelling - house

    Sodja, Urška

    2007-01-01

    Graduation thesis represents design of bearing structures of dwelling-house including materials and materials´ properties of bearing structures. Self weight, imposed load, snow, and wind are determinated regarding EC1. Static calculation of building is divided to design of timber, reinforced concrete elements and control of resistance of walls. Summary contains earthquake rules for simple masonry buildings. Enclosure contains plans for positions of slaps and reinforces.

  3. Lesiones macro y microscópicas de intestino delgado de cerdos neonatos sin calostrar inoculados experimentalmente con cepas de E. coli fimbriadas Histopatholocial lesions in the small intestine of calostrum deprived pigs inoculated with strains of E. Coli bearing F4, F5, F6 y F41 fimbriaes

    A.M CANAL

    1999-01-01

    Full Text Available La presente investigación se realizó con el propósito de evaluar los efectos patológicos de cepas enteropatógenas de E. coli que expresan antígenos fimbriales F4, F5, F6 y F41, administradas oralmente a cerdos neonatos que no ingirieron calostro. Los cerdos inoculados experimentalmente con las cuatro cepas enteropatógenas de E. coli presentaron diarrea acuosa y de color amarilla a las 4 h.p.i. Las lesiones macroscópicas se caracterizaron por congestión y abundante contenido acuoso, apreciándose diferencias solo en la intensidad lesional entre los diferentes grupos inoculados. Microscópicamente, el íleon fue el segmento más afectado, observándose congestión, adherencia bacteriana, vacuolización epitelial de las vellosidades intestinales, atrofia, infiltrados de neutrófilos y necrosis linfoide en placas de Peyer, siendo la cepa E. coli F4 responsable de las lesiones de mayor severidad. Los resultados de la presente investigación confirman la importancia de los antígenos fimbriales como factor de adhesión de cepas enteropatógenas de E. coli al intestino delgado de cerdos lactantes y permite proyectar a futuro metodologías que utilicen las propiedades antigénicas de las fimbrias no solo como métodos de diagnóstico sino también en la elaboración de inmunógenos los cuales evitarían la adhesión bacteriana y la presentación de cuadros de colibacilosis, enfermedad responsable de cuantiosas pérdidas económicas en la explotación porcina en la actualidadA study to evaluate the degrees of lesions caused by different enteropathogenic strains of E. coli was carried out. Newborn piglets without calostrum were innoculated with enteropathogenic strains of E. coli which contained F4, F5, F6 and F41 fimbriae in order to characterize the macro and microscopic lesions to the duodenum, jejunum and ilium. The pigs experimentally innoculated with the four enteropathegenic strains of E. coli presented watery, yellowish diarrhea four

  4. Rotordynamics and bearing design of turbochargers

    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.

  5. Protection of Escherichia coli cells against the lethal effects of ultraviolet and X-irradiation by prior X-irradiation

    When log phase cells of wild-type E.coli K-12 were maintained in growth medium after X-irradiation, they became progressively more resistant to a subsequent exposure to UV or X-radiation. The time to achieve maximum resistance was about 60 min. The uvrB, uvrD, polA and certain exrA strains (W3110 background) also demonstrated this X-ray-induced resistance to subsequent UV or X-irradiation but recA, recB, lex (AB1157 or W3110 backgrounds) and other exrA strains (AB1157 background) did not. The resistance induced in wild-type, uvrB and uvrD cells was characterized by the production or enhancement of a shoulder on the survival curves obtained for the second irradiation, while the resistance induced in the W3110 exrA strains was expressed only as a change in slope. The induction of resistance in the W3110 exrA strain was not inhibited by the presence of chloramphenical, but that in the wild-type cells appeared to be. The production or enhancement of a shoulder on the survival curves of the rec+ lex+ exr+ cells is consistent with the concept of the radiation induction of repair enzymes. Alternative explanations, however, are discussed. (author)

  6. Rolling Bearing Life Prediction, Theory, and Application

    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.

  7. A circumpolar monitoring framework for polar bears

    Vongraven, Dag; Aars, Jon; Amstrup, S.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Mike; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

    2012-01-01

    Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

  8. 49 CFR 230.102 - Tender plain bearing journal boxes.

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  9. Noise reduction of rotating machinery by viscoelastic bearing supports

    Tillema, Hetzer Gido

    2003-01-01

    The demand for silent rolling bearing applications, such as electric motors and gearboxes, has resulted in an investigation of viscoelastic bearing supports. By placing a thin viscoelastic layer between the bearing outer ring and the surrounding structure, vibrations of the shaft-bearing arrangement

  10. Severity estimation of cracked shaft vibrations within fluid film bearings

    Prabhu, B. S.; Sekhar, A. S.

    1995-07-01

    The equations of motion, with four degrees of freedom, taking into consideration the flexibility, damping and cross coupling of the fluid film bearings are derived for a cracked Jeffcott rotor supported on fluid film bearings. Dimensionless equations are developed for dynamic radial load, dynamic pressure developed in the fluid film bearings and coefficient of dissipation considering the journal vibrations in two harmonics; bearing fluid film stiffness and damping coefficients. These are applied to a cracked Jeffcott rotor supported on different types of bearings, i.e., cylindrical journal bearings, offset cylindrical bearings, tilting pad journal bearings and three-lobe bearings. Based on the allowable dynamic pressure developed in the fluid bearings, the severity of cracked shaft and allowable crack depths are estimated in this study. Measurement of dynamic pressure and dissipation for monitoring the crack growth is suggested. However, 2x vibration is the best indicator of cracks in the shafts.

  11. Bearing assemblies, apparatuses, and motor assemblies using the same

    Sexton, Timothy N.; Cooley, Craig H.; Knuteson, Cody W.

    2015-12-29

    Various embodiments of the invention relate to bearing assemblies, apparatuses and motor assemblies that include geometric features configured to impart a selected amount of heat transfer and/or hydrodynamic film formation. In an embodiment, a bearing assembly may include a plurality of superhard bearing pads distributed circumferentially about an axis. At least some of the plurality of superhard bearing pads may include a plurality of sub-superhard bearing elements defining a bearing surface. At least some of the plurality of sub-superhard bearing elements may be spaced from one another by one or more voids to impart a selected amount of heat transfer and hydrodynamic film formation thereon during operation. The bearing assembly may also include a support ring that carries the plurality of superhard bearing pads. In addition, at least a portion of the sub-superhard bearing elements may extend beyond the support ring.

  12. Rotor-Bearing System Stability Performance Comparing Hybrid versus Conventional Bearings

    Gomez-Mancilla Julio

    2005-01-01

    Full Text Available New closed-form expressions for calculating the linear stability thresholds for rigid and flexible Jeffcott systems and the imbalance response for a rotor supported on a hybrid bearing are presented. For typical bearings characteristics, expressions yield stability thresholds practically equal to those reported by Lund (1966. The hybrid bearing design has a single injection port whose location is so chosen to stabilize the bearing performance and to reduce the steady equilibrium attitude angle. Rotordynamics coefficients graphs for conventional and pressurized bearings, as functions of bearing equilibrium eccentricity and/or Sommerfeld number, are presented. Using the rotordynamics coefficients into the expressions for the corresponding velocity thresholds and the imbalance response, the system stability and vibration performances are estimated and analyzed. When comparing the Jeffcott flexible shaft supported on two journal bearings of the conventional type with the hybrid type, the results show a clear superiority of the pressurized design as far as stability behavior is concerned. Specifically for cases of flexible shafts with similar characteristics to those used in industry, the analysis shows that this design yields velocity thresholds 25%–40% higher compared to the conventional circular ones. Also this bearing displays nonlinear feeding pressure behavior, and it is capable of reducing the synchronous vibration amplitude in most speed ranges, except around the critical speed; moreover, for certain Jeffcott configurations the amplitude reduction can be substantial.

  13. 77 FR 59639 - Bear Lake National Wildlife Refuge, Bear Lake County, ID and Oxford Slough Waterfowl Production...

    2012-09-28

    ... notice in the Federal Register (75 FR 35829; June 23, 2010). Bear Lake National Wildlife Refuge Bear Lake... Fish and Wildlife Service Bear Lake National Wildlife Refuge, Bear Lake County, ID and Oxford Slough... our draft comprehensive conservation plan and environmental assessment (Draft CCP/EA) for the...

  14. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace Mechanism Applications

    DellaCorte, Christopher; Noebe, Ronald D.; Stanford, Malcolm; Padula, Santo A.

    2011-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hard materials to minimize wear and attain long life. In such components, heavily loaded contact points (e.g., meshing gear teeth, bearing ball-raceway contacts) experience high contact stresses. The combination of high hardness, heavy loads and high elastic modulus often leads to damaging contact stress. In addition, mechanical component materials, such as tool steel or silicon nitride exhibit limited recoverable strain (typically less than 1 percent). These material attributes can lead to Brinell damage (e.g., 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 paper, a superelastic alloy, 60NiTi, is considered for rolling element bearing applications. A series of Rockwell and Brinell hardness, compressive strength, fatigue and tribology tests are conducted and reported. The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to bearings largely impervious to shock load damage. It is anticipated that bearings and components made from alloys with such attributes can alleviate many problems encountered in advanced aerospace applications.

  15. Fatigue Life Analysis of Rolling Bearings Based on Quasistatic Modeling

    Wei Guo; Hongrui Cao; Zhengjia He; Laihao Yang

    2015-01-01

    Rolling bearings are widely used in aeroengine, machine tool spindles, locomotive wheelset, and so forth. Rolling bearings are usually the weakest components that influence the remaining life of the whole machine. In this paper, a fatigue life prediction method is proposed based on quasistatic modeling of rolling bearings. With consideration of radial centrifugal expansion and thermal deformations on the geometric displacement in the bearings, the Jones’ bearing model is updated, which can pr...

  16. An Advanced Microturbine System with Water-Lubricated Bearings

    Susumu Nakano; Tadaharu Kishibe; Tomoaki Inoue; Hiroyuki Shiraiwa

    2009-01-01

    A prototype of the next-generation, high-performance microturbine system was developed for laboratory evaluation. Its unique feature is its utilization of water. Water is the lubricant for the bearings in this first reported application of water-lubricated bearings in gas turbines. Bearing losses and limitations under usage conditions were found from component tests done on the bearings and load tests done on the prototype microturbine. The rotor system using the water-lubricated bearings ach...

  17. Noise reduction of rotating machinery by viscoelastic bearing supports

    Tillema, Hetzer Gido

    2003-01-01

    The demand for silent rolling bearing applications, such as electric motors and gearboxes, has resulted in an investigation of viscoelastic bearing supports. By placing a thin viscoelastic layer between the bearing outer ring and the surrounding structure, vibrations of the shaft-bearing arrangement can be isolated and damped in such a way that the radiated sound power is reduced. The ultimate goal of this research was to develop a design strategy for viscoelastic bearing supports resulting i...

  18. Method for changing removable bearing for a wind turbine generator

    Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Scotia, NY), Gadre; Aniruddha Dattatraya (Rexford, NY)

    2008-04-22

    A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

  19. Assessing bear-human conflicts in the Yukon Territory

    Lukie, Raechel Dawn

    2010-01-01

    Managing conflicts between bears and humans is vital for human safety and for the conservation of bears. This study investigated black bear (Ursus americanus) and grizzly bear (Ursus arctos) interactions with humans in 18 major communities of the Yukon Territory. I used an information theoretic approach to generate predictive models of the relative potential of bear-human interaction for the 9 conservation officer management regions in the Yukon Territory. I independently modeled interactions...

  20. Vascular injuries after bear attacks: Incidence, surgical challenges and outcome

    Wani Mohd; Ahangar Abdul; Lone Gh; Lone Reyaz; Ashraf Hakeem; Dar Abdul; Bhat M; Singh Shyam; Bijli Akram; Irshad Ifat

    2011-01-01

    Background : Bear mauling is rarely reported in medical literature due to its rare occurrence. Present study was undertaken to describe the pattern and management of bear maul vascular injuries in Kashmir. Methods : Study of patients with bear maul vascular injury from 1st Jan 2004 to 31st Dec. 2008. Fifteen patients with bear maul vascular injury were studied. All patients of bear maul without vascular injury were excluded from the study. Results : Most of the patients were treated by revers...

  1. Aerial strip surveys of polar bears in the Barents Sea

    Wiig, Øystein; Bakken, Vidar

    1990-01-01

    Aerial strip surveys of polar bears in the Barents Sea were performed by helicopter in winter 1987. The number of bears within 100 m on each side of the helicopter was counted. A total of 263.6 km2 was surveyed and 21 bears were counted. Most of the bears were found in the southern part of the area, which indicates that the southwestern ice edge area in the Barents Sea is a very important winter habitat for polar bears.

  2. ES and H-compatible lubrication for duplex bearings

    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.

  3. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  4. Pipe and elbow ratcheting strain effects on predicted fatigue failure

    Pipe and elbow ratcheting strains and their effects on fatigue failures have been investigated in the Piping and Fitting Dynamic Reliability Research Program (PRDRRP). This program was sponsored by EPRI and NRC and was performed by General Electric from 1985 to 1988. Forty-one piping components have been tested, which consisted of elbows, tees, reducers, nozzles and supports. In addition, two piping systems were tested for seismic loads and two other systems were tested for seismic loads and two other systems were tested for water hammer loads. In the test program seismic time history inputs, typical of those expected to occur at nuclear plants were scaled up to 50 times in amplitude to investigate the dynamic behavior and the failure modes of the piping components and piping systems. Most of the systems were pressurized at room temperature and were tested to failure. High strain rossettes were installed at high stress locations to measure the cyclic strains and ratcheting strains. In addition, scratch marks were made on the high stress locations. The elongation of the scratch marks were recorded to evaluate the ratcheting strains for each of the seismic test runs. This paper presents the ratcheting strain data. The measured ratcheting strains were compared to the ratcheting strains prediction using the approach by both the Miller Model and Edmunds-Bear Model. The fatigue failure data were compared with fatigue analyses

  5. Powder metallurgy bearings for advanced rocket engines

    Fleck, J. N.; Killman, B. J.; Munson, H.E.

    1985-01-01

    Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.

  6. On Controllable Elastohydrodynamic Fluid Film Bearings

    Haugaard, Martin Asger

    This thesis gives a theoretical description of the active tilting-pad journal bearing (ATPJB). It provides the qualified reader with the tools to model an ATPJB, while staying clear of pitfalls. The model is based on well known techniques and allows for local stability analyses, harmonic stationary...... are performed for a tilting-pad journal bearing (TPJB) and an ATPJB under static conditions, followed by a generalisation to dynamic conditions (transient as well as stationary harmonic). These analyses will be of interest to experimentalists, since they permit experiments performed on scaled down...... great care, since the addition of a control system may just as well harm rotor-bearing performance as improve it....

  7. Robust bearing estimation for 3-component stations

    CLAASSEN,JOHN P.

    2000-02-01

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the inherent information in the arrival at every step of the process to achieve near-optimal results. In particular the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, and finally to apply bias corrections when calibration information is available to yield a single final estimate. The algorithm was applied to a small but challenging set of events in a seismically active region. It demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted from these findings.

  8. Diffraction tomography of strain

    Lionheart, W R B; Withers, P. J.

    2015-01-01

    We consider whether it is possible to recover the three dimensional strain field tomographically from neutron and x-ray diffraction data for polycrystalline materials. We show that the distribution of strain transverse to a ray cannot be deduced from one diffraction pattern accumulated along that path, but that a certain moment of that data corresponds to the transverse ray transform of the strain tensor and so may be recovered by inverting that transform given sufficient data. We show that t...

  9. Big Bear Exploration Ltd. 1998 annual report

    During the first quarter of 1998 Big Bear completed a purchase of additional assets in the Rainbow Lake area of Alberta in which light oil purchase was financed with new equity and bank debt. The business plan was to immediately exploit these light oil assets, the result of which would be increased reserves, production and cash flow. Although drilling results in the first quarter on the Rainbow Lake properties was mixed, oil prices started to free fall and drilling costs were much higher than expected. As a result, the company completed a reduced program which resulted in less incremental loss and cash flow than it budgeted for. On April 29, 1998, Big Bear entered into agreement with Belco Oil and Gas Corp. and Moan Investments Ltd. for the issuance of convertible preferred shares at a gross value of $15,750,000, which shares were eventually converted at 70 cents per share to common equity. As a result of the continued plunge in oil prices, the lending value of the company's assets continued to fall, requiring it to take action in order to meet its financial commitments. Late in the third quarter Big Bear issued equity for proceeds of $11,032,000 which further reduced the company's debt. Although the company has been extremely active in identifying and pursuing acquisition opportunities, it became evident that Belco Oil and Gas Corp. and Big Bear did nor share common criteria for acquisitions, which resulted in the restructuring of their relationship in the fourth quarter. With the future of oil prices in question, Big Bear decided that it would change its focus to that of natural gas and would refocus ts efforts to acquire natural gas assets to fuel its growth. The purchase of Blue Range put Big Bear in a difficult position in terms of the latter's growth. In summary, what started as a difficult year ended in disappointment

  10. Strained Silicon Photonics

    Ralf B. Wehrspohn

    2012-05-01

    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  11. Strain-engineered MOSFETs

    Maiti, CK

    2012-01-01

    Currently strain engineering is the main technique used to enhance the performance of advanced silicon-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Written from an engineering application standpoint, Strain-Engineered MOSFETs introduces promising strain techniques to fabricate strain-engineered MOSFETs and to methods to assess the applications of these techniques. The book provides the background and physical insight needed to understand new and future developments in the modeling and design of n- and p-MOSFETs at nanoscale. This book focuses on recent developments in st

  12. Conflict Bear Translocation: Investigating Population Genetics and Fate of Bear Translocation in Dachigam National Park, Jammu and Kashmir, India

    Mukesh,; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth ‘conflict bears’ from different sit...

  13. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    Endo, Koji; Grubbs, Robert H.

    2016-01-01

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  14. A CAD approach to magnetic bearing design

    Jeyaseelan, M.; Anand, D. K.; Kirk, J. A.

    1988-01-01

    A design methodology has been developed at the Magnetic Bearing Research Laboratory for designing magnetic bearings using a CAD approach. This is used in the algorithm of an interactive design software package. The package is a design tool developed to enable the designer to simulate the entire process of design and analysis of the system. Its capabilities include interactive input/modification of geometry, finding any possible saturation at critical sections of the system, and the design and analysis of a control system that stabilizes and maintains magnetic suspension.

  15. Wear Analysis of Wind Turbine Gearbox Bearings

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  16. Grouted Pile and Its Bearing Capacity

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  17. Rotor/bearing system dynamic stiffness measurements

    Muszynska, A.

    1985-01-01

    Sweep perturbation testing as used in Modal Analysis when applied to a rotating machine has to take into consideration the machine dynamic state of equilibrium at its operational rotative speed. This stands in contrasts to a static equilibrium of nonrotating structures. The rotational energy has a significant influence on rotor dynamic characteristics. The best perturbing input for rotating machines is a forward or reverse rotating, circular force applied directly to the shaft. Determination of Dynamic Stiffness Characteristics of the rotor bearing system by nonsynchronous perturbation of a symmetric rotating shaft supported in one relatively rigid and one oil lubricated bearing.

  18. Bear Lake Basin : History, geology, biology, people

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    Bear Lake is a large, deep lake located on the border of Utah and Idaho in Rich County Utah and Bear Lake County Idaho. It was formed through seismic activity along a fault on the eastern side of the lake. Tectonic shifts of the plates along this fault resulted in a lake basin that is over 200 ft deep along the eastern shore with a gradual slope to the western shore. The lake water has high concentrations of calcium carbonate because of high levels of evaporation typical of this semi-arid ...

  19. ACS air bearing test-bed design

    Glitt, Sascha

    2010-01-01

    This thesis is about the construction and design of a new air bearing test-bed to verify the programmed ACS attitude control algorithm and to validate the ACS MATLAB/SimuLink¬ model of NPSAT1, the second small satellite currently under development at the Naval Postgraduate School Space Systems Academic Group. The software was already verified and validated using a comparable air bearing test-bed. But due to changes in hardware from commercial magnetic torque rods to custom, NPS-built, magneti...

  20. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    David Fraser

    2013-09-01

    Full Text Available The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing.

  1. Tests of reduced-scale seismic isolation bearings for the U.S. Advanced Liquid Metal Reactor (ALMR) program

    This paper summarizes a portion of a thorough series of tests on several different designs of reduced-scale high damping rubber isolators for the U.S. Advanced Liquid Metal Reactor (ALMR) program. A formal procurement specification has been developed by the program participants for purchasing bearings of several different scale factors and designs. The reduced-scale bearings in the specification have geometric scale factors of 1/4 and 1/8 so that dynamic tests can be performed at realistic rates, The 1/8-scale bearings also have a range of rubber layer thicknesses so that the effects of shape factor on mechanical properties may be determined. Tests of bearings from two suppliers using one of the 1/8-scale bearing designs are summarized here. The test program includes horizontal shear tests to moderate and high shear strains at a range of axial loads and frequencies, as well as vertical tests and failure tests to quantify the margin of safety in the actual design. Load-History effects including short-term stiffness reduction and long-term stiffness recovery are also under study. The primary focus of these tests is on characterizing the behavior of the compounds proposed by the bearing suppliers

  2. Tests of reduced-scale seismic isolation bearings for the U.S. Advanced Liquid Metal Reactor (ALMR) program

    Clark, P.W.; Aiken, I.D.; Kelly, J.M. [Univ. of California, Berkeley, CA (United States). Earthquake Engineering Research Center; Gluekler, E.L. [General Electric Co., San Jose, CA (United States); Tajirian, F.F. [Bechtel National Corp., San Francisco, CA (United States)

    1995-12-01

    This paper summarizes a portion of a thorough series of tests on several different designs of reduced-scale high damping rubber isolators for the U.S. Advanced Liquid Metal Reactor (ALMR) program. A formal procurement specification has been developed by the program participants for purchasing bearings of several different scale factors and designs. The reduced-scale bearings in the specification have geometric scale factors of 1/4 and 1/8 so that dynamic tests can be performed at realistic rates, The 1/8-scale bearings also have a range of rubber layer thicknesses so that the effects of shape factor on mechanical properties may be determined. Tests of bearings from two suppliers using one of the 1/8-scale bearing designs are summarized here. The test program includes horizontal shear tests to moderate and high shear strains at a range of axial loads and frequencies, as well as vertical tests and failure tests to quantify the margin of safety in the actual design. Load-History effects including short-term stiffness reduction and long-term stiffness recovery are also under study. The primary focus of these tests is on characterizing the behavior of the compounds proposed by the bearing suppliers.

  3. Multi-property characterization chamber for geophysical-hydrological investigations of hydrate bearing sediments.

    Seol, Yongkoo; Choi, Jeong-Hoon; Dai, Sheng

    2014-08-01

    With the increase in the interest of producing natural gas from methane hydrates as well as potential risks of massive hydrate dissociation in the context of global warming, studies have recently shifted from pure hydrate crystals to hydrates in sediments. Such a research focus shift requires a series of innovative laboratory devices that are capable of investigating various properties of hydrate-bearing sediments (HBS). This study introduces a newly developed high pressure testing chamber, i.e., multi-property characterization chamber (MPCC), that allows simultaneous investigation of a series of fundamental properties of HBS, including small-strain stiffness (i.e., P- and S-waves), shear strength, large-strain deformation, stress-volume responses, and permeability. The peripheral coolant circulation system of the MPCC permits stable and accurate temperature control, while the core holder body, made of aluminum, enables X-ray computer tomography scanning to be easily employed for structural and morphological characterization of specimens. Samples of hydrate-bearing sediments are held within a rubber sleeve inside the chamber. The thick sleeve is more durable and versatile than thin membranes while also being much softer than oedometer-type chambers that are incapable of enabling flow tests. Bias introduced by the rubber sleeve during large deformation tests are also calibrated both theoretically and experimentally. This system provides insight into full characterization of hydrate-bearing sediments in the laboratory, as well as pressure core technology in the field. PMID:25173288

  4. Multi-property characterization chamber for geophysical-hydrological investigations of hydrate bearing sediments

    With the increase in the interest of producing natural gas from methane hydrates as well as potential risks of massive hydrate dissociation in the context of global warming, studies have recently shifted from pure hydrate crystals to hydrates in sediments. Such a research focus shift requires a series of innovative laboratory devices that are capable of investigating various properties of hydrate-bearing sediments (HBS). This study introduces a newly developed high pressure testing chamber, i.e., multi-property characterization chamber (MPCC), that allows simultaneous investigation of a series of fundamental properties of HBS, including small-strain stiffness (i.e., P- and S-waves), shear strength, large-strain deformation, stress-volume responses, and permeability. The peripheral coolant circulation system of the MPCC permits stable and accurate temperature control, while the core holder body, made of aluminum, enables X-ray computer tomography scanning to be easily employed for structural and morphological characterization of specimens. Samples of hydrate-bearing sediments are held within a rubber sleeve inside the chamber. The thick sleeve is more durable and versatile than thin membranes while also being much softer than oedometer-type chambers that are incapable of enabling flow tests. Bias introduced by the rubber sleeve during large deformation tests are also calibrated both theoretically and experimentally. This system provides insight into full characterization of hydrate-bearing sediments in the laboratory, as well as pressure core technology in the field

  5. On the Design of Tilting-Pad Thrust Bearings

    Heinrichson, Niels

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...... geometries are given. Parallel-step bearings theoretically have smaller friction coefficients than tilting-pad bearings. A design of a tilting-pad bearing is suggested which combines the benefits of the two types of bearings in a tilting-pad bearing with inlet pockets. This design results in a substantial...

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

    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. Highly Strained Organophosphorus Compounds

    Slootweg, J.C.

    2005-01-01

    In our research on small, strained organophosphorus ring systems we became interested in the synthesis and applications of species that are even more strained than the parent phosphirane, by introducing an exocyclic double bond (methylenephosphirane), and by cyclopropyl spirofusion to the edge (e.g

  8. Extended Life Testing of Duplex Ball Bearings

    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.

  9. Angular-momentum-bearing modes in fission

    The angular-momentum-bearing degrees of freedom involved in the fission process are identified and their influence on experimental observables is discussed. The excitation of these modes is treated in the ''thermal'' limit, and the resulting distributions of observables are calculated. Experiments demonstrating the role of these modes are presented and discussed. 61 refs., 12 figs

  10. Bearings fault detection using inference tools

    Prieto, Miguel Delgado; Roura, Jordi Cusidó i; Martínez, Jose Luis Romeral

    2011-01-01

    The most used electric machine in the industry is the Induction Motor (IM), due to its simplicity and reduced cost. The analysis of the origin of IMs failures exhibits that the bearings are the major source of fault, and even a common cause of degradation in other kinds of motors as Permanent Magnet Synchronous Machines.

  11. The economics of roadside bear viewing

    Richardson, Leslie; Rosen, Tatjana; Gunther, Kerry; Schwartz, Chuck

    2014-01-01

    Viewing bears along roadside habitats is a popular recreational activity in certain national parks throughout the United States. However, safely managing visitors during traffic jams that result from this activity often requires the use of limited park resources. Using unique visitor survey data, this study quantifies economic values associated with roadside bear viewing in Yellowstone National Park, monetary values that could be used to determine whether this continued use of park resources is warranted on economic grounds. Based on visitor expenditure data and results of a contingent visitation question, it is estimated that summer Park visitation would decrease if bears were no longer allowed to stay along roadside habitats, resulting in a loss of 155 jobs in the local economy. Results from a nonmarket valuation survey question indicate that on average, visitors to Yellowstone National Park are willing to pay around $41 more in Park entrance fees to ensure that bears are allowed to remain along roads within the Park. Generalizing this value to the relevant population of visitors indicates that the economic benefits of allowing this wildlife viewing opportunity to continue could outweigh the costs of using additional resources to effectively manage these traffic jams.

  12. Thermo-hydrodynamic lubrication in hydrodynamic bearings

    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 thermo-hydrodynamic and the thermo-elasto-hydrodynamic lubrication. The algorithms are methodically detailed and each section is thoroughly illustrated.

  13. Weak and strong nonlinearities in magnetic bearings

    Půst, Ladislav

    2004-01-01

    Roč. 39, č. 7 (2004), s. 779-795. ISSN 0094-114X R&D Projects: GA ČR GA101/00/1471; GA AV ČR IBS2076301 Institutional research plan: CEZ:AV0Z2076919 Keywords : weak nonlinearitiy * strong nonlinearity * magnetics bearings Subject RIV: BI - Acoustics Impact factor: 0.605, year: 2004

  14. Experimental investigation of gas aerostatic bearings

    Steinbauer, P.; Šika, Z.; Kozánek, Jan; Šimek, J.

    2008-01-01

    Roč. 3, - (2008), s. 769-776. ISSN 1335-2393 R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * experimental identification * measurement Subject RIV: BI - Acoustics

  15. Surface layer characterisation of bearing rings

    S.J. Skrzypek

    2007-11-01

    Full Text Available austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in bearing rings and following measurements of residual stresses were carried out as well. The bearing elements were made of 100Cr6 steel and they were smoothed and grinded.Design/methodology/approach: Particular features of diffraction patterns like angle position; shape and intensity are used to characterize phase composition, residual micro and macro-stresses, crystallographic texture, lattice parameter, defects density and crystalline size.Findings: Machining by micro-deformation causes microstructural changes i.e. mechanically induced phase transformation of retained austenite and residual macrostresses. E.g. grinding cased tension and small compression whereas the mechanical smoothing of bearing rings caused high compresive residual stresses about -713 MPa.Research limitations/implications: For precise interpretation of differences between following results needs another investigations: i.e. measurement of retained austenite and residual stresses in rings after heat treatment before any mechanical treatment.Practical implications: The non-destructive character and large number of structural informations contained in diffraction pattern are the beneficial feature of diffraction methods. Therefore they have potential ability in application to technological operations and to diagnostic during fatigue.Originality/value: The non-destructive structure characterisation of surface layers for various kinds of bearing rings can be powerful method in surface characterization and in quality control. This results contribute in general relations between microstructure and properties.

  16. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.

  17. Load-Bearing Capacity of Roof Trusses

    Sørensen, John Dalsgaard; Damkilde, Lars; Munch-Andersen, J.

    2004-01-01

    structural systems such as roof trusses are established and statistical characteristics of the load bearing capacity are determined. The results show that there is a significant increase in the characteristic (nominal) value and a reduction in the coefficient of variation (COV) for typical loads such as...

  18. Grievous Temporal and Occipital Injury Caused by a Bear Attack

    Sampath Chandra Prasad; Nikhil Dinaker Thada; Pallavi Rao; Smitha Rani Thada; Kishore Chandra Prasad

    2013-01-01

    Bear attacks are reported from nearly every part of the world. The chance of a human encountering a bear increases as the remote bear territory diminishes. The sloth bear is one of the three species of bears found in India, which inhabits the forests of India and its neighboring countries. Here we describe a teenager who came to us with a critical injury involving the face, temporal and occipital bones inflicted by a sloth bear attack. He underwent a temporal exploration, facial nerve decompr...

  19. Computing Operating Characteristics Of Bearing/Shaft Systems

    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.

  20. Occurrence, characterization and insecticidal activity of Bacillus thuringiensis strains isolated from argan fields in Morocco.

    Aboussaid, H; Vidal-Quist, J C; Oufdou, K; El Messoussi, S; Castañera, P; González-Cabrera, J

    2011-01-01

    Soils collected from five locations in the argan forest (an endemic plant) in Morocco were used to form the first collection of Bacillus thuringiensis (Bt) strains from this area (58 strains). Here we found that the argan forest is a major source of Bt, as 90.62% of the samples contained Bt strains. These strains produced mainly spherical or irregular crystals that in some cases remained adhered to the spore after cell lysis. There was no strain producing bipyramidal crystals, suggesting the absence of strains bearing crv1 genes. This was confirmed by PCR analysis using eight primer pairs that can potentially detect 13 different groups of cry and cyt genes. Strains containing cry7/8 were the most abundant (25.53%), followed by strains harbouring cry9A (14.89%), cry11 (8.51%) and cry4 (4.25%). The mixtures of spores and crystals as well as culture supernatants were assayed for toxicity towards Ceratitis capitata (Medfly), showing up to 30% mortality. Our findings suggest that the argan region is a suitable target for future and wider screening programmes looking for strains bearing toxins or combinations of them to develop more efficient Bt-based formulates. PMID:21970180

  1. Involvement of apurinic sites in the synergistic action of alkylating and intercalating drugs in Escherichia coli.

    Malvy, C; Safraoui, H; Bloch, E; Bertrand, J R

    1988-03-01

    The toxicity of the intercalating compounds 9-aminoellipticine (9AE) and isopropyl-oxazolopyridocarbazole (Ipr-OPC) were studied. The inhibitory effect of non-toxic doses of 9AE, which incises DNA at apurinic (AP) sites, or Ipr-OPC, which does not cleave DNA at AP sites, with non-toxic doses of the alkylating agent dimethylsulphate (DMS) on the growth of Escherichia coli strain AB1157, is additive. The same result has been observed with an exonuclease III mutant which has only 10% of the AP endonuclease activity. However, 9AE or Ipr-OPC display a synergistic toxic effect with a DMS concentration which allows 20% of E. coli AB1157 survival. This synergy is increased for 9AE in the AP endonuclease mutant when compared to the wild-type strain. Under identical conditions 9AE and Ipr-OPC have no synergistic effect on a mutant deficient in the enzymes which generate AP sites. Therefore AP sites are involved in the synergistic toxicity of DMS and the studied intercalating agents. However, the precise role of the interaction of intercalating agents with AP sites, either without cleavage (type 1 compounds) or with cleavage (type 2 compounds), in the observed effect remains an open question. PMID:3284541

  2. Characterization of the High-Speed-Stage Bearing Skidding of Wind Turbine Gearboxes Induced by Dynamic Electricity Grid Events: Preprint

    Helsen, Jan; Guillaume, Patrick; Guo, Yi; Keller, Jonathan

    2016-05-18

    Bearing behavior is an important factor for wind turbine drivetrain reliability. Extreme loads and dynamic excitations pose challenges to the bearing design and therefore its performance. Excessive skidding of the bearing rollers should be avoided because it can cause scuffing failures. Excitations coming from wind and the electricity grid can subject the drivetrain to fluctuating torque and nontorque loads. Wind-induced excitations have been investigated predominantly in literature. However, modern wind turbines are subjected more and more to grid-induced loads because of stricter electricity grid regulations. For example, during fault-ride-through events, turbines are required to stay connected for a longer period of time during the grid failure. This work investigates the influence of electrically induced excitations on the skidding behaviour of the tapered roller bearings on the high-speed stage of a wind turbine gearbox. This skidding behaviour during dynamic events is described as a potential bearing failure initiator by many researchers; however, only limited full-scale dynamic testing is documented. Therefore, a dedicated gridloss-type event is defined in the paper and conducted in a dynamometer test on a full-scale wind turbine nacelle. During the event, a complete electricity grid failure is simulated while the turbine is at rated speed and predefined torque levels. Particular focus is on the characterization of the high-speed shaft tapered roller bearing slip behavior. Strain-gauge bridges in grooves along the circumference of the outer ring are used to characterize the bearing load zone in detail. It is shown that during the torque reversals of the transient event, roller slip can be induced. This indicates the potential of the applied load case to go beyond the preload of the tapered roller bearing. Furthermore, the relation between the applied torque and skidding level is studied.

  3. Rotor Bearing System Analysis Using the Transfer Matrix Method with Thickness Assumption of Disk and Bearing

    Ghasemalizadeh, Omid; Sadeghi, Hossein; Ahmadian, Mohammad Taghi

    2013-01-01

    One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary conditions to the discretized system. In this paper the dynamics of a rotor-bearing system is analyzed, considering the gyroscopic effect. The thickness of the disk and bearings is also taken into account. Continuous model is used for shaft. Results Show that, the stiffness of the shaft and the natural frequencies of the system increase, while the amplitude of vibration decreases as a consequence of increasing the thickness of the bearing.

  4. Kenai Peninsula Brown Bear Studies : Report of the Interagency Brown Bear Study Team, 1986

    US Fish and Wildlife Service, Department of the Interior — This report summarizes work conducted during the 1986 field season on brown bear Ursus arctos from the Kenai Peninsula, Alaska. Ground surveys were conducted to...

  5. Compression and shear properties of elastomeric bearing using finite element analysis

    2Faculty of Science and Technology, Chiang Mai Rajabhat University, Muang, Chiang Mai, 50300 Thailand.

    2006-09-01

    Full Text Available Standard size samples of four natural rubber compounds, varying the amount of carbon black from 10 to 70 phr, were characterised under uniaxial compression and simple shear tests in order to obtain the strain energy function constants. These constants were then used as hyperelastic material constants for the Windows-based finite element package (COSMOS/M version 1.75. The investigated bearings, made with those NR compounds, had the approximate area and thickness of 50x106 mm2 and 50 mm respectively. Each compound of bearing consisted of four different values of shape factor ranging from about 0.33 to 1.70, according to the number of reinforcing plates in the bearing. Three deformation modes of compression, shear and compression-shear were predicted. Good agreement was found between twelve compression model predictions and the corresponding experimental values of bearings, containing 10, 20 and 40 phr of carbon black and each of which consisted of four different layers of reinforcing metal plates (0, 1, 2 and 3 layers. On the other hand, deviation from the predicted valve was clearly seen in the 70 phr black bearing case. The percentage difference increased with respect to the increasing number of reinforcing plates or the rising shape factor. Therefore, the improved FEA model was supplemented with an imaginary elastic glue layer between the rubber block and metal plate as glue failure compensation. The optimum value of the elastic layers modulus is 8 MPa while the thickness of the layer depends on the total thickness or total volume of rubber block. This model can predict the 70 phr carbon black bearings, having shape factor ranging from 0.5 to 2.35 for 11 cases. The FEA prediction of shear behaviour agrees well with the experimental data for all four bearing compounds and there is no effect of shape factor on shear stress. Moreover, shear stress does not depend on the compressive force applied to like bearing before shear and the FEA results

  6. Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

    Amin Keshavarz

    2016-04-01

    Full Text Available In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided for analysis. Given the footing and rock parameters, the code can calculate the stress characteristics network and obtain the stress distribution under the footing. The seismic effects have been applied as the horizontal and vertical pseudo-static coefficients. The results of this paper are very close to those of the other studies. The seismic bearing capacity of weightless rock masses can be obtained using the proposed equations and graphs without calculating the whole stress characteristics network.

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

    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.

  8. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    David Fraser; Sara Dubois

    2013-01-01

    Simple Summary The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia. Residents of this small community were surveyed by phone twice over the following year, before and after government actions. This study aimed to understand local attitudes on how these bears should be managed and whether they differed from existing bea...

  9. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    Zhengjun Tang; Daibiao Zhou; Chenwei Peng; Wenping Wu

    2015-01-01

    The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with prof...

  10. The thermodynamic properties of a new type catcher bearing used in active magnetic bearings system

    Normally a rotor levitated by active magnetic bearings (AMBs) system would rotate without contacting with any stator component, but the possibility still remains that the supporting force might lose temporarily or permanently, thus requiring the Catcher bearings (CBs) to provide backup protection in case of the failure of AMBs. A new type CB with two separate rolling element bearing series could have the speed distribution between the inner race and intermediate race according to certain ratio, in which the speed of each roller element bearing decreases with the limit speed of the whole CB increasing, offering high capability to sustain its initial rotation speed. Based on the theory of heat transfer, tribology, and rotor dynamics, this paper analyzes the thermal structure of double-decker catcher bearing (DDCB) and single-decker catcher bearing (SDCB), respectively. Through this structure, the thermal resistances and equations of heat transfer can be obtained. Then we calculate the friction heat and temperature distribution in the various CBs upon rotor's dropping on SDCB or DDCB, followed by the discussion on the CBs temperature rise's effects on lubrication conditions and rotor dynamics parameters. Finally various experiments are carried out to measure the temperature rise of different CBs. The results obtained validate the theoretical analysis and also provide main methods to reduce heat generation. Using DDCB is proved to be effective to reduce the temperature rise. - Highlights: • The DDCB is a more suitable catcher bearing for AMBs. • Compared to SDCB, using DDCB, the temperature rise can decrease in the same states. • A lower viscosity of lubricant may induce a lower temperature rise. • The inner raceway temperature of the first layer bearing is the highest. • Reducing the unbalance mass of the rotor is a method to decrease the temperature rise

  11. Biomechanical analysis of fixed bearing and mobile bearing total knee prostheses

    Urwin, Samuel

    2014-01-01

    In total knee replacement (TKR) surgery, mobile bearing (MB) total knee prostheses were designed to more closely mimic the function of the normal knee than traditional fixed bearing (FB) designs by allowing axial mobility between the polyethylene insert and tibial tray. Despite the hypothetical benefits of the MB design, few studies have objectively analysed knee biomechanics during activities of daily living (ADLs) in the laboratory compared to FB designs. This thesis aimed to substantiate t...

  12. Population Parameters and Harvest Characteristics of Black Bears in Georgia

    US Fish and Wildlife Service, Department of the Interior — This report summarizes findings of black bear distribution and population trends throughout Georgia and evaluates black bear harvest trends from 1992 to 2002....

  13. Kodiak brown bear population on Kodiak Island, Alaska

    US Fish and Wildlife Service, Department of the Interior — Methods and estimates of the Brown bear population on Kodiak Island. The total number of Kodiak Brown Bears on Kodiak Island has been estimated to be 1669. Three...

  14. Investigation of tribological and mechanical properties of metal bearings

    Bekir Sadik Ünlü

    2009-08-01

    Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.

  15. Self-Bearing Motor-Generator for Flywheels Project

    National Aeronautics and Space Administration — Self-bearing or ?bearingless? motors perform both motor and bearing support functions but such devices have not yet achieved speeds above 15,000 rpm. The innovation...

  16. Polar bear den survey, Arctic National Wildlife Range

    US Fish and Wildlife Service, Department of the Interior — In conjunction with the Polar Bear Research Project being supervised by Mr. Jack Lentfer of the Bureau of Sport Fisheries and Wildlife two Polar Bear den surveys...

  17. Interchangeable Bearings for Profile and Weight Trade Studies Project

    National Aeronautics and Space Administration — Air-Lock, Incorporated is proposing to design fully sealed shoulder and arm bearings with interchangeable bearing housings. The interchangeable housings shall be...

  18. Blade Bearing Friction Estimation of Operating Wind Turbines

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    Blade root bearing on a wind turbine (WTG) enables pitching of blades for power control and rotor braking and is a WTG critical component. As the size of modern WTGs is constantly increasing, this leads to relatively less rigid bearings, more sensitive to deformations, thus WTG operational...... reliability can be increased by continuous monitoring of blade bearing. High blade bearing friction is undesirable, as it may be associated with excessive heating of the surfaces, damage and/or inefficient operation. Thus, continuous observation of bearing friction level is crucial for blade bearing health...... monitoring systems. A novel algorithm for online monitoring of bearing friction level is developed combining physical knowledge about pitch system dynamics with state estimator, i.e. observer theory and signal processing assuming realistic sensor availability. Results show estimation of bearing friction...

  19. A plan for the management of the Kodiak brown bear

    US Fish and Wildlife Service, Department of the Interior — Management districts will be used as a tool to manage the population of bear on Kodiak Island. Theoretically, 204 bear may be taken off the refuge annually without...

  20. Shaft centre orbit for dynamically loaded radial bearings

    Klit, Peder; Vølund, Anders

    2002-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 Booker1 and described further in 1972 Booker2. Several authors have refined...... this method over the years. In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold´s equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In...... the mid seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in...

  1. The possibility of evaluating turbo-set bearing misalignment defects on the basis of bearing trajectory features

    Rybczyński, Józef

    2011-02-01

    This paper presents the results of computer simulation of bearing misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-bearing rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil bearings. The results are presented in the form of a set of journal and bush trajectories of all turbo-set bearings. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine bearings in horizontal and vertical directions by the maximum acceptable range calculated with regard to bearing vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible bearing dislocations. We show the relations between the attributes of the particular bearing trajectories and the bearing displacements in relation to their base design position. The shape and dimensions of bearing trajectories are interpreted based on the theory of hydrodynamic lubrication of oil bearings. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which bearings are loaded. Therefore, trajectories can be a source of information about the position and direction of bearing misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.

  2. Rotor stability estimation with competing tilting pad bearing models

    Cloud, C. Hunter; Maslen, Eric H.; Barrett, Lloyd E.

    2012-05-01

    When predicting the stability of rotors supported by tilting pad journal bearings, it is currently debated whether or not the bearings should be represented with frequency dependent dynamics. Using an experimental apparatus, measurements of pad temperatures, unbalance response and stability are compared with modeling predictions for two tilting pad bearing designs. Predictions based on frequency dependent tilting pad bearing dynamics exhibited significantly better correlation with the stability measurements than those assuming frequency independent dynamics.

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

    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...

  4. Stiffness calculation and application of spline-ball bearing

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

    2006-12-01

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

  5. Passive axial stabilization of a magnetic radial bearing by superconductors

    Marinescu, M.; Marinescu, N. (Ing.-Buro f. Magnettechnik, Mailander Str.19, D-6000 Frankfurt/M. 70 (DE)); Tenbrink, J.; Krauth, H. (Vacuumschmelze GmbH, Gruner Weg 37, D-6450 Hanau (DE))

    1989-09-01

    Contactless bearings for high-speed operation can be constructed using passive magnet systems, which inherently need a second, active bearing for their stabilization. Completely passive bearings only can be obtained using diamagnetic materials. This study deals with the axial stabilization of magnetic radial bearings using a permanent magnet/superconductor system. Using finite element calculation procedures it is shown that axial forces of up 3000 N and stiffnesses of up to 400 N/mm may be achieved.

  6. Sprains and Strains

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  7. The strained state cosmology

    Tartaglia, Angelo

    2015-01-01

    Starting from some relevant facts concerning the behaviour of the universe over large scale and time span, the analogy between the geometric approach of General Relativ- ity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time repro- duces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theor...

  8. Testing a coupled hydro-thermo-chemo-geomechanical model for gas hydrate bearing sediments using triaxial compression lab experiments

    Gupta, Shubhangi; Haeckel, Matthias; Helmig, Rainer; Wohlmuth, Barbara

    2015-01-01

    The presence of gas hydrates influences the stress-strain behavior and increases the load-bearing capacity of sub-marine sediments. This stability is reduced or completely lost when gas hydrates become unstable. Since natural gas hydrate reservoirs are considered as potential resources for gas production on industrial scales, there is a strong need for numerical production simulators with geomechanical capabilities. To reliably predict the mechanical behavior of gas hydrate-bearing sediments during gas production, numerical tools must be sufficiently calibrated against data from controlled experiments or field tests, and the models must consider thermo-hydro-chemo-mechanical process coupling in a suitable manner. In this study, we perform a controlled triaxial volumetric strain test on a sediment sample in which methane hydrate is first formed under controlled isotropic effective stress and then dissociated via depressurization under controlled total stress. Sample deformations were kept small, and under thes...

  9. Static Load Distribution in Ball Bearings

    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.

  10. An Evershed type superconducting flywheel bearing

    Cansiz, A.; Campbell, A.M.; Coombs, T.A

    2003-07-15

    The objective of this work is to develop a bearing using high temperature superconductors (HTSs) for use in an energy storage flywheel. The experimental apparatus includes a cylindrical rotor levitated with the Evershed design in which the majority of the levitation force is provided by a permanent magnet arrangement and the stabilization of the system is achieved by HTS elements. The design characteristics and dynamics of the bearing associated with the rotor part are presented. The instrumentation measures the out of balance force and magnetomechanical stiffness associated with the rotor. A study of the rotational losses was performed using free spin down experiments associated with magnetic field variation measurements. The results are consistent with the loss being caused by hysteresis in the superconductor due to magnet inhomogeneity.

  11. An Evershed type superconducting flywheel bearing

    The objective of this work is to develop a bearing using high temperature superconductors (HTSs) for use in an energy storage flywheel. The experimental apparatus includes a cylindrical rotor levitated with the Evershed design in which the majority of the levitation force is provided by a permanent magnet arrangement and the stabilization of the system is achieved by HTS elements. The design characteristics and dynamics of the bearing associated with the rotor part are presented. The instrumentation measures the out of balance force and magnetomechanical stiffness associated with the rotor. A study of the rotational losses was performed using free spin down experiments associated with magnetic field variation measurements. The results are consistent with the loss being caused by hysteresis in the superconductor due to magnet inhomogeneity

  12. Radioactivity and the French uranium bearing minerals

    This special issue of Regne Mineral journal is entirely devoted to the French uranium mining industry. It comprises 4 parts dealing with: the uranium mining industry in France (history, uranium rush, deposits, geologic setting, prosperity and recession, situation in 1998, ore processing); radioactivity and the uranium and its descendants (discovery, first French uranium bearing ores, discovery of radioactivity, radium and other uranium descendants, radium mines, uranium mines, atoms, elements and isotopes, uranium genesis, uranium decay, isotopes in an uranium ore, spontaneous fission, selective migration of radionuclides, radon in mines and houses, radioactivity units, radioprotection standards, new standards and controversies, natural and artificial radioactivity, hazards linked with the handling and collecting of uranium ores, conformability with radioprotection standards, radioactivity of natural uranium minerals); the French uranium bearing minerals (composition, crystal structure, reference, etymology, fluorescence). (J.S.)

  13. Mechatronics Applied to Fluid Film Bearings: Towards More Efficient Machinery

    Cerda Varela, Alejandro Javier

    Film Bearings: Towards more Efficient Machinery" was aimed at improving the state of the art regarding the usage of fluid film bearings as "smart" machine elements. Specifically, this project dealt with a tilting pad journal bearing design that features a controllable lubrication system, capable...

  14. 14 CFR 73.5 - Bearings; radials; miles.

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Bearings; radials; miles. 73.5 Section 73.5 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRSPACE SPECIAL USE AIRSPACE General § 73.5 Bearings; radials; miles. (a) All bearings and radials in this...

  15. PROVIDING SERVICEABILITY OF STRUCTURAL BEARING TYPES FOR ROADWAY BRIDGES

    R. I. Polyuga

    2010-03-01

    Full Text Available In the article the description of structural bearing types for roadway bridges and their classification is given. Special attention is paid to effective bearings with elastomeric materials – rubber, pot, spherical ones. Characteristic defects of structural bearings and demands of serviceability are noticed.

  16. 14 CFR 71.7 - Bearings, radials, and mileages.

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Bearings, radials, and mileages. 71.7 Section 71.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true...

  17. 24 CFR 3285.202 - Soil classifications and bearing capacity.

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Soil classifications and bearing... Soil classifications and bearing capacity. The soil classification and bearing capacity of the soil must be determined before the foundation is constructed and anchored. The soil classification...

  18. 49 CFR 230.103 - Tender roller bearing journal boxes.

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender roller bearing journal boxes. 230.103... Locomotives and Tenders Running Gear § 230.103 Tender roller bearing journal boxes. Tender roller bearing journal boxes shall be maintained in a safe and suitable condition....

  19. Temperature Distribution and Scuffing of Tapered Roller Bearing

    WANG Ailin; WANG Jiugen

    2014-01-01

    In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

  20. 77 FR 73967 - Drawbridge Operation Regulation; Bear Creek, Dundalk, MD

    2012-12-12

    ... Regulation; Bear Creek, Dundalk, MD'' in the Federal Register (77 FR 5201). The rulemaking concerned would... SECURITY Coast Guard 33 CFR Part 117 RIN 1625-AA09 Drawbridge Operation Regulation; Bear Creek, Dundalk, MD... highway bridge at Wise Avenue across Bear Creek, mile 3.4, between Dundalk and Sparrows Point, MD....

  1. Mechanical design problems associated with turbopump fluid film bearings

    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. Analyzing the use of pins in safety bearings

    da Fonseca, Cesar A. L. L.; Weber, Hans I.; Fleischer, Philip F.;

    2015-01-01

    A new concept for safety bearings is analyzed: useful in emergency situations, it shall protect the bearing from destruction by the use of pins which impact with a disc, both capable of good energy dissipation. Results of work in progress are presented by validating partial stages of the...... the bearing....

  3. An Ultrasonic Strain Gauge

    Kersemans, Mathias; Allaer, Klaas; Degrieck, Joris; Van Den Abeele, Koen; Pyl, Lincy; Zastavnik, Filip; Sol, Hugo; Van Paegem, Wim

    2014-01-01

    A method is introduced for the measurements of strain exploiting the interaction between ultrasound waves and characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incide...

  4. Low cycle fatigue behavior of a quenched and tempered niobium bearing HSLA steel

    Kwun, S.I. (Korea Univ., Seoul); Fournelle, R.A.

    1980-08-01

    The low cycle fatigue behavior of a quenched and tempered niobium (columbium) bearing high strength low alloy steel heat treated to give tempered martensitic microstructures presumably with and without fine niobium carbides was studied by transmission electron microscopy, stress relaxation, X-ray diffraction line broadening and strain-controlled fatigue testing. The steel without the niobium carbides cyclically softened rapidly at all strain amplitudes studied. This softening was attributed to the rearrangement of the dislocation substructure into a cell structure and to the accompanying decrease in internal stress. The steel presumably containing the fine niobium carbides cyclically softened to a lesser extent. This correlated with the observation that dislocations in this steel did not rearrange themselves into a cell structure and, hence, there was less change in the internal stress during cycling. The steel without the niobium carbides exhibited somewhat better strain-life behavior at large strain amplitudes. This was attributed to the cell structure being able to accomodate a greater amount of plastic strain in that steel.

  5. Motion of rotor supported on aerodynamic bearings

    Půst, Ladislav; Šimek, J.; Kozánek, Jan

    Praha : Institute of Thermomechanics AS CR, v. v. i., 2007 - (Zolotarev, I.), s. 235-236 ISBN 978-80-87012-06-2. [Engineering Mechanics 2007: national conference with international participation. Svratka (CZ), 14.05.2007-17.05.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : rotor dynamics * aerodynamic bearing * tilting pad s Subject RIV: BI - Acoustics

  6. Mutual interaction of two aerodynamic bearings

    Půst, Ladislav; Kozánek, Jan

    Lodz : Department of Automatics and Biomechanics Technical University of Lodz, 2007, s. 387-394. ISBN 978-83-924382-9-8. [Conference on Dynamical Systems - Theory and Applications /9./. Lodz (PL), 17.12.2007-20.12.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerodynamic bearing * evolutive systems * numerical solution Subject RIV: BI - Acoustics

  7. Sensorless Control of Axial Magnetic Bearings

    Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.

  8. Existence of equilibria in articulated bearings

    Buscaglia, G.; Ciuperca, I.; Hafidi, I.; Jai, M.

    2007-04-01

    The existence of equilibrium solutions for a lubricated system consisting of an articulated body sliding over a flat plate is considered. Though this configuration is very common (it corresponds to the popular tilting-pad thrust bearings), the existence problem has only been addressed in extremely simplified cases, such as planar sliders of infinite width. Our results show the existence of at least one equilibrium for a quite general class of (nonplanar) slider shapes. We also extend previous results concerning planar sliders.

  9. Determinattion of aerostatic journal bearing dynamic properties

    Kozánek, Jan; Šimek, J.; Steinbauer, P.; Neusser, Z.

    Praha: Ústav termomechaniky AV ČR, v. v. i., 2008 - (Pešek, L.), s. 161-168 ISBN 978-80-87012-10-9. [Dynamika strojů 2008. Praha (CZ), 05.02.2008-06.02.2008] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * stiffness and damping coefficients * identification Subject RIV: BI - Acoustics

  10. Low-Wear Ball-Bearing Separator

    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. Friction and wear of HPSN bearing materials

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

  12. Concurrent Initialization for Bearing-Only SLAM

    Antoni Grau

    2010-03-01

    Full Text Available Simultaneous Localization and Mapping (SLAM is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes.

  13. Concurrent initialization for Bearing-Only SLAM.

    Munguía, Rodrigo; Grau, Antoni

    2010-01-01

    Simultaneous Localization and Mapping (SLAM) is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range) cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras) in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes. PMID:22294884

  14. How Many Ore-Bearing Asteroids?

    Elvis, Martin

    2013-01-01

    A simple formalism is presented to assess how many asteroids contain ore, i.e. commercially profitable material, and not merely a high concentration of a resource. I apply this formalism to two resource cases: platinum group metals (PGMs) and water. Assuming for now that only Ni-Fe asteroids are of interest for PGMs, then 1% of NEOs are rich in PGMs. The dearth of ultra-low delta-v (= US$1 B and the population of near-Earth objects (NEOs) larger than 100 m diameter is ~20,000 (Mainzer et al. 2011) the total population of PGM ore-bearing NEOs is roughly 10. I stress that this is a conservative and highly uncertain value. For example, an order of magnitude increase in PGM ore-bearing NEOs occurs if delta-v can as large as 5.7 km s-1. Water ore for utilization in space is likely to be found in ~1/1100 NEOs. NEOs as small as 18 m diameter can be water-ore-bodies because of the high richness of water (~20%) expected in ~25% of carbonaceous asteroids, bringing the number of water-ore-bearing NEOs to ~9000 out of th...

  15. Hydrolyzable polyureas bearing hindered urea bonds.

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications. PMID:25406025

  16. AN INVESTIGATION OF MAGNETIC BEARING SYSTEMS

    Gürcan SAMTAŞ

    2007-02-01

    Full Text Available The magnetic bearing consists of levitating a shaft so that it is free to rotate about its axis. The magnetic bearing has the advantages of being very quiet work and very cleanliness because there is no mechanical friction or lubricants. The shaft has two permanent magnets attached to it. These two magnets determine a straight line rotation axis of the rotor shaft. The magnets are radially levitated and centered within a cavity by a passive permanent magnetic field in the adding stator housing assembly. The levitation and centering of the shaft axially is stabilized by a closed loop electronic servo circuit that regulates an electromagnetic field in the stator housing that pushes and pulls on the shaft magnets. The rotor weight can be between one gram and forty five thousand, four hundred grams. In 1985, the first magnetic bearing was developed that it had used to applications of gas turbines and other compressors. In these days, they can be used by many applications which are Medical, Transportation, Machine and Tools Industry, Aerospace, Vacuum and Clean room Environments... etc.

  17. Conservation of brown bear in the Alps: space use and settlement behavior of reintroduced bears

    Preatoni, Damiano; Mustoni, Andrea; Martinoli, Adriano; Carlini, Eugenio; Chiarenzi, Barbara; Chiozzini, Simonetta; Van Dongen, Stefan; Wauters, Luc A.; Tosi, Guido

    2005-11-01

    Large carnivores typically need large home ranges containing habitats patches of different quality. Consequently, their conservation requires habitat protection and management at the landscape scale. In some cases, reintroduction might be used to support remnant or restore extinct populations. This is the case for the brown bear ( Ursus arctos) in the Italian Alps. We monitored spacing behavior and settlement of reintroduced brown bears in Adamello-Brenta Natural Park, North-Italy, using radio-tracking. Habitat use, dispersion and survival were studied to evaluate the success of reintroduction and possible conflicts with man. All three males and five of seven females settled in the study area. Most bears roamed widely the first months after release, exploring the new habitat. Patterns of home range overlap between seasons and years revealed that home range use stabilized the year after first hibernation. Home ranges were larger in the mating season (May-July) than in spring or autumn. Home ranges varied between 34 and 1813 km 2 the year after release, but core-areas, where feeding activity was concentrated, were much smaller. Some bears had exclusive core-areas in summer and autumn, but most showed considerable core-area overlap with animals of the same and/or the opposite sex. Bears selected deciduous forests, mixed and conifer forests were used according to availability, and areas with anthropogenic disturbance were avoided. Most bears settled and some reproduced successfully at the release site, causing high initial population growth, suggesting that reintroduction can help to re-establish a brown bear population in the Italian Alps.

  18. Draft Genome Sequence of Xylella fastidiosa subsp. fastidiosa Strain Stag’s Leap

    Wu, F.; Zheng, Z.; Deng, X.; Burbank, L. P.; Stenger, D. C.

    2016-01-01

    Xylella fastidiosa subsp. fastidiosa causes Pierce’s disease of grapevine. Presented here is the draft genome sequence of the Stag’s Leap strain, previously used in pathogenicity/virulence assays to evaluate grapevine germplasm bearing Pierce’s disease resistance and a phenotypic assessment of knockout mutants to determine gene function. PMID:27103713

  19. Draft Genome Sequence of Xylella fastidiosa subsp. fastidiosa Strain Stag's Leap.

    Chen, J; Wu, F; Zheng, Z; Deng, X; Burbank, L P; Stenger, D C

    2016-01-01

    ITALIC! Xylella fastidiosasubsp. ITALIC! fastidiosacauses Pierce's disease of grapevine. Presented here is the draft genome sequence of the Stag's Leap strain, previously used in pathogenicity/virulence assays to evaluate grapevine germplasm bearing Pierce's disease resistance and a phenotypic assessment of knockout mutants to determine gene function. PMID:27103713

  20. Conflict bear translocation: investigating population genetics and fate of bear translocation in Dachigam National Park, Jammu and Kashmir, India.

    Mukesh; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth 'conflict bears' from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears) returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape. PMID:26267280

  1. Conflict bear translocation: investigating population genetics and fate of bear translocation in Dachigam National Park, Jammu and Kashmir, India.

    Mukesh

    Full Text Available The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth 'conflict bears' from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape.

  2. The daily habitual in-vivo strain history of a non-weight-bearing bone

    W.C. de Jong; J.H. Koolstra; J.A.M. Korfage; L.J. van Ruijven; G.E.J. Langenbach

    2010-01-01

    Daily mechanical loading strongly influences the architecture and composition of bone tissue. Throughout the day, the amplitudes, rates, frequencies, and the dispersion over time of these loads vary. Nevertheless, most experimental and descriptive studies on the aforementioned relationship consider

  3. MEMS Graphene Strain Sensor

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  4. Development and Evaluation of Titanium Space Suit Bearings

    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.

  5. Pile Model Tests Using Strain Gauge Technology

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

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

    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.

  7. Late Quaternary cave bears and brown bears in Europe: implications for distribution, chronology, and extinction based on a multidisciplinary approach

    Pacher, Martina

    2010-05-01

    Cave bear remains are one of the most numerous fossils found in European caves. Despite their frequency of occurrence, many aspects of cave bear palaeontology still remain poorly understood. New methodological approaches and ongoing studies led to controversial results and discussion about its taxonomy, palaeoecology, and final extinction. Are we dealing with one single or several species of cave bears? Was cave bear exclusively vegetarian or after all more omnivorous? Did he go extinct before or after the Late Glacial Maximum? Was cave bear restricted to Europe or did he also occur in Asia? Late Pleistocene brown bears, on the other hand, are often rare and little is known about the possible co-occurrence of cave and brown bears during the Late Pleistocene. Based on direct radiocarbon dates the distribution pattern of both, cave and brown bears is reconstructed during the Late Pleistocene in Europe. In addition, the reasons for the achieved pattern will be tested leading to the main question - why did cave bear become extinct while brown bears survived until today? To answer this question palaeobiological data of Late Pleistocene cave and brown bears will be tested against results from isotope analyses, while aDNA data may contribute to the question of distinct local population or even species of bears. The current state of evidence will be presented and on the basis of resulting pattern implications for further multi-disciplinary studies will be discussed.

  8. Bearing life in contaminated oil and oil passing into bearing for tapered roller bearing; Ensui koro jikuuke ni okeru ibutsu yuchu deno jumyo to kantsu yuryo

    Asai, Y.; Oshima, H.; Sakamoto, K. [Koyo Seiko Co. Ltd., Osaka (Japan)

    1997-10-01

    In this paper a relationship between depth of dents, area of dents gathered and bearing life has been investigated for tapered roller bearings used in differential gear case. It is effective for the longer bearing life to reduce hard particles of Fe especially among several contaminations existing in the gear case. It is also effective to make oil level lower in the case from the view point for reduction of number of dents. 8 refs., 8 figs., 4 tabs.

  9. Experimental verification of an eddy-current bearing

    Nikolajsen, Jorgen L.

    1989-01-01

    A new type of electromagnetic bearing was built and tested. It consists of fixed AC-electromagnets in a star formation surrounding a conducting rotor. The bearing works by repulsion due to eddy-currents induced in the rotor. A single bearing is able to fully support a short rotor. The rotor support is inherently stable in all five degrees of freedom. No feedback control is needed. The bearing is also able to accelerate the rotor up to speed and decelerate the rotor back to standstill. The bearing design and the experimentation to verify its capabilities are described.

  10. Stability of multi orifice active tilting-pad journal bearings

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that the...... nature and magnitude of this influence depends on the rotor mass, preload factor and rotational speed. Furthermore, it is shown that assuming the bearing pads to be rigid can produce a substantial error. A rigid pad model will overpredict the stable range of the bearing, thus it may lead to failure if...

  11. On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

    Morosi, Stefano; Santos, Ilmar

    2011-01-01

    modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... and drawbacks of this special kind of hybrid fluid film bearing....

  12. Relationship of rolling bearing stiffness with diameter of roller

    郭茂林; 王刚; 张瑞

    2002-01-01

    The theoretical formula of roller bearing stiffness is induced and compared with its empirical formula.In the experience formula the stiffness of roller bearing has nothing to do with the roller diameter. The relation-ship of roller bearing stiffness with roller diameter was studied using Hz contacting theory. It is concluded thatconclusion in experience formula is only approximate result of data processing under special conditions, and therelation between stiffness of roller bearing and roller diameter must be taken into consideration while designingor selecting roller bearings.

  13. Sudden venting test of an emergency bearing for the magnet bearing type compound molecular pump

    The vacuum evacuation system for nuclear fusion reactors bears the role of exhausting hydrogen isotopes in large quantity together with helium continuously for long hours, and as the high vacuum pumps for this purpose, the mechanical pumps which can do continuous evacuation and decrease the quantity of staying radioactive tritium, such as turbo molecular pumps and compound molecular pumps, are promising. Because of the compatibility with tritium, oil lubrication is not desirable, accordingly, the pumps with ceramic rotating vanes and magnetic bearings are demanded. As a part of the development of a magnetic bearing type mechanical pump which can be used for nuclear fusion reactors, the compound molecular pump, in which emergency bearings were incorporated, was made for trial, and the test of sudden air intrusion was carried out, as the results, various knowledges were obtained. The constitution of the testing setup, and the test results are reported. When air was injected at the pressure rise of 3.3x104 Pa/s from exhaust port side, after about 2.5 s, the maximum lift of 4.2x103 N arose. When air was injected at the pressure rise of 2.7x105 Pa/s from the suction part side, after about 0.4s, the maximum lift of 6.9x103 N arose. In the air injection alternately from the suction port and exhaust port sides, the emergency bearings functioned normally in 10 times of the test. (K.I.)

  14. Rolling Bearing Steels - A Technical and Historical Perspective

    Zaretsky, Erwin V.

    2012-01-01

    Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburizing grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with advanced lubrication technology, the potential improvements in bearing life can be as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability. The single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburized and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

  15. Analysis of thermoelastohydrodynamic performance of journal misaligned engine main bearings

    Bi, Fengrong; Shao, Kang; Liu, Changwen; Wang, Xia; Zhang, Jian

    2015-05-01

    To understand the engine main bearings' working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic(TEHD) reaction on engine main bearings is investigated. The calculated method of main bearing's thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic(EHD) and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings.

  16. Research of Two Different Impulsive Faults of Rolling Element Bearing

    Fans and pumps are key machines in process industries such as petrochemical and petroleum industries. Their faults can be catastrophic and result in costly downtime. Bearing fault is almost the most common fault of fans and pumps as rolling element bearings are widely used in these machines. Hence, condition monitoring and diagnosis of bearings are important. Two different impulsive faults of bearings have been observed and studied in previous research. The first fault presents very clear impulsive symptom in envelope spectrum, but the bearing can work for a long time. The other fault shows relatively indistinct symptom, but the bearing will break down in a short time. To overcome the problems of inaccurate diagnosis, a combinational approach based on an impulsive energy indicator and traditional enveloping analysis is proposed in this paper. This approach discriminate these two faults well and can support the maintenance decision for the machines with rolling element bearings.

  17. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation...... performance of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure...

  18. A Nonlinear Elastic Model for Triaxial Compressive Properties of Artificial Methane-Hydrate-Bearing Sediment Samples

    Tsutomu Yamaguchi

    2012-10-01

    Full Text Available A constitutive model for marine sediments containing natural gas hydrate is essential for the simulation of the geomechanical response to gas extraction from a gas-hydrate reservoir. In this study, the triaxial compressive properties of artificial methane-hydrate-bearing sediment samples reported in an earlier work were analyzed to examine the applicability of a nonlinear elastic constitutive model based on the Duncan-Chang model. The presented model considered the dependences of the mechanical properties on methane hydrate saturation and effective confining pressure. Some parameters were decided depending on the type of sand forming a specimen. The behaviors of lateral strain versus axial strain were also formulated as a function of effective confining pressure. The constitutive model presented in this study will provide a basis for an elastic analysis of the geomechanical behaviors of the gas-hydrate reservoir in the future study, although it is currently available to a limited extent.

  19. Performance of passive target tracking using bearing-frequency and bearings of multiple arrays

    DU Xuanmin; YAO Lan

    2002-01-01

    Two target motion analysis (TMA) methods using multi-dimension information are studied, one is TMA with bearing-frequency and the other is TMA with multiple arrays. The optimization algorithm combining Gauss-Newton (G-N) method with Levenberg-Marquardt(LM) method is applied to analyze the performance of target tracking with maximum likelihood estimation(MLE), and Monte Carlo experiments are presented. The results show that although the TMA with multi-dimension information have eliminated the maneuvers needed by conventional bearing-only TMA, but the application are not of universality.

  20. Method of recertifying a loaded bearing member

    Allison, Sidney G. (Inventor)

    1992-01-01

    A method is described of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasonic tone burst generated by a first pulsed phased locked loop (P2L2) equipment configuration. Once a lock point number S is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using a second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor F02=((F1-F3)/F1) 1000000. Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship (-1000000)CI(((F2-F4)/F2)-Fo2), wherein CI is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.

  1. Flexure Based Linear and Rotary Bearings

    Voellmer, George M. (Inventor)

    2016-01-01

    A flexure based linear bearing includes top and bottom parallel rigid plates; first and second flexures connecting the top and bottom plates and constraining exactly four degrees of freedom of relative motion of the plates, the four degrees of freedom being X and Y axis translation and rotation about the X and Y axes; and a strut connecting the top and bottom plates and further constraining exactly one degree of freedom of the plates, the one degree of freedom being one of Z axis translation and rotation about the Z axis.

  2. Bear Creek Project. Final environmental statement

    The Bear Creek Project consists of certain mining and milling operations involving uranium ore deposits located in Converse County, Wyoming. Mining of uranium from nine known ore bodies will take place over a period of ten years (estimated); a mill with a nominal capacity of 1000 tons per day of ore will be constructed and operated as long as ore is available. The waste material (tailings) from the mill, also produced at a rate of about 1000 tons per day, will be stored onsite in an impoundment. Environmental impacts and adverse effects are summarized

  3. Are organohalogen contaminants a bears (Ursus maritimus)?

    Sonne, Christian; Dietz, Rune; Leifsson, PS;

    2006-01-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver......PBDE, polychlorinated biphenyl, and hexachlorocyclohexane concentrations. The lesions were consistent with those reported previously in highly OHC-contaminated Baltic seal populations and exposed laboratory animals. The renal lesions were a result of aging. However, based on the above statistical findings as well as...... health status among wildlife populations and humans relying on food resources that are contaminated with OHCs....

  4. Spectral properties and identification of aerostatic bearings

    Kozánek, Jan; Půst, Ladislav

    2011-01-01

    Roč. 27, č. 1 (2011), s. 63-67. ISSN 0567-7718. [International Conference on Dynamical Systems - Theory and Applications /10./. Lodz, 07.12.2009-10.12.2009] R&D Projects: GA ČR GA101/09/1522 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * identification * stiffness * damping coefficients Subject RIV: BI - Acoustics Impact factor: 0.860, year: 2011 http://www.springerlink.com/content/34l382r75g8wu716/

  5. Carbon Segregation of Bearing Steel Concasting Billet

    2000-01-01

    The formation mechanism of “white band” and central carbon segregation of high-carbon Cr bearing steel concasting billets are discussed in this paper. The maximum oxygen content in the steel produced by concasting process was 13x10-6 with an average oxygen content of 9.3x 10-6.Comparison of metallurgical quality and fatigue property between the concasting steel (CC) andingot casting steel (IC) showed that the carbon segregation (C/C0) in former steel was 0.92~1.10and its fatigue life was equal to that of the latter steel.

  6. Bearing capacity of mixed soil model

    Mehdi Khodashenas Pelkoo

    2009-01-01

    Full Text Available The main objective of this research is improvement of red soil with addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to assess the behavior of red soil, when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC. Safe bearing capacity of all models, have been calculated to identify best and worst soil mixed model.

  7. Coronal properties of planet-bearing stars

    Poppenhaeger, K.; Robrade, J.; Schmitt, J. H. M. M.

    2010-01-01

    Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime, conclusive observational evidence is still missing. We want to establish a sound observational basis to confirm or reject major effects of Star-Planet Interactions (SPI) in stellar X-ray emissions. We therefore conduct a statistical analysis of stellar X-ray activity of all known planet-bearing stars within 30pc di...

  8. Mechatronic stand for gas aerostatic bearing measurement

    Steinbauer, P.; Kozánek, Jan; Neusser, Z.; Šika, Z.; Bauma, V.

    Berlin: Springer, 2008 - (Jablonski, R.; Turkowski, M.; Szewczyk, R.), s. 438-442 ISBN 978-3-540-73955-5. [International Symposium Mechatronics /7./. Waršava (PL), 19.09.2007-21.09.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : gas aerostatic bearings * dynamical experiments * identification of stiffness and damping Subject RIV: BI - Acoustics http://www.springer.com/engineering/ robotics /book/978-3-540-73955-5

  9. Longitudinal misalignment based strain sensor

    Andrews, Jeffrey Pratt

    1989-01-01

    A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated ...

  10. Estimating Potential Effects of Hypothetical Oil Spills on Polar Bears

    Amstrup, Steven C.; Durner, G.M.; McDonald, T.L.; Johnson, W.R.

    2006-01-01

    Much is known about the transport and fate of oil spilled into the sea and its toxicity to exposed wildlife. Previously, however, there has been no way to quantify the probability that wildlife dispersed over the seascape would be exposed to spilled oil. Polar bears, the apical predator of the arctic, are widely dispersed near the continental shelves of the Arctic Ocean, an area also undergoing considerable hydrocarbon exploration and development. We used 15,308 satellite locations from 194 radiocollared polar bears to estimate the probability that polar bears could be exposed to hypothetical oil spills. We used a true 2 dimensional Gausian kernel density estimator, to estimate the number of bears likely to occur in each 1.00 km2 cell of a grid superimposed over near shore areas surrounding 2 oil production facilities: the existing Northstar oil production facility, and the proposed offshore site for the Liberty production facility. We estimated the standard errors of bear numbers per cell with bootstrapping. Simulated oil spill footprints for September and October, the times during which we hypothesized effects of an oil-spill would be worst, were estimated using real wind and current data collected between 1980 and 1996. We used ARC/Info software to calculate overlap (numbers of bears oiled) between simulated oil-spill footprints and polar bear grid-cell values. Numbers of bears potentially oiled by a hypothetical 5912 barrel spill (the largest spill thought probable from a pipeline breach) ranged from 0 to 27 polar bears for September open water conditions, and from 0 to 74 polar bears in October mixed ice conditions. Median numbers oiled by the 5912 barrel hypothetical spill from the Liberty simulation in September and October were 1 and 3 bears, equivalent values for the Northstar simulation were 3 and 11 bears. In October, 75% of trajectories from the 5912 barrel simulated spill at Liberty oiled 9 or fewer bears while 75% of the trajectories affected 20 or

  11. ConStrains identifies microbial strains in metagenomic datasets.

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-10-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  12. Mechanistic modeling of bearing pad to pressure tube contact under localized high temperature conditions in a CANDU fuel channel

    During a postulated critical break LOCA (loss of coolant accident) in a CANDU reactor the coolant flow rates in the fuel channels of the flow pass of the reactor core downstream of the pipe break can rapidly reduce to very low values and remain very low for a period of tens of seconds following the break. Under the sustained low flow conditions, the fuel sheath (cladding) temperature in the affected channels rapidly increases and the coolant in the channels becomes significantly voided. The pressure tubes in the affected pass heat up under a combination of convection heat transfer from the low flows of superheated seam and thermal radiation heat transfer from the hot fuel. Additionally, hot spots may develop on the inner surface of pressure tubes at locations where the fuel bearing pads are in direct contact with the pressure tube. Localized thermal creep strain deformation at the hot spots is a potential pressure tube failure mechanism which could challenge fuel channel integrity. This paper evaluates the local thermal-mechanical deformation of a pressure tube in a CANDU reactor under critical break LOCA conditions tube using a coupled thermal-mechanical finite element COMSOL multi-physics model and investigates the conditions resulting in fuel channel failure due to localized contact between bearing pad and pressure. The mechanistic models are validated against data obtained from COG funded experiments performed at WRL (Whiteshell Research Laboratory). Multiphysics calculations are performed in which the heat transfer, thermal-mechanical and creep strain equations are solved, simultaneously. Heat conduction from bearing pads to the inner surface of the pressure tube is modeled with appropriate convective and radiation heat transfer boundary conditions. Thermal creep strain deformation of the Zr-2.5%Nb pressure tube is modeled using correlations derived from separate uniaxial tests that are reported in the literature. Contact conductance models based on

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

    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.

  14. Qualification of high damping seismic isolation bearings for the ALMR

    The Advanced Liquid Metal Reactor (ALMR) seismic isolation system consists of high damping steel-laminated elastomeric bearings. This type of bearing is used worldwide to isolate buildings and large critical components. A comprehensive testing program has been developed to qualify the use of this system for the ALMR. The program includes material characterization tests, various scale bearing tests, full-size bearing tests, shake table tests, and long-term aging tests. The main tasks and objectives of this program are described in the paper. Additionally, a detailed assessment of completed ALMR bearing test results will be provided. This assessment will be mainly based on half-scale bearing tests performed at the Earthquake Engineering Research Center (EERC) of the University of California at Berkeley and at the Energy Technology Engineering Center (ETEC). These tests were funded by the U.S. Department of Energy (DOE). Both static and dynamic tests were performed. Bearings with two types of end connections were tested: dowelled and bolted. The parameters examined will include the vertical, horizontal stiffness and damping of the bearings under different loading conditions up to failure. This will determine the available margins in the bearings above the design vertical load and horizontal displacement. Additionally, the self-centering capability of the bearings after an earthquake will be addressed. On the basis of these findings, recommendations can be made if necessary, to improve current manufacturing procedures, quality control, and procurement specifications. (author)

  15. Experimental study on bearing preload optimum of machine tool spindle

    An experimental study is conducted to investigate the possibility and the effect of temperature rise and vibration level of bearing by adjusting axial preloads and radial loads in spindle bearing test rig. The shaft of the test rig is driven by a motorized high speed spindle at the range of 0∼20000 rpm. The axial preloads and radial loads on bearings are controlled by using hydraulic pressure which can be adjusted automatically. Temperature rise and radial vibration of test bearings are measured by thermocouples and Polytec portable laser vibrometer PDV100. Experiment shows that the temperature rise of bearings is nonlinear varying with the increase of radial loads, but temperature rise almost increases linearly with the increase of axial preload and rotating speed. In this paper, an alternate axial preload is used for bearings. When the rotating speed passes through the critical speed of the shaft, axial preload of bearings will have a remarkable effect. The low preload could reduce bearing vibration and temperature rise for bearings as well. At the others speed, the high preload could improve the vibration performance of high speed spindle and the bearing temperature was lower than that of the constant pressure preload spindle.

  16. The strained state cosmology

    Tartaglia, Angelo

    2016-01-01

    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time reproduces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  17. Relationship between Helicobacterpylori bearing the cytotoxin associated gene-A and cerebral infarction

    Li Yajun; An Eenglian; Zhu Yongqing; MaoXiaolin; Wang Yumei

    2000-01-01

    Objective To explore the relationship between virulent Helicobacter pylori strains infection and cerebral infarction. Method We assessed the prevalence of infection by strains bearing the cytotoxin -associated gene-A(Cag-A),a strong virulence factor ,in 83 patients with cerebral infarction and in 71 age- and sex-matched controls with similar social background. Result Prevalence of Helicobacter pylori infection was significantly higher in patients than in controls(78.3% versus 56.3%,p<0.05),with an odds ratio of 2.8(95%CI,1.46 to 5.36) adjusted for age, sex, main stroke factors. Patients with cerebral infarction also had a higher prevalence of Cag-A-positive strains(45.8% versus 19.7%, P<0.01),with an adjusted odds ratio of 3.43(95%CI 1.5 to 7.24).Conclusion It was suggested that chronic Helicobacter pylori infection, especially Cag-A-positive strains infection is an independent risk factor for cerebral infarction.

  18. Non-fuel bearing hardware melting technology

    Battelle has developed a portable hardware melter concept that would allow spent fuel rod consolidation operations at commercial nuclear power plants to provide significantly more storage space for other spent fuel assemblies in existing pool racks at lower cost. Using low pressure compaction, the non-fuel bearing hardware (NFBH) left over from the removal of spent fuel rods from the stainless steel end fittings and the Zircaloy guide tubes and grid spacers still occupies 1/3 to 2/5 of the volume of the consolidated fuel rod assemblies. Melting the non-fuel bearing hardware reduces its volume by a factor 4 from that achievable with low-pressure compaction. This paper describes: (1) the configuration and design features of Battelle's hardware melter system that permit its portability, (2) the system's throughput capacity, (3) the bases for capital and operating estimates, and (4) the status of NFBH melter demonstration to reduce technical risks for implementation of the concept. Since all NFBH handling and processing operations would be conducted at the reactor site, costs for shipping radioactive hardware to and from a stationary processing facility for volume reduction are avoided. Initial licensing, testing, and installation in the field would follow the successful pattern achieved with rod consolidation technology

  19. Load bearing capacity of degraded nuclear piping

    Integrity assessment of piping components with postulated cracks is important for safe and reliable operation of power plants. While various equations and methods are available for prediction of the load bearing capacity of pipes and elbows, it is very important to choose the correct equation and method whose predictions are consistent, safe but not too conservative with respect to the experimental results. Towards this goal, a comprehensive Component Integrity Assessment Program was initiated under a joint MPA-BARC collaborative program where a large number of austenitic and ferritic pipes and elbows of nominal diameter of 50-400 mm with various crack configurations and sizes were tested. These test results along with results of previous tests were analysed with various available limit load equations present and also with the R6 method. Based on the comparison of these test results and predictions, the correct equation and method are recommended to reliably predict the load bearing capacity of flawed pipes and elbows reliably. (authors)

  20. Individual effects of seasonal changes, visitor density, and concurrent bear behavior on stereotypical behaviors in captive polar bears (Ursus maritimus).

    Kelly, Krista R; Harrison, Michelle L; Size, Daniele D; MacDonald, Suzanne E

    2015-01-01

    Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy. PMID:24933263

  1. Variation in M protein production among Streptococcus pyogenes strains according to emm genotype.

    Matsumoto, Masakado; Suzuki, Masahiro; Hirose, Kaoru; Hiramatsu, Reiji; Minagawa, Hiroko; Minami, Masaaki; Tatsuno, Ichiro; Okamoto, Akira; Ohta, Michio; Hasegawa, Tadao

    2011-06-01

    M protein is an important virulence determinant in Streptococcus pyogenes, but the amounts of M protein in various strains of the species remain to be elucidated. To assess the amount of M protein in strains of each emm genotype, dot blot analysis was performed on 141 clinically isolated strains. Among the cell membrane-associated proteins, M protein was present in greater quantities in the emm1, 3, and 6 strains than in the other emm strains. In addition three strains, one each of the emm1, 3, and 6 types, showed prolific M protein production (M protein-high producers). These three emm genotypes are frequently isolated in clinical practice. Sequencing of the csrRS gene, one of the two-component signal transduction systems implicated in virulence, was performed on 25 strains bearing different amounts of M protein. CsrS mutations, in contrast to CsrR protein, were detected in 11 strains. The M protein-high producer strain of emm1 type carried two amino acid substitutions, whereas the other three emm1 strains carried only one substitution each. The M protein-high producer expressed its emm gene more strongly than the corresponding M protein-low producer did according to TaqMan RT-PCR. These observations suggest that the accumulation of amino acid substitutions in CsrS protein may contribute, at least in part, to the large amount of M protein production seen in several emm genotypes. PMID:21371090

  2. Detection of bearing damage by statistic vibration analysis

    Sikora, E. A.

    2016-04-01

    The condition of bearings, which are essential components in mechanisms, is crucial to safety. The analysis of the bearing vibration signal, which is always contaminated by certain types of noise, is a very important standard for mechanical condition diagnosis of the bearing and mechanical failure phenomenon. In this paper the method of rolling bearing fault detection by statistical analysis of vibration is proposed to filter out Gaussian noise contained in a raw vibration signal. The results of experiments show that the vibration signal can be significantly enhanced by application of the proposed method. Besides, the proposed method is used to analyse real acoustic signals of a bearing with inner race and outer race faults, respectively. The values of attributes are determined according to the degree of the fault. The results confirm that the periods between the transients, which represent bearing fault characteristics, can be successfully detected.

  3. A Review on Prognosis of Rolling Element Bearings

    N.S. Jammu

    2011-10-01

    Full Text Available Bearings are amongst the frequently encountered components to be found in rotating machinery. Though inexpensive, their failure can interrupt the production in a plant causing unscheduled downtime and production losses. So the bearing prognosis plays a significant role in reducing plant down time and enhanced operation safety, by estimating the Remaining Useful Life (RUL of damaged bearing. Admitting the importance of bearing prognosis, this literature reviewattempts to summarize various techniques, methods and models used in the prognosis of bearing till date. The definition of bearing prognosis is discussed in the beginning, followed by classification ofvarious prognostic methods, review of methods used by various investigators in this research domain and concluding the topic with the summary of future research directions.

  4. On the future of controllable fluid film bearings

    Santos, Ilmar

    2011-01-01

    This work gives an overview of the theoretical and experimental achievements of mechatronics applied to fluid film bearings. Compressible and uncompressible fluids are addressed. Rigid and elastic (deformable) bearing profiles are investigated. Hydraulic, pneumatic, magnetic and piezoelectric...... controllable fluid film bearings is to improve the overall machine performance by: controlling the lateral vibration of rigid and flexible rotating shafts; modifying bearing dynamic characteristics, such as stiffness and damping properties; increasing the rotational speed ranges by enhancing damping and...... eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing start-up torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable fluid film bearings can act as “smart” machine components and be applied to...

  5. Wear fault diagnosis of an emulsion pump crank bearing

    HAN Xiao-ming; DU Chang-long; ZHANG Yong-zhong; TIE Zhan-xu

    2008-01-01

    The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism.The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the bearing axis was obtained. As the crank bearing gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank bearing can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.

  6. Improvement of design technique of track machines bodies bearing structures

    Bogdan TOVT

    2012-01-01

    Full Text Available The paper is devoted to improvement of design technique of track machines bodies bearing structures. The review and analysis of state-of-the-art of the mathematical programming theory and the optimal designing are done. The numerical optimization procedure for track machines bodies bearing structures is proposed. The approbation of the proposed procedure is taken on structural optimization problems. Mathematical aspects of proposed procedure implementation are investigated, particularly the algorithm convergence and the sensitivity analysis of initial designs.Deflected mode of the ballast leveling machine SPZ-5/UA body bearing structure was investigated analytically (FEM study and experimentally (trial running inspection on durability. The necessity of optimization implementation for bodies bearing structures is substantiated. The rational design of track machine SPZ-5/UA bearing structure was obtained with the numerical optimization procedure proposed in the paper. The deflected mode of the body rational bearing structure was investigated.

  7. The R and D D's bearing test benches

    In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author)

  8. A Low Friction Thrust Bearing for Reciprocating Compressors

    Nagata, Shuhei; Kousokabe, Hirokatsu; Sekiyama, Nobuya; Ono, Toshiaki

    2012-01-01

    A thrust bearing with a micro texture on its sliding surface that produces hydrodynamic pressure was developed for use in reciprocating compressors. Evaluation using an elemental friction test showed that its friction loss was 20–60 % lower than that of the current design. Measurement of the efficiency of a compressor with the developed thrust bearing showed that the coefficient of performance was 1.4 % higher than that of a compressor with a conventional thrust bearing.

  9. A magnetic bearing based on eddy-current repulsion

    Nikolajsen, J. L.

    1987-01-01

    This paper describes a new type of electromagnetic bearing, called the Eddy-Current Bearing, which works by repulsion between fixed AC-electromagnets and a conducting rotor. The following advantages are expected: inherent stability, higher load carrying capacity than DC-electromagnetic bearings, simultaneous radial, angular and thrust support, motoring and generating capability, and backup mode of operation in case of primary power failure. A prototype is under construction.

  10. Suppression of Base Excitation of Rotors on Magnetic Bearings

    Steven Marx; C. Nataraj

    2007-01-01

    This paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional, and differential feedback control. A four-degree-of-freedom model is used for the rotor system, and the bearings are ...

  11. Variable viscosity condition in the modeling of a slider bearing

    Uprety, Kedar Nath; Mancas, Stefan C.

    2014-01-01

    To reduce tear and wear of machinery lubrication is essential. Lubricants form a layer between two surfaces preventing direct contact and reduce friction between moving parts and hence reduce wear. In this short letter the lubrication of two slider bearings with parallel and nonparallel is studied. First, we show that bearings with parallel plates cannot support any load. For bearings with nonparallel plates we are interested on how constant and temperature dependent viscosity affects the pro...

  12. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    Nittmannová Ľubica; Magura Martin

    2016-01-01

    The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types ...

  13. Food availability and foraging near human developments by black bears

    Merkle, Jerod A.; Robinson, Hugh S.; Krausman, Paul R.; Alaback, Paul B.

    2013-01-01

    Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

  14. The peculiarities of bear numbers dynamics in the Eastern Carpathians

    Khoyetskyy, Pavlo

    2013-01-01

    There have been two periods of change in the dynamics of bear population in the Eastern Carpathians. The first period lasted over 50 years, starting in the late 1940s and ending in the year 2001. The second period started in the early 21st century. The bear population reached its maximum – of about 1100 individuals – in the early 1970s. Over 85% of recorded bear deaths have resulted from poaching.

  15. Household Portfolios and Risk Bearing over Age and Time

    Alessandro Bucciol; Raffaele Miniaci

    2011-01-01

    We exploit the US Survey of Consumer Finances from 1998 to 2007 to study households’ portfolio risk bearing. We compare four alternative measures of risk, two based on a financial portfolio and two based on a broader portfolio also including – as illiquid assets – human capital, real estate, business wealth and related debt. The measures provide a different ranking of household risk bearing, but they consistently show that risk bearing fell after 2001, and it positively correlates with wealth...

  16. Spatial Distribution of Black Bear Incident Reports in Michigan.

    Jamie E McFadden-Hiller

    Full Text Available Interactions between humans and carnivores have existed for centuries due to competition for food and space. American black bears are increasing in abundance and populations are expanding geographically in many portions of its range, including areas that are also increasing in human density, often resulting in associated increases in human-bear conflict (hereafter, bear incidents. We used public reports of bear incidents in Michigan, USA, from 2003-2011 to assess the relative contributions of ecological and anthropogenic variables in explaining the spatial distribution of bear incidents and estimated the potential risk of bear incidents. We used weighted Normalized Difference Vegetation Index mean as an index of primary productivity, region (i.e., Upper Peninsula or Lower Peninsula, primary and secondary road densities, and percentage land cover type within 6.5-km2 circular buffers around bear incidents and random points. We developed 22 a priori models and used generalized linear models and Akaike's Information Criterion (AIC to rank models. The global model was the best compromise between model complexity and model fit (w = 0.99, with a ΔAIC 8.99 units from the second best performing model. We found that as deciduous forest cover increased, the probability of bear incident occurrence increased. Among the measured anthropogenic variables, cultivated crops and primary roads were the most important in our AIC-best model and were both positively related to the probability of bear incident occurrence. The spatial distribution of relative bear incident risk varied markedly throughout Michigan. Forest cover fragmented with agriculture and other anthropogenic activities presents an environment that likely facilitates bear incidents. Our map can help wildlife managers identify areas of bear incident occurrence, which in turn can be used to help develop strategies aimed at reducing incidents. Researchers and wildlife managers can use similar mapping

  17. Design of load-bearing elements of a multiresidental building

    Klopčič, gradbenik, Jure

    2012-01-01

    This thesis presents the design and analysis of load-bearing elements in a four storey multiresidental building according to current Eurocode standards for the design of building structures. Load-bearing elements, composed of monolith reinforced concrete, are slabs, separated walls, walls with openings and pillars. In the analysis of the load-bearing structure the influence of permanent and variable weight and also the impact of wind, snow and earthquake are considered. Detailed analysis of v...

  18. MOBILE TIBIAL POLYETHYLENE BEARING IN TOTAL KNEE ARTHROPLASTY

    de Araújo Barros Cobra, Hugo Alexandre; da Palma, Idemar Monteiro

    2015-01-01

    Debris of polyethylene tibial bearings have been recognized as a major cause for the onset of the cascade of biological events leading to osteolysis and loosening of prosthetic components after total knee arthroplasty. Since then, research has been focused on alternative bearing surfaces in order to minimize the amount and rate of polyethylene wear off and, in doing so, increasing the survivorship rate for knee arthroplasties. One such option is to have a mobile tibial bearing allowing more c...

  19. Fatigue Crack Initiation and Propagation of Aluminum Alloy Bearings

    CHENG Xian-Hua; MA Yan-Yan

    2004-01-01

    Observation of fatigue crack initiation and propagation during fatigue test in ALSn20Cu bearing has been presented. Journal center orbit, oil film pressure and stress distribution in alloy layer have been calculated and are taken as the basis for theoretically simulating the bearing fatigue process. It is found that the calculated results are in good accordance with the experimental results, which provides a feasible way for investigation of fatigue crack propagation process in the bearing.

  20. A MICRO TURBINE DEVICE WITH ENHANCED MICRO AIR-BEARINGS

    Shan, X.-C.; Zhang, Qide; Sun, Y. F.; Maeda, R

    2006-01-01

    As part of progress in developing a micro gas turbine engine, this paper presents the design, fabrication and testing of a silicon-based micro turbine device, which is driven by compressed air. To improve its rotational speed and stability, the turbine device has enhanced journal air bearing and thrust air bearings. The thrust air bearings are utilized for supporting the rotor from both its top- and bottom- sides. The top thrust air bearing employs pump-in type spiral grooves, and the bottom ...

  1. Numerical Analysis of Nonlinear Rotor-bearing-seal System

    CHENG Mei; MENG Guang; JING Jian-ping

    2008-01-01

    The system state trajectory, Poincaré maps, largest Lyapunov exponents, frequency spectra and bifurcation diagrams were used to investigate the non-linear dynamic behaviors of a rotor-bearing-seal coupled system and to analyze the influence of the seal and bearing on the nonlinear characteristics of the rotor system. Various nonlinear phenomena in the rotor-bearing-seal system, such as periodic motion, double-periodicmotion, multi-periodic motion and quasi-periodic motion were investigated. The results may contribute to a further understanding of the non-linear dynamics of the rotor-bearing-seal coupled system.

  2. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  3. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  4. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  5. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    Nittmannová Ľubica

    2016-03-01

    Full Text Available The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types of bearings.

  6. Wear Performance of Ceramic-On-Metal Hip Bearings

    Jörn Reinders; Robert Sonntag; Christian Heisel; Tobias Reiner; Leo Vot; Jan Philippe Kretzer

    2013-01-01

    Ceramic-on-metal (CoM) bearings are considered to be a promising alternative to polyethylene-based bearings or hard-on-hard bearings (Ceramic-on-Ceramic (CoC) and Metal-on-Metal (MoM)). Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results. This may be related to limitations of wear-measuring methods. Therefore, the aim of this study was to improve the gravimetric measurement technique and to test wear behaviour of CoM bearings compared to Co...

  7. INVESTIGATION OF TRIBOLOGICAL PROPERTIES CuSn10 BEARING MATERIAL

    Bekir Sadık ÜNLÜ

    2005-01-01

    Full Text Available Bronzes which copper based alloys is widely used because of properties physical, thermal and tribological as journal bearing material. This material that has tribological performance good conclusions gives at journal bearings. In this study, CuSn10 bronze that were manufactured journal bearings friction and wear properties has been examined and compared. SAE 1050 steel shaft has been used as counter abrader. Experiments have been carried out 10 N and 20 N loads, 750 and 1500 rpm, dry and lubricated conditions by using radial journal bearing wear test rig. As a results, high friction coefficient and weigh loss have been obtained at dry condition more than lubricated condition.

  8. Targeting Faulty Bearings for an Ocean Turbine Dynamometer

    David J. Vendittis

    2013-01-01

    Full Text Available A real-time, vibrations-based condition monitoring method used to detect, localize, and identify a faulty bearing in an ocean turbine electric motor is presented in this paper. The electric motor is installed in a dynamometer emulating the functions of the actual ocean turbine. High frequency modal analysis and power trending are combined to assess the operational health of the dynamometer’s bearings across an array of accelerometers. Once a defect has been detected, envelope analysis is used to identify the exact bearing containing the defect. After a brief background on bearing fault detection, this paper introduces a simplified mathematical model of the bearing fault, followed with the signal processing approach used to detect, locate, and identify the fault. In the results section, effectiveness of the methods of bearing fault detection presented in this paper is demonstrated through processing data collected, first, from a controlled lathe setup and, second, from the dynamometer. By mounting a bearing containing a defect punched into its inner raceway to a lathe and placing an array of accelerometers along the length of lathe, the bearing fault is clearly detected, localized, and identified as an inner raceway defect. Through retroactively trending the data leading to the near-failure of one of the electric motors in the dynamometer, the authors identified a positive trend in energy levels for a specific frequency band present across the array of accelerometers and identify two bearings as possible sources of the fault.

  9. Accurately bearing measurement in non-cooperative passive location system

    The system of non-cooperative passive location based on array is proposed. In the system, target is detected by beamforming and Doppler matched filtering; and bearing is measured by a long-base-ling interferometer which is composed of long distance sub-arrays. For the interferometer with long-base-line, the bearing is measured accurately but ambiguously. To realize unambiguous accurately bearing measurement, beam width and multiple constraint adoptive beamforming technique is used to resolve azimuth ambiguous. Theory and simulation result shows this method is effective to realize accurately bearing measurement in no-cooperate passive location system. (authors)

  10. Numerical investigation of cavitation flow in journal bearing geometry

    Riedel, M.; Schmidt, M.; Stücke, P.

    2013-04-01

    The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  11. Numerical investigation of cavitation flow in journal bearing geometry

    Stücke P.

    2013-04-01

    Full Text Available The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  12. Gene transcription in polar bears (Ursus maritimus) from disparate populations

    Bowen, Lizabeth; Miles, A. Keith; Waters, Shannon C.; Meyerson, Randi; Rode, Karyn D.; Atwood, Todd C.

    2015-01-01

    Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

  13. Platelet function in brown bear (Ursus arctos compared to man

    Särndahl Eva

    2010-06-01

    Full Text Available Abstract Background Information on hemostasis and platelet function in brown bear (Ursus arctos is of importance for understanding the physiological, protective changes during hibernation. Objective The study objective was to document platelet activity values in brown bears shortly after leaving the den and compare them to platelet function in healthy humans. Methods Blood was drawn from immobilized wild brown bears 7-10 days after leaving the den in mid April. Blood samples from healthy human adults before and after clopidogrel and acetylsalicylic acid administration served as control. We analyzed blood samples by standard blood testing and platelet aggregation was quantified after stimulation with various agonists using multiple electrode aggregometry within 3 hours of sampling. Results Blood samples were collected from 6 bears (3 females between 1 and 16 years old and from 10 healthy humans. Results of adenosine diphosphate, aspirin, and thrombin receptor activating peptide tests in bears were all half or less of those in humans. Platelet and white blood cell counts did not differ between species but brown bears had more and smaller red blood cells compared with humans. Conclusion Using three different tests, we conclude that platelet function is lower in brown bears compared to humans. Our findings represent the first descriptive study on platelet function in brown bears and may contribute to explain how bears can endure denning without obvious thrombus building. However, the possibility that our findings reflect test-dependent and not true biological variations in platelet reactivity needs further studies.

  14. Synchronous dynamics of a coupled shaft/bearing/housing system with auxiliary support from a clearance bearing: Analysis and experiment

    Lawen, James L., Jr.; Flowers, George T.

    1995-01-01

    This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing synchronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified.

  15. Novel strained superjunction VDMOS

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.

    2015-09-01

    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  16. Strains in general relativity

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a 'fiducial observer'. We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations

  17. Strains in General Relativity

    Bini, Donato; Geralico, Andrea

    2014-01-01

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a "fiducial observer." We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations.

  18. Handling of tritium-bearing wastes

    The generation of nuclear power and reprocessing of nuclear fuel results in the production of tritium and the possible need to control the release of tritium-contaminated effluents. In assessing the need for controls, it is necessary to know the production rates of tritium at different nuclear facilities, the technologies available for separating tritium from different gaseous and liquid streams, and the methods that are satisfactory for storage and disposal of tritiated wastes. The intention in applying such control technologies and methods is to avoid undesirable effects on the environment, and to reduce the radiation burden on operational personnel and the general population. This technical report is a result of the IAEA Technical Committee Meeting on Handling of Tritium-bearing Effluents and Wastes, which was held in Vienna, 4 - 8 December 1978. It summarizes the main topics discussed at the meeting and appends the more detailed reports on particular aspects that were prepared for the meeting by individual participants

  19. Load Bearing Innovative Construction from Glass

    Kalamar, R.; Eliášová, M.

    2015-11-01

    Glass plays an exceptional role in the modern architecture due to the optical properties and transparency. Structural elements from glass like beams, facades and roofs are relatively frequent in common practice [1]. Although glass has significantly higher compressive strength in comparison with tensile strength, load bearing glass elements are relatively rare. This opens up new opportunities for application of glass in such structures as transparent columns loaded by the axial force. This paper summarizes the experimental results of the tests on glass columns loaded by centric pressure, which were performed in the laboratories of the CTU in Prague, Faculty of Civil Engineering. The first set of experiments was composed of three specimens in a reduced scale 1:2 to verify real behaviour of the specimens with enclosed hollow cross-section. The main goal of the experiment was to determine force at the first breakage and consequently the maximal force at the collapse of this element.

  20. Mastication forces and implant-bearing surface.

    Le Gall, M G; Lauret, J F; Saadoun, A P

    1994-01-01

    This article discusses the shift of emphasis in implantology from the phenomenon of osseointegration of implants to the accurate fabrication of the prosthesis, recognizing the implant/prosthesis unit as an actual replica rather than a replacement of the missing tooth. The study of kinetics with its succession of mandibular cycles is used to discuss the integration of mastication and occlusion. The importance of periimplant ligament in natural teeth is discussed, along with the impact of its absence on implant mobility. The impact of the bone types and the root surface architecture on the implant-bearing surface is presented along with the stress of the mastication forces. All these factors have to be considered in the treatment planning and effectively communicated to the laboratory. The learning objective of this article is to provide updated information in those areas for the reader. PMID:7488751

  1. Pooh Bear rock and Mermaid Dune

    1997-01-01

    One of the two forward cameras aboard Sojourner imaged this area of Martian terrain on Sol 26. The large rock dubbed 'Pooh Bear' is at far left, and stands between four and five inches high. Mermaid Dune is the smooth area stretching horizontally across the top quarter of the image. The Alpha Proton X-Ray Spectrometer (APXS) instrument aboard Sojourner will be deployed on Mermaid Dune, and the rover will later use its cleated wheels to dig into it.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages and Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  2. Batch fabrication of carbon nanotube bearings

    Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes (MWNTs) can be used as a robust nanoscale motion enabling mechanism. Here, we report on a novel method suited for structuring large arrays of MWNTs into such nanobearings in a parallel fashion. By creating MWNT nanostructures with nearly identical electrical circuit resistance and heat transport conditions, uniform Joule heating across the array is used to simultaneously engineer the shell geometry via electric breakdown. The biasing approach used optimizes process metrics such as yield and cycle-time. We also present the parallel and piecewise shell engineering at different segments of a single nanotube to construct multiple, but independent, high density bearings. We anticipate this method for constructing electromechanical building blocks to be a fundamental unit process for manufacturing future nanoelectromechanical systems (NEMS) with sophisticated architectures and to drive several nanoscale transduction applications such as GHz-oscillators, shuttles, memories, syringes and actuators

  3. Toxicity of Magnetic Albumin Microspheres Bearing Adriamycin

    2000-01-01

    Magnetic albumin microspheres bearing adriamycin (ADM-MAM) is a novel chemotherapeutic compound with site-specific drug delivery characteristics. The acute and subacute toxic tests of the compound, local irritating test and anaphylactic test were performed on mice and guinea pigs. The results showed there was no macroscopically and microscopically direct cytotoxic injuries of the compound to the animal organs or to the cells. The LD50 value of the compound was higher than that of the single used adriamycin, indicating that the compound was less toxic than the single adriamycin and quite safe in its therapeutic dosage. Furthermore, there was also no side effects or toxic reactions to be observed on clinical patients with advanced carcinoma or gastric cancer.

  4. Bear Creek Project. Draft environmental statement

    The Bear Creek Project consists of mining and milling operations involving uranium ore deposits located in Converse County, Wyoming. Mining of uranium from six known ore bodies will take place over ten years; a 1000 tons ore/day will be constructed and operated as long as ore is available. The tailings will be stored onsite in an impoundment. The project would convert 2700 acres from grazing use to mining/milling activities for about ten years. Mining would disturb a total of 1600 acres but, because of reclamation, the max acreage disturbed at any one time would be about 1000 acres, the average being about 650 acres. Dose rates were computed for an individual in a ranch house at the nearest ranch. Conditions for the protection of the environment are proposed. Possible environmental impacts evaluated cover air, land, water, soil, vegetation, wildlife, and community. A benefit-cost analysis is made

  5. Geodetic surveying of strains

    Meixner, H.

    1980-11-01

    This article evaluates methods and apparatus used in the German Democratic Republic to assess vertical and horizontal deformations and strains caused by coal mining and mining of other deposits. Each of the methods is characterized; type of measuring apparatus and its accuracy is given. The following conventional methods of surveying are characterized: (I.) vertical strains: measurement with hydrostatic tube balance (apparatus produced by the Praezisionsmechanik Freiberg, with accuracy of 0.01 mm), trigonometric levelling (error up to 10 mm), geometric levelling (NI 007 and NI 008 apparatus produced by Carl Zeiss JENA), and direct height measuring; (II.) horizontal strains: direct surveying with accuracy higher than 5 mm/50 m, indirect surveying (theodolite THEO 010 A produced by the Carl Zeiss JENA), and alignment method (using apparatus produced by Praezisionsmechanik, Freiberg). Advanced surveying methods are also discussed: electro-optical method (using EOK 2000 range finder produced by Carl Zeiss JENA, with average error ranging from 5 mm to 10 mm), laser method (LF-1 and LFG-1 lasers produced by Carl Zeiss JENA), measuring gyroscope used to measure contorsion (MRK 2 gyroscope produced by the Praezisionsmechanik, Freiberg); photogrammetry: stereophotogrammetry and so-called parallel photogrammetry. (15 refs.) (In Polish)

  6. Study of a four Titled Pad Bearing

    Ibrahim A. Mohsen

    2013-05-01

    Full Text Available This research deal with an analytical study of a four titled pad bearing. These pads are arranged around the journal. A computer program has been used to solve Reynolds equation numerically using the finite difference technique.            The results showed that, the non dimensional force is increased with the increase of the non dimensional load and the gradient of the curve is increased with the decrease of the ( ratio. while the gradient is decreased with the increase of the number of pads which gives less power absorption due to the decrease of the friction force.            Also the results showed  that the eccentricity ratio is in the range of (0.4-0.8 and the maximum attitude angle is (43o. The curve of the relation between the eccentricity ratio and the load number does not start from the zero.            It has been noticed that the increase of the friction factor cause an increase in Summerfield number and the curve gradient is increase with the decrease of the ( ratio. Also the gradient is increased for a fixed value of the ( ratio with the decrease of external load, where as the decrease of the ( ratio cause a decrease of the oil film thickness and this cause an increase of the shearing rate.             Finally, the oil flow rate is increased with the increase of the ( ratio and this would increased more with the increase of the number of pads for the same value of ( ratio which leads to a decrease of the bearing temperature and this maintain the same value of the oil film thickness due to maintaining the same viscosity for the lubricant.

  7. Temperature controlled strain gaged extensometer

    Ramos, G. L.; Seplow, S.

    1968-01-01

    Temperature controlled strain-gaged extensometer measures longitudinal and girth deflections of pressure vessels in excess of one percent strain during pressurization and depressurization with cryogenic fluids at cryogenic temperatures. The device is of beryllium-copper strips.

  8. Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

    Flowers, George T.

    1995-01-01

    Progress made in the current year is listed, and the following papers are included in the appendix: Steady-State Dynamic Behavior of an Auxiliary Bearing Supported Rotor System; Dynamic Behavior of a Magnetic Bearing Supported Jet Engine Rotor with Auxiliary Bearings; Dynamic Modelling and Response Characteristics of a Magnetic Bearing Rotor System with Auxiliary Bearings; and Synchronous Dynamics of a Coupled Shaft/Bearing/Housing System with Auxiliary Support from a Clearance Bearing: Analysis and Experiment.

  9. Gulf-Wide Information System, Environmental Sensitivity Index Bear Database, Geographic NAD83, LDWF (2001) [esi_bear_LDWF_2001

    Louisiana Geographic Information Center — This data set contains sensitive biological resource data for the Louisiana black bear in coastal Louisiana. Vector polygons represent occupied habitat for this...

  10. Ancestral Polymorphisms and Sex-Biased Migration Shaped the Demographic History of Brown Bears and Polar Bears

    Shigeki Nakagome; Shuhei Mano; Masami Hasegawa

    2013-01-01

    Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA) and matrilineal mitochondrial DNA (mtDNA). Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA) or more than 14 times (mtDNA) larger population sizes than p...

  11. Ancestral polymorphisms and sex-biased migration shaped the demographic history of brown bears and polar bears.

    Shigeki Nakagome

    Full Text Available Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA and matrilineal mitochondrial DNA (mtDNA. Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA or more than 14 times (mtDNA larger population sizes than polar bears and that polar bear lineage is derived from within brown bear diversity. In brown bears, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar bears across aDNA genes and mtDNA.

  12. MEMS Resonant Strain Sensor Integration

    Myers, David Richard

    2010-01-01

    Despite commercial availability since the 1950's, silicon strain sensors have not experienced the same success as other microdevices, such as accelerometers, pressure sensors, and inkjet heads. Strain sensors measure mechanical deformation and could be used in many structural components, improving safety, controls, and manufacturing tolerances. This thesis examines major strain sensing techniques and highlights both advantages and disadvantages of each. MEMS resonant strain gauges are iden...

  13. Analysis of strain and stress in the equine hoof capsule using finite element methods: comparison with principal strains recorded in vivo.

    Thomason, J J; McClinchey, H L; Jofriet, J C

    2002-11-01

    Finite-element (FE) methods have great potential in equine biomechanics in evaluating mechanical stresses and strains in tissues deep within the hoof. In this study, we critically assessed that potential by comparing results of FE analyses of capsular strain with in vivo data. Nine FE models were developed, corresponding to the shape of hooves for which in vivo principal strain data are available. Each model had the wall, laminar junction, sole and distal phalanx (PIII). In a first loading condition (LC1), force is distributed uniformly to the bearing surface of the wall to determine reaction forces and moment on PIII. These reaction forces were subsequently applied to PIII in loading condition 2 (LC2) to simulate loading via the skeleton. Magnitude of the force resultant was equivalent to the vertical force on the hoof at midstance. Principal compressive strains epsilon2 were calculated at the locations of 5 rosette gauges on the real hooves and are compared with the in vivo strains at midstance. FE strains were from 16 to 221% of comparable in vivo values, averaging 104%. All models in this, and reports by other workers, show predominance of stress and strain at the toe to a greater extent than in the real hoof. The primary conclusion is that FE modelling of strain in the hoof capsule or deeper tissues of individual horses should not be attempted without corroborating experimental data. PMID:12455844

  14. Interference-Fit Life Factors for Roller Bearings

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

    2009-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner-ring interference fit. Calculations were performed for up to 7 fit classes for each of 10 bearing sizes. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. A method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings. All calculated lives are for zero initial internal clearance. Any reduction in bearing clearance due to interference fit would be compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate, and heavy loads and interference fits ranging from extremely light to extremely heavy for bearing accuracy class RBEC-5 (ISO class 5). Interference fits on the inner ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference-fit life factors for a particular fit. The tightest fit at the high end of the tolerance band produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  15. Strain calibration of optical FBG-based strain sensors

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  16. Radioresistance transfer by R-factor

    R46 R-factor was transferred to wild-type E. coli K 12 strain E. coli AB 1157 and to its rec mutants recA-, recB-, and recA- recB- double mutants by conjugation. The appearance of R46 R-factor in rec+ and rec- E. coli strains was detected by transferring resistance to ampicillin, streptomycin, tetracyclin and sulfonamids. R46 R-factor slightly increased the survival of the wild-type strain and had no effect on the survival of recA- and recA- recB- double mutants. A well detectable increase in UV and Co-gamma resistance was found in recB- mutant harboring R46 R-factor. R46 R-factor seems to be able to partly compensate the lack of the encoding activity for exonuclease in recB- mutant. (author)

  17. Rotor Bearing System Analysis Using the Transfer Matrix Method with Thickness Assumption of Disk and Bearing

    Ghasemalizadeh, Omid; Mirzaee, Mohammad Reza; Sadeghi, Hossein; Ahmadian, Mohammad Taghi

    2013-01-01

    One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary con...

  18. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    Flowers, George T.; Xie, Huajun; Sinha, S. C.

    1995-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness, and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  19. Precision determination of strains by strain measurement method

    Method for precision strain measurement determination of strains measurement determination of strains by direct measurement of the resistance of strain gauge resistors put on the sample, by constant current bridge MOD-61 of 0.05 class using a zero method by single bridge double-clamp circuit is described. Strain measurement technique was used to investigate residual stresses in tubular samples. Sample external diameter made up 30 mm, the length - 180, the wall thickness-11 mm. To evaluate the method sensitivity, annealed samples were investigated (annealing temperature-850-880 deg C, hold-up-2 h, cooling in the furnace). It is ascertained, that the method provides for 0.3-0.5 μm strain measurement accuracy even if sample strains do not exceed 3.0-3.6 μm and correspond to residual stress level of no more than 20 MPa

  20. Design and Manufacturing Considerations for Shockproof and Corrosion-Immune Superelastic Nickel-Titanium Bearings for a Space Station Application

    DellaCorte, Christopher; Wozniak, Walter A.

    2012-01-01

    An intermetallic nickel-titanium alloy, 60NiTi (60wt%Ni, 40wt%Ti), is a promising tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, easily lubricated and is non-magnetic. It also falls within the class of superelastic alloys and can elastically endure large strains (beyond 5 percent) making it highly resistant to excessive and unexpected (shock) loads. Key material properties and characteristics such as elastic modulus, tensile fracture sensitivity and residual stress behavior, however, differ from conventional alloys such as steel and this significantly affects bearing design and manufacturing. In this paper, the preliminary design and manufacture of ball bearings made from 60NiTi are considered for a highly corrosive, lightly loaded, low speed bearing application found inside the International Space Station s water recycling system. The information presented is expected to help guide more widespread commercialization of this new technology into space mechanism and other applications.

  1. Seasonal carbohydrate storage and mobilization in bearing and non-bearing pistachio (Pistacia vera) trees.

    Spann, Timothy M; Beede, Robert H; Dejong, Theodore M

    2008-02-01

    We analyzed annual carbohydrate storage and mobilization of bearing ("on") and non-bearing ("off") 'Kerman' pistachio (Pistacia vera L.) trees growing on three different rootstocks. On all rootstocks, carbohydrate storage in shoots and branches of "on" and "off" trees was lowest following the spring growth flush. In "off" trees, stored carbohydrates increased and remained high after the initial growth flush. In "on" trees, stem carbohydrates increased temporarily in early summer, but were mobilized in mid-season during kernel fill, and then increased again after nut harvest. During the dormant season, the only substantial differences in carbohydrate storage between previously "on" and "off" trees were found in the roots of the weakest rootstock. The annual carbohydrate storage and mobilization pattern in canopy branches of heavily cropped pistachio trees appeared to be driven by carbohydrate demands related to nut development and untempered by tree vigor. Mobilization of carbohydrates from current-season and 1- and 2-year-old stem wood of "on" trees during the primary period of kernel fill corresponded with the period of inflorescence bud abscission. Thus, the alternate bearing pattern associated with inflorescence bud abscission in 'Kerman' pistachio may be a function of mid-season mobilization of stored carbohydrates in current-season stems resulting in stimulation of inflorescence bud abscission. PMID:18055431

  2. 19 CFR 133.21 - Articles bearing counterfeit trademarks.

    2010-04-01

    ...: “The sample described as and provided pursuant to 19 CFR 133.21(d) was (damaged/destroyed/lost) during... 19 Customs Duties 1 2010-04-01 2010-04-01 false Articles bearing counterfeit trademarks. 133.21... Recorded Trademarks or Recorded Trade Names § 133.21 Articles bearing counterfeit trademarks....

  3. 36 CFR 7.80 - Sleeping Bear Dunes National Lakeshore.

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Sleeping Bear Dunes National Lakeshore. 7.80 Section 7.80 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.80 Sleeping Bear Dunes...

  4. Permanent magnet design for high-speed superconducting bearings

    Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

    1996-09-10

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs.

  5. Removal of radionuclides by analcime-bearing rocks

    The study of the removal of radionuclides (uranium, radium and thorium) in static conditions from aqueous solutions by analcime-bearing rocks and pure analcime was carried out. The high removal efficiency of all studied radionuclides by analcime-bearing rocks was determined. Analcime was efficient in removing of thorium only

  6. On the future of controllable fluid film bearings

    Santos, Ilmar

    2011-01-01

    This work gives an overview of the theoretical and experimental achievements of mechatronics applied to fluid film bearings. Compressible and uncompressible fluids are addressed. Rigid and elastic (deformable) bearing profiles are investigated. Hydraulic, pneumatic, magnetic and piezoelectric actuators are used. The ideas of combining control techniques, informatics with hydrodynamic, thermo-hydrodynamic, elasto-hydrodynamic and thermo-elasto-hydrodynamic lubrication techniques are carefully ...

  7. Performance of an active electric bearing for rotary micromotors

    An electric bearing used to support a micromachined rotor of variable-capacitance motors was designed and tested in order to study the characteristics of this frictionless bearing. Electrostatic suspension of a ring-shaped rotor in five degrees of freedom is required to eliminate the mechanical bearing and thus the friction and wear between the rotor and the substrate. Bulk microfabrication-based glass/silicon/glass bonding is chosen for this device, allowing the fabrication of large area sense capacitors and rotor, which make the device potentially suitable for the development of an electrostatically suspended micromachined gyroscope. The device and its basic operating principle are described, as well as the dynamics of the rotor and basic design considerations of the electric bearing system. A theoretical relationship to relate the characteristics of a classical lag–lead compensator to the stiffness properties of the electric bearing is developed to explain the experimental bearing measurements. The experimental results of closed-loop frequency response, suspension stiffness and drive voltage effects are presented and discussed for the bearing operated initially in the atmospheric environment. The performance of a tri-axial electrostatic accelerometer has also been experimentally investigated on the prototype of the electric bearing system

  8. Peculiar Aspects of Rotor-Bearing Systems Vibrations

    Radu Panaitescu-Liess

    2011-09-01

    Full Text Available The rotor-bearing systems are marked both by an asymmetrical stiffness and by important damping properties, which are causing instability in their rotating motion. The asymmetrical properties presented in this paper are displayed in the rotor motion preferential direction due to the damping internal forces mainly, and also to forces in slide bearings.

  9. How Tapered Roller Geometry Determines Bearing Energy Efficiency

    Craig Seidelson

    2011-01-01

    Full Text Available With annual global sales of approximately $5 billion [1], tapered roller bearing consumers increasingly valued energy efficient products [2]. Two of the world’s largest bearing producers, SKF [3] and Timken [4] promoted energy efficient bearings based on their abilities to grind rollers to reduced radial deviation from round (OOR. Bearing designers, however, did not know if roller geometries specified placed limitations on roller roundness. Testing under shop floor conditions at Timken, the researcher discovered a positive linear regression between roller nominal diameter and OOR. The basis for the regression was under geometric roller rounding conditions found to exist when through feed centreless grinding tapered rollers, synchronous regulating wheel vibrations transferred at higher amplitude to larger nominal diameter rollers. This research pointed energy efficient bearing design in a new direction. For example, tapered roller bearing designers typically specified rollers of minimum length to reduce problems associated with rolling contact. Bearings assembled from shorter rollers, to retain the same load capacity, required fewer rollers of larger nominal diameter. This research, however, found all things equal larger nominal diameter rollers suffered from increased OOR. Bearings designed to reduce power losses associated with rotational displacements benefited from employing more, smaller nominal diameter rollers.

  10. Human disturbances of denning polar bears in Alaska

    Amstrup, S.C. (Alaska Fish and Wildlife Research Center, Anchorage, AK (United States))

    1993-09-01

    Polar bears (Ursus maritimus) give birth in dens of snow and ice. The altricial neonates cannot leave the den for >2 months post-partum and are potentially vulnerable to disturbances near dens. The coastal plain (1002) area of Alaska's Arctic National Wildlife Refuge (ANWR) lies in a region of known polar bear denning and also may contain >9 billion barrels of recoverable oil. Polar bears in dens could be affected in many ways by hydrocarbon development. The distribution of dens on ANWR was documented between 1981 and 1992 and responses of bears in dens to various anthropogenic disturbances were observed. Of 44 dens located by radiotelemetry on the mainland coast of Alaska and Canada, 20 (45%) were on ANWR and 15 (34%) were within the 1002 area. Thus, development of ANWR will increase the potential that denning polar bears are disturbed by human activities. However, perturbations resulting from capture, marking, and radiotracking maternal bears did not affect litter sizes or stature of cubs produced. Likewise, 10 of 12 denned polar bears tolerated exposure to exceptional levels of activity. This tolerance and the fact that investment in the denning effort increases through the winter indicated that spatial and temporal restrictions on developments could prevent the potential for many disruptions of denned bears from being realized. 16 refs., 1 fig., 2 tabs.

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

    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

  12. 77 FR 5201 - Drawbridge Operation Regulation; Bear Creek, Dundalk, MD

    2012-02-02

    ... Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public meeting. But you may... SECURITY Coast Guard 33 CFR Part 117 RIN 1625-AA09 Drawbridge Operation Regulation; Bear Creek, Dundalk, MD... across Bear Creek, mile 3.4, between Dundalk and Sparrows Point, MD. The proposed change will alter...

  13. The quality of materials applied for slewing bearing raceway

    Marek Krynke

    2012-09-01

    Full Text Available Selected slewing bearings and their application have been described in this article. Basic causes of the damage pitch surfaces of slewing bearings have been analysed and examples of the damage have been presented as well. Special attention was paid to these kinds of damage which appeared most often in the case of the pitch surfaces of the bearings and those ones which very often cause premature exchange of the bearing and its scrapping. On the basis of the conducted studies it was stated that the main cause of the damage to  the pitch surfaces of the bearings is the excessive load of rolling elements. Based on the results of the conducted analysis, actions limiting the occurrence of the damage to the pitch surfaces of the bearings, which lead to their premature exchange, have been proposed. One of the suggested actions, limiting the premature exchange of bearings, is the necessity of exceptionally thorough design and selection of the slewing bearings, including the conditions of their foundation

  14. Hardening treatment of friction surfaces of ball journal bearings

    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.

  15. Human disturbances of denning polar bears in Alaska

    Polar bears (Ursus maritimus) give birth in dens of snow and ice. The altricial neonates cannot leave the den for >2 months post-partum and are potentially vulnerable to disturbances near dens. The coastal plain (1002) area of Alaska's Arctic National Wildlife Refuge (ANWR) lies in a region of known polar bear denning and also may contain >9 billion barrels of recoverable oil. Polar bears in dens could be affected in many ways by hydrocarbon development. The distribution of dens on ANWR was documented between 1981 and 1992 and responses of bears in dens to various anthropogenic disturbances were observed. Of 44 dens located by radiotelemetry on the mainland coast of Alaska and Canada, 20 (45%) were on ANWR and 15 (34%) were within the 1002 area. Thus, development of ANWR will increase the potential that denning polar bears are disturbed by human activities. However, perturbations resulting from capture, marking, and radiotracking maternal bears did not affect litter sizes or stature of cubs produced. Likewise, 10 of 12 denned polar bears tolerated exposure to exceptional levels of activity. This tolerance and the fact that investment in the denning effort increases through the winter indicated that spatial and temporal restrictions on developments could prevent the potential for many disruptions of denned bears from being realized. 16 refs., 1 fig., 2 tabs

  16. Biomechanical consequences of rapid evolution in the polar bear lineage.

    Graham J Slater

    Full Text Available The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.

  17. Lubricants for drill bit bearings and requirements for them

    Postash, S.I.; Baryl' nik, V.N.; Berko, N.Ya.; Dzugkoyev, T.D.; Postash, A.S.; Sheykin, F.I.

    1984-01-01

    Lubricants for drill bit bearings are divided by properties into lubricants for sealed (low-rotary drill bit) and unsealed (high-rotary drill bit) bearings. The operating mode of the bearings of both types of supports is heavily loaded and high-temperature; therefore, the lubricants must have high anti-wear properties and thermal resistance. Improving the reliability of the bits with sealed bearings is attained by using normal lubricants as well as special ones. Work is underway to seal the bit bearings for high-rotary drilling, but it is economically more justified to have high-rotary drilling with unsealed bearings of increased (20-30%) stability, which is achieved by using special lubricants KP, KPO, as well as hardening lubricants based on mineral oil, molybdenum disulfide and epoxy composites. In this case, the hardening lubricants which in the flowing state fill the entire cavity of the bearings not only lubricate the rocking bodies and running tracks during hardening, but also seal the cavity of the bearings and separate the rocking bodies.

  18. The Influence of Time on Bearing Capacity of Driven Piles

    Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.

    2004-01-01

    In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay, a...

  19. Acoustic analysis of an induction motor with viscoelastic bearing supports

    Tillema, H.G.; Wensing, J.A.

    2002-01-01

    The demand for silent bearing applications has resulted in the development of an effective damping layer between the outer ring of a rolling bearing and the surrounding structure. By means of numerical modeling using both FEM and BEM techniques an induction motor for household appliances is analyzed

  20. Active magnetic bearings: As applied to centrifugal pumps

    Nelik, Lev; Cooper, Paul; Jones, Graham; Galecki, Dennis; Pinckney, Frank; Kirk, Gordon

    1992-01-01

    Application of magnetic bearings to boiler feed pumps presents various attractive features, such as longer bearing life, lower maintenance costs, and improved operability through control of the rotordynamics. Magnetic bearings were fitted to an eight-stage, 600 hp boiler feed pump, which generates 2600 ft of heat at 680 gpm and 3560 rpm. In addition to the varied and severe operating environment in steady state operation of this pump in a power plant, it is also subjected to transient loads during frequent starts and stops. These loads can now be measured by the in-built instrumentation of the magnetic bearings. Following site installation, a follow-up bearing tune-up was performed, and pump transient response testing was conducted. The bearing response was completely satisfactory, ensuring trouble-free pump operation even in the range of reduced load. The experience gained so far through design and testing proves feasibility of magnetic bearings for boiler feed pumps, which sets the stage for application of even higher energy centrifugal pumps equipped with magnetic bearings.

  1. Grizzly bear nutrition and ecology studies in Yellowstone National Park

    Robbins, Charles T.; Schwartz, Charles C.; Gunther, Kerry A.; Servheen, Christopher

    2006-01-01

    T HE CHANCE TO SEE a wild grizzly bear is often the first or second reason people give for visiting Yellow - stone National Park. Public interest in bears is closely coupled with a desire to perpetuate this wild symbol of the American West. Grizzly bears have long been described as a wilderness species requiring large tracts of undisturbed habitat. However, in today’s world, most grizzly bears live in close proximity to humans (Schwartz et al. 2003). Even in Yellowstone National Park, the impacts of humans can affect the long-term survival of bears (Gunther et al. 2002). As a consequence, the park has long supported grizzly bear research in an effort to understand these impacts. Most people are familiar with what happened when the park and the State of Montana closed open-pit garbage dumps in the late 1960s and early 1970s, when at least 229 bears died as a direct result of conflict with humans. However, many may not be as familiar with the ongoing changes in the park’s plant and animal communities that have the potential to further alter the park’s ability to support grizzly bears.

  2. Development of reversible strain gage

    A high-temperature strain gage which can be peeled after taking required apparent strain measurements in a furnace and can be attached reverse-side-up at the point of interest on a test structure was developed. Using the ''reversible'' strain gage with selected room-temperature curing type polyester adhesive, one can expect to measure thermal strain accurately, especially for on large structures, at the first test in temperature up to 250 deg C. The repeatability of apparent strains for about 100 reversible gages was within 50 microstrains of difference at 250 deg C (within 30 microstrains of difference for 80 % of the test gages). (author)

  3. Nonlinear dynamic behaviors of ball bearing rotor system

    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.

  4. Novel parameter-based flexure bearing design method

    Amoedo, Simon; Thebaud, Edouard; Gschwendtner, Michael; White, David

    2016-06-01

    A parameter study was carried out on the design variables of a flexure bearing to be used in a Stirling engine with a fixed axial displacement and a fixed outer diameter. A design method was developed in order to assist identification of the optimum bearing configuration. This was achieved through a parameter study of the bearing carried out with ANSYS®. The parameters varied were the number and the width of the arms, the thickness of the bearing, the eccentricity, the size of the starting and ending holes, and the turn angle of the spiral. Comparison was made between the different designs in terms of axial and radial stiffness, the natural frequency, and the maximum induced stresses. Moreover, the Finite Element Analysis (FEA) was compared to theoretical results for a given design. The results led to a graphical design method which assists the selection of flexure bearing geometrical parameters based on pre-determined geometric and material constraints.

  5. Friction and Lubrication of Large Tilting-Pad Thrust Bearings

    Michał Wasilczuk

    2015-04-01

    Full Text Available Fluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due to viscous shearing of the lubricant large tilting pad thrust bearings, and this requires systems for forced cooling of the lubricant. In the dominant bath lubrication systems, cooling is realized by internal coolers or external cooling systems, with the latter showing some important advantages at the cost of complexity and also, potentially, lower reliability. Substantial losses in the bearings, reaching 1 MW in extreme cases, are a good motivation for the research and development aimed at reducing them. Some possible methods and their potential efficiency, along with some effects already documented, are also described in the paper.

  6. Research on Service Life Prediction Model of Thrust Needle Bearing

    Li Wei

    2012-11-01

    Full Text Available Needle roller thrust bear is small in size and of high ability in load bearing, therefore it is widely used in fields of aviation and automobile etc.  But the relation between their service life and pre-tightening torque is not very clear, so the using design of the bear depends mainly on experience of engineer, because of lack of references. In the paper, the theoretical analysis on relation between torque and load is done, special wearing test instrument is developed and wearing test of thrust needle bear is conducted. Based on the results of the test, mathematical model of relation between the losing amount of pre-tightening torque and the pre-tightening torque is built, based on which use of the bear in engineering will be more reasonable, and their pre-tightening torque will be given more accurately.

  7. Modeling of dynamically loaded hydrodynamic bearings at low Sommerfeld numbers

    Thomsen, Kim

    hydrodynamic performance and related phenomena: • a new wear model is proposed which can, with only moderate efforts, be implemented into existing EHD models. • it is discovered that radial tilting pad bearings can exhibit discontinuity effects when subjected high dynamic loads. • the influence of compliant...... liners on the dynamic response of journal bearings subjected to dynamic loads is studied using a soft EHD model. • the influence of the geometrical design parameters of a radial flexure pad is studied as well as the effect of a compliant liner using an EHD model. • an innovative radial flexure journal......Current state of the art within the wind industry dictates the use of conventional rolling element bearings for main bearings. As wind turbine generators increase in size and output, so does the size of the main bearings and accordingly also the cost and potential risk of failure modes. The cost...

  8. Dynamics of High-Speed Rotors Supported in Sliding Bearings

    Šimek, J.; Svoboda, R.

    The higher the operating speed, the more serious are problems with rotor stability. Three basic groups of rotors are analyzed and some methods of suppressing instability are shown. In the first group are classical elastic rotors supported in hydrodynamic bearings. Practically all high-speed rotors now run in tilting pad bearings, which are inherently stable, but in specific conditions even tiling pad bearings may not ensure rotor stability. The second group is composed of combustion engines turbocharger rotors, which are characteristic by heavy impellers at both overhung ends of elastic shaft. These rotors are in most cases supported in floating ring bearings, which bring special features to rotor behaviour. The third group of rotors with gas bearings exhibits special features.

  9. Experimental evaluation of mechanical property for FPS isolation bearings

    The FPS isolation bearings produce the isolation effect by introducing flexibility and energy absorption capability at an interface between the structure and the moving ground. In this system, the structure on FPS bearing behaves as a pendulum of length R, where R is the radius of curvature of the spherical sliding surface. There are two important advantages in friction pendulum systems; The bearings have high vertical load capacity and stability. The properties of flexibility, energy absorption capability and vertical load capacity are not interrelated. In this study, A series of laboratory experiments has been conducted to determine the effect of sliding velocity, bearing pressure, test waveform, and horizontal displacement on the frictional characteristics of FPS isolation bearings. As a result, it is found that frictional coefficient increases with increasing velocity up to a certain value and frictional coefficient drops with increasing pressure

  10. The application of dichotomy in equilibrium position of journal bearing

    Wu, G. K.; Luo, X. Q.

    2016-05-01

    The fluid lubricant force in the journal bearing is an important factor for the stability and dynamic characteristics of rotating machine. In order to obtain the dynamic coefficients of journal bearing, the equilibrium position must be known for further calculation. In this paper, the Reynolds equation is solved by finite difference method and the dichotomy is applied to acquire the equilibrium position of journal bearing by means of double loop. The effects of length, radius and clearance of journal bearing on the equilibrium position are also researched. The calculated results show that the dichotomy is an effective method for the equilibrium position of journal bearing and the geometry parameters play an important effect on the equilibrium position.

  11. On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

    Morosi, Stefano; Santos, Ilmar

    2010-01-01

    compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... conventional oil bearings, carrying capacity and dynamic characteristics of passive systems are generally poorer. In order to enhance these characteristics, one solution is to employ active control strategies. The present contribution presents a detailed mathematical modeling for active lubrication of a...

  12. Plain bearing stresses due to forming and oil film pressure

    Burke-Veliz, A.; Wang, D.; Wahdy, N.; Reed, P. A. S.; Merritt, D.; Syngellakis, S.

    2009-08-01

    This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

  13. Understanding the bear movement in gay male culture: redefining masculinity.

    Manley, Eric; Levitt, Heidi; Mosher, Chad

    2007-01-01

    The bear movement emerged in the gay male culture of the 1980s, but little research on this group has been conducted. The purpose of this qualitative study was to examine the meanings and functions of bear identity. Six bear-identified men participated in intensive interviews investigating this question. Results suggest that men who identify as bears consciously adopt a masculine aesthetic that signifies values of self-acceptance and maturity. The participants described the acceptance of diverse body shapes and ages within the bear community as leading to positive self-esteem and body image. Results are discussed in relation to clinical and advocacy work. They broaden the awareness of the diversity of cultures that exist within the gay community. PMID:18689193

  14. Diagnosis of bearing creep in wind turbine gearboxes

    Skrimpas, Georgios Alexandros; Liu, Zhenyan; Hilmisson, Reynir;

    2016-01-01

    bearings where their outer races are fixed to the gearbox and their inner races rotate at the corresponding shaft speed. Bearing inner race defects are frequently encountered in gearboxes leading to either replacement of the whole unit or exchange of the shaft or bearing where feasible. The present work...... deals with the evaluation of the development of an inner race defect from surface pitting to race axial crack resulting in excessive rotational looseness, also referred to as bearing creep. It is shown that an inner race defect can be identified efficiently at an early stage by employing well known...... vibration condition indicators, e.g. crest factor, whereas development to rotational looseness is expressed as increased sideband activity between the gear mesh frequencies spaced at the shaft speed supported by the defective bearing due to abnormal meshing. The condition of the gears and the shaft during...

  15. An Advanced Microturbine System with Water-Lubricated Bearings

    Susumu Nakano

    2009-01-01

    Full Text Available A prototype of the next-generation, high-performance microturbine system was developed for laboratory evaluation. Its unique feature is its utilization of water. Water is the lubricant for the bearings in this first reported application of water-lubricated bearings in gas turbines. Bearing losses and limitations under usage conditions were found from component tests done on the bearings and load tests done on the prototype microturbine. The rotor system using the water-lubricated bearings achieved stable rotating conditions at a rated rotational speed of 51,000 rpm. An electrical output of 135 kW with an efficiency of more than 33% was obtained. Water was also utilized to improve electrical output and efficiency through water atomizing inlet air cooling (WAC and a humid air turbine (HAT. The operation test results for the WAC and HAT revealed the WAC and HAT operations had significant effects on both electrical output and electrical efficiency.

  16. Auxiliary bearing design considerations for gas cooled reactors

    The need to avoid contamination of the primary system, along with other perceived advantages, has led to the selection of electromagnetic bearings (EMBs) in most ongoing commercial-scale gas cooled reactor (GCR) designs. However, one implication of magnetic bearings is the requirement to provide backup support to mitigate the effects of failures or overload conditions. The demands on these auxiliary or 'catcher' bearings have been substantially escalated by the recent development of direct Brayton cycle GCR concepts. Conversely, there has been only limited directed research in the area of auxiliary bearings, particularly for vertically oriented turbomachines. This paper explores the current state-of-the-art for auxiliary bearings and the implications for current GCR designs. (author)

  17. Characteristics of Electrorheological Fluid Flow in Journal Bearings

    张准; 朱克勤

    2002-01-01

    Under the influence of an applied electric field, the variation of apparent viscosity of electrorheological (ER) fluid flow causes ER effects. According to the Bingham model, which is widely used for describing the rheological properties of ER fluids, this variation should be very weak at high shear rates. To clarify the ER effects in ER journal bearings at high shear rate, a numerical study is presented. It is found that under the influence of the applied electric field, ER effects in ER journal bearings can be affected by not only the apparent viscosity of ER fluids but also the movement of yield surface in the clearance of ER journal bearing. In the case of low shear rate, both are effective on the lubricant film pressure of ER journal bearings. In the case of high shear rates, the main factor is the extension of non-yield region in the bearing clearance.

  18. Experimental Grey Box Model Identification of an Active Gas Bearing

    Theisen, Lukas Roy Svane; Pierart Vásquez, Fabián Gonzalo; Niemann, Hans Henrik;

    2014-01-01

    Gas bearings have inherent dynamics that gives rise to low damping and potential instability at certain rotational speeds. Required damping and stabilization properties can be achieved by active ow control if bearing parameters are known. This paper deals with identifacation of parameters in a...... dynamic model of an active gas bearing and subsequent control loop design. A grey box model is determined based on experiments where piezo actuated valves are used to perturb the journal and hence excite the rotor-bearing system. Such modelling from actuator to output is shown to effciently support...... controller design, in contrast to impact models that focus on resonance dynamics. The identified model is able to accurately reproduce the lateral dynamics of the rotor-bearing system in a desired operating range, in this case around the first two natural frequencies. The identified models are validated and...

  19. Nonlinear Analyses of the Dynamic Properties of Hydrostatic Bearing Systems

    LIU Wei(刘伟); WU Xiujiang(吴秀江); V.A. Prokopenko

    2003-01-01

    Nonlinear analyses of hydrostatic bearing systems are necessary to adequately model the fluid-solid interaction. The dynamic properties of linear and nonlinear analytical models of hydrostatic bearings are compared in this paper. The analyses were based on the determination of the aperiodic border of transient processes with external step loads. The results show that the dynamic properties can be most effectively improved by increasing the hydrostatic bearing crosspiece width and additional pocket volume in a bearing can extend the load range for which the transient process is aperiodic, but an additional restrictor and capacitor (RC) chain must be introduced for increasing damping. The nonlinear analyses can also be used to predict typical design parameters for a hydrostatic bearing.

  20. Structural Reliability of Plain Bearings for Wave Energy Converter Applications

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2016-01-01

    critical structural components, like welded details, bolts or bearings. This paper considers reliability studies with a focus on plain bearings available from stock for the Wavestar device, which exists at the prototype level. The Wavestar device is a point absorber WEC. The plan is to mount a new power...... of the different available plain bearings planned to be mounted at the new PTO system based on a probabilistic approach, and the paper gives suggestions for fulfilling the minimal target reliability levels. The considered failure mode in this paper is the brittle fatigue failure of plain bearings....... The performed sensitivity analysis shows that parameters defining the initial crack size have a big impact on the resulting reliability of the plain bearing....