Sample records for tube-in-tube slip joint

  1. Leakage flow-induced vibration of an eccentric tube-in-tube slip joint

    SciTech Connect

    Mulcahy, T.M.

    1985-08-01

    Eccentricity of a specific slip-joint design separating two cantilevered, telescoping tubes did not create any self-excited lateral vibrations that had not been observed previously for a concentric slip joint. In fact, the eccentricity made instabilities less likely to occur, but only marginally. Most important, design rules previously established to avoid instabilities for the concentric slip joint remain valid for the eccentric slip joint. 6 refs., 9 figs., 2 tabs.

  2. Leakage flow-induced vibration of an unconstricted tube-in-tube slip joint

    SciTech Connect

    Mulcahy, T.M.

    1986-12-01

    The conditions are given for which the more flexible of two cantilevered, telescoping tubes conveying fluid can be self-excited by flow leaking from an unconstricted slip joint. Also, a physical explanation of the excitation mechanism is discussed, and a design rule to avoid the mechanism is presented. In addition, the results for the unconstricted slip joint are shown to be similar to those for slip joints having annulus constrictions at very short engagement lengths.

  3. Leakage flow-induced vibrations for variations of a tube-in-tube slip joint

    SciTech Connect

    Mulcahy, T.M.

    1986-01-01

    Variations in the design of a specific slip joint separating two cantilevered, telescoping tubes conveying water were studied to determine their effect upon the leakage flow-induced vibration self-excitation mechanism known to exist for the original slip joint geometry. The important parameters controlling the self-excitation mechanism were identified, which, along with previous results, allowed the determination of a comprehensive set of design rules to avoid unstable vibrations. This was possible even though a new self-excitation mechanism was found when the engagement of the two tubes was small. 9 refs.

  4. Avoiding leakage flow-induced vibration by a tube-in-tube slip joint

    SciTech Connect

    Mulcahy, T.M.

    1984-10-01

    Parameters and operating conditions (a stability map) were determined for which a specific slip-joint design did not cause self-excited lateral vibration of the two cantilevered, telescoping tubes forming the joint. The joint design featured a localized annular constriction. Flowrate, modal damping, tube engagement length, and eccentric positioning were among the parameters tested. Interestingly, all self-excited vibrations could be avoided by following a simple design rule: place constrictions only at the downstream end of the annular region between the tubes. Also, overall modal damping decreased with increased flowrate, at least initially, for upstream constrictions while the damping increased for downstream constrictions.

  5. Assembly of carbon tube-in-tube nanostructures

    Microsoft Academic Search

    D. S. Su; Z. P. Zhu; X. Liu; G. Weinberg; N. Wang; R. Schlögl

    2005-01-01

    Tube-in-tube carbon nanostructures were prepared by reorganization of graphitic impurity nanoparticles outside or inside of the pristine carbon nanotubes. Graphitic impurity nanoparticles were first disintegrated into small graphene fragments by a chemical oxidation with nitric acid, which also modifies the graphene fragments with carboxyl and hydroxyl groups at their edges. The functionalized graphene fragments were then reintegrated outside or inside

  6. Assembly of carbon tube-in-tube nanostructures

    NASA Astrophysics Data System (ADS)

    Su, D. S.; Zhu, Z. P.; Liu, X.; Weinberg, G.; Wang, N.; Schlögl, R.

    2005-09-01

    Tube-in-tube carbon nanostructures were prepared by reorganization of graphitic impurity nanoparticles outside or inside of the pristine carbon nanotubes. Graphitic impurity nanoparticles were first disintegrated into small graphene fragments by a chemical oxidation with nitric acid, which also modifies the graphene fragments with carboxyl and hydroxyl groups at their edges. The functionalized graphene fragments were then reintegrated outside or inside of pristine carbon nanotubes to construct into tube-in-tube nanostructures. The combination of oxidatively functionalized graphene units, their solvate in a polar organic medium allowing for dispersive forces to effect supramolecular organization with carbon nanotubes acting as templates and their polycondensation by acid-catalysed esterification followed by pyrolysis of the oxygen functionalities lead to complex nanostructures inaccessible by direct synthesis.

  7. Mass Transport and Reactions in the Tube-in-Tube Reactor

    E-print Network

    Yang, Lu

    The tube-in-tube reactor is a convenient method for implementing gas/liquid reactions on the microscale, in which pressurized gas permeates through a Teflon AF-2400 membrane and reacts with substrates in liquid phase. Here ...

  8. Performance of multi tubes in tube helically coiled as a compact heat exchanger

    NASA Astrophysics Data System (ADS)

    Nada, S. A.; El Shaer, W. G.; Huzayyin, A. S.

    2014-12-01

    Multi tubes in tube helically coiled heat exchanger is proposed as a compact heat exchanger. Effects of heat exchanger geometric parameters and fluid flow parameters; namely number of inner tubes, annulus hydraulic diameter, Reynolds numbers and input heat flux, on performance of the heat exchanger are experimentally investigated. Different coils with different numbers of inner tubes, namely 1, 3, 4 and 5 tubes, were tested. Results showed that coils with 3 inner tubes have higher values of heat transfer coefficient and compactness parameter (bar{h} Ah ). Pressure drop increases with increasing both of Reynolds number and number of inner tubes. Correlations of average Nusselt number were deduced from experimental data in terms of Reynolds number, Prandtl number, Number of inner coils tubes and coil hydraulic diameter. Correlations prediction was compared with experimental data and the comparison was fair enough.

  9. Investigation of Turn-of-Nut Method for Slip-Critical Joints of Aluminum Using A325 Bolts

    SciTech Connect

    Luttrell, C R [ORNL

    1998-01-01

    Slip-critical bolted joints will be used to join aluminum bridge deck sections by Reynolds Metals Company (RMC). To help ensure that a joint does not slip the proper bolt clamping force to achieve what is known as a friction connection must be determined.

  10. Flow chemistry: intelligent processing of gas-liquid transformations using a tube-in-tube reactor.

    PubMed

    Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

    2015-02-17

    CONSPECTUS: The previous decade has witnessed the expeditious uptake of flow chemistry techniques in modern synthesis laboratories, and flow-based chemistry is poised to significantly impact our approach to chemical preparation. The advantages of moving from classical batch synthesis to flow mode, in order to address the limitations of traditional approaches, particularly within the context of organic synthesis are now well established. Flow chemistry methodology has led to measurable improvements in safety and reduced energy consumption and has enabled the expansion of available reaction conditions. Contributions from our own laboratories have focused on the establishment of flow chemistry methods to address challenges associated with the assembly of complex targets through the development of multistep methods employing supported reagents and in-line monitoring of reaction intermediates to ensure the delivery of high quality target compounds. Recently, flow chemistry approaches have addressed the challenges associated with reactions utilizing reactive gases in classical batch synthesis. The small volumes of microreactors ameliorate the hazards of high-pressure gas reactions and enable improved mixing with the liquid phase. Established strategies for gas-liquid reactions in flow have relied on plug-flow (or segmented flow) regimes in which the gas plugs are introduced to a liquid stream and dissolution of gas relies on interfacial contact of the gas bubble with the liquid phase. This approach confers limited control over gas concentration within the liquid phase and is unsuitable for multistep methods requiring heterogeneous catalysis or solid supported reagents. We have identified the use of a gas-permeable fluoropolymer, Teflon AF-2400, as a simple method of achieving efficient gas-liquid contact to afford homogeneous solutions of reactive gases in flow. The membrane permits the transport of a wide range of gases with significant control of the stoichiometry of reactive gas in a given reaction mixture. We have developed a tube-in-tube reactor device consisting of a pair of concentric capillaries in which pressurized gas permeates through an inner Teflon AF-2400 tube and reacts with dissolved substrate within a liquid phase that flows within a second gas impermeable tube. This Account examines our efforts toward the development of a simple, unified methodology for the processing of gaseous reagents in flow by way of development of a tube-in-tube reactor device and applications to key C-C, C-N, and C-O bond forming and hydrogenation reactions. We further describe the application to multistep reactions using solid-supported reagents and extend the technology to processes utilizing multiple gas reagents. A key feature of our work is the development of computer-aided imaging techniques to allow automated in-line monitoring of gas concentration and stoichiometry in real time. We anticipate that this Account will illustrate the convenience and benefits of membrane tube-in-tube reactor technology to improve and concomitantly broaden the scope of gas/liquid/solid reactions in organic synthesis. PMID:25611216

  11. Age-related joint moment characteristics during normal gait and successful reactive-recovery from unexpected slip perturbations.

    PubMed

    Liu, Jian; Lockhart, Thurmon E

    2009-10-01

    The objective of the current study was to investigate the effects of aging on 3D lower extremity joint moments during successful reactive-recovery from unexpected slips. Unexpected slips were induced by having participants walk over a slippery floor surface. Successful reactive-recovery trials from nine young and nine elderly participants were identified and analyzed. Three-dimensional inverse dynamics were implemented to calculate reactive joint moments at the ankle, knee, and hip joints. Peak joint moment magnitude and the speed of peak joint moment generation were used to describe the balance recovery strategies from unexpected slips. Results indicated significantly higher peak joint moments in recovery than in normal walking for both the young and elderly. Meanwhile, during reactive-recovery, the elderly were found to utilize both frontal and sagittal joint moments while the younger adults relied primarily on sagittal joint moment. It was concluded that the ankle and knee joints were critical in controlling sagittal plane motion disturbance, while the hip joint was mainly responsible for stabilizing upper body balance in the frontal plane. This study confirmed age-related differences in joint moment generation during unexpected slips. Additionally, implementing 3D analysis is recommended in future slips and falls research. PMID:19581088

  12. Age-related joint moment characteristics during normal gait and successful reactive-recovery from unexpected slip perturbations

    Microsoft Academic Search

    Jian Liu; Thurmon E. Lockhart

    2009-01-01

    The objective of the current study was to investigate the effects of aging on 3D lower extremity joint moments during successful reactive-recovery from unexpected slips. Unexpected slips were induced by having participants walk over a slippery floor surface. Successful reactive-recovery trials from nine young and nine elderly participants were identified and analyzed. Three-dimensional inverse dynamics were implemented to calculate reactive

  13. Deep coseismic slip of the 2008 Wenchuan earthquake inferred from joint inversion of fault stress changes and GPS surface displacements

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Yang, Yinghui; Luo, Rong; Liu, Guoxiang; Zhang, Kui

    2015-07-01

    Geodetic data are increasingly being used to infer coseismic slip distribution due to its advantages of wide coverage and high accuracy. However, it is difficult to obtain a comprehensive rupture pattern at depth when a source model is only constrained by geodetic surface deformation. In this study, a joint inversion approach incorporating stress changes and GPS surface displacements is explored and applied to characterize the fault slip of the 2008 Mw 7.9 Wenchuan earthquake, China. The earthquake data for the 20-year period before the main quake, which are collected from the background seismicity catalogues, and one month of aftershock data are statistically analysed to determine the fault stress changes based on the Dieterich model. The coseismic surface deformation measurements from 158 GPS surveying sites are jointly used to constrain the solution. Our preferred rupture model reveals four high-slip concentrations on the Yingxiu-Beichuan fault and one on the subparallel PengGuan fault. The spatial distribution suggests that the coseismic slip occurs not only above the hypocentre but also with a significant thrusting motion, with a mean slip of 8.5 m and a maximum of 9.7 m at a depth of 10-16 km. A significant high-slip concentration is found for the first time in this study. The coseismic faulting extends toward ?16 km southwest of the Yingxiu-Beichuan fault and has a dextral strike-slip with a mean displacement of 4.8 m at a depth of 7-19 km. The joint inversion model misfits (GPS: 1.7 cm, stress change: 0.02 MPa) exhibit a good compatibility between the two types of datasets. The derived slip model, which has an improved resolution at depth, explains 98% of the coseismic surface displacements and 93% of the fault stress changes.

  14. In situ modifying of carbon tube-in-tube nanostructures with highly active Fe(2)O(3) nanoparticles.

    PubMed

    Bai, Shuli; Zhao, Jianghong; Du, Guixiang; Zheng, Jianfeng; Zhu, Zhenping

    2008-05-21

    A novel in situ method based on a liquid membrane templated self-assembly process is employed to modify carbon tube-in-tube nanostructures (TTCNTs) with Fe(2)O(3) nanoparticles. The as-obtained Fe(2)O(3) modified TTCNTs (Fe(2)O(3)/TTCNTs) nanocomposites are well constructed and the Fe(2)O(3) nanoparticles are well dispersed and decorated on the outer, inner and intramolecular surfaces of TTCNTs. In addition, the Fe(2)O(3)/TTCNTs nanocomposites are employed as catalysts for selective catalytic reduction (SCR) of NO with NH(3) and show high SCR catalytic activity, indicating that the novel multiple intramolecular channels and unique surface chemistry of the TTCNTs should play an important role in improving the properties of TTCNTs. PMID:21825743

  15. Resin injected bolted connections: A step towards achieving slip-resistant joints in FRP

    E-print Network

    Mottram, Toby

    of resin ­ slip not more than 0 150.15 mm. 2. Static creep test · Test for determination of design bearing t t bli h 4 · Bearing resistance from creep test is used to establish bearing stress ranges. · If total slip between the inner and outer plates is more than 0.3 mm, the fatigue life is at its end. #12

  16. Symphysis pubis width and unaffected hip joint width in patients with slipped upper femoral epiphysis: widening compared with normal values

    Microsoft Academic Search

    Bernhard Tins; Victor Cassar-Pullicino; Mike Haddaway

    2010-01-01

    Background  The exact pathomechanism of slipped upper femoral epiphysis (SUFE) remains elusive. This paper suggests a generalised abnormality\\u000a of the development or maturation of cartilage as a possible cause.\\u000a \\u000a \\u000a \\u000a \\u000a Objective  It is proposed that SUFE is part of a generalised abnormality of the cartilage formation or maturation resulting in abnormal\\u000a measurements of cartilaginous joint structures.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Radiographs of SUFE patients were

  17. Growth, linkage, and termination processes of a 10-km-long strike-slip fault in jointed granite: the Gemini fault zone, Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Pachell, Matthew A.; Evans, James P.

    2002-12-01

    Field-based structural analysis of an exhumed, ˜10-km-long strike-slip fault zone elucidates processes of growth, linkage, and termination along moderately sized strike-slip fault zones in granitic rocks. The Gemini fault zone is a 9.3-km-long, left-lateral fault system that was active at depths of 8-11 km within the transpressive Late-Cretaceous Sierran magmatic arc. The fault zone cuts four granitic plutons and is composed of three steeply dipping northeast- and southwest-striking noncoplanar segments that nucleated and grew along preexisting cooling joints. The fault core is bounded by subparallel fault planes that separate highly fractured epidote-, chlorite-, and quartz-breccias from undeformed protolith. The slip profile along the Gemini fault zone shows that the fault zone consists of three 2-3-km-long segments separated by two 'zones' of local slip minima. Slip is highest (131 m) on the western third of the fault zone and tapers to zero at the eastern termination. Slip vectors plunge shallowly west-southwest and show significant variability along strike and across segment boundaries. Four types of microstructures reflect compositional changes in protolith along strike and show that deformation was concentrated on narrow slip surfaces at, or below, greenschist facies conditions. Taken together, we interpret the fault zone to be a segmented, linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and fault rock resulted in nonuniform slip orientations, complex fault-segment interactions, and asymmetric slip-distance profiles.

  18. Synthesis and characterization of a novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite for supercapacitor

    SciTech Connect

    Li, Juan, E-mail: lj-panpan@163.com [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Que, Tingli [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China)] [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Huang, Jianbin, E-mail: JBhuang@pku.edu.cn [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2013-02-15

    Graphical abstract: A novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite have been successfully fabricated. Its inner tubules are CNTs and the outer tubules are template-synthesized PPy. Most MnO{sub 2} nanoparticles are sandwiched between the inner and outer wall, some relatively large particles are also latched onto the outside wall of the PPy tube. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test and galvanostatic charge–discharge experiments at different current densities. Display Omitted Highlights: ? We fabricate a ternary organic–inorganic complex of PPy/MnO{sub 2}/CNTs composite. ? We characterize its morphological structures and properties by several techniques. ? The composite possesses the typical tube-in-tube nanostructures. ? Most MnO{sub 2} nanoparticles are sandwiched between the inner CNTs and outer PPy wall. ? The composite has good electrochemical reversibility for supercapacitor. -- Abstract: Ternary organic–inorganic complex of polypyrrole/manganese dioxide/carbon nanotubes (PPy/MnO{sub 2}/CNTs) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO{sub 2} and CNTs, using complex of methyl orange (MO)/FeCl{sub 3} was used as a reactive self-degraded soft-template. The morphological structures of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopic (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively. All the results indicate that the PPy/MnO{sub 2}/CNTs composite possesses the typical tube-in-tube nanostructures: the inner tubules are CNTs and the outer tubules are template-synthesized PPy. MnO{sub 2} nanoparticles may either sandwich the space between the inner and outer tubules or directly latch onto the wall of the PPy tubes. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test in the potential range of ?0.6 to 0.4 V and its specific capacitance was up to 402.7 F g{sup ?1} at a current density of 1 A g{sup ?1} in galvanostatic charge–discharge experiment.

  19. Experimental investigation of the dynamic installation of a slip joint connection between the monopile and tower of an offshore wind turbine

    NASA Astrophysics Data System (ADS)

    Segeren, M. L. A.; Hermans, K. W.

    2014-06-01

    The failure of the traditional grouted connections of offshore wind turbines has led to the investigation of alternatives that provide a connection between the foundation pile and the turbine tower. An alternative to the traditional joint is a steel-to-steel connection also called a slip joint. To ensure a proper fit of the slip joint a dynamic installation of the joint is proposed. In this contribution, the effectiveness of harmonic excitation as an installation procedure is experimentally investigated using a 1:10 scaled model of the joint. During the dynamic installation test the applied static load, settlements and dynamic response of the joint are monitored using respectively load cells, taut wires and strain gauges placed both inside and outside the conical surfaces. The results show that settlement occurs only when applying a harmonic load at specific forcing frequencies. The settlement stabilizes to a certain level for each of the specific frequencies, indicating that a controlled way of installation is possible. The results show that it is essential to vibrate at specific frequencies and that a larger amplitude of the harmonic force does not automatically lead to additional settlement.

  20. Coseismic Fault Slip Rupture from the Joint Inversion of Teleseismic, Local Strong-Motion and CGPS Related to the 2010 Jia-Shian Earthquake in Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Kuan-Chuan; Delouis, Bertrand; Hu, Jyr-Ching; Nocquet, Jean-Mathieu; Mozziconacci, Laetitia; Bethoux, Nicole

    2013-04-01

    The Jia-Shian earthquake (Mw=6.3) occurred on 04th March 2010 in the southwestern Taiwan. We used the waveforms of teleseismics to identify the strike, dip and rake of focal mechanism are 311/33/37. Furthermore, we explored the strike, dip and rake are 316/40/44 on the first pulse of the teleseismic P wave. We also took account of the Continuous Global Positioning System (CGPS) data for the coseismic offset. The maximum horizontal and vertical (uplift) of coseismic offsets at the surface are 29.8mm± 1.0mm and 30.6mm± 5.1mm, respectively at station GS51. Moreover, the space and time distribution of slip during the coseismic rupture was modeled by the joint inversion, which includes the CGPS coseismic offset, the teleseismic, and near field seismic records. We identified the faults geometry and reconstructed the rupture process of coseismic faults slip. The initial rupture was generated on the northwest - southeast trending fault and propagated to the northeast - southwest trending structure after 5 s of main shock. Their strike, dip and rake are 311/33/37 and 020/25/108, respectively. The average slip of rupture was 20.1 cm, with the maximum slip of 50.4 cm. The rupture of the seismic moment was 4.0 × 10 ^ 25 dyne-cm in 30 s of duration time.The slip rupture constrained the synthetic data quite well, especially for the CGPS coseismic offset. We inferred the Jia-Shian earthquake took place on blind fault and the northeast - southwest trending structure was activated following the rupture on main northwest - southeast trending fault.

  1. Localized Fault Slip to the Trench in the 2010 Maule, Chile M­w = 8.8 Earthquake from Joint Inversion of High-Rate GPS, Teleseismic Body Waves, InSAR, and Tsunami Observations

    NASA Astrophysics Data System (ADS)

    Yue, H.; Lay, T.; Rivera, L. A.; An, C.; Vigny, C.; Tong, X.

    2014-12-01

    The 27 February 2010, Mw 8.8 Maule earthquake ruptured ~500 km along the plate boundary offshore of central Chile between 34°S and 38.5°S. Intense ground shaking and large tsunami inundation combined to take more than 500 lives. The co-seismic slip distribution has previously been investigated using geodetic, seismic and tsunami observations, yielding consistent locations of the largest slip in a region extending from 34°S to 35.5°S. However, it remains uncertain whether co-seismic fault offset extended to the trench, which is important for interpreting both shallow frictional behavior and potential for tsunami earthquakes in the region. Joint inversion of high-rate GPS, teleseismic body waves, InSAR, and tsunami observations yields a kinematic rupture model with improved resolution of slip near the trench. Two up-dip large-slip (>15 m) patches are resolved along a bi-lateral rupture with relatively uniform 5-10 m slip down-dip beneath the coast. Both up-dip patches have significant slip in localized regions extending to the trench. The peak slip is ~22 m at a depth of ~15 km on the central megathrust, located ~200 km north from the hypocenter and overlapping the rupture zone of the 1928 M ~8 event. The slip decreases at shallower depth, but is still about ~20 m near the trench. The peak slip is ~15 m in a shallow near-trench patch located ~150 km southwest of the hypocenter. Checker-board resolution tests demonstrate that the tsunami data are critical to resolution of slip near the trench, with other data sets allowing, but not requiring slip far offshore. The stability of the joint inversion reduces the need for regularization. Larger events in the aftershock sequence have a complementary distribution to the co-seismic slip pattern, filling in gaps or outlining edges of large-slip zones. Two clusters of normal faulting events locate seaward along the plate motion direction from the localized regions of large near-trench slip, suggesting that proximity of slip to the trench enhanced extensional faulting in the underthrusting plate.

  2. Lower extremity corrective reactions to slip events

    Microsoft Academic Search

    Rakié Cham; Mark S Redfern

    2001-01-01

    A significant number of injuries in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether the outcome of a slip will be recovery or a fall. The goal of this study was to examine lower extremity joint moments and postural adjustments for experimental evidence of corrective strategies evoked during slipping in an attempt

  3. Depth distribution of coseismic slip along the Nankai Trough, Japan, from joint inversion of geodetic and tsunami data

    Microsoft Academic Search

    Kenji Satake

    1993-01-01

    Two large earthquakes, the 1944 Tonankai earthquake and the 1946 Nankaido earthquake, occurred on the Nankai trough, where the Philippine Sea plate is subducting beneath the Eurasian plate. Coseismic crustal movements on land were measured by leveling, while those in ocean were recorded as tsunami waveforms on tide gauges. The coseismic slip distribution inverted from these data shows that the

  4. Spatiotemporal model of aseismic slip on the Hayward fault inferred from joint inversion of geodetic and seismic data time series

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Burgmann, R.

    2011-12-01

    Interferometric synthetic aperture radar (InSAR) provides valuable spatiotemporal observations of surface deformation in volcanic and tectonic areas. In this study we generate a long time series of InSAR-measured deformation over the San Francisco Bay Area by combining over 100 ERS1/2 and Envisat SAR acquisitions from 1992 through 2011. We apply an advanced multitemporal processing algorithm that uses multiple-master interferometry and generate about 700 interferograms (ERS-ERS, Envisat-Envisat and ERS-Envisat pairs) with temporal and perpendicular baseline smaller than 4 years and 300 m, respectively. The systematic errors (such as DEM error and atmospheric delay) are estimated and reduced by using a variety of wavelet based filters. The differential displacement measured in each unwrapped interferogram is inverted by using an L1-norm minimization approach to generate time series of the surface displacement for identified stable pixels. Using a Kalman filter, the line-of-sight velocity is estimated, temporal random noise is reduced and the displacement variance-covariance matrix is refined. To solve for the time dependent model of aseismic slip on the Hayward fault, the upper-crustal fault plane is discretized into triangular patches. The size of these patches is optimized in a way that allows estimating the fault slip with maximum precision. Then, we apply an iterated inversion approach, combining static slip inversion and Kalman filtering to model temporal behavior of the slip. For the static inversion we expand the slip to the wavelet base functions and truncate noisy coefficients, which provide a solution equivalent to implementation of the Laplace smoothing operator in conventional slip inversion. This novel approach, however, overcomes the need of choosing a smoothing operator and allows automating the whole inversion step. Since we aim to integrate seismic and creepmeter data sets, the issue of relative weighting of these data sets becomes important, which we address by applying a new statistical method. This method incorporates an iterative algorithm that statistically estimates the true relative weight of different observations. Combination of the advanced InSAR analysis, time dependent modeling and data handling allows us to investigate spatiotemporal variation of the creep at Hayward fault in response to small changes in the regional stress field, for instance, due to a 2007 Mw 4.2 Oakland earthquake.

  5. Seismic and Aseismic Slip on the San-Jacinto Fault Near Anza, CA, from Joint Analysis of Strain and Aftershock Data

    NASA Astrophysics Data System (ADS)

    Inbal, A.; Avouac, J. P.; Ampuero, J. P.

    2014-12-01

    The San-Jacinto Fault (SJF) is the most active fault in southern California, which together with the southern San-Andreas Fault accommodates a large fraction of the motion across the plate boundary. Seismicity along the SJF is distributed over several fault segments with distinct spatio-temporal characteristics. One of these segments, known as the Anza seismic gap, is a 25 km long strand almost devoid of seismicity. In recent years, four M4-5 events occurred SE of the gap. Despite their moderate magnitudes, these earthquakes triggered rich aftershock sequences and pronounced afterslip that lasted for several weeks, and was well captured by nearby PBO borehole strain meters. A similar transient was remotely triggered by the 2010 El Mayor-Cucapah earthquake. Geodetic and seismic observations following a local M5.4 mainshock indicate that afterslip propagated unilaterally towards the NW at speed of about 5 km/day. We infer the distribution of slip via a joint inversion of the aftershock and strain data. Our approach is based on Dieterich's (1994) model relating the evolution of seismicity rate to applied stresses, within the framework of rate-and-state friction. This approach provides resolution power at depths inaccessible to the surface geodetic network. Moreover, it allows us to gain important insights onto the fault mechanical properties. We apply this inversion scheme to episodes that occurred during 2010. Remarkably, we find that the cumulative moment released post-seismically during the locally triggered transient is 5-10 times larger than the moment of the mainshock. We show that the data favour a model in which deep slip transients, which may develop due to local or remote earthquakes, occur on a weak, close-to-velocity-neutral fault. The transients increase the stress along the Anza gap, and trigger earthquakes outside it through static stress transfer.

  6. Slip partitioning

    NASA Astrophysics Data System (ADS)

    Bowman, D.; King, G.

    2003-04-01

    Oblique motion along tectonic boundaries is commonly partitioned into slip on several faults with different senses of motion. This partitioning can be explained by the upward propagation of a localized fault at depth. The static stress field ahead of the propagating fault separates into zones of predominantly normal, reverse and strike-slip faulting. Elastic approximations to plastic behavior are used to explain the distribution of faults observed along the San Andreas (California, USA) and the Haiyuan faults (Tibet, China). The process is appropriate to explain any partitioned system, and has important implications for the driving forces of earthquakes and fault friction.

  7. Slip sensor

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.

    1980-01-01

    Slippage of one surface, relative to another is detected by "ball bearing" magnetic sensor. Omnidirectional sensor responds to slippage in any direction. Sensor is mounted in "finger" of mechanical claw manipulator and signals operator who tightens grip by remote control when object slips.

  8. Kinematic Slip Model for 12 May 2008 Wenchuan-Beichuan Mw 7.9 Earthquake from Joint Inversion of ALOS, Envisat, and Teleseismic Data

    NASA Technical Reports Server (NTRS)

    Fielding, Eric; Sladen, Anthony; Avouac, Jean-Philippe; Li, Zhenhong; Ryder, Isabelle; Burgmann, Roland

    2008-01-01

    The presentations explores kinematics of the Wenchaun-Beichuan earthquake using data from ALOS, Envisat, and teleseismic recordings. Topics include geomorphic mapping, ALOS PALSAR range offsets, ALOS PALSAR interferometry, Envisat IM interferometry, Envisat ScanSAR, Joint GPS-InSAR inversion, and joint GPS-teleseismic inversion (static and kinematic).

  9. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  10. Earthquake Slip Classroom Exercise

    NSDL National Science Digital Library

    In this activity, students explore the 'stick-slip' mechanism of earthquake generation. They will learn about the concepts of stick-slip sliding, static friction, energy conversion, and the elastic properties of materials. Students work together to develop and test a hypothesis, make measurements, graph and write a short report on the results.

  11. Are non-slip socks really 'non-slip'? An analysis of slip resistance

    Microsoft Academic Search

    Satyan Chari; Terrence Haines; Paul Varghese; Alyssia Economidis

    2009-01-01

    BACKGROUND: Non-slip socks have been suggested as a means of preventing accidental falls due to slips. This study compared the relative slip resistance of commercially available non-slip socks with other foot conditions, namely bare feet, compression stockings and conventional socks, in order to determine any traction benefit. METHODS: Phase one involved slip resistance testing of two commercially available non-slip socks

  12. SlipKnot Home Page

    NSDL National Science Digital Library

    SlipKnot (w/o SLIP) MicroMind, New York, NY, US SlipKnot is a graphical World Wide Web browser specifically designed for Microsoft Windows users who have UNIX shell accounts with their service providers. Its primary feature is that it does not require SLIP or PPP or TCP/IP services. SlipKnot is distributed as restricted shareware, with a registration fee.

  13. The frictional properties of joints in rock

    Microsoft Academic Search

    J. C. Jaeger

    1959-01-01

    Summary The conditions for sliding over artificial joint surfaces have been studied experimentally by cutting rock cylinders at various angles to their axes and studying slip over these surfaces in a triaxial testing apparatus. The types of joint used were: (i) filled with plaster to simulate a soft joint filling, (ii) bare surfaces ground approximately flat, and (iii) natural surfaces

  14. Physics of Slip Partitioning

    NASA Astrophysics Data System (ADS)

    Bowman, D. D.; King, G. C.

    2002-12-01

    Oblique motion along tectonic boundaries is commonly partitioned into slip on several faults with different senses of motion. This partitioning can be explained by the upward propagation of a localized fault at depth. The static stress field ahead of the propagating fault separates into zones of predominantly normal, reverse and strike-slip faulting. Elastic approximations to plastic behavior are used to explain the distribution of faults observed along the San Andreas (California, USA) and the Haiyuan faults (Tibet, China). The process is appropriate to explain any partitioned system, and has important implications for the driving forces of earthquakes and fault friction.

  15. Nucleation and growth of strike slip faults in granite.

    USGS Publications Warehouse

    Segall, P.; Pollard, D.P.

    1983-01-01

    Fractures within granodiorite of the central Sierra Nevada, California, were studied to elucidate the mechanics of faulting in crystalline rocks, with emphasis on the nucleation of new fault surfaces and their subsequent propagation and growth. Within the study area the fractures form a single, subparallel array which strikes N50o-70oE and dips steeply to the S. Some of these fractures are identified as joints because displacements across the fracture surfaces exhibit dilation but no slip. The joints are filled with undeformed minerals, including epidote and chlorite. Other fractures are identified as small faults because they display left-lateral strike slip separations of up to 2m. Slickensides, developed on fault surfaces, plunge 0o-20o to the E. The faults occur parallel to, and in the same outcrop with, the joints. The faults are filled with epidote, chlorite, and quartz, which exhibit textural evidence of shear deformation. These observations indicate that the strike slip faults nucleated on earlier formed, mineral filled joints. Secondary, dilational fractures propagated from near the ends of some small faults contemporaneously with the left-lateral slip on the faults. These fractures trend 25o+ or -10o from the fault planes, parallel to the direction of inferred local maximum compressive stress. The faults did not propagate into intact rock in their own planes as shear fractures. -from Authors

  16. Polycrystal Plasticity -Multiple Slip"

    E-print Network

    Rollett, Anthony D.

    Polycrystal Plasticity - Multiple Slip" 27-750 Texture, Microstructure & Anisotropy A.D. Rollett;2 Objective" The objective of this lecture is to show how plastic deformation in polycrystals requires of Los Alamos polycrystal plasticity, LApp; also the Viscoplastic Selfconsistent code, VPSC; also

  17. Low-Friction Joint for Robot Fingers

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F.

    1985-01-01

    Mechanical linkage allows adjacent parts to move relative to each other with low friction and with no chatter, slipping, or backlash. Low-friction joint of two surfaces in rolling contact, held in alinement by taut flexible bands. No sliding friction or "stick-slip" motion: Only rolling-contact and bending friction within bands. Proposed linkage intended for finger joints in mechanical hands for robots and manipulators.

  18. A Reduced Order, One Dimensional Model of Joint Response

    SciTech Connect

    DOHNER,JEFFREY L.

    2000-11-06

    As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.

  19. Universal behavior in ideal slip

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Smith, John R.

    1991-01-01

    The slip energies and stresses are computed for defect-free crystals of Ni, Cu, Ag, and Al using the many-atom approach. A simple analytical expression for the slip energies is obtained, leading to a universal form for slip, with the energy scaled by the surface energy and displacement scaled by the lattice constant. Maximum stresses are found to be somewhat larger than but comparable with experimentally determined maximum whisker strengths.

  20. Mechanism of slip and twinning

    NASA Technical Reports Server (NTRS)

    Rastani, Mansur

    1992-01-01

    The objectives are to: (1) demonstrate the mechanisms of deformation in body centered cubic (BCC), face centered cubic (FCC), and hexagonal close-packed (HCP)-structure metals and alloys and in some ceramics as well; (2) examine the deformed microstructures (slip lines and twin boundaries) in different grains of metallic and ceramic specimens; and (3) study visually the deformed macrostructure (slip and twin bands) of metals and alloys. Some of the topics covered include: deformation behavior of materials, mechanisms of plastic deformation, slip bands, twin bands, ductile failure, intergranular fracture, shear failure, slip planes, crystal deformation, and dislocations in ceramics.

  1. Are non-slip socks really 'non-slip'? An analysis of slip resistance

    PubMed Central

    Chari, Satyan; Haines, Terrence; Varghese, Paul; Economidis, Alyssia

    2009-01-01

    Background Non-slip socks have been suggested as a means of preventing accidental falls due to slips. This study compared the relative slip resistance of commercially available non-slip socks with other foot conditions, namely bare feet, compression stockings and conventional socks, in order to determine any traction benefit. Methods Phase one involved slip resistance testing of two commercially available non-slip socks and one compression-stocking sample through an independent blinded materials testing laboratory using a Wet Pendulum Test. Phase two of the study involved in-situ testing among healthy adult subjects (n = 3). Subjects stood unsupported on a variable angle, inclined platform topped with hospital grade vinyl, in a range of foot conditions (bare feet, non-slip socks, conventional socks and compression stockings). Inclination was increased incrementally for each condition until slippage of any magnitude was detected. The platform angle was monitored using a spatial orientation tracking sensor and slippage point was recorded on video. Results Phase one results generated through Wet Pendulum Test suggested that non-slip socks did not offer better traction than compression stockings. However, in phase two, slippage in compression stockings was detected at the lowest angles across all participants. Amongst the foot conditions tested, barefoot conditions produced the highest slip angles for all participants indicating that this foot condition provided the highest slip resistance. Conclusion It is evident that bare feet provide better slip resistance than non-slip socks and therefore might represent a safer foot condition. This study did not explore whether traction provided by bare feet was comparable to 'optimal' footwear such as shoes. However, previous studies have associated barefoot mobilisation with increased falls. Therefore, it is suggested that all patients continue to be encouraged to mobilise in appropriate, well-fitting shoes whilst in hospital. Limitations of this study in relation to the testing method, participant group and sample size are discussed. PMID:19706167

  2. SLIP CASTING OF MAGNESIATITANIA BODIES

    Microsoft Academic Search

    Rosenfels

    1961-01-01

    Titania is known to increase the rate of diffusion and sintering in ; pressed magnesia-titania bodies. To meet a need for dense ceramic containers ; which would hold a molten chloride eutectic, methods were developed for slip ; casting and sintering fused magnesia containing 10 wt% titania. The procedures ; were based on the Los Alamos method of slip casting

  3. Joint swelling

    MedlinePLUS

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  4. An analysis of a joint shear model for jointed media with orthogonal joint sets; Yucca Mountain Site Characterization Project

    SciTech Connect

    Koteras, J.R.

    1991-10-01

    This report describes a joint shear model used in conjunction with a computational model for jointed media with orthogonal joint sets. The joint shear model allows nonlinear behavior for both joint sets. Because nonlinear behavior is allowed for both joint sets, a great many cases must be considered to fully describe the joint shear behavior of the jointed medium. An extensive set of equations is required to describe the joint shear stress and slip displacements that can occur for all the various cases. This report examines possible methods for simplifying this set of equations so that the model can be implemented efficiently form a computational standpoint. The shear model must be examined carefully to obtain a computationally efficient implementation that does not lead to numerical problems. The application to fractures in rock is discussed. 5 refs., 4 figs.

  5. Hypermobile joints

    MedlinePLUS

    ... hypermobile joints have an increased risk for joint dislocation and other problems. Extra care may be needed ... the joint? Is there any history of joint dislocation, difficulty walking, or difficulty using the arms? Further ...

  6. A computational model for three-dimensional jointed media with a single joint set; Yucca Mountain Site Characterization Project

    SciTech Connect

    Koteras, J.R.

    1994-02-01

    This report describes a three-dimensional model for jointed rock or other media with a single set of joints. The joint set consists of evenly spaced joint planes. The normal joint response is nonlinear elastic and is based on a rational polynomial. Joint shear stress is treated as being linear elastic in the shear stress versus slip displacement before attaining a critical stress level governed by a Mohr-Coulomb faction criterion. The three-dimensional model represents an extension of a two-dimensional, multi-joint model that has been in use for several years. Although most of the concepts in the two-dimensional model translate in a straightforward manner to three dimensions, the concept of slip on the joint planes becomes more complex in three dimensions. While slip in two dimensions can be treated as a scalar quantity, it must be treated as a vector in the joint plane in three dimensions. For the three-dimensional model proposed here, the slip direction is assumed to be the direction of maximum principal strain in the joint plane. Five test problems are presented to verify the correctness of the computational implementation of the model.

  7. Synchronization of phase slips in chaotic map

    NASA Astrophysics Data System (ADS)

    Arai, Kenichi; Mizutani, Shin

    2004-05-01

    We show that when paced chaotic oscillators, which can be flows or maps, are coupled appropriately, phase slips produced by each oscillator are synchronized. If a periodically driven chaotic oscillator strays from a phase synchronization region, the phase difference between the oscillator and the pacer jumps intermittently by 2?, which is called a phase slip. When two sinusoidally forced Roessler oscillators are coupled appropriately, phase slips produced by the two oscillators occur simultaneously, that is the phase slips are synchronized. We also show that if the coupled oscillator deviates slightly from the slip synchronization region, a portion of the simultaneous phase slips are desynchronized, namely only one of the two oscillators produces a phase slip. Such phenomena as synchronized phase slips and partially synchronized phase slips can be reproduced by a coupled map system. We investigate some statistical properties and dynamical structures of the phenomena by investigating the coupled map system.

  8. Bulk Metallic Glasses Deform via Slip Avalanches

    E-print Network

    James Antonaglia; Wendelin J. Wright; Xiaojun Gu; Rachel R. Byer; Todd C. Hufnagel; Michael LeBlanc; Jonathan T. Uhl; Karin A. Dahmen

    2013-12-21

    Inelastic deformation of metallic glasses occurs via slip events with avalanche dynamics similar to those of earthquakes. For the first time in these materials, measurements have been obtained with sufficiently high temporal resolution to extract both the exponents and the scaling functions that describe the nature, statistics and dynamics of the slips according to a simple mean-field model. These slips originate from localized deformation in shear bands. The mean-field model describes the slip process as an avalanche of rearrangements of atoms in shear transformation zones (STZs). Small slips show the predicted power-law scaling and correspond to limited propagation of a shear front, while large slips are associated with uniform shear on unconstrained shear bands. The agreement between the model and data across multiple independent measures of slip statistics and dynamics provides compelling evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses.

  9. What Is an Earthquake?: Oblique Slip

    NSDL National Science Digital Library

    Some faults experience appreciable amounts of dip slip and strike slip simultaneously, and the nomenclature of these faults reflects this. This is an exercise regarding the nomenclature of faults that experience appreciable amounts of dip slip and strike slip simultaneously. In this activity, learners view animations of these faults and attempt to correctly interpret the sense of motion. Clicking on the completed animation provides the correct answer.

  10. Frictional melt and seismic slip

    Microsoft Academic Search

    S. Nielsen; G. Di Toro; T. Hirose; T. Shimamoto

    2008-01-01

    Frictional melt is implied in a variety of processes such as seismic slip, ice skating, and meteorite combustion. A steady state can be reached when melt is continuously produced and extruded from the sliding interface, as shown recently in a number of laboratory rock friction experiments. A thin, low-viscosity, high-temperature melt layer is formed resulting in low shear resistance. A

  11. The distributions of slip rate and ductile deformation in a strike-slip shear zone

    E-print Network

    Rolandone, Frederique

    , deformation occurs in both brittle and ductile regimes. In many studies, it is assumed that litho- sphereThe distributions of slip rate and ductile deformation in a strike- slip shear zone Fre law for the partitioning between slip rate on a strike-slip fault and distributed deformation

  12. Automatic Slip Control for Railway Vehicles

    Microsoft Academic Search

    Daniel Frylmark

    2003-01-01

    Abstract: In the railway industry, slip control hasalwaysbeen essential due tothe lowfrictionbetween the wheels and the rail. In this master's thesiswe have gathered several slip control methods and evaluated them.These evaluations were performed in Matlab-Simulink on slip processmodel of r ilw y vehicle. Theobjective with these ev lu tionswere to show dv nt ges nd dis dv nt ges with

  13. 24 CFR 3280.605 - Joints and connections.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...to the full depth of the solder cup or welding sockets of each fitting. Pipe threads and slip joints shall not be wrapped with string, paper, putty, or similar fillers. (2) Threaded joints. Threads for screw pipe and fittings shall conform to...

  14. Fault roughness evolution with slip (Gole Larghe Fault Zone, Italian Alps)

    NASA Astrophysics Data System (ADS)

    Bistacchi, A.; Spagnuolo, E.; Di Toro, G.; Nielsen, S. B.; Griffith, W. A.

    2011-12-01

    Fault surface roughness is a principal factor influencing fault and earthquake mechanics. However, little is known on roughness of fault surfaces at seismogenic depths, and particularly on how it evolves with accumulating slip. We have studied seismogenic fault surfaces of the Gole Larghe Fault Zone, which exploit precursor cooling joints of the Adamello tonalitic pluton (Italian Alps). These faults developed at 9-11 km and 250-300°C. Seismic slip along these surfaces, which individually accommodated from 1 to 20 m of net slip, resulted in the production of cm-thick cataclasites and pseudotachylytes (solidified melts produced during seismic slip). The roughness of fault surfaces was determined with a multi-resolution aerial and terrestrial LIDAR and photogrammetric dataset (Bistacchi et al., 2011, Pageoph, doi: 10.1007/s00024-011-0301-7). Fault surface roughness is self-affine, with Hurst exponent H < 1, indicating that faults are comparatively smoother at larger wavelengths. Fault surface roughness is inferred to have been inherited from the precursor cooling joints, which show H ? 0.8. Slip on faults progressively modified the roughness distribution, lowering the Hurst exponent in the along-slip direction up to H ? 0.6. This behaviour has been observed for wavelengths up to the scale of the accumulated slip along each individual fault surface, whilst at larger wavelengths the original roughness seems not to be affected by slip. Processes that contribute to modify fault roughness with slip include brittle failure of the interacting asperities (production of cataclasites) and frictional melting (production of pseudotachylytes). To quantify the "wear" due to these processes, we measured, together with the roughness of fault traces and their net slip, the thickness and distribution of cataclasites and pseudotachylytes. As proposed also in the tribological literature, we observe that wearing is scale dependent, as smaller wavelength asperities have a shorter interaction distance and are consumed faster with slip than larger ones. However, in faults, production of cataclasites and pseudotachylytes changes the contact area of sliding surfaces by interposing a layer of wear products. This layer may preserve from wearing asperities that are smaller in amplitude than the layer thickness, thus providing a mechanism that is likely to preserve small amplitude/wavelength roughness. These processes have been considered in a new spectral model of wear, which allows to model wear for self-affine surfaces and includes the accumulation of wear products within the fault zone. This model can be used to generalize our results and contribute to reconstruct a realistic model of a seismogenic fault zone (http://roma1.rm.ingv.it/laboratori/laboratorio-hp-ht/usems-project).

  15. How do Faults Slip: Earthquakes versus Episodic Tremor and Slip

    NSDL National Science Digital Library

    Mike Brudzinski

    Despite what we have learned from the theory of plate tectonics, the specifics of how those plate motions contribute to movement along faults remain a matter of much debate. Since the discovery of plate tectonics, scientists have recognized that earthquake activity, both the orientation and magnitude, is related to plate motions. However, efforts to total up the motion simply associated with earthquakes often falls far short of the plate motions. This suggests that plates have a way to slide past one another along faults without generating earthquakes, and discovering what controls whether faults produce earthquakes is critical for better characterizing seismic hazards around the world. Scientists are using a combination of GPS and seismometer recordings to investigate this issue. Some portions of a fault reveal traditional earthquake stick-slip behavior where gradual GPS motions show the fault is locked for a long time while plate motions cause stress to accumulate at the fault until the rocks break and the fault moves over the span of minutes generating large seismic signals and an abrupt GPS motion. In 2003, researchers discovered that portions of a fault also release accumulated stress more gradually over the course of several weeks in the form of a slow slip event that is accompanied by weak seismic tremors observed in a narrow frequency range that requires specific filtering to observe. These new phenomena are described as episodic tremor and slip as they recur on nearly an annual basis, much more frequently than large earthquakes which can have recurrence intervals of 50-5000 years. To better understand how faults move, this activity will examine both GPS and seismic data in the Cascadia region to identify key observations and build interpretation from them.

  16. Small World Property of a Rock Joint(Complexity of Frictional Interfaces: A Complex Network Perspective)

    Microsoft Academic Search

    Hamed O. Ghaffari; M. Sharifzadeh; E. Evgin

    2010-01-01

    The shear strength and stick-slip behavior of a rough rock joint are analyzed using the complex network approach. We develop a network approach on correlation patterns of void spaces of an evolvable rough fracture (crack type II). Correlation among networks properties with the hydro -mechanical attributes (obtained from experimental tests) of fracture before and after slip is the direct result

  17. The 1964 Prince William Sound earthquake: Joint inversion of tsunami and geodetic data

    Microsoft Academic Search

    Jean M. Johnson; Kenji Satake; Sanford R. Holdahl; Jeanne Sauber

    1996-01-01

    The 1964 Prince William Sound (Alaska) earthquake, Mw=9.2, ruptured a large area beneath the continental margin of Alaska from Prince William Sound to Kodiak Island. A joint inversion of tsunami waveforms and geodetic data, consisting of vertical displacements and horizontal vectors, gives a detailed slip distribution. Two areas of high slip correspond to seismologically determined areas of high moment release:

  18. Process for slip casting textured tubular structures

    DOEpatents

    Steinlage, Greg A. (West Lafayette, IN); Trumble, Kevin P. (West Lafayette, IN); Bowman, Keith J. (West Lafayette, IN)

    2002-01-01

    A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

  19. Spatial and Temporal Evolution of Fault Slip on the Longitudinal Valley Fault Taiwan

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Avouac, J.; Champenois, J.; Lee, J.

    2012-12-01

    The Longitudinal Valley Fault (LVF) in Eastern Taiwan is an exceptional example of a fault with high slip rate that produces both seismic and aseismic slip. This particular fault accounts for more than a third of the 9 cm/yr oblique convergence rate across Taiwan. Deformation of anthropogenic features shows that aseismic creep accounts for a significant fraction of fault slip near the surface whereas a fraction of the slip is also seismic since this fault has produced large M>6.5 earthquakes in 1951 and 2003. In this study, we analyze a dense set of geodetic and seismological data around the LVF including campaign-mode GPS measurements, times-series of daily solutions for Continuous GPS stations (CGPS), accelerometeric records of the 2003 Chenkung earthquake, and leveling measurements. To enhance the spatial resolution provided by these data we complement them with inSAR measurements produced from a series of ALOS images processed with the permanent scatter technique. The data, which cover the entire LVF and span the period from 1992 to 2010 are inverted for the temporal evolution of fault slip a depth using the Principal Component Analysis base Inversion Method (PCAIM). The technique allows the joint inversion of these diverse data, thus taking the advantage of the spatial resolution afforded by the inSAR data and the temporal resolution afforded by the CGPS data. We find that 1- seismic slip during the 2003 Chengkung earthquake occurred on a fault patch which had remained partially locked in the interseismic period; 2- the seismic rupture propagated partially into a zone of shallow aseismic interseismic creep but failed to reach the surface; 3- that aseismic afterslip occurred around but mostly updip of the ruptured area. The study allows estimating the fault slip budget (the fraction of aseismic and seismic slip) over the seismogenic depth range, and placing constraints on the fault frictional properties and their variations with space.

  20. Constraining the roughness degree of slip heterogeneity

    Microsoft Academic Search

    Mathieu Causse; Fabrice Cotton; P. M. Mai

    2010-01-01

    This article investigates different approaches for assessing the degree of roughness of the slip distribution of future earthquakes. First, we analyze a database of slip images extracted from a suite of 152 finite-source rupture models from 80 events (Mw = 4.1–8.9). This results in an empirical model defining the distribution of the slip spectrum corner wave numbers (kc) as a

  1. Slip asymmetry in the molecular crystal cyclotrimethylenetrinitramine

    NASA Astrophysics Data System (ADS)

    Mathew, N.; Picu, R. C.

    2013-09-01

    Slip asymmetry is a common occurrence in some monatomic crystals where it is due to complex core structures or specific packing of slip planes. Here we present another mechanism, based on molecular steric hindrance, which leads to asymmetric dislocation motion in cyclotrimethylenetrinitramine (RDX) molecular crystal. Dislocations move at different critical stresses when shear is applied in the positive and negative directions of the Burgers vector in the slip system that contributes most to plastic deformation.

  2. Bulk metallic glasses deform via slip avalanches.

    PubMed

    Antonaglia, James; Wright, Wendelin J; Gu, Xiaojun; Byer, Rachel R; Hufnagel, Todd C; LeBlanc, Michael; Uhl, Jonathan T; Dahmen, Karin A

    2014-04-18

    For the first time in metallic glasses, we extract both the exponents and scaling functions that describe the nature, statistics, and dynamics of slip events during slow deformation, according to a simple mean field model. We model the slips as avalanches of rearrangements of atoms in coupled shear transformation zones (STZs). Using high temporal resolution measurements, we find the predicted, different statistics and dynamics for small and large slips thereby excluding self-organized criticality. The agreement between model and data across numerous independent measures provides evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses. PMID:24785049

  3. Geodetic Measurements of the Guerrero Slow Slip Events: Implications for Large Earthquakes in the Guerrero Gap

    NASA Astrophysics Data System (ADS)

    Bekaert, D. P.; Hooper, A. J.; Samsonov, S. V.; Wright, T. J.; González, P. J.; Pathier, E.; Kostoglodov, V.

    2014-12-01

    Estimates of elastic strain accumulated in the Guerrero seismic gap, Mexico, have conceived a potential for Mw 8.0-8.4 subduction thrust earthquake. While several large slow slip events (SSEs) have occurred in the area it remains unclear how the SSEs change the stress field in the Guerrero seismic region, and what their implications are for future devastating earthquakes. On 18 April 2014, the Mw 7.2 Petatlan earthquake, followed by two Mw 6.4 and 6.1 events on 8 and 10 May 2014, occurred on the western edge of the Gap, while a new large slow slip event was ongoing, suggesting that it may have triggered the earthquakes. Slow slip studies have mainly relied on GNSS. In Guerrero the low station distribution restricts their ability to resolve the spatial extent of the SSE. We apply a time-series Interferometric Synthetic Aperture Radar (InSAR) analysis to estimate the spatial extent and magnitude of deformation caused by a slow slip event in 2006, and jointly invert GNSS and InSAR for slow slip on the subduction interface. We assume rectangular dislocation patches, and use Markov chain Monte Carlo sampling to obtain a full error distribution of the model unknowns. Correlation between our estimated slow slip region and the location of non-volcanic tremor, as well as an ultra-slow velocity layer, supports the hypothesis of a common source potentially related to high pore pressures. We find slow slip extends up to 7 km depth, well within the Guerrero Gap. We observe a spatial correlation between slow slip and a high slip deficit region. Even accounting for the stress released by SSEs, we find the Guerrero Gap still has a potential for Mw ~7.8-8 earthquake. We also present results for the 2014 SSE, using RADARSAT-2 data. We analyse whether slow slip could triggered the recent earthquakes, by investigating the spatial extent of the SSE and its relationship to the coseismic slip. Our results have implications for the timings of megathrust earthquakes in other subduction zones.

  4. Stick and slip actuators (SSA)

    NASA Astrophysics Data System (ADS)

    Schmitt, Carl; Breguet, Jean-Marc; Bergander, Arvid; Clavel, Reymond

    2000-10-01

    Stick and Skip Actuators (SSA) are particularly well adapted to micro- robotics. A simple design, a very high intrinsic resolution (a few nanometers) and a high rigidity make them especially interesting in high precision micro-manipulations. Moreover, a smart design allows to combine the guiding and actuating function. The mechanical interface between the piezo-elements and the guiding mechanisms in an important point of the stick and slip actuators. The design of this interface and the choice of the material are very important. Both aspects have an impact on the rigidity, which has an influence on the behavior of the actuator. They have also an incidence onf the reliability (lifetime) because the design gives the contact condition and the material the wear resistance. In addition, a loading system allowing to keep the mechanical contact at this interface has a direct effect on the contact pressure. In order to confirm the performance of SSA, prototypes have been developed at the ISR. Their designs have bene made for application in optical microscopy, for manipulators in industrial assembly of micro- engineering products, for micro-factory, chemical and bio-engineering equipment for research or routine tasks, such as testing, screening etc. This paper presents a short description of several SSA made by the IRS and describes the parameters characterizing the stick and slip motion and the mechanical interface.

  5. Ice Sheet Stratigraphy Can Constrain Basal Slip

    NASA Astrophysics Data System (ADS)

    Wolovick, M.; Creyts, T. T.; Buck, W. R.; Bell, R. E.

    2014-12-01

    Basal slip is an important component of ice sheet mass flux and dynamics. Basal slip varies over time due to variations in basal temperature, water pressure, and sediment cover. All of these factors can create coherent patterns of basal slip that migrate over time. Our knowledge of the spatial variability in basal slip comes from inversions of driving stress, ice thickness, and surface velocity, but these inversions contain no information about temporal variability. We do not know if the patterns in slip revealed by those inversions move over time. While englacial stratigraphy has classically been used to constrain surface accumulation and geothermal flux, it is also sensitive to horizontal gradients in basal slip. Here we show that englacial stratigraphy can constrain the velocity of basal slip patterns. Englacial stratigraphy responds strongly to patterns of basal slip that move downstream over time close to the ice sheet velocity. In previous work, we used a thermomechanical model to discover that thermally controlled slip patterns migrate downstream and create stratigraphic structures, but we were unable to directly control the pattern velocity, as that arose naturally out of the model physics. Here, we use a kinematic flowline model that allows us to directly control pattern velocity, and thus is applicable to a wide variety of slip mechanisms in addition to basal temperature. We find that the largest and most intricate stratigraphic structures develop when the pattern moves at the column-average ice velocity. Patterns that move slower than the column-average ice velocity produce overturned stratigraphy in the lower part of the ice sheet, while patterns moving at the column-average eventually cause the entire ice sheet to overturn if they persist long enough. Based on these forward models, we develop an interpretive guide for deducing moving patterns in basal slip from ice sheet internal layers. Ice sheet internal stratigraphy represents a potentially vast untapped source of information on basal sliding.

  6. Kinematics of the foot during slips

    Microsoft Academic Search

    April J. Chambers; Raki ´ e Chama

    Slip and fall accidents are often listed among the leading generators of injuries. The goals of this study were to (1) describe the foot kinematics during unexpected slips, and (2) to compare the foot kinematics during gait in unexpected slippery environment and when warnings of slippery environments are provided. Five participants walked on dry and glycerol- contaminated floors, while varying

  7. SLIP PREVENTION IN WALKING - LOWER EXTREMITY BIOMECHANICS

    Microsoft Academic Search

    Daniel Tik-Pui Fongl; Youlian Hong; Jing-Xian U; Kai-Ming Chan

    This study investigated the human slip prevention strategies when walking on slippery surfaces. Fifteen male subjects performed, level walking without slips under sixteen simulated construction site environments. Kinematics, kinetics and electromyography parameters were collected. The slipperiness of the walkway conditions were quantified by the dynamic coefficient of friction (DCOF). Gait changes in slippery condition included prolonged force and pressure exertion

  8. Slip Prediction Using Visual Information Anelia Angelova

    E-print Network

    Perona, Pietro

    prediction of slip from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobil- ity of a wheeled ground robot while driving. High levels of slip can be observed on certain terrains, which can

  9. Volcanism and aseismic slip in subduction zones

    Microsoft Academic Search

    Hemendra Acharya

    1981-01-01

    The spatial and temporal relationship of volcanism to the occurrence of large earthquakes and convergent plate motion is examined. The number of volcanic eruptions per year in a convergent zone is found to be linearly related to the aseismic slip component of plate motion. If the aseismic slip rate is low (coupling between converging plates is strong), then the primary

  10. Slip versus Friction : Modifying the Navier condition

    NASA Astrophysics Data System (ADS)

    Kotsalis, Evangelos; Walther, Jens; Koumoutsakos, Petros

    2006-03-01

    The modeling of fluid-solid interfaces remains one of the key challenges in fluid mechanics. The prevailing model, attributed to Navier, defines the fluid ``slip'' velocity as proportional to the wall shear and a parameter defined as the slip length. Several works have in turn proposed models for this slip length but no universal model for the slip velocity has been accepted. We present results from large scale molecular dynamics simulations of canonical flow problems, indicating, that the inadequacy of this classic model, stems from not properly accounting for the pressure field. We propose and validate a new model, based on the fundamental observation that the finite ``slip'' velocity is a result of an imbalance between fluid and solid intermolecular forces. An excess force on the fluid elements will lead to their acceleration which in turn may result in a slip velocity at the interface. We formulate the slip velocity in terms of fluid-solid friction Ff and propose a generalized boundary condition: Ff= Fs+ Fp= ?uus+ ?pp where p denotes the pressure, and ?uand ?p the viscous and static friction coefficients, for which universal constants are presented. We demonstrate that the present model can overcome difficulties encountered by the classical slip model in canonical flow configurations.

  11. Salton Sea Satellite Image Showing Fault Slip

    USGS Multimedia Gallery

    Landsat satellite image (LE70390372003084EDC00) showing location of surface slip triggered along faults in the greater Salton Trough area. Red bars show the generalized location of 2010 surface slip along faults in the central Salton Trough and many additional faults in the southwestern section of t...

  12. Frictional melting of peridotite and seismic slip

    Microsoft Academic Search

    P. Del Gaudio; G. Di Toro; R. Han; T. Hirose; S. Nielsen; T. Shimamoto; A. Cavallo

    2009-01-01

    The evolution of the frictional strength along a fault at seismic slip rates (about 1 m\\/s) is a key factor controlling earthquake mechanics. At mantle depths, friction-induced melting and melt lubrication may influence earthquake slip and seismological data. We report on laboratory experiments designed to investigate dynamic fault strength and frictional melting processes in mantle rocks. We performed 20 experiments

  13. SLIP running with an articulated robotic leg

    Microsoft Academic Search

    Marco Hutter; C. David Remy; Mark A. Höpflinger; Roland Siegwart

    2010-01-01

    SLIP models are generally known as one of the best and simplest abstractions describing the spring-like leg behavior found in human and animal running, and have thus been subject to exhaustive investigation. To exploit these findings in real robots, we utilize an operational space controller that projects the behavior of the SLIP model onto the dynamics of an actual segmented

  14. Preseismic fault slip and earthquake prediction

    Microsoft Academic Search

    J. H. Dieterich

    1978-01-01

    It is proposed that preseismic fault creep may be the underlying process that is responsible for observations of earthquake precursors. The assertion that fault creep precedes earthquakes is supported by evidence from at least some earthquakes and by analogy with detailed laboratory observations. Laboratory observations of stick slip reveal that at least two stages of preseismic slip are an intrinsic

  15. Tensorial slip of super-hydrophobic channels

    E-print Network

    Schmieschek, Sebastian; Harting, Jens; Vinogradova, Olga I

    2011-01-01

    We describe a generalization of the tensorial slip boundary condition, originally justified for a thick (compared to texture period) channel, to any channel thickness. The eigenvalues of the effective slip length tensor, however, in general case become dependent on the gap and cannot be viewed as a local property of the surface, being a global characteristic of the channel. To illustrate the use of the tensor formalism we develop a semi-analytical theory of an effective slip in a parallel-plate channel with one super-hydrophobic striped and one hydrophilic surface. Our approach is valid for any local slip at the gas sectors and an arbitrary distance between the plates, ranging from a thick to a thin channel. We then present results of lattice Boltzmann simulations to validate the analysis. Our results may be useful for extracting effective slip tensors from global measurements, such as the permeability of a channel, in experiments or simulations.

  16. [Evaporating Droplet and Imaging Slip Flows

    NASA Technical Reports Server (NTRS)

    Larson, R. G.

    2002-01-01

    In this report, we summarize work on Evaporating Droplet and Imaging Slip Flows. The work was primarily performed by post-doc Hue Hu, and partially by grad students Lei Li and Danish Chopra. The work includes studies on droplet evaporation and its effects on temperature and velocity fields in an evaporating droplet, new 3-D microscopic particle image velocimetry and direct visualization on wall slip in a surfactant solution. With the exception of the slip measurements, these projects were those proposed in the grant application. Instead of slip flow, the original grant proposed imaging electro-osmotic flows. However, shortly after the grant was issued, the PI became aware of work on electro-osmotic flows by the group of Saville in Princeton that was similar to that proposed, and we therefore elected to carry out work on imaging slip flows rather than electro-osmotic flows.

  17. The role of water in slip casting

    NASA Technical Reports Server (NTRS)

    Mccauley, R. A.; Phelps, G. W.

    1984-01-01

    Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface.

  18. Spatio-temporal evolution of seismic and aseismic slip on the Longitudinal Valley Fault, Taiwan

    NASA Astrophysics Data System (ADS)

    Thomas, M. Y.; Avouac, J.; Champenois, J.; Lee, J.

    2013-12-01

    The Longitudinal Valley Fault (LVF) in Eastern Taiwan is a high slip rate fault (about 5cm/yr) which exhibits both seismic and aseismic slip. Deformation of anthropogenic features shows that aseismic creep accounts for a significant fraction of fault slip near the surface whereas a fraction of the slip is also seismic since this fault has produced large earthquakes with five Mw>6.8 events in 1951 and 2003. In this study, we analyze a dense set of geodetic and seismological data around the LVF including campaign-mode GPS measurements, times-series of daily solutions for continuous GPS stations (cGPS), leveling data and accelerometric records of the 2003 Chenkung earthquake. To enhance the spatial resolution provided by these data, we complement them with InSAR measurements produced from a series of ALOS images processed using a persistent scatterer (PS) technique. The combined dataset covers the entire LVF and spans the period from 1992 to 2010. We invert this data to infer the temporal evolution of fault slip at depth using the Principal Component Analysis based Inversion Method (PCAIM). This technique allows the joint inversion of diverse data, taking the advantage of the spatial resolution given by the InSAR measurements and the temporal resolution afforded by the cGPS data. We find that (1) seismic slip during the 2003 Chengkung earthquake occurred on a fault patch which had remained partially locked in the interseismic period; (2) the seismic rupture propagated partially into a zone of shallow aseismic interseismic creep but failed to reach the surface; (3) that aseismic afterslip occurred around the area that ruptured seismically. We find consistency between geodetic and seismological constraints on the partitioning between seismic and aseismic creep. About 80-90% of slip on the LVF in the 0-26 km seismogenic depth range is actually aseismic. We infer that the clay-rich Lichi melange is the key factor promoting aseismic creep at shallow depth.

  19. Methodology for the interpretation of fault-slip seismicity in a weak shear zone

    NASA Astrophysics Data System (ADS)

    Sainoki, Atsushi; Mitri, Hani S.

    2014-11-01

    Fault-slip related seismic events that occur in underground mines could inflict severe damage to underground openings; thus a proper estimation of fault-slip potential in active mining areas is of paramount importance in assessing its risk. It is not uncommon in underground mines that large seismic events take place away from stopes being extracted, where fault-slip potential is presumed not to be high enough to result in those seismic events. In the present paper, fault-slip related seismic events taking place within a weak shear zone in Garson Mine, Sudbury, Canada are investigated. First, in order to understand the stress states of rockmass in the mine, numerical analysis is carried out with a 3D mine-wide model whilst assuming isotropic elasticity. The result obtained from the analysis reveals that the shear stress of rockmass in a weak shear zone does not reach the maximum shear strength determined by Mohr-Coulomb failure criterion with basic friction angles of the rockmass. The result contradicts a fact that quite a few seismic events have been actually recorded in the regions with micro seismic monitoring systems installed in the mine. As an interpretation of that, it is postulated that variations in shear stiffness within the shear zone contribute to the generation of high slip potential resulting in the occurrence of those seismic events. In order to justify the postulation, numerical analysis is additionally carried out, in which the shear zone is modelled with transversely isotropic models, of which shear stiffness is decreased in the same direction as a measured joint orientation in the shear zone. For source regions of those seismic events, isotropic models are used without decreasing its shear stiffness, thus resulting in the discrepancy in shear stiffness between the source regions and other areas in the shear zone. The result obtained from the analysis verifies that fault-slip potential drastically increases within the source regions due to the difference in shear stiffness. It is further found out from dynamic analysis in which fault-slip is simulated with Barton's shear strength model that the increasing slip potential is high enough to cause large seismic events in the regions. In the present study, the interpretation of seismic events occurring within a weak shear zone is provided, and a methodology to simulate high fault-slip potential that could be generated within the shear zone is developed. The methodology can be used with back analysis to determine the mechanical properties of the weak shear zone, which lead to the better estimation of fault-slip potential.

  20. Electrostatic precursors to granular slip events.

    PubMed

    Shinbrot, Troy; Kim, Nam H; Thyagu, N Nirmal

    2012-07-01

    It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials. PMID:22689956

  1. Electrostatic precursors to granular slip events

    PubMed Central

    Shinbrot, Troy; Kim, Nam H.; Thyagu, N. Nirmal

    2012-01-01

    It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials. PMID:22689956

  2. Slow slip event at Kilauea Volcano

    USGS Publications Warehouse

    Poland, Michael P.; Miklius, Asta; Wilson, J. David; Okubo, Paul G.; Montgomery-Brown, Emily; Segall, Paul; Brooks, Benjamin; Foster, James; Wolfe, Cecily; Syracuse, Ellen; Thurbe, Clifford

    2010-01-01

    Early in the morning of 1 February 2010 (UTC; early afternoon 31 January 2010 local time), continuous Global Positioning System (GPS) and tilt instruments detected a slow slip event (SSE) on the south flank of Kilauea volcano, Hawaii. The SSE lasted at least 36 hours and resulted in a maximum of about 3 centimeters of seaward displacement. About 10 hours after the start of the slip, a flurry of small earthquakes began (Figure 1) in an area of the south flank recognized as having been seismically active during past SSEs [Wolfe et al., 2007], suggesting that the February earthquakes were triggered by stress associated with slip [Segall et al., 2006].

  3. Dynamical stability of slip-stacking particles

    NASA Astrophysics Data System (ADS)

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-01

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  4. Frictional constitutive law at intermediate slip rates accounting for flash heating and thermally activated slip process

    Microsoft Academic Search

    Hiroyuki Noda

    2008-01-01

    A constitutive law in a rate- and state-dependent framework accounting for flash heating at microscopic contacts is proposed on the basis of a simple asperity model and a thermally activated slip process thought to cause logarithmic dependency of the friction coefficient on slip rate. This law is probably applicable in an intermediate slip rate regime (about 0.001–0.1 m\\/s), where contact

  5. Slip-Mediated Dewetting of Polymer Microdroplets

    E-print Network

    Joshua D. McGraw; Tak Shing Chan; Simon Maurer; Thomas Salez; Michael Benzaquen; Élie Raphaël; Martin Brinkmann; Karin Jacobs

    2015-07-13

    Classical models for wetting predict that an infinite work is required to move a three-phase contact line, defined as the line where a liquid-vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap shaped polystyrene microdroplets, with non-equilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using \\textit{in situ} atomic force microscopy, and the results are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. We find that slip has a strong influence on the droplet evolutions, both on the transient non-spherical shapes and contact line dynamics.

  6. Slip-Mediated Dewetting of Polymer Microdroplets

    E-print Network

    McGraw, Joshua D; Maurer, Simon; Salez, Thomas; Benzaquen, Michael; Raphaël, Élie; Brinkmann, Martin; Jacobs, Karin

    2015-01-01

    Classical models for wetting predict that an infinite work is required to move a three-phase contact line, defined as the line where a liquid-vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap shaped polystyrene microdroplets, with non-equilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using \\textit{in situ} atomic force microscopy, and the results are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. We find that slip has a strong influence on the droplet evolutions, both on the transient non-spherical shapes and contact line dynamics.

  7. Effects of interlayer slip on multilayered folds

    E-print Network

    Casarta, Lawrence Joseph

    1980-01-01

    , features develop that indicate interlayer slip has occurred. These features include: (1) slickensides oriented parallel to layering and perpendicular to fold axis, (Z) flowage of intervening more ductile rocks parallel to layering and perpendicular...

  8. Subgrain boundaries and slip systems in quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger

    2015-04-01

    At elevated temperatures, quartz usually deforms by dislocation glide and dislocation creep. Textures (crystallographic preferred orientations) and microstructures are commonly used to infer the kinematics and physical conditions of deformation. However, it is debatable whether a given texture, represented by a pole figure, is universally indicative of a specific deformation temperature or recrystallization mechanism or e.g. is rather related to strain. Quartz veins in synkinematic, felsic dikes from the footwall of the Mohave Wash detachment fault in the Chemehuevi Mountains are studied by EBSD, CIP and universal stage. Mm-sized quartz grains are homogeneously stretched with aspect ratios of up to 30. Minor recrystallization takes place by subgrain rotation. Three different groups of highly stretched quartz grains can be defined: Grains with peripheral c-axes at a high angle to the foliation (Z-grains), grains with central c-axes perpendicular to the lineation (Y-grains) and grains with c-axes intermediately between the former two (O-grains). The three types of grains do not show a significant difference in their aspect ratios. Bulk pole figures show a kinked single c-axes girdle with a central maximum and an a-axes maximum parallel to the lineation. Misorientation analysis and the orientation of subgrain boundaries are used to make inferences on slip systems. Z-grains are interpreted to be suitable for basal (c)-slip, Y-grains for prism {m}-slip, which is compatible with the bulk misorientation distribution function of entire grains. O-grains could be interpreted as suitably oriented for rhomb {r/z/pi/pi'} slip, however, this is not supported by the bulk misorientation distribution function. Individual subgrain boundaries in Y-grains and Z-grains expected for the 'easy' slip systems {m} and (c) with tilt character ({a} parallel boundaries with [c] or misorientation axes, respectively), are limited to small (< 2°) misorientation angles. Subgrain boundaries with higher misorientation angles relate to variable slip systems, showing tilt, twist or mixed mode character. Many of those slip systems have a low Schmid factor. O-grains rarely show subgrain boundaries that can directly be related to rhomb or rhomb-slip. Most common subgrain boundaries are tilt {a}[c]-boundaries, tilt {a}-boundaries or mixed mode boundaries, hence deformation is interpreted to occur mostly by combined {m} and (c)-slip rather than rhomb slip. Based on the homogeneous microstructure without a low temperature overprint, it is inferred that deformation took place in a rather narrow temperature range. Grains deform homogeneously, independent on their orientation with different slip systems involved. A temperature effect on the activity of individual slip system is not recognizable. Suitably oriented (c) and {m} slip systems seem to result in lattice bending rather than abundant subgrain boundaries. Subgrain boundaries related to other slip systems contribute to subgrain rotation and subsequent recrystallization but not essentially to stretching of grains and rather ensure strain compatibility. The observations indicate that many prominent subgrain boundaries might not relate to the main strain producing slip system and grain orientation does not necessarily prescribe the involved slip systems.

  9. Coseismic Dip Slip Distribution of the 1 Apr 2007 Solomon Islands Mw8.1 Earthquake from a Fully Bayesian Inversion

    NASA Astrophysics Data System (ADS)

    Chen, T.

    2009-12-01

    102 uplift and subsidence measurements over the southeastern end of the rupture zone from two field surveys shortly after 1 Apr 2007 Solomon Islands Earthquake provide a unique geodetic constraint in the following inversion of distributed slip. In the conventional inversion of geodetic data for spatial distribution of fault slip the solution is maintained by minimizing the second-order spatial derivative of slip and the smoothing parameter is often selected subjectively at the bend of the trade-off curve of misfit as a function of slip roughness. A fully Bayesian slip inversion method[Fukuda et al.,2008] is used to overcome the deficiency of selecting the smoothing parameter subjectively. The smoothing parameter is estimated with the distributed slip at the same time under a unified theoretical Bayesian framework. The joint posterior probability density function of distributed slip and smoothing parameter is formulated using Bayes’ theorem and sampled with Markov chain Monte Carlo method. I will apply this method to coseismic slip distribution associated with the 2007 Mw8.1 Solomon Islands earthquake and compare the results of this method with conventional method and the coseismic finite fault model of Furlong et al.[2009].

  10. A Bayesian inversion for slip distribution of 1 Apr 2007 Mw8.1 Solomon Islands Earthquake

    NASA Astrophysics Data System (ADS)

    Chen, T.; Luo, H.

    2013-12-01

    On 1 Apr 2007 the megathrust Mw8.1 Solomon Islands earthquake occurred in the southeast pacific along the New Britain subduction zone. 102 vertical displacement measurements over the southeastern end of the rupture zone from two field surveys after this event provide a unique constraint for slip distribution inversion. In conventional inversion method (such as bounded variable least squares) the smoothing parameter that determines the relative weight placed on fitting the data versus smoothing the slip distribution is often subjectively selected at the bend of the trade-off curve. Here a fully probabilistic inversion method[Fukuda,2008] is applied to estimate distributed slip and smoothing parameter objectively. The joint posterior probability density function of distributed slip and the smoothing parameter is formulated under a Bayesian framework and sampled with Markov chain Monte Carlo method. We estimate the spatial distribution of dip slip associated with the 1 Apr 2007 Solomon Islands earthquake with this method. Early results show a shallower dip angle than previous study and highly variable dip slip both along-strike and down-dip.

  11. A new automated cycle slip detection and repair method for a single dual-frequency GPS receiver

    NASA Astrophysics Data System (ADS)

    Liu, Zhizhao

    2011-03-01

    This paper develops a new automated cycle slip detection and repair method that is based on only one single dual-frequency GPS receiver. This method jointly uses the ionospheric total electron contents (TEC) rate (TECR) and Melbourne-Wübbena wide lane (MWWL) linear combination to uniquely determine the cycle slip on both L1 and L2 frequencies. The cycle slips are inferred from the information of ionospheric physical TECR and MWWL ambiguity at the current epoch and that at the previous epoch. The principle of this method is that when there are cycle slips, the MWWL ambiguity will change and the ionospheric TECR will usually be significantly amplified, the part of artificial TECR (caused by cycle slips) being significantly larger than the normal physical TECR. The TECR is calculated based on the dual-frequency carrier phase measurements, and it is highly accurate. We calculate the ionospheric change information (including TECR and TEC acceleration) using the previous epochs (30 epochs in this study) and use the previous data to predict the TECR for the epoch needing cycle slip detection. If the discrepancy is larger than our defined threshold 0.15 TECU/s, cycle slips are regarded to exist at that epoch. The key rational of method is that during a short period (1.0 s in this study) the TECR of physical ionospheric phenomenon will not exceed the threshold. This new algorithm is tested with eight different datasets (including one spaceborne GPS dataset), and the results show that the method can detect and correctly repair almost any cycle slips even under very high level of ionospheric activities (with an average Kp index 7.6 on 31 March 2001). The only exception of a few detected but incorrectly repaired cycle slip is due to a sudden increased pseudorange error on a single satellite (PRN7) under very active ionosphere on 31 March 2001. This method requires dual-frequency carrier phase and pseudorange data from only one single GPS receiver. The other requirement is that the GPS data rate ideally is 1 Hz or higher in order to detect small cycle slips. It is suitable for many applications where one single receiver is used, e.g. real-time kinematic rover station and precise point positioning. An important feature of this method is that it performs cycle slip detection and repair on a satellite-by-satellite basis; thus, the cycle slip detection and repair for each satellite are completely independent and not affected by the data of other satellites.

  12. Fault zone structure and seismic slip localization in dolostones, an example from the Southern Alps, Italy

    NASA Astrophysics Data System (ADS)

    Fondriest, Michele; Smith, Steven A. F.; Di Toro, Giulio; Zampieri, Dario; Mittempergher, Silvia

    2012-12-01

    Fault zones cutting limestones and dolostones represent significant seismogenic sources worldwide. The structure of an exhumed strike-slip fault zone hosted in dolostones, the Borcola Pass Fault Zone (BPFZ, Italian Southern Alps), was studied by means of field and microstructural analysis. Ambient conditions of faulting were ca. 1.6-1.7 km and 50 °C. The BPFZ consists of a >80 m wide damage zone cut by three systems of sub-vertical secondary faults striking approximately N-S, E-W and NW-SE. N-S and E-W striking faults reactivated pre-existing Jurassic-Paleogene joints with spacing between 0.2 and 0.5 m, whereas NW-SE striking faults were newly formed during post-Paleogene activity associated with movements along the nearby Schio-Vicenza Line. The core of the BPFZ consists of dolostone fault rock lenses bound by slip zones up to 10 cm thick. Both the principal and secondary slip zones consist of cement-supported dolomitic cataclasites and dolomite-filled veins. Some slip zones contain a sub-centimeter thick “vein-like” cataclastic layer (Layer-A) located immediately beneath the slip surface that truncates another cataclasite below (Layer-B). Detailed microstructural and clast size distribution analysis suggests that Layer-A experienced fluidization (cuspate-lobate boundaries, injection structures, strong grain sorting: D < 1 for clast diameters smaller than 300 ?m) possibly related to fast fault slip following seismic ruptures. In light of these observations a conceptual model is proposed for the formation of Layer-A, and the structure of the BPFZ is compared to that of an active seismogenic fault cutting carbonates.

  13. The prevention of slipping accidents: a review and discussion of work related to the methodology of measuring slip resistance

    Microsoft Academic Search

    S. Leclercq

    1999-01-01

    The recommendations made after the analysis of accidents following an incident of slipping often include the use of anti-slip footwear and\\/or the installation of an anti-slip floor covering. Such recommendations make it necessary to study biomechanical and tribologic phenomena that occur during slipping, in particular in order to develop criteria for the evaluation of the slip resistance of footwear and

  14. Cyclic deformation response of planar-slip materials and a new criterion for the wavy-to-planar-slip transition

    Microsoft Academic Search

    Zhirui Wang

    2004-01-01

    This paper will start with the review of mechanical response and dislocation structure evolution of single crystals of planar-slip alloys during cyclic deformation. Experimental results with typical planar-slip materials have demonstrated that, unlike typical wavy-slip crystals, planar-slip materials do not exhibit 'real' cyclic saturation behaviour, nor is there any evidence for the formation of persistent slip bands and dislocation ladder

  15. Smoothing and roughening of slip surfaces in direct shear experiments

    NASA Astrophysics Data System (ADS)

    Sagy, Amir; Badt, Nir; Hatzor, Yossef H.

    2015-04-01

    Faults in the upper crust contain discrete slip surfaces which have absorbed a significant part of the shear displacement along them. Field measurements demonstrate that these surfaces are rough at all measurable scales and indicate that surfaces of relatively large-slip faults are statistically smoother than those of small-slip faults. However, post faulting and surface erosion process that might affect the geometry of outcrops cannot be discounted in such measurements. Here we present experimental results for the evolution of shear surface topography as function of slip distance and normal stress in direct shear experiments. A single prismatic fine grain limestone block is first fractured in tension mode using the four-point bending test methodology and then the fracture surface topography is scanned using a laser profilometer. We then shear the obtained tensile fracture surfaces in direct shear, ensuring the original fracture surfaces are in a perfectly matching configuration at the beginning of the shear test. First, shearing is conducted to distances varying from 5 to 15 mm under constant normal stress of 2MPa and a constant displacement rate of 0.05 mm/s using two closed-loop servo controlled hydraulic pistons, supplying normal and shear forces (Davidesko et al., 2014). In the tested configuration peak shear stress is typically attained after a shear displacement of about 2-3 mm, beyond which lower shear stress is required to continue shearing at the preset displacement rate of 0.05 mm/s as is typical for initially rough joints. Following some initial compression the interface begins to dilate and continues to do so until the end of the test. The sheared tensile fracture surface is then scanned again and the geometrical evolution, in term of RMS roughness and power spectral density (PSD) is analyzed. We show that shearing smooth the surface along all our measurements scales. The roughness ratio, measured by initial PSD / final PSD for each wavelength, increases as a function of slip amount. The roughness measured after slip can be fitted by a power-law similar to that of the initial tensile surface. In the next series of experiments a similar procedure is applied when the roughness evolution is measured as a function of increasing normal stress for a fixed displacement amount of 10 mm. While samples sheared under a constant normal stress of 5 MPa generated surface smoothing, shearing under normal stress of 7.5 MPa to 15 MPa exhibited surface roughening at the measured range of scales. We find that roughening is correlated with the attained peak shear stress values, stress drop (peak shear stress minus residual shear stress) and with wear accumulation, a novel measurement procedure of which is developed here. Analysis of the sheared samples shows that roughening is generated by sets of dense fractures that significantly damaged the sample in the immediate proximity to large asperities. This roughening is related to penetrative damage during transient wear in rough surfaces.

  16. A unit for electrohydraulic impulse expansion of tubes in tube walls

    Microsoft Academic Search

    B. Ya. Mazurovskii; Zh. N. Ishchenko; B. Ya. Konvisher

    1977-01-01

    mer, a rectifier, a battery of condensers, and a commutating unit. The production section is designed for moving the electrode in the plane of the tube wall and supplying power to the working tools, one-time use chucks (Fig. 3), which had already been placed in the ends of the tubes. The operation of the unit is controlled from the remote-control

  17. Prediction of slips: an evaluation of utilized coefficient of friction and available slip resistance

    Microsoft Academic Search

    J. M. Burnfield; C. M. Powers

    2006-01-01

    The purpose of this study was to investigate the relationship between measures of floor surface slip resistance and an individual's peak utilized coefficient of friction (COFU) on the probability of a slip occurring during level walking. Video, kinematic and ground reaction force data were recorded simultaneously as subjects walked at a self-selected speed during conditions of normal and reduced floor

  18. Constraining Paleoearthquake Slip Distributions with Coral Microatolls

    NASA Astrophysics Data System (ADS)

    Lindsay, A.; McCloskey, J.; nic Bhloscaidh, M.; Murphy, S.

    2014-12-01

    Key to understanding the threat posed by large megathrust earthquakes is identifying where the potential for these destructive events exists. Studying extended sequences of earthquakes, Slip Deficit and Stress Evolution modelling techniques may hold the key to locating areas of concern. However, as well as using recent instrumentally constrained slip distributions they require the production of high resolution source models for pre-instrumental events. One place we can attempt this longer term modelling is along the Sunda Trench with its record of large megathrust earthquakes dating back centuries. Coral microatolls populating the intertidal areas of the Sumatran Forearc act as long-term geodetic recorders of tectonic activity. Repeated cycles of stress accumulation and release alter relative sea levels around these islands. Growth of corals, controlled by the level of the lowest tide, exploit interseismic rises in sea level. In turn, they experience die-offs when coseismic drops in sea level lead to subaerially exposure. Examination of coral stratigraphy reveals a history of displacements from which information of past earthquakes can be inferred. We have developed a Genetic Algorithm Slip Estimator (GASE) to rapidly produce high resolution slip distributions from coral displacement data. GASE recombines information held in populations of randomly generated slip distributions, to create superior models, satisfying observed displacements. Non-unique solutions require multiple iterations of the algorithm, producing a suite of models from which an ensemble slip distribution is drawn. Systematic testing of the algorithm demonstrates its ability to reliably estimate both known synthetic and instrumentally constrained slip distributions based on surface displacements. We will present high-resolution source models satisfying published displacement data for a number recent and paleoearthquakes along the Sunda trench, including the great 1797 and 1833 events.

  19. Evidence for slip partitioning and bimodal slip behavior on a single fault: Surface slip characteristics of the 2013 Mw7.7 Balochistan, Pakistan earthquake

    NASA Astrophysics Data System (ADS)

    Barnhart, W. D.; Briggs, R. W.; Reitman, N. G.; Gold, R. D.; Hayes, G. P.

    2015-06-01

    Deformation is commonly accommodated by strain partitioning on multiple, independent strike-slip and dip-slip faults in continental settings of oblique plate convergence. As a corollary, individual faults tend to exhibit one sense of slip - normal, reverse, or strike-slip - until whole-scale changes in boundary conditions reactivate preexisting faults in a new deformation regime. In this study, we show that a single continental fault may instead partition oblique strain by alternatively slipping in a strike-slip or a dip-slip sense during independent fault slip events. We use 0.5 m resolution optical imagery and sub-pixel correlation analysis of the 200 + km 2013 Mw7.7 Balochistan, Pakistan earthquake to document co-seismic surface slip characteristics and Quaternary tectonic geomorphology along the causative Hoshab fault. We find that the 2013 earthquake, which involved a ?6:1 strike-slip to dip-slip ratio, ruptured a structurally segmented fault. Quaternary geomorphic indicators of gross fault-zone morphology reveal both reverse-slip and strike-slip deformation in the rupture area of the 2013 earthquake that varies systematically along fault strike despite nearly pure strike-slip motion in 2013. Observations of along-strike variations in range front relief and geomorphic offsets suggest that the Hoshab fault accommodates a substantial reverse component of fault slip in the Quaternary, especially along the southern section of the 2013 rupture. We surmise that Quaternary bimodal slip along the Hoshab fault is promoted by a combination of the arcuate geometry of the Hoshab fault, the frictional weakness of the Makran accretionary prism, and time variable loading conditions from adjacent earthquakes and plate interactions.

  20. Inertial Aided Cycle Slip Detection and Identification for Integrated PPP GPS and INS

    PubMed Central

    Du, Shuang; Gao, Yang

    2012-01-01

    The recently developed integrated Precise Point Positioning (PPP) GPS/INS system can be useful to many applications, such as UAV navigation systems, land vehicle/machine automation and mobile mapping systems. Since carrier phase measurements are the primary observables in PPP GPS, cycle slips, which often occur due to high dynamics, signal obstructions and low satellite elevation, must be detected and repaired in order to ensure the navigation performance. In this research, a new algorithm of cycle slip detection and identification has been developed. With the aiding from INS, the proposed method jointly uses WL and EWL phase combinations to uniquely determine cycle slips in the L1 and L2 frequencies. To verify the efficiency of the algorithm, both tactical-grade and consumer-grade IMUs are tested by using a real dataset collected from two field tests. The results indicate that the proposed algorithm can efficiently detect and identify the cycle slips and subsequently improve the navigation performance of the integrated system. PMID:23202164

  1. Inertial aided cycle slip detection and identification for integrated PPP GPS and INS.

    PubMed

    Du, Shuang; Gao, Yang

    2012-01-01

    The recently developed integrated Precise Point Positioning (PPP) GPS/INS system can be useful to many applications, such as UAV navigation systems, land vehicle/machine automation and mobile mapping systems. Since carrier phase measurements are the primary observables in PPP GPS, cycle slips, which often occur due to high dynamics, signal obstructions and low satellite elevation, must be detected and repaired in order to ensure the navigation performance. In this research, a new algorithm of cycle slip detection and identification has been developed. With the aiding from INS, the proposed method jointly uses WL and EWL phase combinations to uniquely determine cycle slips in the L1 and L2 frequencies. To verify the efficiency of the algorithm, both tactical-grade and consumer-grade IMUs are tested by using a real dataset collected from two field tests. The results indicate that the proposed algorithm can efficiently detect and identify the cycle slips and subsequently improve the navigation performance of the integrated system. PMID:23202164

  2. Asymmetrical slip propensity: required coefficient of friction

    PubMed Central

    2013-01-01

    Background Most studies in performing slips and falls research reported their results after the ipsilateral leg of subjects (either right foot or left foot) was guided to contact the contaminated floor surface although many studies indicated concerns for asymmetries of legs in kinematic or kinetic variables. Thus, the present study evaluated if dominant leg’s slip tendency would be different from non-dominant leg’s slip tendency by comparing the Required Coefficient of Friction (RCOF) of the two lower limbs. Findings Forty seven health adults participated in the present study. RCOF was measured when left or right foot of subjects contacted the force platforms respectively. Paired t-test was performed to test if RCOF and heel velocity (HCV) of dominant legs was different from that of non-dominant legs. It was suggested that the asymmetry in RCOFs and HCV between the two lower limbs existed. The RCOFs of non-dominant legs were higher than that of dominant legs. Conclusions The results indicated that asymmetry in slip propensity, RCOF, was existed in lower extremity. The results from the study suggested that it would be benefit to include a variable, such as asymmetry, in slips and falls research. PMID:23902896

  3. Active and recent strike-slip tectonics

    NASA Astrophysics Data System (ADS)

    Nur, Amos; Boccaletti, Mario

    An international workshop cosponsored by the Department of Geology, University of Florence, Italy and the Department of Geophysics, Stanford University, Stanford, Calif., was held in Florence, Italy, April 18-20, 1989,on the topic of active and recent strike-slip tectonics in the continental crust. Workshop participants from Turkey, Ethiopia, Israel, Greece, and various universities in Italy, Spain, West Germany, France, the United Kingdom, Brazil, and the United States reported on a broad range of studies involving strike-slip faulting in continental crustal setting. As it turned out, much of the work reported on involved aspects of strike-slip faulting that are only poorly understood, especially crustal deformation, which is distributed over a multiplicity of faults, or even fault domains.One of the rewarding aspects of this workshop was the diversity of geographic areas and geological settings covered by the reporters. The north and east Anatolian faults, the Dead Sea transform zone, western Turkey, north and central Greece, Malta, Sicily, southern Italy, the bethic Cordillera in southern Spain, Tunisia, Tibet and southwest China, offshore Brazil, Alaska, Nevada, and California. A recurring observation reported for all those areas was mixed mode faulting, i.e., the coterminous or sequential occurrence of strike-slip and normal faulting, or strike-slip and thrust, and in many instances also strikeslip, normal and thrust faulting in a single tectonic setting.

  4. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    NASA Astrophysics Data System (ADS)

    Rizza, M.; Ritz, J.-F.; Braucher, R.; Vassallo, R.; Prentice, C.; Mahan, S.; McGill, S.; Chauvet, A.; Marco, S.; Todbileg, M.; Demberel, S.; Bourlès, D.

    2011-09-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is ˜1 mm yr-1 along the WIB and EIB segments and ˜0.5 mm yr-1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78-7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of ˜2500-5200 yr for past earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a 'characteristic earthquake' mode.

  5. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    USGS Publications Warehouse

    Prentice, Carol S.; Rizza, M.; Ritz, J.F.; Baucher, R.; Vassallo, R.; Mahan, S.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into ?ve main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is?1 mm yr–1 along the WIB and EIB segments and?0.5 mm yr–1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, re?ecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78–7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of?2500–5200 yr for past earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a ‘characteristic earthquake’ mode.

  6. A STUDY ON HIGH STRENGTH BOLTED JOINT WITH METAL-SPRAYED CONTACT SURFACES

    NASA Astrophysics Data System (ADS)

    Minami, Kuniaki; Saito, Masamichi; Yokoyama, Hideki; Sugimoto, Ichiro; Nojima, Takao; Masunaga, Toshihiko; Nagasaki, Eiji

    Slip coefficient of high-strength bolt friction joints is well known to depend on the condition of contact surfaces. The coefficient is determined as 0.4 in the Specifications for Highway Bridges and the Design Standards for Railway Structures and Commentary (Steel Structures) in Japan, in the condition of roughened contact surfaces with mill scale removed or painted contact surfaces with inorganic zinc rich paint. However, the slip coefficient with metal-sprayed surfaces is not clear. For the joints with metalsprayed surfaces, hot-dip galvanized bolts are applied and such bolts are tightened by turn-of-nut method. However, it is unclear how much axial force is induced into the bolts in the joints with metal-sprayed surfaces. In order to examine slip coefficient of the bolted joints with metal-sprayed contact surfaces slip tests of high strength bolted joints were carried out. On the basis of above examinations, the slip coefficient with metal-sprayed surfaces is proposed in this paper. To clarify the induced axial force of the bolts, bolt-tightening tests were carried out. Considering bolt diameter, bolt length, induced axial forces and their relaxation, nut rotation angles are proposed in relation to different bolt size.

  7. Slip effects in dewetting polymer microdroplets

    NASA Astrophysics Data System (ADS)

    McGraw, Joshua D.; Salez, Thomas; Maurer, Simon; Chan, Tak Shing; Benzaquen, Michael; Brinkmann, Martin; Raphaël, Élie; Jacobs, Karin

    2014-03-01

    Spherical caps on a substrate with less than equilibrium contact angles contract as a result of capillary forces. Applying the classical no-slip condition at the liquid-substrate interface results in diverging stress at the contact line. This divergence can be alleviated, however, by allowing finite flow velocity at the substrate, corresponding to the slip boundary condition. Experiments have been conducted in which glassy polystyrene microdroplets are placed upon, as substrates, different self-assembled monolayers (SAMs). The spherical caps are prepared such that initial contact angles are much less than the equilibrium contact angle. Above the glass transition temperature, a capillary induced flow is observed; the droplet radii shrink while their heights grow. Furthermore, the intermediate height profiles are highly non-spherical. Different SAMs give rise to differing slip lengths, resulting in dramatic changes to the temporal and morphological path these tiny droplets take toward their equilibrium spherical cap shapes.

  8. Quake clamps down on slow slip

    NASA Astrophysics Data System (ADS)

    Wallace, Laura M.; Bartlow, Noel; Hamling, Ian; Fry, Bill

    2014-12-01

    Using continuous GPS (cGPS) data from the Hikurangi subduction zone in New Zealand, we show for the first time that stress changes induced by a local earthquake can arrest an ongoing slow slip event (SSE). The cGPS data show that the slip rate in the northern portion of the 2013/2014 Kapiti SSE decreased abruptly following a nearby intraslab earthquake. We suggest that deceleration of the Kapiti SSE in early 2014 occurred due to a tenfold increase in the normal stress relative to shear stress in the SSE source, induced by the nearby Mw 6.3 earthquake, consistent with expectations of rate and state friction. Our observation of an abrupt halting/slowing of the SSE in response to stress changes imposed by a local earthquake has implications for the strength of fault zones hosting SSEs and supports the premise that static stress changes are an important ingredient in triggering (or delaying) fault slip.

  9. Fault slip distribution of the 2014 Iquique, Chile, earthquake estimated from ocean-wide tsunami waveforms and GPS data

    NASA Astrophysics Data System (ADS)

    Gusman, Aditya Riadi; Murotani, Satoko; Satake, Kenji; Heidarzadeh, Mohammad; Gunawan, Endra; Watada, Shingo; Schurr, Bernd

    2015-02-01

    We applied a new method to compute tsunami Green's functions for slip inversion of the 1 April 2014 Iquique earthquake using both near-field and far-field tsunami waveforms. Inclusion of the effects of the elastic loading of seafloor, compressibility of seawater, and the geopotential variation in the computed Green's functions reproduced the tsunami traveltime delay relative to long-wave simulation and allowed us to use far-field records in tsunami waveform inversion. Multiple time window inversion was applied to tsunami waveforms iteratively until the result resembles the stable moment rate function from teleseismic inversion. We also used GPS data for a joint inversion of tsunami waveforms and coseismic crustal deformation. The major slip region with a size of 100 km × 40 km is located downdip the epicenter at depth ~28 km, regardless of assumed rupture velocities. The total seismic moment estimated from the slip distribution is 1.24 × 1021 N m (Mw 8.0).

  10. Asymmetric alluvial fans along strike-slip faults: A potential slip-rate record?

    NASA Astrophysics Data System (ADS)

    Morelan, A. E., III; Oskin, M. E.

    2014-12-01

    We investigate the phenomenon of asymmetric alluvial fan morphology along strike-slip faults. From analysis of high-resolution topographic data, we find that asymmetric alluvial fans are common along several strike-slip faults in the western United States. Affected fans are steeper in the direction of translation of the sediment source, often resulting in stream deflections counter to that expected from the sense of fault slip (e.g. left deflected streams along dextral faults). We hypothesize that fan asymmetry results from lateral translation of the sediment source relative to the depocenter. This relative motion changes the accommodation space in such a way that one side of the alluvial fan continuously progrades while the other is gradually abandoned. Therefore, lateral translation results in radial asymmetry of slopes about the fan apex. As a first approximation, we model this asymmetry as a result of diffusive sediment transport down fan. From this analysis, we predict that the degree of asymmetry of the alluvial fan is controlled by the ratio of sediment flux to fault slip rate. Qualitatively, more rapidly slipping faults should host more highly asymmetric fans; conversely, high sediment flux will obscure asymmetry. By measuring the sediment flux, through catchment-average concentration of cosmogenic isotopes or other means, we show that it is theoretically possible to quantify strike-slip fault slip-rates and alluvial-fan sediment transport rates using alluvial fan morphometry.

  11. Slipping magnetic reconnection in coronal loops.

    PubMed

    Aulanier, Guillaume; Golub, Leon; Deluca, Edward E; Cirtain, Jonathan W; Kano, Ryouhei; Lundquist, Loraine L; Narukage, Noriyuki; Sakao, Taro; Weber, Mark A

    2007-12-01

    Magnetic reconnection of solar coronal loops is the main process that causes solar flares and possibly coronal heating. In the standard model, magnetic field lines break and reconnect instantaneously at places where the field mapping is discontinuous. However, another mode may operate where the magnetic field mapping is continuous but shows steep gradients: The field lines may slip across each other. Soft x-ray observations of fast bidirectional motions of coronal loops, observed by the Hinode spacecraft, support the existence of this slipping magnetic reconnection regime in the Sun's corona. This basic process should be considered when interpreting reconnection, both on the Sun and in laboratory-based plasma experiments. PMID:18063789

  12. Momentum compaction and phase slip factor

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.3.11 of the Handbook of Accelerator Physics and Engineering on Landau damping is updated. The slip factor and its higher orders are given in terms of the various orders of the momentum compaction. With the aid of a simplified FODO lattice, formulas are given for the alteration of the lower orders of the momentum compaction by various higher multipole magnets. The transition to isochronicity is next demonstrated. Formulas are given for the extraction of the first three orders of the slip factor from the measurement of the synchrotron tune while changing the rf frequency. Finally bunch-length compression experiments in semi-isochronous rings are reported.

  13. The mechanics of stick-slip

    USGS Publications Warehouse

    Byerlee, J.D.

    1970-01-01

    Physical mechanisms that have been proposed to explain the occurrence of stick-slip motion during frictional sliding have been examined in the light of results obtained from experiments with rocks and brittle minerals. An instability caused by sudden brittle fracture of locked regions on surfaces in contact is the most likely explanation for stick-slip during dry frictional sliding of brittle rocks at room temperature. Areas requiring further study and the uncertainties in applying the results of laboratory experiments to earthquake studies are emphasized. ?? 1970.

  14. Statistical Analysis of the Surface Slip Profiles and Slip Models for the 2008 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Lavallee, D.; Shao, G.; Ji, C.

    2009-12-01

    The 2008 Wenchuan earthquake provides a remarkable opportunity to study the statistical properties of slip profiles recorded at the surface. During the M 8 Wenchuan earthquake, the surface ruptured over 300 km along the Longmenshan fault system. The surface slip profiles have been measured along the fault for a distance of the order of 270 km without any significant change in the strike direction. Field investigations suggest that the earthquake generated a 240 km surface rupture along the Beichuan segment and 72 km surface rupture along the Guanxian segment. Maximum vertical and horizontal slip of 10 m and 4.9 m have been observed along the Beichuan fault. Measurements include the displacement parallel and perpendicular to the fault as well as the width of the rupture zone. However, the recorded earthquake slip profiles are irregularly sampled. Traditional algorithms used to compute the discrete Fourier transform are developed for data sampled at regularly spaced intervals. It should be noted that interpolating the slip profile over a regular grid is not appropriate when investigating the spectrum functional behavior or when computing the discrete Fourier transform. Interpolation introduces bias in the estimation of the Fourier transform that adds artificial correlation to the original data. To avoid this problem, we developed an algorithm to compute the Fourier transform of irregularly sampled data. It consists essentially in determining the coefficients that best fit the data to the Sine and Cosine functions at a given wave number. We compute the power spectrum of the slip profiles of the Wenchuan earthquakes. In addition, we also compute the power spectrum for the slip inversions computed for the Wenchuan earthquakes. To model the functional behavior of the spectrum curves, we consider two functions: the power law function and the von Karman function. For all the slip models, we compute the parameters of the power law function and the von Karman function that best fit the spectrum curves. We also compute the probability density function of the slip profiles. The spectrum obtained for the surface slip profiles are compared to the spectrum computed for the slip profile recorded at the surface on the Arifiye segment of the North Anatolian Fault zone and a kinematic source inversion for the 1999 Izmit (Turkey) earthquake and the spectrum computed for the slip profile recorded during the 2001 Kunlunshan earthquake.

  15. Joint Projects / Joint Seminars October 2013

    E-print Network

    Fuchs, Clemens

    Joint Projects / Joint Seminars October 2013 Information Sheet Bilateral Programs (MoU) ­ Joint Projects (JP) / Joint Seminars (JS) FWF has signed bilateral agreements ­ so called "Memorandums of Understanding" (MoU) ­ with several international partner organisations. These agreements usually aim at jointly

  16. Development of compact slip detection sensor using dielectric elastomer

    NASA Astrophysics Data System (ADS)

    Choi, Jae-young; Hwang, Do-Yeon; Kim, Baek-chul; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Ja Choon

    2015-04-01

    In this paper, we developed a resistance tactile sensor that can detect a slip on the surface of sensor structure. The presented sensor device has fingerprint-like structures that are similar with the role of the humans finger print. The resistance slip sensor that the novel developed uses acrylo-nitrile butadiene rubber (NBR) as a dielectric substrate and graphene as an electrode material. We can measure the slip as the structure of sensor makes a deformation and it changes the resistance through forming a new conductive route. To manufacture our sensor, we developed a new imprint process. By using this process, we can produce sensor with micro unit structure. To verify effectiveness of the proposed slip detection, experiment using prototype of resistance slip sensor is conducted with an algorithm to detect slip and slip is successfully detected. We will discuss the slip detection properties.

  17. Geophys. J. Int. (2002) 150, 362376 Co-seismic slip from the 1995 July 30 Mw = 8.1 Antofagasta, Chile,

    E-print Network

    2002-01-01

    with seismic results. Predictions of the satellite LOS displacement from a seismic inversion and a joint, Chile, earthquake as constrained by InSAR and GPS observations M. E. Pritchard,1 M. Simons,1 P. A. Rosen.1 Antofagasta, Chile, earthquake and invert for the distribution of slip along the co-seismic fault plane. Using

  18. Slip casting and nitridation of silicon powder

    NASA Technical Reports Server (NTRS)

    Seiko, Y.

    1985-01-01

    Powdered Silicon was slip-cast with a CaSO4 x 0.5H2O mold and nitrided in a N atm. containing 0 or 5 vol. % H at 1000 to 1420 deg. To remove the castings, the modeling faces were coated successively with an aq. salt soap and powdered cellulose containing Na alginate, and thus prevented the sticking problem.

  19. Slip resistant properties of footwear on ice

    Microsoft Academic Search

    Chuansi Gao; John Abeysekera; Mikko Hirvonen; Raoul Grönqvist

    2004-01-01

    Current research on slipperiness of footwear has mainly focused on floors and lubricated floors. Slips and falls on icy and snowy surfaces involve not only outdoor workers, but also pedestrians and the general public; and occur in cold regions and in winter season in many parts of the world. However, in comparison with the size of the problem, research on

  20. Slip resistance testing of shoes — new developments

    Microsoft Academic Search

    P. J. PERKINS; M. P. WILSON

    1983-01-01

    This paper describes research being undertaken to develop a more realistic test for measuring the slip resistance of complete shoe soles and thus determine the effectiveness of sole patterns as well as sole materials and floor surfaces.The frictional forces between shoe and ground have been measured in normal walking using a force platform and photographic techniques used to record human

  1. The critical slip distance for seismic faulting

    NASA Astrophysics Data System (ADS)

    Scholz, C. H.

    1988-12-01

    Experimentally based friction laws1,2 have been found to predict virtually the entire range of observed behaviour of natural faults3,4. These laws contain a critical slip distance, L, which plays a key role in determining the degree of fault instability, the size of the zone of earthquake nucleation, the frictional breakdown width, and the proportion of pre- and post-seismic slip to co-seismic slip. In laboratory measurements L is found to be about 10-5m, but modelling results show that it must be about 10-2m if natural earthquake behaviour is to be simulated. The discovery that fault surfaces are fractal over the scale range 10-5-105 (refs 5,6), even for faults with large net slip, has confused the problem of scaling this parameter from laboratory experiments to natural faults, because fractal surfaces have no characteristic length. Here I show that geometrically unmated fractal surfaces, when in contact under a normal load, develop a characteristic length in their contact because long-wavelength apertures close under load whereas short-wavelength apertures may remain open. This critical distance may be identified with L, and calculations based on fault topography data show that at seismogenic depths it will be in the range anticipated from the earthquake modelling studies.

  2. Slip Dynamics in Small Scale Crystals

    NASA Astrophysics Data System (ADS)

    Maass, Robert; Derlet, Peter; Greer, Julia; Volkert, Cynthia

    2015-03-01

    Classical work showed that dislocation velocities are strongly dependent on applied stress. Numerous experiments have validated this for individual or groups of dislocations in macroscopic crystals by using imaging techniques combined with either mechanical data or time resolved topological data. Developments in small scale mechanical testing allow to correlate the intermittency of collective dislocation motion with the mechanical response. Discrete forward surges in displacement can be related to dislocation avalanches, which are triggered by the evolving dislocation sub-structure. We study the spatiotemporal characteristics of intermittent plastic flow in quasi-statically sheared single crystalline Au crystals with diameters between 300 nm and 10000 nm, whose displacement bursts were recorded at several kHz (Scripta Mater. 2013, 69, 586; Small, available online). Both the crystallographic slip magnitude, as well as the velocity of the slip events are exhibiting power-law scaling as. The obtained slip velocity distribution has a cubic decay at high values, and a saturated flat shoulder at lower velocities. No correlation between the slip velocity and the applied stress or plastic strain is found. Further, we present DD-simulations that are supportive of our experimental findings. The simulations suggest that the dynamics of the internal stress fields dominate the evolving dislocation structure leading to velocities that are insensitive to the applied stress - a regime indicative of microplasticity.

  3. Dynamics and wheel's slip ratio of a wheel-legged robot in wheeled motion considering the change of height

    NASA Astrophysics Data System (ADS)

    Ding, Xilun; Li, Kejia; Xu, Kun

    2012-09-01

    The existing research on dynamics and slip ratio of wheeled mobile robot (WMR) are derived without considering the effect of height, and the existing models can not be used to analyze the dynamics performance of the robot with variable height while moving such as NOROS-II. The existing method of dynamics modeling is improved by adding the constraint equation between perpendicular displacement of body and horizontal displacement of wheel into the constraint conditions. The dynamic model of NOROS-II in wheel motion is built by the Lagrange method under nonholonomic constraints. The inverse dynamics is calculated in three different paths based on this model, and the results demonstrate that torques of hip pitching joints are inversely proportional to the height of robot. The relative error of calculated torques is less than 2% compared with that of ADAMS simulation, by which the validity of dynamic model is verified. Moreover, the relative horizontal motion between fore/hind wheels and body is produced when the height is changed, and thus the accurate slip ratio can not be obtained by the traditional equation. The improved slip ratio equations with the parameter of the vertical velocity of body are introduced for fore wheels and hind wheels respectively. Numerical simulations of slip ratios are conducted to reveal the effect of varied height on slip ratios of different wheels. The result shows that the slip ratios of fore/hind wheels become larger/smaller respectively as the height increases, and as the height is reduced, the reverse applies. The proposed research of dynamic model and slip ratio based on the robot height provides the effective method to analyze the dynamics of WMRs with varying height.

  4. Experimental Slip Events as Possible Proxies for Fault Patch Slip During Earthquakes

    NASA Astrophysics Data System (ADS)

    Chang, J. C.; Lockner, D. A.; Reches, Z.

    2011-12-01

    The slip and strength histories of a fault patch during an earthquake are experimentally simulated with a high-speed rotary apparatus. The experimental fault comprises two solid cylindrical blocks with a raised-ring contact of 7 cm diameter and 1 cm width. Our conceptual model assumes that slip on a fault patch is initiated by the stress increase associated with the passage of an earthquake front, and that this slip is facilitated by dissipation of potential energy stored in the surrounding crust. To simulate this process in the laboratory, we first store kinetic energy by spinning up a 225 kg flywheel that is adjacent to, but not connected to, the locked fault. Then, the flywheel is engaged to the lower fault block via a fast-acting (<0.03 s) clutch, and the drive motor is turned off. This loading procedure produces slip behavior that has many similarities to the slip envisioned to occur along an earthquake patch. (1) In both cases, a finite energy is available to drive slip. (2) The initial dynamic stress rise leading to fault slip is rapid (<< 1 s). (3) Slip history is controlled by spontaneous interaction between fault strength and the stored energy. (4) Radiated seismic energy is probably a small fraction of the energy budget. We refer to our experiments as 'Earthquake-Like-Slip-Event' or ELSE. Direct measurements of slip-velocity, normal and shear stresses, fault-normal displacement, and temperature are recorded at 5 kHz sampling. We present synthesis of 43 ELSE runs with Sierra White granite, and 15 with Kasota dolomite. Samples were axially loaded up to 7 MPa, potential energy up to 25 MJ/m^2, and slip-velocity up to ~1.0 m/s; they produced slip-distances up to 5.55 m, and fault-normal displacement from -300 microns (closure) to 160 microns (dilation). The main ELSE observations and inferences are: (1) In most experiments, the strength drops significantly (~50-70%) during the early slip stage, and this weakening is associated with intense fault wear and gouge generation that lead to fault-lubrication; (2) Some experiments display no weakening, but strengthening, during the entire slip period; (3) In general, neither velocity nor strength reach a steady-state stage during sliding; (4) In terms of total energy dissipation, slip-distance, slip-velocity, and rise-time, ELSE experiments are comparable to earthquakes in the moment-magnitude range of Mw=3-8; and (5) the average-patch-strength appear to be the most useful proxy for ELSE magnitude. Application of these results to earthquakes is model-dependent and would require parameter scaling.

  5. Reflexive responses to slipping in bipedal running robots

    Microsoft Academic Search

    Gary N. Boone; Jessica K. Hodgins

    1995-01-01

    Many robot applications require traversing uneven or unmodeled terrain. This paper explores strategies for one class of difficult terrain: slippery surfaces. We evaluate several reflexive responses to a slip using a dynamically simulated, three-dimensional, bipedal robot. We explore two kinds of reaction strategies. One strategy continues the step, in which the slip occurred. The other lifts the slipping foot and

  6. Constraining fault constitutive behavior with slip and stress heterogeneity

    E-print Network

    Greer, Julia R.

    Constraining fault constitutive behavior with slip and stress heterogeneity B. T. Aagaard1 and T. H and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required on a vertical, planar strike-slip fault show that the conditions that lead to slip heterogeneity remain in place

  7. Seismic and geodetic constraints on Cascadia slow slip

    Microsoft Academic Search

    Aaron G. Wech; Kenneth C. Creager; Timothy I. Melbourne

    2009-01-01

    Automatically detected and located tremor epicenters from episodic tremor and slip (ETS) episodes in northern Cascadia provide a high-resolution map of Washington's slow slip region. Thousands of epicenters from the past four ETS events from 2004 to 2008 provide detailed map-view constraints that correlate with geodetic estimates of the simultaneous slow slip. Each of these ETS events exhibits remarkable similarity

  8. Measuring and incorporating slip in data-driven haptic rendering

    Microsoft Academic Search

    R. Hover; Matthias Harders

    2010-01-01

    In this paper we extended our data-driven haptic rendering approach towards slipping phenomena. In order to capture tool displacements on surfaces we designed a slip sensor based on an optical mouse sensor. Calibration experiments were performed to ensure accurate readings on rigid and deformable surfaces. For slow tool movements this calibration led to very accurate slip measurements. Moreover, we extended

  9. Study on Improved Maximum-Torque Slip Frequency Control

    Microsoft Academic Search

    Du Guiping; Zhang Weilin

    2010-01-01

    This paper introduces the main control methods of AC motor. Using traditional slip frequency control method, the PI parameters are hard to be determined, digitization of the current-slip curve is hard to be realized and the maximum torque cannot be obtained. A maximum-torque slip frequency control method is proposed to meet the requirements of mining locomotives. Simulation and experiment shows

  10. Quantifying effective slip length over micropatterned hydrophobic surfaces

    Microsoft Academic Search

    Peichun Tsai; Alisia M. Peters; Christophe Pirat; Matthias Wessling; Rob G. H. Lammertink; Detlef Lohse

    2009-01-01

    We employ microparticle image velocimetry to investigate laminar microflows in hydrophobic microstructured channels, in particular the slip length. These microchannels consist of longitudinal microgrooves, which can trap air and prompt a shear-free boundary condition and thus slippage enhancement. Our measurements reveal an increase in the slip length when the width of the microgrooves is enlarged. The result of the slip

  11. Influence of slip rheology on pressure casting of alumina

    Microsoft Academic Search

    R. Moreno; A. Salomoni; I. Stamenkovic

    1997-01-01

    Pressure slip casting has been developed more intensively since it can produce near net-shaped green bodies with shorter processing cycles. As with the other colloidal forming techniques, the preparation and control of stable, well-dispersed ceramic slips is considered a key parameter. In this study a series of alumina slips containing different kinds of dispersants including potential determining ions, counterions or

  12. Estimating Friction Using Incipient Slip Sensing During a Manipulation Task

    E-print Network

    Stanford University

    before significant object motion occurs. In an attempt to detect incipient slip signals that occur beforeEstimating Friction Using Incipient Slip Sensing During a Manipulation Task Marc R. Tremblay Mark R at the contact when these "incipient" slip signals occur, the controller obtains an accurate estimate

  13. Secondary Fracturing as a Tool for Unraveling Strike-Slip Fault Slip Behavior on Europa

    Microsoft Academic Search

    S. A. Kattenhorn; S. T. Marshall

    2003-01-01

    Secondary cracks are commonly produced at stress concentration points at the tips of faults. These so-called tailcracks form at an angle to the fault trace, with locations about the fault tips that indicate whether slip was left-lateral or right-lateral. Tailcracks are widespread on the surface of Jupiter's moon, Europa, and attest to the common occurrence of strike-slip faults. The crust

  14. Distributed Slip Model for Simulating Virtual Earthquakes

    NASA Astrophysics Data System (ADS)

    Shani-Kadmiel, S.; Tsesarsky, M.; Gvirtzman, Z.

    2014-12-01

    We develop a physics based, generic finite fault source, which we call the Distributed Slip Model (DSM) for simulating large virtual earthquakes. This task is a necessary step towards ground motion prediction in earthquake-prone areas with limited instrumental coverage. A reliable ground motion prediction based on virtual earthquakes must account for site, path, and source effects. Assessment of site effect mainly depends on near-surface material properties which are relatively well constrained, using geotechnical site data and borehole measurements. Assessment of path effect depends on the deeper geological structure, which is also typically known to an acceptable resolution. Contrarily to these two effects, which remain constant for a given area of interest, the earthquake rupture process and geometry varies from one earthquake to the other. In this study we focus on a finite fault source representation which is both generic and physics-based, for simulating large earthquakes where limited knowledge is available. Thirteen geometric and kinematic parameters are used to describe the smooth "pseudo-Gaussian" slip distribution, such that slip decays from a point of peak slip within an elliptical rupture patch to zero at the borders of the patch. Radiation pattern and spectral charectaristics of our DSM are compared to those of commonly used finite fault models, i.e., the classical Haskell's Model (HM) and the modified HM with Radial Rupture Propagation (HM-RRP) and the Point Source Model (PSM). Ground motion prediction based on our DSM benefits from the symmetry of the PSM and the directivity of the HM while overcoming inadequacy for modeling large earthquakes of the former and the non-physical uniform slip of the latter.

  15. The effect of subject awareness and prior slip experience on tribometer-based predictions of slip probability

    Microsoft Academic Search

    Gunter P. Siegmund; Tamika L. Heiden; David J. Sanderson; J. Timothy Inglis; John R. Brault

    2006-01-01

    Prior knowledge of potentially slippery conditions has been shown to alter normal human gait in slip and fall experiments. We sought to quantify how the empirical relationship between slip probability and available floor friction was affected by subject awareness and prior slip experience. Sixty-eight subjects (40 females, 28 males) walked over three different low-friction surfaces inserted periodically between non-slip control

  16. Floor slip resistance changes in food sector workshops: prevailing role played by “fouling”

    Microsoft Academic Search

    S Leclercq; H Saulnier

    2002-01-01

    Over 10% of occupational accidents are triggered by a slip. These accidents are more frequent in food sector workshops. Anti-slip floors are a means of preventing slips. Much has been done in terms of methodology to assess slip resistance and measurement of new floor slip resistance. To date, no study has dealt with time-related changes in slip resistance in the

  17. What are Slips, Trips, and Falls? Slip: An unexpected slide due to a loss of traction between

    E-print Network

    deYoung, Brad

    and manage stress and fatigue. What do you do if you see a slip, trip, or fall hazard on campus? You can/4 of all reported occupational injuries. #12;Who do slips, trips, and falls affect? Slips, trips, and falls report any potentially hazardous areas to Facilities Management (phone: 709-864-7600 or email: facman

  18. Downscaling of slip distribution for strong earthquakes

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Oya, S.; Kuzuha, Y.

    2013-12-01

    We intend to develop a downscaling model to enhance the earthquake slip distribution resolution. Slip distributions have been obtained by other researchers using various inversion methods. As a downscaling model, we are discussing fractal models that include mono-fractal models (fractional Brownian motion, fBm; fractional Lévy motion, fLm) and multi-fractal models as candidates. Log - log-linearity of k (wave number) versus E (k) (power spectrum) is the necessary condition for fractality: the slip distribution is expected to satisfy log - log-linearity described above if we can apply fractal model to a slip distribution as a downscaling model. Therefore, we conducted spectrum analyses using slip distributions of 11 earthquakes as explained below. 1) Spectrum analyses using one-dimensional slip distributions (strike direction) were conducted. 2) Averaging of some results of power spectrum (dip direction) was conducted. Results show that, from the viewpoint of log - log-linearity, applying a fractal model to slip distributions can be inferred as valid. We adopt the filtering method after Lavallée (2008) to generate fBm/ fLm. In that method, generated white noises (random numbers) are filtered using a power law type filter (log - log-linearity of the spectrum). Lavallée (2008) described that Lévy white noise that generates fLm is more appropriate than the Gaussian white noise which generates fBm. In addition, if the 'alpha' parameter of the Lévy law, which governs the degree of attenuation of tails of the probability distribution, is 2.0, then the Lévy distribution is equivalent to the Gauss distribution. We analyzed slip distributions of 11 earthquakes: the Tohoku earthquake (Wei et al., 2011), Haiti earthquake (Sladen, 2010), Simeulue earthquake (Sladen, 2008), eastern Sichuan earthquake (Sladen, 2008), Peru earthquake (Konca, 2007), Tocopilla earthquake (Sladen, 2007), Kuril earthquake (Sladen, 2007), Benkulu earthquake (Konca, 2007), and southern Java earthquake (Konca, 2006)). We obtained the following results. 1) Log - log-linearity (slope of the linear relationship is ' - ?') of k versus E(k) holds for all earthquakes. 2) For example, ? = 3.70 and ? = 1.96 for the Tohoku earthquake (2011) and ? = 4.16 and ? = 2.00 for the Haiti earthquake (2010). For these cases, the Gauss' law is appropriate because alpha is almost 2.00. 3) However, ? = 5.25 and ? = 1.25 for the Peru earthquake (2007) and ? = 2.24 and ? = 1.57 for the Simeulue earthquake (2008). For these earthquakes, the Lévy law is more appropriate because ? is far from 2.0. 4) Although Lavallée (2003, 2008) concluded that the Lévy law is more appropriate than the Gauss' law for white noise, which is later filtered, our results show that the Gauss law is appropriate for some earthquakes. Lavallée and Archuleta, 2003, Stochastic modeling of slip spatial complexities for the 1979 Imperial Valley, California, earthquake, GEOPHYSICAL RESEARCH LETTERS, 30(5). Lavallée, 2008, On the random nature of earthquake source and ground motion: A unified theory, ADVANCES IN GEOPHYSICS, 50, Chap 16.

  19. Effects of slip, slip rate, and shear heating on the friction of granite

    USGS Publications Warehouse

    Blanpied, M.L.; Tullis, T.E.; Weeks, J.D.

    1998-01-01

    The stability of fault slip is sensitive to the way in which frictional strength responds to changes in slip rate and in particular to the effective velocity dependence of steady state friction ????ss/?? ln V. This quantity can vary substantially with displacement, temperature and slip rate. To investigate the physical basis for this behavior and the possible influence of shear heating, we slid initially bare granite surfaces in unconfined rotary shear to displacements of hundreds of millimeters at normal stresses, ??n, of 10 and 25 MPa and at room temperature. We imposed step changes in slip rate within the range 10-2 to 103.5 ??m/s and also monitored frictional heating with thermistors embedded in the granite. The transient response of ?? to slip rate steps was fit to a rate- and state-dependent friction law using two state variables to estimate the values of several parameters in the constitutive law. The first 20 mm of slip shows rising friction and falling ????ss/?? ln V; further slip shows roughly constant friction, ????ss/?? ln V and parameter values, suggesting that a steady state condition is reached on the fault surface. At V ??? 10 ??m/s, ????ss/?? ln V = -0.004 ?? 0.001. At higher rates the response is sensitive to normal stress: At ??n = 25 MPa granite shows a transition to effective velocity strengthening (????ss/?? ln V = 0.008 ?? 0.004) at the highest slip rates tested. At 10 MPa granite shows a less dramatic change to ????ss/?? ln V ??? 0 at the highest rates. The maximum temperature measured in the granite is ???60??C at 25 MPa and 103.5 ??m/s. Temperatures are in general agreement with a numerical model of heat conduction which assumes spatially homogeneous frictional heating over the sliding surface. The simplest interpretation of our measurements of ????ss/?? ln V is that the granite is inherently veocity weakening (?????ss/??? In V 0 mimics velocity strengthening. These results have implications for the frictional behavior of faults during earthquakes. High slip rates may cause a switch to effective velocity strengthening which could limit peak coseismic slip rate and stress drop. For fluid-saturated faults, strengthening by this mechanism may be partly or fully offset by weakening due to thermal pressurization of a poorly drained pore fluid.

  20. Mw 8.6 Strike-Slip Earthquake off Sumatra and Slip Partitioning

    NASA Astrophysics Data System (ADS)

    Ishii, M.; Kiser, E.; Geist, E. L.

    2013-12-01

    The magnitude 8.6 earthquake that occurred on April 11, 2012 off the northwestern coast of Sumatra is an enigmatic event. It has a strike-slip mechanism, and is located at least 100 km from the closest plate boundary. This event is also followed about 2 hours later by an Mw 8.2 earthquake with similar mechanism. These earthquakes are well-recorded by seismic stations around the world, and we use the dense network of stations in Japan to constrain the locations and timings of the high-frequency energy radiation. The resulting back-projection images show a complicated rupture pattern involving multiple segments. Despite being strike-slip earthquakes, the Mw 8.6 and 8.2 events generated tsunamis that were observed by stations within and around the Indian Ocean. Of the 18 tide gauge/bottom-pressure sensors that recorded the Mw 8.6 earthquake, 8 stations also captured the arrival of the tsunami wave generated by the Mw 8.2 event. The differential travel times from the two events show strong azimuthal dependence, suggesting that the tsunami excitation from the Mw 8.6 earthquake is not confined to an area near the epicenter. The data show that there is at least one more source at the Ninety-East Ridge. The modeling results of the source extent of the Mw 8.6 earthquake using the seismic back-projection method and differential tsunami travel times are consistent with one another, and suggest that much of the slip occurs on faults with northwest-southeast strike, i.e., nearly parallel to the closest trench. Based upon these observations and the obliqueness of subduction at the trench, we suggest that the Mw 8.6 strike-slip event is a result of slip partitioning. The trench-parallel component of plate convergence is typically taken up by strike-slip faults on the over-riding plate, such as the Great Sumatran Fault, but it may also be accommodated by faults on the subducting plate. The Great Sumatran Fault is known to have slip deficit at its northernmost segment, and this deficit is compatible with the occurrence of the Mw 8.6 strike-slip earthquake. If the slip partitioning does occur on the subducting plate, the hazard potential for the strike-slip fault on the over-riding plate may be significantly reduced.

  1. Joint assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2010-01-01

    A joint assembly is provided which includes a drive assembly and a swivel mechanism. The drive assembly features a motor operatively associated with a plurality of drive shafts for driving auxiliary elements, and a plurality of swivel shafts for pivoting the drive assembly. The swivel mechanism engages the swivel shafts and has a fixable element that may be attached to a foundation. The swivel mechanism is adapted to cooperate with the swivel shafts to pivot the drive assembly with at least two degrees of freedom relative to the foundation. The joint assembly allows for all components to remain encased in a tight, compact, and sealed package, making it ideal for space, exploratory, and commercial applications.

  2. Uncovering the geodetic signature of silent slip through repeating earthquakes

    NASA Astrophysics Data System (ADS)

    Frank, William B.; Radiguet, Mathilde; Rousset, Baptiste; Shapiro, Nikolaï M.; Husker, Allen L.; Kostoglodov, Vladimir; Cotte, Nathalie; Campillo, Michel

    2015-04-01

    Slow transient slip that releases stress along the deep roots of plate interfaces is most often observed on regional GPS networks installed at the surface. The detection of slow slip is not trivial if the dislocation along the fault at depth does not generate a geodetic signal greater than the observational noise level. Instead of the typical workflow of comparing independently gathered seismic and geodetic observations to study slow slip, we use repeating low-frequency earthquakes to reveal a previously unobserved slow slip event. By aligning GPS time series with episodes of low-frequency earthquake activity and stacking, we identify a repeating transient slip event that generates a displacement at the surface that is hidden under noise prior to stacking. Our results suggest that the geodetic investigation of transient slip guided by seismological information is essential in exploring the spectrum of fault slip.

  3. FLOOR\\/SHOE SLIP RESISTANCE MEASUREMENT

    Microsoft Academic Search

    Don B. Chaffin; Jeffrey C. Woldstad; Anna Trujillo

    1992-01-01

    A variety of slip measurement devices exist that provide estimates of both static and dynamic coefficient-of-friction (COF) values between one's shoes and the floor. Unfortunately, different shoe sole\\/heel materials, floor conditions, and contaminants will affect the tests in ways that result in widely varying COF estimates. This paper reviews the basic physics of such tests and describes a set of

  4. Active and recent strike-slip tectonics

    Microsoft Academic Search

    Amos Nur; Mario Boccaletti

    1989-01-01

    An international workshop cosponsored by the Department of Geology, University of Florence, Italy and the Department of Geophysics, Stanford University, Stanford, Calif., was held in Florence, Italy, April 18-20, 1989,on the topic of active and recent strike-slip tectonics in the continental crust. Workshop participants from Turkey, Ethiopia, Israel, Greece, and various universities in Italy, Spain, West Germany, France, the United

  5. Crystal plasticity finite element analysis of deformation behaviour in SAC305 solder joint

    NASA Astrophysics Data System (ADS)

    Darbandi, Payam

    Due to the awareness of the potential health hazards associated with the toxicity of lead (Pb), actions have been taken to eliminate or reduce the use of Pb in consumer products. Among those, tin (Sn) solders have been used for the assembly of electronic systems. Anisotropy is of significant importance in all structural metals, but this characteristic is unusually strong in Sn, making Sn based solder joints one of the best examples of the influence of anisotropy. The effect of anisotropy arising from the crystal structure of tin and large grain microstructure on the microstructure and the evolution of constitutive responses of microscale SAC305 solder joints is investigated. Insights into the effects of key microstructural features and dominant plastic deformation mechanisms influencing the measured relative activity of slip systems in SAC305 are obtained from a combination of optical microscopy, orientation imaging microscopy (OIM), slip plane trace analysis and crystal plasticity finite element (CPFE) modeling. Package level SAC305 specimens were subjected to shear deformation in sequential steps and characterized using optical microscopy and OIM to identify the activity of slip systems. X-ray micro Laue diffraction and high energy monochromatic X-ray beam were employed to characterize the joint scale tensile samples to provide necessary information to be able to compare and validate the CPFE model. A CPFE model was developed that can account for relative ease of activating slip systems in SAC305 solder based upon the statistical estimation based on correlation between the critical resolved shear stress and the probability of activating various slip systems. The results from simulations show that the CPFE model developed using the statistical analysis of activity of slip system not only can satisfy the requirements associated with kinematic of plastic deformation in crystal coordinate systems (activity of slip systems) and global coordinate system (shape changes) but also this model is able to predict the evolution of stress in joint level SAC305 sample.

  6. Torque converter slipping clutch and control

    SciTech Connect

    Wonn, Q.E.

    1987-02-17

    This patent describes a controlled slip torque converter and clutch comprising; an input shell; a torque converter means having an impeller drivingly connected with the input shell, a turbine and a stator disposed for toroidal flow, the torque converter means transmitting drive torque from the impeller to the turbine in a slipping relation; clutch means engageable in response to fluid pressure to limit the slip relation between the impeller and turbine and being disposed in drive relation between the input shell and the turbine and cooperating therewith to form clutch apply chamber means and clutch release chamber means; variable flow restriction means including spring means disposed between the clutch apply chamber means and the release chamber means for providing a controlled flow from the apply chamber means to the release chamber means; and viscous damper means disposed in parallel relation with the spring means on the variable flow restriction means and being responsive to torque disturbances at the clutch means and the turbine to restrict the rate at which the flow restriction means varies.

  7. Slip length crossover on a graphene surface

    NASA Astrophysics Data System (ADS)

    Liang, Zhi; Keblinski, Pawel

    2015-04-01

    Using equilibrium and non-equilibrium molecular dynamics simulations, we study the flow of argon fluid above the critical temperature in a planar nanochannel delimited by graphene walls. We observe that, as a function of pressure, the slip length first decreases due to the decreasing mean free path of gas molecules, reaches the minimum value when the pressure is close to the critical pressure, and then increases with further increase in pressure. We demonstrate that the slip length increase at high pressures is due to the fact that the viscosity of fluid increases much faster with pressure than the friction coefficient between the fluid and the graphene. This behavior is clearly exhibited in the case of graphene due to a very smooth potential landscape originating from a very high atomic density of graphene planes. By contrast, on surfaces with lower atomic density, such as an (100) Au surface, the slip length for high fluid pressures is essentially zero, regardless of the nature of interaction between fluid and the solid wall.

  8. The 2012 Brawley swarm triggered by injection-induced aseismic slip

    NASA Astrophysics Data System (ADS)

    Wei, Shengji; Avouac, Jean-Philippe; Hudnut, Kenneth W.; Donnellan, Andrea; Parker, Jay W.; Graves, Robert W.; Helmberger, Don; Fielding, Eric; Liu, Zhen; Cappa, Frederic; Eneva, Mariana

    2015-07-01

    It has long been known that fluid injection or withdrawal can induce earthquakes, but the underlying mechanisms remain elusive. For example, the 2012 Brawley swarm, which produced two strike-slip shocks with magnitudes larger than 5.3 and surface ruptures in the close vicinity of a geothermal field, started with earthquakes about 5 km deeper than the injection depth (?1.5 km). This makes the causality between the injection and seismicity unclear. Here, we jointly analyze broadband and strong motion waveforms, UAVSAR, leveling measurements and field observations to reveal the detailed seismic and aseismic faulting behaviors associated with the 2012 Brawley swarm. In particular, path calibration established from smaller events in the swarm allows waveform inversion to be conducted up to 3 Hz to resolve finite rupture process of the Mw 4.7 normal event. Our results show that the 2012 earthquake sequence was preceded by aseismic slip on a shallow normal fault beneath the geothermal field. Aseismic slip initiated in 2010 when injection rate rapidly increased and triggered the following earthquakes subsequently, including unusually shallow and relatively high frequency seismic excitations on the normal fault. In this example, seismicity is induced indirectly by fluid injection, a result of mediation by aseismic creep, rather than directly by a pore pressure increase at the location of the earthquakes.

  9. Great Earthquakes With and Without Large Slip to the Trench

    NASA Astrophysics Data System (ADS)

    Mori, J. J.

    2013-12-01

    The 2011 Tohoku-oki earthquake produced a huge amount of slip (40 to 60 meters) on the shallow portion of the subduction zone close to the trench. This large displacement was largely unexpected for this region and caused the very large and damaging tsunami along the northeast coast of Honshu. For other subduction zones around the world, we examine the possibility of large slip to the trench in past large and great earthquakes. Since the trench region is generally far offshore, it is often difficult to resolve the amount of slip from onland geodetic and strong-motion data. We use a variety of observations, including slip distribution models, aftershock locations, local coastal deformation, and tsunami heights to determine which events likely had large amounts of slip close to the trench. Tsunami earthquakes, such as 1992 Nicaragua and 2006 Java likely had large shallow slip. Some typical subduction earthquakes, such as 1968 Tokachi-oki and 2003 Tokachi-oki (located in regions north of the source area of the 2011 Tohoku-oki earthquake) likely did not. We will discuss possible factors that influence the slip distribution on the shallow area of subduction megathrusts. Using results from the Japan Trench Fast Drilling Project (JFAST) which sampled the fault in the region of large slip, we can begin to understand the conditions of very large fault slip. Are there characteristic features in the material properties for faults that have large slip ? Can we determine if these regions have high plate coupling and accumulate stress ?

  10. Coseismic slip distribution of the 1923 Kanto earthquake, Japan

    USGS Publications Warehouse

    Pollitz, F.F.; Nyst, M.; Nishimura, T.; Thatcher, W.

    2005-01-01

    The slip distribution associated with the 1923 M = 7.9 Kanto, Japan, earthquake is reexamined in light of new data and modeling. We utilize a combination of first-order triangulation, second-order triangulation, and leveling data in order to constrain the coseismic deformation. The second-order triangulation data, which have not been utilized in previous studies of 1923 coseismic deformation, are associated with only slightly smaller errors than the first-order triangulation data and expand the available triangulation data set by about a factor of 10. Interpretation of these data in terms of uniform-slip models in a companion study by Nyst et al. shows that a model involving uniform coseismic slip on two distinct rupture planes explains the data very well and matches or exceeds the fit obtained by previous studies, even one which involved distributed slip. Using the geometry of the Nyst et al. two-plane slip model, we perform inversions of the same geodetic data set for distributed slip. Our preferred model of distributed slip on the Philippine Sea plate interface has a moment magnitude of 7.86. We find slip maxima of ???8-9 m beneath Odawara and ???7-8 m beneath the Miura peninsula, with a roughly 2:1 ratio of strike-slip to dip-slip motion, in agreement with a previous study. However, the Miura slip maximum is imaged as a more broadly extended feature in our study, with the high-slip region continuing from the Miura peninsula to the southern Boso peninsula region. The second-order triangulation data provide good evidence for ???3 m right-lateral strike slip on a 35-km-long splay structure occupying the volume between the upper surface of the descending Philippine Sea plate and the southern Boso peninsula. Copyright 2005 by the American Geophysical Union.

  11. Long-term slip deficit and the forecasting of slip in future earthquakes

    NASA Astrophysics Data System (ADS)

    McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

    2014-05-01

    In the last decade a series of devastating earthquakes have between them killed more than three-quarters of a million people. None of the events were formally forecast and have been repeatedly referred to a seismological 'surprises'. Here we argue that while earthquakes within the wide swath of diffuse deformation comprising the Alpine-Himalayan belt pose a set of particularly difficult set of challenges, earthquakes which are driven by high strain-rates at plate boundaries and which have relatively short nominal recurrence times might be forecast if the data exists to perform long-term slip deficit modelling and stress reconstruction. We show that two instrumentally recorded event on the Sumatran margin in 2007 and 2010 occurred in regions of high slip deficit identified by reconstruction of slip in historical earthquakes in 1797 and 1833 under the Mentawai Islands using more than 200 years of geodetic data recorded in the stratigraphy of coral micro-atolls growing there. In the presentation we will describe the data and a new Bayesian-Monte Carlo slip reconstruction technique. The technique is based on the stochastic forward modelling of many slip distributions each using the same set of elastic Green's functions to estimate, by superposition of contributions from each fault cell, the vertical displacement at the coral locations resulting from each simulated event. Every solution, weighted by its goodness of fit to the data, is added to a stack whose final values contain an estimate of the most likely distribution of slip in the historical earthquakes. Further, we estimate the Kullback-Liebler divergence over the fault area providing a non-arbitrary assessment of the spatial distribution of information gain, identifying regions of low- and high- model confidence. We then model the long-term slip deficit on the megathrust assuming a zero of stress immediately after the 1652 Mentawai Islands earthquake. We use the resulting slip deficit field to compute the entire stress field including both secular loading and earthquake interaction stresses. We show that the spatial distribution of energy release in the 2007 and 2010 earthquakes correlates strongly with regions of high slip deficit accumulated over the previous 350 years and that in principle both could have been identified as areas of particularly high seismic hazard. The following more general seismological lessons emerge from our work: 1 At least for this region of this margin, the characteristic earthquake concept entirely fails to explain the data 2 Earthquake slip tessellates the fault plane under the Mentawai Islands rather than repeatedly breaking the same patch. 3 The tessellation by high slip is largely constrained by the interface coupling distribution (which, of course, played no part in the slip reconstruction). 4 Homogeneous loading of a heterogeneous fault in a linear-elastic medium explains all the observations, no rheological time dependence is necessary. 5 Even small amounts of nonlinearity in the rupture process would ensure that this sequence will not be repeated, calling into question many long-standing, fundamental concepts in earthquake science.

  12. Combined UAVSAR and GPS Estimates of Fault Slip for the M 6.0 South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Donnellan, A.; Parker, J. W.; Hawkins, B.; Hensley, S.; Jones, C. E.; Owen, S. E.; Moore, A. W.; Wang, J.; Pierce, M. E.; Rundle, J. B.

    2014-12-01

    Combined UAVSAR and GPS Estimates of Fault Slip for the M 6.0 South Napa Earthquake Andrea Donnellan, Jay Parker, Brian Hawkins, Scott Hensley, Cathleen Jones, Susan Owen, Angelyn Moore Jet Propulsion Laboratory, California Institute of Technology Marlon Pierce, Jun Wang Indiana University John Rundle University of California, Davis The South Napa to Santa Rosa area has been observed with NASA's UAVSAR since late 2009 as part of an experiment to monitor areas identified as having a high probability of an earthquake. The M 6.0 South Napa earthquake occurred on 24 August 2014. The area was flown 29 May 2014 preceeding the earthquake, and again on 29 August 2014, five days after the earthquake. The UAVSAR results show slip on a single fault at the south end of the rupture near the epicenter of the event. The rupture branches out into multiple faults further north near the Napa area. A combined inversion of rapid GPS results and the unwrapped UAVSAR interferogram indicate nearly pure strike slip motion. Using this assumption, the UAVSAR data show horizontal right-lateral slip across the fault of 19 cm at the south end of the rupture and increasing to 70 cm northward over a distance of 6.5 km. The joint inversion indicates slip of ~30 cm on a network of sub-parallel faults is concentrated in a zone about 17 km long. The lower depths of the faults are 5-8.5 km. The eastern two sub-parallel faults break the surface, while three faults to the west are buried at depths ranging from 2-6 km with deeper depths to the north and west. The geodetic moment release is equivalent to a M 6.1 event. Additional ruptures are observed in the interferogram, but the inversions suggest that they represent superficial slip that does not contribute to the overall moment release.

  13. Identification of maximum road friction coefficient and optimal slip ratio based on road type recognition

    NASA Astrophysics Data System (ADS)

    Guan, Hsin; Wang, Bo; Lu, Pingping; Xu, Liang

    2014-09-01

    The identification of maximum road friction coefficient and optimal slip ratio is crucial to vehicle dynamics and control. However, it is always not easy to identify the maximum road friction coefficient with high robustness and good adaptability to various vehicle operating conditions. The existing investigations on robust identification of maximum road friction coefficient are unsatisfactory. In this paper, an identification approach based on road type recognition is proposed for the robust identification of maximum road friction coefficient and optimal slip ratio. The instantaneous road friction coefficient is estimated through the recursive least square with a forgetting factor method based on the single wheel model, and the estimated road friction coefficient and slip ratio are grouped in a set of samples in a small time interval before the current time, which are updated with time progressing. The current road type is recognized by comparing the samples of the estimated road friction coefficient with the standard road friction coefficient of each typical road, and the minimum statistical error is used as the recognition principle to improve identification robustness. Once the road type is recognized, the maximum road friction coefficient and optimal slip ratio are determined. The numerical simulation tests are conducted on two typical road friction conditions(single-friction and joint-friction) by using CarSim software. The test results show that there is little identification error between the identified maximum road friction coefficient and the pre-set value in CarSim. The proposed identification method has good robustness performance to external disturbances and good adaptability to various vehicle operating conditions and road variations, and the identification results can be used for the adjustment of vehicle active safety control strategies.

  14. Slip statistics of dislocation avalanches under different loading modes.

    PubMed

    Maaß, R; Wraith, M; Uhl, J T; Greer, J R; Dahmen, K A

    2015-04-01

    Slowly compressed microcrystals deform via intermittent slip events, observed as displacement jumps or stress drops. Experiments often use one of two loading modes: an increasing applied stress (stress driven, soft), or a constant strain rate (strain driven, hard). In this work we experimentally test the influence of the deformation loading conditions on the scaling behavior of slip events. It is found that these common deformation modes strongly affect time series properties, but not the scaling behavior of the slip statistics when analyzed with a mean-field model. With increasing plastic strain, the slip events are found to be smaller and more frequent when strain driven, and the slip-size distributions obtained for both drives collapse onto the same scaling function with the same exponents. The experimental results agree with the predictions of the used mean-field model, linking the slip behavior under different loading modes. PMID:25974504

  15. Slip-and-fall hazards in the marine environment.

    PubMed

    Pazos, Hector V

    2003-03-01

    The marine environment introduces several additional factors in the analysis of slip-and-fall accidents that are normally not considered in studies of slip-and-fall situations in other industries. The generally accepted industry standard that a value of 0.5 and above for the static anti-slip coefficient of friction may be safe on a dry walkway surface, in a non-marine environment, but it may not be sufficiently safe in most marine environments. PMID:12674992

  16. Dynamic model with slip for wheeled omnidirectional robots

    Microsoft Academic Search

    Robert L. Williams II; Brian E. Carter; Paolo Gallina; Giulio Rosati

    2002-01-01

    A dynamic model is presented for omni-directional wheeled mobile robots, including wheel\\/motion surface slip. We derive the dynamics model, experimentally measure friction coefficients, and measure the force to cause slip (to validate our friction model). Dynamic simulation examples are presented to demonstrate omni-directional motion with slip. After developing an improved friction model, compared to our initial model, the simulation results

  17. DEM simulation of growth normal fault slip

    NASA Astrophysics Data System (ADS)

    Chu, Sheng-Shin; Lin, Ming-Lang; Nien, Wie-Tung; Chan, Pei-Chen

    2014-05-01

    Slip of the fault can cause deformation of shallower soil layers and lead to the destruction of infrastructures. Shanchiao fault on the west side of the Taipei basin is categorized. The activities of Shanchiao fault will cause the quaternary sediments underneath the Taipei basin to become deformed. This will cause damage to structures, traffic construction, and utility lines within the area. It is determined from data of geological drilling and dating, Shanchiao fault has growth fault. In experiment, a sand box model was built with non-cohesive sand soil to simulate the existence of growth fault in Shanchiao Fault and forecast the effect on scope of shear band development and ground differential deformation. The results of the experiment showed that when a normal fault containing growth fault, at the offset of base rock the shear band will develop upward along with the weak side of shear band of the original topped soil layer, and this shear band will develop to surface much faster than that of single top layer. The offset ratio (basement slip / lower top soil thickness) required is only about 1/3 of that of single cover soil layer. In this research, it is tried to conduct numerical simulation of sand box experiment with a Discrete Element Method program, PFC2D, to simulate the upper covering sand layer shear band development pace and scope of normal growth fault slip. Results of simulation indicated, it is very close to the outcome of sand box experiment. It can be extended to application in water pipeline project design around fault zone in the future. Keywords: Taipei Basin, Shanchiao fault, growth fault, PFC2D

  18. Strong dynamical effects during stick-slip adhesive peeling

    NASA Astrophysics Data System (ADS)

    Dalbe, Marie-Julie; Santucci, Stephane; Vanel, Loic; Cortet, Pierre-Philippe

    2014-03-01

    We consider the classical problem of the stick-slip dynamics observed when peeling an adhesive tape at a constant velocity. From fast imaging recordings, we extract the dependencies of the stick and slip phases durations with the imposed peeling velocity and peeled ribbon length. Predictions of Maugis and Barquins [in Adhesion 12, edited by K.W. Allen, Elsevier ASP, London, 1988, pp. 205-222] based on a quasistatic assumption succeed to describe quantitatively our measurements of the stick phase duration. Such model however fails to predict the full stick-slip cycle duration, revealing strong dynamical effects during the slip phase.

  19. Inverting measurements of surface slip on the Superstition Hills fault

    USGS Publications Warehouse

    Boatwright, J.; Budding, K.E.; Sharp, R.V.

    1989-01-01

    We derive and test a set of inversions of surface-slip measurements based on the empirical relation u(t)=uf/(1 + T/t)c proposed by Sharp and Saxton (1989) to estimate the final slip uf, the power-law exponent c, and the power-law duration T. At short times, Sharp's relation behaves like the simple power law, u(t)~u1tc, where u1 is the initial slip, that is, the slip at 1 day after the earthquake. At long times, the slip approaches the final slip asymptotically. The inversions are designed in part to exploit the accuracy of measurements of differential slip; that is, measurements of surface slip which are made relative to a set of nails or stakes emplaced after the earthquake. We apply the inversions to slip measurements made at 53 sites along the Superstition Hills fault for the 11 months following the M=6.2 and 6.6 earthqakes of 24 November 1987. -from Authors

  20. Slip flow of diverse liquids on robust superomniphobic surfaces.

    PubMed

    Wu, Yang; Cai, Meirong; Li, Zhenquan; Song, Xinwang; Wang, Hongyan; Pei, Xiaowei; Zhou, Feng

    2014-01-15

    Water slips exist over superhydrophobic solid surfaces, but the slip flow of diverse liquids on a single surface has not been deliberately studied to date. Here, we report the slip flow behavior of a variety of liquids with different surface tensions and viscosities on a robust omniphobic surface. This surface displayed a dramatic slippage effect and thus a high drag reduction efficiency of approximately 10-20% for all liquids, depending on both liquid viscosity and surface energy. The observed liquid slip was attributed to the surface dual micro/nanostructure and the low-surface-energy coating. PMID:24231078

  1. Joint x-ray

    MedlinePLUS

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  2. Joint Aspiration (Arthrocentesis)

    MedlinePLUS

    ... the joint. It is usually due to a bacterial infection in the joint. Joint aspiration helps to diagnose ... at the time of the test. If a bacterial infection such as septic arthritis is suspected, a culture ...

  3. Joint Instability and Osteoarthritis

    PubMed Central

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  4. Microfluidics: The no-slip boundary condition

    E-print Network

    Eric Lauga; Michael P. Brenner; Howard A. Stone

    2005-09-28

    The no-slip boundary condition at a solid-liquid interface is at the center of our understanding of fluid mechanics. However, this condition is an assumption that cannot be derived from first principles and could, in theory, be violated. We present a review of recent experimental, numerical and theoretical investigations on the subject. The physical picture that emerges is that of a complex behavior at a liquid/solid interface, involving an interplay of many physico-chemical parameters, including wetting, shear rate, pressure, surface charge, surface roughness, impurities and dissolved gas.

  5. Stick-slip statistics in atomic friction

    NASA Astrophysics Data System (ADS)

    Evstigneev, Mykhaylo; Reimann, Peter

    2013-05-01

    We theoretically study atomic friction experiments in the stick-slip regime within the framework of the Prandtl-Tomlinson model. We derive a differential equation describing the force probability distribution. Approximate analytical solutions of this equation are found for the asymptotic cases of high and low effective spring constant, but for arbitrary pulling velocities. Excellent accuracy of these approximate expressions is demonstrated numerically. In particular, the result for the mean force, although obtained for small spring constants, is shown to be accurate also somewhat outside of its expected validity range.

  6. Slip Resistance of Casual Footwear: Implications for Falls in Older Adults

    Microsoft Academic Search

    Hylton B. Menz; Stephen R. Lord; Andrew S. McIntosh

    2001-01-01

    Background: A large proportion of falls in older people are caused by slipping. Previous occupational safety research suggests that inadequate footwear may contribute to slipping accidents; however, no studies have assessed the slip resistance of casual footwear. Objective: To evaluate the slip resistance of different types of casual footwear over a range of common household surfaces. Methods: The slip resistance

  7. Assessment of anti-slip devices from healthy individuals in different ages walking on slippery surfaces

    Microsoft Academic Search

    Gunvor Gard; Glenn Berggård

    2006-01-01

    The interest for effective preventive strategies for slips and falls is growing. Much remains to be done, however, to prevent slips and falls in the traffic environment. Using an appropriate anti-slip device may reduce the risk of slips and falls on different surfaces outdoors during winter. The aim of this study was to evaluate the best anti-slip devices of different

  8. EMG and kinematic responses to unexpected slips after slip training in virtual reality.

    PubMed

    Parijat, Prakriti; Lockhart, Thurmon E; Liu, Jian

    2015-02-01

    The objective of the study was to design a virtual reality (VR) training to induce perturbation in older adults similar to a slip and examine the effect of the training on kinematic and muscular responses in older adults. Twenty-four older adults were involved in a laboratory study and randomly assigned to two groups (VR training and control). Both groups went through three sessions including baseline slip, training, and transfer of training on slippery surface. The training group experienced 12 simulated slips using a visual perturbation induced by tilting a VR scene while walking on the treadmill and the control group completed normal walking during the training session. Kinematic, kinetic, and electromyography data were collected during all the sessions. Results demonstrated the proactive adjustments such as increased trunk flexion at heel contact after training. Reactive adjustments included reduced time to peak activations of knee flexors, reduced knee coactivation, reduced time to trunk flexion, and reduced trunk angular velocity after training. In conclusion, the study findings indicate that the VR training was able to generate a perturbation in older adults that evoked recovery reactions and such motor skill can be transferred to the actual slip trials. PMID:25296401

  9. EMG and Kinematic Responses to Unexpected Slips After Slip Training in Virtual Reality

    PubMed Central

    Parijat, Prakriti; Lockhart, Thurmon E.

    2015-01-01

    The objective of the study was to design a virtual reality (VR) training to induce perturbation in older adults similar to a slip and examine the effect of the training on kinematic and muscular responses in older adults. Twenty-four older adults were involved in a laboratory study and randomly assigned to two groups (virtual reality training and control). Both groups went through three sessions including baseline slip, training, and transfer of training on slippery surface. The training group experienced twelve simulated slips using a visual perturbation induced by tilting a virtual reality scene while walking on the treadmill and the control group completed normal walking during the training session. Kinematic, kinetic, and EMG data were collected during all the sessions. Results demonstrated the proactive adjustments such as increased trunk flexion at heel contact after training. Reactive adjustments included reduced time to peak activations of knee flexors, reduced knee coactivation, reduced time to trunk flexion, and reduced trunk angular velocity after training. In conclusion, the study findings indicate that the VR training was able to generate a perturbation in older adults that evoked recovery reactions and such motor skill can be transferred to the actual slip trials. PMID:25296401

  10. Slip-localization within confined gouge powder sheared at moderate to high slip-velocity

    NASA Astrophysics Data System (ADS)

    Reches, Zeev; Chen, Xiaofeng; Morgan, Chance; Madden, Andrew

    2015-04-01

    Slip along faults in the upper crust is always associated with comminution and formation of non-cohesive gouge powder that can be lithified to cataclasite. Typically, the fine-grained powders (grain-size < 1 micron) build a 1-10 cm thick inner-core of a fault-zone. The ubiquitous occurrence of gouge powder implies that gouge properties may control the dynamic weakening of faults. Testing these properties is the present objective. We built a Confined ROtary Cell, CROC, with a ring-shape, ~3 mm thick gouge chamber, with 62.5 and 81.2 mm of inner and outer diameters. The sheared powder is sealed by two sets of seals pressurized by nitrogen. In CROC, we can control the pore-pressure and to inject fluids, and to monitor CO2 and H2O concentration; in addition, we monitor the standard mechanical parameters (slip velocity, stresses, dilation, and temperature). We tested six types of granular materials (starting grain-size in microns): Talc (<250), Kasota dolomite (125-250), ooides grains (125-250), San Andreas fault zone powder (< 840), montmorillonite powder (1-2), kaolinite powder and gypsum. The experimental slip-velocity ranged 0.001-1 m/s, slip distances from a few tens of cm to tens of m, effective normal stress up to 6.1 MPa. The central ultra-microscopic (SEM) observation is that almost invariably the slip was localized along principal-slip-zone (PSZ) within the granular layer. Even though the starting material was loose, coarse granular material, the developed PSZ was cohesive, hard, smooth and shining. The PSZ is about 1 micron thick, and built of agglomerated, ultra-fine grains (20-50 nm) that were pulverized from the original granular material. We noted that PSZs of the different tested compositions display similar characteristics in terms of structure, grain size, and roughness. Further, we found striking similarities between PSZ in the granular samples and the PZS that developed along experimental faults made of solid rock that were sheared at similar conditions. The ultra-fine grains and extreme slip localization in these experiments are generally similar to ultra-cataclasites found in exhumed faults-zones, and the intensely pulverized gouge found in drilling across active faults.

  11. Fluid pressures at the shoe-floor-contaminant interface during slips: effects of tread and implications on slip severity.

    PubMed

    Beschorner, Kurt E; Albert, Devon L; Chambers, April J; Redfern, Mark S

    2014-01-22

    Previous research on slip and fall accidents has suggested that pressurized fluid between the shoe and floor is responsible for initiating slips yet this effect has not been verified experimentally. This study aimed to (1) measure hydrodynamic pressures during slipping for treaded and untreaded conditions; (2) determine the effects of fluid pressure on slip severity; and (3) quantify how fluid pressures vary with instantaneous resultant slipping speed, position on the shoe surface, and throughout the progression of the slip. Eighteen subjects walked on known dry and unexpected slippery floors, while wearing treaded and untreaded shoes. Fluid pressure sensors, embedded in the floor, recorded hydrodynamic pressures during slipping. The maximum fluid pressures (mean+/-standard deviation) were significantly higher for the untreaded conditions (124+/-75 kPa) than the treaded conditions (1.1+/-0.29 kPa). Maximum fluid pressures were positively correlated with peak slipping speed (r=0.87), suggesting that higher fluid pressures, which are associated with untreaded conditions, resulted in more severe slips. Instantaneous resultant slipping speed and position of sensor relative to the shoe sole and walking direction explained 41% of the fluid pressure variability. Fluid pressures were primarily observed for untreaded conditions. This study confirms that fluid pressures are relevant to slipping events, consistent with fluid dynamics theory (i.e. the Reynolds equation), and can be modified with shoe tread design. The results suggest that the occurrence and severity of unexpected slips can be reduced by designing shoes/floors that reduce underfoot fluid pressures. PMID:24267270

  12. Stress-Breakdown Time and Slip-Weakening Distance Inferred from Slip-Velocity Functions on Earthquake Faults

    Microsoft Academic Search

    Takeshi Mikumo; Kim B. Olsen; Eiichi Fukuyama; Yuji Yagi

    2003-01-01

    We estimate the critical slip-weakening distance on earthquake faults by using a new approach, which is independent of the estimate of fracture energy or radiated seismic energy. The approach is to find a physically based relation between the breakdown time of shear stress Tb, the time of peak slip-velocity Tpv, and the slip-weakening distance Dc, from the time histories of

  13. Experimental Characterization of Hysteresis in a Revolute Joint for Precision Deployable Structures

    NASA Technical Reports Server (NTRS)

    Lake, Mark S.; Fung, Jimmy; Gloss, Kevin; Liechty, Derek S.

    1997-01-01

    Recent studies of the micro-dynamic behavior of a deployable telescope metering truss have identified instabilities in the equilibrium shape of the truss in response to low-energy dynamic loading. Analyses indicate that these micro-dynamic instabilities arise from stick-slip friction within the truss joints (e.g., hinges and latches). The present study characterizes the low-magnitude quasi-static load cycle response of the precision revolute joints incorporated in the deployable telescope metering truss, and specifically, the hysteretic response of these joints caused by stick-slip friction within the joint. Detailed descriptions are presented of the test setup and data reduction algorithms, including discussions of data-error sources and data-filtering techniques. Test results are presented from thirteen specimens, and the effects of joint preload and manufacturing tolerances are investigated. Using a simplified model of stick-slip friction, a relationship is made between joint load-cycle behavior and micro-dynamic dimensional instabilities in the deployable telescope metering truss.

  14. Western Joint Occupational Health and Safety Committee Workplace Safety Inspection Guide/Checklist

    E-print Network

    Sinnamon, Gordon J.

    Western Joint Occupational Health and Safety Committee Workplace Safety Inspection Guide) by the supervisor? Basic Safety Y N N/A Are aisles, walkways and exits clear and all walking surfaces slip free? Y N N/A Is there a current inventory all hazardous substances in the lab? Y N N/A Do the workers know

  15. 46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...104.5.1(a)). (a) Flanged or butt-welded joints are required for Classes...slip-on flanges are not permitted and butt-welding flanges are required. The...welding flanges is not permitted and a butt weld type connection must be...

  16. 46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...104.5.1(a)). (a) Flanged or butt-welded joints are required for Classes...slip-on flanges are not permitted and butt-welding flanges are required. The...welding flanges is not permitted and a butt weld type connection must be...

  17. 46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...104.5.1(a)). (a) Flanged or butt-welded joints are required for Classes...slip-on flanges are not permitted and butt-welding flanges are required. The...welding flanges is not permitted and a butt weld type connection must be...

  18. 46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...104.5.1(a)). (a) Flanged or butt-welded joints are required for Classes...slip-on flanges are not permitted and butt-welding flanges are required. The...welding flanges is not permitted and a butt weld type connection must be...

  19. The mechanics and tribology of fretting fatigue with application to riveted lap joints

    Microsoft Academic Search

    Matthew Paul Szolwinski

    1998-01-01

    Fretting is the synergistic combination of wear, corrosion, and fatigue damage mechanisms driven by the partial slip of contacting surfaces. The surface microslip and near-surface contact stresses associated with fretting can lead to severe reduction in service lifetimes of contacting components as diversified as bearings, turbine blades and mechanically-fastened joints, both structural and biological. This tribologically induced degradation has come

  20. Statistics from granular stick-slip experiment

    NASA Astrophysics Data System (ADS)

    Abed Zadeh, Aghil; Bares, Jonathan; Behringer, Robert

    2015-03-01

    We carry out experiments to characterize stick-slip for granular materials. In our experiment, a constant speed stage pulls a slider which rests on a vertical bed of circular photoelastic particles in a 2D system. The stage is connected to the slider by a spring. We measure the force on the spring as well as the slider's acceleration by a force sensor attached to the spring and accelerometers on the slider. The distributions of energy release and time duration of avalanches during slip obey power laws. We apply a novel event recognition approach using wavelets to extract the avalanche properties. We compare statistics from the wavelet approach with those obtained by typical methods, to show how noise can change the distribution of events. We analyze the power spectrum of various quantities to understand the effect of the loading speed and of the spring stiffness on the statistical behavior of the system. Finally, from a more local point of view and by using a high speed camera and the photoelastic properties of our particles, we characterize the internal granular structure during avalanches. This work is supported by NSF Grant DMR1206351 and NASA Grant NNX10AU01G.

  1. Use of free serratus anterior muscle slips for the reconstruction of dorsal-side defects of the hand resulting from hot press injury.

    PubMed

    Topalan, Murat; Ozden, Burcu Celet; Aydin, Atakan; Erer, Metin

    2004-01-01

    Mutilation of the hand as a result of hot press injury, the common characteristics of which are extensive soft tissue and extensor tendon loss, metacarpal and phalangeal necrosis, exposition of multiple joints, and infection, presents a serious challenge to the hand surgeon. Free transfer of the inferior three slips of the serratus anterior muscle is a useful surgical option for the reconstruction of dorsal-side defects in the hand. The versatility of the three separate slips, which are easily divisible for contouring, enables individual reconstruction of the different digits. Long vascular pedicle, low donor-site morbidity, and durability are other advantages. Four male patients with hot press injury of the dorsal side of the hand were treated with free transfer of serratus anterior muscle slips and split-thickness skin grafts. Follow-up period ranged between 5 and 12 years. Late functional and cosmetic results are presented. PMID:15247833

  2. How is a stick slip rupture initiated?

    NASA Astrophysics Data System (ADS)

    Fukuyama, E.; Mizoguchi, K.; Yamashita, F.; Kawakata, H.; Takizawa, S.

    2013-12-01

    We investigated the initiation process of stick slip events that occurred during large scale rock friction experiments conducted on the large scale shaking table at NIED (Fukuyama et al., 2012, AGU Fall meeting). We used a pair of Indian gabbro rock samples stacked vertically and applied normal and shear forces. The sliding area between the samples is 1.5m in length and 0.1m in width. We conducted a sequence of experiments using the same rock sample, and before each experiment we removed gouge particles created during the previous experiment by a brush and a cleaner. Here, we show the experiments under constant slip velocity of 0.1mm/s with constant normal stress of 2.7MPa (LB04-003) or 6.7MPa (LB04-005); the final displacement reached 0.04m. We used 44 acoustic sensors (PZT, vertical mode, 0.5MHz resonance frequency), 32 2-comp strain gouges (SGs) for shear strain and 16 1-comp SGs for normal strain measurements, with 48 0.5MHz dynamic SG amplifiers. We also used a 2MN load cell for shear force measurement and three 0.4MN load cells for vertical forces. Data are recorded continuously at an interval of 10MHz for PZT and 1MHz for other sensors. Just after the shear force applied, many stick slip events (SEs) occurred at an interval of a few seconds. By looking carefully at the PZT and SG array data during an SE, we found that one SE consists of many micro stick slip events (MSEs), which can be grouped into two (the former and the latter). These two groups correspond to the acceleration and deceleration stage of the SE. In LB04-005 (6.7MPa normal stress), a clear nucleation phase can be detected that initiated at a narrow area, propagate slowly (~20m/s) and accelerated. Then, a seismic rupture started to propagate at a velocity of ~3km/s (subshear) or ~6.5km/s (supershear). Detailed features are shown in Mizoguchi et al. (this meeting). It should be noted that this seismic rupture initiated at a narrow area inside the nucleation zone and sometimes after a certain amount of time; it does not seem a smooth transition process from the acceleration to the seismic rupture as proposed in Ohnaka and Shen (1999, JGR). In contrast, under low normal stress case (LB04-003, 2.7MPa), there were no visible nucleation phases but a sequence of foreshocks was observed, which was not dominant in LB04-005. The foreshock slip area was typically around 10cm long. Again, we could not see any visible correlation between the location and preceding time of foreshocks and that of seismic rupture initiation. By looking at the fault surface topography that was recorded as photograph images before and after the experiment, in the nucleation zone, grooves are not developed, while outside the nucleation area, grooves are well developed. Grooves are caused by the creation of gouge particles during the sliding. It could be interesting to note that outside the groove, the sliding surface looks very smooth and shiny, indicating that this area was polished but did not create gouge particles. Therefore, we might speculate that this shiny fault area is responsible for the initiation phase and when the stress state becomes critical, seismic rupture starts around one of the grooves. And in LB04-003, the shiny area might not support the shear stress so that the foreshock releases the strain around the grooves.

  3. Proton slip in the ATP synthase of Rhodobacter capsulatus: induction, proton conduction, and nucleotide dependence

    E-print Network

    Steinhoff, Heinz-Jürgen

    Proton slip in the ATP synthase of Rhodobacter capsulatus: induction, proton conduction. Uncoupled proton leakage (slip) has only been observed in chloroplast enzyme at unphysiologically low nucleotide concentration. We investigated the properties of proton slip in chromatophores (sub

  4. Progress in the prevention of falls caused by slipping

    Microsoft Academic Search

    M. TISSERAND

    1985-01-01

    Initial research by the INRS showed the importance of biomechanical factors in the causes of accidents by slipping. Dynamic friction was shown to be far more significant than static fraction. The measuring procedure which has been developed does not provide a model of walking or slipping but a physical measurement giving the same ranking as subject evaluation methods.Systematic measurements show

  5. Continuum mathematical modeling of slip weakening in geological systems

    E-print Network

    Borja, Ronaldo I.

    Continuum mathematical modeling of slip weakening in geological systems Ronaldo I. Borja1 and Craig algorithm for the analysis of prefailure and postfailure responses of geological systems in a boundary value of postfailure behavior. This paper focuses on the narrow time interval of slip weakening, from the moment

  6. Slip Flow Over Structured Surfaces with Entrapped Microbubbles

    Microsoft Academic Search

    Jari Hyväluoma; Jens Harting

    2008-01-01

    On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip

  7. Wall slip and hydrodynamics of two-dimensional journal bearing

    Microsoft Academic Search

    G. J. Ma; C. W. Wu; P. Zhou

    2007-01-01

    In the present paper, based on the limiting shear stress model, a multi-linearity finite element algorithm and quadratic programming technique are used to study the influence of wall slip on the hydrodynamic lubrication performance of a two-dimensional journal bearing (finite length journal bearing). It is found that if the lubricated surfaces are designed as homogeneous slip surfaces, the hydrodynamic force

  8. Development of tactile sensor for detecting contact force and slip

    Microsoft Academic Search

    Byungjune Choi; Hyouk Ryeol Choi; Sungchul Kang

    2005-01-01

    In this paper, a fingertip tactile sensor is presented which can detect contact normal force as well as incipient slip. The sensor, based on polyvinylidene fluoride (PVDF), and pressure variable resistor ink, is physically flexible enough to be deformed into any three-dimensional geometry. In order to detect incipient slip, a PVDF strip is arranged along the direction normal to the

  9. Reinforced Concrete Fiber Beam Element with Bond-Slip

    Microsoft Academic Search

    Giorgio Monti; Enrico Spacone

    2000-01-01

    This paper presents a new reinforced concrete beam finite element that explicitly accounts for the slip between the reinforcing bars and the surrounding concrete. The element formulation combines the fiber- section model with the finite-element model of a reinforcing bar with continuous slip. The section model retains the plane-section assumption, but the steel fiber strains are computed as the sum

  10. Partial slip in mesoscale contacts: dependence on contact size.

    PubMed

    Hanke, Sylvia; Petri, Judith; Johannsmann, Diethelm

    2013-09-01

    Using acoustic resonators, we have studied the occurrence and the magnitude of partial slip between glass spheres and polymer surfaces. The measurement relies on the shifts of resonance frequency and bandwidth, ?f and ??, induced by the contact as well as the dependence of ?f and ?? on the amplitude of oscillation. One often finds a decrease of ?f at elevated amplitudes, which goes back to partial slip (also "microslip"). Building on two different models of partial slip, we derive the frequency-amplitude relation from the force-displacement relation. In accordance with both models, the bandwidth is found to increase with amplitude in the partial slip regime. For the highest amplitudes and largest spheres investigated, one observes a decrease of bandwidth with amplitude, which is interpreted as a transition to gross slip. Deviating from both models of partial slip, ?f is sometimes found to be independent of amplitude in the low-amplitude range. Constant ?f implies linear force-displacement relations. The critical amplitude for the onset of partial slip depends on the contact radius, where partial slip is more pronounced for larger contacts. This finding can be explained by a smooth stress profile at the edge of the contact with no singularity. The stress at the edge might be lowered by nanoscale roughness, by capillary forces, or by the inability of the two surfaces to reestablish a sticking contact at the turning point of the oscillation. PMID:24125277

  11. Rupture Dynamics With Energy Loss Outside the Slip Zone

    Microsoft Academic Search

    D. J. Andrews

    2003-01-01

    Energy loss in a damage zone outside the slip zone contributes to fracture energy. Because the thickness of the damage zone increases with rupture propagation distance, fracture energy increases with earthquake size. A rupture front propagating near its limiting velocity has a stress concentration with large shear components at orientations different from that of the slip zone. These components can

  12. Rupture dynamics with energy loss outside the slip zone

    Microsoft Academic Search

    D. J. Andrews

    2005-01-01

    Energy loss in a fault damage zone, outside the slip zone, contributes to the fracture energy that determines rupture velocity of an earthquake. A nonelastic two-dimensional dynamic calculation is done in which the slip zone is modeled as a fault plane and material off the fault is subject to a Coulomb yield condition. In a mode 2 crack-like solution in

  13. Continuum mathematical modeling of slip weakening in geological systems

    Microsoft Academic Search

    Ronaldo I. Borja; Craig D. Foster

    2007-01-01

    We describe a framework for mathematical modeling of slip weakening in an initially intact rock mass due to shear strain localization along any arbitrary slip plane. The modeling technique considered is based on continuum mechanics and may be cast directly into a standard nonlinear finite element algorithm for the analysis of prefailure and postfailure responses of geological systems in a

  14. The detection of GPS cycle slips based on wavelet transform

    Microsoft Academic Search

    Wang Yong; Guo Zengzhang; Hu Shengwu; Liu Yanping

    2010-01-01

    Accurately detecting and repairing cycle slips is an important pre-processing step in high precision GPS carrier phase positioning and applications. Carrier phase measurements can be divided into high and low frequency components by wavelet transform which wavelet coefficients of local extremum point can be detected phase of the cycle slips. In this paper, wavelet transform is used to detect cycle

  15. Learning and prediction of slip from visual information

    Microsoft Academic Search

    Anelia Angelova; Larry Matthies; Daniel M. Helmick; Pietro Perona

    2007-01-01

    This paper presents an approach for slip prediction from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobility. Therefore, obtaining information about slip before entering such terrain can be very useful for better planning and avoiding these areas. To

  16. Constraining fault constitutive behavior with slip and stress heterogeneity

    Microsoft Academic Search

    B. T. Aagaard; T. H. Heaton

    2008-01-01

    We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2)

  17. Supershear Mach-Waves Expose the Fault Breakdown Slip

    Microsoft Academic Search

    V. M. Cruz-Atienza; K. B. Olsen

    2010-01-01

    During an earthquake, changes in stresses on the fault and within the surrounding material occur as the fault slips and radiates seismic waves. The radiated energy strongly depends on the way these stresses evolve in the rupture front, where most of dissipative mechanisms concentrate. Thus, any constraint obtained from observations on how tractions drop as the fault slips is crucial

  18. Slip ring experience in long duration space applications

    Microsoft Academic Search

    Damon D. Phinney

    1986-01-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use

  19. Theoretical Substantiation of the Slip Index Approach to Fretting

    Microsoft Academic Search

    M. Varenberg; I. Etsion; E. Altus

    2005-01-01

    A theoretical basis is presented for a previous fully empirical development of the unified approach to fretting that was based on a new similarity criterion termed slip index. It is shown that the slip index can be analytically derived from any friction loop geometry and hence, can be used for the characterization of any fretting system.

  20. Slip-compensated path following for planetary exploration rovers

    Microsoft Academic Search

    Daniel M. Helmick; Stergios I. Roumeliotis; Yang Cheng; Daniel S. Clouse; Max Bajracharya; Larry H. Matthies

    2006-01-01

    A system that enables continuous slip compensation for a Mars rover has been designed, imple- mented, and eld-tested. This system is composed of several components that allow the rover to accurately and continuously follow a designated path, compensate for slippage, and reach intended goals in high-slip environments. These components include: visual odometry, vehicle kinematics, a Kalman lter pose estimator, and

  1. Self-healing slip pulse on a frictional surface

    Microsoft Academic Search

    James R. Rice; Gutuan Zheng

    1995-01-01

    Guided by seismic observations of short-duration radiated pulses in earthquake ruptures, Heaton (1990) has postulated a mechanism for the frictional sliding of two identical elastic solids that consists in the subsonic propagation of a self-healing slip velocity pulse of finite duration along the interface. The same type of pulse may be conjectured for inhomogeneous slip along sufficiently large, and compliant,

  2. Large area multiturn superfluid phase slip gyroscope Niels Brucknera)

    E-print Network

    Packard, Richard E.

    Large area multiturn superfluid phase slip gyroscope Niels Brucknera) and Richard Packard 15 November 2002 We have built and tested a large area multiturn superfluid 4 He phase slip gyroscope-of-principle model, with an improvement in sensitivity of 20 over any other superfluid 4 He gyroscope. We find

  3. Enhanced slip control performance using nonlinear passive suspension system

    Microsoft Academic Search

    Samuel John; Jimoh O. Pedro; Claudiu R. Pozna

    2011-01-01

    Antilock Brake System (ABS) controller maintains or controls the slip between tyre and road to maximize the braking torque to achieve a shorter braking distance and control of the steering wheel. This paper presents a PID slip controller performance that incorporates nonlinear passive suspension dynamics. Three scenarios were compared The first scenario is the performance of the controller in a

  4. Effective slip over superhydrophobic surfaces in thin channels

    E-print Network

    Feuillebois, François; Vinogradova, Olga I

    2008-01-01

    Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a micro- and nanoscopic texture. Recent work has focused on specific cases, such as striped grooves or arrays of pillars, with limited theoretical guidance. Here, we consider the experimentally relevant limit of thin channels and obtain rigorous bounds on the effective slip length for any two-component (e.g. low-slip and high-slip) texture with given area fractions. Among all anisotropic textures, parallel stripes attain the largest (or smallest) possible slip in a straight, thin channel for parallel (or perpendicular) orientation with respect to the mean flow. For isotropic (e.g. chessboard or random) textures, the Hashin-Strikman conditions further constrain the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces.

  5. Learning and Prediction of Slip from Visual Information

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Matthies, Larry; Helmick, Daniel; Perona, Pietro

    2007-01-01

    This paper presents an approach for slip prediction from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobility. Therefore, obtaining information about slip before entering such terrain can be very useful for better planning and avoiding these areas. To address this problem, terrain appearance and geometry information about map cells are correlated to the slip measured by the rover while traversing each cell. This relationship is learned from previous experience, so slip can be predicted remotely from visual information only. The proposed method consists of terrain type recognition and nonlinear regression modeling. The method has been implemented and tested offline on several off-road terrains including: soil, sand, gravel, and woodchips. The final slip prediction error is about 20%. The system is intended for improved navigation on steep slopes and rough terrain for Mars rovers.

  6. Formation of Quantum Phase Slip Pairs in Superconducting Nanowires

    NASA Astrophysics Data System (ADS)

    Belkin, A.; Belkin, M.; Vakaryuk, V.; Khlebnikov, S.; Bezryadin, A.

    2015-04-01

    Macroscopic quantum tunneling is a fundamental phenomenon of quantum mechanics related to the actively debated topic of quantum-to-classical transition. The ability to realize macroscopic quantum tunneling affects implementation of qubit-based quantum computing schemes and their protection against decoherence. Decoherence in qubits can be reduced by means of topological protection, e.g., by exploiting various parity effects. In particular, paired phase slips can provide such protection for superconducting qubits. Here, we report on the direct observation of quantum paired phase slips in thin-wire superconducting loops. We show that in addition to conventional single phase slips that change the superconducting order parameter phase by 2 ? , there are quantum transitions that change the phase by 4 ? . Quantum paired phase slips represent a synchronized occurrence of two macroscopic quantum tunneling events, i.e., cotunneling. We demonstrate the existence of a remarkable regime in which paired phase slips are exponentially more probable than single ones.

  7. Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers

    NASA Astrophysics Data System (ADS)

    Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

    2013-03-01

    This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, ??max-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

  8. Rock mechanics. Superplastic nanofibrous slip zones control seismogenic fault friction.

    PubMed

    Verberne, Berend A; Plümper, Oliver; de Winter, D A Matthijs; Spiers, Christopher J

    2014-12-12

    Understanding the internal mechanisms controlling fault friction is crucial for understanding seismogenic slip on active faults. Displacement in such fault zones is frequently localized on highly reflective (mirrorlike) slip surfaces, coated with thin films of nanogranular fault rock. We show that mirror-slip surfaces developed in experimentally simulated calcite faults consist of aligned nanogranular chains or fibers that are ductile at room conditions. These microstructures and associated frictional data suggest a fault-slip mechanism resembling classical Ashby-Verrall superplasticity, capable of producing unstable fault slip. Diffusive mass transfer in nanocrystalline calcite gouge is shown to be fast enough for this mechanism to control seismogenesis in limestone terrains. With nanogranular fault surfaces becoming increasingly recognized in crustal faults, the proposed mechanism may be generally relevant to crustal seismogenesis. PMID:25504714

  9. Quantifying effective slip length over micropatterned hydrophobic surfaces

    E-print Network

    Tsai, Peichun; Pirat, Christophe; Wessling, Matthias; Lammertink, Rob G H; Lohse, Detlef

    2009-01-01

    We employ micro-particle image velocimetry ($\\mu$-PIV) to investigate laminar micro-flows in hydrophobic microstructured channels, in particular the slip length. These microchannels consist of longitudinal micro-grooves, which can trap air and prompt a shear-free boundary condition and thus slippage enhancement. Our measurements reveal an increase of the slip length when the width of the micro-grooves is enlarged. The result of the slip length is smaller than the analytical prediction by Philip et al. [1] for an infinitely large and textured channel comprised of alternating shear-free and no-slip boundary conditions. The smaller slip length (as compared to the prediction) can be attributed to the confinement of the microchannel and the bending of the meniscus (liquid-gas interface). Our experimental studies suggest that the curvature of the meniscus plays an important role in microflows over hydrophobic micro-ridges.

  10. Premonitory slip and tidal triggering of earthquakes

    USGS Publications Warehouse

    Lockner, D.A.; Beeler, N.M.

    1999-01-01

    We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10-4 and 10-6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sources. The period of the modulating signal ranged from 10 to 10,000 s. For each combination of amplitude and period of the modulating signal, multiple stick-slip events were recorded to determine the degree of correlation between the timing of simulated earthquakes and the imposed periodic loading function. Over the range of parameters studied, the degree of correlation of earthquakes was most sensitive to the amplitude of the periodic loading, with weaker dependence on the period of oscillations and the average loading rate. Accelerating premonitory slip was observed in these experiments and is a controlling factor in determining the conditions under which correlated events occur. In fact, some form of delayed failure is necessary to produce the observed correlations between simulated earthquake timing and characteristics of the periodic loading function. The transition from strongly correlated to weakly correlated model earthquake populations occurred when the amplitude of the periodic loading was approximately 0.05 to 0.1 MPa shear stress (0.03 to 0.06 MPa Coulomb failure function). Lower-amplitude oscillations produced progressively lower correlation levels. Correlations between static stress increases and earthquake aftershocks are found to degrade at similar stress levels. Typical stress variations due to Earth tides are only 0.001 to 0.004 MPa, so that the lack of correlation between Earth tides and earthquakes is also consistent with our findings. A simple extrapolation of our results suggests that approximately 1% of midcrustal earthquakes should be correlated with Earth tides. Triggered seismicity has been reported resulting from the passage of surface waves excited by the Landers earthquake. These transient waves had measured amplitudes in excess of 0.1 MPa at frequencies of 0.05 to 0.2 Hz in regions of notable seismicity increase. Similar stress oscillations in our laboratory experiments produced strongly correlated stick-slip events. We suggest that seemingly inconsistent natural observations of triggered seismicity and absence of tidal triggering indicate that failure is amplitude and frequency dependent. This is the expected result if, as in our laboratory experiments, the rheology of the Earth's crust permits delayed failure.

  11. The joint intersection probability

    Microsoft Academic Search

    Y. H. Hatzor; A. Feintuch

    2005-01-01

    In this paper a practical method to apply block theory is presented. Block theory provides the removable joint pyramids from a given free surface regardless of the number of joints in any joint intersection. While robust, the application of the theory in real practice is hampered by the large outcome space of possibly removable joint pyramids consisting of k mutually

  12. Constraining fault constitutive behavior with slip and stress heterogeneity

    USGS Publications Warehouse

    Aagaard, B.T.; Heaton, T.H.

    2008-01-01

    We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2) maintain these conditions following rupture, so that the stress field is compatible with the generation of aftershocks and facilitates heterogeneous slip in subsequent events. Our three-dimensional fmite element simulations of magnitude 7 events on a vertical, planar strike-slip fault show that the conditions that lead to slip heterogeneity remain in place after large events when the dynamic stress drop (initial shear stress) and breakdown work (fracture energy) are spatially heterogeneous. In these models the breakdown work is on the order of MJ/m2, which is comparable to the radiated energy. These conditions producing slip heterogeneity also tend to produce narrower slip pulses independent of a slip rate dependence in the fault constitutive model. An alternative mechanism for generating these confined slip pulses appears to be fault constitutive models that have a stronger rate dependence, which also makes them difficult to implement in numerical models. We hypothesize that self-consistent ruptures could also be produced by very narrow slip pulses propagating in a self-sustaining heterogeneous stress field with breakdown work comparable to fracture energy estimates of kJ/M2. Copyright 2008 by the American Geophysical Union.

  13. SlipChip for immunoassays in nanoliter volumes

    PubMed Central

    Liu, Weishan; Chen, Delai; Du, Wenbin; Nichols, Kevin P.; Ismagilov, Rustem F.

    2010-01-01

    This paper describes a SlipChip-based approach to perform bead-based heterogeneous immunoassays with multiple nanoliter-volume samples. As a potential device to analyze the output of the chemistrode, the performance of this platform was tested using low concentrations of biomolecules. Two strategies to perform the immunoassay in the SlipChip were tested: 1) a unidirectional slipping method to combine the well containing a sample with a series of wells preloaded with reagents; 2) a back-and-forth slipping method to introduce a series of reagents to a well containing the sample by reloading and slipping the well containing the reagent. The SlipChips were fabricated with hydrophilic surfaces on the interior of the wells and with hydrophobic surfaces on the face of the SlipChip to enhance filling, transferring, and maintaining aqueous solutions in shallow wells. Nanopatterning was used to increase the hydrophobic nature of the SlipChip surface. Magnetic beads containing the capture antibody were efficiently transferred between wells and washed by serial dilution. An insulin immunoenzymatic assay showed a detection of limit of ~13 pM. Forty eight droplets of nanoliter volume were analyzed in parallel, including an on-chip calibration. The design of the SlipChip is flexible to accommodate other types of immunoassays, both heterogeneous and homogeneous. This work establishes the possibility of using SlipChip-based immunoassays in small volumes for a range of possible applications, including analysis of plugs from a chemistrode, detection of molecules from single cells, and diagnostic monitoring. PMID:20334360

  14. Local tsunamis and distributed slip at the source

    USGS Publications Warehouse

    Geist, E.L.; Dmowska, R.

    1999-01-01

    Variations in the local tsunami wave field are examined in relation to heterogeneous slip distributions that are characteristic of many shallow subduction zone earthquakes. Assumptions inherent in calculating the coseismic vertical displacement field that defines the initial condition for tsunami propagation are examined. By comparing the seafloor displacement from uniform slip to that from an ideal static crack, we demonstrate that dip-directed slip variations significantly affect the initial cross-sectional wave profile. Because of the hydrodynamic stability of tsunami wave forms, these effects directly impact estimates of maximum runup from the local tsunami. In most cases, an assumption of uniform slip in the dip direction significantly underestimates the maximum amplitude and leading wave steepness of the local tsunami. Whereas dip-directed slip variations affect the initial wave profile, strike-directed slip variations result in wavefront-parallel changes in amplitude that are largely preserved during propagation from the source region toward shore, owing to the effects of refraction. Tests of discretizing slip distributions indicate that small fault surface elements of dimensions similar to the source depth can acceptably approximate the vertical displacement field in comparison to continuous slip distributions. Crack models for tsunamis generated by shallow subduction zone earthquakes indicate that a rupture intersecting the free surface results in approximately twice the average slip. Therefore, the observation of higher slip associated with tsunami earthquakes relative to typical subduction zone earthquakes of the same magnitude suggests that tsunami earthquakes involve rupture of the seafloor, whereas rupture of deeper subduction zone earthquakes may be imbedded and not reach the seafloor.

  15. Preslip and cascade processes initiating laboratory stick slip

    NASA Astrophysics Data System (ADS)

    McLaskey, Gregory C.; Lockner, David A.

    2014-08-01

    Recent modeling studies have explored whether earthquakes begin with a large aseismic nucleation process or initiate dynamically from the rapid growth of a smaller instability in a "cascade-up" process. To explore such a case in the laboratory, we study the initiation of dynamic rupture (stick slip) of a smooth saw-cut fault in a 76 mm diameter cylindrical granite laboratory sample at 40-120 MPa confining pressure. We use a high dynamic range recording system to directly compare the seismic waves radiated during the stick-slip event to those radiated from tiny (M -6) discrete seismic events, commonly known as acoustic emissions (AEs), that occur in the seconds prior to each large stick slip. The seismic moments, focal mechanisms, locations, and timing of the AEs all contribute to our understanding of their mechanics and provide us with information about the stick-slip nucleation process. In a sequence of 10 stick slips, the first few microseconds of the signals recorded from stick-slip instabilities are nearly indistinguishable from those of premonitory AEs. In this sense, it appears that each stick slip begins as an AE event that rapidly (~20 µs) grows about 2 orders of magnitude in linear dimension and ruptures the entire 150 mm length of the simulated fault. We also measure accelerating fault slip in the final seconds before stick slip. We estimate that this slip is at least 98% aseismic and that it both weakens the fault and produces AEs that will eventually cascade-up to initiate the larger dynamic rupture.

  16. Floor/shoe slip resistance measurement.

    PubMed

    Chaffin, D B; Woldstad, J C; Trujillo, A

    1992-05-01

    A variety of slip measurement devices exist that provide estimates of both static and dynamic coefficient-of-friction (COF) values between one's shoes and the floor. Unfortunately, different shoe sole/heel materials, floor conditions, and contaminants will affect the tests in ways that result in widely varying COF estimates. This paper reviews the basic physics of such tests and describes a set of experiments to determine the static and dynamic COF values under operating conditions known to exist in different jobs. The results define a set of conditions wherein low (hazardous) COF values would exist (e.g., hard Neolite shoe material in contact with a wet, smooth walking surface). The results also question the use of light-load testing devices and static and slow speed reference COF values in the literature. PMID:1609738

  17. Synchronization of coupled stick-slip oscillators

    NASA Astrophysics Data System (ADS)

    Sugiura, N.; Hori, T.; Kawamura, Y.

    2014-02-01

    A rationale is provided for the emergence of synchronization in a system of coupled oscillators in a stick-slip motion. The single oscillator has a limit cycle in a region of the state space for each parameter set beyond the supercritical Hopf bifurcation. The two-oscillator system that has similar weakly coupled oscillators exhibits synchronization in a parameter range. The synchronization has an anti-phase nature for an identical pair. However, it tends to be more in-phase for a non-identical pair with a rather weak coupling. A system of three identical oscillators (1, 2, and 3) coupled in a line (with two springs k12=k23) exhibits synchronization with two of them (1 and 2 or 2 and 3) being nearly in-phase. These collective behaviours are systematically estimated using the phase reduction method.

  18. Rover Slip Validation and Prediction Algorithm

    NASA Technical Reports Server (NTRS)

    Yen, Jeng

    2009-01-01

    A physical-based simulation has been developed for the Mars Exploration Rover (MER) mission that applies a slope-induced wheel-slippage to the rover location estimator. Using the digital elevation map from the stereo images, the computational method resolves the quasi-dynamic equations of motion that incorporate the actual wheel-terrain speed to estimate the gross velocity of the vehicle. Based on the empirical slippage measured by the Visual Odometry software of the rover, this algorithm computes two factors for the slip model by minimizing the distance of the predicted and actual vehicle location, and then uses the model to predict the next drives. This technique, which has been deployed to operate the MER rovers in the extended mission periods, can accurately predict the rover position and attitude, mitigating the risk and uncertainties in the path planning on high-slope areas.

  19. Loading and texture bias on the competitive slip activity for basal and prismatic slip systems in HCP alloys

    NASA Astrophysics Data System (ADS)

    Saxena, A. K.; Tewari, A.; Pant, P.

    2015-04-01

    Asymmetry in hexagonal crystal structure makes the occurrence of slip strongly dependent on the texture of sample. In titanium, which has a c/a ratio less than ideal, slip occurs preferentially on prismatic slip system. However other slip systems may get activated depending on the resolved shear stresses. In this paper we present results from plane strain compression experiments where the same area of the sample was imaged before and after deformation to document changes in microstructure. We then compare these results with a simple calculation of plastic strain based on activation of various slip systems depending on their respective critical resolved shear stresses. We show that incorporation of a strain rate dependent hardening parameter provides a reasonable match with the experimentally observed deformation behaviour of various grain orientations.

  20. A simple stick-slip and creep-slip model for repeating earthquakes and its implication for microearthquakes at Parkfield

    USGS Publications Warehouse

    Beeler, N.M.; Lockner, D.L.; Hickman, S.H.

    2001-01-01

    If repeating earthquakes are represented by circular ruptures, have constant stress drops, and experience no aseismic slip, then their recurrence times should vary with seismic moment as tr ?? Mo1/3. In contrast, the observed variation for small, characteristic repeating earthquakes along a creeping segment of the San Andreas fault at Parkfield (Nadeau and Johnson, 1998) is much weaker. Also, the Parkfield repeating earthquakes have much longer recurrence intervals than expected if the static stress drop is 10 MPa and if the loading velocity VL is assumed equal to the geodetically inferred slip rate of the fault Vf. To resolve these discrepancies, previous studies have assumed no aseismic slip during the interseismic period, implying either high stress drop or VL ??? Vf. In this study, we show that a model that includes aseismic slip provides a plausible alternative explanation for the Parkfield repeating earthquakes. Our model of a repeating earthquake is a fixed-area fault patch that is allowed to continuously creep and strain harden until reaching a failure threshold stress. The strain hardening is represented by a linear coefficient C, which when much greater than the elastic loading stiffness k leads to relatively small interseismic slip (stick-slip). When C and k are of similar size creep-slip occurs, in which relatively large aseismic slip accrues prior to failure. Because fault-patch stiffness varies with patch radius, if C is independent of radius, then the model predicts that the relative amount of seismic to total slip increases with increasing radius or Mo, consistent with variations in slip required to explain the Parkfield data. The model predicts a weak variation in tr with Mo similar to the Parkfield data.

  1. Nanocrystalline mirror-slip surfaces in calcite gouge sheared at sub-seismic slip rates

    NASA Astrophysics Data System (ADS)

    Verberne, B. A.; Plümper, O.; de Winter, D.; Niemeijer, A. R.; Spiers, C. J.

    2013-12-01

    If seismic-aseismic transitions in fault rocks are to be recognized from microstructures preserved in natural fault rocks, an understanding of the microphysical mechanisms that produce such microstructures is needed. We report on microstructures recovered from dry direct shear experiments on (simulated) dry calcite gouge, performed at 50 MPa normal stress, 18-150°C and low sliding velocities (0.1-10 ?m/s). The mechanical data show a transition from velocity strengthening below ~80°C to velocity weakening slip at higher temperatures. We investigated both loose gouge fragments and thin sections, characterizing the microstructures at the mm- to nm-scales. All deformed samples split along a shear band fabric defined by mainly R1- and boundary shears. Viewed normal to the shear plane, these bands commonly showed shiny, elongate patches aligned, and striated, parallel to the shear direction. These patches were especially common in samples tested below 80°C, though shear band splitting was less well-developed above 80°C so that even if the shiny patches formed at higher temperature they were less frequently exposed. Scanning Electron Microscopy (SEM) applied to shiny patches formed in samples sheared at room temperature showed the presence of elongate, streaked out sub-micron-sized particles oriented parallel to the shear direction. Transmitted light optical microscopy of thin sections cut normal to the shear plane and parallel to the shear direction, combined with Focused Ion Beam (FIB) - SEM on loose gouge fragments, showed that the shiny surfaces correspond with shear bands characterized by extreme grain size reduction and sintered sub-micron-particles. Transmission Electron Microscopy (TEM) further revealed that the cores of the shear bands consist of nanocrystallites some 20 nm in size, with a Crystallographic Preferred Orientation (CPO). Our results demonstrate that mirror-like nanocrystalline slip zones can form in calcite gouge sheared at shallow crustal conditions at sub-seismic sliding velocities, in velocity strengthening as well as velocity weakening samples. This means that their presence cannot be used as a single diagnostic indicator for seismic slip in natural fault rocks. Our SEM and TEM observations suggest that, at room temperature, the frictional behavior of the shear bands is dominated by crystal plastic plus nanogranular flow mechanisms, rather than by brittle deformation processes - as inferred for frictional slip in some metals. We further suggest that it is the thermally activated nature of crystal plasticity that is responsible for the transition from velocity strengthening to velocity weakening slip that we observed at ~80°C. The inferred mechanism has important implications for understanding both the depth range of seismicity and the seismic cycle in tectonically-active carbonate terrains.

  2. Predicting slips and falls considering required and available friction.

    PubMed

    Hanson, J P; Redfern, M S; Mazumdar, M

    1999-12-01

    This study investigated the relationship among measurements of friction, the biomechanics of gait, and actual slip and fall events. The goal was to develop a method for estimating the probability of slips and falls based on measurements of available friction and required friction. Five subjects wearing safety harnesses walked down a ramp at various angles with either a tile or carpeted surface under dry, wet or soapy conditions. Ramp angles of 0 degree, 10 degrees and 20 degrees were used to vary the shear and normal foot force requirements. The dynamic coefficient of friction (DCOF) of shoe, floor surface and contaminant interfaces was measured. Required friction was assessed by examining the foot forces during walking trials when no slips occurred. Slips with recoveries and slips resulting in falls were recorded and categorized using a force plate and high-speed video camera. These data were then incorporated into a logistic regression to model the probability of a slip or fall event occurring based on the difference between the COF required by the foot forces generated and the measured DCOF. The results showed that the number of slip and fall events increased as the difference between the required COF and the measured DCOF increased. The logistic regression model fit the data well, resulting in an estimate of the probability of a slip or fall event based on the difference between the measured and required friction. This type of model could be used in the future to evaluate slip resistance measurement devices under various environments and assist in the design of safer work environments. PMID:10643404

  3. Interfacial instability of compressible slip flows in a microchannel.

    PubMed

    He, Andong

    2013-05-01

    In microfluidics the instability of an interface between two fluids may be favorable or unfavorable. Such an instability for incompressible flows has been extensively studied in the literature; in this paper we extend it to compressible flows which slip on the solid boundary. A generalized Darcy's law taking into consideration the compressibility and velocity slip is obtained. Using a conformal-mapping method we derive an interface equation on a fixed domain, the solutions of which determine the moving interface. We also examine the linear stability of the base-state flow by perturbing the corresponding conformal map and show that the velocity slip has a stabilizing effect. PMID:23767619

  4. Finite fault modeling of oceanic strike-slip earthquakes

    NASA Astrophysics Data System (ADS)

    Aderhold, K.; Abercrombie, R. E.

    2014-12-01

    The depth extent of seismic rupture in oceanic lithosphere is thought to be limited by the 600º to 800ºC isotherm with the thermal structure generally characterized by a half-space cooling model. However, previous studies constraining this limit represent a limited number of individual faults and earthquakes and use a wide range of different methods. Observations of significantly deep slip at the 800ºC isotherm, supershear rupture velocities, and along-strike differences in seismic slip have been made for oceanic strike slip earthquakes (McGuire and Beroza, 2012; Yue et al., 2013; McGuire et al., 2012). To examine how seismic rupture is controlled, we look at a variety of earthquakes in different settings using the same method of finite fault modeling. We choose the largest and best recorded oceanic strike-slip earthquakes from tectonic settings of interplate transform, intraplate fracture zones, and strike-slip plate boundaries. These earthquakes are located in the Indian Ocean, near the South Sandwich Islands, on the edge of the Scotia Plate, off the coast of Alaska, and west of Australia, rupturing lithosphere with ages from 0 to 70 My. We first determine first motion and point source mechanisms from the first arriving P waves and later arriving pP, sP, and SH waves. Using the nodal planes of these mechanisms, we perform finite fault modeling at a range of constant rupture velocities and hypocenter depths. We determine which slip asperities are well-constrained by limiting the extent of the preferred model until the fit to the data is affected significantly. The rupture directivity, rupture speed, depth extent of slip, and along-strike distribution of slip is then compared between events to identify relationships to the tectonic setting, thermal structure inferred from lithospheric age, or other possible mechanisms for controlling slip. These strike-slip earthquakes also provide examples of rupture along a bimaterial fault plane, which have been shown to have a relationship between stress loading direction, rupture directivity, and rupture speed by previous studies. The results of this study will determine seismic slip distribution in the relatively simple structure of oceanic lithosphere, and provide a comparison for the more complex structure of continental strike-slip faults.

  5. Simulations of slip flow on nanobubble-laden surfaces

    NASA Astrophysics Data System (ADS)

    Hyväluoma, J.; Kunert, C.; Harting, J.

    2011-05-01

    On microstructured hydrophobic surfaces, geometrical patterns may lead to the appearance of a superhydrophobic state, where gas bubbles at the surface can have a strong impact on the fluid flow along such surfaces. In particular, they can strongly influence a detected slip at the surface. We present two-phase lattice Boltzmann simulations of a flow over structured surfaces with attached gas bubbles and demonstrate how the detected slip depends on the pattern geometry, the bulk pressure, or the shear rate. Since a large slip leads to reduced friction, our results give assistance in the optimization of microchannel flows for large throughput.

  6. The Frictional Proprierties of Dolomite Gouges at Subseismic Slip Rates

    NASA Astrophysics Data System (ADS)

    Faoro, I.; De Paola, N.

    2011-12-01

    Field studies conducted on the slip zones of exhumed faults, developed in the same evaporitic sequences as the seismic sources of the Colfiorito earthquakes, suggest that localized slip occurred within narrow (<5mm) principal slip zones of fine-grained dolomite and Mg-rich calcite fault gouges. These are characterized by thin slip planes of localized deformation (500 micron). Recent friction experiments performed on dolomite gouge samples at seismic slip rates have shown a dramatic drop of frictional strength (f = 0.1-0.2) from the initial peak values in the Byerlee's range (f = 0.65-0.8). Despite these laboratory data supporting dynamic lubrication of experimental faults at seismic slip rates, the frictional properties and behaviour of dolomite at subseismic slip rates are still poorly understood. We performed a set of preliminary experiments at room temperature and humidity conditions with a low to high velocity rotary shear friction apparatus to investigate the frictional properties and mechanical behaviour of dolomite gouges deforming at sub-seismic slip rates. The gouge samples have been tested at slip rates comprised between 13.4 microns/s to 1.34 mm/s and normal stresses ranging between 2 and 20 MPa. At these sub-seismic slip rates dolomite gouges display strain hardening behaviour during experiments performed at constant slip rate and normal load. During cyclic slide-hold-slide experiments, the magnitude of strain hardening decreases for increasing number of the slide-hold-slide cycles, for a given hold time. This behaviour is particularly evident at the highest normal loads, where the dolomite shows almost strain neutral behaviour during the last cycles, i.e. peak friction is almost absent. Preliminary results during velocity steps experiments show velocity strengthening behaviour at all conditions. A set of preliminary experiments performed on dolomite gouges deformed against host blocks with different roughness shows that the frictional behaviour (strain hardening and velocity strengthening) is not controlled by the surface roughness, although the steady state values of friction coefficients are very small (f = 0.3-0.4) when sliding occurs against polished blocks, with virtually no roughness. This may be due to early slip localization at the gouge host block interface.

  7. Geometry, kinematics and slip rate along the Mosha active fault, Central Alborz, Iran

    NASA Astrophysics Data System (ADS)

    Ritz, J.-F.; Pics Geological Team

    2003-04-01

    The Mosha fault is one of the major active fault in Central Alborz as shown by its strong historical seismicity and its clear morphological signature. Situated at the vicinity of Tehran city, this ~150 km long ~N100°E trending fault represents an important potential seismic source that threatens the Iranian metropolis. In the framework of an Iranian-French joint research program (PICS) devoted to seismic hazard assessment in the Tehran region, we undertook a morphotectonic (determination of the cumulative displacements and the ages of offset morphologic markers) and paleoseismic (determination of the ages and magnitudes of ancient events) study along the Mosha fault. Our objectives are the estimation of the long-term slip rate (Upper Pleistocene-Holocene) and the mean recurrence interval of earthquakes along the different segments of the fault. Our investigations within the Tar Lake valley, along the eastern part of the fault potentially the site of the 1665 (VII, 6.5) historical earthquake - allows us to calculate a preliminary 2 ± 0.1 mm/yr minimum left lateral slip rate. If we assume a characteristic coseismic average displacement comprised between 0.35 m (Mw 6.5) and 1.2 m (Mw 7.1) calculated from Wells &Coppersmith’s functions (1994) and taking the moment magnitudes attributed to the 1665 and 1830 earthquakes (e.g. Berberian &Yeats, 2001) the mean maximum recurrence intervals along this segment of the Mosha fault are comprised between 160 and 620 yrs.

  8. Treatment of slipped capital femoral epiphysis with a cannulated-screw technique.

    PubMed

    Koval, K J; Lehman, W B; Rose, D; Koval, R P; Grant, A; Strongwater, A

    1989-10-01

    Sixty patients (eighty hips) who had slipped capital femoral epiphysis were treated by epiphyseodesis with a cannulated-screw technique. Forty-nine patients (sixty-seven hips) were available for follow-up, forty-four (sixty hips) of whom were followed for a minimum of two years. Thirty-five patients (forty-six hips) were followed until the hardware was removed. Of seventy-two hips in which contrast medium was injected, arthrographic results were obtained in three. In these three hips, there was evidence of pre-existing narrowing of the joint space. Four patients (six hips) who did not have evidence of penetration by a screw or guide-wire had evidence of either pre-existing chondrolysis or osteoarthrosis. Chondrolysis did not develop postoperatively in any patient who had no evidence of it preoperatively. PMID:2793890

  9. Spatiotemporal slip distributions of three long-term slow slip events beneath the Bungo Channel, southwest Japan, inferred from inversion analyses of GPS data

    NASA Astrophysics Data System (ADS)

    Yoshioka, Shoichi; Matsuoka, Yoshiko; Ide, Satoshi

    2015-06-01

    We estimated spatiotemporal slip distributions from three long-term slow slip events (L-SSEs) that occurred beneath the Bungo Channel at the convergent plate boundary between the subducting oceanic Philippine Sea plate and the continental Amurian plate in southwest Japan between 1997 and 1998, 2002 and 2004 and 2009 and 2011. For this purpose, we employed an inversion method using a Bayesian Information Criterion (ABIC), which included the following three prior constraints: the spatial slip distribution was smooth to some extent, slip directions were mostly oriented in the direction of plate convergence and the temporal change in slip was smooth to some extent. Our results revealed that the three L-SSEs had a common feature: slipped regions expanded southwestward at accelerating slip velocities. We also found that major slipped regions migrated southwestward by approximately 50-100 km yr-1. In contrast, southwestward and northeastward migration of the slipped regions, whose direction differed from event to event, was also identified before or after the periods when the slip velocities were at their greatest. Comparing the obtained spatiotemporal slip distributions of the three L-SSEs with slip-deficit rate distributions obtained in our previous study, we investigated the accumulation process of the slip deficit caused by slip-deficit rate distributions and the release processes of the slip deficit caused by the obtained spatiotemporal slip distributions of the three L-SSEs. At the western plate interface of the Bungo Channel, as the slip-deficit rate was small and the amounts of slips associated with the three L-SSEs were large, most of the accumulated slip deficit was estimated to have been released. In contrast, at the eastern plate interface, as the slip-deficit rate was large and the amounts of slips associated with the three L-SSEs were small, the slip deficit was estimated to have accumulated effectively. These results suggest that the slipped regions of the three L-SSEs and the strongly coupled region are not spatially complementary; the accumulated slip deficit showed spatial variation even at approximately the same depth range along the arc.

  10. Slip casting and pressure slip casting of Si{sub 3}N{sub 4} aqueous suspensions

    SciTech Connect

    Castanho, S.M. [Institut Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil); Moreno, R. [Instituto de Ceramica y Vidrio, Madrid (Spain); Salomoni, A.; Stamenkovic, I. [Italian Ceramic Center, Bologna (Italy)

    1995-09-01

    The stability of silicon nitride aqueous slips has been studied in order to obtain Si{sub 3}N{sub 4} pressureless sintered compacts. High solid content slips (up to 65 wt%) have been prepared by using tetramethylammonium hydroxide as dispersing agent. The effect of sintering aids on the rheology and casting conditions has been studied by slip casting and uniaxial pressure filtration. The casting rate, the green density and the microstructure of samples obtained from both slurry consolidation techniques have been compared taking into account the role of the sintering additives. Sintering of cast green specimens has been performed at 1750{degrees}C in N{sub 2} atmosphere.

  11. Cam deformity and hip degeneration are common after fixation of a slipped capital femoral epiphysis

    PubMed Central

    Klit, Jakob; Gosvig, Kasper; Magnussen, Erland; Gelineck, John; Kallemose, Thomas; Søballe, Kjeld; Troelsen, Anders

    2014-01-01

    Background and purpose — Slipped capital femoral epiphysis is thought to result in cam deformity and femoroacetabular impingement. We examined: (1) cam-type deformity, (2) labral degeneration, chondrolabral damage, and osteoarthritic development, and (3) the clinical and patient-reported outcome after fixation of slipped capital femoral epiphysis (SCFE). Methods — We identified 28 patients who were treated with fixation of SCFE from 1991 to 1998. 17 patients with 24 affected hips were willing to participate and were evaluated 10–17 years postoperatively. Median age at surgery was 12 (10–14) years. Clinical examination, WOMAC, SF-36 measuring physical and mental function, a structured interview, radiography, and MRI examination were conducted at follow-up. Results — Median preoperative Southwick angle was 22o (IQR: 12–27). Follow-up radiographs showed cam deformity in 14 of the 24 affected hips and a Tönnis grade > 1 in 1 affected hip. MRI showed pathological alpha angles in 15 affected hips, labral degeneration in 13, and chondrolabral damage in 4. Median SF-36 physical score was 54 (IQR: 49–56) and median mental score was 56 (IQR: 54–58). These scores were comparable to those of a Danish population-based cohort of similar age and sex distribution. Median WOMAC score was 100 (IQR: 84–100). Interpretation — In 17 patients (24 affected hips), we found signs of cam deformity in 18 hips and early stages of joint degeneration in 10 hips. Our observations support the emerging consensus that SCFE is a precursor of cam deformity, FAI, and joint degeneration. Neither clinical examination nor SF-36 or WOMAC scores indicated physical compromise. PMID:25175666

  12. A Predictive Model for Slip Resistance Using Artificial Neural Networks Janet M. Twomey, IIE Student Member

    E-print Network

    Smith, Alice E.

    conditions. These slip resistance measurements are used by industry, shoe/floor manufacturers and the legal) as measured by a slip resistance testing device. The model predicts the DCOF as a function of six independent]. Prevention of slips has focused on designing the flooring environment to be "slip resistant." This becomes

  13. THE AFFECTS OF FLOOR WEAR ON SLIP RESISTANCE MESAUREMENTS (A PILOT STUDY)

    Microsoft Academic Search

    William A. Mecham; Richard F. Sesek

    An examination of how the normal surface wear on vinyl tiles affects slip resistance measurements. Statistical comparisons are made between slip resistance measurements made with normal pedestrian traffic flow, across normal pedestrian traffic flow, and between high and low wear areas. The results found significant differences between direction of slip resistant measurement and differences in slip resistance with the amount

  14. Shear rate threshold for the boundary slip in dense polymer films Nikolai V. Priezjev

    E-print Network

    Priezjev, Nikolai V.

    transition from no-slip to steady-state slip flow is associated with faster relaxation of the polymer chainsShear rate threshold for the boundary slip in dense polymer films Nikolai V. Priezjev Department; published 24 September 2009 The shear rate dependence of the slip length in thin polymer films confined

  15. Slip-related muscle activation patterns in the stance leg during walking

    Microsoft Academic Search

    April J. Chambers; Rakié Cham

    2007-01-01

    Falls precipitated by slipping are a serious public health concern especially in the elderly. Muscular responses generated during slipping have not been investigated during gait on contaminated floors. This study compared slip-related muscular responses (reactive and proactive) in young and older adults and examined if characteristics of muscular activation patterns during normal gait impact slip severity on contaminated floors. Electromyographic

  16. Slip due to surface roughness for a Newtonian liquid in a viscous microscale disk pump

    Microsoft Academic Search

    Phil Ligrani; Danny Blanchard; Bruce Gale

    2010-01-01

    In the present study, hydrophobic roughness is used to induce near-wall slip in a single rotating-disk micropump operating with Newtonian water. The amount of induced slip is altered by employing different sizes of surface roughness on the rotating disk. The magnitudes of slip length and slip velocities increase as the average size of the surface roughness becomes larger. In the

  17. Variation in slip on intersecting normal faults: Implications for paleostress inversion

    Microsoft Academic Search

    Laurent Maerten

    2000-01-01

    Numerical models based on linear elasticity theory predict asymmetric slip distribution with a steep slip gradient near the line of intersection of intersecting normal faults. They also predict a discrepancy between the direction of slip on the fault plane and the direction of resolved shear stress. Both variations in slip magnitude and direction are due to mechanical interaction between the

  18. Slip modelling, detection and control for redundantly actuated wheeled mobile robots

    Microsoft Academic Search

    Yuan Ping Li; Marcelo H. Ang Jr; Wei Lin

    2008-01-01

    This paper presents a comprehensive methodology (modelling, detection, and control) for tackling slip problems in redundantly actuated wheeled mobile robots. A new concept, ldquoslip velocityrdquo, is introduced for the purpose of enlarging the robotspsila kinematic model by including slip modelling. Our simple and yet effective slip detection scheme is based on the sensing redundancy of the system. The slip control

  19. Effect of impurities and strain amplitude on slip in fatigue of niobium single crystals

    Microsoft Academic Search

    Harmon D. Nine

    1975-01-01

    The type of slip deformation and the fatigue life in torsional fatigue of niobium single crystals were found to depend on both the cyclic strain amplitude and the interstitial impurity content. Two different slip-type populations were observed. At low strain amplitude, one population showed persistent slip bands, but the other, fatigued under identical conditions, showed asymmetric slip and asymmetric deformation.

  20. Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie & Diagonal Brace Joint Detail; Chord, Panel Post, Tie & Crossbracing Joint Detail - Dunlapsville Covered Bridge, Spanning East Fork Whitewater River, Dunlapsville, Union County, IN

  1. Frictional melting and stick-slip behavior in volcanic conduits

    NASA Astrophysics Data System (ADS)

    Kendrick, Jackie Evan; Lavallee, Yan; Hirose, Takehiro; di Toro, Giulio; Hornby, Adrian Jakob; Hess, Kai-Uwe; Dingwell, Donald Bruce

    2013-04-01

    Dome-building eruptions have catastrophic potential, with dome collapse leading to devastating pyroclastic flows with almost no precursory warning. During dome growth, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite and gouge. Under extreme friction, pseudotachylyte may form at the conduit margin. Understanding the conduit margin processes is vital to understanding the continuation of an eruption and we postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic "drumbeats", which are so commonly observed at dome-building volcanoes. This view is supported by field evidence in the form of pseudotachylytes identified in lava dome products at Soufrière Hills (Montserrat) and Mount St. Helens (USA). Both eruptions were characterised by repetitive, periodic seismicity and lava spine extrusion of highly viscous magma. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (<10 MPa). Starting from room temperature, frictional melting of the magmas occurs in under 1 s (<< 1 m) at 1.5 m/s (a speed that is achievable during stick-slip motion). At lower velocities melting occurs comparatively later due to dissipation of heat from the slip zone (e.g. 8-15 m at 0.1 m/s). Hence, given the ease with which melting is achieved in volcanic rocks, and considering the high ambient temperatures in volcanic conduits, frictional melting may thus be an inevitable consequence of viscous magma ascent. The shear resistance of the slip zone during the experiment is also monitored. Frictional melting induces a higher resistance to sliding than rock on rock, and viscous processes control the slip zone properties. Variable-rate HVR experiments which mimic rapid velocity fluctuations in stick-slip behavior demonstrate velocity-weakening behavior of melt, with a tendency for unstable slip. During ascent, magma may slip and undergo melting along the conduit margin. In the process the shear resistance of the slip zone is increased, acting as a viscous brake halting slip (the "stick" of stick-slip motion). Sufficient buoyancy-driven pressures from ascending magma below eventually overcome resistance to produce a rapid slip event (the "slip") along the melt-bearing slip zone, which is temporarily lubricated due to velocity-weakening. New magma below experiences the same slip event more slowly (as the magma decompresses) to produce a viscous brake and the process is repeated. This allows a fixed spatial locus that explains the repetitive drumbeat seismicity and the occurrence of "families" of similar seismic events. We conclude that stick-slip motion in volcanic conduits is a self-driving, frictional-melt-regulated force common to many dome building volcanoes.

  2. 4. From west side of boat slip; ore piles, unloaders, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. From west side of boat slip; ore piles, unloaders, blast furnaces, tube conveyors, ore conveyors, stock house, powerhouse. Looking north/northeast - Rouge Steel Company, 3001 Miller Road, Dearborn, Wayne County, MI

  3. GENERAL ELECTRIC SYNCHRONOUS MOTOR, SLIP RING END. NOTE THAT OUTSIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL ELECTRIC SYNCHRONOUS MOTOR, SLIP RING END. NOTE THAT OUTSIDE FRAME IS ROTATING ARMATURE, AND STATOR IS IN CENTER. ARCH SUPPORTS BRAKE BAND. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  4. Slip ring experience in long duration space applications

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1986-01-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use of multiple brushes and sufficient copper within the assembly, power transfer efficiency better than 99.95 percent for high voltage circuits can be achieved. A low slip ring failure rate based on actual space operation totalling billions of ring revolutions has been established. Well qualified suppliers who have been making slip rings for space use for over 25 years are available. It is hoped that the suspected problem in SEASAT will not be allowed to prejudice space system designer against these very useful mechanisms.

  5. Slip ring experience in long duration space applications

    NASA Astrophysics Data System (ADS)

    Phinney, Damon D.

    1986-05-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use of multiple brushes and sufficient copper within the assembly, power transfer efficiency better than 99.95 percent for high voltage circuits can be achieved. A low slip ring failure rate based on actual space operation totalling billions of ring revolutions has been established. Well qualified suppliers who have been making slip rings for space use for over 25 years are available. It is hoped that the suspected problem in SEASAT will not be allowed to prejudice space system designer against these very useful mechanisms.

  6. Slip, Trip and Fall Prevention for Healthcare Workers

    MedlinePLUS

    ... date. 34 | Slip, Trip, and Fall Prevention Employee Communication: Training and Involvement All healthcare facility employees are ... Umbrella bags? Barrier and access restriction devices? Employee Communication (Training and Employee Involvement)Yes No Locations / CommentsWho ...

  7. Temporomandibular Joint Dysfunction

    MedlinePLUS

    The temporomandibular joint (TMJ) connects your jaw to the side of your head. When it works well, it enables you to ... For people with TMJ dysfunction, problems with the joint and muscles around it may cause Pain that ...

  8. Analysis of slipped sequences in EST projects.

    PubMed

    Baudet, Christian; Dias, Zanoni

    2006-01-01

    Slippage is an important sequencing problem that can occur in EST projects. However, very few studies have addressed this. We propose three new methods to detect slippage artifacts: arithmetic mean method, geometric mean method, and echo coverage method. Each method is simple and has two different strategies for processing sequences: suffix and subsequence. Using the 291,689 EST sequences produced in the SUCEST project, we performed comparative tests between our proposed methods and the SUCEST method. The subsequence strategy is better than the suffix strategy, because it is not anchored at the end of the sequence, so it is more flexible to find slippage at the beginning of the EST. In a comparison with the SUCEST method, the advantage of our methods is that they do not discard the majority of the sequences marked as slippage, but instead only remove the slipped artifact from the sequence. Based on our tests the echo coverage method with subsequence strategy shows the best compromise between slippage detection and ease of calibration. PMID:16755508

  9. Quantum phase slips in Josephson junction rings

    NASA Astrophysics Data System (ADS)

    Rastelli, G.; Pop, I. M.; Hekking, F. W. J.

    2013-05-01

    We study quantum phase-slip (QPS) processes in a superconducting ring containing N Josephson junctions and threaded by an external static magnetic flux ?B. In such a system, a QPS consists of a quantum tunneling event connecting two distinct classical states of the phases with different persistent currents [Matveev , Phys. Rev. Lett.10.1103/PhysRevLett.89.096802 89, 096802 (2002)]. When the Josephson coupling energy EJ of the junctions is larger than the charging energy EC=e2/2C, where C is the junction capacitance, the quantum amplitude for the QPS process is exponentially small in the ratio EJ/EC. At given magnetic flux, each QPS can be described as the tunneling of the phase difference of a single junction of almost 2?, accompanied by a small harmonic displacement of the phase difference of the other N-1 junctions. As a consequence, the total QPS amplitude ?ring is a global property of the ring. Here, we study the dependence of ?ring on the ring size N, taking into account the effect of a finite capacitance C0 to ground, which leads to the appearance of low-frequency dispersive modes. Josephson and charging effects compete and lead to a nonmonotonic dependence of the ring's critical current on N. For N??, the system converges either towards a superconducting or an insulating state, depending on the ratio between the charging energy E0=e2/2C0 and the Josephson coupling energy EJ.

  10. Effects of slip testing parameters on measured coefficient of friction

    Microsoft Academic Search

    Kurt E. Beschorner; Mark S. Redfern; William L. Porter; Richard E. Debski

    2007-01-01

    Slips and falls are a major cause of injuries in the workplace. Devices that measure coefficient of friction (COF) of the shoe–floor–contaminant interface are used to evaluate slip resistance in various environments. Testing conditions (e.g. loading rate, timing, normal force, speed, shoe angle) are believed to affect COF measurements; however, the nature of that relationship is not well understood. This

  11. Measurement methods for slip-displacement signal registration

    NASA Astrophysics Data System (ADS)

    Kondratenko, Yuri P.

    1993-09-01

    The present paper deals with the robotic sensing problem by means of slip sensors. The analysis of the slip displacement signals detection methods developed at the Nickolayev Shipbuilding Institute is given, some of the sensors schemes and design topics are discussed, comprehensive attention is also given to their improvements allowing to raise a speed of response, sensitivity and to extend functional capabilities of the sensors under consideration,

  12. Complexity of Slow Slip Behind the Rupture Front

    NASA Astrophysics Data System (ADS)

    Rubin, A. M.

    2011-12-01

    Several physical mechanisms have been proposed for generating episodic slow slip, including fault gouge dilatancy at low effective stress, a velocity-weakening/velocity-strengthening transition with increasing slip speed, a fault size that is ``just right'', and appropriate forms of heterogeneity. Each, with various degrees of tuning, appears capable of generating slip speeds, stress drops, recurrence intervals, and migration speeds that are reasonably consistent with observations. In order to distinguish between these mechanisms it will be necessary to throw more observations into the mix. As geodetic data typically lack the necessary temporal and spatial resolution, the most detailed images we have of slow slip to date are inferred from locations of the associated tectonic tremor. In addition to the well-documented along-strike migration speeds of 5-10 km/day, tremor locations have led to the recognition of ``rapid tremor reversals'', that propagate tens of kilometers back in the direction from whence the main front came at roughly 10 times the speed [Houston et al., Nat. Geo., 2011], and ``tremor streaks'' that propagate tens of kilometers in the slip direction, roughly ten times faster still [Shelly et al., G-cubed, 2007; Ghosh et al., G-cubed, 2010]. The details of the time, space, and amplitude distribution of tremor behind the slow slip front may provide useful constraints on models of slow slip. If fortunate, I will report on efforts to more fully characterize tremor activity behind the propagating slow front in Cascadia. If less fortunate, I will explore some of the implications of the proposed mechanisms listed above for the behavior of slip speed behind the rupture front, along the lines of Rubin [G-cubed, 2011].

  13. Temperature Dependence of Atomic-Scale Stick-Slip Friction

    NASA Astrophysics Data System (ADS)

    Jansen, Lars; Hölscher, Hendrik; Fuchs, Harald; Schirmeisen, André

    2010-06-01

    We report experiments of atomic stick-slip friction on graphite as an explicit function of surface temperature between 100 and 300 K under ultrahigh vacuum conditions. A statistical analysis of the individual stick-slip events as a function of the velocity reveals an agreement with the thermally activated Prandtl-Tomlinson model at all temperatures. Taking into account an explicit temperature-dependence of the attempt frequency all data points collapse onto one single master curve.

  14. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S.

    1997-03-01

    It is widely accepted that dead reckoning based on the rolling with no slip condition on wheels is not a reliable method to ascertain the position and orientation of a mobile robot for any reasonable distance. We establish that wheel slip is inevitable under the dynamic model of motion using classical results on the accessibility and controllability in nonlinear control theory and an analytical model of rolling of two linearly elastic bodies.

  15. Reactivated strike–slip faults: examples from north Cornwall, UK

    Microsoft Academic Search

    Young-Seog Kim; Jim R Andrews; David J Sanderson

    2001-01-01

    Several strike–slip faults at Crackington Haven, UK show evidence of right-lateral movement with tip cracks and dilatational jogs, which have been reactivated by left-lateral strike–slip movement. Evidence for reactivation includes two slickenside striae on a single fault surface, two groups of tip cracks with different orientations and very low displacement gradients or negative (left-lateral) displacements at fault tips.Evidence for the

  16. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S.

    1997-03-01

    It is widely accepted that dead reckoning based on the rolling with no slip condition on wheels is not a reliable method to ascertain the position and orientation of a mobile robot for any reasonable distance. The author establishes that wheel slip is inevitable under the dynamic model of motion using classical results on the accessibility and controllability in nonlinear control theory and an analytical model of rolling of two linearly elastic bodies.

  17. Refining the Magnitude of the Shallow Slip Deficit

    NASA Astrophysics Data System (ADS)

    Xu, X.; Tong, X.; Sandwell, D. T.; Milliner, C. W. D.

    2014-12-01

    Geodetic inversions for slip versus depth for several major (Mw > 7) strike-slip earthquakes (e.g. 1992 Landers, 1999 Hector Mine, 2010 El_Mayor-Cucapah) show a 10% to 40% reduction in slip near surface (depth < 2 km) compared to the slip at deeper depths (5 to 8 km). This has been called the shallow slip deficit (SSD). The large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes. One potential explanation for the SSD is that the previous geodetic inversions used incomplete data that do not go close to fault so the shallow portions of the slip models were poorly resolved and generally underestimated. In this study we improve the geodetic inversion, especially at shallow depth by: 1) refining the InSAR processing with non-boxcar phase filtering, model-dependent range corrections, more complete phase unwrapping by SNAPHU using a correlation mask and allowing a phase discontinuity along the rupture; 2) including near-fault offset data from optical imagery and SAR azimuth offsets; 3) using more detailed fault geometry; 4) and using additional campaign GPS data. With these improved observations, the slip inversion has significantly increased resolution at shallow depth. For the Landers rupture the SSD is reduced from 45% to 16%. Similarly for the Hector Mine rupture the SSD is reduced from 15% to 5%. We are assembling all the relevant co-seismic data for the El Major-Cucapah earthquake and will report the inversion result with its SSD at the meeting.

  18. Earliest Gait Deviations During Slips: Implications For Recovery

    Microsoft Academic Search

    Kurt E. Beschorner; Mark S. Redfern; Rakié Cham

    2012-01-01

    This study identified that deviations in vertical force and knee angle\\/angular velocity of the slipping leg occur earlier in stance and with greater magnitude than other lower-body motions when a person experiences an unexpected slip. Deviations in the ankle angle\\/angular velocity and hip angular velocity occurred soon after the knee angle and with smaller magnitudes. These results suggest that foot

  19. Strike-slip duplexing on Jupiter's icy moon Europa

    Microsoft Academic Search

    Louise M. Prockter; Robert T. Pappalardo; James W. Head

    2000-01-01

    Agenor Linea is a ~1500 km long, ~20-30 km wide geologically young zone of deformation on Jupiter's icy moon, Europa. On the basis of recent Galileo high-resolution images, we interpret Agenor Linea as a strike-slip zone formed in three stages by a combination of lithospheric separation, extension, and dextral horizontal shear. Agenor Linea exhibits excellent examples of strike-slip duplexes in

  20. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S. [Oak Ridge National Lab., TN (United States). Robotics and Process Systems Div.

    1996-06-01

    It is widely accepted that dead-reckoning based on the rolling with no-slip condition on the wheels is not a reliable method to ascertain the position and orientation of a mobile robot for any reasonable distance. The authors establish that wheel slip is inevitable under the dynamic model of motion using classical results on the accessibility and controllability in nonlinear control theory and an analytical model of rolling of two linearly elastic bodies.

  1. Sacroiliac joint pain - aftercare

    MedlinePLUS

    The sacroiliac joint (SIJ) is a term used to describe the place where the sacrum and the iliac bones join. The ... The main purpose of the joint is to connect the spine and the pelvis. As a result, there is very little movement at the sacroiliac joint. Listed ...

  2. Stick-slip statistics of a physical slider block model

    NASA Astrophysics Data System (ADS)

    Brueckl, Ewald; Lederbauer, Stefan; Mertl, Stefan; Roch, Karl-Heinz

    2010-05-01

    An exhibition concerning the various scientific, technical, and social aspects of earthquakes has been organized as an Austrian contribution to IYPE - International Year of Planet Earth. In order to support the understanding of the elastic rebound theory a physical slider block model has been constructed. This model consists of a granite base plate and a granite slider block, connected to a lever by a leaf spring. The lever is driven parallel to the base plate with a constant speed in the range of 1 - 10 mm/s. The lever can move about 1 m in one direction. Thereafter the polarity of displacement is changed automatically. Opto-electronic distance measuring modules measure the displacement of the constantly moving lever and the stick-slip movement of the slider block. A geophone mounted on the slider block receives the vibrations of the slider block during the slip. From theory a periodic slip has to be expected. However, because of slight spatial changes of friction between the base plate and the slider block, individual slip distances vary in the range of 2 - 20 mm. Besides the speed of the lever further parameters of the physical slider block model can be varied: normal force between base plate and slider block, grain size and thickness of quartz sand simulating fault gouge, and stiffness of the leave spring. The stick slip statistics and derived quantities (e.g., stress release) will be shown and the influence of the variable parameters on the stick slip behaviour analyzed.

  3. Analysis of pinnate joints in the Mount Desert Island granite: Implications for postintrusion kinematics in the coastal volcanic belt, Maine

    SciTech Connect

    Engelder, T. (Pennsylvania State Univ., University Park (USA))

    1989-06-01

    The mount desert Island granite is cut by fractures displaying one of four types of surface morphology: (1) smooth to undulatory; (2) stepped in the form of en echelon cracks; (3) striated with linear fibers; and (4) irregular with cataclastic grains. These surfaces belong to joints, host fractures with pinnate joints, reactivated joints or fractures, and deformation bands (shear fractures), respectively. Pinnate joints, like striations on slickensides, are structures indicative of the orientation of a the slip vector and sense of shear on host fractures. Although fractures in the Mount Desert Island granite cluster into two major sets (N20{degree}W and N45{degree}E), host fractures with pinnate joints and shear fractures favor the N45{degree}E orientation. A kinematic analysis of the pinnate joints indicates a predominantly dextral strike-slip sense of movement on northeast-trending fractures. This result agrees with previous work suggesting that a prominent postintrusion tectonic event in southeast Maine consisted of dextral strike-slip motion on northeast-trending faults.

  4. Experimental investigation of frictional melting of argillite at high slip rates: Implications for seismic slip in subduction-accretion complexes

    E-print Network

    Fialko, Yuri

    to investigate conditions in seismogenic zones. Pseudotachy- lytes (i.e., solidified frictional melts) were- plexes are direct evidence that at least some seismic slip along subduction thrusts and out

  5. Gait parameters as predictors of slip severity in younger and older adults

    Microsoft Academic Search

    B. E. Moyer; A. J. Chambers; M. S. Redfern; R. Cham

    2006-01-01

    This study investigated the association between slip severity and pre-slip gait characteristics of younger and older subjects. Sixteen younger and eleven older healthy adults walked onto an unexpectedly slippery surface. Slip severity was categorized as either hazardous or non-hazardous using a 1.0 ms peak slip velocity threshold. The results showed that hazardous slips were associated with greater step lengths (normalized by

  6. Effects of perturbation-based slip training using a virtual reality environment on slip-induced falls.

    PubMed

    Parijat, Prakriti; Lockhart, Thurmon E; Liu, Jian

    2015-04-01

    The purpose of the current study was to design and evaluate the effectiveness of virtual reality training in improving recovery reactions and reducing fall frequency in older adults. Twenty-four older adults were recruited and randomly assigned to two groups (virtual reality training and control). Both groups underwent three sessions including baseline slip, training and transfer of training on slippery surface. Both groups experienced two slips, one during baseline and the other during the transfer of training trial. The training group underwent 12 simulated slips using a visual perturbation induced by tilting a virtual reality scene while walking on the treadmill and the control group performed normal walking during the training session. Kinematic and kinetic data were collected during all the sessions. Results demonstrated a reduced incidence of falls in the training group during the transfer of training trial as compared to the control group. The training group was able to transfer reactive control strategies learned during training to the second slip trial. The reactive adjustments included reduced slip distance. Additionally, gait parameters reflective of gait instability (stride length, step width, variability in stride velocity) reduced after walking in the VR environment for 15-20 min. The results indicated a beneficial effect of the virtual reality training in reducing slip severity and recovery kinematics in healthy older adults. PMID:25245221

  7. Late Pleistocene, Holocene, and decadal constancy of slip-rate of the Doruneh strike-slip fault, Iran.

    NASA Astrophysics Data System (ADS)

    Walker, R. T.; Fattahi, M.; Mousavi, Z.; Pathier, E.; Sloan, R. A.; Talebian, M.; Thomas, A. L.; Walpersdorf, A.

    2014-12-01

    The Doruneh left-lateral strike-slip fault of NE Iran has a prominent expression in the landscape, showing that the fault is active in the late Quaternary. Existing estimates of its slip-rate vary, however, which has led to suggestions that it may exhibit temporal changes in activity. Using high-resolution optical satellite imagery we make reconstructions of displacement across four alluvial fans that cross the Doruneh fault, and determine the ages of these fans using luminescence dating, combined with U-series dating of pedogenic carbonates in one case. The four fans, which vary in age from 10-100 kyr, yield estimates of slip rate of ~2-3 mm/yr. We compare the average slip-rate measurements to the rate of accumulation of strain across the Doruneh fault using GPS and InSAR measurements, and find that the slip-rate is likely to have remained constant - within the uncertainty of our measurements - over the last ~100 ka. The slip-rate that we measure is consistent with the E-W left-lateral Doruneh fault accommodating N-S right-lateral faulting by 'bookshelf' faulting, with clockwise rotation about a vertical axis, in a similar manner to the Eastern California Shear Zone.

  8. Effects of Tidal Modulation in Heterogeneous Models of Slow Slip

    NASA Astrophysics Data System (ADS)

    Skarbek, R. M.; Rempel, A. W.; Thomas, A.

    2014-12-01

    Since their discovery, numerous models have been put forward to explain the occurance of slow slip and associated tremor. These models invoke a wide array of causal mechanisms and are all successful in reproducing the first-order behavior of slow-slip events. Discriminating amongst the various proposed models requires looking at second-order effects of slow slip and tremor. Here, we consider the effects of tidal modulation on slow slip in subduction zones. A great deal of observational evidence has established that slow-slip and associated tremor are modulated by the small stress perturbations associated with tides and teleseismic events. Recent modeling studies that have examined the influence of tidal stresses (<10 kPa) have focused either on the effects of tidally induced changes in shear stress, or on changes in shear and normal stress that coincide. However, along the Cascadia margin, the relative phase of the tidally induced fault-normal and shear stresses depends on position along the plate boundary fault, and can vary from being in phase, to completely out of phase. We report on the predictions of models designed to examine the sensitivity of slow-slip in subduction zones to the phase shift ? between tidally induced normal and shear stress perturbations. We consider both simple spring-slider and 1-D elastodynamic models that are designed to mimic the effects of geologic heterogeneity by allowing for variations in the rate-and-state frictional parameters. For a given slow-slip event, spring-slider results indicate that the phase lag ?v between the peak slip rate and the tidally induced shear stress perturbation depends on both the phase shift ?, and the perturbation amplitude. Models parameterized for Cascadia are capable of producing phase lags ?v within the range (15? to 30?) of those reported by Royer et al. (JGR, 2014). Additionally, our models predict that the correlation between tidally induced shear stress perturbations and resultant slip also depends on the phase shift ?. Our results indicate that the influence of tides, especially the effects of phase differences between tidaly induced shear and normal stresses, must be taken into account when evaluating the physical mechanisms of slow-slip and tremor.

  9. Strike-slip sedimentation: Dead Sea basin

    SciTech Connect

    Manspeizer, W.

    1986-05-01

    The Dead Sea rift extends for 1000 km along a transform plate boundary that has had left-lateral displacement of 150 km since the Miocene. The rift consists of a series of en-echelon, left-stepping (looking north), north-striking, strike-slip faults that are joined by a series of grabens (e.g., the Dead Sea basin). This basin developed as an asymmetric rhomb-shaped graben with nearly vertical, north-striking normal border faults (east and west margins), north-northeast-dipping listric normal faults (south margin), and a south-facing inclined basement (north margin). Displacement along the transform produced three basins, whose depocenters migrated north where they received Miocene fluvial clastics, Pliocene marine evaporites, and Pleistocene-Holocene lacustrine sediments. Graben filling today is governed largely by tectonism, which modifies rift climates and morphology. As warm moist air from the Mediterranean Sea rises over the rift shoulders, it cools adiabatically, yielding up to 900 mm of rain water for high discharge, ephemeral streams that prograde vast prisms of coalescing shallow water fan deltas along the western border fault. The eastern basin margin, by contrast, is dominated by an active transform boundary, a narrow shelf, and a spectacular deep (750 m below MSL) that receives deep water clastics. Whereas the northern margin of the basin receives fine-grained clastics from the prograding delta of the Jordan River (a perennial stream, whose drainage basin lies in a humid terrane far to the north), the southern margin is dominated by evaporites that are precipitated in shallow water basins (upon adiabatic warming of descending air).

  10. Regional Slip Tendency Analysis of the Great Basin Region

    SciTech Connect

    Faulds, James E.

    2013-09-30

    Slip and dilation tendency on the Great Basin fault surfaces (from the USGS Quaternary Fault Database) were calculated using 3DStress (software produced by Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by the measured ambient stress field. - Values range from a maximum of 1 (a fault plane ideally oriented to slip or dilate under ambient stress conditions) to zero (a fault plane with no potential to slip or dilate). - Slip and dilation tendency values were calculated for each fault in the Great Basin. As dip is unknown for many faults in the USGS Quaternary Fault Database, we made these calculations using the dip for each fault that would yield the maximum slip or dilation tendency. As such, these results should be viewed as maximum slip and dilation tendency. - The resulting along?fault and fault?to?fault variation in slip or dilation potential is a proxy for along fault and fault?to?fault variation in fluid flow conduit potential. Stress Magnitudes and directions were calculated across the entire Great Basin. Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson?Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005). The minimum horizontal stress direction (Shmin) was contoured, and spatial bins with common Shmin directions were calculated. Based on this technique, we subdivided the Great Basin into nine regions (Shmin <070, 070140). Slip and dilation tendency were calculated using 3DStress for the faults within each region using the mean Shmin for the region. Shmin variation throughout Great Basin are shown on Figure 3. For faults within the Great Basin proper, we applied a normal faulting stress regime, where the vertical stress (sv) is larger than the maximum horizontal stress (shmax), which is larger than the minimum horizontal stress (sv>shmax>shmin). Based on visual inspection of the limited stress magnitude data in the Great Basin, we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46. These values are consistent with stress magnitude data at both Dixie Valley (Hickman et al., 2000) and Yucca Mountain (Stock et al., 1985). For faults within the Walker Lane/Eastern California Shear Zone, we applied a strike?slip faulting stress, where shmax > sv > shmin. Upon visual inspection of limited stress magnitude data from the Walker Lane and Eastern California Shear zone, we chose values such that SHmin/SHmax = .46 and Shmin/Sv= .527 representative of the region. Results: The results of our slip and dilation tendency analysis are shown in Figures 4 (dilation tendency), 5 (slip tendency) and 6 (slip tendency + dilation tendency). Shmin varies from northwest to east?west trending throughout much of the Great Basin. As such, north? to northeast?striking faults have the highest tendency to slip and to dilate, depending on the local trend of shmin. These results provide a first order filter on faults and fault systems in the Great Basin, affording focusing of local?scale exploration efforts for blind or hidden geothermal resources.

  11. Nucleation and triggering of earthquake slip: effect of periodic stresses

    USGS Publications Warehouse

    Dieterich, J.H.

    1987-01-01

    Results of stability analyses for spring and slider systems, with state variable constitutive properties, are applied to slip on embedded fault patches. Unstable slip may nucleate only if the slipping patch exceeds some minimum size. Subsequent to the onset of instability the earthquake slip may propagate well beyond the patch. It is proposed that the seismicity of a volume of the earth's crust is determined by the distribution of initial conditions on the population of fault patches that nucleate earthquake slip, and the loading history acting upon the volume. Patches with constitutive properties inferred from laboratory experiments are characterized by an interval of self-driven accelerating slip prior to instability, if initial stress exceeds a minimum threshold. This delayed instability of the patches provides an explanation for the occurrence of aftershocks and foreshocks including decay of earthquake rates by time-1. A population of patches subjected to loading with a periodic component results in periodic variation of the rate of occurrence of instabilities. The change of the rate of seismicity for a sinusoidal load is proportional to the amplitude of the periodic stress component and inversely proportional to both the normal stress acting on the fault patches and the constitutive parameter, A1, that controls the direct velocity dependence of fault slip. Values of A1 representative of laboratory experiments indicate that in a homogeneous crust, correlation of earthquake rates with earth tides should not be detectable at normal stresses in excess of about 8 MPa. Correlation of earthquakes with tides at higher normal stresses can be explained if there exist inhomogeneities that locally amplify the magnitude of the tidal stresses. Such amplification might occur near magma chambers or other soft inclusions in the crust and possibly near the ends of creeping fault segments if the creep or afterslip rates vary in response to tides. Observations of seismicity rate variations associated with seasonal fluctuations of reservoir levels appear to be consistent with the model. ?? 1987.

  12. Dynamics of Slip Fronts at Frictional Interfaces: Analysis of Slip Precursors

    NASA Astrophysics Data System (ADS)

    Radiguet, M.; Kammer, D. S.; Molinari, J.

    2012-12-01

    The transition from sticking to sliding of frictional interfaces is a phenomenon of importance for many physical systems in nature as well as in engineering. This transition is marked by the occurrence of local slip events, often called precursors, which appear before the global sliding is observed. Such precursors to global sliding may occur on segments of geophysical faults subject to non uniform shear loading, for example a fault segment located between a locked and steadily slipping region. Sequences of small earthquakes (foreshocks) of identical seismic characteristics have been observed preceding large earthquakes in several regions. The links between the occurrence of these foreshocks and the nucleation process of large earthquakes remains elusive, but has large implications for earthquake prediction and risk assessment. These precursors have been studied experimentally by Rubinstein et al. [2007]. However, the experimental study of interfaces is challenging due to difficulties to access information at the interface. Therefore, numerical simulations are needed in order to give additional information for accurate analysis. First attempts have been undertaken using simple spring-block systems [Maegawa et al. 2010, Tromborg et al. 2011]. In this study however, we use the finite-element method, which allows us to represent accurately the continuum character of the system, and to investigate the onset and evolution of sliding at a frictional interface. The studied setup is similar to the experimental setup used by Ben-David et al. [2010]. It consists of a block of viscoelastic material in contact with a rigid body. A velocity-weakening friction law controls the friction at the interface. Special care is taken to apply appropriate regularization and viscosity in the simulation. We apply a shear load to the block, either on the top surface of the block or on one side. In both cases, the resulting shear tractions at the interface are non-uniform. The stress distribution presents a high concentration close to the edge when the load is applied on the side. Applying a non-uniform shear loading, we observe a sequence of slip precursors, which initiate at shear levels well below the global static friction threshold. These precursors stop before propagating over the entire interface, and their length increase with increasing shear force. Our results are consistent with previous experimental observations [Rubinstein et al., 2007]. We analyze the relation between the applied load, the precursors length, and the evolution of stresses at the interface.

  13. Interaction between slip events, erosion and sedimentation along an active strike-slip fault: Insights from analog models

    NASA Astrophysics Data System (ADS)

    Chatton, M.; Malavieille, J.; Dominguez, S.; Manighetti, I.; Romano, C.; Beauprêtre, S.; Garembois, S.; Larroque, C.

    2012-04-01

    Recovering information on past (i.e., last 102-104 yrs) large earthquakes on faults is a challenge. The classical approach -especially used on strike-slip faults- consists in searching morphological markers such as river channels, streams, alluvial fans, ridges or terrace risers, etc, that would be offset by the fault, and measure these offsets by reconstructing the original position and shape of the markers. Combined with the dating of the offset markers, this morphotectonic paleoseismological approach may provide information on the slips and ages of the most recent earthquakes on the fault under study. Yet, the approach is complex as it depends on the recognition of unambiguous paired markers on either side of the fault. And our capability to recognize similar markers on either side of a fault in turn greatly depends on the 'evolution' that these markers may have sustained subsequently to their very first slip disruption. Did the repeating earthquake slip events modify their surface appearance? Did their morphology and position (ex: burying, destruction, modification, etc) evolve with the sedimentation and erosion that might have occurred during the fault history? Etc. These questions have rarely been approached for they are difficult to address in natural settings. And as we are unable to answer them in the natural cases that we study, the slip reconstructions that we provide are generally uncertain as they are likely based on an incomplete or biased record of the past fault slips. Therefore, the objective of our work is to contribute to better understand and document the nature and 'evolution' of the morphological markers that are commonly used in morphotectonic and paleoseismological analyses, especially along strike-slip faults. We approach these questions experimentally. We have developed an original experimental set-up made to simulate repeated slip events on a strike-slip fault placed in a wet environment sustaining sedimentation and erosion. The fault device is indeed coupled with a rainfall system, while an optical measurement apparatus that includes digital cameras and a laser interferometer, allows observing and measuring continuously at very high resolution the evolution of the model surface morphology. The analog material is a mix of granular materials -glass microbeads, silica powder and plastic powder saturated in water, whose mass composition and, consequently, mechanical properties lead to a geometric scaling of about 1:10 000 and to a temporal scaling on the order of one second equivalent to a few dozens of years. The protocol allows monitoring together the evolution of the fault and that of the morphological markers that the fault progressively offsets as slip events are imposed. We have conducted several experiences in different settings and we will present the preliminary results that we have obtained. We basically could survey the formation and evolution of a strike-slip fault from its immature stages up to one hundred repeated slip events. Under the combined effects of accumulating slip, erosion and sedimentation, the model surface exhibits tectonic and morphological structures similar to natural features (Riedel's shears, pressure and shutter ridges, pull-apart basins, alluvial fans, terrace risers, braided rivers, etc), whose space and time evolution can be precisely analyzed. Deformation partitioning, sequential formation of alluvial terraces, stream captures, development of 'traps' filling with sediments, etc, are especially observed. The control on the imposed amplitude and frequency of the rainfall cycles allows us to examine the impact of these rainfalls on the fault morphology and the evolution of the associated morphological markers. Finally, we can compare the imposed slip events (number, amplitudes, repeat times) with the cumulative offsets eventually visible and measurable at the model surface. Marked discrepancies are found between imposed and final apparent offsets that shed light on the uncertainties that may affect the morphological and paleoseismological analyses performed on nat

  14. Slip stream apparatus and method for treating water in a circulating water system

    DOEpatents

    Cleveland, J.R.

    1997-03-18

    An apparatus is described for treating water in a circulating water system that has a cooling water basin which includes a slip stream conduit in flow communication with the circulating water system, a source of acid solution in flow communication with the slip stream conduit, and a decarbonator in flow communication with the slip stream conduit and the cooling water basin. In use, a slip stream of circulating water is drawn from the circulating water system into the slip stream conduit of the apparatus. The slip stream pH is lowered by contact with an acid solution provided from the source thereof. The slip stream is then passed through a decarbonator to form a treated slip stream, and the treated slip stream is returned to the cooling water basin. 4 figs.

  15. Slip stream apparatus and method for treating water in a circulating water system

    DOEpatents

    Cleveland, Joe R. (West Hills, CA)

    1997-01-01

    An apparatus (10) for treating water in a circulating water system (12) t has a cooling water basin (14) includes a slip stream conduit (16) in flow communication with the circulating water system (12), a source (36) of acid solution in flow communication with the slip stream conduit (16), and a decarbonator (58) in flow communication with the slip stream conduit (16) and the cooling water basin (14). In use, a slip stream of circulating water is drawn from the circulating water system (12) into the slip stream conduit (16) of the apparatus (10). The slip stream pH is lowered by contact with an acid solution provided from the source (36) thereof. The slip stream is then passed through a decarbonator (58) to form a treated slip stream, and the treated slip stream is returned to the cooling water basin (14).

  16. Energy Partitioning during Frictional Sliding at Coseismic Slip Rates

    NASA Astrophysics Data System (ADS)

    Hirose, T.; Mizoguchi, K.

    2008-12-01

    Determination of the energy partitioning during an earthquake is key to understanding the physics of earthquakes (e.g., Kanamori and Rivera, 2006). Observations made on natural faults that have experienced earthquakes suggest that part of the energy dissipates into a volume of rock surrounding the fault though grain crushing processes, forming fault gouge (e.g., Wilson et al., 2005). Thus we performed high-velocity wear experiments using a rotary-shear apparatus, in order to estimate the partitioning of the frictional work into heat and surface energy during frictional sliding at nearly coseismic slip rates. In particular, we attempted to test whether the ratio of the energy partitioning varies as a function of slip rate. The ratio of dissipated energy as heat to the total frictional work was estimated from the difference between measured temperature around the sliding surfaces and calculated temperature by 2D-FEM on the assumption that all frictional work converts into heat. The surface energy was estimated based on the particle size distribution of the wear materials, which was determined by FE-SEM image analysis. The particles size ranged between 0.03 and 10 ?m in average diameter. In the experiments, hollow cylindrical specimens of gabbro were slid at slip rates of 0.004 to 0.3 m/s and normal stresses of 0.2 to 5.6 MPa under unconfined and dry conditions. Rock powder (gouge) was continuously produced by abrasive wear of initially bare fault surfaces during sliding. Because the sliding surfaces were not confined in the experiments, the gouge was extruded from the fault surfaces, resulting in shortening of axial length of specimen. In this study, we defined the dimensionless wear rate, given by that an axial shortening rate of the specimen was divided by slip rate. Then, we examined how the wear rate and temperature changed as a function of the rate of frictional work per a unit fault area, Ef, determined by shear stress multiplied by slip rate. Hereafter, Q and Us denote the rate of heat and surface energy per a unit fault area, respectively. Our experimental results can be summarized as follows. (1) The wear rate increased almost linearly with increasing Ef. The slope of the wear rate versus Ef was higher at lower slip rates, but it became constant at slip rate of >0.11m/s. This means that more gouge forms at lower slip rate for a given Ef. (2) The grain size distribution of the gouge developed at different experimental conditions was nearly identical; the calculated specific surface area from the size distribution was nearly constant (1.3 to 1.6 m2/g). Therefore the Us is proportional only to the wear rate. This indicates that the trend of the wear rate versus Ef curves corresponds to that of the Us versus Ef curves. (3) The results of (1) and (2) suggest that the ratio of the surface energy to the fictional work (Us/Ef) increases with increasing Ef and decreasing slip rate. The Us/Ef at Ef of 43 kJ/m2s was 0.012% and 0.009% at slip rates of 0.025 m/s and 0.11 m/s, respectively. (4) In contrast, the ratio of the energy dissipated as heat to the frictional work (Q/Ef) is independent of slip rate, and however it decreases with increasing Ef. The Q/Ef decreased from ~95% at Ef of 20 kJ/m2s to ~70% at Ef of 210 kJ/m2s. Our experiments at nearly coseismic slip conditions suggest that slip rate and Ef are important parameters to determine the energy partitioning of the frictional work during an earthquake.

  17. Effective slip in pressure-driven flow past super-hydrophobic stripes

    NASA Astrophysics Data System (ADS)

    Belyaev, A. V.; Vinogradova, O. I.

    2010-05-01

    Super-hydrophobic array of grooves containing trapped gas (stripes), have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused on idealized cases of stick-perfect slip stripes, with limited guidance. Here, we analyze the experimentally relevant situation of a pressure-driven flow past striped slip-stick surfaces with arbitrary local slip at the gas sectors. We derive analytical formulas for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that can be used for any surface slip fraction (validated by numerical calculations). By representing eigenvalues of the slip length-tensor, they allow us to obtain the effective slip for any orientation of stripes with respect to the mean flow. Our results imply that flow past stripes is controlled by the ratio of the local slip length to texture size. In case of a large (compared to the texture period) slip at the gas areas, surface anisotropy leads to a tensorial effective slip, by attaining the values predicted earlier for a perfect local slip. Both effective slip lengths and anisotropy of the flow decrease when local slip becomes of the order of texture period. In the case of small slip, we predict simple surface-averaged, isotropic flows (independent of orientation). These results provide a framework for the rational design of super-hydrophobic surfaces and devices.

  18. Scaling of the Critical Slip Distance in Granular Layers

    NASA Astrophysics Data System (ADS)

    Hatano, T.

    2009-12-01

    A natural fault has the cataclasite core zone, along which shear deformation concentrates. Rheology of these granular matters thus provides us an important insight in considering the nature of friction on faults from a microscopic point of view. Unfortunately, to this date, our understanding of the rheological properties of granular matter is still poor except for dilute flow to which the kinetic theory of gases can apply. Thus, a computational approach has played a considerable role in investigating dense granular rheology to propose some constitutive laws for steady shear flow [1]. However, a transient state is still a frontier in the sense that we do not have any constitutive laws. The description of transient states is particularly important in the context of seismology because an earthquake is essentially a nonstationary process. An important quantity is the critical slip distance, over which a fault looses its frictional strength with the coseismic slip, because it determines the maximum acceleration of the seismic ground motion as well as the rupture nucleation process. However, regardless of its importance, we still cannot explain the critical slip distance ranging from 0.1 to 1 m, which is obtained by the seismic inversion. It is rather paradoxical that the critical slip distance obtained in a typical experiment is of the order of micrometers. Understanding the physics that determines the critical slip distance to explain the wide gap between a natural fault and a laboratory is thus a central problem in seismology. Here we show a novel constitutive law that describes a transient process in granular layers using discrete element simulation [2]. In particular, analyzing a transient process in which the sliding velocity is instantaneously changed, we find that the critical slip distance is proportional to the sliding velocity. We thus define the relaxation time, which is independent of the sliding velocity. It is found that the relaxation time is proportional to the layer thickness and inversely proportional to the square root of the pressure. An evolution law for the relaxation process is proposed, which does not contain any length constants describing the surface geometry but the relaxation time of the bulk granular matter. As a result, the critical slip distance is scaled with a typical length scale of a system. It is proportional to the layer thickness in an instantaneous velocity change experiment, whereas it is scaled with the total slip distance in a spring-block system on granular layers. References [1] Hatano, T., Power-law friction in closely-packed granular materials, Phys. Rev. E 75, 060301(R) (2007) [2] Hatano, T., Scaling of the critical slip distance in granular layers, to appear in Geophys. Res. Lett. (2009)

  19. Slip Running Reconnection in Magnetic Flux Ropes

    NASA Astrophysics Data System (ADS)

    Gekelman, W. N.; Van Compernolle, B.; Vincena, S. T.; De Hass, T.

    2012-12-01

    Magnetic flux ropes are due to helical currents and form a dense carpet of arches on the surface of the sun. Occasionally one tears loose as a coronal mass ejection and its rope structure can be detected by satellites close to the earth. Current sheets can tear into filaments and these are nothing other than flux ropes. Ropes are not static, they exert mutual ?c{J}×?c{B} forces causing them to twist about each other and eventually merge. Kink instabilities cause them to violently smash into each other and reconnect at the point of contact. We report on experiments on two adjacent ropes done in the large plasma device (LAPD) at UCLA ( ne ˜ 1012, Te ˜ 6 eV, B0z=330G, Brope}\\cong{10G,trep=1 Hz). The currents and magnetic fields form exotic shapes with no ignorable direction and no magnetic nulls. Volumetric space-time data (70,600 spatial locations) show multiple reconnection sites with time-dependent locations. The concept of a quasi-separatrix layer (QSL), a tool to understand and visualize 3D magnetic field lines reconnection without null points is introduced. Three-dimensional measurements of the QSL derived from magnetic field data are presented. Within the QSL field lines that start close to one another rapidly diverge as they pass through one or more reconnection regions. The motion of magnetic field lines are traced as reconnection proceeds and they are observed to slip through the regions of space where the QSL is largest. As the interaction proceeds we double the current in the ropes. This accompanied by intense heating as observed in uv light and plasma flows measured by Mach probes. The interaction of the ropes is clearly seen by vislaulizng magnetic field data , as well as in images from a fast framing camera. Work supported by the Dept. of Energy and The National Science Foundation, done at the Basic Plasma Science Facility at UCLA.Magnetic Field lines (measured) of three flux ropes and the plasma currents associated with them

  20. Research on slip resistance measurements--a new challenge.

    PubMed

    Kim, In-Ju; Nagata, Hisao

    2008-01-01

    Slips, trips and falls are one of the most common causes of injuries and fatalities in the general community and industry. The control of such incidents involves a complex array of factors including the characteristics of each individual's footwear and gait dynamics, walking and working surfaces, and environmental conditions. Notwithstanding this complexity, slip resistance properties have been widely measured as a form of coefficient of friction (COF) index at the sliding interface between the shoes and floors. Since the COF measurements were commonly adopted to evaluate slip potentials, it has been found that there were controversies in the interpretation of COF measurement results. This study, therefore, was principally focused on broadening the knowledge base and developing new ideas on which improvements in the validity and reliability of slip resistance measurements might be made. To achieve this goal, crucial problems on the current concept of slip resistance measurement were extensively analysed by a tribological point of view where principle understanding of the shoe-floor friction and wear phenomena could be made. Based on this approach, new theoretical models were suggested. PMID:18270452

  1. Measurement of Quantum Phase-Slips in Josephson Junction Chains

    NASA Astrophysics Data System (ADS)

    Guichard, Wiebke

    2011-03-01

    Quantum phase-slip dynamics in Josephson junction chains could provide the basis for the realization of a new type of topologically protected qubit or for the implementation of a new current standard. I will present measurements of the effect of quantum phase-slips on the ground state of a Josephson junction chain. We can tune in situ the strength of the phase-slips. These phase-slips are the result of fluctuations induced by the finite charging energy of each junction in the chain. Our measurements demonstrate that a Josephson junction chain under phase bias constraint behaves in a collective way. I will also show evidence of coherent phase-slip interference, the so called Aharonov-Casher effect. This phenomenon is the dual of the well known Aharonov-Bohm interference. In collaboration with I.M. Pop, Institut Neel, C.N.R.S. and Universite Joseph Fourier, BP 166, 38042 Grenoble, France; I. Protopopov, L. D. Landau Institute for Theoretical Physics, Kosygin str. 2, Moscow 119334, Russia and Institut fuer Nanotechnologie, Karlsruher Institut fuer Technologie, 76021 Karlsruhe, Germany; and F. Lecocq, Z. Peng, B. Pannetier, O. Buisson, Institut Neel, C.N.R.S. and Universite Joseph Fourier. European STREP MIDAS, ANR QUANTJO.

  2. Scaling analysis for the investigation of slip mechanisms in nanofluids.

    PubMed

    Savithiri, S; Pattamatta, Arvind; Das, Sarit K

    2011-01-01

    The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it. PMID:21791036

  3. Flow reversals in turbulent convection with free-slip walls

    NASA Astrophysics Data System (ADS)

    Verma, Mahendra K.; Ambhire, Siddhesh C.; Pandey, Ambrish

    2015-04-01

    We perform numerical simulations of turbulent convection for infinite Prandtl number with free-slip walls and study the dynamics of flow reversals. We show interesting correlations between the flow reversals and the nonlinear interactions among the large-scale flow structures represented by the modes (1, 1), (2, 1), (3, 1), and some others. After a flow reversal, the odd modes, e.g., (1, 1) and (3, 1), switch sign, but the even modes, e.g., (2, 2), retain their sign. The mixed modes (1, 2) and (2, 1) fluctuate around zero. Using the properties of the modes and their interactions, we show that they form a Klein four-group Z2 × Z2. We also show that for the free-slip boundary condition, the corner rolls and vortex reconnection are absent during a flow reversal, in contrast to active role played by them in flow reversals for the no-slip boundary condition. We argue that the flow reversals with the no-slip and free-slip boundary conditions are different because they are induced by nonlinearities (u ? ?)u and (u ? ?) ?, respectively.

  4. Path Following with Slip Compensation for a Mars Rover

    NASA Technical Reports Server (NTRS)

    Helmick, Daniel; Cheng, Yang; Clouse, Daniel; Matthies, Larry; Roumeliotis, Stergios

    2005-01-01

    A software system for autonomous operation of a Mars rover is composed of several key algorithms that enable the rover to accurately follow a designated path, compensate for slippage of its wheels on terrain, and reach intended goals. The techniques implemented by the algorithms are visual odometry, full vehicle kinematics, a Kalman filter, and path following with slip compensation. The visual-odometry algorithm tracks distinctive scene features in stereo imagery to estimate rover motion between successively acquired stereo image pairs, by use of a maximum-likelihood motion-estimation algorithm. The full-vehicle kinematics algorithm estimates motion, with a no-slip assumption, from measured wheel rates, steering angles, and angles of rockers and bogies in the rover suspension system. The Kalman filter merges data from an inertial measurement unit (IMU) and the visual-odometry algorithm. The merged estimate is then compared to the kinematic estimate to determine whether and how much slippage has occurred. The kinematic estimate is used to complement the Kalman-filter estimate if no statistically significant slippage has occurred. If slippage has occurred, then a slip vector is calculated by subtracting the current Kalman filter estimate from the kinematic estimate. This slip vector is then used, in conjunction with the inverse kinematics, to determine the wheel velocities and steering angles needed to compensate for slip and follow the desired path.

  5. Scaling analysis for the investigation of slip mechanisms in nanofluids

    PubMed Central

    2011-01-01

    The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it. PMID:21791036

  6. Spontaneous, large stick-slip events in rotary-shear experiments as analogous to earthquake rupture

    NASA Astrophysics Data System (ADS)

    Zu, Ximeng; Reches, Zeev

    2015-04-01

    Experimental stick-slips are commonly envisioned as laboratory analogues of the spontaneous faults slip during natural earthquakes (Brace & Byerlee, 1966). However, typical experimental stick-slips are tiny events of slip distances up to a few tens of microns. To close the gap between such events and natural earthquakes, we develop a new method that produces spontaneous stick-slips with large displacements on our rotary shear apparatus (Reches & Lockner, 2010). In this method, the controlling program continuously calculates the real-time power-density (PD = slip-velocity times shear stress) of the experimental fault. Then, a feedback loop modifies the slip-velocity to match the real-time PD with the requested PD. In this method, the stick-slips occur spontaneously while slip velocity and duration are not controlled by the operator. We present a series of tens stick-slip events along granite and diorite experimental faults with 0.0001-1.3 m of total slip and slip-velocity up to 0.45 m/s. Depending on the magnitude of the requested PD, we recognized three types of events: (1) Stick-slips with a nucleation slip that initiates ~0.1 sec before the main slip which is characterized by temporal increase of shear stress, normal stress, and fault dilation; (2) Events resembling slip-pulse behavior of abrupt acceleration and intense dynamic weakening and subsequent strength recovery; and (3) Small, creep events during quasi-continuous, low- velocity slip with tiny changes of stress and dilation. The energy-displacement catalog of types (1) and (2) events shows good agreement with previous slip-pulse experiments and natural earthquakes (Chang et al., 2012). The present experiments indicate that power-density control is a promising experimental approach for earthquake simulations.

  7. Mechanics of Suture Joints

    NASA Astrophysics Data System (ADS)

    Li, Yaning; Song, Juha; Ortiz, Christine; Boyce, Mary; Ortiz group/DMSE/MIT Team; Boyce group/ME/MIT Team

    2011-03-01

    Biological sutures are joints which connect two stiff skeletal or skeletal-like components. These joints possess a wavy geometry with a thin organic layer providing adhesion. Examples of biological sutures include mammalian skulls, the pelvic assembly of the armored fish Gasterosteus aculeatus (the three-spined stickleback), and the suture joints in the shell of the red-eared slider turtle. Biological sutures allow for movement and compliance, control stress concentrations, transmit loads, reduce fatigue stress and absorb energy. In this investigation, the mechanics of the role of suture geometry in providing a naturally optimized joint is explored. In particular, analytical and numerical micromechanical models of the suture joint are constructed. The anisotropic mechanical stiffness and strength are studied as a function of suture wavelength, amplitude and the material properties of the skeletal and organic components, revealing key insights into the optimized nature of these ubiquitous natural joints.

  8. Slip flow over structured surfaces with entrapped microbubbles

    E-print Network

    Jari Hyväluoma; Jens Harting

    2008-05-26

    On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip to appear due to the increased roughness. The simulation method used allows the bubbles to deform due to viscous stresses. We find a decrease of the detected slip with increasing shear rate which is in contrast to some recent experimental results implicating that bubble deformation cannot account for these experiments. Possible applications of bubble surfaces in microfluidic devices are discussed.

  9. Spreading of Fluids on Solids Under Pressure: Effect of Slip

    E-print Network

    Soma Nag; Tapati Dutta; Sujata Tarafdar

    2010-05-28

    Spreading of different types of fluid on substrates under an impressed force is an interesting problem. Here we study spreading of four fluids, having different hydrophilicity and viscosity on two substrates - glass and perspex, under an external force. The area of contact of fluid and solid is video-photographed and its increase with time is measured. The results for different external forces can be scaled onto a common curve. We try to explain the nature of this curve on the basis of existing theoretical treatment where either the no-slip condition is used or slip between fluid and substrate is introduced. We find that of the eight cases under study, in five cases quantitative agreement is obtained using a slip coefficient.

  10. Atomistic Determination of Cross-Slip Pathway and Energetics

    SciTech Connect

    Rasmussen, T.; Jacobsen, K.W.; Jonsson, H. [CAMP, Department of Physics, Technical University of Denmark, DK--2800 Lyngby (Denmark)] [CAMP, Department of Physics, Technical University of Denmark, DK--2800 Lyngby (Denmark); Rasmussen, T.; Leffers, T.; Pedersen, O.B. [Materials Research Department, Riso/ National Laboratory, DK--4000 Roskilde (Denmark)] [Materials Research Department, Riso/ National Laboratory, DK--4000 Roskilde (Denmark); Srinivasan, S.G. [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 89195-2120 (United States)] [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 89195-2120 (United States); Jonsson, H. [Department of Chemistry, University of Washington, Seattle, Washington 89195--1700 (United States)] [Department of Chemistry, University of Washington, Seattle, Washington 89195--1700 (United States)

    1997-11-01

    The mechanism for cross slip of a screw dislocation in Cu is determined by atomistic simulations that only presume the initial and final states of the process. The dissociated dislocation constricts in the primary plane and redissociates into the cross-slip plane while still partly in the primary plane. The transition state and activation energy for cross slip as well as the energies of the involved dislocation constrictions are determined. One constriction has a negative energy compared to parallel partials. The energy vs splitting width for recombination of parallel partials into a perfect dislocation is determined. The breakdown of linear elasticity theory for small splitting widths is studied. {copyright} {ital 1997} {ital The American Physical Society}

  11. Superplastic flow lubricates carbonate faults during earthquake slip

    NASA Astrophysics Data System (ADS)

    De Paola, Nicola; Holdsworth, Robert; Viti, Cecilia; Collettini, Cristiano; Faoro, Igor; Bullock, Rachael

    2014-05-01

    Tectonic earthquakes are hosted in the shallower portion of crustal fault zones, where fracturing and cataclasis are thought to be the dominant processes during frictional sliding. Aseismic shear in lower crust and lithospheric mantle shear zones is accomplished by crystal plasticity, including superplastic flow acting at low strain rates on ultrafine-grained rocks. Superplasticity has also been observed at high strain rates for a range of nano-phase alloys and ceramics, and could potentially occur in fine-grained geological materials, if deformed at high strain rates and temperatures. We performed a set of displacement-controlled experiments to explore whether superplastic flow can effectively weaken faults, and facilitate earthquake propagation. The experiments were performed on fine-grained synthetic gouges (63 < f < 93 ?m) of undeformed, protolith carbonate rocks using a rotary shear apparatus, at target speed v = 1 ms-1, normal stresses ?n = 12-18 MPa, displacements d from 0.009 to 1.46 m, room temperature and humidity conditions. Samples were recovered after each experiment to study the slip zone microstructures. The integration of experimental data and microstructural observations shows that during sliding at seismic velocity, brittle fracturing and cataclasis control shear localization and grain size reduction in the slip zone at relatively low temperatures (T ? 100 °C). Stress levels predicted by such behaviours match those measured during the experiments. As temperatures rise due to frictional heating (T ? 500 °C), dislocation creep mechanisms start to accommodate intragranular strain, and play a key role in producing nanoscale subgrains (< 200 nm) in the slip zone. At this stage, despite of the presence of nanoparticles in the slip zone and the attainment of seismic slip rates, the measured frictional strength of experimental faults still lies within Byerlee's range of values ? = 0.8. This suggests that the slip zone bulk strength at this stage is controlled by cataclastic frictional sliding rather than by dislocation creep or nanopowder lubrication mechanisms. When T ? 800 °C are attained, micro-textures diagnostic of diffusion-dominated grain boundary sliding are widespread within the slip zone, and suggest bulk superplastic flow. Flow stresses predicted by superplasticity constitutive laws at the slip zone temperatures, grain sizes and strain rates attained during the experiments match those we measured in the laboratory (? = 0.16). We propose therefore that the activation of diffusion creep at high temperatures (T ? 800 °C) leads to slip zone-localised superplastic flow and that this causes the dynamic weakening of carbonate faults at seismic slip rates. Note, however, that both cataclasis and dislocation creep operating at lower temperatures, during the earlier stages of slip, are critical, precursory processes needed to produce the nanoscale grain sizes required to activate grainsize sensitive mechanisms during superplastic flow. Finally, the re-strengthening observed during the decelerating phase of deformation can be explained by the falling temperature "switching off" slip zone-localized superplasticity, leading to a return to frictional sliding. These results indicate that superplastic flow can effectively weaken faults, and facilitate earthquake propagation in the upper crust.

  12. Preliminary soil-slip susceptibility maps, southwestern California

    USGS Publications Warehouse

    Morton, Douglas M.; Alvarez, Rachel M.; Campbell, Russell H.; Digital preparation by Bovard, Kelly R.; Brown, D.T.; Corriea, K.M.; Lesser, J.N.

    2003-01-01

    This group of maps shows relative susceptibility of hill slopes to the initiation sites of rainfall-triggered soil slip-debris flows in southwestern California. As such, the maps offer a partial answer to one part of the three parts necessary to predict the soil-slip/debris-flow process. A complete prediction of the process would include assessments of “where”, “when”, and “how big”. These maps empirically show part of the “where” of prediction (i.e., relative susceptibility to sites of initiation of the soil slips) but do not attempt to show the extent of run out of the resultant debris flows. Some information pertinent to “when” the process might begin is developed. “When” is determined mostly by dynamic factors such as rainfall rate and duration, for which local variations are not amenable to long-term prediction. “When” information is not provided on the maps but is described later in this narrative. The prediction of “how big” is addressed indirectly by restricting the maps to a single type of landslide process—soil slip-debris flows. The susceptibility maps were created through an iterative process from two kinds of information. First, locations of sites of past soil slips were obtained from inventory maps of past events. Aerial photographs, taken during six rainy seasons that produced abundant soil slips, were used as the basis for soil slip-debris flow inventory. Second, digital elevation models (DEM) of the areas that were inventoried were used to analyze the spatial characteristics of soil slip locations. These data were supplemented by observations made on the ground. Certain physical attributes of the locations of the soil-slip debris flows were found to be important and others were not. The most important attribute was the mapped bedrock formation at the site of initiation of the soil slip. However, because the soil slips occur in surficial materials overlying the bedrocks units, the bedrock formation can only serve as a surrogate for the susceptibility of the overlying surficial materials. The maps of susceptibility were created from those physical attributes learned to be important from the inventories. The multiple inventories allow a model to be created from one set of inventory data and evaluated with others. The resultant maps of relative susceptibility represent the best estimate generated from available inventory and DEM data. Slope and aspect values used in the susceptibility analysis were 10-meter DEM cells at a scale of 1:24,000. For most of the area 10-meter DEMs were available; for those quadrangles that have only 30-meter DEMs, the 30-meter DEMS were resampled to 10-meters to maintain resolution of 10-meter cells. Geologic unit values used in the susceptibility analysis were five-meter cells. For convenience, the soil slip susceptibility values are assembled on 1:100,000-scale bases. Any area of the 1:100,000-scale maps can be transferred to 1:24,000-scale base without any loss of accuracy. Figure 32 is an example of part of a 1:100,000-scale susceptibility map transferred back to a 1:24,000-scale quadrangle.

  13. Shock slip-relations for thermal and chemical nonequilibrium flows

    NASA Astrophysics Data System (ADS)

    Jinrong, Tang

    1996-05-01

    This paper appears to be the first where the multi-temperature shock slip-relations for the thermal and chemical nonequilibrium flows are derived. The derivation is based on analysis of the influences of thermal nonequilibrium and viscous effects on the mass, momentum and emergy flux balance relations at the shock wave. When the relaxation times for all internal energy modes tend to zero, the multi-tmperature shock slip-relations are converted into single-temperature ones for thermal equilibrium flows. The present results can be applied to flow over vehicles of different geometries with or without angles of attack. In addition, the present single-temperature shock slip-relations are compared with those in the literature, and some defects and limitations in the latter are clarified.

  14. The Effect of Patterned Slip on Micro and Nanofluidic Flows

    E-print Network

    Hendy, S C; Burnell, J

    2005-01-01

    We consider the flow of a Newtonian fluid in a nano or microchannel with walls that have patterned variations in slip length. We formulate a set of equations to describe the effects on an incompressible Newtonian flow of small variations in slip, and solve these equations for slow flows. We test these equations using molecular dynamics simulations of flow between two walls which have patterned variations in wettability. Good qualitative agreement and a reasonable degree of quantitative agreement is found between the theory and the molecular dynamics simulations. The results of both analyses show that patterned wettability can be used to induce complex variations in flow. Finally we discuss the implications of our results for the design of microfluidic mixers using slip.

  15. Active strike-slip faulting in El Salvador, Central America

    NASA Astrophysics Data System (ADS)

    Corti, Giacomo; Carminati, Eugenio; Mazzarini, Francesco; Oziel Garcia, Marvyn

    2005-12-01

    Several major earthquakes have affected El Salvador, Central America, during the Past 100 yr as a consequence of oblique subduction of the Cocos plate under the Caribbean plate, which is partitioned between trench-orthogonal compression and strike-slip deformation parallel to the volcanic arc. Focal mechanisms and the distribution of the most destructive earthquakes, together with geomorphologic evidence, suggest that this transcurrent component of motion may be accommodated by a major strike-slip fault (El Salvador fault zone). We present field geological, structural, and geomorphological data collected in central El Salvador that allow the constraint of the kinematics and the Quaternary activity of this major seismogenic strike-slip fault system. Data suggest that the El Salvador fault zone consists of at least two main ˜E-W fault segments (San Vicente and Berlin segments), with associated secondary synthetic (WNW-ESE) and antithetic (NNW-SSE) Riedel shears and NW-SE tensional structures. The two main fault segments overlap in a dextral en echelon style with the formation of an intervening pull-apart basin. Our original geological and geomorphologic data suggest a late Pleistocene Holocene slip rate of ˜11 mm/yr along the Berlin segment, in contrast with low historical seismicity. The kinematics and rates of deformation suggested by our new data are consistent with models involving slip partitioning during oblique subduction, and support the notion that a trench-parallel component of motion between the Caribbean and Cocos plates is concentrated along E-W dextral strike-slip faults parallel to the volcanic arc.

  16. Reduced Aftershock Productivity in Regions with Known Slow Slip Events

    NASA Astrophysics Data System (ADS)

    Collins, G.; Mina, A.; Richardson, E.; McGuire, J. J.

    2013-12-01

    Reduced aftershock activity has been observed in areas with high rates of aseismic slip, such as transform fault zones and some subduction zones. Fault conditions that could explain both of these observations include a low effective normal stress regime and/or a high temperature, semi-brittle/plastic rheology. To further investigate the possible connection between areas of aseismic slip and reduced aftershock productivity, we compared the mainshock-aftershock sequences in subduction zones where aseismic slip transients have been observed to those of adjacent (along-strike) regions where no slow slip events have been detected. Using the Advanced National Seismic System (ANSS) catalog, we counted aftershocks that occurred within 100 km and 14 days of 112 M>=5.0 slab earthquake mainshocks from January 1980 - July 2013, including 90 since January 2000, inside observed regions of detected slow slip: south central Alaska, Cascadia, the Nicoya Peninsula (Costa Rica), Guerrero (Mexico), and the North Island of New Zealand. We also compiled aftershock counts from 97 mainshocks from areas adjacent to each of these regions using the same criteria and over the same time interval. Preliminary analysis of these two datasets shows an aftershock triggering exponent (alpha in the ETAS model) of approximately 0.8, consistent with previous studies of aftershocks in a variety of tectonic settings. Aftershock productivity for both datasets is less than that of continental earthquakes. Contrasting the two datasets, aftershock productivity inside slow slip regions is lower than in adjacent areas along the same subduction zone and is comparable to that of mid-ocean ridge transform faults.

  17. Towards a spatially and temporally constant Karakorum fault slip rate

    NASA Astrophysics Data System (ADS)

    Chevalier, M.; van der Woerd, J.; Tapponnier, P.; Li, H.; Ryerson, F. J.; Finkel, R. C.

    2012-12-01

    Constraining the Karakorum fault (KF) slip-rate is essential to understand the present-day kinematic role of large strike-slip faults in the deformation of Tibet. The range of geodetic and geologic slip-rates is ~0 - 11 mm/yr. Cumulative offsets of alluvial fans and terrace risers ranging from 38 to 220 m add new quantitative information on its late Quaternary slip-rate. Their ages were determined using 10Be surface-exposure dating of 74 samples collected at 3 alluvial sites along the Bangong - Chaxikang and Gar basin segments, southeast of Bangong Lake. The slip-rate during the 0 - 60 ka period is 2.9(+1.0/-0.6) mm/yr at GUN, >5.3(+4.3/-1.7) mm/yr at CK and >5.3(+3.1/-2.3) mm/yr at GF. These rates are in agreement with those determined to the southeast (>5.5±0.5 mm/yr at Manikala on one strand for the same period, Chevalier et al., 2005a,b; 7.1(+3.2/-1.7) mm/yr at Menshi and 7.9(+3.2/-2.5) mm/yr near Kailas across two strands, Chevalier et al., 2012) and to the northwest (4±1 mm/yr at Tangste, Brown et al., 2002; >5 mm/yr at Muji, Chevalier et al., 2011b, both on one strand, during the Holocene). We suggest that the minimum late Quaternary slip-rate along the entire length of the KF may be relatively constant along-strike at >5 mm/yr on one fault branch or >7 mm/yr across two branches. In addition to being spatially constant, this late Quaternary rate appears to be, within error, in agreement with most studies at various timescales and suggests that at first approximation, no major discrepancy exists between geodetic and geologic rates.

  18. Slip asymmetries and rotational defects in Cyclotrimethylene trinitramine (RDX)

    NASA Astrophysics Data System (ADS)

    Picu, Catalin; Pal, Anirban; Mathew, Nithin

    2014-03-01

    In this work we study the motion of dislocations and formation of point defects in the molecular crystal Cyclomethylene trinitramine (RDX) by means of atomistic simulations. We show that slip asymmetries exist in this crystal, i.e. dislocations in given slip system can move easier in one direction than in the other, and this effect is due to the steric hindrance of molecules. The effect can be correlated with the presence of a new type of point defects which are molecules placed in a rotated position relative to the perfect crystal configuration. The stability of these rotational point defects is discussed. Support from the ARO is gratefully acknowledged.

  19. Stick-slip instability for viscous fingering in a gel

    NASA Astrophysics Data System (ADS)

    Puff, N.; Debrégeas, G.; di Meglio, J.-M.; Higgins, D.; Bonn, D.; Wagner, C.

    2002-05-01

    The growth dynamics of an air finger injected in a visco-elastic gel (a PVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the standard Saffman-Taylor instability, we observe—with increasing finger velocities—the existence of two new regimes: (a) a stick-slip regime for which the finger tip velocity oscillates between 2 different values, producing local pinching of the finger at regular intervals; (b) a "tadpole" regime where a fracture-type propagation is observed. A scaling argument is proposed to interpret the dependence of the stick-slip frequency with the measured rheological properties of the gel.

  20. Boutonniere deformity of the second toe after planter dislocation of proximal interphalangeal joint: a case report.

    PubMed

    Yoshino, Nobuyuki; Watanabe, Nobuyoshi; Fujita, Nobuhiko; Fukuda, Yukuhisa; Yamashita, Taku; Fujiwara, Hiroyoshi

    2009-11-01

    The boutonniere deformity is a well-known deformity in the fingers, however, its appearance on a lessor toe is extremely rare. In the present case, the deformity resulted from a rupture of the central slip of the extensor tendon and the shift of the lateral bands to the planter side after reduction of a traumatic planter dislocation of the PIP joint of the second toe. Surgical repair of the extensor mechanism brought good results. PMID:19169694

  1. Rapid kinematic slip inversion with regional geophysical data: towards site-specific tsunami intensity forecasts.

    NASA Astrophysics Data System (ADS)

    Melgar, D.; Bock, Y.

    2014-12-01

    Rapid kinematic slip inversions immediately following earthquake rupture is traditionally limited to teleseismic data and delayed many hours after large events. Regional data such as strong motion is difficult to incorporate quickly into images of the source process because baseline offsets render the long period portion of the recording unreliable. Recently it's been demonstrated that high rate GPS can potentially produce rapid slip inversions for large events but is limited to very long periods. With an example of the 2011 M9 Tohoku-oki event we will demonstrate that the optimal on-the-fly combination of GPS and strong motion through a seismogeodetic Kalman filter produces reliable, broadband strong motion displacement and velocity waveforms that can be used for kinematic inversion. Through joint inversion of displacement and velocity waveforms we will show that it is possible to obtain a broadband image of the source. Furthermore, we will also show that it is possible to include offshore geophysical observables such as sea surface measurements of tsunami propagation from GPS buoys and ocean bottom pressure sensors into the kinematic inversion. These data better constrain the shallowest part of rupture. We will use the time-dependent deformation of bathymetry predicted from the inversion results as an initial condition for tsunami propagation and inundation modeling. Through a comparison to post-event survey observations we will demonstrate that it is possible to reproduce the inundation pattern along the coastline in great detail and argue that detailed site-specific forecast of tsunami intensity is achievable with current methods and instrumentation.

  2. Offset of Latest Pleistocene Shoreface Reveals Slip Rate on the Hosgri Strike-Slip Fault, Offshore Central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Hartwell, S. R.; Dartnell, P.

    2014-12-01

    The Hosgri fault is the southern part of the regional Hosgri-San Gregorio dextral strike-slip fault system, which extends primarily in the offshore region for about 400 km in central California. Between Morro Bay and San Simeon, high-resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by a ~265-m-wide slope interpreted as the shoreface of a relict sand spit that formed during a period of relatively slower sea-level rise (Younger Dryas stadial) in the latest Pleistocene. This sand spit crossed an embayment and connected a western fault-bounded bedrock peninsula and an eastern bedrock highland, a paleogeography similar to modern geomorphology along coastal segments of the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6 ± 0.9 mm/yr. Because the Hosgri fault locally includes an active western strand, and regionally converges with several other faults, this slip rate should be considered a minimum for the Hosgri fault in central California and should not be applied for the entire Hosgri-San Gregorio fault system. This slip rate indicates that the Hosgri system takes up the largest share of the strike-slip fault budget and is the most active strike-slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high-resolution bathymetry in earthquake-hazard characterization of active offshore faults.

  3. Campylobacter Prosthetic Joint Infection

    PubMed Central

    Vasoo, Shawn; Schwab, Jeramy J.; Cunningham, Scott A.; Robinson, Trisha J.; Cass, Joseph R.; Berbari, Elie F.; Walker, Randall C.; Osmon, Douglas R.

    2014-01-01

    A 75-year-old man was diagnosed with probable Campylobacter jejuni prosthetic knee infection after a diarrheal illness. Joint aspirate and operative cultures were negative, but PCR of prosthesis sonicate fluid was positive, as was stool culture. Nineteen additional cases of Campylobacter prosthetic joint infection reported in the literature are reviewed. PMID:24523462

  4. Joint Newspaper Operating Agreements.

    ERIC Educational Resources Information Center

    Parsons, Marie

    The number of competing daily newspapers in American cities has dwindled until only about 50 cities boast two papers. Of the newspapers in those cities, 23 now maintain separate editorial operations but have joint printing, advertising, and circulation departments. The concept of joint operation is 50 years old, dating from the Depression years…

  5. Compound solder joints

    NASA Technical Reports Server (NTRS)

    Batista, R. I.; Simonson, R. B.

    1976-01-01

    Joining technique prevents contamination, may be used to join dissimilar metal tubes, minimizes fluid and gas entrapment, expedites repairs, and can yield joints having leakage rates less than 0.000001 standard cubic cm He/min. Components of joint are solder sleeve, two solder rings, Teflon sleeve, and tubing to be joined.

  6. Acromioclavicular joint disease.

    PubMed

    Mcdonald, Scott; Hopper, Melanie A

    2015-07-01

    The acromioclavicular joint is an important component of the shoulder girdle experiencing significant loading during normal activities of daily living. The joint is frequently subjected to trauma and as a synovial articulation can become involved in rheumatoid arthritis and the seronegative arthropathies. PMID:26021590

  7. Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions

    USGS Publications Warehouse

    Becker, T.W.; Hardebeck, J.L.; Anderson, G.

    2005-01-01

    We use Global Positioning System (GPS) velocities and stress orientations inferred from seismicity to invert for the distribution of slip on faults in the southern California plate-boundary region. Of particular interest is how long-term slip rates are partitioned between the Indio segment of the San Andreas fault (SAF), the San Jacinto fault (SJF) and the San Bernardino segment of the SAE We use two new sets of constraints to address this problem. The first is geodetic velocities from the Southern California Earthquake Center's (SCEC) Crustal Motion Map (version 3 by Shen et al.), which includes significantly more data than previous models. The second is a regional model of stress-field orientations at seismogenic depths, as determined from earthquake focal mechanisms. While GPS data have been used in similar studies before, this is the first application of stress-field observations to this problem. We construct a simplified model of the southern California fault system, and estimate the interseismic surface velocities using a backslip approach with purely elastic strain accumulation, following Meade et al. In addition, we model the stress orientations at seismogenic depths, assuming that crustal stress results from the loading of active faults. The geodetically derived stressing rates are found to be aligned with the stress orientations from seismicity. We therefore proceed to invert simultaneously GPS and stress observations for slip rates of the faults in our network. We find that the regional patterns of crustal deformation as imaged by both data sets can be explained by our model, and that joint inversions lead to better constrained slip rates. In our preferred model, the SJF accommodates ???15 mm yr-1 and the Indio segment of the SAF ???23 mm yr-1 of right-lateral motion, accompanied by a low slip rate on the San Bernardino segment of the SAF 'Anomalous' fault segments such as around the 1992 Mw = 7.3 Landers surface rupture can be detected. There, observed stresses deviate strongly from the long-term loading as predicted by our simple model. Evaluation of model misfits together with information from palaeoseismology may provide further insights into the time dependence of strain accumulation along the San Andreas system. ?? 2004 RAS.

  8. EXPERIMENTAL ANALYSIS OF GROUNDWATER FLOW THROUGH A LANDSLIDE SLIP SURFACE USING NATURAL AND ARTIFICIAL WATER

    E-print Network

    Paris-Sud XI, Université de

    of slip surfaces induces a heterogeneity, where mechanical and hydrogeological properties are modified. Groundwater flows are characterized, using hydro-geochemical methods. The surface deformation is recordedEXPERIMENTAL ANALYSIS OF GROUNDWATER FLOW THROUGH A LANDSLIDE SLIP SURFACE USING NATURAL

  9. Landslide subsurface slip geometry inferred from 3-D surface displacement fields

    NASA Astrophysics Data System (ADS)

    Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.

    2015-03-01

    The stability of many large landslides is determined in part by deformation along buried, often inaccessible, slip surfaces. Factors such as infiltrating rainfall on the slip surface lead to stability changes. Yet characterizing the depth and shape of this slip surface is challenging. Here we examine the hypothesis that the subsurface slip geometry can be constrained by ground surface displacements in concert with two, mechanically distinct, forward models. We estimate a 3-D ground displacement field for the slow-moving Cleveland Corral landslide in California using repeat terrestrial laser scanner data. We test the efficacy of two models to estimate slip depth and slip magnitude of the slide—a 2-D balanced cross-section method and an elastic dislocation model. The estimated slip surface depth using both methods matches in situ observations from shear rods installed in the slide within the ±0.45 m misfit indicating that these are valuable approaches for investigating landslide geometry and slip behavior.

  10. arXiv:condmat/0306345 Boundary Slip as a Result of a Prewetting Transition

    E-print Network

    Dünweg, Burkhard

    the slip length. Therefore, it is not surprising that the slippage e#11;ect has not been detected velocity at the solid, it is possible to allow for an amount of slippage, described by a slip length b

  11. Role of friction-induced torque in stick-slip motion J. Scheibert1

    E-print Network

    Paris-Sud XI, Université de

    the position in the interface. As the shear force is increased, a slip region nucleates at the first point on a plane) the transition is smooth. As the shear force is increased, micro-slip occurs immediately

  12. Coseismic and early postseismic slip of the 2014 South Napa earthquake from ABIC-based modeling of campaign GPS and InSAR data

    NASA Astrophysics Data System (ADS)

    Funning, G.; Floyd, M.; Swiatlowski, J.; Herring, T.; Murray, J. R.; Svarc, J. L.; Johanson, I. A.; Yun, S. H.

    2014-12-01

    The August 24, 2014 South Napa, CA earthquake caused extensive surface rupture of a ~15 km zone along the western edge of Napa valley, including portions of the previously mapped West Napa fault. In the days following the event, growing offsets in cultural features crossing the main rupture strand indicated the occurrence of significant shallow afterslip. Here we use near-field campaign GPS data and InSAR data that closely bracket the earthquake and its early postseismic period to constrain models of the slip on that fault during and after the event. A joint inverse modeling approach based upon Akaike's Bayesian Information Criterion (ABIC) is used to optimally weight the contributions of each dataset and the smoothing constraint that we apply. Our model inputs are: (i) a GPS dataset, comprising pre-event data collected in campaign mode six weeks before the mainshock and three weeks of post-event data starting 8-36 hours after the mainshock collected in semi-continuous mode, from sites at distances 2-20 km from the rupture; and (ii) quadtree-downsampled InSAR data from both descending and ascending passes of the COSMO-SkyMed satellite constellation (first post-event acquisitions made 3 and 10 days after the mainshock, respectively). The former provide strong control on the timing of fault slip, the latter provide strong spatial constraints on fault location and geometry. Preliminary results indicate that the majority of coseismic slip occurred on a NNW-striking subvertical fault plane whose location is consistent with the mapped main surface rupture strand. The pattern of slip shallows significantly from the hypocenter along-strike to the NNW, peaking at ~1 m of slip at depths of 2-4 km, ~8 km NNW of the hypocenter.

  13. Heel contact dynamics during slip events on level and inclined surfaces

    Microsoft Academic Search

    Rakié Cham; Mark S Redfern

    2002-01-01

    This study describes heel contact dynamics during slip events, information that must be known to develop biomechanically relevant shoe-floor coefficient of friction measurement systems. Sixteen subjects walked on a level, 5 and 10° ramp with two possible contaminants (dry, oil). Foot motion was recorded at 350 Hz and compared among no-slip, slip-recovery and slip-fall events. For all trials, the foot

  14. Slip detection by tactile sensors: algorithms and experimental results

    Microsoft Academic Search

    E. G. M. Holweg; H. Hoeve; W. Jongkind; L. Marconi; C. Melchiorri; C. Bonivento

    1996-01-01

    Two techniques for slip detection with a rubber-based tactile matrix sensor are presented. The described results have been obtained within a common research activity between the Robotics and Automation Laboratory of the University of Bologna and the Control Laboratory of the Delft University of Technology. The first technique is based on a frequency analysis of the position of the center

  15. Micro-vibration-based slip detection in tactile force sensors.

    PubMed

    Fernandez, Raul; Payo, Ismael; Vazquez, Andres S; Becedas, Jonathan

    2014-01-01

    Tactile sensing provides critical information, such as force, texture, shape or temperature, in manipulation tasks. In particular, tactile sensors traditionally used in robotics are emphasized in contact force determination for grasping control and object recognition. Nevertheless, slip detection is also crucial to successfully manipulate an object. Several approaches have appeared to detect slipping, the majority being a combination of complex sensors with complex algorithms. In this paper, we deal with simplicity, analyzing how a novel, but simple, algorithm, based on micro-vibration detection, can be used in a simple, but low-cost and durable, force sensor. We also analyze the results of using the same principle to detect slipping in other force sensors based on flexible parts. In particular, we show and compare the slip detection with: (i) a flexible finger, designed by the authors, acting as a force sensor; (ii) the finger torque sensor of a commercial robotic hand; (iii) a commercial six-axis force sensor mounted on the wrist of a robot; and (iv) a fingertip piezoresistive matrix sensor. PMID:24394598

  16. Evaluation of a slip-resistance test for shoes

    Microsoft Academic Search

    M. P. WILSON; P. J. PERKINS

    1985-01-01

    A laboratory test has been developed to measure Static and dynamic friction between shoe sole and floor surface. Good overall agreement was found between this test and a ramp test. The latter involves wearers ascending and descending a slope, the angle of which is increased until slipping occurs. Results indicate that the laboratory lest is relevant to wear conditions.In some

  17. Interfacial Slip in Entrained Soap Films Containing Associating Hydrosoluble Polymer

    E-print Network

    Troian, Sandra M.

    Interfacial Slip in Entrained Soap Films Containing Associating Hydrosoluble Polymer Eric A deviations from this scaling at low Ca, especially for associating surfactant-polymer solutions. We report for the associating pair SDS/PEO over a large range in polymer molecular weight. Comparison of our experimental

  18. [Slip casting of stainless steel powder (author's transl)].

    PubMed

    Okawa, S; Ota, M; Kondo, S

    1976-01-01

    Slip casting of stainless steel powder (AISI type 316 L) was investigated as means of forming medical and dental porous restorations. This research was undertaken to evaluate the effects of the particle size and aging of casting slip and firing conditions. Bulk density was used as a measure of the degree of sintering. Water contents of casting bodies decreased with the particle size and its casting rates, bulk densities and bending strengths increased. Aging of slip decreased casting rates, water contents and bending strengths of the casts. The bulk densities of the sintered stainless steel increased with sintering time and temperature. The porosities of the materials decreased with the particle size and the elevating temperature. The bending strengths of the materials increased sharply with the decreasing particle size. The optical micrographs did not always show the uniform elimination of pores in the sintered. Aging of slip increased a little the bulk densities of the materials and decreased the porosity and the bending strength. PMID:772143

  19. When Malaria Slips a Vaccine's Net Caitlin Sedwick*

    E-print Network

    Read, Andrew

    , causing people to develop antibodies that bind to the protein. Such vaccines may be ``leaky''; they may the parasite more virulent--that is, able to cause more severe disease symptoms or higher death rates in non-vaccinatedSynopsis When Malaria Slips a Vaccine's Net Caitlin Sedwick* Freelance Science Writer, San Diego

  20. Learning and Prediction of Slip from Visual Information

    E-print Network

    Perona, Pietro

    a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Journal of Field Robotics 24(3), 205­231 (2007) © 2007 Wiley Periodicals, Inc. Published online in Wiley is a measure of the lack of progress of a wheeled ground robot while driving. High levels of slip can

  1. A gripper and sensor system for controlled slip and force

    Microsoft Academic Search

    Andreas Rupp; S. A. Velastin

    1994-01-01

    The paper describes the development of a robot gripper, sensors and associated electronics suitable for controlling slippage and contact force. A typical application is the handling of glass test tubes in an automated medical analysis laboratory. Through force control, the gripper first holds an object, then repeatedly releases and regrasps it for controlled slip. The basic mechanical principle consists of

  2. Preliminary slip history of the 2002 Denali earthquake

    Microsoft Academic Search

    C. Ji; D. V. Helmberger; D. J. Wald

    2002-01-01

    Rapid slip histories for the 2002 Denali earthquake were derived from the IRIS global data before geologists arrived in the field. We were able to predict many of the features they observed. Three models were produced indicating a step-wise improvement in matching the waveform data applying a formalism discussed in Ji et al. (2002). The first model referred to as

  3. Analysing earthquake slip models with the spatial prediction comparison test

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Mai, P. Martin; Thingbaijam, Kiran K. S.; Razafindrakoto, Hoby N. T.; Genton, Marc G.

    2015-01-01

    Earthquake rupture models inferred from inversions of geophysical and/or geodetic data exhibit remarkable variability due to uncertainties in modelling assumptions, the use of different inversion algorithms, or variations in data selection and data processing. A robust statistical comparison of different rupture models obtained for a single earthquake is needed to quantify the intra-event variability, both for benchmark exercises and for real earthquakes. The same approach may be useful to characterize (dis-)similarities in events that are typically grouped into a common class of events (e.g. moderate-size crustal strike-slip earthquakes or tsunamigenic large subduction earthquakes). For this purpose, we examine the performance of the spatial prediction comparison test (SPCT), a statistical test developed to compare spatial (random) fields by means of a chosen loss function that describes an error relation between a 2-D field (`model') and a reference model. We implement and calibrate the SPCT approach for a suite of synthetic 2-D slip distributions, generated as spatial random fields with various characteristics, and then apply the method to results of a benchmark inversion exercise with known solution. We find the SPCT to be sensitive to different spatial correlations lengths, and different heterogeneity levels of the slip distributions. The SPCT approach proves to be a simple and effective tool for ranking the slip models with respect to a reference model.

  4. Stabilizing Stick-Slip Friction Rosario Capozza,1

    E-print Network

    Fineberg, Jay

    , that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition generated by either tidal forcing or other very remote earthquakes [10]. These questions motivated studies onset with the phase locking related to a forced transition between slow to fast rupture modes. Our

  5. Intragranular plastic slip heterogeneities: Discrete vs. Mean Field approaches

    Microsoft Academic Search

    S. Berbenni; M. Berveiller; T. Richeton

    2008-01-01

    In this paper, we derive the mechanical fields (internal stresses, elastic energy) arising from the presence of an inelastic distortion field representing a typical intra-granular “microstructure” as the one observed during the plastification of metallic polycrystals. This “microstructure” is due to the formation of discrete intra-granular plastic slip heterogeneities characterized by at least two internal lengths: the first one is

  6. On the elementary relation between pitch, slip, and propulsive efficiency

    NASA Technical Reports Server (NTRS)

    Froude, W

    1920-01-01

    The author examines the current theory on the importance of reducing slip in airplane propellers. The author feels an exaggerated importance is attached to this supposition and feels that the increase in friction by an increase in propeller area or number of revolutions can't be discounted.

  7. Boundary slip in Newtonian liquids: a review of experimental studies

    Microsoft Academic Search

    Chiara Neto; Drew R. Evans; Elmar Bonaccurso; Hans-Jürgen Butt; Vincent S. J. Craig

    2005-01-01

    For several centuries fluid dynamics studies have relied upon the assumption that when a liquid flows over a solid surface, the liquid molecules adjacent to the solid are stationary relative to the solid. This no-slip boundary condition (BC) has been applied successfully to model many macroscopic experiments, but has no microscopic justification. In recent years there has been an increased

  8. Slip Control System for a Deep-Sea Mining Machine

    Microsoft Academic Search

    K. Herzog; E. Schulte; M. A. Atmanand; W. Schwarz

    2007-01-01

    Tracked vehicles capable of locomotion in the deep sea are used for manganese nodule mining. This requires specific technical solutions in various respects. Locomotion in the soft sea bed is one of them. For the Crawler to safely maneuver, an automatic drive mode with slip control of the driving tracks is essential. Based on experimental studies at IKS, University of

  9. Coherent phase slip in arrays of underdamped Josephson tunnel junctions

    SciTech Connect

    van der Zant, H.S.J.; Muller, C.J.; Geerligs, L.J.; Harmans, C.J.P.M.; Mooij, J.E.

    1988-09-01

    In hysteretic I-V characteristics of two-dimensional Josephson junction arrays resistance steps are observed. These steps are explained by switching the whole array into a coherent phase-slip state of rows of junctions across the whole array.

  10. Pressure slip casting of bimodal silicon carbide powder suspensions

    Microsoft Academic Search

    J. M. F Ferreira; H. M. M Diz

    1999-01-01

    Two silicon carbide powders with different particle size distributions were blended in various proportions and then dispersed in aqueous media with a deflocculant. Bodies were consolidated from these suspensions via pressure slip casting. The relative density and the water content of the green bodies were measured and the optimum body in terms of packing ability was then chosen to evaluate

  11. Research on traction slip control algorithm for parallel hybrid cars

    Microsoft Academic Search

    Liang Chu; Li Bo Chao; Zhan Wu; Tong Bo Wu

    2011-01-01

    Traction slip control algorithm and strategy for parallel hybrid vehicle are proposed in this paper. Based on the torque distribution strategy of parallel cars, the torque control strategy and algorithm and brake control strategy of TCS are designed. Under the environment of Matlab\\/Simulink, the vehicle model and TCS controller model of parallel Hybrid Electric vehicle are built. The simulation test

  12. An Analysis of Strain Accumulation on a Strike Slip Fault

    Microsoft Academic Search

    D. L. Turcotte; D. A. Spence

    1974-01-01

    An analysis of strain accumulation on a strike slip fault is given. The fault between two lithospheric plates is assumed to be locked tb a finite depth; owing to plastic flow the fault is free to slide at greaier depths. The base of each plate is also a free boundary. The periodic stress accumulation andtress release associated with the elastic

  13. Slip and flow dynamics of polydisperse thin polystyrene films.

    NASA Astrophysics Data System (ADS)

    Sabzevari, Seyed Mostafa; McGraw, Joshua D.; Jacobs, Karin; Wood-Adams, Paula M.

    2015-03-01

    We investigate the slip of binary and ternary mixtures of nearly monodisperse polystyrene samples on Teflon-coated (AF2400) silicon wafers using dewetting experiments. Binary mixtures of long and short chains along with ternary mixtures with a fixed weight-average molecular weight Mw but different number-average molecular weight Mn were prepared. Thin films of ca. 200 nm were spin coated on mica from polymer solutions and transferred to Teflon substrates. Above the glass transition temperature Tg the films break up via nucleation and growth of holes. The hole growth rate and rim morphology are monitored as a function of Mn and annealing protocol of the films before transfer to Teflon substrates. Slip properties, accessed using hydrodynamic models, and flow dynamics are then examined and compared. We found that the rim morphology and slip of polystyrene blends on Teflon depends on the molecular weight distribution. Similarly, flow dynamics is affected by the presence of short chains in mixture. Moreover, we can provoke differences in slip by choosing appropriate annealing and film transfer protocols for PS films that have first been spin cast on mica surfaces.

  14. Regional Slip Tendency Analysis of the Great Basin Region

    DOE Data Explorer

    Faulds, James E.

    - The resulting along?fault and fault?to?fault variation in slip or dilation potential is a proxy for along fault and fault?to?fault variation in fluid flow conduit potential. Stress Magnitudes and directions were calculated across the entire Great Basin. Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson?Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005). The minimum horizontal stress direction (Shmin) was contoured, and spatial bins with common Shmin directions were calculated. Based on this technique, we subdivided the Great Basin into nine regions (Shmin <070, 070140). Slip and dilation tendency were calculated using 3DStress for the faults within each region using the mean Shmin for the region. Shmin variation throughout Great Basin are shown on Figure 3. For faults within the Great Basin proper, we applied a normal faulting stress regime, where the vertical stress (sv) is larger than the maximum horizontal stress (shmax), which is larger than the minimum horizontal stress (sv>shmax>shmin). Based on visual inspection of the limited stress magnitude data in the Great Basin, we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46. These values are consistent with stress magnitude data at both Dixie Valley (Hickman et al., 2000) and Yucca Mountain (Stock et al., 1985). For faults within the Walker Lane/Eastern California Shear Zone, we applied a strike?slip faulting stress, where shmax > sv > shmin. Upon visual inspection of limited stress magnitude data from the Walker Lane and Eastern California Shear zone, we chose values such that SHmin/SHmax = .46 and Shmin/Sv= .527 representative of the region. Results: The results of our slip and dilation tendency analysis are shown in Figures 4 (dilation tendency), 5 (slip tendency) and 6 (slip tendency + dilation tendency). Shmin varies from northwest to east?west trending throughout much of the Great Basin. As such, north? to northeast?striking faults have the highest tendency to slip and to dilate, depending on the local trend of shmin. These results provide a first order filter on faults and fault systems in the Great Basin, affording focusing of local?scale exploration efforts for blind or hidden geothermal resources.

  15. Airborne Antenna System for Minimum-Cycle-Slip GPS Reception

    NASA Technical Reports Server (NTRS)

    Wright, C. Wayne

    2009-01-01

    A system that includes a Global Positioning System (GPS) antenna and associated apparatus for keeping the antenna aimed upward has been developed for use aboard a remote-sensing-survey airplane. The purpose served by the system is to enable minimum- cycle-slip reception of GPS signals used in precise computation of the trajectory of the airplane, without having to restrict the airplane to maneuvers that increase the flight time needed to perform a survey. Cycle slip signifies loss of continuous track of the phase of a signal. Minimum-cycle-slip reception is desirable because maintaining constant track of the phase of the carrier signal from each available GPS satellite is necessary for surveying to centimeter or subcentimeter precision. Even a loss of signal for as short a time as a nanosecond can cause cycle slip. Cycle slips degrade the quality and precision of survey data acquired during a flight. The two principal causes of cycle slip are weakness of signals and multipath propagation. Heretofore, it has been standard practice to mount a GPS antenna rigidly on top of an airplane, and the radiation pattern of the antenna is typically hemispherical, so that all GPS satellites above the horizon are viewed by the antenna during level flight. When the airplane must be banked for a turn or other maneuver, the reception hemisphere becomes correspondingly tilted; hence, the antenna no longer views satellites that may still be above the Earth horizon but are now below the equatorial plane of the tilted reception hemisphere. Moreover, part of the reception hemisphere (typically, on the inside of a turn) becomes pointed toward ground, with a consequent increase in received noise and, therefore, degradation of GPS measurements. To minimize the likelihood of loss of signal and cycle slip, bank angles of remote-sensing survey airplanes have generally been limited to 10 or less, resulting in skidding or slipping uncoordinated turns. An airplane must be banked in order to make a coordinated turn. For small-radius, short-time coordinated turns, it is necessary to employ banks as steep as 45 , and turns involving such banks are times and for confining airplanes as closely as possible to areas to be surveyed. The idea underlying the design is that if the antenna can be kept properly aimed, then the incidence of cycle slips caused by loss or weakness of signals can be minimized. The system includes an articulating GPS antenna and associated electronic circuitry mounted under a radome atop an airplane. The electronic circuitry includes a microprocessor-based interface-circuit-and-data-translation module. The system receives data on the current attitude of the airplane from the inertial navigation system of the airplane. The microprocessor decodes the attitude data and uses them to compute commands for the GPS-antenna-articulating mechanism to tilt the antenna, relative to the airplane, in opposition to the roll or bank of the airplane to keep the antenna pointed toward the zenith. The system was tested aboard the hurricane- hunting airplane of the National Oceanic and Atmospheric Administration (NOAA) [see figure] during an 11-hour flight to observe the landfall of Hurricane Bret in late summer of 1999. No bank-angle restrictions were imposed during the flight. Post-flight analysis of the GPS trajectory data revealed that no cycle slip had occurred.considered normal maneuvers. These steep banks are highly desirable for minimizing flight

  16. Friction at Seismic Slip Speeds: Experiments and Theory

    NASA Astrophysics Data System (ADS)

    Brown, K.; Fialko, Y.

    2008-12-01

    We present new experimental data and theory that describe the thermal weakening of fine-grained gouges during earthquake slip. We postulate that particles in fine-grained gouges thermally soften due to an intrinsic decrease in the elastic shear modulus in response to rapid heating of the gouge layer. The temperature dependence of the asperity strength is assumed to obey a modified Watchman's equation. In our model, the velocity dependence of the effective coefficient of friction results from the temperature dependence of the theoretical yield strength of the contact asperities, rather than the sudden loss of the asperity strength at some critical temperature. Temperature of individual asperities depends on highly transient dissipation during asperity contacts ("flash heating") as well as the average temperature of the slip zone (which, unlike flash heating, monotonically increases with slip and depends on normal stress). Eventual contact melting can occur depending on the effective normal stress, slip rate, and total slip. Upon reaching the solidus, the residual contact strength is estimated assuming Couette flow for given particle size, slip rate, and melt rheology. We conducted a series of high-speed friction experiments to test the model predictions. Experimental data indicate that there is a systematic evolution of the friction coefficient from ~0.6-0.7 to as low as 0.2 as velocities increase from 0.03 m/s to 2.5 m/s. The inferred power-law exponent of the velocity dependence is ~(-0.4), and the critical weakening velocity appears to depend on the normal stress, consistent with the hypothesis that the observed velocity dependence of friction stems from thermal softening of the asperities. We infer the characteristic grain size using SEM images of the experimentally produced gouge. The grain sizes appear to be power law distributed with the majority of grains less than 1-5 ?m in diameter. We calculate the temperature evolution within the gouge layer assuming 1-D non-steady heat conduction and complete conversion of mechanical work into heat. The predicted time history of temperature inside the sample is in excellent agreement with the experimentally measured temperature. We use the approach model to calculate the transient heating of individual asperities, and compare the calculated average strength of the asperities to the observed coefficient of friction (assuming that once in high speed motion changes in the true contact area are negligible). The model reasonably well reproduces the overall evolution of dynamic friction with slip velocity. Laboratory data do reveal an important (10-20%) initial weakening over slip distances of the order of 1 m that cannot be readily explained in terms of purely thermal effects. We argue that the observed initial weakening is probably mechanical in part, due to initial dilation of the gouge at slip initiation and progressive localization of slip within the gouge layer.

  17. Optimization of a thermal slip sensor using FEM and dimensional analysis

    Microsoft Academic Search

    Dino Accoto; Maria Teresa Francomano; Antonella Benvenuto; Ciro Luccarelli; Eugenio Guglielmelli

    2010-01-01

    During manipulation tasks it is important to maintain a precise and safe control of the grasping force. Slip detection plays a key role to assure an adequate adaptation of the grasping force, without object damaging. Several approaches to slip detection are currently under investigation. In particular, thermal slip sensors use a detection strategy similar to the one employed in hot

  18. A Review of the Factors Involved in Developing Effective Non-slip Floors for Pigs

    Microsoft Academic Search

    C. I. McKee; J. Dumelow

    1995-01-01

    Slips and falls on slippery surfaces cause injury to pigs. However, the slip-resistance of floors is not a factor that can be viewed in isolation since other characteristics of the floor (abrasion, surface profile and hardness) also contribute to pig injury. While a floor should be slip-resistant, this must not be achieved by modifying its properties in such a way

  19. Kinematics of heelstrike during walking and carrying: implications for slip resistance testing

    Microsoft Academic Search

    Mary Ann Holbein-Jenny; Mark S. Redfern; Dan Gottesman; Don B. Chaffin

    2007-01-01

    Slip resistance measurements of shoes and floors are used to evaluate the potential for slip and fall injuries. These measurements are believed to have increased validity when they more closely reflect actual heelstrike biomechanics during locomotion. The purpose of this study was to describe heelstrike kinematics during load carrying to provide data towards improved slip resistance testing. Foot kinematics during

  20. Nonlinear Observer for Bounded Jacobian Systems, With Applications to Automotive Slip Angle Estimation

    Microsoft Academic Search

    Gridsada Phanomchoeng; Rajesh Rajamani; Damrongrit Piyabongkarn

    2011-01-01

    Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applications, including yaw stability control, rollover prevention, and lane departure avoidance. Sensors that can di- rectly measure slip angle are too expensive for ordinary automotive ap- plications. This technical note develops a new nonlinear observer design technique for estimation of slip angle using inexpensive

  1. Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake

    E-print Network

    Goldfinger, Chris

    dislocation model and test three Cascadia earthquake rupture scenarios: slip partitioned to a splay fault equations on unstructured grids. Our simulations of the 1700 Cascadia tsunami require >12­13 m of peak slip allow an average of 5.2 m of slip per event for 11 additional earthquakes inferred from the southern

  2. Age-related slip avoidance strategy while walking over a known slippery floor surface

    Microsoft Academic Search

    Thurmon E. Lockhart; Jeremy M. Spaulding; Sung Ha Park

    2007-01-01

    When confronted with impending slip\\/fall situations, gait parameters are adjusted accordingly to avoid slipping. This study was conducted to assess age-related slip avoidance strategy by measuring gait parameters and muscle activity characteristics of the lower extremities (hamstrings, calves, and quadriceps) of both young and older participants while ambulating successfully over a known slippery floor surface. Fourteen younger and 14 older

  3. High sensitivity slip sensor using pressure conductive rubber for dexterous grasp and manipulation

    Microsoft Academic Search

    Seiichi Teshigawara; Satoru Shimizu; Takahiro Tsutsumi; Yosuke Suzuki; Aiguo Ming; Makoto Shimojo; Masatoshi Ishikawa

    2010-01-01

    Slip-detecting tactile sensors are essential for achieving human-like gripping motion with a robot hand. In previous research, we developed a flexible, thin and lightweight slip sensor that exploits a resistance change of the pressure conductive rubber. This sensor distinguishes between both contact and initial slip by using a complicated resistance change just before slippage of object is generated. In this

  4. First-Principles Study of Secondary Slip in Zirconium Nermine Chaari and Emmanuel Clouet

    E-print Network

    Paris-Sud XI, Université de

    First-Principles Study of Secondary Slip in Zirconium Nermine Chaari and Emmanuel Clouet CEA, DEN, as found in iridium [8]. Cross slip is also observed in hexagonal close-packed (hcp) metals. In zirconium secondary slip in hcp metals. We fo- cus mainly on zirconium, although we checked that the FIG. 1. Hexagonal

  5. Aseismic slip transients emerge spontaneously in three-dimensional rate and state modeling of

    E-print Network

    Aseismic slip transients emerge spontaneously in three-dimensional rate and state modeling heterogeneous earthquake slip at seismogenic depths, and associated postseismic transients, we found that slip of the seismogenic zone. Both transients which start well after a seismic event, and those which are triggered

  6. An integrated perspective of the continuum between earthquakes and slow-slip phenomena

    NASA Astrophysics Data System (ADS)

    Peng, Zhigang; Gomberg, Joan

    2010-09-01

    The discovery of slow-slip phenomena has revolutionized our understanding of how faults accommodate relative plate motions. Faults were previously thought to relieve stress either through continuous aseismic sliding, or as earthquakes resulting from instantaneous failure of locked faults. In contrast, slow-slip events proceed so slowly that slip is limited and only low-frequency (or no) seismic waves radiate. We find that slow-slip phenomena are not unique to the depths (tens of kilometres) of subduction zone plate interfaces. They occur on faults in many settings, at numerous scales and owing to various loading processes, including landslides and glaciers. Taken together, the observations indicate that slowly slipping fault surfaces relax most of the accrued stresses through aseismic slip. Aseismic motion can trigger more rapid slip elsewhere on the fault that is sufficiently fast to generate seismic waves. The resulting radiation has characteristics ranging from those indicative of slow but seismic slip, to those typical of earthquakes. The mode of seismic slip depends on the inherent characteristics of the fault, such as the frictional properties. Slow-slip events have previously been classified as a distinct mode of fault slip compared with that seen in earthquakes. We conclude that instead, slip modes span a continuum and are of common occurrence.

  7. RESEARCH ARTICLE Volcanic facies architecture of an intra-arc strike-slip

    E-print Network

    Busby, Cathy

    RESEARCH ARTICLE Volcanic facies architecture of an intra-arc strike-slip basin, Santa Rita Glance Conglomerate) to construct a facies model for a strike-slip basin dominated by volcanism the strike-slip fault. In our facies model, the basin fill thins and volcanism decreases markedly away from

  8. Cycle slip Detection in the context of rtK GPs positioning of lightweight UAVs

    E-print Network

    Behnke, Sven

    148 Cycle slip Detection in the context of rtK GPs positioning of lightweight UAVs C. Eling1 , E of a simple test it will be shown that the integration of accelerometers in the RTK GPS float solution allows for a reliable detection and repair of cycle slips. Keywords RTK GPS, UAV, direct georeferencing, cycle slip

  9. Field examples of strike-slip fault terminations in Mongolia and their tectonic significance

    Microsoft Academic Search

    Amgalan Bayasgalan; James Jackson; Jean-François Ritz; Sebastien Carretier

    1999-01-01

    Deformation at the ends of large intracontential strike-slip faults that do not simply link other major structures often involves rotations about a vertical axis. We use earthquake slip vectors, surface rupture in earthquakes, and geomorphology to examine the ends of three major strike-slip faults in Mongolia. In these places a simple pattern is seen, consisting of a thrust fault on

  10. Shearing of ?? precipitates and formation of planar slip bands in Inconel 718 during cyclic deformation

    Microsoft Academic Search

    L. Xiao; D. L. Chen; M. C. Chaturvedi

    2005-01-01

    Fatigue of Inconel 718 at RT and 650°C caused the formation of planar deformation bands and shearing of coherent and ordered ?? and ?? precipitates by paired dislocations. The paired dislocations could not cross-slip, resulting in planar slip and planar slip bands, whose spacing and width were almost independent of the cyclic plastic strain amplitude.

  11. JOINT ELECTRICAL & COMPUTER ENGINEERING AND

    E-print Network

    JOINT ELECTRICAL & COMPUTER ENGINEERING AND PHYSICS COLLOQUIUM "Speckle Statistics, Coherence confirmation of the increase in the well- defined polarization state of the output radiation. In the joint

  12. Distribution of Slip at the Northern Sumatran Fault System

    NASA Technical Reports Server (NTRS)

    Genrich, J. F.; Bock, Y.; McCaffrey, R.; Prawirodirdjo, L.; Stevens, C. W.; Puntodewo, S. S. O.; Subarya, C.; Wdowinski, S.

    2000-01-01

    We model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989-1996 with the Global Positioning System (GPS) as elastic strain across a locked strike-slip fault to infer the contemporary slip rate, locking depth, and location of the Sumatran fault (SF) in northern Sumatra (1 S-3 N). GPS-derived slip rate estimates increase slightly northward from 23 plus or minus 3 mm/yr at 0.8 deg S to 26 plus or minus 2mm/yr at 2.7 N. They agree with geologic estimates north of the Equator, but at 0.5 S they are about 10 mm/yr higher. Strain appears to be distributed asymmetrically about the fault. South of 2 N, about 5 mm/yr of shear is required within the offshore forearc, west of the fault, to achieve a closer agreement of fault locations inferred from GPS velocities with geologically identified traces of the SF. Locking depth estimates are on the order of 10-20 km. The western branch of the major fault bifurcation near 1 N slips at a rate five times higher than the eastern branch. The two main strands of the fault at the northwestern tip of Sumatra (5.5 N) appear to be nearly free of horizontal strain; significant slip must occur away from the two strands, probably further east at two other geologically active branches. The Banda Aceh embayment is extruded to the northwest at a rate of 5 plus or minus 2 mm/yr. Within the estimated velocity uncertainties of several mm/yr, fault-normal deformation along the SF is insignificant. Almost strain free, the northern part of the back-arc basin is part of a rigid Sunda shelf, while the northern forearc is subjected to 8 plus or minus 5 x 10 (exp -8)/yr of extension nearly parallel to the arc.

  13. Thermal Pressurization is Significant During Earthquake Nucleation, Before Seismic Slip

    NASA Astrophysics Data System (ADS)

    Schmitt, S. V.; Segall, P.; Matsuzawa, T.

    2007-12-01

    Shear heating-induced thermal pressurization has long been invoked as a potential weakening mechanism during earthquakes. It is often assumed that thermal pressurization does not become important until earthquakes have reached a critical size. Segall and Rice [2006], however, suggested that thermal effects may become dominant during the quasi-static nucleation phase, well before inertial effects are significant. By neglecting the feedback between pore-pressure change and slip rate, they estimated that thermal pressurization dominates weakening at slip rates in excess of 10-5 to 10-3 m/s. We further explore this problem numerically assuming a planar fault in a 2D elastic medium and accounting for full thermo-mechanical coupling. We include one-dimensional thermal and pore pressure diffusion normal to a fault governed by rate-state friction. Stress rate and fault slip rate are related through a Hilbert transform in the Fourier domain, and the thermal diffusion is computed with an explicit finite difference formulation. For uniform thermal and hydraulic properties, the pore pressure and temperature on the fault are uniquely related [Rice, 2006, JGR], so only one finite difference grid is required in this limit. As the slip rate increases, the temperature gradient adjacent to the fault increases dramatically. We refine the finite difference grid when the error in the spatial derivative exceeds a specified threshold. The radiation damping approximation is used to simulate inertial effects. For a hydraulic diffusivity of 10-6 m2/s---consistent with permeability inferred for some active fault zones-- -we find that results with and without thermal coupling diverge at slip rates substantially less than those estimated by Segall and Rice [2006]. This reinforces the conclusion that thermal pressurization cannot be ignored in earthquake nucleation. For calculations with the aging form of the state evolution equation and a/b = 1/3, the nucleation zone contracts to a smaller size than Dieterich's [1992] result, which ignored thermal effects.

  14. Late Quaternary slip on the Santa Cruz Island fault, California

    USGS Publications Warehouse

    Pinter, N.; Lueddecke, S.B.; Keller, E.A.; Simmons, K.R.

    1998-01-01

    The style, timing, and pattern of slip on the Santa Cruz Island fault were investigated by trenching the fault and by analysis of offset late Quaternary landforms. A trench excavated across the fault at Christi Beach, on the western coast of the island, exposed deformation of latest Pleistocene to Holocene sediments and pre-Quaternary rocks, recording repeated large-magnitude rupture events. The most recent earthquake at this site occurred ca. 5 ka. Coastal terraces preserved on western Santa Cruz Island have been dated using the uranium-series technique and by extrapolation using terrace elevations and the eustatic record. Offset of terraces and other landforms indicates that the Santa Cruz Island fault is predominantly left lateral, having a horizontal slip rate of not more than 1.1 mm/yr and probably about 0.8 mm/yr. The fault also has a smaller reverse component, slipping at a rate of between 0.1 and 0.2 mm/yr. Combined with measurements of slip per event, this information suggests a long-term average recurrence interval of at least 2.7 k.y. and probably 4-5 k.y., and average earthquake magnitudes of Mw 7.2-7.5. Sense of slip, recurrence interval, and earthquake magnitudes calculated here for the Santa Cruz Island fault are very similar to recent results for other faults along the southern margin of the western Transverse Range, including the Malibu Coast fault, the Santa Monica fault, the Hollywood fault, and the Raymond fault, supporting the contention that these faults constitute a continuous and linked fault system, which is characterized by large but relatively infrequent earthquakes.

  15. Dynamic Mechanochemistry of Seismic Slip -Nano Spherules Lubrication

    NASA Astrophysics Data System (ADS)

    Tanaka, H.; Chen, W.; Chen, Y.; Song, Y.; Ma, K.

    2007-12-01

    The Chelungpu fault, which was activated during 1999Chi-Chi Earthquake, had been drilled (Hole A, B and C) to recover the earthquake slip zone materials. We present here the results of nano-scale observations for identified slip zone materials (Ma, Tanaka et al., 2006) by using HR-TEM and TXM technique. Minimum size of grains observed under HR-TEM is 3 nm. The grain size distribution for grains larger than 100 nm in diameter follows the fractal law and grain shape is highly irregular. Grains smaller than100 nm show some specific characteristics, that is, smaller the grains, more the spherical shapes and more equi-granular. Thus, the grains smaller than 100 nm are no longer described by fractal distribution model. By SAD and EDX analysis under HR-TEM, the nano spherules are mainly composed of crystallized quartz associated with minor amounts of carbonates and amorphous materials. Results of observations lead following three conclusions, (1) nano spherules are not generated just by fracturing based on their shapes and grain size distributions. (2) nano spherules would compose viscous materials enveloping larger fractured grains from SEM observations. (3) Mica clay minerals and feldspars are disappeared in ultra-fine grained layer. This implies that chemical process of dissolution - elements dissipation - SiO2 precipitation occurred associated with mechanical fracturing. Therefore nano spherules would be generated through mechano-chemical process during co-seismic slip. Dynamic shear strength drop by rapid slip experimentsare and formation of gelled materials are recently reported. Large differences of ultra-fine products between previous reports and our observations are existence of nano spherules and their crystallinity. If the nano- spherules are generated during seismic slip, dynamic weakening would be expected because mode of friction turns into rolling friction by huge amounts of equigranular and spherical grains. This may be alternative explanations for dynamic weakening. Quantitative process of dynamic fracturing will be discussed in our presentation.

  16. Surface slip associated with the 2014 South Napa, California earthquake measured on alinement arrays

    NASA Astrophysics Data System (ADS)

    Lienkaemper, J. J.; Brooks, B. A.; DeLong, S. B.; Domrose, C. J.; Rosa, C. M.

    2014-12-01

    The main rupture associated with the South Napa earthquake of Sept. 24, 2014 was ~15 km long from its epicenter (defined here as km 0, see figure below) to the surface rupture's north end (~km 15). Near km 10 a maximum of ~0.45 m dextral slip was most likely entirely coseismic, because it showed the same amount of slip at 12 days post-earthquake (d-PE) as it did at 1.5 d-PE. However, farther south (km~6) by 1-2 d-PE conspicuous growth of offsets on cultural features indicated high rates of afterslip (~10-20 cm/day) had occurred. Although afterslip is gradually slowing, it is expected to continue for many months or possibly years. To closely monitor this rapid afterslip, we installed four 70-140-m-long alinement arrays across the main rupture (labeled NLAR-NLOD on figure below), measuring slip to millimeter accuracy. A fifth array that spans a northeastern branch rupture has shown no afterslip. We have run early observations (to 26-d-PE) of afterslip (coupled with accumulated total slip as measured on adjacent offset cultural features) in the program AFTER (Boatwright et al., 1989). This analysis allows us to make preliminary estimates of initial (1 d-PE), final or total accumulated event slip, and coseismic estimates (i.e., projecting slip toward a ~0.5-1 s rise time). Thus far modeled slip on all four arrays indicates that final values of total (coseismic plus post-seismic) slip might be approaching the maximum coseismic slip as a limit (~0.4 ± 0.1 m). The final values of total surface slip may thus become more uniform along the fault over time as compared to modeled heterogeneous seismic slip at depth. The timing of the surface slip release differs strikingly from south to north along the 2014 rupture; AFTER models suggest that slip south of the location of maximum slip (km 0-10) appears to have been dominantly postseismic (~50-100%), whereas north of the maximum slip (km 10-15) slip was mainly coseismic (~50-100%). The current AFTER model predicts that as surface slip along the fault approaches final values of total slip associated with this earthquake (e.g., ?1000 d-PE), the respective contributions to the total event surface slip integrated along the entire fault will approach being 27% coseismic slip and 73% postseismic slip. . . .

  17. Slip and Dilation Tendency Analysis of the Patua Geothermal Area

    SciTech Connect

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = ? / ?n (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (?1-?n) / (?1-?3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency analysis for the Patua geothermal system was calculated based on faults mapped in the Hazen Quadrangle (Faulds et al., 2011). Patua lies near the margin between the Basin and Range province, which is characterized by west-northwest directed extension and the Walker Lane province, characterized by west-northwest directed dextral shear. As such, the Patua area likely has been affected by tectonic stress associated with either or both of stress regimes over geologic time. In order to characterize this stress variation we calculated slip tendency at Patua for both normal faulting and strike slip faulting stress regimes. Based on examination of regional and local stress data (as explained above) we applied at shmin direction of 105 to Patua. Whether the vertical stress (sv) magnitude is larger than ...

  18. A Simple Stick-Slip and Creep-Slip Model for Repeating Earthquakes and its Implication for Microearthquakes at Parkfield

    Microsoft Academic Search

    N. M. Beeler; D. L. Lockner; S. H. Hickman

    2001-01-01

    If repeating earthquakes are represented by circular ruptures, have con- stant stress drops, and experience no aseismic slip, then their recurrence times should vary with seismic moment as tM r ? 0 13 \\/ . In contrast, the observed variation for small, characteristic repeating earthquakes along a creeping segment of the San Andreas fault at Parkfield (Nadeau and Johnson, 1998)

  19. Compliant Joints For Robots

    NASA Technical Reports Server (NTRS)

    Kerley, James J., Jr.

    1990-01-01

    Compliant joints devised to accommodate misalignments of tools and/or workpieces with respect to robotic manipulators. Has characteristics and appearance of both universal-joint and cable-spring-type flexible shaft coupling. Compliance derived from elastic properties of short pieces of cable. Compliance of joint determined by lengths, distances between, relative orientations, thickness of strands, number of strands, material, amount of pretwist, and number of short pieces of cable. Worm-drive mechanism used to adjust lengths to vary compliance as needed during operation.

  20. Slow Earthquakes and The Mechanics of Slow Frictional Stick-Slip

    NASA Astrophysics Data System (ADS)

    Marone, Chris; Scuderi, Marco; Leeman, John; Saffer, Demian; Collettini, Cristiano; Johnson, Paul

    2015-04-01

    Slow earthquakes represent one mode of the spectrum of fault slip behaviors ranging from steady aseismic slip to normal earthquakes. Like normal earthquakes, slow earthquakes can occur repetitively, such that a fault fails in a form of stick-slip failure defined by interseismic strain accumulation and slow, quasidynamic slip. The mechanics of frictional stick-slip and seismogenic faulting appear to apply to slow earthquakes, however, the mechanisms that limit dynamic slip velocity, rupture propagation speed, and the scaling between moment and duration of slow earthquakes are poorly understood. Here, we describe laboratory experiments that explore the mechanics of repetitive, slow frictional stick-slip failure. We document the role of loading stiffness and friction constitutive behavior in dictating the properties of repetitive, frictional stick-slip. Our results show that a spectrum of dynamic and quasidynamic slip velocities can occur in stick-slip events depending on the relation between loading stiffness k and the rheologic critical stiffness kc given, in the context of rate and state friction, by the ratio of the friction rate parameter (b-a) divided by the critical friction distance Dc. Slow slip is favored by conditions for which k is ~ equal to kc, whereas normal, fast stick slip occurs when k/kc < 1. We explore the role of elastic coupling and spatially extended slip propagation by comparing slow slip results for shear in a layer driven by forcing blocks of varying stiffness. We evaluate our data in the framework of rate and state friction laws and focus on the frictional mechanics of slow stick-slip failure with special attention paid to the connections between quasidynamic failure and mechanisms of the brittle-ductile transition in fault rocks.

  1. Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie Bar, & Diagonal Brace Joint Detail; Chord, Tie Bar, & Crossbracing Joint Detail - Medora Bridge, Spanning East Fork of White River at State Route 235, Medora, Jackson County, IN

  2. Slip Accumulation During Normal Fault Growth, Asal Rift

    NASA Astrophysics Data System (ADS)

    Manighetti, I.; Gaudemer, Y.; Perrin, F.; Pinzuti, P.; Feuillet, N.

    2001-12-01

    We investigate the mechanisms of normal fault growth in Asal rift, one of the most recent and active of Afar. The faults offset ~100 ka-old volcanic surfaces, forming long, high (< 10 and 0.2 km) scarps, along which we previously studied the cumulative slip distributions (Manighetti et al., 2001). Some of these faults also cut lacustrine limestones deposited by the Asal lake before its retreat ~6 ka ago, forming smaller scarplets at the base of the cumulative scarps. Combining digital photographs and distance measurements, we measured the heights of such scarplets along five of the faults. Here, we present the results obtained on two of them, one large (A4) and one small (A21) (6 and 1.5 km-long, and 200 and 20 m-high cumulative scarps, respectively). Both faults slipped fast in the last 6 kyr, at a maximum rate higher on the larger fault (7.5+/-0.7 mm/yr versus 1.5+/-0.2 mm/yr on A21). If such maximum rates kept constant in time, we infer that A4 and A21 initiated 27+/-3 and 13+/-3 ka ago, respectively. As A4 slipped by at most 40 cm during the last 1978 seismic sequence, we deduce a recurrence time for similar crisis of 50-120 yr (depending on creep rate), much shorter than previously estimated. Comparing cumulative and 6 ka slip distributions show that, in the last 6 kyr, both faults accumulated vertical displacement without increasing in length. The envelop-shapes of their overall slip distributions remained unchanged, with maximum and minimum slip occurring in the same zones, and overall displacement decreasing almost linearly along the same, long portions of the faults. Growth mainly implied an increase of the maximum displacement (d) over fault length (l) ratio (r=d/l). At a more detailed level, the 6 ka slip profiles show first and second-order irregularities which match those previously detected in the cumulative profiles and interpreted to be connected fault segments. Results suggest that normal faults grow by alternating phases of slip accumulation and lateral propagation. During a first phase, a fault accumulates displacement without increasing in length, from a stage when r is minimum (rmin) to an ultimate stage when r reaches a maximum threshold (rmax; both values previously determined from data). As its length does not increase, the fault may produce characteristic earthquakes. When rmax is reached, the fault starts lengthening, hence propagating, so that r decreases possibly down to rmin. Then, the fault starts again accumulating displacement. The rmin and rmax values determined so far imply that, during its propagation phase, a fault is likely to increase its length by a factor of ~4. They also imply that A4 and A21 are both able to accumulate displacement without propagating for ~25 ka. This makes A21 being currently accumulating slip, whereas A4 is just starting propagating, as previously shown from other evidence. Ref : Manighetti et al., JGR, July 2001

  3. Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area

    SciTech Connect

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = ? / ?n (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (?1-?n) / (?1-?3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency for the Tuscarora geothermal field was calculated based on the faults mapped Tuscarora area (Dering, 2013). The Tuscarora area lies in the Basin and Range Province, as such we applied a normal faulting stress regime to the Tuscarora area faults, with a minimum horizontal stress direction oriented 115, based on inspection of local and regional stress determinations, as explained above. Under these stress conditions north-northeast striking, steeply dipping fault segments have the highest dilation tendency, while north-northeast striking 60° dipping fault segments have the highest tendency to slip. Tuscarora is defined by a left-step in a major north- to-north northeast striking, west-dipping range-bounding normal fault system. Faults within the broad step define an anticlinal accommodation zone...

  4. Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.

    1996-01-01

    Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The rise time and rupture propagation velocity depend on the choice of constitutive parameters. The second strength function is a natural log velocity-dependent form similar to constitutive laws that fit experimental rock friction data at lower velocities. Slip pulses also arise with this function. For a reasonable choice of constitutive parameters, slip pulses with this function do not propagate at speeds greater than the Raleighwave velocity. The calculated slip pulses are similar in many aspects to seismic observations of short rise time. In all cases of self-healing slip pulses, the residual stress increases with distance behind the trailing edge of the pulse so that the final stress drop is much less than the dynamic stress drop, in agreement with the model of Brune (1976) and some recent seismological observations of rupture.

  5. Joint fluid Gram stain

    MedlinePLUS

    Gram stain of joint fluid ... result means no bacteria are present on the Gram stain. Note: Normal value ranges may vary slightly ... Abnormal results mean bacteria were seen on the Gram stain. This may be a sign of a ...

  6. The Slumgullion Natural Laboratory for Observing Slip Phenomena

    NASA Astrophysics Data System (ADS)

    Gomberg, J. S.; Schulz, W. H.; Bodin, P.; Kean, J. W.; Wang, G.; Coe, J. A.; MacQueen, P.; Foster, K.; Creager, K.

    2009-12-01

    Many natural systems release stresses by failure and sliding across surfaces; examples include landslides, glaciers, crustal- and plate-scale faults. Observational advances continue to reveal diversity in the seismic signals associated with fault slip and how such stress relaxation can occur, even on a single fault system. A particularly rich example are the episodes of slow fault slip near major subduction and transform plate boundaries that manifest as geodetically observed aseismic deformation abetted by a family of seismic signals depleted in high-frequencies relative to those from earthquakes (named ‘episodic tremor and slip’ or ETS). While the driving forces and scales differ, there are striking parallels between some observations and models of ETS and of landslide behaviors; e.g. in both, postulated key controls include rate-dependent friction and strength modulated by pore-pressure changes, dilatancy during rapid shear, and subsequent consolidation. To explore common features and the underlying processes we are studying the Slumgullion landslide, an ideal natural laboratory for observing fault slip and associated seismic and aseismic phenomena. Unlike crustal- or plate-scale studies significant deformation can be measured within a single field season, because the Slumgullion moves at average rates of cm/day. Moreover, pore pressures, displacements, material properties, and environmental variables may be measured directly and continuously at several locations on the landslide (albeit not at the basal sliding surface). We have just completed a field experiment on the Slumgullion to test several hypotheses, particularly that slip along the basal surface and side-bounding faults occurs with comparable richness of aseismic and seismic modes as crustal- and plate-scale boundaries. To do so from August 18-26, 2009 we continuously monitored the displacement-field using a robotic electronic displacement meter and the seismic radiation with 88 vertical-component seismographs [see Bodin et al., companion abstract]. Although we have only begun examining the data thus far, the seismic data contain an abundance of network-wide coherent signals with an amazing variety of characteristics. Significant unsteady movement in the displacement field is evident in the geodetic data, as well as fluctuations in the pore-pressures and relevant environmental parameters. Schulz et al. (companion abstract) presents initial landslide observations. We will form and present implications for understanding the likely mechanisms of failure and slip within natural systems.

  7. Dual Megathrust Slip Behaviors of the 2014 Iquique Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Meng, L.; Huang, H.; Burgmann, R.; Ampuero, J. P.; Strader, A. E.

    2014-12-01

    The transition between seismic rupture and aseismic creep is of central interest to better understand the mechanics of subduction processes. A M 8.2 earthquake occurred on April 1st, 2014 in the Iquique seismic gap of Northern Chile. This event was preceded by a 2-week-long foreshock sequence including a M 6.7 earthquake. Repeating earthquakes are found among the foreshock sequence that migrated towards the mainshock area, suggesting a large scale slow-slip event on the megathrust preceding the mainshock. The variations of the recurrence time of repeating earthquakes highlights the diverse seismic and aseismic slip behaviors on different megathrust segments. The repeaters that were active only before the mainshock recurred more often and were distributed in areas of substantial coseismic slip, while other repeaters occurred both before and after the mainshock in the area complementary to the mainshock rupture. The spatial and temporal distribution of the repeating earthquakes illustrate the essential role of propagating aseismic slip in leading up to the mainshock and aftershock activities. Various finite fault models indicate that the coseismic slip generally occurred down-dip from the foreshock activity and the mainshock hypocenter. Source imaging by teleseismic back-projection indicates an initial down-dip propagation stage followed by a rupture-expansion stage. In the first stage, the finite fault models show slow initiation with low amplitude moment rate at low frequency (< 0.1 Hz), while back-projection shows a steady initiation at high frequency (> 0.5 Hz). This indicates frequency-dependent manifestations of seismic radiation in the low-stress foreshock region. In the second stage, the high-frequency rupture remains within an area of low gravity anomaly, suggesting possible upper-crustal structures that promote high-frequency generation. Back-projection also shows an episode of reverse rupture propagation which suggests a delayed failure of asperities in the foreshock area. Our results highlight the complexity of the interactions between large-scale aseismic slow-slip and dynamic ruptures of megathrust earthquakes.

  8. Slip resistance of industrial floor surfaces: development of an elastomer suited to in-situ measurement.

    PubMed

    Leclercq, S; Saulnier, H

    2001-01-01

    Slips contribute to 12% of occupational accidents. A slip resistant floor is a mean to prevent slipping accidents occurring in workshops. Floor slip resistance is often evaluated by measuring a friction index, proportional to the force opposing slipping of a reference elastomer on the floor surface under test. When implementing a portable appliance, slip resistance measurements carried out on lubricated floors were not stabilized. The authors advanced the hypothesis of oil impregnating the elastomer. A new elastomer suited to in-situ measurement has been developed to achieve stable measuring conditions. This study highlights the fact that the nature and characteristics of a reference elastomer must be specified when slip resistance measurements are carried out. PMID:11276267

  9. Noninfectious joint disease in cattle.

    PubMed

    Nichols, Sylvain; Lardé, Hélène

    2014-03-01

    Osteochondrosis causes variable degrees of joint effusion and lameness. Arthroscopic debridement of the lesions provides the best long-term outcome. Articular fracture or joint instability following collateral ligament rupture causes severe joint effusion and lameness. Internal fixation combined with external coaptation is the treatment of choice. Degenerative joint disease in young animals has a guarded prognosis. Arthroscopy combined with medical therapy may slow down the disease process. Degenerative joint disease involving the distal interphalangeal joint has a good prognosis following joint resection. PMID:24534666

  10. Wheel slip control of ABS using ER valve pressure modulator

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Bok; Cho, Myung-Soo; Kim, Yong-Il; Choi, Young-Tai; Wereley, Norman M.

    2004-07-01

    This paper presents a wheel slip control via sliding mode controller for a new anti-lock brake system (ABS) of a passenger vehicle using electrorheological (ER) valve pressure modulator. The principal design parameters of the ER valves and hydraulic booster are appropriately determined by considering braking pressure variation during ABS operation. An electrically controllable pressure modulator using the ER valves is then constructed and its governing equations are derived. Subsequently, the pressure control performance of the new pressure modulator is experimentally evaluated. The governing equations of motion for a quarter car wheel model are derived and the sliding mode controller is formulated for wheel slip control. Hardware in the loop simulation (HILS) for braking performance evaluation is undertaken in order to demonstrate the effectiveness of the proposed ABS associated with the ER valve pressure modulator.

  11. A Novel Algorithm for Cycle Slip Detection and Repair

    NASA Astrophysics Data System (ADS)

    Sezen, U.; Arikan, F.

    2012-04-01

    Accurate and reliable estimation of ionospheric parameters are very important for correct functioning of communication, navigation and positioning satellite systems. In recent years, dual-frequency GPS receivers are widely used for estimation of Total Electron Content (TEC), which is defined as the line integral of the electron density along a ray path. Since both electron density and TEC are functions of solar, geomagnetic, gravitational and seismic activity, any disturbance along the ray path can be detected using GPS receiver observables. It is observed that, with the development of recent sophisticated receivers, disruptions due to the receiver antenna, hardware or outside obstructions are minimized. Most of the observed sudden disturbances are signal phase lock losses due to ionosphere. These sudden phase shifts are named as cycle slips and if not corrected, they may lead to positioning errors or incorrect TEC estimates. There are many methods in the literature that deal with cycle slips and their repairs, yet these methods are not matured to detect all kinds of cycle slips. Most algorithms require double differencing, and/or complicated Kalman Filters, Wavelet transforms, Neural Network models, and integration of external INS systems. In this study, we propose a fast and efficient algorithm for identifying the cycle slips on individual observables, classifying them for future investigations and finally repairing them for more accurate and reliable TEC estimates. The algorithm traces the pseudorange and phase observables and computes the geometry free combinations of L4 and P4. The sudden disturbances on L1, L2, P1, C1 and P2 are classified and noted for further use. Most of the cases, the disruptions are on phase observables, yet for a few occasions, a sudden disturbance is also observed on pseudorange observables. The algorithm, then, checks the epoch section where P4 exists continually. When a disruption on L1 or L2 occurs, it becomes evident on L4. When P4 and L4 sections are compared with each other, with the use of a common base, the sudden disruptions up to three epochs can be corrected using second order interpolation. For disruptions that continue for more than three epochs are considered to be separate sections and treated within that epoch section. Any cycle slip occuring within an epoch section is corrected efficiently using thresholds based on cumulative mean of the derivatives. With the efficient repair of cycle slips, Slant TEC (STEC) values can be reliably estimated, and by categorizing the cycle slips with respect to the observables, satellite and epoch, the reason of disturbance can be identified. The cycle slip detection and repair algorithm is incorporated into the web version of IONOLAB-TEC and they can be reached presently from the site www.ionolab.org. This study is supported by TUBITAK EEEAG under Grant No: 109E055.

  12. Solute effect on basal and prismatic slip systems of Mg

    NASA Astrophysics Data System (ADS)

    Moitra, Amitava; Kim, Seong-Gon; Horstemeyer, M. F.

    2014-11-01

    In an effort to design novel magnesium (Mg) alloys with high ductility, we present a first principles data based on the Density Functional Theory (DFT). The DFT was employed to calculate the generalized stacking fault energy curves, which can be used in the generalized Peierls–Nabarro (PN) model to study the energetics of basal slip and prismatic slip in Mg with and without solutes to calculate continuum scale dislocation core widths, stacking fault widths and Peierls stresses. The generalized stacking fault energy curves for pure Mg agreed well with other DFT calculations. Solute effects on these curves were calculated for nine alloying elements, namely Al, Ca, Ce, Gd, Li, Si, Sn, Zn and Zr, which allowed the strength and ductility to be qualitatively estimated based on the basal dislocation properties. Based on our multiscale methodology, a suggestion has been made to improve Mg formability.

  13. Cytoplasmic streaming in plant cells: the role of wall slip

    PubMed Central

    Wolff, K.; Marenduzzo, D.; Cates, M. E.

    2012-01-01

    We present a computer simulation study, via lattice Boltzmann simulations, of a microscopic model for cytoplasmic streaming in algal cells such as those of Chara corallina. We modelled myosin motors tracking along actin lanes as spheres undergoing directed motion along fixed lines. The sphere dimension takes into account the fact that motors drag vesicles or other organelles, and, unlike previous work, we model the boundary close to which the motors move as walls with a finite slip layer. By using realistic parameter values for actin lane and myosin density, as well as for endoplasmic and vacuole viscosity and the slip layer close to the wall, we find that this simplified view, which does not rely on any coupling between motors, cytoplasm and vacuole other than that provided by viscous Stokes flow, is enough to account for the observed magnitude of streaming velocities in intracellular fluid in living plant cells. PMID:22337633

  14. Combined effects of compressibility and slip in flows of a HerschelBulkley fluid Yiolanda Damianou a

    E-print Network

    Georgiou, Georgios

    Combined effects of compressibility and slip in flows of a Herschel­Bulkley fluid Yiolanda Damianou­Bulkley fluid Poiseuille flow Navier slip Pressure-dependent slip Compressibility a b s t r a c t In this work, the combined effects of compressibility and slip in Poiseuille flows of Herschel­Bulkley flu- ids

  15. 1 Coseismic slip on the southern Cascadia megathrust 2 implied by tsunami deposits in an Oregon lake

    E-print Network

    Goldfinger, Chris

    rupture scenarios: slip partitioned to a splay fault; slip distributed symmetrically on the 14 megathrust, that solves nonlinear shallow-water wave 16 equations on unstructured grids. Our simulations of the 1700 >260 years. Simple slip budgets constrained by 23 tsunami simulations allow an average of 5.2 m of slip

  16. Microscale disk-induced gas displacement with and without slip

    Microsoft Academic Search

    Danny Blanchard; Phil Ligrani

    2007-01-01

    Displacements of gas flows, both with and without slip, are described for rotation-induced flows in a C-shaped fluid chamber passage formed between a rotating disk and a stationary surface, with a height h of 13.3 µm. Included are accommodation coefficients for the stationary smooth wall, smooth disk surface, medium rough disk surface rough disk surface. Flow rate and pressure rise

  17. Slip and twinning dislocations in sapphire (?-Al2O3)

    Microsoft Academic Search

    A. H. Heuer; K. P. D. Lagerlöf; J. Castaing

    1998-01-01

    The 1\\/3 (1010) partial dislocation plays a crucial role in the plastic deformation of sapphire (?-Al2O3). During deformation at high temperatures, basal slip (1\\/3(1120) (0001)) has the lowest critical resolved shear stress; 1\\/3 (1120) perfect dislocations undergo dissociation (which is probably restricted to the dislocation core) to 1\\/3(1010) and 1\\/3 (0110) half-partial dislocations. These partials glide on an electrically neutral

  18. Why are slip lengths so large in carbon nanotubes?

    Microsoft Academic Search

    Tim G. Myers

    2011-01-01

    A possible explanation for the enhanced flow in carbon nanotubes is given using a mathematical model that includes a depletion\\u000a layer with reduced viscosity near the wall. In the limit of large tubes the model predicts no noticeable enhancement. For\\u000a smaller tubes the model predicts enhancement that increases as the radius decreases. An analogy between the reduced viscosity\\u000a and slip-length

  19. Slip Modes of Hexagonal-Close-Packed Metals

    Microsoft Academic Search

    M. H. Yoo; C. T. Wei

    1967-01-01

    The effective shear moduli, dislocation line energies, dislocation widths, and relative ease of gliding have been calculated for the (0001) [112¯0], (11¯00) [112¯0], (11¯01) [112¯0], (112¯2) [112¯3¯], and (hk.0) [0001] slip systems in each of the hexagonal close-packed metals Cd, Zn, Mg, Co, Zr, Ti, and Be by applying anisotropic elasticity theory of dislocations. Except for the case of Be,

  20. Composite slip table of dissimilar materials for damping longitudinal modes

    DOEpatents

    Gregory, Danny L. (Albuquerque, NM); Priddy, Tommy G. (Albuquerque, NM); Smallwood, David O. (Albuquerque, NM); Woodall, Tommy D. (Albuquerque, NM)

    1991-01-01

    A vibration slip table for use in a vibration testing apparatus. The table s comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes.

  1. Inversion for slip distribution for the 2012 Costa Rica earthquake

    NASA Astrophysics Data System (ADS)

    McCormack, K. A.; Hesse, M. A.; Stadler, G.

    2014-12-01

    On 5 September 2012, a major megathrust earthquake (Mw=7.6) ruptured the plate interface beneath the Nicoya Peninsula, Costa Rica. This event was centered 12 km offshore of the central Nicoya coast, at a depth of 18 km. The maximum slip exceeded 2 meters, and the rupture spread outward along the plate interface to encompass 3000 km2 of the Nicoya seismogenic zone. More than 1700 aftershocks were recorded within the first 5 days. These aftershocks outlined two distinct rupture patches; one centered on the central coast and the other beneath the southern tip of the peninsula. We formulate a Bayesian inverse problem to infer the coseismic slip on the fault plane based on instantaneous surface displacements and changes in well heads in order to image the remaining "locked" patch that has been inferred previously. We compute the maximum a posteriori (MAP) estimate of the posterior slip distribution on the fault, and use a local Gaussian approximation around the MAP point to characterize the uncertainty. The elastic deformation is computed using a finite element method that allows for the spatial variation of elastic properties that has been observed in the crust overlying the seismogenic zone. We solve the optimization problem using gradients obtained from adjoints. The linearity of the inverse problem allows for the efficient solution of the optimal experimental design problem for the placement of the GPS stations to monitor the remaining locked patch. In the future, the results obtained here will provide the initial condition for a time-dependent poroelastic model for fault slip and fluid migration due to overpressure caused by a megathrust earthquake. This will provide constraints on the crustal permeability structure in a tectonically active region.

  2. Stokes’ Second Problem for a Micropolar Fluid with Slip

    PubMed Central

    Florea, Olivia Ana; Ro?ca, Ileana Constan?a

    2015-01-01

    In this paper is presented the model of an incompressible micropolar fluid flow with slip using the initial and boundary conditions when the wall velocity is considered depending on the frequency of the vibration. Regarding the boundary conditions of the velocity at the wall, we remark that there is a discontinuity of the velocity at the fluid-wall interface. The solutions for velocity and microrotation with the given conditions are obtained using the method of numerical inversion of Laplace transform. PMID:26161780

  3. Aqueous slip casting of transparent yttrium aluminum garnet (YAG) ceramics

    Microsoft Academic Search

    Kwadwo A. Appiagyei; Gary L. Messing; John Q. Dumm

    2008-01-01

    Transparent YAG ceramics were prepared by slip casting an aqueous dispersed mixture of commercial Al2O3 and Y2O3 powders. The powders were co-dispersed with poly(acrylic acid) and citric acid. Polyethylene glycol of 0.5wt.% (PEG 4000) and 0.5wt.% tetraethyl orthosilicate were added as binder and a sintering aid, respectively. Dried samples were vacuum sintered at 1800°C for 16h. In general, YAG ceramics

  4. Self-organized criticality in a stick-slip process

    Microsoft Academic Search

    Hans Jacob S. Feder; Jens Feder

    1991-01-01

    The force required to pull sandpaper across a carpet fluctuates. Slips (sudden drops of magnitude M of the force) are observed to have a probability N(M>m)~m-b with b~=0.8. The power spectrum of force fluctuations has a low-frequency 1\\/f behavior. Thus our system reaches a self-organized critical state with fractal scaling in both the spatial and the time domain. We introduce

  5. Seismic responses to fluid pressure perturbations in a slipping fault

    NASA Astrophysics Data System (ADS)

    Derode, Benoit; Guglielmi, Yves; De Barros, Louis; Cappa, Frédéric

    2015-05-01

    Seismicity induced by fluid injection in a natural fault is investigated in situ in the near field of the source. We present synchronous seismic and hydromechanical measurements directly recorded in the decametric injection zone. The three main types of seismic events were recorded during injection and shut-in: high-amplitude and short duration seismic events (SE) (i.e., microearthquakes), low to constant amplitude and 5 to 17 s long tremor-like signals (TLS), and long period events (LP) with a narrow-frequency band content. Seismicity first initiates with a sequence of SE and TLS, when pressure is high (~3.5 MPa), slip is activated on the fault, which experiences a twentyfold increase of permeability. Then LP events appear to be associated to fluid leakage in the fault caused by dilation during slip. During shut-in, residual pressures as low as 0.6 MPa still trigger SE events. We show that the initial TLS sequence triggers when a progressive transition occurs from rupture controlled by effective stress variations close to the injection source to a large friction weakening-dominated slip on the fault. We conclude that the combination of these different seismic signal types may be a proxy to monitor fault instability associated to fluid pressure perturbations.

  6. Stick-Slip Motion of DNA in a Solid Nanopore

    NASA Astrophysics Data System (ADS)

    Luan, Binquan; Martyna, Glenn

    2009-03-01

    Nanopore technology is a potential solution for the low-cost and high-throughput DNA sequencing. Till now, in a typical experiment DNA driven by an electric field translocates through a nanopore too fast to be detected at a single-base resolution. The recently proposed DNA transistor (Appl. Phys. Lett. 91, 153103 (2007)) holds the promise to trap DNA inside a nanopore and translocate single-stranded DNA (ssDNA) at a single-base resolution. Using extensive all-atom molecular dynamics simulations, we modeled the process of ssDNA's translocation through the DNA transistor when ssDNA is pulled by an optical tweezer. We found a stick-slip type of motions of DNA when both the stiffness of an optical tweezer and the pulling velocity are below critical values. This irregular motion of DNA is quantitatively characterized using the Tomlinson model. In a typical slip event, ssDNA advances one nucleotide spacing, while in a stick state the base of DNA can be conveniently measured. The duration of a stick state depends on the strength of a trapping field in the DNA transistor, the stiffness of an optical tweezer and the pulling velocity. Therefore, the controlled stick-slip motion of DNA is ideal for DNA sequencing methods using a solid nanopore.

  7. Distribution of strike-slip faults on Europa

    NASA Astrophysics Data System (ADS)

    Hoppa, Gregory; Greenberg, Richard; Tufts, B. Randall; Geissler, Paul; Phillips, Cynthia; Milazzo, Moses

    2000-09-01

    Study of four different regions on Europa imaged by the Galileo spacecraft during its first 15 orbits has revealed 117 strike-slip faults. Europa appears to form preferentially right-lateral faults in the southern hemisphere and left-lateral faults in the northern hemisphere. This observation is consistent with a model where diurnal tides due to orbital eccentricity drive strike-slip motion through a process of ``walking,'' in which faults open and close out of phase with alternating right-and left-lateral shear. Lineaments that record both left-and right-lateral motion (e.g., Agave Linea) may record the accommodation of compression in nearby chaotic zones. Nearly all identified strike-slip faults were associated with double ridges or bands, and few were detected along ridgeless cracks. Thus the depth of cracks without ridges does not appear to have penetrated to the low-viscosity decoupling layer, required for diurnal displacement, but cracks that have developed ridges do extend down to such a level. This result supports a model for ridge formation that requires cracks to penetrate to a decoupling layer, such as a liquid water ocean.

  8. Wave propagation across non-linear rock joints based on time-domain recursive method

    NASA Astrophysics Data System (ADS)

    Li, J. C.

    2013-05-01

    Studying wave propagation across joints is crucial in geophysics, mining and underground construction. Limited analyses are available for oblique incidence across non-linear joints. In this paper, the time-domain recursive method (TDRM) proposed by Li et al. is extended to analyse wave propagation across a set of non-linear joints. The Barton-Bandis model (B-B model) and the Coulomb-slip model are adopted to describe the non-linear normal and shear properties of the joints, respectively. With the displacement discontinuity model and the time shifting function, the wave propagation equation is established for incident longitudinal-(P-) or transverse-(S-)wave across the joints with arbitrary impinging angles. Comparison between the results from the TDRM and the existing methods is carried out for two specific cases to verify the derived wave propagation equation. The effects of some parameters, such as the incident angle, the joint spacing, the amplitude of incidence and the joint maximum allowable normal closure, on wave propagation are discussed.

  9. A method for the joint inversion of geodetic and seismic waveform data using ABIC: application to the 1997 Manyi, Tibet, earthquake

    NASA Astrophysics Data System (ADS)

    Funning, Gareth J.; Fukahata, Yukitoshi; Yagi, Yuji; Parsons, Barry

    2014-03-01

    Geodetic imaging data and seismic waveform data have complementary strengths when considering the modelling of earthquakes. The former, particularly modern space geodetic techniques such as Interferometric Synthetic Aperture Radar (InSAR), permit high spatial density of observation and thus fine resolution of the spatial pattern of fault slip; the latter provide precise and accurate timing information, and thus the ability to resolve how that fault slip varies over time. In order to harness these complementary strengths, we propose a method through which the two data types can be combined in a joint inverse model for the evolution of slip on a specified fault geometry. We present here a derivation of Akaike's Bayesian Information Criterion (ABIC) for the joint inversion of multiple data sets that explicitly deals with the problem of objectively estimating the relative weighting between data sets, as well as the optimal influence of model smoothness constraints in space and time. We demonstrate our ABIC inversion scheme by inverting InSAR displacements and teleseismic waveform data for the 1997 Manyi, Tibet, earthquake. We test, using a simplified fault geometry, three cases-InSAR data inverted alone, vertical component teleseismic broad-band waveform data inverted alone and a joint inversion of both data sets. The InSAR-only model and seismic-only model differ significantly in the distribution of slip on the fault plane that they predict. The joint-inversion model, however, has not only a similar distribution of slip and fit to the InSAR data in the InSAR-only model, suggesting that those data provide the stronger control on the pattern of slip, but is also able to fit the seismic data at a minimal degradation of fit when compared with the seismic-only model. The rupture history of the preferred, joint-inversion model, indicates bilateral rupture for the first 20 s of the earthquake, followed by a further 25 s of westward unilateral rupture afterwards, with slip peaking at 7 m in the upper 6 km of the fault. This joint-inversion approach is thus shown to be a viable method for the study of large shallow continental earthquakes, and may be of particular benefit in cases where near-field seismic observations are not available.

  10. Workers' experience of slipping in U.S. limited-service restaurants.

    PubMed

    Verma, Santosh K; Chang, Wen-Ruey; Courtney, Theodore K; Lombardi, David A; Huang, Yueng-Hsiang; Brennan, Melanye J; Mittleman, Murray A; Perry, Melissa J

    2010-09-01

    The leading cause of injuries among restaurant workers is same-level falls, a significant proportion of which result from slipping. This study examines the experience of limited-service restaurant workers with slipping, their use of slip-resistant shoes, and their floor-cleaning practices. A total of 475 workers from 36 limited-service restaurants in six U.S. states participated in a 12-week prospective cohort study on slipping in the workplace. At baseline, participants completed a survey that gathered information about their demographics, perceptions of floor slipperiness, use of slip-resistant shoes, floor cleaning practices, and number of slips experienced in the previous 4 weeks. During the subsequent 12 weeks, participants reported their slip experience weekly. Restaurant managers reported kitchen floor cleaning protocols and shoe policies. The overall rate of slipping during the 12 weeks of the prospective study was 0.44 slips per 40 work hours. The mean of the individual rate of slipping varied among the restaurants from 0.02 to 2.49 slips per 40 work hours, a rate ratio of more than 100 among the restaurants with the highest and the lowest rate of slipping. Such a large variation, which is unlikely due to chance alone (p < 0.05), suggests that some restaurants are better able to control slipping than others. The highest numbers of slips were reported in the sink and fryer areas, which were also identified by restaurant workers as being the most slippery. Liquid and grease were reported as floor contaminants in over 70% of the slips. In restaurants where slip-resistant shoes were provided by the employer, 91% of participants wore them; whereas if they were neither provided nor encouraged, only 53.5% wore them (p < 0.01). Use of enzyme-based floor cleaners was widespread (25/36). In these restaurants, however, 62% of the participants who were responsible for cleaning floors reported using hot/warm water, thus violating the manufacturer's cold water floor cleaning protocol. These findings suggest that focused prevention efforts based on practices from restaurants with low rates of slipping could decrease slipping hazards. PMID:20552500

  11. The Relationship Between Coseismic Slip and Postseismic Creep

    NASA Astrophysics Data System (ADS)

    Hussain, E.; Wright, T. J.; Houseman, G. A.; Walters, R. J.; Hooper, A. J.; Bekaert, D. P.

    2014-12-01

    Shallow aseismic creep has been observed on many strike-slip faults around the world. The initiation process for shallow creep remains unclear, and no clear explanation exists for why creep persists for years/decades after some earthquakes while after others it decays completely within months. Many earthquakes exhibit a shallow coseismic slip deficit. We hypothesise that shallow creep can begin after such events to 'catch up' with the slip deficit relative to deeper sections of the fault. We test this hypothesis with persistent scatterer InSAR analysis of 3 descending and 2 ascending Envisat tracks that together span a region covering the 1999 Izmit and Duzce ruptures in Turkey. Our data covers an 8 year time window between 2003 - 2010. A section of the Izmit rupture was previously shown to be undergoing shallow creep. But the spatial and temporal nature of this creep remains unclear. We use a small baseline processing strategy using the StaMPS software, which allows for checking of unwrapping errors by summing the residuals around closed interferometric loops. We make an addition to the code to detect and fix unwrapping errors. This is done by automatically detecting and fixing pixels that are unwrapped correctly in an initial run. The procedure is iterated until unwrapping errors are corrected. By combining our InSAR results with existing GPS measurements we obtained a map of horizontal and vertical surface displacements over time. From this we calculated the variation in creep rates along the earthquake ruptures. We show that shallow creep at an average rate of 10 mm/yr is limited to the Izmit rupture and does not extend laterally to the Duzce segment. We use elastic dislocation models to determine the creep distribution with depth and compare with the coseismic slip observed in the Izmit earthquake. We find the creep rate is highest in a region of shallow coseismic slip deficit. The creep rate exponentially decays with time after the earthquake to a steady rate. We model this temporal behaviour using rate and state friction theory and determine variations in frictional properties within the creeping region.

  12. Improved ceramic slip casting technique. [application to aircraft model fabrication

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (inventor); Vasquez, Peter (inventor)

    1993-01-01

    A primary concern in modern fluid dynamics research is the experimental verification of computational aerothermodynamic codes. This research requires high precision and detail in the test model employed. Ceramic materials are used for these models because of their low heat conductivity and their survivability at high temperatures. To fabricate such models, slip casting techniques were developed to provide net-form, precision casting capability for high-purity ceramic materials in aqueous solutions. In previous slip casting techniques, block, or flask molds made of plaster-of-paris were used to draw liquid from the slip material. Upon setting, parts were removed from the flask mold and cured in a kiln at high temperatures. Casting detail was usually limited with this technique -- detailed parts were frequently damaged upon separation from the flask mold, as the molded parts are extremely delicate in the uncured state, and the flask mold is inflexible. Ceramic surfaces were also marred by 'parting lines' caused by mold separation. This adversely affected the aerodynamic surface quality of the model as well. (Parting lines are invariably necessary on or near the leading edges of wings, nosetips, and fins for mold separation. These areas are also critical for flow boundary layer control.) Parting agents used in the casting process also affected surface quality. These agents eventually soaked into the mold, the model, or flaked off when releasing the case model. Different materials were tried, such as oils, paraffin, and even an algae. The algae released best, but some of it remained on the model and imparted an uneven texture and discoloration on the model surface when cured. According to the present invention, a wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell mold of the calcium sulfate-bonded investment material. The shell mold is cooled to room temperature, and a ceramic slip is poured therein. After a ceramic shell of desired thickness has set up in the shell mold, excess ceramic slip is poured out. While still wet, the shell mold is peeled from the ceramic shell to expose any delicate or detailed parts, after which the ceramic shell is cured to provide a complete, detailed, precision ceramic article without parting lines.

  13. Effective slip in pressure-driven flow past super-hydrophobic stripes

    E-print Network

    Belyaev, Aleksey V

    2009-01-01

    Super-hydrophobic array of grooves containing trapped gas (stripes), have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused on idealized cases of stick-perfect slip stripes, with limited guidance. Here, we analyze the experimentally relevant situation of a pressure-driven flow past striped slip-stick surfaces with arbitrary local slip at the gas sectors. We derive analytical formulas for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that can be used for any surface slip fraction (validated by numerical calculations). By representing eigenvalues of the slip length-tensor, they allow us to obtain the effective slip for any orientation of stripes with respect to the mean flow. Our results imply that flow past stripes is controlled by the ratio of the local slip length to texture size. In case of a large (compared to the texture period) slip at the gas areas, surface anisotropy leads to a tensorial effective slip...

  14. Temporal Changes in the Required Shoe-Floor Friction when Walking following an Induced Slip

    PubMed Central

    Beringer, Danielle N.; Nussbaum, Maury A.; Madigan, Michael L.

    2014-01-01

    Biomechanical aspects of slips and falls have been widely studied to facilitate fall prevention strategies. Prior studies have shown changes in gait after an induced slipping event. As such, most researchers only slip participants one time to avoid such changes that would otherwise reduce the external validity of experimental results. The ability to slip participants more than once, after allowing gait to return to a natural baseline, would improve the experimental efficiency of such studies. Therefore, the goal of this study was to characterize the temporal changes in required shoe-floor friction when walking following an induced slip. Two experiments were completed, and each employed a different potential strategy to promote the return of gait to a natural baseline after slipping. In the first experiment, extended time away from the laboratory was used to promote the return of gait to baseline. We measured required coefficient-of-friction among 36 young adult male participants over four sessions. The first three sessions provided measurements during baseline (i.e., natural gait) both prior to slipping and immediately after slipping. The fourth session provided a measurement 1–12 weeks after slipping. In the second experiment, an extensive number of walking trials was used to promote the return of gait to baseline. We measured required coefficient-of-friction among 10 young adult male participants in a single session. Measurements were collected during 10 baseline walking trials, immediately after slipping, and during 50–55 additional trials. In both experiments, required coefficient-of-friction decreased 12–16% immediately after a single slip, increased toward baseline levels over subsequent weeks/walking trials, but remained statistically different from baseline at the end of the experiments. Based on these results, experiments involving slipping participants multiple times may not have a high level of external validity, and researchers are encouraged to continue to limit experimental protocols to a single induced slip per participant. PMID:24789299

  15. Jet impingement and the hydraulic jump on horizontal surfaces with anisotropic slip

    NASA Astrophysics Data System (ADS)

    Prince, Joseph F.; Maynes, Daniel; Crockett, Julie

    2014-04-01

    This paper presents an analysis that describes the dynamics of laminar liquid jet impingement on horizontal surfaces with anisotropic slip. Due to slip at the surface and the anisotropy of its magnitude, the overall behavior departs notably from classical results. For the scenario considered the slip length varies as a function of the azimuthal coordinate and describes superhydrophobic surfaces micropatterned with alternating ribs and cavities. The thin film dynamics are modeled by a radial momentum analysis for a given jet Reynolds number and specified slip length and the influence of slip on the entire flow field is significant. In an average sense the thin film dynamics exhibit similarities to behavior that exists for a surface with isotropic slip. However, there are also important deviations that are a direct result of the azimuthally varying slip and these become more pronounced at higher Reynolds numbers and at greater slip lengths. The analysis also allows determination of the azimuthally varying radial location of the hydraulic jump that forms due to an imposed downstream depth. Departure from the no slip case and from the scenario of isotropic slip is characterized over a range of jet Reynolds numbers and realistic slip length values. The results show that for all cases the hydraulic jump is elliptical, with eccentricity increasing as the Reynolds number or slip length increases, or as the downstream depth decreases. The radial location of the hydraulic jump is greatest in the direction of greatest slip (parallel to the microribs), while it is a minimum in the direction transverse to the rib/cavity structures. The model results for the hydraulic jump radial position are compared to experimental measurements with good agreement.

  16. New Joint Sealants. Criteria, Design and Materials.

    ERIC Educational Resources Information Center

    Building Research Inst., Inc., Washington, DC.

    Contents include--(1) sealing concrete joints, (2) sealing glass and metal joints, (3) metal and glass joint sealants from a fabricator's viewpoint, (4) a theory of adhesion for joint sealants, (5) geometry of simple joint seals under strain, (6) joint sealant specifications from a manufacturer's viewpoint, (7) joint sealant requirements from an…

  17. Temporal Feasibility of Rapid Joint Inversions in Response to Tsunamis Triggered by Megathrust Earthquakes

    NASA Astrophysics Data System (ADS)

    Williamson, A.; Newman, A. V.

    2014-12-01

    Joint inversions of sub-areal surface deformation and tsunami waves generated by seafloor ground motions, while still in their infancy, have the opportunity for realistic representations of megathrust earthquake slip responsible, which occurs primarily offshore. Such joint inversions, including Gusman, et al. [JGR, 2010] and Wei et al. [PAGEOPH, 2014], highlight fault slip unobservable with on land measurements alone. Careful detection of possible slip patterns can affect how nearby communities prepare for future events, therefore their discovery is important for hazard mitigation. Joint inversions could also prove invaluable during a large even through a rapid inversion of real time data. This study looks at the availability and accessibility of land-based GPS and deep-ocean pressure sensor data for rapid join inversions, and the latency between such solutions and both local and global tsunami wave arrivals. We consider GPS rather than other ground-based deformation techniques because of its ability to provide rapid and continuous translations of the ground surface. For tsunami observations, we focus on deep-ocean pressure sensors such as those used in DART systems, because of similarly rapid and continues data availability. Similarly tsunami waves traveling through the deep-ocean have negligible non-linear components, making them ideal for inversion methods. We create a source event in a zone with an elevated seismic risk and then track tsunami travel times to the coast and the nearest deep-ocean pressure sensors to determine a temporal limit to warnings that can be issued to nearby regions. By assessing this latency, focus can be given to areas where an inversion of this type has the potential to improve warning information. This study also identifies regions that lack necessary on and offshore instrumentation to warn coastal communities at risk for tsunamigenic earthquakes. By assessing the feasibility of joint inversions, it becomes easier to move forward with future studies focusing on regions that would see the largest benefit in real-time hazard mitigation.

  18. Joint for deployable structures

    NASA Technical Reports Server (NTRS)

    Craighead, N. D., II; Preliasco, R. J.; Hult, T. D. (inventors)

    1985-01-01

    A joint is described for connecting a pair of beams to pivot them between positions in alignment or beside one another, which is of light weight and which operates in a controlled manner. The joint includes a pair of fittings and at least one center link having opposite ends pivotally connected to opposite fittings and having axes that pass through centerplates of the fittings. A control link having opposite ends pivotally connected to the different fittings controls their relative orientations, and a toggle assemly holds the fittings in the deployed configuration wherein they are aligned. The fittings have stops that lie on one side of the centerplane opposite the toggle assembly.

  19. STUDY ON THE EFFECTIVENESS OF EARTHQUAKE-RESISTANT JOINT AGAINST SEISMIC DISPLACEMENT IN UNDERGROUND STRUCTURE

    NASA Astrophysics Data System (ADS)

    Otsuka, Hisanori; Aibe, Takeaki; Soejima, Sumireko

    In the current seismic design of underground structure, only earthquake shaking is considered and the influence of fault displacement is not considered. However, since linear underground structure such as tunnels have a possibility to be constructed across faults, they have a probability to get severe damage due to the fault displacement. In this study, Soil-underground structure-seismic fault model is analyzed by 3D finite element analysis considering slip and exfoliation between structure and the effect of fault displacement on the underground structure are evaluated. Further more the applicability of the earthquake resistant joints used for underground structure as countermeasure of ground excitations to fault displacements are studied by the numerical analysis, and it is clarified that the more increasing the number of joints and the decreasing of the space of joints introduce the more reducing of cross sectional forces.

  20. The evolution of slip surface roughness during earthquake propagation in carbonate faults

    NASA Astrophysics Data System (ADS)

    Zhu, B.; De Paola, N.; Llewellin, E. W.; Holdsworth, R.

    2014-12-01

    Slip surface roughness is understood to control the dynamics of earthquake propagation. Quantifying the micro- and nano-scale roughness of slip surfaces can give insight into the grain-scale processes controlling the strength of faults during earthquake propagation. Friction experiments were performed on fine-grained calcite gouges, at speed 1 ms-1, normal stress 18 MPa, displacements 0.009-1.46 m, and room temperature and humidity. Results show a two stage-evolution (S1-2) of the fault strength, with an initial increase up to peak value 0.82 (S1), followed by a sudden decrease to a low, steady-state value 0.18 (S2). Samples retrieved at the end of S1 show the development of a cohesive slip zone (SZ), made of micron-scale, angular clasts formed by brittle fracturing and cataclasis. The SZ of samples deformed up to S2, is composed of nanograin aggregates which exhibit polygonal grain boundaries indicating high temperature grain boundary sliding creep deformation. In both cases, the SZ is bounded by a sharply defined slip surface. The 3-D geometry of seven experimental slip surfaces (40?m×40?m) has been reconstructed by digital processing of sets of 1800 images of SZ cross sections acquired at 20 nm intervals perpendicular to the slip direction, using a slicing (Focussed Ion Beam) and viewing (Field Emission Scanning Electron Microscope) technique. Spectrum power density analyses show that nano- and micron-scale slip surface roughness is anisotropic for both S1 and S2 slip surfaces. At the nano- and micron-scale, root mean square values decrease with length for S1 slip surfaces, but only slightly for S2 surfaces, and are anisotropic in the slip-normal and slip-parallel directions. The anisotropy is reduced at the nano-scale, although S2 slip surfaces are still smoother parallel to slip than normal to slip. Hurst exponents vary through scales, and are anisotropic in the directions parallel and normal to slip. Variable Hurst exponents indicate that slip surface roughness is scale-dependent with anisotropic, not self-affine behaviour at the micro/nano-scale, in contrast to the self-affine behaviour inferred at the mm to km scales. Dynamic weakening and creep deformation, observed during S2, coincide with an evolution towards less anisotropic and scale-dependent slip surface roughness at the nanoscale.

  1. Sensitivity of the stability of a waste emplacement drift to variation in assumed rock joint parameters in welded tuff

    SciTech Connect

    Christianson, M.

    1989-04-01

    This report presents the results of a numerical analysis to determine the effects of variation of rock joint parameters on stability of waste disposal rooms for vertical emplacement. Conditions and parameters used were taken from the Nevada Nuclear Waste Storage Investigation (NNWSI) Project Site Characterization Plan Conceptual Design report (MacDougall et al., 1987). Mechanical results are presented which illustrate the predicted distribution of stress, joint slip, and room deformations for times of initial excavation and after 50 years heating. 82 refs., 93 figs.

  2. Joints in a Cornstarch Analog

    NSDL National Science Digital Library

    Juliet Crider

    Joints are very important to problems in applied geology (fluid flow, slope stability), but three-dimensional exposures of simple joint sets are not readily accessible from my campus. I developed this exercise based on the experiments of Miller (2001) to give students hands-on practice describing and interpreting joints. For the exercise, I prepare a cornstarch-water mixture a few days in advance and pour it into plastic petri dishes. I add a "flaw" to each dish (typically a small pebble). As the cornstarch dries, vertical joints develop. In class, each group of 3-4 students is provided a petri dish of desiccated cornstarch. Students are asked to draw a map of the joints, paying particular attention to intersection angles. (The joints curve to intersect at 90 degrees.) They determine relative ages of the joints using abutting relationships. (Typically 3-6 generations of joints.) Students next dissect the sample and describe the surface textures of the larger joints and the location of the flaw. The cornstarch produces beautiful plumose structure (hackles). Students then interpret the joint propagation direction from the surface textures, and note the origin of the joint. (Typically, a first- or second-generation joint initiates at the flaw.) Students discuss the role of flaws in the initiation of joints in their groups.

  3. Relation between surface slip topography and stress corrosion cracking in Ti-8 wt % Al

    NASA Technical Reports Server (NTRS)

    Boyd, J. D.; Hoagland, R. G.

    1974-01-01

    The deformation behavior of Ti-8 wt % Al has been investigated in an inert environment (air), and an aggressive environment (salt water). Details of surface slip geometry were examined by high resolution surface replicas at various stages of deformation in both environments. Specimens aged to contain a fine dispersion of Ti3Al precipitates failed by subcritical crack growth in salt water, whereas specimens in the single phase condition showed no effects of environment on the yield or fracture characteristics. The Ti3Al precipitates produce little change in strength level or slip character compared to the single phase alloy, and there is no evidence of any effects of environment on the character of surface slip. Rather, the presence of trenches along slip bands on the surface of aged specimens suggest that the specific effect of the Ti3Al precipitates is to render the surface slip steps chemically active relative to the surrounding matrix by slip induced dissolution of the particles.

  4. Initiation time of near-infrared laser-induced slip on the surface of silicon wafers

    SciTech Connect

    Choi, Sungho [Graduate School of Mechanical Engineering, Hanyang University, Seoul 133–791 (Korea, Republic of); Jhang, Kyung-Young, E-mail: kyjhang@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133–791 (Korea, Republic of)

    2014-06-23

    We have determined the initiation time of laser-induced slip on a silicon wafer surface subjected to a near-infrared continuous-wave laser by numerical simulations and experiments. First, numerical analysis was performed based on the heat transfer and thermoelasticity model to calculate the resolved shear stress and the temperature-dependent yield stress. Slip initiation time was predicted by finding the time at which the resolved shear stress reached the yield stress. Experimentally, the slip initiation time was measured by using a laser scattering technique that collects scattered light from the silicon wafer surface and detects strong scattering when the surface slip is initiated. The surface morphology of the silicon wafer surface after laser irradiation was also observed using an optical microscope to confirm the occurrence of slip. The measured slip initiation times agreed well with the numerical predictions.

  5. A new approach to the determination of the critical slip surfaces of slopes

    NASA Astrophysics Data System (ADS)

    Li, Liang; Cheng, Y. M.; Chu, Xue-song

    2013-03-01

    A new method for the determination of the critical slip surfaces of slopes is proposed in this paper. In this paper, the original critical slip field method is extended in terms of the total residual moment, values of residual work as well as the unbalanced thrust force at the exit point for a given non-circular slip surface. The most critical slip surface with the maximum representative value for a prescribed factor of safety will be optimized and located using the harmony search algorithm. The prescribed factor of safety is modified with certain tiny interval in order to find the critical slip surface where the maximum representative value is zero. The aforementioned approach to the location of the critical slip surface is greatly different from the traditional limit equilibrium procedure. Three typical soil slopes are evaluated by use of the proposed method, and the comparisons with the classical approaches have illustrated the applicability of the proposed method.

  6. Variable rates of late Quaternary strike slip on the San Jacinto fault zone, southern California.

    USGS Publications Warehouse

    Sharp, R.V.

    1981-01-01

    3 strike slip displacements of strata with known approximate ages have been measured at 2 locations on the San Jacinto fault zone. Minimum horizontal offset between 5.7 and 8.6km in no more than 0.73Myr NE of Anza indicates 8-12 mm/yr average slip rate since late Pleistocene time. Horizontal slip of 1.7m has been calculated for the youngest sediment of Lake Cahuilla since its deposition 271- 510 yr BP. The corresponding slip rate is 2.8-5.0 mm/yr. Right lateral offset of 10.9m measured on a buried stream channel older than 5060 yr BP but younger than 6820 yr BP yields average slip rates for the intermediate time periods, 400 to 6000 yr BP of 1-2 mm/yr. The rates of slip suggest a relatively quiescent period from about 4000 BC to about 1600 AD.-from Author

  7. Coseismic and Postseismic slip distribution of the 2007 Solomon Islands Earthquake deduced from A Bayesian Inversion

    NASA Astrophysics Data System (ADS)

    Chen, T.; Gong, X.

    2011-12-01

    In inversion of geodetic data for distribution of fault slip minimizing the first or second order derivatives of slip across fault plane is generally employed to smooth slips of neighboring patches.Smoothing parameter is subjective selected to determine the relative weight placed on fitting data versus smoothing the slip distribution.We use the Fully Bayesian Inversion method(Fukuda,2008)to simultaneously estimate the slip distribution and smoothing parameter objectively in a Bayesian framework. The distributed slips,the posterior probability density function and the smoothing parameter is formulated with Bayes' theorem and sampled with a Markov chain Monte Carlo method. Here We will apply this method to Coseismic and Postseismic displacement data from the 2007 Solomon Islands Earthquake and compare the results of this method with generally favored method.

  8. Clad metal joint closure

    SciTech Connect

    Siebert, O.W.

    1985-04-09

    A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.

  9. CARTILAGE, BONES, AND JOINTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cartilage is a special type of connective tissue that is of extreme importance in embryonic development, serving as the model upon which true bone is later formed. Cartilage also persists in adult animals, primarily as articular cartilage which cushions the interface between adjacent bones or joint...

  10. Joint publication: Department of

    E-print Network

    Watson, Craig A.

    century. The first law to protect consumers was passed in 1906, and Charles Dadant is credited with getJoint publication: Florida Department of Agriculture & Consumer Services University of Florida Florida Department of Agriculture & Consumer Services 1911 SW 34 Street PO Box 147100 Gainesville, FL

  11. Dolphin Skeleton (Gliding Joint)

    NSDL National Science Digital Library

    Ketan Patel (California State University, Fullerton; )

    2007-07-14

    The dolphin is built to be sleek. Its body is made of almost entirely backbone (a gliding joint) which makes it very flexible under water. The ribs protect the inner organs of the dolphin and the tail beats from side to side, thrusting the animal forward.

  12. Joint Honours AFRICAN STUDIES

    E-print Network

    Miall, Chris

    : The Joint Honours African Studies degree programme at Birmingham is broad, combining arts and social Office - Retail management - Aid work with Save the Children - Probation work - Welfare rights worker - Computer programmer - NGO work in Kurdistan - Work with adults who have learning disabilities - Research

  13. Slip resistance of the shoe-floor interface under biomechanically-relevant conditions

    Microsoft Academic Search

    MARK S. REDFERN; BOPAYA BIDANDA

    1994-01-01

    Slip resistance measurements are used by industry, shoe\\/floor manufacturers, and the legal profession as a criterion for determining slip potentials of various environments. Whilst static coefficients of friction (COF) of a shoe-floor interface have been used traditionally, dynamic COF(DCOF) measures have been shown to be more relevant to the biomechanics of slips and falls. Recently, new devices have become available

  14. The 2002 Denali Fault Earthquake, Alaska: A Large Magnitude, Slip-Partitioned Event

    Microsoft Academic Search

    Donna Eberhart-Phillips; Peter J. Haeussler; Jeffrey T. Freymueller; Arthur D. Frankel; Charles M. Rubin; Patricia Craw; Natalia A. Ratchkovski; Greg Anderson; Gary A. Carver; Anthony J. Crone; Timothy E. Dawson; Hilary Fletcher; Roger Hansen; Edwin L. Harp; Ruth A. Harris; David P. Hill; Sigrún Hreinsdóttir; Randall W. Jibson; Lucile M. Jones; Robert Kayen; David K. Keefer; Christopher F. Larsen; Seth C. Moran; Stephen F. Personius; George Plafker; Brian Sherrod; Kerry Sieh; Nicholas Sitar; Wesley K. Wallace

    2003-01-01

    The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali

  15. Real-Time Stick-Slip and Vibration Detection for 8 ½\\

    Microsoft Academic Search

    Junichi Sugiura; Steve Jones

    In an extended-reach and horizontal well drilling environment, stick-slip becomes increasingly problematic with smaller-diameter and longer drillstrings. Surface detection of the bottom-hole assembly stick-slip and vibration becomes ever more difficult. A Real-time Stick-slip and Vibration Detection (RSVD) system was incorporated into a new 8 ½- inch-hole-size Rotary Steerable System (RSS), to increase drilling efficiency in deep wells and to protect

  16. TWO TYPES OF SLIP-INDUCED FALLS AMONG COMMUNITY DWELLING OLDER ADULTS

    PubMed Central

    Yang, Feng; Espy, Debbie; Bhatt, Tanvi; Pai, Yi-Chung

    2012-01-01

    Little is known about the landing behavior of the trailing (recovery) foot and ensuing types of falls following a forward slip in walking. The purposes of this study were to 1) determine if community-dwelling older adults experienced bilateral slips at the same rate as had been previously observed for young adults during over-ground walking; 2) determine if fall rate in older adults was dependent on slip type (unilateral vs. bilateral); and 3) identify differences in spatiotemporal variables of the trailing leg step between unilateral and bilateral slips. One-hundred-seventy-four participants experienced an unannounced, unrehearsed slip while walking on a 7-m walkway. Each trial was monitored with a motion capture system and bilateral ground reaction force plates. Although the experimental design, developed with original data from a young adult population, favored bilateral slips, more older adults (35%) than anticipated (10% previously observed in young, p<0.001) displayed a unilateral slip. The probability of fall was equal in the two types of slips. Eighty-two people recovered from the slip, while the remaining 92 (53%) fell. These 92 were classified into two exclusive categories based on the heel distance at the time of fall arrest using cluster analysis: those which resembled a fall into a "splits" position (n=47) or a feet-forward fall (n=45). All (100%) unilateral slips led to splits falls, as expected. Yet, not all bilateral slips (only 83%) resulted in feet-forward falls. A longer forward recovery step with a prolonged step time led to both feet slipping, nearly together, hence a feet-forward fall. PMID:22338614

  17. Two types of slip-induced falls among community dwelling older adults.

    PubMed

    Yang, Feng; Espy, Debbie; Bhatt, Tanvi; Pai, Yi-Chung

    2012-04-30

    Little is known about the landing behavior of the trailing (recovery) foot and ensuing types of falls following a forward slip in walking. The purposes of this study were to (1) determine if community-dwelling older adults experienced bilateral slips at the same rate as had been previously observed for young adults during over-ground walking; (2) determine if fall rate in older adults was dependent on slip type (unilateral vs. bilateral); and (3) identify differences in spatiotemporal variables of the trailing leg step between unilateral and bilateral slips. One-hundred-seventy-four participants experienced an unannounced, unrehearsed slip while walking on a 7-m walkway. Each trial was monitored with a motion capture system and bilateral ground reaction force plates. Although the experimental design, developed with original data from a young adult population, favored bilateral slips, more older adults (35%) than anticipated (10% previously observed in young, p<0.001) displayed a unilateral slip. The probability of fall was equal in the two types of slips. Eighty-two people recovered from the slip, while the remaining 92 (53%) fell. These 92 were classified into two exclusive categories based on the heel distance at the time of fall arrest using cluster analysis: those which resembled a fall into a "splits" position (n=47) or a feet-forward fall (n=45). All (100%) unilateral slips led to splits falls, as expected. Yet, not all bilateral slips (only 83%) resulted in feet-forward falls. A longer forward recovery step with a prolonged step time led to both feet slipping, nearly together, hence a feet-forward fall. PMID:22338614

  18. Slip-flow irreversibility of dissipative kinetic and internal energy exchange in microchannels

    Microsoft Academic Search

    E O B Ogedengbe; G F Naterer; M A Rosen

    2006-01-01

    The mechanisms of near-wall velocity slip and their effects on energy conversion of fluid motion in microchannels are investigated. Unlike large-scale channels with no-slip boundary conditions, this paper predicts how streamwise temperature gradients and transverse velocity gradients contribute to velocity slip during intermolecular interactions near a microchannel wall. A numerical formulation is developed with a mass-weighted convection scheme (called NISUS;

  19. Slip distribution of the 2003 Tokachi-oki earthquake estimated from tsunami waveform inversion

    Microsoft Academic Search

    Yuichiro Tanioka; Kenji Hirata; Ryota Hino; Toshihiko Kanazawa

    2004-01-01

    The slip distribution of the 2003 Tokachi-oki earthquake is estimated from the 11 tsunami waveforms recorded at 9 tide gauges in the southern Hokkaido and eastern Tohoku coasts and two ocean bottom tsunami-meters (pressure gauges) off Kamaishi, Tohoku. The largest slip of 4.3 m is estimated on the subfault located off Hiroo. A large slip of 2.1 m is also

  20. Strike-slip faulting of ridged plains near Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Schultz, R. A.

    1989-10-01

    This paper identifies and documents several well-preserved examples of Martian strike-slip faults and examines their relationships to wrinkle-ridges. The strike-slip faulting predates or overlaps periods of wrinkle-ridge growth southeast of Valles Marineris, and some wrinkle ridges may have nucleated and grown as a result of strike-slip displacements along the echelon fault arrays. Lateral displacements of several km inferred along these arrays may be related to tectonism in Tharsis.

  1. Robust ? -synthesis controllers for suppressing stick-slip induced vibrations in oil well drill strings

    Microsoft Academic Search

    M. Karkoub; M. Zribi; L. Elchaar; L. Lamont

    2010-01-01

    Stick-slip friction is a major cause of drill-string failure. This paper addresses the problem of suppressing stick-slip induced\\u000a oscillations in oil well drill strings using a control design technique known as ?-synthesis. This technique allows for the inclusion of modeling errors in the control design process in terms of uncertainty\\u000a weights. The dynamic model of the drill string with stick-slip

  2. An investigation of stick-slip friction on the contouring accuracy of cnc machine tools

    Microsoft Academic Search

    Y. S. Tarng; H. E. Cheng

    1995-01-01

    Stick-slip friction has a great influence on the contouring accuracy of CNC machine tools. In this paper, a nonlinear model is used to simulate and analyze dynamic behaviors of stick-slip friction on the contouring accuracy of CNC machine tools. A simple control strategy is then developed to tune the control loop gain for reducing the contouring error due to stick-slip

  3. Target slip tracking using gain-scheduling for antilock braking systems

    Microsoft Academic Search

    Yong Liul; Jing Sun

    1995-01-01

    In this paper, a gain-scheduling scheme is proposed for optimal target slip tracking of an antilock braking system. The study is based on the fact that for certain road surface condition, the tire force characterization, i.e. the force-slip curve, is indeed varying with respect to different vehicle forward speed. The optimal slip at which the braking force achieves its maximum

  4. On first cycle slip time of phase-locked loops in cascade

    NASA Technical Reports Server (NTRS)

    Yuen, J. H.

    1974-01-01

    Precise measurement and spacecraft tracking are obtained by using phase-locked loops in cascade in two-way communications links. Statistics on cycle slip time are of vital importance in system planning and design. This paper presents: (1) results of a computer simulation study of the mean time to first cycle slip of cascade phase-locked loops preceded by bandpass limiters, and (2) the determination of probability distributions of cycle slip. Numerical results are obtained for a typical coherent communication system.

  5. River Captures and Erosional Disequilibrium Along Strike-slip Faults

    NASA Astrophysics Data System (ADS)

    Brocard, G. Y.; Fayon, A. K.; Perg, L. A.; Paola, C.; Teyssier, C.; Whitney, D. L.; Mota, M.; Moran-Ical, S.

    2005-12-01

    River captures are internal instabilities of erosion systems and are inherently promoted by strike-slip faulting. A capture event can generate a wave of incision that propagates from the capture site upstream and/or downstream, resulting in an increased bulk erosion rate around the capture site. Thus, under steady boundary conditions, drainage diversions trigger pulses of erosion, sediment production, rock exhumation and isostatic rebound. Therefore, a significant part of the erosion in oblique tectonics can be achieved in a state of significant departure from short-term dynamic equilibrium. The frequency, intensity, and duration of these events set the timescale over which their integrated effects can be regarded as the expression of a long-term dynamic equilibrium. We are investigating the effects of a large river capture on the oblique collision between the North American and Caribbean plates in Guatemala. Several thousands of kilometers of strike-slip displacement have been accommodated along this boundary during the Tertiary. The deformation is now concentrated mostly along the E-W Motagua strike-slip fault. Oblique tectonics is discernable within a 50 km wide topographic belt, north of this fault (Sierra de las Minas - Sierra de Chuacus range). On the northern flank of this range, deformation includes 130 km offset across the Polochic strike-slip fault, documented by both geological structures and drainage patterns. Numerous elbows and dry valleys show the progressive transformation of the initial transverse (S-N) drainage crossing the fault into a transverse-parallel (E-W) system that developed during increasing displacement along the fault. The drainage reorganization operates by river lengthening, captures, and avulsions. One of the latest capture sites is surrounded by a large (110x30 km) zone of deeply (1500 m) dissected landscape that coincides with the captured catchment. This zone sharply contrasts with the surrounding areas where large fragments of a very subdued topography are preserved on the highlands. The capture has been interpreted as the diversion of the former headwaters of a westward flowing river located south of the fault (Rio Selegua) into a northward flowing river located north of the fault (Rio Chixoy), based on drainage pattern and preserved conglomerates. The capture event, the dissection of the landscape, and the uplift of the summit paleosurface are closely related, and likely Miocene in age. Newly discovered conglomerates confirm that the captured basin was drained by the Selegua River before being drained into the Chixoy River. Other newly discovered paleovalleys and conglomerates further document the expansion of the dissected captured watershed at the expense of surrounding catchments. Since the capture event, both the captured stream paleovalley and the subdued topography have been displaced by large normal faults, many of them striking parallel to the Polochic strike-slip fault. Recent faulted sediments on the Polochic Fault trace also display a significant vertical component of slip. The inception of this tectonic activity after the abandonment of the paleovalleys suggests that the faults may have accommodated the isostatic uplift that followed unloading of the captured drainage basin by erosion.

  6. Experimental Modeling of Dynamic Shallow Dip-Slip Faulting

    NASA Astrophysics Data System (ADS)

    Uenishi, K.

    2010-12-01

    In our earlier study (AGU 2005, SSJ 2005, JPGU 2006), using a finite difference technique, we have conducted some numerical simulations related to the source dynamics of shallow dip-slip earthquakes, and suggested the possibility of the existence of corner waves, i.e., shear waves that carry concentrated kinematic energy and generate extremely strong particle motions on the hanging wall of a nonvertical fault. In the numerical models, a dip-slip fault is located in a two-dimensional, monolithic linear elastic half space, and the fault plane dips either vertically or 45 degrees. We have investigated the seismic wave field radiated by crack-like rupture of this straight fault. If the fault rupture, initiated at depth, arrests just below or reaches the free surface, four Rayleigh-type pulses are generated: two propagating along the free surface into the opposite directions to the far field, the other two moving back along the ruptured fault surface (interface) downwards into depth. These downward interface pulses may largely control the stopping phase of the dynamic rupture, and in the case the fault plane is inclined, on the hanging wall the interface pulse and the outward-moving Rayleigh surface pulse interact with each other and the corner wave is induced. On the footwall, the ground motion is dominated simply by the weaker Rayleigh pulse propagating along the free surface because of much smaller interaction between this Rayleigh and the interface pulse. The generation of the downward interface pulses and corner wave may play a crucial role in understanding the effects of the geometrical asymmetry on the strong motion induced by shallow dip-slip faulting, but it has not been well recognized so far, partly because those waves are not expected for a fault that is located and ruptures only at depth. However, the seismological recordings of the 1999 Chi-Chi, Taiwan, the 2004 Niigata-ken Chuetsu, Japan, earthquakes as well as a more recent one in Iwate-Miyagi Inland, Japan in 2008, for example, seem to support the need for careful mechanical consideration. In this contribution, utilizing two-dimensional dynamic photoelasticity in conjunction with high speed digital cinematography, we try to perform "fully controlled" laboratory experiments of dip-slip faulting and observe the propagation of interface pulses and corner waves mentioned above. A birefringent material containing a (model) dip-slip fault plane is prepared, and rupture is initiated in that material using an Nd:YAG laser system, and the evolution of time-dependent isochromatic fringe patterns (contours of maximum in-plane shear stress) associated with the dynamic process of shallow dip-slip faulting is recorded. Use of Nd:YAG laser pulses, instead of ignition of explosives, for rupture initiation may enhance the safety of laboratory fracture experiments and enable us to evaluate the energy entering the material (and hence the energy balance in the system) more precisely, possibly in a more controlled way.

  7. Seismic Slip on an Oblique Detachment Fault at Low Angles

    NASA Astrophysics Data System (ADS)

    Janecke, S. U.; Steely, A. N.; Evans, J. P.

    2008-12-01

    Pseudotachylytes are one of the few accepted indicators of seismic slip along ancient faults. Low-angle normal faults have produced few large earthquakes in historic times and low-angle normal faults (detachment faults) are typically severely misoriented relative to a vertical maximum compressive stress. As a result many geoscientists question whether low-angle normal faults produce earthquakes at low angles. Relationships in southern California show that a major low-angle normal-oblique fault slipped at low angles and produced large earthquakes. The exhumed Late Cenozoic West Salton detachment fault preserves spectacular fault- related pseudotachylytes along its fault plane and injected into its hanging wall and footwall. Composite pseudotachylyte zones are up to 1.25 m thick and persists over lateral distances of at least 10's of meters. Pseudotachylyte is common in most thin sections of damaged fault rocks with more than 20% (by volume) of cataclasite. We recognized the presence of original melt using numerous criteria: abundant spherulites in thin sections, injection structures at both the thin-section and outcrop scale, black aphanitic textures, quenched vein margins, variations in microcrystallite textures and/or size with respect to the vein margin, and glassy textures in hand sample. Multiple earthquakes are inferred to produce the layered "stratigraphy" in some exposures of pseudotachylytes. We infer that the West Salton detachment fault formed and slipped at low angles because it nearly perfectly reactivates a Cretaceous ductile thrust system at the half km scale and dips between 10 and 45 degrees. The about 30 degree NNE dip of the detachment fault on the north side of Yaqui Ridge is likely steeper than its dip during detachment slip because there is local steepening on the flanks of the Yaqui Ridge antiform in a contractional stepover of a crosscutting Quaternary San Felipe dextral fault zone. These relationships indicate a low dip on the detachment fault when the detachment was active, when it produced voluminous pseudotachylyte during eartquakes, and when the supradetachment basin above it received a large volume of sediment eroded from the pseudotachylyte-bearing parts of the damage zone. To interpret the pseudotachylyte as the product of slip across a detachment when it was dipping at least 45 degrees requires a sequence of events that is so unlikely that we reject it. There must have been seismic slip at low dip angles across the West Salton detachment fault. Our conclusion agrees with prior studies by John and Axen in the Chemehuevi and Whipple metamorphic core complex and increases the published catalogue of detachment faults that sport pseudotachylytes. These data document that low-angle normal faults are seismogenic, and that conditions that allow pseudotachylytes to form may occur at shallow levels in the crust.

  8. Joint Institute Marine and Atmospheric

    E-print Network

    Hawai'i at Manoa, University of

    Joint Institute for Marine and Atmospheric Research NATIONALOCEA NIC AND ATMOSPHERIC ADMINISTRATION Contribution 00-328 #12;ii This research is funded by Cooperative Agreement Number NA67RJ0154 between the Joint

  9. Comparison of Three Different Slip Meters under Various Contaminated Conditions

    PubMed Central

    2012-01-01

    Objectives To challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results. Methods Four common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics. Results The contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and Ra, while the rest did not show statistical significance with surface roughness parameters (Ra, Rz). The English XL only showed statistical significance (p < 0.01) between slip index and contaminants. The static coefficient of friction obtained with the BOT-3000 showed good consistency and repeatability (CV < 0.1) as compared to the results for the BPT (CV > 0.2) and English XL (CV < 0.2). Conclusion It is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve. PMID:22953227

  10. Interchange Slip-Running Reconnection and Sweeping SEP-Beams

    NASA Technical Reports Server (NTRS)

    Masson, S.; Aulanier, G.; Pariat, E.; Klein, K.-L.

    2011-01-01

    We present a new model to explain how particles, accelerated at a reconnection site that is not magnetically connected to the Earth, could eventually propagate along the well-connected open flux tube. Our model is based on the results of a low-beta resistive magnetohydrodynamics simulation of a three-dimensional line-tied and initially current-free bipole, that is embedded in a non-uniform open potential field. The topology of this configuration is that of an asymmetric coronal null-point, with a closed fan surface and an open outer spine. When driven by slow photospheric shearing motions, field lines, initially fully anchored below the fan dome, reconnect at the null point, and jump to the open magnetic domain. This is the standard interchange mode as sketched and calculated in 2D. The key result in 3D is that, reconnected open field lines located in the vicinity of the outer spine, keep reconnecting continuously, across an open quasi-separatrix layer, as previously identified for non-open-null-point reconnection. The apparent slipping motion of these field lines leads to form an extended narrow magnetic flux tube at high altitude. Because of the slip-running reconnection, we conjecture that if energetic particles would be travelling through, or be accelerated inside, the diffusion region, they would be successively injected along continuously reconnecting field lines that are connected farther and farther from the spine. At the scale of the full Sun, owing to the super-radial expansion of field lines below 3 solar radius, such energetic particles could easily be injected in field lines slipping over significant distances, and could eventually reach the distant flux tube that is well-connected to the Earth.

  11. Pericollisional strike-slip basins in western Cordillera, Canada

    SciTech Connect

    Eisbacher, G.H.

    1984-04-01

    The late Mesozoic-Paleogene evolution of the Canadian Cordillera was dominated by accretion of elongate crustal blocks against the North American craton. Geologic and paleomagnetic evidence suggest that these exotic terranes dispersed from volcanic arcs and oceanic platforms and approached North America along anastomosing right-lateral faults with great cumulative displacement. Obduction of oceanic allochthons was followed by transpressive thickening and regional metamorphism of the cratonic margin in the mid-Jurassic. Strike-slip motion and emplacement of plutonic rocks continued near relict sutures and reactivated deep faults. Sedimentary basins related to strike-slip faults formed by elongation of accreted terranes (''Stikinia'' and ''Wrangellia'') and by shear within the deformed cratonic margin zone (''Rocky Mountain Trench''). Subsidence is reflected by northwest-southeast stretching along pull-apart structures, and by massive influx of turbidites from incipient collision zones and relict are relief. It was interrupted and outlived by rotation of blocks, folding of basin sediments, and vigorous progradation of deltaic-fluvial clastics from rising collision belts. Transition from predominant transtension to prevailing transpression is diachronous from basin to basin. Near the Stikine-Wrangellia collision zone (Bowser basin), it occurred in the Late Jurassic; along the Stikine-Wrangellia border it occurred in the mid to Late Cretaceous. Only small nonmarine basins developed in the Rocky Mountain Trench system, which, in its southern-most part, was closed completely during Paleogene thrust faulting. The strike-slip basins of the western Canadian Cordillera were subject to high regional heat flow and also suffered from widespread intrusion of paleogene granitoids. Therefore, they are generally poor oil and gas prospects.

  12. Slip transition and dislocation structures in off-stoichiometric NiAl single crystals

    SciTech Connect

    Srinivasan, R.; Savage, M.F.; Mills, M.J. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Daw, M.S. [Clemson Univ., SC (United States). Dept. of Physics and Astronomy; Noebe, R.D. [NASA Lewis Research Center, Cleveland, OH (United States)

    1997-12-31

    Compression tests have been performed on hard-oriented Ni-44Al single crystals for several temperatures and strain levels. There is a slip transition from a<111> type slip to non-a<111> type slip which corresponds with the observation of yield points. Transmission electron microscopy studies provide evidence for decomposition of a<111> dislocations into a <101> and a<010> dislocations near the knee of the yield strength curve. The mechanism of this slip transition and the nature of the dislocation processes both below and above the knee are described.

  13. The 2002 Denali fault earthquake, Alaska: a large magnitude, slip-partitioned event.

    PubMed

    Eberhart-Phillips, Donna; Haeussler, Peter J; Freymueller, Jeffrey T; Frankel, Arthur D; Rubin, Charles M; Craw, Patricia; Ratchkovski, Natalia A; Anderson, Greg; Carver, Gary A; Crone, Anthony J; Dawson, Timothy E; Fletcher, Hilary; Hansen, Roger; Harp, Edwin L; Harris, Ruth A; Hill, David P; Hreinsdóttir, Sigrun; Jibson, Randall W; Jones, Lucile M; Kayen, Robert; Keefer, David K; Larsen, Christopher F; Moran, Seth C; Personius, Stephen F; Plafker, George; Sherrod, Brian; Sieh, Kerry; Sitar, Nicholas; Wallace, Wesley K

    2003-05-16

    The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity. PMID:12750512

  14. Flow past superhydrophobic surfaces with cosine variation in local slip length

    E-print Network

    Asmolov, Evgeny S; Harting, Jens; Vinogradova, Olga I

    2012-01-01

    Anisotropic super-hydrophobic surfaces have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused mostly on cases of super-hydrophobic stripes. Here, we analyze a relevant situation of cosine variation of the local slip length. We derive approximate formulae for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that are in good agreement with the exact numerical solution and lattice-Bolzmann simulations for any surface slip fraction. The cosine texture can provide a very large effective (forward) slip, but it was found to be less efficient in generating a transverse flow as compared to super-hydrophobic stripes.

  15. Molecular origin and dynamic behavior of slip in sheared polymer films.

    PubMed

    Priezjev, Nikolai V; Troian, Sandra M

    2004-01-01

    The behavior of the slip length in thin polymer films subject to planar shear is investigated using molecular dynamics simulations. At low shear rates, the slip length extracted from the velocity profiles correlates well with that computed from a Green-Kubo analysis. Beyond chain lengths of about N=10, the molecular weight dependence of the slip length is dominated strongly by the bulk viscosity. The dynamical response of the slip length with increasing shear rate is well captured by a power law up to a critical value where the momentum transfer between wall and fluid reaches its maximum. PMID:14754025

  16. Influence of boundary slip effect on thermal environment in thermo-chemical non-equilibrium flow

    NASA Astrophysics Data System (ADS)

    Miao, Wenbo; Zhang, Liang; Li, Junhong; Cheng, Xiaoli

    2014-12-01

    A kind of new hypersonic vehicle makes long-time flight in transitional flow regime where boundary slip effect caused by low gas density will have an important influence on the thermal environment around the vehicles. Numerical studies on the boundary slip effect as hypersonic vehicles fly in high Mach number has been carried out. The method for solving non-equilibrium flows considering slip boundary, surface catalysis and chemical reactions has been built up, and been validated by comparing the thermal environment results with STS-2 flight test data. The mechanism and rules of impact on surface heat flux by different boundary slip level (Knudsen number from 0.01 to 0.05) has been investigated in typical hypersonic flow conditions. The results show that the influence mechanisms of boundary slip effect are different on component diffusion heat flux and convective heat flux; slip boundary increases the near wall temperature which diminish the convective heat; whereas enhances the near wall gas diffusion heat because of the internal energy's growing. Component diffusion heat flux takes a smaller portion of the total heat flux, so the slip boundary reduces the total wall heat flux. As Knudsen number goes up, the degree of rarefaction increases, the influences of slip boundary on convective and component diffusion heat flux are both enhanced, total heat flux grows by a small margin, and boundary slip effect is more distinct.

  17. Cellular Pressure-Actuated Joint

    NASA Technical Reports Server (NTRS)

    McGuire, John R.

    2003-01-01

    A modification of a pressure-actuated joint has been proposed to improve its pressure actuation in such a manner as to reduce the potential for leakage of the pressurizing fluid. The specific joint for which the modification is proposed is a field joint in a reusable solid-fuel rocket motor (RSRM), in which the pressurizing fluid is a mixture of hot combustion gases. The proposed modification could also be applicable to other pressure-actuated joints of similar configuration.

  18. Dynamic slip velocity correlation using non-spherical particles

    E-print Network

    Pecore, Douglas Wilkin

    1990-01-01

    RECOMMENDATIONS NOMENCLATURE REFERENCES APPENDIX A . 1 2 6 11 13 15 15 25 31 31 36 42 43 45 47 APPENDIX B . Page 57 113 LIST OF FIGURES FIGURE 1: DRAG COEFFICIENT VS. PARTICLE REYNOLDS NUMBER FOR VARIOUS SHAPED PARTICLES FIGURE 2...: C VS. N?~ FOR DIFFERENT SPHERICITIES USING THE EXPERIMENTAL CORRELATION FIGURE 15 Q VS N~p THE FINAL CORRELATION FOR USE IN ESTIMATING SLIP VELOCITY FIGURE 16: FLUID RHEOLOGY CURVE FOR 1. 0 LB/BBL. HEC IN CARTESIAN COORDINATES FIGURE 17: FLUID...

  19. Determination of the of rate cross slip of screw dislocations

    PubMed

    Vegge; Rasmussen; Leffers; Pedersen; Jacobsen

    2000-10-30

    The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy and the effective attempt frequency can therefore be extracted from the simulations. The transition state energy for the annihilation process is calculated by identifying the transition state using the nudged elastic band path technique. The two activation energies agree very well, indicating that transition state theory is applicable for this type of process. PMID:11041947

  20. Yielding and plastic slip in ZnO

    NASA Astrophysics Data System (ADS)

    Sung, T. H.; Huang, J. C.; Hsu, J. H.; Jian, S. R.; Nieh, T. G.

    2012-05-01

    The mechanical properties of ZnO were examined using nanoindentation and microcompression. The modulus, hardness, onset of yielding, and shear strength of the as-grown wafer measured by nanoindentation are 140, 7.1, 12, and 3.6 GPa. The onset of shearing (3.6 GPa) corresponds to the theoretical shear strength. Young's modulus and yield strength measured from micropillar samples were 123 and 3 GPa. The primary slip plane forms an acute angle of 62° with respect to the basal planes, indicting it is pyramidal. Thermal annealing does not affect the residual stresses but can reduce the defect concentration, thus improves the ZnO luminescent properties.

  1. Composite slip table of dissimilar materials for damping longitudinal modes

    DOEpatents

    Gregory, D.L.; Priddy, T.G.; Smallwood, D.O.; Woodall, T.D.

    1991-06-18

    A vibration slip table for use in a vibration testing apparatus is disclosed. The tables comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes. 6 figures.

  2. Wear and Cohesion During Frictional Slip Along Carbonate Faults

    NASA Astrophysics Data System (ADS)

    Reches, Z.; Chen, X.; Boneh, Y.; Madden, A. S.

    2013-12-01

    Our recent experiments with rotary shear of solid rock blocks showed that smoothening of carbonate faults during high-velocity slip leads to significant reduction of both friction and wear-rate. Chen et al. (2013) characterized roughness and friction down to sub-micron scale, and found that smoothing leads to friction reduction. They showed that friction coefficient correlates with surface roughness below 100 nm RMS roughness whereas no weakening occurred with higher roughness. Boneh et al. (2013) sheared limestone and dolomite fault at normal stress up to 7 MPa and slip-velocity up to 1 m/s during steady-state. At low velocities (V < 0.3 m/s), the wear-rate depends on the normal stress, as expected, but at higher velocities the wear-rates are low to vanishing with no dependence on the normal stress. Faults run at high-velocity displayed smooth, hard surfaces. These results allow quantifying the relations between wear, cohesion and friction. Frictional strength is the integrated effect of adhesion (= cohesion), fracturing (= wear), and plastic deformation along a slipping fault. The above results indicate that during the steady-state slip along the smooth, hard, wear-resistant surfaces of the experimental faults occurred with negligible fracturing and plastic deformation. Thus, adhesion became the dominant contributor to the frictional resistance. To test this hypothesis, the experimental cohesion, C, is compared with independently measured calcite adhesion. We use the Mohr diagram to calculate the cohesion of 22 experiments with Dover limestone, ran at velocities 0.005-0.31 m/s and normal stress up to 3 MPa, and 66 experiments with Kasota dolomite, ran at velocities 0.01-0.97 m/s and normal stress up to 7 MPa,. These calculations yielded C = 0.054 +/- 0.055 MPa for the limestone, and C = 0.463 +/- 0.190 MPa for the dolomite. Adhesion can be measured directly with Atomic-Force-Microscope (AFM) by using tiny cantilever with tips with tens of nm radius of curvature. We used several approaches to calculate calcite adhesion from the AFM measurements of Cubillas & Higgins (Geochemical transactions, 2009) and Lomboy et al. (Cement & Concrete Res., 2011) that were conducted on smooth surfaces of cleaved calcite either in air or in solution. We obtained a wide range for values from 0.2 MPa to 4.8 MPa, that are generally equal or higher than the cohesion in the limestone and dolomite experiments. The implications of these results to frictional faulting will be discussed.

  3. Slip and Dilation Tendency Analysis of the Patua Geothermal Area

    DOE Data Explorer

    Faulds, James E.

    Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency analysis for the Patua geothermal system was calculated based on faults mapped in the Hazen Quadrangle (Faulds et al., 2011). Patua lies near the margin between the Basin and Range province, which is characterized by west-northwest directed extension and the Walker Lane province, characterized by west-northwest directed dextral shear. As such, the Patua area likely has been affected by tectonic stress associated with either or both of stress regimes over geologic time. In order to characterize this stress variation we calculated slip tendency at Patua for both normal faulting and strike slip faulting stress regimes. Based on examination of regional and local stress data (as explained above) we applied at shmin direction of 105 to Patua. Whether the vertical stress (sv) magnitude is larger than ...

  4. The Van Fault, Eastern Turkey: A Preliminary Geological Slip Rate

    NASA Astrophysics Data System (ADS)

    Mackenzie, D.; Elliott, J. R.; Altunel, E.; Kurban, Y.; Walker, R. T.; Parsons, B.

    2014-12-01

    We present a preliminary quaternary slip-rate study on the Van fault, the source of the 2011 Mw7.1 reverse-slip earthquake which caused heavy damage to the cities of Van and Ercis, eastern Turkey. From the InSAR solution, we see a strong depth cut-off at 10km depth, above which there was no slip on the fault. We have carried out an investigation of the geomorphological expression of the fault in quaternary material, to determine whether the fault reaches the surface and, if so, whether this upper section could fail in an earthquake. On the western segment of the Van fault, we observe quaternary scarps coincident with the surface projection of the fault segment identified by InSAR, which displace quaternary alluvial fan and lake-bed deposits. These are coincident with the observation of fault gouge in quaternary deposits at a road cutting, providing evidence for a fault reaching the surface and suggesting that the upper section is capable of rupturing seismically. We use structure-from-motion photogrammetry, differential GPS and terrestrial LiDAR to determine offsets on two generations of fault scarps, and the creep offsets from the period following the earthquake. Preliminary radiocarbon and OSL dates from two uplifted terrace surfaces allow us to estimate a late quaternary geological slip-rate for the fault. Following the GPS and InSAR solution of Dogan et al. 2014 (GRL v41,i7), we also present field evidence and satellite image observations confirming the presence of a splay fault within the northern suburbs of Van city, which experienced creep following the 2011 earthquake. This fault is observed to be particularly evident in the early high resolution satellite imagery from the declassified CORONA missions, highlighting the potential for these datasets in identifying faults in areas now covered by urban sprawl. It remains unclear whether this fault could fail seismically. The fault which failed in 2011 is a north dipping reverse fault, unmapped prior to the earthquake. We identify similar geomorphological structures in the surrounding region, highlighting the need for further detailed tectonic mapping of the region.

  5. Braiding Simulation and Slip Evaluation for Arbitrary Mandrels

    NASA Astrophysics Data System (ADS)

    Akkerman, Remko; Villa Rodríguez, Blasimir Hadir

    2007-04-01

    Braiding is a manufacturing process that is increasingly being used to manufacture pre-forms for Resin Transfer Moulding. A fast simulation method is presented for the prediction of the fibre distribution on complex braided parts and complex kinetic situations (e.g. changes in velocity, orientation). The implementation is suited for triangular surface representations as generated by many CAD software packages in use. Experimental results show that the results are sensitive to the friction conditions in particular regions. The friction conditions between the yarns and the mandrel are analysed, leading to the development of a slip indicator.

  6. Slip-Free Rapid Thermal Processing in Single Wafer Furnace

    NASA Astrophysics Data System (ADS)

    Yoo, Woo Sik; Fukada, Takashi; Kitayama, Hirofumi; Takahashi, Nobuaki; Enjoji, Keiichi; Sunohara, Kiyoshi

    2000-06-01

    Defect generation phenomena in Si wafers during atmospheric pressure rapid thermal processing (RTP) in a single wafer furnace (SWF) are investigated as a function of temperature, process time, wafer handling method and speed. The size, shape and spatial distribution of crystal defects generated during RTP were characterized using an optical microscope and X-ray topography. The wafer handling method and speed are found to be very important in controlling defect generation during RTP under given process conditions. Highly reproducible slip-free RTP results were achieved in 200-mm-diameter Si wafers processed at 1100°C for 60 s (up to 5 times) by optimizing the wafer handling method and speed.

  7. Influence of fault connectivity on slip rates in southern California: Potential impact on discrepancies between geodetic derived and geologic slip rates

    NASA Astrophysics Data System (ADS)

    Herbert, Justin W.; Cooke, Michele L.; Marshall, Scott T.

    2014-03-01

    Along the San Bernardino strand of the San Andreas fault (SAF) and across the eastern California shear zone (ECSZ), geologic slip rates differ from those inverted from geodetic measurements, which may partly be due to inaccurate fault connectivity within geodetic models. We employ three-dimensional models that are mechanically compatible with long-term plate motion to simulate both fault slip rates and interseismic surface deformation. We compare results from fault networks that follow mapped geologic traces and resemble those used in block model inversions, which connect the San Jacinto fault to the SAF near Cajon Pass and connect distinct faults within the ECSZ. The connection of the SAF with the San Jacinto fault decreases strike-slip rates along the SAF by up to 10% and increases strike-slip rates along the San Jacinto fault by up to 16%; however, slip rate changes are still within the large geologic ranges along the SAF. The insensitivity of interseismic surface velocities near Cajon Pass to fault connection suggests that inverse models may utilize both an incorrect fault geometry and slip rate and still provide an excellent fit to interseismic geodetic data. Similarly, connection of faults within the ECSZ produces 36% greater cumulative strike-slip rates but less than 17% increase in interseismic velocity. When using overconnected models to invert GPS for slip rates, the reduced off-fault deformation within the models can lead to overprediction of slip rates. While the nature of fault intersections at depth remains enigmatic, fault geometries should be chosen with caution in crustal deformation models.

  8. Phase 1 Program Joint Report

    NASA Technical Reports Server (NTRS)

    Nield, George C. (Editor); Vorobiev, Pavel Mikhailovich (Editor)

    1999-01-01

    This report consists of inputs from each of the Phase I Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.

  9. Joint Communiqu Progress against the

    E-print Network

    1 Joint Communiqué Progress against the Joint Statement of Cooperation between Kalimantan Timur the Joint Statement of Cooperation of 16 September 2010 designed to develop closer ties between Kalimantan the following areas: Livestock Following the 2010 Livestock Workshop held in Balikpapan, a Kalimantan Timur

  10. Joint Seminar UNIVERSITY OF GEORGIA

    E-print Network

    Wang, Lily

    Joint Seminar UNIVERSITY OF GEORGIA DEPARTMENT OF STATISTICS DEPARTMENT OF EPIDEMIOLOGY longitudinal covariates are involved in the modeling of the survival data. A joint likelihood approach has been data. However, in the presence of left truncation, there are additional challenges for the joint

  11. JOINT PERFORMANCE Guide for Optimum

    E-print Network

    July 2012 JOINT PERFORMANCE Guide for Optimum of Concrete Pavements #12; #12;Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2. Report Date Guide for Optimum Joint Performance of Concrete Pavements July 2012 6. Performing

  12. Analysis and Modeling of the Spectrum of the Surface Slip Profile s and Slip Inversions for the 2001 Kokoxili (Tibet) Earthquake

    NASA Astrophysics Data System (ADS)

    Lavallee, D.

    2008-12-01

    The 2001 Kokoxili (Tibet) earthquake provides a unique opportunity to study surfaces slip profiles. The surface slip profiles have been measured along the fault for a distance of the order of 270 km without any significant change in the strike direction. Measurements include the displacement parallel and perpendicular to the fault. However, the recorded earthquake slip profiles are irregularly sampled. Traditional algorithms used to compute the discrete Fourier transform are developed for data sampled at regular spaced intervals. It should be noted that interpolating the slip profile over a regular grid is not appropriate when investigating the spectrum functional behavior or when computing the discrete Fourier transform. Interpolation introduces bias in the estimation of the Fourier transform that adds artificial correlation to the original data. To avoid this problem, we developed an algorithm to compute the Fourier transform of irregularly sampled data. It consists essentially in determining the coefficients that best fit the data to the Sine and Cosine functions at a given wave number. The algorithm is tested by computing the power spectrum of the slip profiles of the Kokoxili earthquakes. In addition, we also compute the power spectrum for the slip inversions computed for the Kokoxili earthquakes. To model the functional behavior of the spectrum curves, we consider two functions: the power law function and the von Karman function. For all the slip models, we compute the parameters of the power law function and the von Karman function that best fits the spectrum curves. We found that the power spectrum curves are best described by a power law function. However the power laws characterizing the slip inversions decrease at a faster pace when compared to the power law computed for the slip profiles recorded at the surface. This result suggests that the correlation embedded in the slip models is larger than the correlation computed for the slip profile recorded at the surface. A similar comparison between the slip profile recorded at the surface on the Arifiye segment of the North Anatolian Fault zone and a kinematic source inversion for the 1999 Izmit (Turkey) earthquake lead to a similar conclusion.

  13. 47 CFR 76.912 - Joint certification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...912 Joint certification. (a) Franchising authorities may apply for joint...data collection, and ratemaking. Franchising authorities jointly certified to regulate...independent rate decisions. (b) Franchising authorities may apply for joint...

  14. 47 CFR 76.912 - Joint certification.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...912 Joint certification. (a) Franchising authorities may apply for joint...data collection, and ratemaking. Franchising authorities jointly certified to regulate...independent rate decisions. (b) Franchising authorities may apply for joint...

  15. Joint Degrees & Promotion towards European Students

    E-print Network

    Di Pillo, Gianni

    Joint Degrees & Promotion towards European Students 26 June 2014 MATTEA CAPELLI & ALESSANDRA GALLERANO INTERNATIONAL OFFICE #12;Joint Degrees and Promotion towards European students Joint degrees guidelines and template for agreements Support to student participation Promotion of Joint Degrees towards

  16. Secondary Fracturing of Europa's Crust in Response to Combined Slip and Dilation Along Strike-Slip Faults

    NASA Technical Reports Server (NTRS)

    Kattenhorn, S. A.

    2003-01-01

    A commonly observed feature in faulted terrestrial rocks is the occurrence of secondary fractures alongside faults. Depending on exact morphology, such fractures have been termed tail cracks, wing cracks, kinks, or horsetail fractures, and typically form at the tip of a slipping fault or around small jogs or steps along a fault surface. The location and orientation of secondary fracturing with respect to the fault plane or the fault tip can be used to determine if fault motion is left-lateral or right-lateral.

  17. No-slip pressures in wall bounded flows

    NASA Astrophysics Data System (ADS)

    Kress, Brian T.; Montgomery, David C.

    1999-11-01

    In incompressible flow, the pressure must obey a Poisson equation gotten from the divergence of the Navier-Stokes (NS) equation. But Poisson equations need boundary conditions, and those for the pressure at no-slip walls are Neumann and Dirichlet both. Many time-dependent tricks around this difficulty have been proposed and some seem to work, but the mathematical issue remains: Which, if any, solenoidal velocity fields that vanish at no-slip walls are acceptable as NS initial conditions? We use a family of solenoidal 2D velocity fields that vanish at plane parallel walls and are periodic in the other direction. Pressures may be found analytically, using the normal or tangential boundary conditions on grad p. Similarities and differences are noted, and limits are considered in which the two differ only slightly. Spectral method dynamical computations, like those of Li et al [1] for the circle, seem feasible. [1] S. Li et al, Phys. Lett. A218, 281 (1996) and Theor. & Comp. Fluid Dyn. 9, 167 (1997).

  18. Quantum phase-slip junction under microwave irradiation

    NASA Astrophysics Data System (ADS)

    Di Marco, A.; Hekking, F. W. J.; Rastelli, G.

    2015-05-01

    We consider the dynamics of a quantum phase-slip junction (QPSJ), a dual Josephson junction, connected to a microwave source with frequency ?mw. With respect to an ordinary Josephson junction, a QPSJ can sustain dual Shapiro steps, consisting of well-defined current plateaus at multiple integers of e ?mw/? in the current-voltage (I -V ) characteristic. The experimental observation of these plateaus has been elusive up to now. We argue that thermal as well as quantum fluctuations can smear the I -V characteristic considerably. In order to understand these effects, we study a current-biased QPSJ under microwave irradiation and connected to an inductive and resistive environment. We find that the effect of the fluctuations is governed by the resistance of the environment and by the ratio of the phase-slip energy and the inductive energy. Our results are of interest for experiments aiming at the observation of dual Shapiro steps in QPSJ devices for the definition of a new quantum current standard.

  19. Suppressing nano-scale stick-slip motion by feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Wu, Re-Bing; Miao, Lei; Xi, Ning; Li, Chun-Wen; Wang, Yue-Chao; Tarn, Tzyh-Jong

    2012-03-01

    When a micro cantilever with a nano-scale tip is manipulated on a substrate with atomic-scale roughness, the periodic lateral frictional force and stochastic fluctuations may induce stick-slip motion of the cantilever tip, which greatly decreases the precision of the nano manipulation. This unwanted motion cannot be reduced by open-loop control especially when there exist parameter uncertainties in the system model, and thus needs to introduce feedback control. However, real-time feedback cannot be realized by the existing virtual reality virtual feedback techniques based on the position sensing capacity of the atomic force microscopy (AFM). To solve this problem, we propose a new method to design real-time feedback control based on the force sensing approach to compensate for the disturbances and thus reduce the stick-slip motion of the cantilever tip. Theoretical analysis and numerical simulations show that the controlled motion of the cantilever tip tracks the desired trajectory with much higher precision. Further investigation shows that our proposal is robust under various parameter uncertainties. Our study opens up new perspectives of real-time nano manipulation.

  20. Persistent earthquake clusters and gaps from slip on irregular faults

    NASA Astrophysics Data System (ADS)

    Parsons, Tom

    2008-01-01

    Earthquake-producing fault systems like the San Andreas fault in California show self-similar structural variation; earthquakes cluster in space, leaving aseismic gaps between clusters. Whether gaps represent overdue earthquakes or signify diminished risk is a question with which seismic-hazard forecasters wrestle. Here I use spectral analysis of the spatial distribution of seismicity along the San Andreas fault (for earthquakes that are at least 2 in magnitude), which reveals that it obeys a power-law relationship, indicative of self-similarity in clusters across a range of spatial scales. To determine whether the observed clustering of earthquakes is the result of a heterogeneous stress distribution, I use a finite-element method to simulate the motion of two rigid blocks past each other along a model fault surface that shows three-dimensional complexity on the basis of mapped traces of the San Andreas fault. The results indicate that long-term slip on the model fault generates a temporally stable, spatially variable distribution of stress that shows the same power-law relationship as the earthquake distribution. At the highest rates of San Andreas fault slip (40mmyr-1), stress patterns produced are stable over a minimum of 25,000 years before the model fault system evolves into a new configuration. These results suggest that although gaps are not immune to rupture propagation they are less likely to be nucleation sites for earthquakes.

  1. Slip ratio in dispersed viscous oil-water pipe flow

    SciTech Connect

    Rodriguez, Iara H.; Yamaguti, Henrique K.B.; de Castro, Marcelo S.; Rodriguez, Oscar M.H. [Department of Mechanical Engineering, Engineering School of Sao Carlos, University of Sao Paulo (USP), Av. Trabalhador Sao Carlense, 400, 13566-970 Sao Carlos, SP (Brazil); Da Silva, Marco J. [Forschungszentrum Dresden-Rossendorf e. V., Institute of Safety Research, PO Box 510119, 01314 Dresden (Germany)

    2011-01-15

    In this article, dispersed flow of viscous oil and water is investigated. The experimental work was performed in a 26.2-mm-i.d. 12-m-long horizontal glass pipe using water and oil (viscosity of 100 mPa s and density of 860 kg/m{sup 3}) as test fluids. High-speed video recording and a new wire-mesh sensor based on capacitance (permittivity) measurements were used to characterize the flow. Furthermore, holdup data were obtained using quick-closing-valves technique (QCV). An interesting finding was the oil-water slip ratio greater than one for dispersed flow at high Reynolds number. Chordal phase fraction distribution diagrams and images of the holdup distribution over the pipe cross-section obtained via wire-mesh sensor indicated a significant amount of water near to the pipe wall for the three different dispersed flow patterns identified in this study: oil-in-water homogeneous dispersion (o/w H), oil-in-water non-homogeneous dispersion (o/w NH) and Dual continuous (Do/w and Dw/o). The phase slip might be explained by the existence of a water film surrounding the homogeneous mixture of oil-in-water in a hidrofilic-oilfobic pipe. (author)

  2. Rolling, slip and traction measurements on low modulus materials

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1985-01-01

    Traction and wear tests were performed on six low modulus materials (LMM). Three different traction tests were performed to determine the suitability of the material for use as traction rollers. These were the rolling, slip and endurance traction tests. For each material the combination LMM on LMM and LMM on steel were evaluated. Rolling traction test were conducted to determine the load - velocity limits, the rolling traction coefficient of the materials and to establish the type of failures that would result when loading beyond the limit. It was found that in general a simple constant rolling traction coefficient was enough to describe the results of all the test. The slip traction tests revealed that the peak traction coefficients were considerably higher than for lubricated traction contacts. The endurance traction tests were performed to establish the durability of the LMM under conditions of prolonged traction. Wear measurements were performed during and after the test. Energetic wear rates were determined from the wear measurements conducted in the endurance traction tests. These values show that the roller wear is not severe when reasonable levels of traction are transmitted.

  3. Constructing constitutive relationships for seismic and aseismic fault slip

    USGS Publications Warehouse

    Beeler, N.M.

    2009-01-01

    For the purpose of modeling natural fault slip, a useful result from an experimental fault mechanics study would be a physically-based constitutive relation that well characterizes all the relevant observations. This report describes an approach for constructing such equations. Where possible the construction intends to identify or, at least, attribute physical processes and contact scale physics to the observations such that the resulting relations can be extrapolated in conditions and scale between the laboratory and the Earth. The approach is developed as an alternative but is based on Ruina (1983) and is illustrated initially by constructing a couple of relations from that study. In addition, two example constitutive relationships are constructed; these describe laboratory observations not well-modeled by Ruina's equations: the unexpected shear-induced weakening of silica-rich rocks at high slip speed (Goldsby and Tullis, 2002) and fault strength in the brittle ductile transition zone (Shimamoto, 1986). The examples, provided as illustration, may also be useful for quantitative modeling.

  4. Aseismic Slip on the Northern Cascadia Subduction Zone: Impacts on Seismic Hazard Estimates

    NASA Astrophysics Data System (ADS)

    Dragert, H.; Mazzotti, S.; Wang, K.

    2002-12-01

    Based on data from the few longer operating continuous GPS sites in southwestern British Columbia and northwestern Washington State, aseismic slip appears to occur repeatedly on the deeper interface of the Cascadia Subduction Zone (CSZ) underlying the eastern Olympics and southern Vancouver Is. The spatial and temporal character of the slip events observed so far have implications for regional seismic hazard estimates. During the period between slips, stress accumulates over an interface region wider than the normal locked/transition zone of the CSZ. However, it appears that there is little long-term stress accumulation on the deeper interface and the potential rupture zone for the next megathrust earthquake remains predominantly offshore. Because of its location downdip of the locked plate interface, a deep aseismic slip produces a small, discrete Coulomb stress increment of the order of 0.01 MPa which moves the locked zone closer to rupture, potentially acting as a trigger for a future great thrust earthquake. The spatial correlation of the boundary of the slip zone with the location of large in-slab earthquakes also suggests a common structural cause or a possible stress interaction. The silent slips and in-slab earthquakes may both be related to a common process of slab dehydration. However, the observed slip events create a Coulomb shadow for normal earthquakes on steeply dipping faults within the descending slab downdip from the slip zone. The region of slip also underlies the areas of high crustal seismicity of Puget Sound and Georgia Strait, but estimates of Coulomb stress changes on crustal faults due to deep slip are extremely sensitive to geometry, thus obscuring patterns of possible crustal stress interactions. To date, no temporal correlations have been found between rates of crustal seismicity and the occurrence of aseismic slip.

  5. Inoculation Against Falls: Rapid Adaptation By Young And Older Adults To Slips During Daily Activities

    PubMed Central

    Pai, Yi-Chung; Bhatt, Tanvi; Wang, Edward; Espy, Deborah; Pavol, Michael J.

    2010-01-01

    Objective To determine whether aging diminishes one’s ability to rapidly learn to resist falls on repeated-slip exposure across different activities of daily living. Design Quasi-experimental controlled trial. Setting Two university-based research laboratories. Participants Young (n=35) and older (n=38) adults underwent slips during walking. Young (n=60) and older (n=41) adults underwent slips during sit-to-stands. All (N=174) were healthy and community-dwelling. Intervention Low-friction platforms induced unannounced blocks of 2–8 repeated slips, interspersed with blocks of 3–5 nonslip trials, during the designated task. Main Outcome Measures The incidence of falls and balance loss. Dynamic stability (based on center-of-mass position and velocity) and limb support (based on hip height) 300 ms after slip onset. Results Under strictly controlled, identical low-friction conditions, all participants experienced balance loss but older adults were over twice as likely as young to fall on the first, unannounced, novel slip in both tasks. Independent of age or task, participants adapted to avoid falls and balance loss, with most adaptation occurring in early trials. By the fifth slip, the incidence of falls and balance loss was less than 5% and 15%, respectively, regardless of age or task. Reductions in falls and balance loss for each task were accomplished through improved control of stability and limb support in both age groups. A rapidly-reversible, age- and task-dependent waning of motor learning occurred after a block of nonslip trials. Adaptation to walk-slips reached steady-state in the second slip block, regardless of age. Conclusions The ability to rapidly acquire fall-resisting skills on repeated-slip exposure remains largely intact at older ages and across functional activities. Thus, repeated-slip exposure might be broadly effective in inoculating older adults against falls. PMID:20298839

  6. Analysis of surface structures of major strike-slip faults

    NASA Astrophysics Data System (ADS)

    Hsieh, Shang Yu; Neubauer, Franz

    2013-04-01

    Strike-slip faults commonly appear with complex fractures and deformation structures on the surface, which also reveal the 3-D geometry with variable structures at depth. The aim of our study is finding the systematic features and correlations of various surface expressions including width, length, height and angle (to the main fault trace) of individual structures like pressure ridges, sag ponds, riedel and anti-riedel faults and oversteps, and also doing a classification with these data. The variation might by caused by distinct convergence angles along strike-slip fault. We study the above mentioned properties on Altyn Tagh fault (ATF), Kunlun, San Andrea and Greendale (Darfield earthquake) faults, which are large strike-slip tectonic structures accommodating major displacement along plate boundaries. Especially the recent events of 2001 Kunlun earthquake and 2010 Darfield earthquake allow a detailed study of structures formed by a single earthquake. Along the fault valley of a 610 km segment of ATF, many large-scale pressure ridges, few pressure basins and horizontal offsets of wadi channels were found; similarly, around 20 features with large scale pressure ridges and pressure basins are found in Carrizo Plain of San Andreas fault. Surface ruptures are uncommon, and dominated by anti-riedels in the case of the Altyn fault. Interpretations show the range of length, width and height in pressure ridges located between 150 and ~6400 m, 35 and ~800 m, and 1 to ~80 m, respectively, along ATF and 255 to ~5750 m, 33 to ~800 m, 2 to ~65 m in Carrizo plain of San Andreas fault. These parameters exhibit a good correlation among each other implying a common cause. Compared with these two strike-slip faults, fault valley portions of the Greendale and Kunlun faults show more surface ruptures for instance riedel shears and anti-riedel structures, which have been caused by the last major earthquake, and also the scale of deformations along the ATF and San Andreas fault is much larger by numerous cumulative earthquakes. Surface ruptures has certain length and width of 5 m to ~200 m, 3 to ~350 m in the Kunlun fault (Lin and Nishikawa, 2011) and 10 to ~450 m, 30 to ~300 m in Greendale fault (Quigley et al., 2012). Beside the scale difference, the statistical approach also applied in the parameters of these surface features, result shows in these four faults, there are specific correlations exist among lengths, width, height and convergence angle which is also the key point to explore the depth of these structures with analog experiments. A likely explanation for the differences between Altyn/San Andreas faults and Kunlun/Glendale fault is the transpressive nature of Altyn/San Andreas faults and the pure strike-slip/transform nature of Glendale/Kunlun faults implying a small convergence angle in the latter case.

  7. Achieving joint benefits from joint implementation

    SciTech Connect

    Moomaw, W.R. [Tufts Univ., Medford, MA (United States)

    1995-11-01

    Joint Implementation (JI) appears to have been born with Applied Energy Services Guatemala project in 1988. That project, to plant 52 million trees, protect existing forests from cutting and fire, and enhance rural development, is being implemented by CARE Guatemala to offset 120 per cent of the emissions of a small coal burning power plant that has been built in Connecticut. Since that time, several utilities and governments have initiated additional projects. Not all of these necessarily consist of tree planting in other countries, but may consist of energy efficiency or energy conservation programs designed to reduce carbon emissions by at least as much as the additional releases from a new facility. All JI projects share the characteristic of linking the release of greenhouse gases in an industrial country with an offset that reduces or absorbs a comparable amount in another country. The emitter in the industrial country is willing to pay for the reduction elsewhere because costs are less than they would be at home.

  8. Laboratory characterization of rock joints

    SciTech Connect

    Hsiung, S.M.; Kana, D.D.; Ahola, M.P.; Chowdhury, A.H.; Ghosh, A. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1994-05-01

    A laboratory characterization of the Apache Leap tuff joints under cyclic pseudostatic and dynamic loads has been undertaken to obtain a better understanding of dynamic joint shear behavior and to generate a complete data set that can be used for validation of existing rock-joint models. Study has indicated that available methods for determining joint roughness coefficient (JRC) significantly underestimate the roughness coefficient of the Apache Leap tuff joints, that will lead to an underestimation of the joint shear strength. The results of the direct shear tests have indicated that both under cyclic pseudostatic and dynamic loadings the joint resistance upon reverse shearing is smaller than that of forward shearing and the joint dilation resulting from forward shearing recovers during reverse shearing. Within the range of variation of shearing velocity used in these tests, the shearing velocity effect on rock-joint behavior seems to be minor, and no noticeable effect on the peak joint shear strength and the joint shear strength for the reverse shearing is observed.

  9. Collective and joint intention

    Microsoft Academic Search

    Raimo Tuomela; Joint Intentions

    2000-01-01

    The paper discussed and analyzes collective and joint intentions of various strength. Thus there are subjectively shared collective\\u000a intentions and intersubjectively shared collective intentions as well as collective intentions which are objectively and intersubjectively\\u000a shared. The distinction between collective and private intentions is considered from several points of view. Especially, it\\u000a is emphasized that collective intentions in the full sense

  10. Joint measurements and Bell inequalities

    E-print Network

    Wonmin Son; Erika Andersson; Stephem M. Barnett; M. S. Kim

    2005-09-20

    Joint quantum measurements of non-commuting observables are possible, if one accepts an increase in the measured variances. A necessary condition for a joint measurement to be possible is that a joint probability distribution exists for the measurement. This fact suggests that there may be a link with Bell inequalities, as these will be satisfied if and only if a joint probability distribution for all involved observables exists. We investigate the connections between Bell inequalities and conditions for joint quantum measurements to be possible. Mermin's inequality for the three-particle Greenberger-Horne-Zeilinger state turns out to be equivalent to the condition for a joint measurement on two out of the three quantum systems to exist. Gisin's Bell inequality for three co-planar measurement directions, meanwhile, is shown to be less strict than the condition for the corresponding joint measurement.

  11. Local Bond StressLocal Bond Stress--Slip Models forSlip Models for Reinforcing Bars & Prestressing Strands inReinforcing Bars & Prestressing Strands in

    E-print Network

    Chao, Shih-Ho

    Fiber) #12;Typical Bond Stress-Slip Responses under Monotonic Loading (12.7 mm Seven-Wire Strand) 12;Typical Bond Stress-Slip Responses under Monotonic Loading (Reinforcing Bars) 12 S i i h N 2 R i f i B g BondStress( S i l R i f t * With Spectra Fiber (2% Fiber Volume Fraction) 4 2 AverageB Spiral

  12. The effective slip length and vortex formation in laminar flow over a rough surface

    E-print Network

    Priezjev, Nikolai V.

    ,4 and promotes convective heat transfer.5­7 In cardiovascular systems, the separation region at the entrance that a flow circulation is developed in the grooves of the rough surface provided that the local boundary toward the bottom of the grooves and the effective slip length increases. When the intrinsic slip length

  13. Study of the pore structure of ceramics prepared by the slip casting method

    NASA Technical Reports Server (NTRS)

    Guzman, I. Y.; Dobysh, A. V.

    1984-01-01

    The porosity of the slip cast Si3N4 is similar to that of pressed Si3N4 formed at 2500 kg/sq cm. The porosity of cast Si oxynitride is equivalent to that of samples stressed at 10,000 kg/sq cm. Crucibles formed from these materials by slip casting have high thermal shock and corrosion resistance.

  14. Analysis of measurements of slip resistance of soiled surfaces on site

    Microsoft Academic Search

    S. Leclercq; M. Tisserand; H. Saulnier

    1997-01-01

    The present study hinges on the use of the PFT (Portable Friction Tester) to assess the slip resistance of floors on site and aims to analyse measurements of slip resistance (602 measurements) that were carried out in 27 different firms on moistened, greasy or dirty floors. The contribution of different factors to the slipperiness of a given soiled surface can

  15. An integrated approach towards identifying age-related mechanisms of slip initiated falls

    Microsoft Academic Search

    Thurmon E. Lockhart

    2008-01-01

    The causes of slip and fall accidents, both in terms of extrinsic and intrinsic factors and their associations are not yet fully understood. Successful intervention solutions for reducing slip and fall accidents require a more complete understanding of the mechanisms involved. Before effective fall prevention strategies can be put into practice, it is central to examine the chain of events

  16. Private Middle School Parents' Perspectives Regarding School-Located Immunization Programs (SLIPs)

    ERIC Educational Resources Information Center

    Venkatesh, Sheila R.; Acosta, Amy B.; Middleman, Amy B.

    2013-01-01

    The perspectives of parents of private middle school students regarding the use of school-located immunization programs (SLIPs) are unknown. Parents of private middle school students in a large, urban setting were surveyed "N" = 1,210) regarding their willingness to use SLIPs. Analyses included frequencies and chi-square analyses. Data…

  17. Slip of a rigid cylinder along a viscoelastic foundation in the presence of friction

    Microsoft Academic Search

    V. A. Belyi; A. D. Lizarev; V. U. Ognev; N. B. Rostanina; P. V. Sysoev

    1974-01-01

    The problem of the slip of a rigid infinitely long cylinder along a viscoelastic foundation in the presence of friction forces dependent on the slip rate is solved in a linear quasistatic arrangement. The effect of the rheological characteristics of the foundation material and other factors on the point displacement of the surface in front of the moving cylinder is

  18. Wall slip and flow of concentrated hard-sphere colloidal suspensions

    E-print Network

    P. Ballesta; G. Petekidis; L. Isa; W. C. K. Poon; R. Besseling

    2012-01-20

    We present a comprehensive study of the slip and flow of concentrated colloidal suspensions using cone-plate rheometry and simultaneous confocal imaging. In the colloidal glass regime, for smooth, non-stick walls, the solid nature of the suspension causes a transition in the rheology from Herschel-Bulkley (HB) bulk flow behavior at large stress to a Bingham-like slip behavior at low stress, which is suppressed for sufficient colloid-wall attraction or colloid-scale wall roughness. Visualization shows how the slip-shear transition depends on gap size and the boundary conditions at both walls and that partial slip persist well above the yield stress. A phenomenological model, incorporating the Bingham slip law and HB bulk flow, fully accounts for the behavior. Microscopically, the Bingham law is related to a thin (sub-colloidal) lubrication layer at the wall, giving rise to a characteristic dependence of slip parameters on particle size and concentration. We relate this to the suspension's osmotic pressure and yield stress and also analyze the influence of van der Waals interaction. For the largest concentrations, we observe non-uniform flow around the yield stress, in line with recent work on bulk shear-banding of concentrated pastes. We also describe residual slip in concentrated liquid suspensions, where the vanishing yield stress causes coexistence of (weak) slip and bulk shear flow for all measured rates.

  19. On the question of whether lubricants fluidize in stick-slip friction.

    PubMed

    Rosenhek-Goldian, Irit; Kampf, Nir; Yeredor, Arie; Klein, Jacob

    2015-06-01

    Intermittent sliding (stick-slip motion) between solids is commonplace (e.g., squeaking hinges), even in the presence of lubricants, and is believed to occur by shear-induced fluidization of the lubricant film (slip), followed by its resolidification (stick). Using a surface force balance, we measure how the thickness of molecularly thin, model lubricant films (octamethylcyclotetrasiloxane) varies in stick-slip sliding between atomically smooth surfaces during the fleeting (ca. 20 ms) individual slip events. Shear fluidization of a film of five to six molecular layers during an individual slip event should result in film dilation of 0.4-0.5 nm, but our results show that, within our resolution of ca. 0.1 nm, slip of the surfaces is not correlated with any dilation of the intersurface gap. This reveals that, unlike what is commonly supposed, slip does not occur by such shear melting, and indicates that other mechanisms, such as intralayer slip within the lubricant film, or at its interface with the confining surfaces, may be the dominant dissipation modes. PMID:26039993

  20. Anisotropic particle in viscous shear flow: Navier slip, reciprocal symmetry, and Jeffery orbit.

    PubMed

    Zhang, Jiaolong; Xu, Xinpeng; Qian, Tiezheng

    2015-03-01

    The hydrodynamic reciprocal theorem for Stokes flows is generalized to incorporate the Navier slip boundary condition, which can be derived from Onsager's variational principle of least energy dissipation. The hydrodynamic reciprocal relations and the Jeffery orbit, both of which arise from the motion of a slippery anisotropic particle in a simple viscous shear flow, are investigated theoretically and numerically using the fluid particle dynamics method [Phys. Rev. Lett. 85, 1338 (2000)]. For a slippery elliptical particle in a linear shear flow, the hydrodynamic reciprocal relations between the rotational torque and the shear stress are studied and related to the Jeffery orbit, showing that the boundary slip can effectively enhance the anisotropy of the particle. Physically, by replacing the no-slip boundary condition with the Navier slip condition at the particle surface, the cross coupling between the rotational torque and the shear stress is enhanced, as manifested through a dimensionless parameter in both of the hydrodynamic reciprocal relations and the Jeffery orbit. In addition, simulations for a circular particle patterned with portions of no-slip and Navier slip are carried out, showing that the particle possesses an effective anisotropy and follows the Jeffery orbit as well. This effective anisotropy can be tuned by changing the ratio of no-slip portion to slip potion. The connection of the present work to nematic liquid crystals' constitutive relations is discussed. PMID:25871211

  1. A Novel Thick-Film Piezoelectric Slip Sensor for a Prosthetic Hand

    Microsoft Academic Search

    Darryl P. J. Cotton; Paul H. Chappell; Andy Cranny; Neil M. White; Steve P. Beeby

    2007-01-01

    The ability to mimic the tactile feedback exhibited by the human hand in an artificial limb is considered advantageous in the automatic control of new multifunctional prosthetic hands. The role of a slip sensor in this tactile feedback is to detect object slip and thus provide information to a controller, which automatically adjusts the grip force applied to a held

  2. Broadband Array Analysis of the 2005 Episodic Tremor and Slip Event in Northern Cascadia

    Microsoft Academic Search

    A. Wech; K. Creager; W. McCausland; A. Frassetto; A. Qamar; S. Derosier; J. Carmichael; S. Malone; D. Johnson

    2005-01-01

    The region of Cascadia from the Olympic Mountains through southern Vancouver Island and down-dip of the subduction megathrust has repeatedly experienced episodes of slow slip. This episodic slip, which has been observed to take place over a period of two to several weeks, is accompanied by a seismic tremor signal. Based on the average recurrence interval of 14 months, the

  3. Development of high-sensitivity slip sensor using special characteristics of pressure conductive rubber

    Microsoft Academic Search

    Seiichi Teshigawara; Kenjiro Tadakuma; Aiguo Ming; Masatoshi Ishikawa; Makoto Shimojo

    2009-01-01

    Even with the eyes closed, humans are able to grip an object with minimal force without such information as the coefficient of friction or the weight. Tactile sensors capable of detecting slippage are necessary for this gripping action to be realized in a robot hand. Heretofore, many slip sensors were developed and produced, but there was not a slip sensor

  4. Grasping force estimation detecting slip by tactile sensor adopting machine learning techniques

    Microsoft Academic Search

    A B M Shawkat Ali

    2008-01-01

    Adequate grasping force estimation and slip detection is a vital problem in wider applications of robots and manipulators in industries as well as in our everyday life. In this paper, a new methodology for slip detection during grasping by robot grippers\\/end-effectors using tactile sensor has been presented. During the object slippage, the tactile sensor in touch with the object surface

  5. Connecting Earthquakes and Violins: Investigations Illustrate Stick-Slip Frictional Motion as a Common Thread

    ERIC Educational Resources Information Center

    Ringlein, James

    2005-01-01

    Violins, earthquakes, and the "singing rod" demonstration all have something in common--stick-slip frictional motion. The application of stick-slip friction can be extended to a ringing wineglass, exotic percussion instruments, car racing, and the latest research on the interplay between surfaces at the atomic level. These examples all involve two…

  6. DYNAMIC SLIP TRANSFER FROM THE DENALI TO TOTSCHUNDA FAULTS, ALASKA: TESTING THEORY FOR FAULT BRANCHING

    E-print Network

    Kame, Nobuki

    1 DYNAMIC SLIP TRANSFER FROM THE DENALI TO TOTSCHUNDA FAULTS, ALASKA: TESTING THEORY FOR FAULT, 2004 [Accepted for publication in BSSA special issue on Denali 2002 earthquake] ABSTRACT We analyze the observed dynamic slip transfer from the Denali to Totschunda faults during the Mw 7.9, November 3, 2002

  7. Denali fault slip rates and Holocene late Pleistocene kinematics of central Alaska

    Microsoft Academic Search

    A. Matmon; D. P. Schwartz; P. J. Haeussler; R. Finkel; J. J. Lienkaemper; H. D. Stenner; Te. Dawson

    2006-01-01

    The Denali fault is the principal intracontinental strike-slip fault accommodating deformation of interior Alaska associated with the Yakutat plate convergence. We obtained the first quantitative late Pleistocene Holocene slip rates on the Denali fault system from dating offset geomorphic features. Analysis of cosmogenic 10Be concentrations in boulders (n = 27) and sediment (n = 13) collected at seven sites, offset

  8. Slipped deformation bands: A new type of cataclastic deformation bands in Western Sinai, Suez rift, Egypt

    E-print Network

    Fossen, Haakon

    is described. Slip surface development is normally constrained to the eventual brittle failure of a deformationSlipped deformation bands: A new type of cataclastic deformation bands in Western Sinai, Suez rift August 2008 Keywords: Deformation bands Cataclasis Fault Porous sandstone a b s t r a c t A type

  9. Volcanic drumbeat seismicity caused by stick-slip motion and magmatic frictional melting

    NASA Astrophysics Data System (ADS)

    Kendrick, J. E.; Lavallée, Y.; Hirose, T.; di Toro, G.; Hornby, A. J.; de Angelis, S.; Dingwell, D. B.

    2014-06-01

    During volcanic eruptions, domes of solidifying magma can form at the volcano summit. As magma ascends it often forms a plug bounded by discrete fault zones, a process accompanied by drumbeat seismicity. The repetitive nature of this seismicity has been attributed to stick-slip motion at fixed loci between the rising plug of magma and the conduit wall. However, the mechanisms for such periodic motion remain controversial. Here we simulate stick-slip motion in the laboratory using high-velocity rotary-shear experiments on magma-dome samples collected from Soufrière Hills Volcano, Montserrat, and Mount St Helens Volcano, USA. We frictionally slide the solid magma samples to generate slip analogous to movement between a magma plug and the conduit wall. We find that frictional melting is a common consequence of such slip. The melt acts as a viscous brake, so that the slip velocity wanes as melt forms. The melt then solidifies, followed by pressure build up, which allows fracture and slip to resume. Frictional melt therefore provides a feedback mechanism during the stick-slip process that can accentuate the cyclicity of such motion. We find that the viscosity of the frictional melt can help define the recurrence interval of stick-slip events. We conclude that magnitude, frequency and duration of drumbeat seismicity depend in part on the composition of the magma.

  10. Slip rate on the Dead Sea transform fault in northern Araba valley (Jordan)

    Microsoft Academic Search

    Y. Klinger; J. P. Avouac; N. Abou Karaki; L. Dorbath; D. Bourles; J. L. Reyss

    2000-01-01

    The Araba valley lies between the southern tip of the Dead Sea and the Gulf of Aqaba. This depression, blanketed with alluvial and lacustrine deposits, is cut along its entire length by the Dead Sea fault. In many places the fault is well defined by scarps, and evidence for left-lateral strike-slip faulting is abundant. The slip rate on the fault

  11. Detailed coseismic slip distribution of the 1944 Tonankai earthquake estimated from tsunami waveforms

    Microsoft Academic Search

    Yuichiro Tanioka; Kenji Satake

    2001-01-01

    Coseismic slip distribution on the fault plane of the 1944 Tonankai earthquake is estimated from inversion of tsunami waveforms. Three improvements from a previous study [Satake, 1993] are made. These are: (1) smaller subfaults are used to resolve detailed slip distribution; (2) the subfaults fit better to the plate interface geometry; and (3) finer and more accurate bathymetry data is

  12. Slip Compensation for a Mars Rover Daniel M. Helmick, Yang Cheng, Daniel S. Clouse,

    E-print Network

    Roumeliotis, Stergios I.

    Slip Compensation for a Mars Rover Daniel M. Helmick, Yang Cheng, Daniel S. Clouse, Max Bajracharya continuous slip compensation for a Mars rover has been designed, implemented, and field-tested. This system is composed of several components that allow the rover to accurately and continuously follow a designated path

  13. Weak hydrogen bonding interactions influence slip system activity and compaction behavior of pharmaceutical powders.

    PubMed

    Khomane, Kailas S; Bansal, Arvind K

    2013-12-01

    Markedly different mechanical behavior of powders of polymorphs, cocrystals, hydrate/anhydrate pairs, or structurally similar molecules has been attributed to the presence of active slip planes system in their crystal structures. Presence of slip planes in the crystal lattice allows easier slip under the applied compaction pressure. This allows greater plastic deformation of the powder and results into increased interparticulate bonding area and greater tensile strength of the compacts. Thus, based on this crystallographic feature, tableting performance of the active pharmaceutical ingredients can be predicted. Recently, we encountered a case where larger numbers of C?H···O type interactions across the proposed slip planes hinder the slip and thus resist plastic deformation of the powder under the applied compaction pressure. Hence, attention must be given to these types of interactions while identifying slip planes by visualization method. Generally, slip planes are visualized as flat layers often strengthened by a two-dimensional hydrogen-bonding network within the layers or planes. No hydrogen bonding should exist between these layers to consider them as slip planes. Moreover, one should also check the presence of C?H···O type interactions across these planes. Mercury software provides an option for visualization of these weak hydrogen bonding interactions. Hence, caution must be exercised while selecting appropriate solid form based on this crystallographic feature. PMID:24136007

  14. Fault slip rates from three-dimensional models of the Los Angeles metropolitan area, California

    E-print Network

    Cooke, Michele

    Fault slip rates from three-dimensional models of the Los Angeles metropolitan area, California Angeles region to use non-planar, geologically representative fault surfaces compiled by the Southern California Earthquake Center Community Fault Model. The fault slip rates from our three-dimensional model

  15. Seismic Moment, Seismicity, and Rate of Slip along Major Fault Zones

    Microsoft Academic Search

    James N. Brune

    1968-01-01

    A straightforward method for computing rates of slip from earthquakes in major fault zones is presented. The slip rate is calculated from the sum of moments for the earthquakes. Rates obtained are in approximate agreement with rates obtained from geodetic measurements or magnetic anomalies, provided that long time samples are considered and provided that adjustments are made in the vertical

  16. Influence of grafting density on wall slip of a polymer melt on a polymer brush

    Microsoft Academic Search

    E. Durliat; H. Hervet; L. Leger

    1997-01-01

    We have investigated the shear flow of a polydimethylsiloxane (PDMS) melt on a PDMS brush of well-controlled density. As the shear rate, dot gamma, is increased, we show the existence of a slip transition from a weak slip regime, where the extrapolation length of the velocity profile, b, is a constant b0, to a strong one, where dot gamma sticks

  17. ForReview.Confidential-ACS Homogeneous shear, wall slip and shear banding of

    E-print Network

    Wang, Shi-Qing

    ForReview.Confidential-ACS Homogeneous shear, wall slip and shear banding of entangled polymeric to Macromolecules #12;ForReview.Confidential-ACS 1 Homogeneous shear, wall slip and shear banding of entangled 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 #12;ForReview.Confidential

  18. Improving Contextual Models of Guessing and Slipping with a Truncated Training Set

    E-print Network

    Aleven, Vincent

    Improving Contextual Models of Guessing and Slipping with a Truncated Training Set Ryan S is the replacement of static estimates of the probability that a student has guessed or slipped with more contextual estimation of these probabilities [2], significantly improving prediction of future performance in one case

  19. The transition from strike–slip to oblique subduction in southeastern Alaska from seismological studies

    Microsoft Academic Search

    Diane I. Doser; Rodolfo Lomas

    2000-01-01

    Body waveform modeling of 11 moderate to large earthquakes within southeastern Alaska has been incorporated with earthquake relocations and the results of previous seismicity studies to examine the transition from strike–slip to oblique subduction in southeastern Alaska. In the Sitka region of extreme southeastern Alaska, earthquakes indicate seismic slip is parallel to the direction of motion between North America and

  20. Path Following using Visual Odometry for a Mars Rover in High-Slip Environments1

    E-print Network

    Roumeliotis, Stergios I.

    1 Path Following using Visual Odometry for a Mars Rover in High-Slip Environments1 Daniel M odometry, full vehicle kinematics, a Kalman filter, and a slip compensation/path follower. Visual odometry Measurement Unit (IMU) and visual odometry. This merged estimate is then compared to the kinematic estimate