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1

Leakage-flow-induced vibration of a tube-in-tube slip joint  

SciTech Connect

The susceptibility of a cantilevered tube conveying water to self-excitation by leakage flow through a slip joint is assessed experimentally. The slip joint is formed by inserting a smaller, rigid tube into the free end of the cantilevered tube. Variations of the slip joint annular gaps and engagement lengths are tested, and several mechanisms for self-excitation are described.

Mulcahy, T.M.

1984-01-01

2

Leakage-flow-induced vibration of a tube-in-tube slip joint. [LMFBR  

SciTech Connect

The susceptibility of a cantilevered tube conveying water to self-excitation by leakage flow through a slip joint is assessed experimentally. The slip joint is formed by inserting a smaller, rigid tube into the free end of the cantilevered tube. Variations of the slip joint annular gaps and engagement lengths are tested, and several mechanisms for self-excitation are described.

Mulcahy, T.M.

1983-06-01

3

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

SciTech Connect

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.

Mulcahy, T.M.

1986-12-01

4

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

SciTech Connect

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.

Mulcahy, T.M.

1986-03-01

5

Avoiding Leakage Flow-Induced Vibration by a Tube-in-Tube Slip Joint.  

National Technical Information Service (NTIS)

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 a...

T. M. Mulcahy

1984-01-01

6

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

SciTech Connect

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.

Mulcahy, T.M.

1986-01-01

7

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

SciTech Connect

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.

Mulcahy, T.M.

1985-01-01

8

Slip joint connector  

NASA Technical Reports Server (NTRS)

A slip joint connector for joining first and second structural elements together is presented. The connector has a first body member attachable to the first structural element and a second body member attachable to the second structural element. The first body member has a male protuberance including a conical portion and the second body member has a conical receptacle for cooperatively receiving the conical portion of the protuberance. The protuberance includes a bridging portion for spacing the conical portion from the remainder of the first body member and the second body member has a well communicating with the conical receptacle for receiving the bridging portion. The conical male portion internally carries a nut while the second body member may receive a bolt through the receptacle to be threadedly received by the nut to secure the first and second body members tightly together.

Thomas, Frank P. (inventor)

1994-01-01

9

Stick-slip friction and wear of articular joints  

PubMed Central

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps—separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints.

Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N.

2013-01-01

10

Effects of multi-joint muscular fatigue on biomechanics of slips.  

PubMed

The objective of the present study was to investigate the effects of multi-joint muscular fatigue on biomechanics of slips. Both lower-limb fatigue and upper-limb fatigue were examined, and the fatiguing exercises involved multi-joint movements to replicate muscular fatigue in realistic scenarios. Sixty healthy young adults participated in the study, and were evenly categorized into three groups: no fatigue, lower-limb fatigue, and upper-limb fatigue. These participants were instructed to walk on a linear walkway, and slips were induced unexpectedly during walking. The results showed that multi-joint muscular fatigue affects biomechanics of slips in all three phases of slips (i.e. initiation, detection, and recovery). In particular, adaptive safer postural control strategies were adopted with the application of both lower-limb fatigue and upper-limb fatigue to maintain the likelihood of slip initiation as in the no fatigue condition. In the phases of detection and recovery, lower-limb fatigue was found to compromise biomechanics of slips while upper-limb fatigue did not show any effects. Based on these findings, minimizing exposures to lower-limb fatigue should be given higher priority compared to upper-limb fatigue when developing interventions to prevent slip-induced falls. In addition, these findings also suggest that interventions aimed at enhancing proprioceptive acuity and increasing muscular strength in the lower limb could also be effective in slip-induced fall prevention. PMID:24182771

Lew, Fui Ling; Qu, Xingda

2014-01-01

11

PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMINES USING A SPINNING TUBE-IN-TUBE REACTOR  

EPA Science Inventory

The high purity, high throughput synthesis of a number of imines (Schiff bases) using a spinning tube-in-tube reactor (STT, Kreido Laboratories, Camarillo, CA) has been carried out. The STT reactor allows the high throughput production of high purity imines from a wide variety of...

12

Controllable fabrication of tube-in-tubes using anodic aluminum oxide templates  

Microsoft Academic Search

We have developed a method to fabricate tube-in-tubes that are relatively long and made in all the pores of porous anodic aluminum oxide (AAO) nano-templates. Relatively a very small amount of Co was deposited in the pores of AAO templates prepared without doing a voltage drop at the end of anodization, and then etched in NaOH solution. This caused the

Lily Kim; Seon Mi Yoon; Jurea Kim; Jung Sang Suh

2004-01-01

13

Combined central slip and volar plate injuries at the PIP joint  

Microsoft Academic Search

PIP joint injuries are common. We describe an unusual injury in which an apparent volar plate avulsion injury was associated with a dorsal, central slip avulsion fracture. We postulate that the mechanism of injury would appear to have been forced flexion with the central ship being avulsed and the volar plate fracture occurring as a secondary impingement fracture. Our two

I. Lo; R. S. Richards

1995-01-01

14

Hydromechanical stability of slip-fit joints in the light-water-breeder-reactor vessel (LWBR Development Program)  

Microsoft Academic Search

An experimental program was conducted to determine the hydro-mechanical stability of slip-fit joints with water flowing through an annular gap. Tests were performed while varying the radial gap width, insertion length, pipe stiffness, eccentricity and exit flow geometry. The results provide an experimental basis from which stable slip-fit joints can be designed over a range of variables related to the

S. G. Beus; R. E. Schwirian

1982-01-01

15

COMMODITY SCALE SYNTHESIS OF 1-METHYLIMIDAZOLE BASED IONIC LIQUIDS USING A SPINNING TUBE-IN-TUBE REACTOR  

EPA Science Inventory

The continuous large-scale preparation of several 1-methylimidazole based ionic liquids was carried out using a Spinning Tube-in-Tube (STT) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Proce...

16

Tube-in-tube reactor as a useful tool for homo- and heterogeneous olefin metathesis under continuous flow mode.  

PubMed

A tube-in-tube reactor was successfully applied in homo- and heterogeneous olefin metathesis reactions under continuous flow mode. It was shown that the efficient removal of ethylene facilitated by connection of the reactor with a vacuum pump significantly improves the outcome of metathesis reactions. The beneficial aspects of this approach are most apparent in reactions performed at low concentration, such as macrocyclization reactions. The established system allows achievement of both improved yield and selectivity, and is ideal for industrial applications. PMID:24167003

Skowerski, Krzysztof; Czarnocki, Stefan J; Knapkiewicz, Pawe?

2014-02-01

17

IN-SITU MONITORING OF PRODUCT STREAMS FROM A SPINNING TUBE-IN-TUBE REACTOR USING A METTLER-TOLEDO REACT-IR  

EPA Science Inventory

A Mettler-Toledo ReactIR system has been used for in-line, real-time monitoring of the product stream from a spinning tube-in-tube reactor (STT®, Kreido Laboratories, Camarillo California). This combination of a process intensified continuous-flow reactor and an in-situ analytic...

18

Coseismic slip distribution of the 2011 Mw 9.0 Tohoku (Japan) earthquake from a joint inversion with GRACE Gravity changes and inland GPS measurements  

NASA Astrophysics Data System (ADS)

The well-observed 2011 MW 9.0 Tohoku, Japan earthquake gained global interest because of its magnitude and the size and impact of the consequent tsunami. Several slip distribution models derived from onshore GPS and/or radar interferometry displacements have been published as well as others derived from teleseismic waveforms and strong motions. These models rely on terrestrial data from Japan and hence are poorly constrained due to the lack of observations in the ocean. In this study, we combine onshore GPS data with gravity changes derived from the Gravity Recovery and Climate Experiments (GRACE) satellites to determine the slip distribution of the main event. Our joint inversion model suggests that the maximum slip of ~44 metres ruptured to the boundary of the Japan trench, near to a bend in this trench located ~120 km south-east of the earthquake epicentre. The joint inversion model shows some distinct shallow-slip patches, which are confirmed by offshore GPS observations; however, those shallow-slip patches were not included in previously published models. Our data suggest that gravitational changes detected by GRACE can make a unique contribution to determining the slip distribution in large events, in particular for oceanic megathrust events with sparse offshore observations. In this paper, the joint inversion strategy is also demonstrated together with an efficient weighting method for different datasets.

Feng, Wanpeng; Li, Zhenhong; Li, Qiong

2013-04-01

19

Slip distribution of the 2003 Tokachi-oki Mw 8.1 earthquake from joint inversion of tsunami waveforms and geodetic data  

Microsoft Academic Search

We study the 2003 Mw 8.1 Tokachi-oki earthquake, a great interplate event that occurred along the southwestern Kuril Trench and generated a significant tsunami. To determine the earthquake slip distribution, we perform the first joint inversion of tsunami waveforms measured by tide gauges and of coseismic displacement measured both by GPS stations and three ocean bottom pressure gauges (PG) for

F. Romano; A. Piatanesi; S. Lorito; K. Hirata

2010-01-01

20

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

SciTech Connect

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.

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

21

Coseismic Slip Model of the 2008 Wenchuan Earthquake Derived From Joint Inversion of InSAR, GPS and Field Data  

NASA Astrophysics Data System (ADS)

We derived a coseismic slip model for the M7.9 2008 Wenchuan earthquake based on radar line of sight displacements from ALOS interferograms, GPS vectors, and geologic field data. The surface rupture of the Wenchuan earthquake extended over 270 km from the epicenter toward the northeast along Longmen Shan thrust belt, on the steep margin of the Tibetan plateau. Available InSAR data provided a nearly complete coverage of the surface deformation along both ascending (fine beam mode) and descending orbits (ScanSAR to ScanSAR mode). The earthquake was modeled using 4 subfaults with variable geometry and dip to capture the simultaneous rupture of both the Beichuan and the Pengguan fault. We inverted the InSAR and GPS data using a non-negative least squares (NNLS) algorithm incorporating the scarp height data as an additional inequality constraint. The inversion scheme considered the first-order effect of topography by perturbing the depth of modeled slip patches according to a local elevation. Our model misfits show that the InSAR and GPS data are highly compatible; the combined inversion yields a 93% variance reduction. The inferred subsurface rupture length is 304 km, which is consistent with the 316 km long distribution of aftershocks. The best-fit model has fault planes that rotate from shallow dip in the south (35 deg) to nearly vertical dip toward the north (70 deg). This result is in a general agreement with the relocated aftershocks. The inferred total geodetic moment of 6.79x10E20 Nm (equivalent to earthquake moment magnitude of 7.8) is nearly equally partitioned into strike-slip (3.61x10E20 Nm) and dip-slip (4.96x10E20 Nm) components. Our rupture model is complex with variations in both depth and rake along two major fault strands. In the southern segment of the Beichuan fault, the slip is mostly thrust (<10 m) and occurred principally in the upper 10 km of the crust; the rupture progressively transformed to right-lateral strike-slip as it propagated northeast (with maximim offsets of 4 to 7 m). A region of maximum slip on the Pengguan fault is limited to a very shallow depth (3.5 km) and is mostly dip-slip (< 9 m). Our coseismic rupture model of the 2008 Wenchuan earthquake, which is mainly based on space geodetic observations, suggests that most of the moment release was limited to the shallow part of the crust (depth less than10 km). We didn’t find any “shallow slip deficit” in the slip-depth distribution of this mixed-mechanism earthquake. Aftershocks were primarily distributed below the section of the fault that ruptured coseismically. This coseismic rupture model will be used in forward models of postseismic deformation to provide insights on mechanisms of postseismic relaxation, the effective rheology of the lower crust and upper mantle, stress transfer, earthquake triggering and future seismic hazard in the area.

Tong, X.; Sandwell, D. T.; Fialko, Y.

2009-12-01

22

Stress perturbations registered by jointing near strike-slip, normal, and reverse faults: Examples from the Ebro Basin, Spain  

Microsoft Academic Search

Stress perturbation patterns created by coeval and preexisting fault planes are characterized by means of detailed mapping and analysis of joint sets in Miocene carbonates of the Tudela area. Strike and spacing of the pervasive N-S joint set have been specially surveyed for this purpose; their spatial variations have been analyzed and interpreted in the light of different theoretical models

J. L. Simón; L. E. Arlegui; C. L. Liesa; A. Maestro

1999-01-01

23

Fault Slip Rates in the Western U.S. From a Joint Fit to Geologic Offsets, GPS Velocities, and Stress Directions  

NASA Astrophysics Data System (ADS)

I merge the SCEC, WGCEP, PBO, & WSM community datasets in neotectonic deformation models for the western US. In California I use: (1) fault traces, dips, and slip senses from WGCEP Fault Models 2.1 or 2.2; (2) fault offset rates and uncertainties obtained by Bird [2007, Geosphere, 3(6)] from offsets in the USGS Paleosites Database; (3) a 2006 California joint GPS solution for interseismic benchmark velocities by Shen, King, Wang, and Agnew; and (4) stress-direction indicators from World Stress Map. In other western United States I use: (5) my collection of fault traces and offset rates as documented in Bird [2007]; and (6) selected GPS velocities from PBO. All are fit by weighted least-squares in kinematic F-E program NeoKinema. As described previously, this program (a) interpolates stress directions to determine their uncertainties, (b) attempts to minimize off-fault strain-rates and align them with stress, and (c) iteratively corrects geodetic velocities from short-term to long-term using local dislocation-in-halfspace corrections. All datasets can be fit at a common level of 1.8 standard errors (RMS or N2 norm). If "acceptable" fit is defined as N2 < 2 for all datasets, there is a range of acceptable models, defining a range of long-term fault slip rates and (anelastic) continuum strain-rates. In preferred model GCN2008060, the mean long-term slip rates for trains of the San Andreas fault are (SE to NW): Coachella 15 mm/a, San Gorgonio Pass-Garnet Hill 6, San Bernardino South 12, San Bernardino North 19, Mojave South 16, Mojave North 17, Big Bend 15, Carrizo 25, Cholame 26, Parkfield 31, Creeping 29, Santa Cruz Mt. 23, Peninsula 18, North Coast 16, and Offshore 9 mm/a. Up to Cajon Pass, these all agree with 2007 WGCEP [2008], but my Mojave N and S and Big Bend rates are much slower, my Carrizo and Cholame rates are marginally slower, and my North Coast and Offshore rates are much slower. These differences are due to greater amounts of permanent (anelastic) straining off the mapped fault traces in NeoKinema, relative to the elastic-microplate models of 2007 WGCEP [2008]. I have not been able to lower the RMS continuum strain rate in these models below 5×10-16 /s (=1.6%/Ma). Such distributed straining results from gaps and geometric incompatibilities in the fault network and from geologic/geodetic discrepancies. This straining probably also occurs on faults (which are not part of WGCEP Fault Models), and it probably also produces earthquakes.

Bird, P.

2008-12-01

24

Biomechanics of slips.  

PubMed

The biomechanics of slips are an important component in the prevention of fall-related injuries. The purpose of this paper is to review the available literature on the biomechanics of gait relevant to slips. This knowledge can be used to develop slip resistance testing methodologies and to determine critical differences in human behaviour between slips leading to recovery and those resulting in falls. Ground reaction forces at the shoe-floor interface have been extensively studied and are probably the most critical biomechanical factor in slips. The ratio of the shear to normal foot forces generated during gait, known as the required coefficient of friction (RCOF) during normal locomotion on dry surfaces or 'friction used/achievable' during slips, has been one biomechanical variable most closely associated with the measured frictional properties of the shoe/floor interface (usually the coefficient of friction or COF). Other biomechanical factors that also play an important role are the kinematics of the foot at heel contact and human responses to slipping perturbations, often evident in the moments generated at the lower extremity joints and postural adaptations. In addition, it must be realized that the biomechanics are dependent upon the capabilities of the postural control system, the mental set of the individual, and the perception of the environment, particularly, the danger of slipping. The focus of this paper is to review what is known regarding the kinematics and kinetics of walking on surfaces under a variety of environmental conditions. Finally, we discuss future biomechanical research needs to help to improve walkway-friction measurements and safety. PMID:11794762

Redfern, M S; Cham, R; Gielo-Perczak, K; Grönqvist, R; Hirvonen, M; Lanshammar, H; Marpet, M; Pai, C Y; Powers, C

2001-10-20

25

Slip stacking  

SciTech Connect

We have started beam studies for ''slip stacking''[1] in the Main Injector in order to increase proton intensity on a target for anti-proton production. It has been verified that the system for slip stacking is working with low intensity beam. For a high intensity operation, we are developing a feedback[2][3] and feedforward system.

Kiyomi Koba and James Steimel

2002-09-19

26

Partitioning Slip  

NSDL National Science Digital Library

This activity consists of four exercises that deal with the partitioning of slip within scenarios involving two or more faults. The first three are hypothetical situations; the last activity focuses on the plate boundary in southern California.

27

The 2011 Mw9.0 Tohoku-Oki Earthquake: Joint occurrence of tectonic stress-driven and lithostatic stress-driven slips along the plate boundary  

NASA Astrophysics Data System (ADS)

The across-arc rupture process of the Tohoku-Oki Earthquake through its hypocenter has following characteristics. (1)Both the inner and outer wedges were ruptured. Slip in the outer wedge (˜40 m) was significantly greater than slip in the inner wedge (˜20 m) (Lay et al., 2011). (2)Rupture occurred initially in the inner wedge and then extended into the outer wedge all the way along the plate boundary to its updip end (Ide et al., 2011; Fujiwara et al., 2011). (3)A number of aftershocks include normal faulting in the inner and outer wedges and return slips in the inner wedge (Asano et al., 2011; Ide et al., 2011). Recent across-arc seismic surveys have revealed the following: (A)The boundary between the seismically active inner and inactive outer wedges is structurally well-defined as the plate bending point, across which the dip of plate interface changes sharply (Ito et al., 2005; Fujie et al., 2006). (B)The outer wedge at relatively shallow depths is dominated by normal faults except near its updip toe, suggesting that the outer wedge is not horizontally compressed over a time scale of the earthquake cycle (Nakamura et al., 2011). We develop a simple spring-block model of the earthquake cycle consistent with all of the above features, supported partially by the elastic taper theory of outer wedge (Hu and Wang, 2006). In our model, slip along the plate boundary cannot easily climb over its bending point around which slip direction changes by about 10 degree. While slip occurs repeatedly in the inner wedge, the outer wedge remains contacted with the underlying plate even if basal friction is low enough to support only the outer wedge in an extensionally critical state (Wang and Hu, 2006). In fact, dominance of normal faults in the outer ridge seems to favor its relatively low basal friction. Repeated slips in the inner wedge and little slip in the outer wedge accumulate stress near the plate bending point. The accumulated stress is eventually released by slip originated in the inner wedge but extending into the outer wedge well across their boundary with a much larger amount of slip in the outer wedge where strain energy has been poorly accumulated at the preseismic stage. Coseismic reduction of the basal friction changes the lithostatic stress system in the outer wedge and causes additional slip accordingly. If the basal friction drops to zero, the lithostatic stress-driven slip brings the inner and outer wedges in a state of horizontal tension on the order of a few tens MPa. With such a complete stress drop assumption (Hasegawa et al., 2011; Nettles et al., 2011) and with model repeating times of once/50yrs and once/500yrs for major and giant earthquakes at a subduction rate of 8 cm/yr, our model predicts inner and outer wedge slips of 2 m and 0 m for a major earthquake, and (20+?) m and (40+2?) m for a giant earthquake like the 2011 Tohoku-Oki Earthquake, where ? and 2? are excess slips of lithostatic stress origin in the inner and outer wedges, which may be estimated by the elastic taper theory if the initial basal friction in the outer wedge is specified. The resultant horizontal tension is relaxed by normal faulting within the inner and outer wedges and return slip along the inner wedge plate boundary.

Fukao, Y.; Hori, T.; Kodaira, S.

2011-12-01

28

Coseismic Kinematic Slip Model for the 12 May 2008 Wenchuan-Beichuan Mw 7.9 Earthquake in Sichuan, China from Joint Inversion of ALOS, Envisat, GPS and Teleseismic Data and Preliminary Postseismic InSAR  

NASA Astrophysics Data System (ADS)

An Mw 7.9 earthquake struck Sichuan province on 12 May 2008 causing catastrophic damage over a large area including the county seats of Wenchuan and Beichuan. ALOS PALSAR coseismic pairs have been processed for eight ascending paths to both interferograms and SAR pixel offsets. Along-track (azimuth) coseismic pixel offsets have large amplitude ripples or waves that are likely due to the ionosphere, and the interferograms show waves in the phase that also are likely due to the ionospheric disturbances that seem to affect the Sichuan area in May and June 2008. Envisat ASAR acquired a number of scenes in Sichuan after the earthquake in high-resolution strip-map modes. Unfortunately, only four descending tracks had prequake acquisitions that allow InSAR analysis, and available temporal and spatial baselines were not optimal. ScanSAR ASAR acquisitions (wide-swath, WS mode) were acquired on tracks that have a number of pre-quake acquisitions, but InSAR coherence at C-band wavelength is marginal for the WS-WS interferograms and adequate only in the plains for the strip-map interferograms. Slip models for the earthquake have been estimated using a joint inversion of the eight PALSAR and four ASAR strip-map interferograms with GPS data published by the Crustal Motion Observation Network of China and teleseismic data. The models show that most of the slip occurred in the upper 10 km of the fault zone. SAR pixel offsets show at least two major faults ruptured. Interferograms and SAR pixel offset measurements show a surface rupture with up to 6 m of oblique right-lateral and thrust slip on a complex set of faults close to what has been called the Beichuan Fault that passes close to the devastated Beichuan. These are consistent with field measurements made by several groups. To the southwest of Beichuan, a second fault to the east of the Beichuan Fault, the Hanwang Fault, a segment of the Pengguan Fault system had significant slip with primarily thrust motion, consistent with field mapping of up to 2 m of vertical displacement. We calculated viscoelastic models of predicted postseismic deformation in the first year after the earthquake using our coseismic static slip model. Projecting into the radar lines of sight yields a prediction for interferometric measurements in the range of 4-6 cm peak to peak. Postseismic interferograms from PALSAR and Envisat ASAR show some indications of the deformation after the earthquake. Large InSAR phase errors due to the propagation through the atmosphere (caused primarily by tropospheric water vapor, but also ionospheric variations for PALSAR) in addition to low coherence in the steep Longmen Shan make it difficult to unambiguously measure the postseismic deformation. The interferograms provide high spatial resolution measurements, but less than optimal postseismic acquisitions cause limitations on the temporal sampling.

Fielding, E. J.; Sladen, A.; Li, Z.; Burgmann, R.; Ryder, I. M.; Avouac, J.

2009-12-01

29

Electro-optical hybrid slip ring  

NASA Astrophysics Data System (ADS)

The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility. A laboratory scale non-contact Electro-Optical Hybrid Slip Ring system was successfully constructed, and its performance was determined. Experimental results affirmed the advantages of this new technology over current slip ring design.

Hong, En

30

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.

Ashcroft, John (Scotia, NY); Campbell, Brian (Scotia, NY); DePoy, David (Clifton Park, NY)

1998-01-01

31

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell. 8 figs.

Ashcroft, J.; Campbell, B.; DePoy, D.

1998-06-30

32

Coseismic and post-seismic slip of the 2009 L'Aquila (central Italy) MW 6.3 earthquake and implications for seismic potential along the Campotosto fault from joint inversion of high-precision levelling, InSAR and GPS data  

NASA Astrophysics Data System (ADS)

After the April 6th 2009 MW 6.3 (ML 5.9) L'Aquila earthquake (central Italy), we re-measured more than 100 km of high-precision levelling lines in the epicentral area. The joint inversion of the levelling measurements with InSAR and GPS measurements, allowed us to derive new coseismic and post-seismic slip distributions and to describe, with high resolution details on surface displacements, the activation and the slip distribution of a secondary fault during the aftershock sequence that struck the Campotosto area (major event MW 5.2). Coseismic slip on the Paganica fault occurred on one main asperity, while the afterslip distribution shows a more complex pattern, occurring on three main patches, including both slips on the shallow portions and on the deeper parts of the rupture plane. The comparison between coseismic and post-seismic slip distributions strongly suggests that afterslip was triggered at the edges of the coseismic asperity. The activation of a segment of the Campotosto fault during the aftershock sequence, with a good correlation between the estimated slipping area, moment release and distribution of aftershocks, raises the opportunity to discuss the local seismic hazard following the occurrence of the 2009 L'Aquila mainshock. The Campotosto fault appears capable of generating earthquakes as large as historical events in the region (M > 6.5) or as small as the ones associated with the 2009 sequence. In the case that the Campotosto fault is accumulating a significant portion of the current interseismic deformation, the 2009 MW > 5 events will have released only a small amount of the accumulated elastic strain, and then a significant hazard still remains in the area. Continuing geodetic monitoring and a densification of the GPS networks in the region are therefore needed to estimate the tectonic loading across the different recognized active fault systems in this part of the Apennines.

Cheloni, D.; Giuliani, R.; D'Anastasio, E.; Atzori, S.; Walters, R. J.; Bonci, L.; D'Agostino, N.; Mattone, M.; Calcaterra, S.; Gambino, P.; Deninno, F.; Maseroli, R.; Stefanelli, G.

2014-05-01

33

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.

34

Friction: Let it slip  

NASA Astrophysics Data System (ADS)

Friction involves a complex set of phenomena spanning a large range of length scales, but experiments assessing the evolution of the slip-front between two dry sliding bodies now reveal that slip can be reasonably well described by linear fracture mechanics theory.

Carpick, Robert W.; Bennewitz, Roland

2014-06-01

35

Contactless Magnetic Slip Ring  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

36

Dynamic scaling in stick-slip friction  

NASA Astrophysics Data System (ADS)

A sandpaper, mounted on a heavy stiff support, was pulled by an elastic line at a very slow speed across a carpet. The sandpaper moved by stick-slip friction. We measured the force required to hold the carpet in place. For each slip, we observed an abrupt change in force proportional to the seismic moment, m, of the slip. We have resolved the duration, t, of slips. The observed joint probability density, p(m,t), satisfies the scaling relation begin{equation} p(m,t)dm dt = ?-?p(frac{m}{?},frac{t}{?^?}) d(frac{m}{?})d(frac{t}{?^?}), where ?, ? are scaling exponents, and ? is a number that represents the change of scale (m and t are given in dimensionless units). It follows that the probability density, p(m), for the seismic moments, and the cumulative distribution, P(M>m), have the scaling forms p(m)˜ m-(?-1),andquad P(M>m)˜ m-? quadwith?=0.68±0.05. The scaling exponent ? is the Gutenberg-Richter exponent for the cumulative magnitude distribution. The probability density, p(t), and the cumulative distribution, P(T>t), for the duration of slips have the scaling forms p(t)˜ t-(?-1),andquad P(M>m)˜ m-? quadwith?=0.95±0.05. Slip magnitude and slip duration are related by m˜ t?, on the average. We found, ?=0.70± 0.05, consistent with the scaling relation, ?=? ?, that follows from equation (1). This work has been supported by The Norwegian Research Council.

Nordhagen, H. O.; Watters Farfan, W. A.; Feder, J.

2003-04-01

37

Slip casting under pressure  

NASA Astrophysics Data System (ADS)

The addition of a pressure during slip casting increases the rate of material deposition and enables larger pieces to be fabricated. In this study, this process has been further developed using monolithic Al2O3 and Al2O3-SiC composites. Slip casting formulations based on both dispersed and coagulated slurries have been analyzed. Excellent results are achieved using coagulated slurries, with no cracking present after drying. The effect of pressure is to increase the green density with a consequent increase in the fired density. In addition, homogeneous microstructures are achieved in the composite system, despite the large difference in particle size used.

Grazzini, H. H.; Wilkinson, D. S.

1992-08-01

38

{110} Slip with {112} slip traces in bcc Tungsten  

PubMed Central

While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane. When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface. We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains.

Marichal, Cecile; Van Swygenhoven, Helena; Van Petegem, Steven; Borca, Camelia

2013-01-01

39

Liquid Metal Slip Ring.  

National Technical Information Service (NTIS)

The liquid metal slip ring described comprises a rotor in the form of a range about an axis and a stator, the rotor being rotatable relative to the stator. The rotor has a channel in which the liquid metal is retained during operation by surface tension. ...

F. D. Berkopec R. R. Lovell D. H. Culp

1979-01-01

40

Liquid Metal Slip Ring.  

National Technical Information Service (NTIS)

A liquid metal slip ring is described which comprises a rotor in the form of a ring about an axis and a stator. The rotor is rotatable relative to the stator and has a channel in which the liquid metal is retained during operation by surface tension. The ...

F. D. Berkopec R. R. Lovell D. H. Culp

1976-01-01

41

Flexible Loop Slip Ring Brush.  

National Technical Information Service (NTIS)

Flexible wire loop slip ring brushes for use in miniaturized gyroscopes. A plurality of flexible wire loop brushes hug or embrace opposite peripheral sides of respective slip rings in resilient sliding contact over a substantial arc for establishing a red...

J. B. Haberl

1980-01-01

42

Inorganic glass ceramic slip rings  

NASA Technical Reports Server (NTRS)

Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

Glossbrenner, E. W.; Cole, S. R.

1972-01-01

43

Nucleation and growth of strike slip faults in granite.  

USGS Publications Warehouse

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

Segall, P.; Pollard, D. P.

1983-01-01

44

Slip on Superhydrophobic Surfaces  

Microsoft Academic Search

This review discusses the use of the combination of surface roughness and hy- drophobicity for engineering large slip at the fluid-solid interface. These su- perhydrophobic surfaces were initially inspired by the unique water-repellent properties of the lotus leaf and can be employed to produce drag reduction in both laminar and turbulent flows, enhance mixing in laminar flows, and amplify diffusion-osmotic

Jonathan P. Rothstein

2010-01-01

45

Slip on Superhydrophobic Surfaces  

Microsoft Academic Search

This review discusses the use of the combination of surface roughness and hydrophobicity for engineering large slip at the fluid-solid interface. These superhydrophobic surfaces were initially inspired by the unique water-repellent properties of the lotus leaf and can be employed to produce drag reduction in both laminar and turbulent flows, enhance mixing in laminar flows, and amplify diffusion-osmotic flows. We

Jonathan P. Rothstein

2010-01-01

46

Optical slip ring for sensor interface applications  

NASA Astrophysics Data System (ADS)

A slip ring is a rotary electrical interface, collector, swivel or joint. It is a component or architecture that can perform continuous data transfer between a rotary and stationary structure. A few of the numerous approaches for transferring data include contact and non-contact methods which use wires, radio waves, optical fibers and even liquid as the transfer media. However, they all suffer inherent drawbacks in durability, reliability, stability, electromagnetic interference and speed. The system introduced in this paper alleviates many of these issues by employing a wireless through the air optical solution.

Hong, En; Krishnamurthy, Abhishek; Gregory, Don A.; Anderson, Sean

2006-06-01

47

Low-Friction Joint for Robot Fingers  

NASA Technical Reports Server (NTRS)

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.

Ruoff, C. F.

1985-01-01

48

Formation and Suppression of Strike-Slip Fault Systems  

NASA Astrophysics Data System (ADS)

Strike-slip faults are a defining feature of plate tectonics, yet many aspects of their development and evolution remain unresolved. For intact materials and/or regions, a standard sequence of shear development is predicted from physical models and field studies, commencing with the formation of Riedel shears and culminating with the development of a throughgoing fault. However, for materials and/or regions that contain crustal heterogeneities (normal and/or thrust faults, joints, etc.) that predate shear deformation, kinematic evolution of strike-slip faulting is poorly constrained. We present a new plane-stress finite-strain physical analog model developed to investigate primary deformation zone evolution in simple shear, pure strike-slip fault systems in which faults or joints are present before shear initiation. Experimental results suggest that preexisting mechanical discontinuities (faults and/or joints) have a marked effect on the geometry of such systems, causing deflection, lateral distribution, and suppression of shears. A lower limit is placed on shear offset necessary to produce a throughgoing fault in systems containing preexisting structures. Fault zone development observed in these experiments provides new insight for kinematic interpretation of structural data from strike-slip fault zones on Earth, Venus, and other terrestrial bodies.

Curren, Ivy S.; Bird, Peter

2014-03-01

49

Small sized slip-ring capsule endurance testing  

NASA Astrophysics Data System (ADS)

Slip-ring capsules are mechanical units used to carry electrical signals or power currents through a rotating joint. They are used either in solar array drive mechanisms (SADM) or in scientific instruments like radiometers. Analyses of the latest missions show that the slip-rings requirements are more and more demanding. For example, the number of in-orbit mechanical cycles keeps increasing. As a result, a signal slip-ring technology, which had been successfully tested for a given need, now has to improve its performances. It was therefore interesting to try to reach the slip-rings technical limits by testing them beyond the required performance of already known space missions. Slip-rings units are currently used in mechanisms such as SADM for the CNES Proteus and Myriade satellite family. They can be also found in the payload instruments of the Megha-Tropiques satellite project, namely Madras and Scarab. A selected hardware was tested at the mechanism endurance laboratory of the CNES, in Toulouse. The typical in-orbit rotation speed was increased in order to limit the test duration to 2 years. The main interest of this work was to provide a continuous slip-ring performance status and a large set of engineering data. The main test results are presented and discussed. The following lines also report a part of the hardware detailed inspection and the lessons learned.

Mondier, Jean-Bernard

2005-07-01

50

Mechanism of slip and twinning  

NASA Technical Reports Server (NTRS)

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.

Rastani, Mansur

1992-01-01

51

Slip flow in graphene nanochannels  

NASA Astrophysics Data System (ADS)

We investigate the hydrodynamic boundary condition for simple nanofluidic systems such as argon and methane flowing in graphene nanochannels using equilibrium molecular dynamics simulations (EMD) in conjunction with our recently proposed method [J. S. Hansen, B. D. Todd, and P. J. Daivis, Phys. Rev. E 84, 016313 (2011)]. We first calculate the fluid-graphene interfacial friction coefficient, from which we can predict the slip length and the average velocity of the first fluid layer close to the wall (referred to as the slip velocity). Using direct nonequilibrium molecular dynamics simulations (NEMD) we then calculate the slip length and slip velocity from the streaming velocity profiles in Poiseuille and Couette flows. The slip lengths and slip velocities from the NEMD simulations are found to be in excellent agreement with our EMD predictions. Our EMD method therefore enables one to directly calculate this intrinsic friction coefficient between fluid and solid and the slip length for a given fluid and solid, which is otherwise tedious to calculate using direct NEMD simulations at low pressure gradients or shear rates. The advantages of the EMD method over the NEMD method to calculate the slip lengths/flow rates for nanofluidic systems are discussed, and we finally examine the dynamic behaviour of slip due to an externally applied field and shear rate.

Kannam, Sridhar Kumar; Todd, B. D.; Hansen, J. S.; Daivis, Peter J.

2011-10-01

52

Slip flow in graphene nanochannels.  

PubMed

We investigate the hydrodynamic boundary condition for simple nanofluidic systems such as argon and methane flowing in graphene nanochannels using equilibrium molecular dynamics simulations (EMD) in conjunction with our recently proposed method [J. S. Hansen, B. D. Todd, and P. J. Daivis, Phys. Rev. E 84, 016313 (2011)]. We first calculate the fluid-graphene interfacial friction coefficient, from which we can predict the slip length and the average velocity of the first fluid layer close to the wall (referred to as the slip velocity). Using direct nonequilibrium molecular dynamics simulations (NEMD) we then calculate the slip length and slip velocity from the streaming velocity profiles in Poiseuille and Couette flows. The slip lengths and slip velocities from the NEMD simulations are found to be in excellent agreement with our EMD predictions. Our EMD method therefore enables one to directly calculate this intrinsic friction coefficient between fluid and solid and the slip length for a given fluid and solid, which is otherwise tedious to calculate using direct NEMD simulations at low pressure gradients or shear rates. The advantages of the EMD method over the NEMD method to calculate the slip lengths/flow rates for nanofluidic systems are discussed, and we finally examine the dynamic behaviour of slip due to an externally applied field and shear rate. PMID:22010725

Kannam, Sridhar Kumar; Todd, B D; Hansen, J S; Daivis, Peter J

2011-10-14

53

Coherent quantum phase slip.  

PubMed

A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology. PMID:22517162

Astafiev, O V; Ioffe, L B; Kafanov, S; Pashkin, Yu A; Arutyunov, K Yu; Shahar, D; Cohen, O; Tsai, J S

2012-04-19

54

Ultrasonography for diagnosis of slipped capital femoral epiphysis. Comparison with radiography in 9 cases.  

PubMed

In 7 of 8 patients with non-acute slipped capital femoral epiphysis, the slip was visualized by ultrasound. The mean epiphyseal displacement was 6.0 mm, measured on an anterior ultrasound scan. Grading of slip severity by ultrasound was consistent with the radiographic assessment. Two patients had a moderate hip joint effusion which did not affect the final outcome, whereas one patient with an acute slip had a pronounced effusion, and necrosis of the epiphysis occurred. The anteversion angles of the affected hips were reduced as compared to those of the normal hips. It was concluded that ultrasonography was reliable in detecting pronounced and mild degrees of epiphyseal slips, whereas minimal slips could be missed. The detection of hip effusion is important because a tamponade may cause vascular impairment of the epiphysis, unless aspirated. PMID:1471516

Terjesen, T

1992-12-01

55

{110} Slip with {112} slip traces in bcc Tungsten.  

PubMed

While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane. When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface. We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains. PMID:23989456

Marichal, Cecile; Van Swygenhoven, Helena; Van Petegem, Steven; Borca, Camelia

2013-01-01

56

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

PubMed Central

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.

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

2009-01-01

57

Advances in hip preservation after slipped capital femoral epiphysis.  

PubMed

The metaphyseal deformity, in even a mild slipped capital femoral epiphysis (SCFE), results in acetabular labral and cartilage injury. SCFE is the most extreme form of femoroacetabular impingement, and the mechanism of cartilage and labral injuries is similar. Recent surgical advances for treating femoroacetabular impingement have made it possible to consider applying these techniques to the surgical treatment of SCFE deformities to lessen the risk of secondary osteoarthritis. The goals of treatment are to arrest slip progression and restore normal proximal femoral anatomy, thereby decreasing damage to the hip joint secondary to impingement. In situ pinning is the most effective treatment to halt short-term slip progression; outcomes are favorable in many hips. In medical centers with substantial experience with hip preservation techniques, open or arthroscopic osteochondroplasty can be used to treat mild SCFE, and a modified Dunn epiphyseal reorientation can be used for more severe deformities to decrease the potential for secondary osteoarthritis. PMID:23395046

Morakis, Emmanouil; Sink, Ernest L

2013-01-01

58

Suppression of strike-slip fault systems  

NASA Astrophysics Data System (ADS)

In orogens elongated parallel to a great circle about the Euler pole for the two bounding plates, theory requires simple-shear deformation in the form of distributed deformation or velocity discontinuities across strike-slip faults. This type of deformation, however, does not develop at all plate boundaries requiring toroidal motion. Using the global plate boundary model, PB2002 [Bird, 2003], as the basis for identifying areas where expected simple-shear deformation is absent or underdeveloped, it was also possible to identify two potential causes for this behavior: (1) the presence of extensive fracturing at right angles to the shear plane and (2) regional cover of flood basalts or andesites with columnar joints. To test this hypothesis, a new plane-stress finite-strain model was developed to study the effects of such pre-existing structures on the development of simple shear in a clay cake. A homogenous kaolinite-water mixture was poured into a deforming parallelogram box and partially dried to allow for brittle and plastic deformation at and below the surface of the clay, respectively. This was floated on a dense fluid foundation, effectively removing basal friction, and driven by a motor in a sinistral direction from the sides of the box. Control experiments produced classic Riedel model fault assemblages and discrete, through-going primary deformation zones (PDZs); experiments with pre-existing structures developed the same, though subdued and distributed, fault assemblages but did not develop through-going PDZs. Although formation of strike-slip faults was underdeveloped at the surface in clay with pre-existing structures, offset within the clay cake (measured, with respect to a fixed point, by markers on the clay surface) as a fraction of total offset of the box was consistently larger than that of the control experiments. This suggests that while the extent of surface faulting was lessened in clay with pre-existing structures, slip was still occurring at depth. Selected areas on Earth with anomalously undeveloped strike-slip faulting where plate models would predict otherwise were compared with results from the analog model experiments in this study. Physical similarities between this model and Brothers Fault Zone (BFZ), Walker Lane (WL) and the South Iceland Seismic Zone (SISZ) imply that strike-slip faulting may be suppressed at the surface in these regions due to the presence of pre-existing structures. Filled circles show offset required for breakthrough faulting, empty circles denote lower limit of breakthrough. Triangles show clay offset as a fraction of box offset. Note that clays with pre-existing structures showed larger offsets although breakthrough did not occur.

Curren, I. S.

2012-12-01

59

Stabilizing Stick-Slip Friction  

NASA Astrophysics Data System (ADS)

Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality.

Capozza, Rosario; Rubinstein, Shmuel M.; Barel, Itay; Urbakh, Michael; Fineberg, Jay

2011-07-01

60

Secular Variation in Slip (Invited)  

NASA Astrophysics Data System (ADS)

Faults show temporal variations in slip rate at time scales ranging from the hours following a major rupture to the millions of years over which plate boundaries reorganize. One such behavior is secular variation in slip (SVS), which we define as a pulse of accelerated strain release along a single fault that occurs at a frequency that is > 1 order of magnitude longer than the recurrence interval of earthquakes within the pulse. Although numerous mechanical models have been proposed to explain SVS, it has proven much harder to measure long (5-500 kyr) records of fault displacement as a function of time. Such fault-slip histories may be obtained from morphochronologic data, which are measurements of offset and age obtained from faulted landforms. Here we describe slip-history modeling of morphochronologic data and show how this method holds promise for obtaining long records of fault slip. In detail we place SVS in the context of other types of time-varying fault-slip phenomena, explain the importance of measuring fault-slip histories, summarize models proposed to explain SVS, review current approaches for measuring SVS in the geologic record, and illustrate the slip-history modeling approach we advocate here using data from the active, left-slip Altyn Tagh fault in NW Tibet. In addition to SVS, other types of temporal variation in fault slip include post-seismic transients, discrepancies between geologic slip rates and those derived from geodetic and/or paleoseismic data, and single changes in slip rate resulting from plate reorganization. Investigating secular variation in slip is important for advancing understanding of long-term continental deformation, fault mechanics, and seismic risk. Mechanical models producing such behavior include self-driven mode switching, changes in pore-fluid pressure, viscoelasticity, postseismic reloading, and changes in local surface loads (e.g., ice sheets, large lakes, etc.) among others. However, a key problem in testing these models is the paucity of long records of fault slip. Paleoseismic data are unlikely to yield such histories because measurements of the slip associated with each event are generally unavailable and long records require large accumulated offsets, which can result in structural duplication or omission of the stratigraphic records of events. In contrast, morphochronologic data capture both the age and offset of individual piercing points, although this approach generally does not resolve individual earthquake events. Because the uncertainties in both age and offset are generally large (5-15%) for individual markers, SVS is best resolved by obtaining suites of such measurements, in which case the errors can be used to reduce the range of slip histories common to all such data points. A suite of such data from the central Altyn Tagh fault reveals a pulse of accelerated strain release in the mid Holocene, with ~20 m of slip being released from ~6.7 to ~5.9 ka at a short-term rate (~28 mm/yr) that is 3 times greater than the average rate (~9 mm/yr). We interpret this pulse to represent a cluster of two to six, Mw > 7.2 earthquakes. To our knowledge, this is the first possible earthquake cluster detected using morphochronologic techniques.

Cowgill, E.; Gold, R. D.

2010-12-01

61

Slipping and Rolling Wheel Model  

NSDL National Science Digital Library

The EJS Slipping and Rolling Wheel Model shows the motion of a wheel rolling on a floor subject to friction. The simulation allows the user to change the initial translational and rotational velocities of the wheel, v and ω, the mass, radius, and mass distribution, R, m, and C of the wheel. By controlling these variables, the dynamics of the wheel can be changed to show the sliding, then rolling without slipping, of the wheel. The Slipping and Rolling Wheel Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_newton_SlippingRollingWheel.jar file will run the program if Java is installed. The user can modify this simulation if EJS is installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Christian, Wolfgang; Belloni, Mario

2009-02-26

62

Packer slips for CRA completion  

Microsoft Academic Search

This patent describes a slip anchor stud for use in combination with a well packer comprising a main body portion having a length dimension and a radius dimension, a plurality of ribs formed on the main body portion.

R. B. Wheeler; A. T. Jackson

1992-01-01

63

Bond–slip models for FRP sheets\\/plates bonded to concrete  

Microsoft Academic Search

An accurate local bond–slip model is of fundamental importance in the modelling of FRP-strengthened RC structures. In this paper, a review of existing bond strength models and bond–slip models is first presented. These models are then assessed using the results of 253 pull tests on simple FRP-to-concrete bonded joints, leading to the conclusion that a more accurate model is required.

X. Z. Lu; J. G. Teng; L. P. Ye; J. J. Jiang

2005-01-01

64

Earthquake slip distribution estimation, using a random vector approach  

NASA Astrophysics Data System (ADS)

InSAR and/or GNSS data are routinely used to invert for the slip distribution on faults that rupture during earthquakes. Where exactly slip occurred has implications for future seismic hazard. However, in order to regularize the inversion, extra assumptions about the smoothness of the slip distribution are usually included, which do not have a physical basis. Here we propose a new approach for constraining the slip distribution based on a random vector model following a von Karman autocorrelation function. While this approach also has no physical basis, it does have empirical support from a stochastic analysis of seismic finite-source slip inversions (Mai and Beroza, 2002). We implement the random vector constraint in a Bayesian fashion and use a Markov chain Monte Carlo (MCMC) algorithm to derive the posterior joint probability distribution for each of the slipping patches. The von Karman function depends on two parameters: correlation length and Hurst number (related to fractal dimension). We use histograms from the stochastic analysis for these two parameters, which differ in along-strike and down-dip directions, to derive prior probability distributions, but allow them to vary during the inversion as hyperparameters. We also let the model parameters that control the fault geometry vary freely. In other inversion approaches these are usually fixed prior to inversion for distributed slip, due primarily to the difficulty in searching the resulting model space within a reasonable CPU time. To overcome this problem we have implemented a variation to the usual MCMC approach, in which the step size for each of the model parameters is regularly updated to optimize convergence time. We have applied our approach to a number of earthquakes and find that the results sometimes differ markedly to those incorporating the common Laplacian smoothing constraint. In addition, the fast run times mean that this approach could be routinely applied to data from the upcoming Sentinel-1 mission to automatically derive slip distributions for all earthquakes that cause significant surface displacement. References: Mai, P. M., and G. C. Beroza (2002), A spatial random field model to characterize complexity in earthquake slip, J. Geophys. Res., 107(B11), 2308.

Hooper, A. J.

2012-12-01

65

Stabilizing Stick-Slip Friction  

NASA Astrophysics Data System (ADS)

Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality. Reference: Rosario Capozza, Shmuel M. Rubinstein, Itay Barel, Michael Urbakh, and Jay Fineberg, Physical Review Letters 107, 024301 (2011).

Fineberg, J.; Urbakh, M.; Rubinstein, S. M.

2011-12-01

66

Strike Slip Tectonics on Enceladus  

NASA Astrophysics Data System (ADS)

One of the most surprising characteristics of Enceladus is its intense tectonic activity on its surface. This tectonic activity can be seen as faults and ridges that deform the ancient craterized terrains and generate the actual topography. The main structure that defines the visible tectonics of the satellite is Samarkanda Sulci, which it has been interpreted as a extensional rift but we have reinterpreted as a strike slip zone. The slip has a sinistral movement and a deduced NNW-SSE direction of compression. The changes in the orientation of the fault plane generate directional duplex, some trans-tensional and others trans-pressional.

Gomez, D.; Prieto, O.; Rodriguez, M. A.

1996-03-01

67

Slipped-strand DNAs formed by long (CAG)·(CTG) repeats: slipped-out repeats and slip-out junctions  

Microsoft Academic Search

The disease-associated expansion of (CTG)·(CAG) repeats is likely to involve slipped-strand DNAs. There are two types of slipped DNAs (S-DNAs): slipped homoduplex S-DNAs are formed between two strands having the same number of repeats; and heteroduplex slipped intermediates (SI-DNAs) are formed between two strands having dif- ferent numbers of repeats. We present the first char- acterization of S-DNAs formed by

Christopher E. Pearson; Mandy Tam; Yuh-Hwa Wang; S. Erin Montgomery; Arvin C. Dar; John D. Cleary; Kerrie Nichol

68

Slip rate and tremor genesis in Cascadia  

NASA Astrophysics Data System (ADS)

many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

Wech, Aaron G.; Bartlow, Noel M.

2014-01-01

69

The Role of Water in Slip Casting.  

National Technical Information Service (NTIS)

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. ...

R. A. Mccauley G. W. Phelps

1984-01-01

70

Slip liner grouting method and system  

SciTech Connect

This patent describes an apparatus for controlling the movement of a slip liner in a sewer prior to and during the grouting of the slip liner in position in the sewer to prevent fluid from leaking through the walls of the the sewer. The sewer and the slip liner having water therein during the grouting of the slip liner in position in the sewer. The apparatus to control the movement of the slip liner in the sewer prior to and during the grouting of the slip liner in position in the sewer by preventing movement of the slip liner with respect to the sewer during the grouting of the slip liner in position in the sewer.

Lee, L.D.

1989-12-26

71

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

SciTech Connect

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.

Koteras, J.R.

1994-02-01

72

Interaction of fault slip and lithospheric creep  

Microsoft Academic Search

The interaction of fault slip and lithospheric creep is studied on the basis of an idealized viscoelastic model of the lithosphere. Under a constant average driving stress the model displays a periodic slip-creep-slip limit cycle. A simple formula is found that relates effective lithospheric viscosity to fault depth, long-time average slip rate, and dynamic driving stress tauAD=tauA -tauD, where tauA

Bernard Budiansky; John C. Amazigo

1976-01-01

73

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.

74

Proper orthogonal decomposition of the dynamics in bolted joints  

Microsoft Academic Search

Joints play an important role in the dissipation of vibration energy in built-up structures. The highly nonlinear nature of joints with micro-slip is the main hurdle in developing a reduced-order model which can simulate the dynamic behaviour of a joint for a wide range of excitation conditions and geometries. In this paper, the proper orthogonal decomposition is applied to joint

Abdur Rauf Khattak; Seamus Garvey; Atanas Popov

2010-01-01

75

Slip and flow in soft particle pastes.  

PubMed

Concentrated dispersions of soft particles are shown to exhibit a generic slip behavior near smooth surfaces. Slip results from a balance between osmotic forces and noncontact elastohydrodynamic interaction between the squeezed particles and the wall. A model is presented that predicts the slip properties and provides insight into the behavior of the bulk paste. PMID:15169454

Meeker, Steven P; Bonnecaze, Roger T; Cloitre, Michel

2004-05-14

76

Slip, stick, and reverse slip characteristics during dynamic fibre pullout  

NASA Astrophysics Data System (ADS)

Inertial effects in the mechanism of fibre pullout (or push-in) are examined, with emphasis on how the rate of propagation of stress waves along the fibre, and thence the pullout dynamics, are governed by friction and the propagation of companion waves excited in the matrix. With a simple shear lag model (assuming zero debond energy at the fibre/matrix interface), the effect of uniform frictional coupling between the fibre and the matrix is accounted for in a straightforward way. Analytical solutions are derived when the pullout load increases linearly in time. The process zone of activated material is generally divided into two or three domains along the axis of the fibre. Within these domains, slip in the sense implied by the load, slip in the opposite sense (reverse slip), and stick may be observed. The attainable combinations define three regimes of behavior, which are realized for different material parameter values. The elastodynamic problem is also solved more accurately using a plane stress finite element method, with friction represented by an interfacial cohesive zone. The predictions of the shear lag theory are broadly confirmed.

Sridhar, N.; Yang, Q. D.; Cox, B. N.

2003-07-01

77

Slipped-strand DNAs formed by long (CAG)?(CTG) repeats: slipped-out repeats and slip-out junctions  

PubMed Central

The disease-associated expansion of (CTG)·(CAG) repeats is likely to involve slipped-strand DNAs. There are two types of slipped DNAs (S-DNAs): slipped homoduplex S-DNAs are formed between two strands having the same number of repeats; and heteroduplex slipped intermediates (SI-DNAs) are formed between two strands having different numbers of repeats. We present the first characterization of S-DNAs formed by disease-relevant lengths of (CTG)·(CAG) repeats which contained all predicted components including slipped-out repeats and slip-out junctions, where two arms of the three-way junction were composed of complementary paired repeats. In S-DNAs multiple short slip-outs of CTG or CAG repeats occurred throughout the repeat tract. Strikingly, in SI-DNAs most of the excess repeats slipped-out at preferred locations along the fully base-paired Watson–Crick duplex, forming defined three-way slip-out junctions. Unexpectedly, slipped-out CAG and slipped-out CTG repeats were predominantly in the random-coil and hairpin conformations, respectively. Both the junctions and the slip-outs could be recognized by DNA metabolizing proteins: only the strand with the excess repeats was hypersensitive to cleavage by the junction-specific T7 endonuclease I, while slipped-out CAG was preferentially bound by single-strand binding protein. An excellent correlation was observed for the size of the slip-outs in S-DNAs and SI-DNAs with the size of the tract length changes observed in quiescent and proliferating tissues of affected patients—suggesting that S-DNAs and SI-DNAs are mutagenic intermediates in those tissues, occurring during error-prone DNA metabolism and replication fork errors.

Pearson, Christopher E.; Tam, Mandy; Wang, Yuh-Hwa; Montgomery, S. Erin; Dar, Arvin C.; Cleary, John D.; Nichol, Kerrie

2002-01-01

78

Slip speed feedback for grip force control.  

PubMed

Grasp stability in the human hand has been resolved by means of an intricate network of mechanoreceptors integrating numerous cues about mechanical events, through an ontogenetic grasp practice. An engineered prosthetic interface introduces considerable perturbation risks in grasping, calling for feedback modalities that address the underlying slip phenomenon. In this study, we propose an enhanced slip feedback modality, with potential for myoelectric-based prosthetic applications, that relays information regarding slip events, particularly slip occurrence and slip speed. The proposed feedback modality, implemented using electrotactile stimulation, was evaluated in psychophysical studies of slip control in a simplified setup. The obtained results were compared with vision and a binary slip feedback that transmits on-off information about slip detection. The slip control efficiency of the slip speed display is comparable to that obtained with vision feedback, and it clearly outperforms the efficiency of the on-off slip modality in such tasks. These results suggest that the proposed tactile feedback is a promising sensory method for the restoration of stable grasp in prosthetic applications. PMID:22614517

Damian, D D; Arita, A H; Martinez, H; Pfeifer, R

2012-08-01

79

What Happens to Bolt Tension in Large Joints.  

National Technical Information Service (NTIS)

An experimental study was made of the changes in bolt tension in high-strength A325 and A490 bolts connecting A440 (high-strength) and A514 (constructional alloy) steel joints. Until major slip occurred in the large bolted joints, high-strength steel bolt...

G. H. Sterling J. J. Wallaert J. W. Fisher

1965-01-01

80

MODELLING OF RC BEAM-COLUMN JOINTS AND STRUCTURAL WALLS  

Microsoft Academic Search

The deformation of beam-column joints may contribute significantly to drift of reinforced concrete (RC) frames. In addition, failure may occur in the joints due to cumulative concrete crushing from applied beam and column moments, bond slip of embedded bars or shear failure as in the case of existing frames with nonductile detailing. When subjected to earthquake loading, failure in RC

Maged A. Youssef; A. GHOBARAH

2001-01-01

81

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

NASA Astrophysics Data System (ADS)

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).

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

2011-12-01

82

Animations of Episodic Tremor and Slip  

NSDL National Science Digital Library

This collection of animations shows episodic tremor and slip (slow earthquakes) from a subducting plate with locked, slow slip, and no slip zones. The first two show wood blocks being pulled over sandpaper to simulate buildup and release of strain in locked and slow slip zones of a subducting tectonic plate, and to simulate episodic movement of a subducting tectonic plate. Graphs display time versus strain or time versus distance for each of the blocks. The third animation shows a cross-section through a subducting plate illustrating the movements of a GPS station as subduction proceeds. Graphs show time versus distance under three scenarios: locked plates, slow slip, and no slip. The last animation shows horizontal movement of a GPS station as a graph displays time versus distance and a seismogram denotes shaking events.

Olds, Shelley

83

Process for slip casting textured tubular structures  

DOEpatents

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.

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

2002-01-01

84

Flow-induced vibrations-1987  

SciTech Connect

This book contains 20 selections. Some of the titles are: Acoustic resonance in heat exchanger tube bundles--Part 1. Physical nature of the phenomenon; Theoretical and experimental studies on heat exchanger U-bend tube bundle vibration characteristics; Experimental model analysis of metallic pipeline conveying fluid; Leakage flow-induced vibration of an eccentric tube-in-tube slip joint; and A study on the vibrations of pipelines caused by internal pulsating flows.

Au-Yang, M.K.; Chen, S.S.

1987-01-01

85

Slip asymmetry in the molecular crystal cyclotrimethylenetrinitramine  

NASA Astrophysics Data System (ADS)

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.

Mathew, N.; Picu, R. C.

2013-09-01

86

Slip System Activity During Cyclic Plasticity  

NASA Astrophysics Data System (ADS)

The present investigation discusses about the occurrence and activity of slip systems in low-cycle fatigue deformation of metastable austenite (fcc) at various total strain amplitudes (?? t) under ambient temperature, where the rate of deformation is kept constant. It has been found that with the increase in strain amplitude, the activity of the single slip system decreases and that of the multiple slip system increases.

Das, Arpan

2014-04-01

87

Learning to predict slip for ground robots  

NASA Technical Reports Server (NTRS)

In this paper we predict the amount of slip an exploration rover would experience using stereo imagery by learning from previous examples of traversing similar terrain. To do that, the information of terrain appearance and geometry regarding some location is correlated to the slip measured by the rover while this location is being traversed. This relationship is learned from previous experience, so slip can be predicted later at a distance from visual information only.

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

2006-01-01

88

Slip System Activity During Cyclic Plasticity  

NASA Astrophysics Data System (ADS)

The present investigation discusses about the occurrence and activity of slip systems in low-cycle fatigue deformation of metastable austenite (fcc) at various total strain amplitudes (? ? t) under ambient temperature, where the rate of deformation is kept constant. It has been found that with the increase in strain amplitude, the activity of the single slip system decreases and that of the multiple slip system increases.

Das, Arpan

2014-06-01

89

Episodic Tremor and Slip on a Frictional Interface with Critical Zero Weakening in Elastic Solid  

NASA Astrophysics Data System (ADS)

Non Volcanic Tremor (NVT) and related relatively weak and slow slip events, termed jointly Episodic Tremor and Slip (ETS), are observed below the seismogenic sections of numerous subduction zones and major strike-slip faults. These events have several distinguishing characteristics including moment-duration scaling relation with exponent less than 2, intermittency and flickering behavior, relatively small slip, high susceptibility for triggering, and temporal occurrence with numerous periodicities. Here we show with analytical and numerical results that a frictional fault in elastic solid with a strip below the seismogenic zone having critical zero weakening during slip provides a simple unified explanation for the diverse observed phenomena associated with ETS. The results imply that ETS have little to no predictive power on the occurrence of large events in the overriding seismogenic zone. Additional model predictions that should be tested with future high-resolution observations are fractal slip distributions and failure areas, potency/moment proportional to area and duration proportional to effective source radius (producing together the observed moment-duration scaling), discrete power law frequency-moment statistics with exponent 3/2 and exponential tapering, overall scale-invariant potency/moment time histories, and parabolic (or exponential) source time functions for event sizes measured by duration (or moment).

Ben-Zion, Y.

2010-12-01

90

Bulk Metallic Glasses Deform via Slip Avalanches.  

PubMed

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

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

2014-04-18

91

Bulk Metallic Glasses Deform via Slip Avalanches  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

92

Detailed joint structure in a geothermal reservoir from studies of induced microearthquake clusters  

Microsoft Academic Search

Microearthquake clusters form distinct, planar patterns within five study regions of a geothermal reservoir undergoing hydraulic fracturing at Fenton Hill, New Mexico. The patterns define individual, slipping joint surfaces of dimension 40â120 m, containing 80â150 events each. Sharp, straight edges truncate the clusters, apparently intersections with aseismic joints. Each edge orientation is consistent with an intersection between the active joint

W. Scott Phillips; Leigh S. House; Michael C. Fehler

1997-01-01

93

Episodic Tremor and Slip on the Cascadia Subduction Zone: The Chatter of Silent Slip  

Microsoft Academic Search

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor

Garry Rogers; Herb Dragert

2003-01-01

94

Seismic rehabilitation of beam–column joint using GFRP sheets  

Microsoft Academic Search

Techniques for upgrading reinforced concrete beam–column joints are proposed. The test specimens represent a typical joint that was built in accordance to pre-1970s’ codes. The objective of the rehabilitation is to upgrade the shear strength of these joints and reduce the potential for bond-slip of the bottom bars of the beam. Glass fibre-reinforced polymer (GFRP) sheets are wrapped around the

T El-Amoury; A Ghobarah

2002-01-01

95

Slip compensation for a Mars rover  

Microsoft Academic Search

A system that enables 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, compensate for slippage, and reach intended goals in high-slip environments. These components include: visual odometry, vehicle kinematics, a Kalman filter pose estimator, and a

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

2005-01-01

96

Slipping processes in residual badlands reliefs  

Microsoft Academic Search

We define slips as structures developed by more or less saturated colloidal suspension that slide down the walls of residual reliefs found in badlands. These suspensions seem to originate in the soils crowning gully reliefs and also from rainwater dripping onto the walls of poorly cemented sediments such as siltstone. We call this process slipping and the resulting morphologies represent

Jose Luis Díaz-Hernández; Jorge Yepes

2010-01-01

97

Dislocation Cross-slip Mechanisms in Aluminum  

NASA Astrophysics Data System (ADS)

We have systematically studied dislocation cross-slip in Al at zero temperature by atomistic simulations, focusing on the dependence of the transition paths and energy barriers on dislocation length and position. We find that for a short dislocation segment, the cross-slip follows the uniform Fleischer (FL) mechanism. For a longer dislocation segment, we have identified two different cross-slip mechanisms depending on the initial and final positions of the dislocation. If the initial and final positions are symmetric relative to the intersection of the primary and cross-slip planes, the dislocation cross-slips via the Friedel-Escaig (FE) mechanism. However, when the initial and final positions are asymmetric, the dislocation cross-slips via a combination of the FL and FE mechanisms. The leading partial folds over to the cross-slip plane first, forming a stair-rod dislocation at the intersection with which the trailing partial then merges via the FL mechanism. Afterwards, constrictions appear asymmetrically and move away from each other to complete the cross-slip via the FE mechanism.

Xiang, Yang; Jin, Congming; Lu, Gang

2012-02-01

98

Biomechanics of Slips in Older Adults.  

National Technical Information Service (NTIS)

Slip and fall accidents are among the leading generators of injuries in the workplace, especially among older adults. The aging dynamics of the work force have motivated the long-term goal of this proposed study, that is to reduce slip-precipitated falls ...

R. Cham

2009-01-01

99

STUDY ON EARTHQUAKE DAMAGE IN DUCTILE IRON PIPE JOINT  

NASA Astrophysics Data System (ADS)

In recent year, most of water pipe damages caused by earthquakes have been reported by pull out at joint. Ductile iron pipe are classified as mechanical type for earthquake-proof or non-earthquake-proof joint and slip-on type for non-e-proof joint. The earthquake proof joint never been damaged in the past earthquakes but the damage for another types of joint occurred frequently. Since the type of joint depends on the manufaction age and pipe diameter. Therefore, it could be estimated the relation between the damage rate and joint type. This paper focused on this issue. The resistance force against pull out at joint was clarified by the experiments and the results are discussed. Finally the earthquake adaptability for the different joint types is proposed.

Kumaki, Yoshihiro; Miyajima, Masakatsu

100

Effect of molecular structure on liquid slip  

NASA Astrophysics Data System (ADS)

Slip behavior of three liquids with distinct molecular shapes—linear (hexadecane), branched (pentaerythritol tetra), and a chain of rings (polyphenylether)—is studied using molecular dynamics simulation and reduced-order modeling. Slip at a liquid-solid interface is shown to be affected by the molecular structure of the liquid. A two-dimensional Frenkel-Kontorova model captures the fundamental structural features of the liquid molecules and gives insight into how molecules flex and slip along the surface. We formulate an approximation to the Peierls-Nabarro energy which incorporates both the position of liquid atoms relative to substrate atoms and molecular flexibility. We find that increased molecular flexibility can lead to reduced slip by allowing the liquid to conform epitaxially to the substrate with only a small energetic penalty. Liquid molecules which are less flexible can conform to the substrate only with greater expense of conformational energy, and so exhibit larger slip.

Vadakkepatt, Ajay; Dong, Yalin; Lichter, Seth; Martini, Ashlie

2011-12-01

101

Effect of molecular structure on liquid slip.  

PubMed

Slip behavior of three liquids with distinct molecular shapes--linear (hexadecane), branched (pentaerythritol tetra), and a chain of rings (polyphenylether)--is studied using molecular dynamics simulation and reduced-order modeling. Slip at a liquid-solid interface is shown to be affected by the molecular structure of the liquid. A two-dimensional Frenkel-Kontorova model captures the fundamental structural features of the liquid molecules and gives insight into how molecules flex and slip along the surface. We formulate an approximation to the Peierls-Nabarro energy which incorporates both the position of liquid atoms relative to substrate atoms and molecular flexibility. We find that increased molecular flexibility can lead to reduced slip by allowing the liquid to conform epitaxially to the substrate with only a small energetic penalty. Liquid molecules which are less flexible can conform to the substrate only with greater expense of conformational energy, and so exhibit larger slip. PMID:22304194

Vadakkepatt, Ajay; Dong, Yalin; Lichter, Seth; Martini, Ashlie

2011-12-01

102

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

PubMed

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 surface slip resistance. Peak COFU during weight acceptance was calculated and the available floor surface slip resistance was measured using the variable incidence tribometer (VIT). Separate logistic regression analyses identified that knowledge of the available slip resistance (as measured by the VIT) in combination with an individual's peak COFU allowed for greater accuracy in classifying slip outcomes (89.5%; p = 0.004), while knowledge of only the available slip resistance reduced the accuracy of categorization to 78.9% (p = 0.021). PMID:16803728

Burnfield, J M; Powers, C M

2006-08-15

103

Tidal modulation of slow slip in Cascadia  

NASA Astrophysics Data System (ADS)

Several studies have shown that the seismic tremor in episodic tremor and slip is tidally modulated, suggesting a sensitivity to the rather small tidal stresses. We address whether the slip rate in slow slip events is also tidally modulated by examining data from six borehole strainmeters in northwest Washington and southern Vancouver Island. We simultaneously fit data from multiple stations and from slow slip events occurring over a 3 year interval from January 2007 to June 2009, as we are unable to extract a meaningful signal from a single record. We find modulation of the strain rate with a 12.4 h period, that of the tide with the largest amplitude, that is significant at the 99% level. The amplitude of this modulation suggests that the slip rate during slow slip events oscillates, on average, 25% above and below its mean value during a tidal cycle. Tidal modulation estimates at three other periods are significant with more than 70% probability. The phase of maximum strain rate in the 12.4 h M2 period coincides with the phase of the maximum tremor rate taken from a catalog in an overlapping region. Comparison with a simple tidal loading model shows that the phase of maximum strain rate in the M2 period may occur at the maximum shear stress or up to 90° before it, depending on the location of slip in the subduction zone.

Hawthorne, Jessica C.; Rubin, Allan M.

2010-09-01

104

Maximum slip in earthquake fault zones, apparent stress, and stick-slip friction  

USGS Publications Warehouse

The maximum slip, observed or inferred, for a small patch within the larger fault zone of an earthquake is a remarkably well-constrained function of the seismic moment. A large set of maximum slips, mostly derived from slip models of major earthquakes, indicate that this parameter increases according to the cube root of the seismic moment. Consistent with this finding, neither the average slip rate for the patches of maximum slip nor the apparent stresses of earthquakes show any systematic dependence on seismic moment. Maximum average slip rates are several meters per second independent of moment and, for earthquakes in continental crustal settings, the apparent stress is limited to about 10 MPa. Results from stick-slip friction experiments in the laboratory, combined with information about the state of stress in the crust, can be used to predict, quite closely, the maximum slips and maximum average slip rates within the fault zones of major earthquakes as well as their apparent stresses. These findings suggest that stick-slip friction events observed in the laboratory and earthquakes in continental settings, even with large magnitudes, have similar rupture mechanisms.

McGarr, A.; Fletcher, J. B.

2003-01-01

105

Mechanisms for liquid slip at solid surfaces.  

PubMed

One of the oldest unresolved problems in fluid mechanics is the nature of liquid flow along solid surfaces. It is traditionally assumed that across the liquid-solid interface, liquid and solid speeds exactly match. However, recent observations document that on the molecular scale, liquids can slip relative to solids. We formulate a model in which the liquid dynamics are described by a stochastic differential-difference equation, related to the Frenkel-Kontorova equation. The model, in agreement with molecular dynamics simulations, reveals that slip occurs via two mechanisms: localized defect propagation and concurrent slip of large domains. Well-defined transitions occur between the two mechanisms. PMID:15447199

Lichter, Seth; Roxin, Alex; Mandre, Shreyas

2004-08-20

106

Frictional Dissipation in Stick-Slip Sliding  

NASA Astrophysics Data System (ADS)

The time variation of the frictional force between two surfaces, undergoing stick-slip sliding across a molecularly thin film of a confined model liquid, was examined at high time and force resolution, showing clearly that dissipation of energy occurs both during the slip, and at the instant of stick (via transfer of residual momentum). Detailed analysis indicates that, in marked contrast to earlier suggestions, of order 90% or more of the dissipation occurs by viscous heating of the confined shear-melted film during the slip, and only a small fraction of the energy is dissipated at the instant of stick.

Klein, Jacob

2007-02-01

107

Frictional dissipation in stick-slip sliding.  

PubMed

The time variation of the frictional force between two surfaces, undergoing stick-slip sliding across a molecularly thin film of a confined model liquid, was examined at high time and force resolution, showing clearly that dissipation of energy occurs both during the slip, and at the instant of stick (via transfer of residual momentum). Detailed analysis indicates that, in marked contrast to earlier suggestions, of order 90% or more of the dissipation occurs by viscous heating of the confined shear-melted film during the slip, and only a small fraction of the energy is dissipated at the instant of stick. PMID:17358875

Klein, Jacob

2007-02-01

108

Slow slip event at Kilauea Volcano  

USGS Publications Warehouse

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].

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

109

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

110

Suppression of strike-slip fault zones by preexisting crustal heterogeneities  

NASA Astrophysics Data System (ADS)

Although transform (strike-slip on land) faults are a defining feature of plate tectonics, plate boundary models show several regions where shearing is the primary regional deformation mechanism that completely lack or have underdeveloped strike-slip fault systems with respect to their slip rate. Regions that exhibit rapid toroidal (shearing) flow as indicated by GPS velocities, focal mechanisms, and/or neotectonic models but lack pervasive strike-slip faulting tend to possess common features that predate shearing, such as: (1) extensive fracturing perpendicular or sub-perpendicular to the shear plane (e.g., South Iceland Seismic Zone and Walker Lane, CA), and/or (2) regional cover of flood basalts or andesites containing columnar joints (e.g., Brothers Fault Zone, Oregon). We present a new plane-stress finite-strain analog model created to investigate the evolution of primary deformation zones in pure strike-slip fault systems where crustal heterogeneities emulating (1) and (2) exist prior to shear initiation. Experimental results indicate that, in comparison to systems with originally pristine surfaces, strike-slip fault systems containing preexisting structures develop more distributed geometries and that more than twice as much net offset is required for throughgoing strike-slip faulting to occur. These results provide new insight for kinematic interpretations of structural data from fault systems on Earth, Venus and other terrestrial bodies where crustal heterogeneities such as shear-plane perpendicular fractures and/or basaltic or andesitic flood basalts are present prior to shear initiation. Direct and independent confirmation of fault zone suppression could be provided through detailed geologic analyses of underdeveloped fault zones on Earth that exemplify the fault zone development observed in these experiments (e.g., Walker Lane, CA-NV).

Curren, I. S.; Bird, P.

2013-12-01

111

Interseismic slip rate of the northwestern Xianshuihe fault from InSAR data  

NASA Astrophysics Data System (ADS)

The Xianshuihe fault is a highly active strike-slip fault system near the eastern margin of the Tibetan plateau. We use a multi-interferogram method to construct a map of line-of-sight deformation rate due to interseismic strain accumulation on the northwestern Xianshuihe fault from a decade of SAR data acquired by the ERS-1/2 and Envisat satellites. The rate map shows a clear deformation gradient associated with the fault, but slightly offset to the northeast from the surface trace. Joint inversion of InSAR rate map and GPS data using Monte-Carlo method, we estimate a slip rate of 9-12 mm/yr with a locking depth of 3-6 km at the 90% confidence level. The slip rate agrees with the Holocene fault slip rate and the historical earthquakes. Our results also suggest no significant across-fault extension. In the future, InSAR data from both ascending and descending orbits may further constrain the 3-D fault slip rate on this fault.

Wang, H.; Wright, T. J.; Biggs, J.

2009-02-01

112

46 CFR 56.30-40 - Flexible pipe couplings of the compression or slip-on type.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Flexible pipe couplings of the compression or...Piping Joints § 56.30-40 Flexible pipe couplings of the compression or slip-on type. (a) Flexible pipe couplings of the...

2009-10-01

113

46 CFR 56.30-40 - Flexible pipe couplings of the compression or slip-on type.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Flexible pipe couplings of the compression or...Piping Joints § 56.30-40 Flexible pipe couplings of the compression or slip-on type. (a) Flexible pipe couplings of the...

2010-10-01

114

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), after slipped capital femoral epiphysis  

Microsoft Academic Search

ObjectiveThe aim of this study was to assess the glycosaminoglycan (GAG) content in hip joint cartilage in mature hips with a history of slipped capital femoral epiphysis (SCFE) using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC).

Christoph Zilkens; Falk Miese; Bernd Bittersohl; Marcus Jäger; Johannes Schultz; Arne Holstein; Young-jo Kim; Michael B. Millis; Tallal C. Mamisch; Rüdiger Krauspe

2011-01-01

115

Dipole Dependent Slip of Simple Liquids  

NASA Astrophysics Data System (ADS)

We study the slippage of various Newtonian liquids on alkylsilane coated glass surfaces using the colloidal probe atomic force microscopy technique. For small contact angle non-polar liquids, the slip length is found to decrease as a wetting transition is approached. By contrast, for large contact angle polar liquids the wettability no longer determines the slip behavior. Instead, we find that the slip length decreases with increasing dipole moment. For highly polar liquids a strong electrostatic repulsive force is also observed. These results strongly suggest that the dipole-dipole and dipole-image dipole interactions in the vicinity of surfaces structure the surface molecules which in turn influence the surface slip behavior. This research was supported by the Petroleum Research Fund, administered by the American Chemical Society, and by NSF through grant number DMR-0097119.

Law, Bruce M.; Cho, Jae-Hie J.; Rieutord, Francois

2004-03-01

116

Slip casting alumina with Na-CMC  

SciTech Connect

Many forming methods are in common use for engineering ceramics. Of these, slip casting is an ideal forming method because of its low cost, simplicity and flexibility, potential for uniform particle packing and suitability to the production of articles of intricate shape. Slip casting nonclay materials, such as alumina, requires the use of both a deflocculant and a binder. There are many commercially available deflocculants and binders that can be tested in alumina casting slips. However, determination of a suitable deflocculant/binder combination and quantification of the optimal additions of the deflocculant/binder pair can be time consuming. Certain deflocculants are capable of acting as binders. One such additive is sodium carboxymethylcellulose (Na-cmc), a cellulose ether. Na-cmc is a powerful binder. It is a member of the carbohydrate binder group--the binder group with the strongest binding power. It is capable of acting as a deflocculant in glazes and nonclay casting slips.

Ruys, A.J.; Sorrell, C.C. [Univ. of New South Wales, Sydney, New South Wales (Australia)

1996-11-01

117

Bone scintigraphy in slipped capital femoral epiphysis  

SciTech Connect

Tc-/sub 99m/ diphosphonate bone scans were performed on 11 children with slipped capital femoral epiphysis. On pinhole hip images, seven hips in seven patients had increased radionuclide uptake in the physis and adjacent proximal femoral metaphysis where the slip had occurred. Three hips in three patients had decreased radionuclide uptake in the femoral head on the side of the slipped epiphysis, indicating compromise of the femoral head blood supply. Three or more months following internal fixation, three children had scintigraphy that showed loss of the usual focal uptake in the physis and adjacent proximal femoral metaphysis. Bone scintigraphy in pediatric patients with slipped capital femoral epiphysis is valuable in defining the metabolic status of the femoral head. Absence of radiopharmaceutical uptake in the affected femoral head indicates that the femoral head is at risk for development of radiographic changes associated with aseptic necrosis.

Gelfand, M.J.; Strife, J.L.; Graham, E.J.; Crawford, A.H.

1983-12-01

118

Thin-film rupture for large slip  

Microsoft Academic Search

The rupture of thin liquid films on hydrophobic substrates, assuming large slip at the liquid-solid interface, is studied\\u000a using a recently developed strong slip lubrication model, it is shown that the rupture passes through up to three self-similar regimes with different dominant balances\\u000a and different scaling exponents. For one of these regimes the similarity is of second kind, and the

D. Peschka; A. Münch; B. Niethammer

2010-01-01

119

Slip at Fluid-Solid Interface  

Microsoft Academic Search

The `no-slip' is a fundamental assumption and generally-accepted boundary condition in rheology, tribology and fluid mechanics with strong experimental support. The violations of this condition, however, are widely recognized in many situations, especially in the flow of non-Newtonian fluids. Wall slip could lead to large errors and flow instabilities, such as sharkskin formation and spurt flow, and hence complicates the

Taha Sochi

2011-01-01

120

Seven big strike-slip earthquakes  

Microsoft Academic Search

We examine seven large (Mw > 7) strike-slip earthquakes that occurred since the beginning of ERS 1 and 2 missions. We invert GPS observations and InSAR interferograms and azimuth offsets for coseismic slip distributions. We explore two refinements to the traditional least-squares inversion technique with roughness constraints. First, we diverge from the usual definition of ``roughness'' as the average roughness

R. B. Lohman; M. Simons; M. E. Pritchard

2003-01-01

121

On Stokes slip flow through a transversely wavy channel  

Microsoft Academic Search

The Stokes flow through a wavy or corrugated channel with surface slip is studied. The correct Navier's partial slip condition is applied and perturbation solutions about the small amplitude to channel width ratio are obtained. As in Stokes slip flow over a sphere, the resistance is not zero even when slip is infinite. The resistance (due to the interaction of

C. Y. Wang

2011-01-01

122

On the imaging of slip boundaries using 3D elastography  

Microsoft Academic Search

Slip elastography is a new branch of elastography which incorporates shear strain imaging and force estimation, with a view to detecting and characterizing slip boundaries between tumors and their surroundings. This paper introduces the principles of slip elastography. It is hypothesized that apparent shear strains may arise due to shear motion across a slip boundary. This is investigated through FEM

Leo J. Garcia; Christopher Uff; Jérémie Fromageau; Jeffrey C. Bamber

2009-01-01

123

Are Surface Displacements Representative of Slip at Seismogenic Depths? Implications for Geologic Slip Rate Studies  

Microsoft Academic Search

It has long been recognized that during large strike-slip earthquakes surface displacements are in many instances smaller than displacements at depth. This is often interpreted to imply that a significant proportion of the slip at depth is accommodated by distributed deformation near the surface. We hypothesize that the degree to which deformation is localized at the surface is fundamentally controlled

B. Haravitch; J. F. Dolan; Y. Klinger

2009-01-01

124

Slip band propagation and slip vector transition in B2 FeAl single crystals  

SciTech Connect

At the peak temperature, 823 K, of the yield strength anomaly of B2 FeAl, slip band propagation and slip vector transition were investigated using Fe-39 mol% Al single crystals. The single crystal oriented along a compression axis close to the [{bar 1}23] direction showed serrated flow during work-hardening at small strains (< 2%). Coarse slip bands propagate in the single crystal specimens, like Lueders band propagation in polycrystals, in the initial strain range. The slip vector was identified by TEM to be parallel to {l_angle}111{r_angle} in the early stage of strain corresponding to yielding. Beyond plastic strains of about 3%, serrations disappeared and significant work-softening occurred. The slip vector responsible for the later stage of deformation was observed to be {l_angle}100{r_angle}. That is, the slip vector changes from {l_angle}111{r_angle} to {l_angle}100{r_angle} as the plastic strain increases. Because the density of {l_angle}111{r_angle} superdislocations is found to be very low after the slip transition, glide decomposition of {l_angle}111{r_angle} superdislocations is believed to be the primary source mechanism for {l_angle}100{r_angle} dislocations. The slip band propagation in B2 single crystals is discussed in comparison with that of other intermetallic single-crystalline materials.

Yoshimi, K.; Hanada, S. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research] [Tohoku Univ., Sendai (Japan). Inst. for Materials Research; Yoo, M.H. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.] [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1998-10-09

125

Digital slip frequency generator and method for determining the desired slip frequency  

DOEpatents

The output frequency of an electric power generator is kept constant with variable rotor speed by automatic adjustment of the excitation slip frequency. The invention features a digital slip frequency generator which provides sine and cosine waveforms from a look-up table, which are combined with real and reactive power output of the power generator.

Klein, Frederick F. (Monroeville, PA) [Monroeville, PA

1989-01-01

126

Joint Problems  

MedlinePLUS

... ankles and toes. Other types of arthritis include gout or pseudogout. Sometimes, there is a mechanical problem ... for more information on osteoarthritis, rheumatoid arthritis and gout. How Common are Joint Problems? Osteoarthritis, which affects ...

127

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

Microsoft Academic Search

Discovery of pseudotachylytes from exhumed accretionary complexes indicates that frictional melting occurred along illite-rich, argillite-derived slip zones during subduction earthquakes. We conducted high-velocity friction experiments on argillite at a slip rate of 1.13 m\\/s and normal stresses of 2.67–13.33 MPa. Experiments show slip weakening followed by slip strengthening. Slip weakening is associated with the formation and shearing of low-viscosity melt

Kohtaro Ujiie; Akito Tsutsumi; Yuri Fialko; Haruka Yamaguchi

2009-01-01

128

Macromolecular Liquids Slip Over Solid Surfaces: Experimental Studies of the Slip Length  

NASA Astrophysics Data System (ADS)

We present a novel method to asses the slip length and viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyze dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes [1]. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity of films with thicknesses between 50 nm and 230 nm and temperatures above the glass transition. We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and 10 microns on DTS covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements [2]. [1] R. Fetzer, K. Jacobs, A. Muench, B. Wagner, T.P. Witelski, Phys. Rev. Lett. 95, 127801 (2005) [2] R. Fetzer, K. Jacobs, M. Rauscher (to be published)

Jacobs, Karin; Fetzer, Renate

2006-03-01

129

Hairpin river loops and slip-sense inversion on southeast Asian strike-slip faults  

NASA Astrophysics Data System (ADS)

In the Golden Triangle region of southeast Asia (northern Thailand, Laos and Burma, southern Yunnan), the Mekong, Salween, and neighboring rivers show hairpin geometries where they cross active strike-slip faults. Restoration of young, left-lateral offsets of these rivers leaves residual right-lateral bends of many kilometers. We interpret these hairpins as evidence of late Cenozoic slip-sense inversion on these faults, about 5 to 20 Ma. Near the Red River fault, stress field and slip-sense inversion occurred ca. 5 Ma. This implies that the present course of these large rivers has existed for at least several million years. Pliocene Quaternary slip rates, possibly on the order of 1 mm/yr, are inferred on each of the strike-slip faults of the Golden Triangle.

Lacassin, Robin; Replumaz, Anne; Hervé Leloup, P.

1998-08-01

130

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

131

Active and recent strike-slip tectonics  

NASA Astrophysics Data System (ADS)

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.

Nur, Amos; Boccaletti, Mario

132

Slip in viscous contact-line movement  

NASA Astrophysics Data System (ADS)

The typical continuum fluid dynamics formulation cannot be used to model the spreading of a liquid on a solid because a stress singularity prevents contact-line motion. It is well known that this situation can be remedied by introducing a slip. We perform Stokes-flow simulations with slip and compare these with experiments. In the experiment, liquid (squalane) is forced through two parallel sapphire plates (roughness 0.6nm), and the meniscus shape and its speed are measured. The slip-length for this liquid/solid pair has been measured previously in an independent experiment absent of contact lines (T. Schmatko et. al. PRL 94, 244501). The same geometry is used in a boundary integral method simulation, accurate to within a few molecular diameters in the vicinity of the contact-line. The slip-length in the simulations can be varied such that the meniscus shape matches the experiment. Preliminary results suggest this slip-length is an order of magnitude lower than that reported by Schmatko.

van Lengerich, Henrik; Steen, Paul; Breuer, Kenneth

2011-11-01

133

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

NASA Astrophysics Data System (ADS)

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.

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

134

Evolution of slip surface roughness through shear  

NASA Astrophysics Data System (ADS)

significant part of displacement in fault zones occurs along discrete shear surfaces. The evolution of fault surface topography is studied here in direct shear laboratory experiments. Matching tensile fracture surfaces were sheared under imposed constant normal stress and sliding velocity. The roughness evolution was analyzed using measurements of surface topography before and after slip. We show that shearing reduces the initial surface roughness at all measurement scales. At all wavelengths, the roughness ratio between initial and final roughness increases as a function of the slip distance. For a given test, the roughness ratio increases with wavelength up to a few millimeters, beyond which the ratio becomes wavelength independent. At this region the roughness measured after slip follows a power law similar to that of the initial tensile fracture surface. We interpret this geometrical evolution as a consequence of the deformation stage of interlocked asperities which is followed by shear-induced dilation.

Davidesko, Guy; Sagy, Amir; Hatzor, Yossef H.

2014-03-01

135

Seven big strike-slip earthquakes  

NASA Astrophysics Data System (ADS)

We examine seven large (Mw > 7) strike-slip earthquakes that occurred since the beginning of ERS 1 and 2 missions. We invert GPS observations and InSAR interferograms and azimuth offsets for coseismic slip distributions. We explore two refinements to the traditional least-squares inversion technique with roughness constraints. First, we diverge from the usual definition of ``roughness'' as the average roughness over the entire fault plane, and allow ``variable smoothing'' constraints. Variable smoothing allows our inversion to select models that are more complex in regions that are well-resolved by the data, while still damping regions that are poorly resolved. Second, we choose our smoothing parameters using the jR_i criterion. The jR_i criterion draws on the theory behind cross-validation and the bootstrap method. We examine the theoretical basis behind such methods and use an analytical approximation technique for linear problems. We provide maps of model variance and spatial averaging scale over the fault plane, to explicitly show which features in our slip models are robust. We examine the 1992 Landers (CA), 1995 Sakhalin (Russia), 1995 Kobe (Japan), 1997 Ardekul (Iran), 1997 Manyi (Tibet), 1999 Hector Mine (CA), and 2001 Kunlun (Tibet) earthquakes. We compare features of the slip distributions such as the depth distribution of slip, the inferred magnitude and the degree of heterogeneity of slip over the fault plane, as resolved by the available InSAR and GPS data. We end with a brief description of the data coverage required for future earthquakes of similar size if we want to infer some of the above quantities to within a given confidence interval. We describe both the number of InSAR scenes and the distribution of GPS points that would be required, based on theoretical treatments of the fault plane/data point geometry using the jR_i method.

Lohman, R. B.; Simons, M.; Pritchard, M. E.

2003-12-01

136

Momentum compaction and phase slip factor  

SciTech Connect

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.

Ng, K.Y.; /Fermilab

2010-10-01

137

Slipping magnetic reconnection in coronal loops.  

PubMed

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

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

138

Slipping processes in residual badlands reliefs  

NASA Astrophysics Data System (ADS)

We define slips as structures developed by more or less saturated colloidal suspension that slide down the walls of residual reliefs found in badlands. These suspensions seem to originate in the soils crowning gully reliefs and also from rainwater dripping onto the walls of poorly cemented sediments such as siltstone. We call this process slipping and the resulting morphologies represent a group of minor badlands forms, often linked to piping and fluting. Slipping occurs according to the following sequence of forms: 1. Mud droplets. These are irregular linear structures caused by mud droplets sliding down sub-vertical walls. The droplet is usually found at the end of a small channel. These morphologies represent the course of the sliding droplets that become fossilized and not the impact of the droplets on the sediment. 2. Slips sensu stricto. These are uninterrupted surface structures covering sub-vertical walls to a greater or lesser extent. The thickness of this type of covering varies from a few millimetres to 5cm. The inner structure of the slips consists of small laminas (» 100mm) and on the exterior they often present drip channels. A special case of these forms is butterfly structures, which appear in isolation, with repetitive patterns and the appearance of a winged insect stuck to the wall. 3. Pseudo-stalactites. These are free-standing conical regrowths with some similarity to stalactites in a karst cave. They occur when slips grow to over 5cm thick. The growth of these forms is similar to that of slips, with external superposition of fine, concentric layers with no central pore. A variety of these pseudo-stalactites are nodulous stalactites whose genesis is unknown. In this context, we should mention the existence of occasional stalagmites. In other cases, curtains of pseudo-stalactites can be found where these patterns are repeated finely. A more evolved stage of this form is the coalescence of pseudo-stalactites, representing a massive advance of this process. Pseudo-stalactites are normally found as vertical, but occasionally they lean, indicating movement of unstable blocks. The process can present recycling when some of the forms described become detached and fall. This is more likely on poorly sheltered surfaces, exposed to wind and the direct impact of rain and frost. All forms of slips suggests that these morphologies depend on the varying characteristics of the colloidal suspensions causing them, and constitute intermediate stages in the retention of sediments from erosion, which are very different to the alluvial sediments stored in the drainage network.

Díaz-Hernández, Jose Luis; Yepes, Jorge

2010-05-01

139

The mechanics of stick-slip  

USGS Publications Warehouse

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.

Byerlee, J. D.

1970-01-01

140

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

PubMed Central

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.

Du, Shuang; Gao, Yang

2012-01-01

141

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

PubMed

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

Du, Shuang; Gao, Yang

2012-01-01

142

Geodetically derived fault slip distribution model for the May, 11th 2011 Lorca earthquake (SE, Spain)  

NASA Astrophysics Data System (ADS)

The Alhama de Murcia Fault (AMF) is a compound multisegmented right-lateral to reverse fault system. The AMF is one the longest faults in the Eastern Betics Shear zone (Southeastern Spain). In the last decades its seismogenic potential has been evaluated and earthquake maximum magnitudes were forecast based on paleoseismic and dating data. On May 11th, 2011 a moderate (Mw 5.1) earthquake shook the region, causing 9 casualties and severe damages in Lorca city (Murcia region). The reported location of the aftershocks sequence did not follow any particular trend; furthermore in-situ geology surveys did not identify any fault slip related ground deformation. To contribute to a better seismic hazard assessment, we need to locate and, if possible, characterize the fault-slip distribution that generated the earthquake. In this work, we detected small but significant ground deformation in the epicentral area by using geodetic (GPS and satellite radar interferometry) data. Geodetic data was processed by using a stack of differential radar interferometry (corrected for a known subsidence contribution and estimating their error budget), daily GPS estimated coordinates and high-rate 1-Hz GPS data. We jointly inverted the detected static coseismic displacements (a GPS station and two ENVISAT interferograms from different tracks) for the fault plane geometry parameters by using a rectangular dislocation model embedded in a homogeneous elastic half-space. The best-fitting fault plane follows closely the geologically derived AMF geometry (NE-SW strike trend and dipping ~60-70o to NW). Later, the obtained model geometry was extended and divided into patches to allow for a detailed analysis of the fault slip distribution pattern. Slip distribution indicates that slip occurred in a single patch with reverse and right-lateral motion (with peak fault slip magnitude of ~9 cm). However, the modelling results also indicate that the fault slip was shallower along the centre and southwest of the city of Lorca. The shallower character of the slip probably caused the relative intense ground acceleration recorded at the Lorca city (0.4g) and increased the building damages. We show that the Lorca earthquake was generated by a simple segment (6-8 km long) slightly dipping to the NW of the AMF system. This study also represents the first modern geodetically observed ground deformation signature due to seismic activity in the Iberian Peninsula.

Gonzalez, P. J.; Tiampo, K. F.; Palano, M.; Cannavò, F.; Fernandez, J.

2011-12-01

143

Slip casting and nitridation of silicon powder  

NASA Astrophysics Data System (ADS)

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.

Seiko, Y.

1985-03-01

144

Slip-Cast Coating of Alumina Crucibles.  

National Technical Information Service (NTIS)

The development of a process for coating alumina crucibles with MgO protective coat in a two-step slip casting operation is described. The best milling conditions for the alumina used were set ball milling for 24 hr. MgO had to be calcined at 1200 exp 0 C...

N. A. Haroun M. A. A. El-Masry

1980-01-01

145

Deformation patters above intrusive complexes in strike-slip settings  

NASA Astrophysics Data System (ADS)

Long-lived intrusions below volcanic complexes are weak, ductile zones in the crust. In volcanic areas with strike-slip deformation pull-apart complexes are often associated with volcanoes, especially calderas. The Masaya-Las Sierras volcano in Nicaragua is a basaltic caldera complex situated in a developing pull-apart (Managua Graben). The pull-apart faults are responsible for highly damaging earthquakes (Managua 1931, 68, 72). We raise the hypothesis that pull-apart and caldera intrusive system are interrelated and that joint surveillance of faults and volcano could provide the best monitoring strategy. To test relationships between intrusive complex and tectonics we have run a series of ‘sand-box’ analogue models. Displacement is created by a motor on a basal discontinuity and computer-controlled. The models have a lower ductile crust (silicone layer), an upper brittle crust (sand and plaster), and an intrusion made of silicone or varying density and viscosity. Experiments show that a pull apart always forms around a ductile intrusion, irrespective of its density, however that a non-ductile intrusive complex has no significant influence. Whatever the shape of the intrusion, the fault pattern forms a typical rhombohedral pull-apart shape. Fault patterns spaying out from the models resemble closely the Managua fault pattern. With large displacements two zones of thrusting were observed in the system. Such deformation is not present at Masaya, but may be at other calderas with more active strike-slip activity. We provide one possible example in the Atacama, N Chile.

Girard, G.; van Wyk de Vries, B.

2003-04-01

146

Development of Slip-Ring Materials for Space Use,  

National Technical Information Service (NTIS)

Three-axis geostationary satellites employ slip rings to transmit control signals and electric power between the satellite body and the sun-tracking solar paddles. Slip rings used in space must maintain their lubricative and conductive characteristics rel...

M. Watanabe M. Harima J. Nakagawa M. Suzuki M. Nishimura

1987-01-01

147

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

Microsoft Academic Search

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

S. A. Kattenhorn; S. T. Marshall

2003-01-01

148

Influence of fault slip rate on shear-induced permeability  

NASA Astrophysics Data System (ADS)

We measured permeability in sandstone and granite sheared at slip rates from 10-4 to 1.3 m/s under low-normal stress at confining pressures up to 120 MPa. As the slip rate increased, the permeability of Berea sandstone decreased by an order of magnitude, whereas that of Indian sandstone and Aji granite increased by 3 orders of magnitude at high slip rates. A fine-grained gouge layer of thickness developed during slip, and the wear rate was increased abruptly at high slip rates. Microcracks and mesoscale fractures formed at slip rates above 0.13 m/s. Numerical modeling showed that the slip surface temperature increased by several hundred degrees for slip velocities above 0.13 m/s and exceeded the ?-? phase transition temperature of quartz at 1.3 m/s. Both the temperature rise and the temperature gradient at the slip surface were high at fast slip rates. We attributed reduced permeability after slip in porous sandstone to the low-permeability gouge layer. An abrupt permeability increase in low-permeability rocks at high slip rates was caused by heat-induced cracks. An increase in the rate of wear of gouge with increasing slip velocity was caused by frictional heating that reduced the rock strength. The host-rock permeability that separated reductions and increases in permeability was about 10-16 m2 at 10 MPa effective pressure. Our results suggest that abrupt increases in shear stress during slip in a low-permeability fault zone caused by thermal cracking, which may decrease the total slip displacement. The abrupt permeability increase at high slip rates in low-permeability rocks agrees with hydrogeochemical phenomena observed after earthquakes.

Tanikawa, Wataru; Sakaguchi, Masumi; Tadai, Osamu; Hirose, Takehiro

2010-07-01

149

Influence of fault slip rate on shear-induced permeability  

NASA Astrophysics Data System (ADS)

We measured permeability in sandstone and granite sheared at slip rates from 0.1 to 1300 m/s under low normal stress at confining pressures up to 120 MPa. As slip rate increased, the permeability of Berea sandstone (5*10-14 m2 of permeability at 10 MPa effective pressure) decreased by an order of magnitude, whereas that of Indian sandstone (10-16 m2) and Aji granite (10-19 m2) increased by three orders of magnitude at high slip rates. A fine-grained gouge layer of thickness proportional to slip rate developed during slip. Microcracks and mesoscale fractures formed at slip rates above 0.13 m/s. Numerical modeling showed that the slip surface temperature increased by several hundred degrees for slip velocities above 0.13 m/s and exceeded the ?-? phase transition temperature of quartz at 1.3 m/s. Both temperature rise and the temperature gradient at the slip surface were high at fast slip rates. We attributed reduced permeability after slip in porous sandstone to the low permeability gouge layer. An abrupt permeability increase in low permeability rocks at high slip rates was caused by heat-induced cracks. An increase in the rate of wear of gouge with increasing slip velocity was caused by frictional heating that reduced rock strength. The host-rock permeability that separated reductions and increases of permeability was around 10-16 m2 at 10 MPa effective pressure. Our results suggest that abrupt increases of shear stress during slip in a low permeability fault zone cause thermal cracks, which decrease slip displacement. The abrupt permeability increase at high slip rates in low permeability rocks agrees with hydrogeochemical phenomena observed after earthquakes.

Tanikawa, Wataru; Hirose, Takehiro; Sakaguchi, Masumi; Tadai, Osamu

2010-05-01

150

Influence of slip rheology on pressure casting of alumina  

Microsoft Academic Search

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

R. Moreno; A. Salomoni; I. Stamenkovic

1997-01-01

151

A Mechanism of Slip-Band Propagation in Whiskers.  

National Technical Information Service (NTIS)

A possible mechanism of propagation of slip is by cross-slip as suggested by Brenner, and it is the purpose of this note to show that the presence of one or more axial screw dislocations may aid the propagation of slip in a different way. (Author)

M. N. Shetty

1968-01-01

152

Local Bond-Slip Relationship for FRP Reinforcement in Concrete  

Microsoft Academic Search

The objective of this paper is to define a rigorous numerical method to calibrate parameters of a given local bond-slip relationship using experimental results of pullout tests, taking into account the distribution of the slip and bond shear stress throughout the bar. The proposed method involves finding parameters of a given bond-slip relationship, such that results of pullout tests can

Francesco Focacci; Antonio Nanni; Charles E. Bakis

2000-01-01

153

Cycle slipping in discrete phase-controlled system  

Microsoft Academic Search

This paper considers cycle slipping of discrete phase-controlled system with periodic nonlinearity. The number of slipped cycles is an important characteristic of such nonlinear system. Based on Yakubovich-Kalman Lemma which establishes the equivalence between frequency domain inequalities (FDIs) and linear matrix inequalities (LMIs), the conditions of estimating the number of slipped cycles are derived. Then dynamic output feedback controller is

Pingli Lu; Ying Yang; Lin Huang

2006-01-01

154

Pivoting and slip in an angular contact bearing  

NASA Technical Reports Server (NTRS)

Pivoting slips are calculated for the ball-race and ball-ball contacts in a retainerless bearing. The calculation is kinematic, ignoring all inertial loadings. Pure spin and uniform precession of the balls are considered. Pivoting slip magnitudes are compared with several other kinds of slip which were previously reported in an R4 size bearing.

Kingsbury, E.

1983-01-01

155

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

NASA Astrophysics Data System (ADS)

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.

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

156

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

PubMed

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 trials. Three increasing levels of prior knowledge were used: deceived (unaware of the slippery surface), aware (20% chance of a slippery surface, but no prior slip experience) and experienced (aware with prior slip experience). Available friction was measured using a drag sled and a variable incidence tribometer. Of 620 low-friction trials, 124 generated slips greater than 27mm. The proportion of slips, the slip distance and the required friction (taken from the control trial immediately before a low-friction trial) generally decreased with increasing levels of prior knowledge. These adaptations were accommodated by logistically regressing slip outcome (yes/no) against the normalized friction (available friction minus required friction) rather than against available friction alone. The regressions showed that subject awareness biased the slip probability curve toward a lower slip risk for a given normalized friction, but that the subsequent addition of slip experience generated a slip risk curve that was not significantly different from that of deceived (and presumably unprepared) subjects. These findings suggest that data to validate a tribometer's ability to predict the risk of slipping (but not falling) can be acquired from subjects with prior slip experience. PMID:16171996

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

2006-08-01

157

Joint pain  

Microsoft Academic Search

Joint pain may result from traumas or repeated microtraumas, as in sports injuries. Pain in osteoarthritis starts before any\\u000a objective finding. It has been demonstrated that in the first stages of this disease, pain is due to intraosseous venous engorgement\\u000a for the earlier thickening of the cortical bone under the articular cartilage. The mechanisms of inflammatory pain are more\\u000a complex

Massimo Zoppi; Elisabetta Beneforti

1999-01-01

158

Persistent currents in quantum phase slip rings  

NASA Astrophysics Data System (ADS)

We investigate the effect of interacting quantum phase slips on persistent current and its fluctuations in ultrathin superconducting nanowires and nanorings pierced by the external magnetic flux. We derive the effective action for these systems and map the original problem onto an effective sine-Gordon theory on torus. We evaluate both the flux-dependent persistent current and the critical radius of the ring beyond which this current gets exponentially suppressed by quantum fluctuations. We also analyze fluctuations of persistent current caused by quantum phase slips. At low temperatures, the supercurrent noise spectrum has the form of coherent peaks which can be tuned by the magnetic flux. Experimental observation of these peaks can directly demonstrate the existence of plasma modes in superconducting nanorings.

Semenov, Andrew G.; Zaikin, Andrei D.

2013-08-01

159

Smectite-illite transition during coseismic slip  

NASA Astrophysics Data System (ADS)

Few evidences for coseismic slip events are preserved in natural fault rocks except pseudotachylytes showing a clear evidence of melting caused by frictional shear at high slip rates [e.g., Spray, 1987; Tsutsumi and Shimamoto, 1997; Hirose and Shimamoto, 2005]. Higher maturity of vitrinite of coal fragments is observed in the fault cores recovered from the Nankai accretionary prism [Sakaguchi eta al., 2011], and also in the friction experiments sheared at seismic slip rates [Kitamura et al., 2012], implying that local heating is caused by frictional shear during earthquakes. Another possible evidence for coseismic slip is illitization of smectite clay along faults observed in the present and ancient accretionary prisms [Yamaguchi et al., 2011; Kameda et al., 2013]. Kameda et al. [2013] have estimated the fault activity using the kinetics of smectite-illite transition, which is determined in the studies on long-term diagenetic processes of smectite-illite transition and may not be appropriate for the short-tem reaction caused by frictional heating associated with coseismic slip. Here we report on high-speed friction experiments on synthetic smectite-quartz mixtures. The goals of our experiments are: (1) to reproduce the illitization of smectite clay (Na-montmorillonite) during coseismic shear and (2) to obtain better kinetic parameters to estimate the fault activity of coseismic slip. The friction experiments were conducted on the rotary-shear apparatus at AIST. One gram of the synthetic gouge of smectite-quartz (70:30 wt.%) mixture was sheared at slip velocity of 1.3 m/s, normal stress of 1 MPa, and up to displacement of 55 m. Because cation exchange between sodium ion in smectite and potassium ion in fluid is required for the illitization, we used gouge samples dampened with two different pore fluid media: (1) 1 mol/L aqueous solution of potassium chloride (KCl) and (2) pure water. Friction coefficient of the gouge sheared with potassium rich fluid is 0.45 at peak and 0.12 at steady state, and approximately two times greater than friction coefficient of the gouge sheared with pure water (0.27 at peak and 0.05 at steady state). Pore fluid chemistry largely affects the frictional strength of gouge and thus probably temperature evolution within the gouge. X-ray diffraction analysis of the post-experiment gouges with ethylene glycol treatment indicate illite generation in the gouge sheared with potassium-rich fluid; i.e., smectite is partly transformed to illite by the frictional heating. The gouge sheared with pure water, on the other hand, shows no evidence for illite generation. We will present more experimental results and derive interrelationships between the degree of the illitization, slip velocity, shear displacement, frictional strength, temperature, and concentrations of the potassium ion in pore fluid.

Takahashi, M.; Kitajima, H.

2013-12-01

160

Earthquake slip between dissimilar poroelastic materials  

NASA Astrophysics Data System (ADS)

A mismatch of elastic properties across a fault induces normal stress changes during spatially nonuniform in-plane slip. Recently, Rudnicki and Rice showed that similar effects follow from a mismatch of poroelastic properties (e.g., permeability) within fluid-saturated fringes of damaged material along the fault walls; in this case, it is pore pressure on the slip plane and hence effective normal stress that is altered during slip. The sign of both changes can be either positive or negative, and they need not agree. Both signs reverse when rupture propagates in the opposite direction. When both elastic and poroelastic properties are discontinuous across the fault, steady sliding at a constant friction coefficient, f, is unstable for arbitrarily small f if the elastic mismatch permits the existence of a generalized Rayleigh wave. Spontaneous earthquake rupture simulations on regularized slip-weakening faults confirm that the two effects have comparable magnitudes and that the sign of the effective normal stress change cannot always be predicted solely from the contrast in elastic properties across the fault. For opposing effects, the sign of effective normal stress change reverses from that predicted by the poroelastic mismatch to that predicted by the elastic mismatch as the rupture accelerates, provided that the wave speed contrast exceeds about 5-10% (the precise value depends on the poroelastic contrast and Skempton's coefficient). For faults separating more elastically similar materials, there exists a minimum poroelastic contrast above which the poroelastic effect always determines the sign of the effective normal stress change, no matter the rupture speed.

Dunham, Eric M.; Rice, James R.

2008-09-01

161

Cover slip external cavity diode laser.  

PubMed

A 671 nm diode laser with a mode-hop-free tuning range of 40 GHz is described. This long tuning range is achieved by simultaneously ramping the external cavity length with the laser injection current. The laser output pointing remains fixed, independent of its frequency because of the cover slip cavity design. This system is simple, economical, robust, and easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium atom beam experiments. PMID:17979464

Carr, Adra V; Sechrest, Yancey H; Waitukaitis, Scott R; Perreault, John D; Lonij, Vincent P A; Cronin, Alexander D

2007-10-01

162

On the mechanism of cross slip in Ni3AI  

NASA Astrophysics Data System (ADS)

The mechanical properties of Ll2 intermetallic alloys have been previously described by models based on the assumption that cube cross slip is the rate-limiting step. In this study, it was demonstrated that the cube cross-slip event must be reversible under a change in loading direction. This observation allows the cross-slip models to remain consistent with cyclic deformation data. Additionally, this observation was used as a critical test of the available cross-slip models. It was demonstrated that the rate-limiting step cannot be a total cross-slip event, in which both ?/2(110) superpartial dislocations cross slip to the cube plane. Conversely, the limited cross-slip event proposed by Paidar, Pope, and Vitek (PPV) was demonstrated to be consistent with the reversibility constraint. This lends additional experimental support to the PPV model.

Milligan, Walter W.; Antolovich, Stephen D.

1989-12-01

163

Compilation of Slip in Last Earthquake Data for High-Slip Rate Faults in California for Input into Slip Dependent Rupture Forecast  

NASA Astrophysics Data System (ADS)

Slip in the last earthquake along a fault, in conjunction with the application of appropriate recurrence models, can be used to estimate the timing and size of future ground-rupturing earthquakes. Surface slip measurements are relatively easy to acquire along highly active faults because offsets from the last event are usually well preserved by geomorphic features in the landscape. We present a comprehensive database of slip measurements for high slip rate strike-slip and dip-slip faults in California for input into the slip-dependent 2011 Uniform California Earthquake Rupture Forecast (UCERF 3). Our database includes historic, paleoseismic, and geomorphic data on the slip in the last event and multi-event offsets. Faults were prioritized by highest slip rates and longest time since the last event relative to average recurrence interval. Slip rate, timing of the last event, and recurrence interval were obtained from past reports by the Working Group on California Earthquake Probabilities, unless more recently published data were available. A literature search determined the availability of offset data for the highest priority faults. We contacted authors of published slip studies to ascertain whether additional data exist in unpublished archives, gray literature, or publications in preparation. The lack of consistency in existing schemes to rate offset quality led us to develop a new semi-quantitative method to asses feature quality and tectonic quality for new and existing data. Recent analyses of newly available, high-resolution LiDAR topography for micro-geomorphic offsets have substantially increased the number of slip measurements available for our compilation. For faults with LiDAR coverage, but limited, poor, or unavailable offset data, we identified reaches with a high potential to preserve geomorphic offsets and calculated slip measurements. The methodology for our geomorphic analyses has been developed and implemented successfully in recent studies along the central San Jacinto Fault and 1857 earthquake reach of the San Andreas Fault. Last, we compiled data collected from our literature search and LiDAR analysis into a geodatabase. Our database contains multiple measurements for the same features using different techniques, making it a powerful tool to test the repeatability of slip measurements. Our compilation reveals that despite local variation, slip values tend to cluster around a reach averaged mean, and slip can be similar at a point over multiple events.

Arrowsmith, R.; Madden, C.; Haddad, D. E.; Salisbury, J. B.; Weldon, R. J.

2011-12-01

164

Quantum phase slips in superconducting nanowires  

NASA Astrophysics Data System (ADS)

In this thesis we present the results of an experimental study of the superconducting transitions of ultrathin nanowires. In order to reliably fabricate homogeneous nanowires, a novel technique was developed. By depositing 4--5 nm of amorphous Mo79Ge21 on carbon nanotubes or ropes, which act as mechanical substrates, we are able to routinely fabricate wires about 10 nm in diameter. More than 20 nanowires have been fabricated and measured, with lengths ranging from 150 nm to 1mum, and nominal widths ranging from 10 to 22 nm. Our resistance-temperature measurements of these nanowires display superconducting transitions which broaden with decreasing cross-sectional areas; the thinnest wires' resistance stayed almost constant down to 1.5K. Since resistance arises from phase slippage in the superconducting order parameter Psi, such resistive transitions can be explained by a combination of the activation of phase slips through a free energy barrier via thermal excitation close to TC, and via macroscopic quantum tunneling at lower temperatures. Because the phase slip rates increase exponentially with decreasing cross-sectional areas of the wires, superconductivity in a thin wire is suppressed at low temperatures by the proliferation of quantum phase slips. This conclusion is based on the quantitative agreement between the data and the predictions made by a microscopic theory developed by Golubev and Zaikin.

Lau, Chun Ning

165

Coseismic slip on shallow décollement megathrusts  

NASA Astrophysics Data System (ADS)

Many regions of plate convergence are underlain by décollement megathrusts, which form the base of both accretionary wedges and fold-and-thrust belts. These faults may extend laterally for hundreds or thousands of kilometers, and downdip for tens to hundreds of kilometers. Traditionally, estimates of seismic hazard have assumed that these faults slip aseismically, without releasing significant seismic energy, under the belief that they are too weak to build accumulate large stresses. However, in several recent cases, these faults have been shown to slip in large, discrete events, resulting in hazardous groundshaking and/or tsunamis (e.g., 2011 Tohoku-Oki earthquake, Japan; 2010 Mentawai earthquake, Indonesia; 1999 Chi-Chi earthquake, Taiwan). We present a series of fifteen examples, both on-land and offshore, demonstrating that many shallow dé- collements are capable of producing large, coseismic slip events that rupture to the toes of the systems. Some of these events are associated with ruptures that initiate down-dip, while others are limited to the frontal, shallow portion of the wedge, illustrating that the frontal portion can initiate rupture as well as participate in ruptures that initiated elsewhere. We suggest that this behavior is not limited to the examples described here, but rather is common to many (perhaps most) accretionary wedges and fold-and-thrust belts. Although many earthquakes in subduction zones have been interpreted to have no slip at the tip of the accretionary prism, this interpretation is typically driven by model assumptions, rather than the data. We suggest that in addition to the examples provided here, there may be many other examples of similar earthquakes, where existing data cannot constrain slip at the toe. We do not characterize the regions and events described here as unusual, as they encompass a wide range of settings. This study indicates that there is an urgent need to reevaluate seismic and tsunami hazard in fold-and-thrust belts and subduction zones around the world, allowing for the possibility of shallow décollement rupture.

Hubbard, Judith; Barbot, Sylvain; Hill, Emma M.; Tapponnier, Paul

2014-05-01

166

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

NASA Astrophysics Data System (ADS)

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.

McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

2014-05-01

167

Progressive slippage after pinning for slipped capital femoral epiphysis.  

PubMed

The authors retrospectively reviewed seven cases of progressive slipped capital femoral epiphysis after screw fixation. All seven patients initially presented with chronic symptoms, and five had an acute exacerbation of symptoms with the appearance of an acute-on-chronic slip. Of the other two, one had obvious motion at the proximal femoral physis and the other had increased symptoms but did not have an obvious acute slip radiographically. All underwent percutaneous screw fixation. In four patients a single screw was placed, and in three patients two screws were placed. No patient became symptom-free after surgery. Slip progression was noted on average 5 months after treatment. Radiographs in all patients revealed an increase in slip severity and loss of screw purchase in the femoral neck while fixation in the proximal femoral epiphysis remained secure. One patient had hypothyroidism and another Cushing disease, both diagnosed after the slipped epiphysis. Slips occurring in children with underlying endocrinopathies, and unstable slips in children with a history of antecedent knee or hip pain (commonly called an acute-on-chronic slip) may be susceptible to screw fixation failure. In such patients, close radiographic follow-up, particularly in the presence of continued symptoms, is required to document slip progression and fixation failure as soon as possible. PMID:11856939

Sanders, James O; Smith, William J; Stanley, Earl A; Bueche, Matthew J; Karol, Lori A; Chambers, Henry G

2002-01-01

168

The Alhama de Murcia fault slip-rate: first constraints from updated slip-rates  

NASA Astrophysics Data System (ADS)

The NNW-SSE shortening between Eurasian and African plates takes place at rate of 4-6 mm/yr and is mostly absorbed, in the Iberian part, by the EBSZ (SE Spain). The Alhama de Murcia fault (AMF) is one of the faults in this system. It is generally considered that the AMF has a slow slip rate (on the order of 0.1 mm/yr, although associated to high uncertainties), but new geologic and geodetic investigations suggest that the slip rate could be an order of magnitude higher, more concordant with the slip rate of the Carboneras fault, which is located in the SW termination of the EBSZ. The evidence of higher slip rates for the AMF includes: 1) a slip rate of 1.5 mm/yr obtained with GPS measurements between the northern block of the AMF and the southern block of the Palomares fault (however, this value would be the sum of the slip-rates of both EBSZ faults although Palomares shows less morphological expression); 2) first estimations of lateral offsets in buried channels in paleoseismic 3D trenches, where an upper Pleistocene to Holocene paleochannel is offset up to 10 m; and 3) different age (from middle Pleistocene to Holocene) surface morphologies (channels and terraces) are offset between 10 and 100 m. U/Th on pedogenic carbonates together with other classical dating techniques is used to constrain the age of these offsets. To be the higher slip rate confirmed, the seismic hazard of the AMF, that struck Lorca with a catastrophic earthquake in 2011 with 9 fatalities (Mw5.2), should be thoroughly revised. Previous paleoseismic studies in the study area suggest that the AMF is capable of producing earthquakes of up to Mw 7. High slip rates would imply shorter recurrence periods associated with the fault and therefore, the time-dependent seismic hazard in the area would drastically be enlarged as the seismic catalogue does not show any of such large earthquakes in the last 500 yr.

Ferrater, Marta; Maria, Ortuño; Masana, Eulàlia; Khazaradze, Giorgi; Echeverría, Anna; Pallàs, Raimon; García-Meléndez, Eduardo; Martínez-Díaz, José; Baize, Stéphane; Perea, Héctor; Cunha, Pedro P.; Rockwell, Tom

2014-05-01

169

The effect of sliding velocity on the mechanical response of an artificial joint in Topopah Spring Member tuff; Yucca Mountain Site Characterization Project  

SciTech Connect

A smooth artificial joint in Topopah Spring Member tuff was sheared at constant normal stress at velocities from 0 to 100 {mu}m/s to determine the velocity-dependence of shear strength. Two different initial conditions were used: (1) unprimed -- the joint had been shear stress-free since last application of normal stress, and before renewed shear loading; and (2) primed -- the joint had undergone a slip history after application of normal stress, but before the current shear loading. Observed steady-state rate effects were found to be about 3 times lager than for some other silicate rocks. These different initial conditions affected the character of the stress-slip curve immediately after the onset of slip. Priming the joint causes a peak in the stress-slip response followed by a transient decay to the steady-state stress, i.e., slip weakening. Slide-hold-slide tests exhibit time-dependent strengthening. When the joint was subjected to constant shear stress, no slip was observed; that is, joint creep did not occur. One set of rate data was collected from a surface submerged in tap water, the friction was higher for this surface, but the rate sensitivity was the same as that for surfaces tested in the air-dry condition.

Olsson, W.A.

1994-04-01

170

Complicated Recurrence of Slip Events on a Uniform Circular Asperity  

NASA Astrophysics Data System (ADS)

Numerical simulation of repeated occurrence of slip events on a fault patch (asperity) is conducted to understand the mechanism of irregularity of the events. Seismic and geodetic observations indicate that episodic seismic/aseismic slip events repeatedly occur at almost the same area. For instance, magnitude of about 4.8 earthquakes had repeatedly occurred at intervals of 4.7 to 6.7 years off Kamaishi, northern Honshu, Japan. Quasi-periodic recurrence of episodic aseismic slip events (slow earthquakes) was found at the Nankai subduction zone, southwestern Japan, the Cascadia subduction zone, North America, etc. The recurrence intervals and magnitudes of slip events in each sequence are not constant, but some variability exists. Some researchers suggested that the variation in aseismic slip rate around a patch of slip events causes variation of loading rate. This results in variation of recurrence intervals. In the present study, we focus on irregularity of recurrence of slip events that originates from dynamics of fault slip. A two-dimensional planar fault in an infinite elastic medium is considered. The fault is uniformly shear loaded at a constant rate, and frictional stress acting on the fault is assumed to obey a rate- and state-dependent friction (RSF) law. A circular patch of radius r with velocity-weakening frictional property is embedded on a fault with velocity-strengthening frictional property elsewhere. A numerical simulation is conducted by varying the characteristic slip distance L of the RSF law. The critical radius rc for occurrence of unstable slip can be defined, and rc is proportional to L. When r >> rc, seismic slip events (earthquakes) repeatedly occur at a constant time interval. When r is a little larger than rc, recurrence of slip events becomes complex. We observe a period-2 cycle of slip events, where large and small events alternately occur. The cycle becomes more complex as r approaches rc and finally aperiodic (chaotic) slip pattern occurs. During the increase of slip complexity, a period-doubling sequence is observed. An iteration map of recurrence intervals of slip events is examined by taking a plot of Ti versus Ti-1, where Ti denotes the time interval between the ith and (i+1)th slip events. The iteration map is expressed by a simple curve, suggestive of predictability of the occurrence time of the next event from the previous time interval. To understand the cause of the variation of slip events, the distributions of shear stress on the fault before the slip events are examined. We observe a large variation of the shear stress distribution within the velocity-weakening region, which is generated by the preceding slip event and aseismic sliding during an interseismic period. To compare the simulation result of sequence of slip events on a velocity-weakening patch embedded in velocity-strengthening region, a numerical simulation of slip on a velocity-weakening patch enclosed by unbreakable barrier. In this case, no complex recurrence of slip events is observed. When r > rc, seismic slip events repeatedly occur at a constant interval. On the other hand, stable sliding occurs when r < rc. This result indicates that the complicated slip behavior for a velocity-weakening patch embedded in velocity-strengthening region comes from the interaction between the velocity-weakening and velocity-strengthening regions.

Kato, N.

2012-12-01

171

GREEN REACTION CHEMISTRIES PERFORMED IN THE SPINNING TUBE-IN-TUBE (STT) REACTOR  

EPA Science Inventory

The U. S. Environmental Protection Agency (USEPA) and Kreido Laboratories have established a Cooperative Research and Development Agreement (CRADA) collaboration, to develop and commercialize green and sustainable chemistries in the area of industrial chemical synthesis. Utilizi...

172

PROCESS INTENSIFIED GREEN REACTION CHEMISTRIES PERFORMED IN THE SPINNING TUBE-IN-TUBE (STT®) REACTOR  

EPA Science Inventory

The U. S. Environmental Protection Agency (USEPA) and Kreido Laboratories have established a Cooperative Research and Development Agreement (CRADA) collaboration, to develop and commercialize green and sustainable chemistries in the area of industrial chemical synthesis. Utilizi...

173

Organic Synthesis in a Spinning Tube-in-Tube (STT¢) Reactor  

EPA Science Inventory

Continuous-flow reactors have been designed to minimize and potentially overcome the limitations of heat and mass transfer that are encountered in chemical reactors and further experienced upon scale up of a reaction. With process intensification, optimization of the reaction i...

174

Tsunami Modeling to Validate Slip Models of the 2007 M w 8.0 Pisco Earthquake, Central Peru  

NASA Astrophysics Data System (ADS)

Following the 2007, August 15th, M w 8.0, Pisco earthquake in central Peru, Sladen et al. (J Geophys Res 115: B02405, 2010) have derived several slip models of this event. They inverted teleseismic data together with geodetic (InSAR) measurements to look for the co-seismic slip distribution on the fault plane, considering those data sets separately or jointly. But how close to the real slip distribution are those inverted slip models? To answer this crucial question, the authors generated some tsunami records based on their slip models and compared them to DART buoys, tsunami records, and available runup data. Such an approach requires a robust and accurate tsunami model (non-linear, dispersive, accurate bathymetry and topography, etc.) otherwise the differences between the data and the model may be attributed to the slip models themselves, though they arise from an incomplete tsunami simulation. The accuracy of a numerical tsunami simulation strongly depends, among others, on two important constraints: (i) A fine computational grid (and thus the bathymetry and topography data sets used) which is not always available, unfortunately, and (ii) a realistic tsunami propagation model including dispersion. Here, we extend Sladen's work using newly available data, namely a tide gauge record at Callao (Lima harbor) and the Chilean DART buoy record, while considering a complete set of runup data along with a more realistic tsunami numerical that accounts for dispersion, and also considering a fine-resolution computational grid, which is essential. Through these accurate numerical simulations we infer that the InSAR-based model is in better agreement with the tsunami data, studying the case of the Pisco earthquake indicating that geodetic data seems essential to recover the final co-seismic slip distribution on the rupture plane. Slip models based on teleseismic data are unable to describe the observed tsunami, suggesting that a significant amount of co-seismic slip may have been aseismic. Finally, we compute the runup distribution along the central part of the Peruvian coast to better understand the wave amplification/attenuation processes of the tsunami generated by the Pisco earthquake.

Ioualalen, M.; Perfettini, H.; Condo, S. Yauri; Jimenez, C.; Tavera, H.

2013-03-01

175

Fixed recurrence and slip models better predict earthquake behavior than the time- and slip-predictable models: 1. Repeating earthquakes  

NASA Astrophysics Data System (ADS)

The behavior of individual events in repeating earthquake sequences in California, Taiwan and Japan is better predicted by a model with fixed inter-event time or fixed slip than it is by the time- and slip-predictable models for earthquake occurrence. Given that repeating earthquakes are highly regular in both inter-event time and seismic moment, the time- and slip-predictable models seem ideally suited to explain their behavior. Taken together with evidence from the companion manuscript that shows similar results for laboratory experiments we conclude that the short-term predictions of the time- and slip-predictable models should be rejected in favor of earthquake models that assume either fixed slip or fixed recurrence interval. This implies that the elastic rebound model underlying the time- and slip-predictable models offers no additional value in describing earthquake behavior in an event-to-event sense, but its value in a long-term sense cannot be determined. These models likely fail because they rely on assumptions that oversimplify the earthquake cycle. We note that the time and slip of these events is predicted quite well by fixed slip and fixed recurrence models, so in some sense they are time- and slip-predictable. While fixed recurrence and slip models better predict repeating earthquake behavior than the time- and slip-predictable models, we observe a correlation between slip and the preceding recurrence time for many repeating earthquake sequences in Parkfield, California. This correlation is not found in other regions, and the sequences with the correlative slip-predictable behavior are not distinguishable from nearby earthquake sequences that do not exhibit this behavior.

Rubinstein, Justin L.; Ellsworth, William L.; Chen, Kate H.; Uchida, Naoki

2012-02-01

176

Fixed recurrence and slip models better predict earthquake behavior than the time- and slip-predictable models 1: repeating earthquakes  

USGS Publications Warehouse

The behavior of individual events in repeating earthquake sequences in California, Taiwan and Japan is better predicted by a model with fixed inter-event time or fixed slip than it is by the time- and slip-predictable models for earthquake occurrence. Given that repeating earthquakes are highly regular in both inter-event time and seismic moment, the time- and slip-predictable models seem ideally suited to explain their behavior. Taken together with evidence from the companion manuscript that shows similar results for laboratory experiments we conclude that the short-term predictions of the time- and slip-predictable models should be rejected in favor of earthquake models that assume either fixed slip or fixed recurrence interval. This implies that the elastic rebound model underlying the time- and slip-predictable models offers no additional value in describing earthquake behavior in an event-to-event sense, but its value in a long-term sense cannot be determined. These models likely fail because they rely on assumptions that oversimplify the earthquake cycle. We note that the time and slip of these events is predicted quite well by fixed slip and fixed recurrence models, so in some sense they are time- and slip-predictable. While fixed recurrence and slip models better predict repeating earthquake behavior than the time- and slip-predictable models, we observe a correlation between slip and the preceding recurrence time for many repeating earthquake sequences in Parkfield, California. This correlation is not found in other regions, and the sequences with the correlative slip-predictable behavior are not distinguishable from nearby earthquake sequences that do not exhibit this behavior.

Rubinstein, Justin L.; Ellsworth, William L.; Chen, Kate Huihsuan; Uchida, Naoki

2012-01-01

177

Slip stacking experiments at Fermilab main injector  

SciTech Connect

In order to achieve an increase in proton intensity, Fermilab Main Injector will use a stacking process called ''slip stacking''. The intensity will be doubled by injecting one train of bunches at a slightly lower energy, another at a slightly higher energy, then bringing them together for the final capture. Beam studies have started for this process and we have already verified that, at least for a low beam intensity, the stacking procedure works as expected. For high intensity operation, development work of the feedback and feedforward systems is under way.

Kiyomi Koba et al.

2003-06-02

178

Comparison of Joint Modeling Approaches Including Eulerian Sliding Interfaces  

SciTech Connect

Accurate representation of discontinuities such as joints and faults is a key ingredient for high fidelity modeling of shock propagation in geologic media. The following study was done to improve treatment of discontinuities (joints) in the Eulerian hydrocode GEODYN (Lomov and Liu 2005). Lagrangian methods with conforming meshes and explicit inclusion of joints in the geologic model are well suited for such an analysis. Unfortunately, current meshing tools are unable to automatically generate adequate hexahedral meshes for large numbers of irregular polyhedra. Another concern is that joint stiffness in such explicit computations requires significantly reduced time steps, with negative implications for both the efficiency and quality of the numerical solution. An alternative approach is to use non-conforming meshes and embed joint information into regular computational elements. However, once slip displacement on the joints become comparable to the zone size, Lagrangian (even non-conforming) meshes could suffer from tangling and decreased time step problems. The use of non-conforming meshes in an Eulerian solver may alleviate these difficulties and provide a viable numerical approach for modeling the effects of faults on the dynamic response of geologic materials. We studied shock propagation in jointed/faulted media using a Lagrangian and two Eulerian approaches. To investigate the accuracy of this joint treatment the GEODYN calculations have been compared with results from the Lagrangian code GEODYN-L which uses an explicit treatment of joints via common plane contact. We explore two approaches to joint treatment in the code, one for joints with finite thickness and the other for tight joints. In all cases the sliding interfaces are tracked explicitly without homogenization or blending the joint and block response into an average response. In general, rock joints will introduce an increase in normal compliance in addition to a reduction in shear strength. In the present work we consider the limiting case of stiff discontinuities that only affect the shear strength of the material.

Lomov, I; Antoun, T; Vorobiev, O

2009-12-16

179

Distribution of slip at the northern Sumatran fault system  

Microsoft Academic Search

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+\\/-3mm\\/yr at

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

2000-01-01

180

Slip rate gradients along the eastern Kunlun fault  

Microsoft Academic Search

Whether strike-slip fault systems in Eurasia accomplish eastward extrusion of Tibetan crust and lithosphere depends largely on the kinematics of deformation at the fault tip. Here we present new slip rate determinations using millennial-scale geomorphic markers from sites along the easternmost segment of the Kunlun fault in north central Tibet. This fault system represents one of the major strike-slip faults

Eric Kirby; Nathan Harkins; Erqi Wang; Xuhua Shi; Chun Fan; Douglas Burbank

2007-01-01

181

In Situ Pinning for Slipped Capital Femoral Epiphysis  

Microsoft Academic Search

We reviewed retrospectively 28 hips of 25 patients (22 boys and 3 girls) after in situ pinning for slipped capital femoral\\u000a epiphysis. The mean follow-up period was 5 years (range, 1.5–17). The mean age at surgery was 12.1 years (range, 10–14). Twenty-four\\u000a hips were stable slips and 4 hips were unstable. Fourteen hips were mild slips (lateral head-shaft angle less

Satoshi Iida; Yoshiyuki Shinada

182

On non-linear flows with slip boundary condition  

Microsoft Academic Search

The assumption that a fluid adheres to a solid boundary (‘no-slip’ boundary condition) is one of the central tenets of the Navier-Stokes theory. However, there are situations wherein this assumption does not hold. In this communication we examine the effects of slip at the wall when an Oldroyd 6-constant fluid is considered in a channel. The slip assumed depends on

T. Hayat; Masood Khan; M. Ayub

2005-01-01

183

Investigating the origins of observed variability of slow slip events with fault slip simulations  

NASA Astrophysics Data System (ADS)

Slow slip events (SSEs) in subduction zones around the world exhibit a wide range of recurrence intervals, durations, and spatial extents. In some regions, most notably Cascadia, distinct along-strike segmentation of these SSE characteristics have been observed. Yet the temporal extent of the SSE record is insufficient to determine whether along-strike variation in segmentation of SSEs persists beyond human time-scales. Here we employ the earthquake simulator RSQSim to model a simple, planar megathrust, which consists of seismogenic, slow slip, and continuous creep sections. The slow slip section is segmented to explore potential causes of along-strike variability in recurrence intervals, durations, and spatial extent, by varying parameters such as the effective normal stress, frictional properties, slip rates, and fault geometry. RSQSim enables simulations of long histories of SSEs over all orders of magnitude to allow for robust characterization of the variation in parameters. Preliminary results suggest even small variations in these parameters have a significant effect on observable characteristics of SSEs, which may illuminate the primary controls on along-strike variability and help establish a framework for understanding SSEs worldwide.

Watkins, W. D.; Colella, H.; Brudzinski, M. R.; Dieterich, J. H.; Richards-Dinger, K. B.

2013-12-01

184

Sugioka's Modified Hungria-Kramer intertrochanteric osteotomy in the treatment of severe slipped capital femoral epiphysis.  

PubMed

From May 1990 to November 1997, 24 cases of severe slipped capital femoral epiphysis were treated by an osteotomy that is a modification of the Hungria-Kramer intertrochanteric osteotomy proposed by Sugioka (Hungria-Kramer-Sugioka osteotomy or HKS osteotomy). The degree of displacement as seen on the frog-leg lateral radiograph of the proximal femur was measured according to the deviation of the longitudinal axis of the epiphysis from the center line of the neck (Fish classification). All hips were considered as grade III and underwent HKS osteotomy. Sugioka's radiographic study (true AP view with the limb internally rotated until the patella is perpendicular to the x-ray beam, and lateral view with the hip in 90 degrees flexion and 45 degrees abduction) was performed before surgery to show that the real direction of the slip was posterior in relation to the neck. Clinical results were assessed according to Merle-D'Aubigné and Postel system modified by Charnley (hip score system that takes into consideration pain, gait, and joint motion). Roentgenographic results were considered good if none of the following was present: joint space decreased by more than 2 mm (chondrolysis), avascular necrosis of the femoral head, neck-shaft angle of less than 120 degrees, nonunion at the osteotomy site, and a epiphyseal plate still open. Follow-up varied from 31 to 120 months (average 65.1 months). PMID:15958893

Fujiki, Edison N; Kuwajima, Sergio S; Honda, Emerson K; Milani, Carlo; Porto, Luiz Carlos K; Chikude, Takeshi; Fukushima, Walter Y; Ono, Nelson K

2005-01-01

185

Estimating Fault Slip Rates and Deformation at Complex Strike-Slip Plate Boundaries  

NASA Astrophysics Data System (ADS)

Modeling GPS velocity fields in seismically active regions worldwide indicates deformation can be efficiently and usefully described as relative motions among elastic, fault-bounded crustal blocks. These models are providing hundreds of new decadal fault slip rate estimates that can be compared with the (much smaller) independent Holocene (<10 ka) to late Quaternary (<125 ka) rates obtained by geological methods. Updated comparisons show general agreement but a subset of apparently significant outliers. Some of these outliers have been discussed previously and attributed either to a temporal change in slip rate or systematic error in one of the estimates. Here we focus particularly on recent GPS and geologic results from southern California and discuss criteria for assessing the differing rates. In southern California (and elsewhere), subjective choices of block geometry are unavoidable and introduce significant uncertainties in model formulation and in the resultant GPS fault slip rate estimates. To facilitate comparison between GPS and geologic results in southern California we use the SCEC Community Fault Model (CFM) and geologic slip rates tabulated in the 2008 Uniform California Earthquake Rupture Forecast (UCERF2) report as starting points for identifying the most important faults and specifying the block geometry. We then apply this geometry in an inversion of the SCEC Crustal Motion Model (CMM4) GPS velocity field to estimate block motions and intra-block fault slip rates and compare our results with previous work. Here we use 4 criteria to evaluate GPS/geologic slip rate differences. First: Is there even-handed evaluation of random and systematic errors? ‘Random error' is sometimes subjectively estimated and its statistical properties are unknown or idealized. Differences between ~equally likely block models introduces a systematic error into GPS rate estimates that is difficult to assess and seldom discussed. Difficulties in constraining the true initiation date of offset of geomorphic markers by faulting can introduce uncertainties much larger than quoted random errors. Second: Are rate estimates obtained by more than one geodetic or geologic method? For example, agreement between GPS and InSAR slip rate estimates on the Altyn Tagh and Haiyuan faults of Tibet make the geodetic estimates more reliable. Similarly, dating of multiple offset markers of differing age across these faults supports the consistency of the geologic rate estimates. Third: Is proposed rate change mechanism consistent with examples of changes in style and rate of deformation preserved in the geologic record? For example, temporal evolution of the multi-stranded San Andreas system during the past 5-10 Ma (Powell & Weldon 1992; Graymer et al. 2002) indicates activation and deactivation of different faults within the system accompanied by consequent changes in fault slip rate and/or creation of new crustal blocks. Fourth: Is there a quantitative analysis of mechanism proposed to explain rate change? Candidate mechanisms meriting quantitative analysis include (1) changes in frictional resistance of faults and creation of new fractures due to progressive rotation of irregularly shaped blocks, (2) episodic subduction of buoyant lithosphere, and (3) changes in the plate geometry (and so the forces acting) at major continent/ocean plate boundaries (e.g. Late Cenozoic migration of Mendocino triple junction off California). In most parts of southern California—for example, north of the San Andreas Big Bend and SE of Los Angeles--our block geometry closely resembles that assumed in previous studies (McCaffrey 2005 JGR; Meade & Hager 2005 JGR; Becker et al. 2005 GJI). In these regions GPS slip rates can be reliably estimated and values for individual faults generally agree from one study to another and are also consistent with geologic estimates. However, there is no consensus on block geometry in the Transverse Ranges, Los Angeles Basin and Central Mojave Desert, where CFM faults are densely distributed, UCERF2 slip rates on sever

Thatcher, Wayne; Murray-Moraleda, Jessica

2010-05-01

186

A treatment algorithm for stable slipped capital femoral epiphysis deformity.  

PubMed

The authors' current experience in the surgical treatment strategy of stable slipped capital femoral epiphysis deformities was reviewed. From this, a treatment algorithm was developed that could be utilized as a guide in the evaluation and treatment of future patients with slipped capital femoral epiphysis. The clinical parameters of patients' histories of symptoms, physical examinations, and radiographic assessments of slip severity were used in formulating the algorithm. The intent was to prepare a comprehensive algorithm providing necessary alternate treatment pathways for the variable slip deformity in accordance with the surgical experience/expertise of the treating surgeon. PMID:23764781

Schoenecker, Perry L; Gordon, J Eric; Luhmann, Scott J; Dobbs, Matthew B; Keeler, Kathryn A; Clohisy, John C

2013-01-01

187

Micromechanics of slip bands on a free surface  

NASA Technical Reports Server (NTRS)

A micromechanics analysis for the formation and propagation of slip bands on the free surface of a polycrystal under monotonic loading is presented. For the growth of slip bands, the analysis satisfies the conditions of both equilibrium and displacement continuity, as well as the relation between slip and the resolved shear stress throughout the polycrystal. Numerical calculations show how the microstress field causes the concentration of plastic deformation in discrete sliding bands and give results which are in good qualitative agreement with known slip band observations on aluminum single crystals.

Lin, S. R.; Lin, T. H.

1976-01-01

188

Inverting measurements of surface slip on the Superstition Hills fault  

USGS Publications Warehouse

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

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

1989-01-01

189

Aseismic Slip and the Nisqually Earthquake  

NASA Astrophysics Data System (ADS)

Continuous Global Positioning System (GPS) stations in the Pacific Northwest move northeast with respect to the North American plate as a result of coupling along the subducting Juan de Fuca plate. In early 2001 GPS stations from southern Puget Sound to northern Oregon reversed this northeast direction of motion for several weeks. The reversed motion shares some of the spatial and temporal signatures of aseismic creep events (or silent earthquakes) previously reported farther north along the Cascadia plate interface [1,2], although the periodic recurrence observed farther north has not been established here. The strongest aseismic motion was detected southwest of Seattle at the GPS stations SATS and RPT1. On February 28, 2001, during this period of aseismic slip, the Mw 6.8 Nisqually earthquake ruptured a normal fault within the Juan de Fuca plate. The rupture occurred at some 50 km depth; its epicenter lies between these two stations. The aseismic motion preceeding the earthquake is consistent with slip on the plate boundary. The displacements from the Nisqually earthquake itself are in good agreement with calculations using fault parameters from the inversion of seismic data. 1) Herb Dragert,, Kelin Wang, and Thomas S. James, Science, 292, 1525-1528, 2001 2) M. Meghan Miller, Tim Melbourne, Daniel J. Johnson, and William Q. Sumner, Science, 295, 2423, 2002

Sumner, W. Q.; Miller, M. M.

2002-12-01

190

How is a stick slip rupture initiated?  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

191

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

PubMed

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

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

2014-01-22

192

Jointness: A Selected Bibliography.  

National Technical Information Service (NTIS)

JDEIS is the Joint Doctrine, Education and Training Community Electronic Information System. It encompasses a searchable Joint Doctrine Database, a Joint Education section that includes the JPME Prospective Research Topics Database, as well as award-winni...

L. Garder

2010-01-01

193

Joint Advanced Warfighting School.  

National Technical Information Service (NTIS)

When the United States employs military power, it does so as a joint force. The cornerstone for effective joint force employment remains Service competency, but truly effective Service warfighters must think, plan and fight jointly. The key to developing ...

J. M. Davis K. C. Bowen L. W. Schonenberg

2003-01-01

194

Understanding Joint Warfighting Experiments.  

National Technical Information Service (NTIS)

In October 1998 the United States Joint Forces Command (USJFCOM) established a Joint Warfighting Experimentation program to support Joint Concept Development. Experimentation is the unique scientific method for establishing whether hypothesized concepts a...

R. A. Kass

2001-01-01

195

Arthritis: Metacarpophalangeal (MP) Joint  

MedlinePLUS

... Z Hand Anatomy Find a Hand Surgeon Arthritis - MP Joint Email to a friend * required fields From * ... drift (See Figure 2). When arthritis affects the MP joints, the condition is called MP joint arthritis. ...

196

Fixed recurrence and slip models better predict earthquake behavior than the time- and slip-predictable models: 2. Laboratory earthquakes  

NASA Astrophysics Data System (ADS)

The behavior of individual stick-slip events observed in three different laboratory experimental configurations is better explained by a "memoryless" earthquake model with fixed inter-event time or fixed slip than it is by the time- and slip-predictable models for earthquake occurrence. We make similar findings in the companion manuscript for the behavior of natural repeating earthquakes. Taken together, these results allow us to conclude that the predictions of a characteristic earthquake model that assumes either fixed slip or fixed recurrence interval should be preferred to the predictions of the time- and slip-predictable models for all earthquakes. Given that the fixed slip and recurrence models are the preferred models for all of the experiments we examine, we infer that in an event-to-event sense the elastic rebound model underlying the time- and slip-predictable models does not explain earthquake behavior. This does not indicate that the elastic rebound model should be rejected in a long-term-sense, but it should be rejected for short-term predictions. The time- and slip-predictable models likely offer worse predictions of earthquake behavior because they rely on assumptions that are too simple to explain the behavior of earthquakes. Specifically, the time-predictable model assumes a constant failure threshold and the slip-predictable model assumes that there is a constant minimum stress. There is experimental and field evidence that these assumptions are not valid for all earthquakes.

Rubinstein, Justin L.; Ellsworth, William L.; Beeler, Nicholas M.; Kilgore, Brian D.; Lockner, David A.; Savage, Heather M.

2012-02-01

197

Modeling of the effects of propagating thrust slip on pore pressures and implications for monitoring  

Microsoft Academic Search

Recent observations at subduction zones and other environments have brought attention to the variety of slip processes along fault zones, including aseismic slip, slow slip, and very-low-frequency seismicity. Pore pressure records from monitoring wells have the potential to provide information on the nature of these slip processes. In this study, an analytical solution for strain due to fault slip is

E. J. Screaton; S. Ge

2007-01-01

198

Surface fault slip associated with the 2004 Parkfield, California, earthquake  

USGS Publications Warehouse

Surface fracturing occurred along the San Andreas fault, the subparallel Southwest Fracture Zone, and six secondary faults in association with the 28 September 2004 (M 6.0) Parkfield earthquake. Fractures formed discontinuous breaks along a 32-km-long stretch of the San Andreas fault. Sense of slip was right lateral; only locally was there a minor (1-11 mm) vertical component of slip. Right-lateral slip in the first few weeks after the event, early in its afterslip period, ranged from 1 to 44 mm. Our observations in the weeks following the earthquake indicated that the highest slip values are in the Middle Mountain area, northwest of the mainshock epicenter (creepmeter measurements indicate a similar distribution of slip). Surface slip along the San Andreas fault developed soon after the mainshock; field checks in the area near Parkfield and about 5 km to the southeast indicated that surface slip developed more than 1 hr but generally less than 1 day after the event. Slip along the Southwest Fracture Zone developed coseismically and extended about 8 km. Sense of slip was right lateral; locally there was a minor to moderate (1-29 mm) vertical component of slip. Right-lateral slip ranged from 1 to 41 mm. Surface slip along secondary faults was right lateral; the right-lateral component of slip ranged from 3 to 5 mm. Surface slip in the 1966 and 2004 events occurred along both the San Andreas fault and the Southwest Fracture Zone. In 1966 the length of ground breakage along the San Andreas fault extended 5 km longer than that mapped in 2004. In contrast, the length of ground breakage along the Southwest Fracture Zone was the same in both events, yet the surface fractures were more continuous in 2004. Surface slip on secondary faults in 2004 indicated previously unmapped structural connections between the San Andreas fault and the Southwest Fracture Zone, further revealing aspects of the structural setting and fault interactions in the Parkfield area.

Rymer, M. J.; Tinsley, III, J. C.; Treiman, J. A.; Arrowsmith, J. R.; Ciahan, K. B.; Rosinski, A. M.; Bryant, W. A.; Snyder, H. A.; Fuis, G. S.; Toke, N. A.; Bawden, G. W.

2006-01-01

199

Seismic and aseismic slip on the central Peru megathrust.  

PubMed

Slip on a subduction megathrust can be seismic or aseismic, with the two modes of slip complementing each other in time and space to accommodate the long-term plate motions. Although slip is almost purely aseismic at depths greater than about 40 km, heterogeneous surface strain suggests that both modes of slip occur at shallower depths, with aseismic slip resulting from steady or transient creep in the interseismic and postseismic periods. Thus, active faults seem to comprise areas that slip mostly during earthquakes, and areas that mostly slip aseismically. The size, location and frequency of earthquakes that a megathrust can generate thus depend on where and when aseismic creep is taking place, and what fraction of the long-term slip rate it accounts for. Here we address this issue by focusing on the central Peru megathrust. We show that the Pisco earthquake, with moment magnitude M(w) = 8.0, ruptured two asperities within a patch that had remained locked in the interseismic period, and triggered aseismic frictional afterslip on two adjacent patches. The most prominent patch of afterslip coincides with the subducting Nazca ridge, an area also characterized by low interseismic coupling, which seems to have repeatedly acted as a barrier to seismic rupture propagation in the past. The seismogenic portion of the megathrust thus appears to be composed of interfingering rate-weakening and rate-strengthening patches. The rate-strengthening patches contribute to a high proportion of aseismic slip, and determine the extent and frequency of large interplate earthquakes. Aseismic slip accounts for as much as 50-70% of the slip budget on the seismogenic portion of the megathrust in central Peru, and the return period of earthquakes with M(w) = 8.0 in the Pisco area is estimated to be 250 years. PMID:20445628

Perfettini, Hugo; Avouac, Jean-Philippe; Tavera, Hernando; Kositsky, Andrew; Nocquet, Jean-Mathieu; Bondoux, Francis; Chlieh, Mohamed; Sladen, Anthony; Audin, Laurence; Farber, Daniel L; Soler, Pierre

2010-05-01

200

Strike-slip earthquakes on moderately-dipping faults  

NASA Astrophysics Data System (ADS)

Moderate-angle faults that form under compressive stress regimes in subduction zones can slip laterally if the stress field subsequently reorients to strike-slip. We present three examples from Japan and Pakistan in which regional-scale thrust faults created in compressional structural settings have been reactivated as strike-slip faults in new, largely subhorizontal, stress fields. (1) In SW Japan, the Median Tectonic Line has a dip of 30-40°, yet it slips laterally in the slip-partitioned Nankai subduction margin. (2) Likewise, the source fault for the M7.9 Great Kanto earthquake was the Sagami megathrust, yet it exhibited predominantly strike-slip movement in the 1923 earthquake. (3) In Pakistan, the 2013 M7.7 Awaran earthquake occurred on a fault plane that dips 45° and showed largely strike-slip movement. These are regional-scale, moderate-angle faults that originated as thrust faults at the subduction interface (or in its associated fold-and-thrust belt) and now exhibit near-horizontal slip. While their current slip behavior suggests they should be oriented vertically or near-vertically, they are not. They have inherited a non-typical inclined geometry. Under what conditions does a thrust fault reactivate in a strike-slip stress field? The inherited fault plane must represent a significant preexisting crustal weakness whose coefficient of cohesion exceeds its coefficient of friction, allowing it to fail preferentially despite its unfavorable orientation. Details of the slip behavior for these faults in time and space suggest complex dynamics which will require further scrutiny.

Van Horne, Anne; Hubbard, Judith; Sato, Hiroshi; Takeda, Tetsuya

2014-05-01

201

Spacesuit mobility joints  

NASA Technical Reports Server (NTRS)

Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

Vykukal, H. C. (inventor)

1978-01-01

202

Slip Distribution and Seismic Moment of the 2010 and 1960 Chilean Earthquakes Inferred from Tsunami Waveforms and Coastal Geodetic Data  

NASA Astrophysics Data System (ADS)

The slip distribution and seismic moment of the 2010 and 1960 Chilean earthquakes were estimated from tsunami and coastal geodetic data. These two earthquakes generated transoceanic tsunamis, and the waveforms were recorded around the Pacific Ocean. In addition, coseismic coastal uplift and subsidence were measured around the source areas. For the 27 February 2010 Maule earthquake, inversion of the tsunami waveforms recorded at nearby coastal tide gauge and Deep Ocean Assessment and Reporting of Tsunamis (DART) stations combined with coastal geodetic data suggest two asperities: a northern one beneath the coast of Constitucion and a southern one around the Arauco Peninsula. The total fault length is approximately 400 km with seismic moment of 1.7 × 1022 Nm (Mw 8.8). The offshore DART tsunami waveforms require fault slips beneath the coasts, but the exact locations are better estimated by coastal geodetic data. The 22 May 1960 earthquake produced very large, ~30 m, slip off Valdivia. Joint inversion of tsunami waveforms, at tide gauge stations in South America, with coastal geodetic and leveling data shows total fault length of ~800 km and seismic moment of 7.2 × 1022 Nm (Mw 9.2). The seismic moment estimated from tsunami or joint inversion is similar to previous estimates from geodetic data, but much smaller than the results from seismic data analysis.

Fujii, Yushiro; Satake, Kenji

2013-09-01

203

Slip velocity dependence on shear-induced permeability evolution  

NASA Astrophysics Data System (ADS)

Evolution of fluid transport properties of a fault zone during seismic slip can influence on the dynamic fault process in a subducing plate boundary, though permeability change caused by dynamic slip motion is less well documented. In this study, we measured water permeability and seismic velocity for high porosity sandstone (Berea sandstone, porosity = 20%), low porosity sandstone (Indian sandstone, 11~14 %) and granite (Aji granite, 0.5 %) after shear deformation at various slip rates from 0.1 to 1300 mm/s in laboratory experiments. Friction tests were performed at low normal stress from 1 to 2MPa and below 10 m of slip displacement. Permeability of Berea sandstone decreases by one order of magnitude with increase in slip rate and slip displacement. Permeability of Indian sandstone and Aji granite increases dramatically by three orders of magnitude at high slip rate above 300 mm/s. Fine grained gouges are developed along simulated slip surface in all rock specimens, and the width of gouge layers are proportional to slip rate and slip displacement. Microcracks and mesoscale fractures are nucleated in specimens at 1300 mm/s of slip velocity. Temperature distribution of specimen in friction experiments estimated by finite element method using laboratory data shows temperature on a slip surface rises several hundred degrees above 130 mm/s of slip velocity, and temperature would have exceeded ?-? phase transition temperature of quartz at 1300 mm/s of slip velocity. The thermal gradient along the axis normal to slip surface is very sweep at high slip rate. Permeability reduction in porous sandstone after friction test is explained by the growth of the finer grained gouge layer, which is less permeable than that of host rocks. A sudden permeability increase for low porosity sandstone and granite is explained by the thermal cracking result from thermal stress induced by rapid and large heat generation at high slip rate. Increase in wear rate of gouge with slip velocity is explained by the reduction of rock strength and enhancement of thermal cracking by temperature rise. The transition from a reduction to increase of permeability by high velocity friction is observed around 10-16 m2 of permeability for intact rocks at 10 MPa of effective pressure. All elastic properties (S and P wave velocities, Poisson’s ratio) for all rocks are not changed by friction at low slip rate below 130 mm/s. S and P wave velocities for Aji granite and Indian sandstone are decreased and Poisson’s ratio is increased by high velocity friction. We observed the decrease in S and P wave velocities and the increase in Poisson’s ratio at 390 mm/s of slip velocity in Berea sandstone, though the changes in these properties were not observed at 1300 mm/s. Our results suggest that the temporal increase in shear strength caused by the dissipation of pore pressure is expected due to the generation of thermal cracking along fault zone, and thus the dynamic permeability change can act as a break of slip. The sudden increase in permeability for impermeable rocks can explain the hydro-geochemical phenomena after earthquake reported by Claesson et al. (2004). Claesson, L. et al., 2004. Hydrogeochemical changes before and after a major earthquake, Geology, 32, 641-644.

Sakaguchi, M.; Tanikawa, W.; Hirose, T.; Tadai, O.; Lin, W.

2009-12-01

204

Premonitory slip and tidal triggering of earthquakes  

USGS Publications Warehouse

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.

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

1999-01-01

205

Self-healing slip pulse on a frictional surface  

Microsoft Academic Search

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,

James R. Rice; Gutuan Zheng

1995-01-01

206

A generating mechanism for apparent fluid slip in hydrophobic microchannels  

Microsoft Academic Search

Fluid slip has been observed experimentally in micro- and nanoscale flow devices by several investigators [e.g., Tretheway and Meinhart, Phys. Fluids 14, L9 (2002); Zhu and Granik, Phys. Rev. Lett. 87, 096105 (2001); Pit &etal;, Phys. Rev. Lett. 85, 980 (2000); and Choi &etal;, Phys. Fluids 15, 2897 (2003)]. This paper examines a possible mechanism for the measured fluid slip,

Derek C. Tretheway; Carl D. Meinhart

2004-01-01

207

Slip flow through colloidal crystals of varying particle diameter.  

PubMed

Slip flow of water through silica colloidal crystals was investigated experimentally for eight different particle diameters, which have hydraulic channel radii ranging from 15 to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 10(10) Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63 ± 3 nm. A flow enhancement of 20 ± 2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high-volume flow rates. PMID:23237590

Rogers, Benjamin J; Wirth, Mary J

2013-01-22

208

Slip-Free Driving Method for Nonresonant Piezoelectric Actuator  

Microsoft Academic Search

It is generally considered that in the ultrasonic motor the motion always slips and scratches. The nonresonant ultrasonic motor (NRUSM) expected for future precision stage systems should, however, overcome the difficulties of the wear of friction materials, which has been encountered in the use of conventional ultrasonic motors. The wear occurs by slipping and may be reduced by material selection.

Taishi Endo; Yoshiya Egashira; Hiroyuki Furukawa; Hiroyuki Hashiguchi; Kouji Kosaka; Masayuki Watanabe; Noboru Miyata; Shirou Moriyama; Syunichi Sasaki; Akira Nakada; Tadahiro Ohmi; Hiroshi Kubota

2005-01-01

209

Slip Flow through Colloidal Crystals of Varying Particle Diameter  

PubMed Central

Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates.

Rogers, Benjamin J.; Wirth, Mary J.

2012-01-01

210

Friction and Slip in the Cold Rolling of Metals  

Microsoft Academic Search

Friction and slip in the cold rolling of metals were studied theoretically using a mixed lubrication model. The calculated results generally agree with published observations as follows: (1) tension, reduction, oil viscosity, speed, and alloy are important to slip, (2) reduction, oil viscosity, roll radius, speed, and alloy are important to friction, (3) a decrease in friction does not always

Y. H. Tsao; L. B. Sargent Jr

1978-01-01

211

Estimation of vehicle side slip angle using hybrid observer  

Microsoft Academic Search

The vehicle side slip angle is an important matter of vehicle stability control, and it is usually obtained by estimation method today. A hybrid observer is proposed to estimate the vehicle side slip angle in this paper. The hybrid observer includes three parts: a state-space observer, a kinematics integration module and a weight distribution module. The weighting distribution module includes

Shang Mingli; Chu Liang; Guo Jianhua; Fang Yong

2010-01-01

212

Deriving fault-slip histories to test for secular variation in slip, with examples from the Kunlun and Awatere faults  

NASA Astrophysics Data System (ADS)

Although offset and age data from displaced landforms are essential for identifying earthquake clusters and thus testing whether faults slip at uniform or secularly varying rates, it is not clear how the uncertainties in such measurements should be propagated so as to yield a robust fault-slip history (i.e., record of fault displacement over time). Here we develop a Monte Carlo approach for estimating the distribution of geologically reasonable fault-slip histories that fit the offset and age data from a population of dated and displaced landforms. The model assumes that the landforms share common faulting histories, the offset and age constraints are correct, and the fault has not reversed shear sense. Analysis of the model results yields both a precise average slip rate, in the case where a linear fit is applied to the data, and a best-fit fault-slip history, in the case where the linear constraint is removed. The method can be used to test for secular variation in slip because the uncertainty on this best-fit history is quantified. By applying the method to previously published morphochronologic data from faulted late Quaternary terrace risers along the Kunlun fault in China and the Awatere fault in New Zealand, we have assessed the extent to which our modeled average slip rates match previously reported values and the data support previous interpretations of uniform slip rate. The Kunlun data set yields average slip rates of 8.7 + 3.6/-2.1 mm/yr and 5.1 + 1.6/-1.2 mm/yr (68.27% confidence), for the central and eastern reaches of the fault, respectively, both of which match previously published slip rates. Our analysis further indicates that these fault reaches have both slipped uniformly over the latest Quaternary. In contrast, analysis of data from the Saxton River site along the Awatere fault reveals a mid-Holocene deceleration in slip rate from 6.2 + 1.6/-1.4 mm/yr to 2.8 + 1.0/-0.6 mm/yr. This result contradicts previous interpretations of uniform slip along the Awatere fault. The Monte Carlo method we present here for quantifying fault-slip histories using the offset and age data from a population of faulted landforms provides an important tool for distinguishing temporally uniform from secularly varying fault slip.

Gold, Ryan D.; Cowgill, Eric

2011-01-01

213

Imaging fault slip variation along the central San Andreas fault from satellite, airborne InSAR and GPS  

NASA Astrophysics Data System (ADS)

The improved spatiotemporal resolution of surface deformation from recent satellite and airborne InSAR measurements provides great potential to improve our understanding of faulting processes and earthquake hazard for a given fault system. A major plate boundary fault in central California, the central San Andreas fault (CSAF) displays a spectrum of complex fault slip behaviors with creeping in its central segment that decreases towards its northwest and southeast ends where the fault transitions to being locked. In the north the CSAF branches into two sub-parallel faults that are both actively accommodating plate motion. To the south, near the Parkfield transition, large earthquakes have occurred with at least six Mw ~6.0 events since 1857, most recently in 2004. To understand the complexity and variety of fault slip behaviors and fault mechanics, we integrate satellite and airborne synthetic aperture radar (SAR) repeat pass interferometry (RPI) observations, with GPS measurements from the Plate Boundary Observatory (PBO) and regional campaign networks to estimate fault slip and shallow slip deficits along the CSAF. Existing C-band ERS-1/2, Envisat and Radarsat SAR data provide long archives of SAR data over the region but are subject to severe decorrelation. The Japan Aerospace Exploration Agency's ALOS satellite has made less frequent acquisitions (5-6/yr per track) since 2006 but its PALSAR L-band sensor provides much improved coherence compared to shorter wavelength radar data. More recently, the NASA UAVSAR airborne SAR has repeated fault perpendicular adjacent swaths imaged from opposing look directions and fault parallel swath flights over the CSAF over the past three years and provides an improved imaging of fault slip related deformation at finer spatial resolution than previous platforms (~6m at 12 azimuth x 3 range looks). Compared to C-band instruments, the UAVSAR provides nearly complete spatial coverage. Compared to the ALOS mission, the UAVSAR's flight paths are optimized for fault parallel motion sensitivity, whereas the ALOS satellite data were almost exclusively acquired on ascending paths that looked nearly perpendicular to the fault strike. Joint analysis of UAVSAR and ALOS RPI measurements show clear variability in deformation along fault strike. Initial modeling at selected fault transects from the creeping section using UAVSAR data suggests fault creep increases from the surface to a shallower depth and decreases at lower upper crustal depths (~6-9 km). The fault slip rate at depths greater than 12 km is weakly constrained and subject to long wavelength noise components. We are examining the integrated resolution capability of UAVSAR, ALOS, and GPS for estimating fault slip with the goal of mapping fault slip along the entire length of the CSAF in a systematic imaging effort.

Liu, Z.; Lundgren, P.; Fielding, E. J.; Hensley, S.

2011-12-01

214

Effective slip on textured superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

We study fluid flow in the vicinity of textured and superhydrophobically coated surfaces with characteristic texture sizes on the order of 10 ?m. Both for droplets moving down an inclined surface and for an external flow near the surface (hydrofoil), there is evidence of appreciable drag reduction in the presence of surface texture combined with superhydrophobic coating. On textured inclined surfaces, the drops roll faster than on a coated untextured surface at the same angle. The highest drop velocities are achieved on surfaces with irregular textures with characteristic feature size ~8 ?m. Application of the same texture and coating to the surface of a hydrofoil in a water tunnel results in drag reduction on the order of 10% or higher. This behavior is explained by the reduction of the contact area between the surface and the fluid, which can be interpreted in terms of changing the macroscopic boundary condition to allow nonzero slip velocity.

Gogte, Salil; Vorobieff, Peter; Truesdell, Richard; Mammoli, Andrea; van Swol, Frank; Shah, Pratik; Brinker, C. Jeffrey

2005-05-01

215

Slipped capital femoral epiphysis in children.  

PubMed

Two new classification schemes have been described for slipped capital femoral epiphysis (SCFE); both involve the question of stability and are probably more prognostic than the traditional acute or chronic classification. The prevalence of bilaterality is approximately 33%, and two recent series regarding bilateral SCFE recommend frequent follow-up after a child presents with a unilateral SCFE, but they do not recommend prophylactic pinning of the normal hip. In the case of a child with an underlying endocrine disorder who presents with a unilateral SCFE, however, strong consideration should be given to prophylactic pinning of the opposite hip. The most commonly accepted method of fixation at this time is in situ pin fixation with a single central screw. The screw head should be no more than 1.5 cm from the cortex of the femur to prevent windshield-wiper loosening. Chondrolysis, a complication of both untreated and treated SCFE, has a more favorable prognosis than idiopathic chondrolysis. PMID:7728212

Loder, R T

1995-02-01

216

Regulating the working properties of porcelain slip  

SciTech Connect

It was decided to introduce changes in the recipe of the clay part of the raw material to provide a reduction in the density and a restoration of the Prosyyanovsk kaolin (PK) slip's fluidity, the volume of the PK batch would be maintained, and the working properties of the body could be insured within the same limits as prevailed before recipe of the stone materials and the chemical composition of the porcelain would be left unchanged. The results indicate the effectiveness of using the analytical method for clay suspensions for operational assessment of the technical properties of raw materials and regulating the working properties of the body. The method of filtration analysis and determination of the elastic properties of the suspension can also be recommended for use in benefication combines. The advantage of the methods consists in the rapidity of carrying out the analysis which means where necessary can operationally intervene in the technological process.

Karpilovskii, L.P.; Kralinina, L.N.; Makarov, V.A.; Sidorenko, Z.I.

1986-05-01

217

Thermal slip for liquids at rough solid surfaces  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation is used to examine the thermal slip of liquids at rough solid surfaces as characterized by fractal Cantor structures. The temperature profiles, potential energy distributions, thermal slip, and interfacial thermal resistance are investigated and evaluated for a variety of surface topographies. In addition, the effects of liquid-solid interaction, surface stiffness, and boundary condition on thermal slip length are presented. Our results indicate that the presence of roughness expands the low potential energy regions in adjacent liquids, enhances the energy transfer at liquid-solid interface, and decreases the thermal slip. Interestingly, the thermal slip length and thermal resistance for liquids in contact with solid surfaces depends not only on the statistical roughness height, but also on the fractal dimension (i.e., topographical spectrum).

Zhang, Chengbin; Chen, Yongping; Peterson, G. P.

2014-06-01

218

Effective slip over superhydrophobic surfaces in thin channels.  

PubMed

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a microscopic texture. Recent work has focused on specific cases, such as arrays of pillars or grooves, 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. Tighter bounds for isotropic textures further constrain the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces. PMID:19257293

Feuillebois, François; Bazant, Martin Z; Vinogradova, Olga I

2009-01-16

219

Effective Slip over Superhydrophobic Surfaces in Thin Channels  

NASA Astrophysics Data System (ADS)

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a microscopic texture. Recent work has focused on specific cases, such as arrays of pillars or grooves, 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. Tighter bounds for isotropic textures further constrain the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces.

Feuillebois, François; Bazant, Martin Z.; Vinogradova, Olga I.

2009-01-01

220

Studies on the spermatogenic sulfogalactolipid binding protein SLIP 1.  

PubMed

We have purified the testicular sulfogalactolipid binding protein SLIP 1 and shown by photoaffinity labeling that it contains an ATP binding site. Purified SLIP 1 was fluorescently labeled and shown to retain specific sulfogalactolipid binding function. This probe was used to investigate the topology of SLIP 1 binding sites on testicular germ cells. The binding pattern precisely coincided with the previously demonstrated asymmetric surface domains of sulfogalactoglycerolipid (SGG). Occasionally these SGG-containing, SLIP 1-binding cell surface domains exactly coincided with structural features on the cell surface as detected by differential interference contrast microscopy. These results demonstrate that SLIP 1/SGG interactions could provide an effective intercellular communication network between testicular germ cells within the seminiferous tubule. PMID:1999474

Lingwood, C; Nutikka, A

1991-02-01

221

Nailing down the slip rate of the Altyn Tagh fault  

NASA Astrophysics Data System (ADS)

estimates of the geodetic and geologic slip rates of the 1500 km long Altyn Tagh fault bordering the northern edge of the Tibetan plateau vary by a factor of five. Proposed reasons for these discrepancies include poor GPS geometry, interpretative errors in terrace morphology, and changes in fault slip rate over time. Here we present results from a new dense GPS array orthogonal to the fault at ~86.2°E that indicates a velocity of 9.0-3.2/+4.4 mm/yr, in close agreement with geomorphologic estimates at the same location. Our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets. The resulting mean combined geological and geodetic slip rate (9.0 ± 4.0 mm/yr) is remarkably uniform for the central ~800 km of the Altyn Tagh fault, significantly lower than early kinematic estimates and consistent with deformation elsewhere in Tibet and central Asia.

He, Jiankun; Vernant, Philippe; Chéry, Jean; Wang, Weimin; Lu, Shuangjiang; Ku, Wenfei; Xia, Wenhai; Bilham, Roger

2013-10-01

222

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

223

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

We present a new method for inverting coseismic slip distribution based on arc measurements of InSAR interferograms. The method only solves the integer ambiguities on the selected arcs so that the challenging task from global unwrapping of low coherence interferograms can be avoided. The simulated experiment results show that the new method recovered the given slip distribution well at different coherence quality levels. However, the conventional method with global interferogram unwrapping fails when the interferogram has some isolated areas. In addition, the new method is capable of using surface rupture offset data gathered in the field. We apply the proposed method to study the 2010 Yushu, China Ms 7.1 earthquake. Inclusion of field data can help to enhance the results of fault slip inversion. It derives a maximum slip of ∼3 m, larger than the published coseismic slip results on this event, but agreeing with the largest offset of 3.2 m from field investigation.

Wang, C.; Ding, X.; Li, Q.

2014-03-01

224

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

We present a new method for inverting coseismic slip distribution based on arc measurements of InSAR interferograms. The method only solves the integer ambiguities on the selected arcs so that the challenging task from global unwrapping of low coherence interferograms can be avoided. The simulated experiment results show that the new method recovered the given slip distribution well in different coherence quality level. However, the conventional method with global interferogram unwrapping fails when the interferogram has some isolated areas. In addition, the new method is capable of using surface rupture offset data gathered in the field. We apply the proposed method to study the 2010 Yushu, China Ms = 7.1 earthquake. Inclusion of field data can help to enhance the results of fault slip inversion. It derives a maximum slip of ∼3 m, larger than the published coseismic slip results on this event, but agreeing with the largest offset of 3.2 m from field investigation.

Wang, C.; Ding, X.; Li, Q.

2013-12-01

225

Learning and Prediction of Slip from Visual Information  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

226

[Vascularized joint transfer for finger joint reconstruction].  

PubMed

In a retrospective clinical study 16 vascularized joint transfers to the hand with an average follow-up of 8.2 (3 - 15) years were evaluated. The finger joint defect was caused by trauma in 12 patients, tumour in 2 patients and infection and congenital deformity in 1 patient each. There were 14 men and 2 women. The mean age range was 26 (2 - 42) years. In 6 cases a partial vascularized joint transfer was carried out, with the transplant being harvested in two cases from non-replantable finger according to the "tissue bank concept" according to Chase and in the other two cases from the PIP-joint of the second toe. In 10 patients a complete vascularized joint transfer was carried out, with the joint being harvested from the hand in 6 cases and from the 2nd toe in 4 cases. The following criteria were evaluated: active range of motion (neutral-0-method), postoperative arthritis, growth and complications. Active range of motion of the transplanted joint was for partial PIP-joint transfer Ex/Flex 0/20/65 degrees und for partial MP-joint transfer 0/20/30 degrees . After DIP-to-PIP-joint transposition active range of motion was measured Ex/Flex 0/20/60 degrees , after PIP-to-PIP transposition 0/30/60 degrees , PIP-to-MP-transposition 0/20/80 degrees and after MP-to-MP-transposition 0/20/57 degrees . The results after microvascular PIP-joint transfer from the 2nd toe for PIP-joint reconstruction were 0/25/58 degrees for PIP-joint reconstruction and 0/15/70 degrees for MP-joint reconstruction. Arthritic changes could be seen in 3 out of 4 patients with partial vascularized joint transfer. In all complete joint transfers there was no clinical and radiological evidence of arthritis even after 15 years. In the two skeletal immature patients at the time of transfer, normal growth compared to the contralateral donor site could be seen. In 8 out of 14 patients complications occurred. In 4 cases tendolysis of the extensor tendon was necessary. In 4 patients skeletal malalignment (3 x sagittal plane, 1 x rotation) was diagnosed. In one patient flexor pulley reconstruction was necessary in order to correct a bowstring deformity. Indications for vascularized joint transfer at the finger in children is set because of lack of therapy option offering normal growth potential. In adults vascularized joint transfer is indicated in case of contraindication for prosthetic joint replacement or arthrodesis. PMID:17724645

Hierner, R; Berger, A K; Shen, Z-L

2007-08-01

227

Interfacial debonding of pipe joints under torsion loads: a model for arbitrary nonlinear cohesive laws  

Microsoft Academic Search

Adhesively bonded pipe joints are extensively used in pipelines. In the present work, Cohesive Zone Model (CZM) based analytical\\u000a solutions are obtained for the bonded pipe joints under torsion. An integral form based general expression is derived which\\u000a is suitable for arbitrary type of nonlinear cohesive laws. The concept of the minimum interfacial cohesive shear slip ?\\u000a \\u000a m\\u000a is introduced

Zhenyu Ouyang; Guoqiang Li

2009-01-01

228

How informative are slip models for aftershock forecasting?  

NASA Astrophysics Data System (ADS)

Coulomb stress changes (?CFS) have been recognized as a major trigger mechanism for earthquakes, in particular aftershock distributions and the spatial patterns of ?CFS are often found to be correlated. However, the Coulomb stress calculations are based on slip inversions and the receiver fault mechanisms which both contain large uncertainties. In particular, slip inversions are usually non-unique and often differ strongly for the same earthquakes. Here we want to address the information content of those inversions with respect to aftershock forecasting. Therefore we compare the slip models to randomized fractal slip models which are only constrained by fault information and moment magnitude. The uncertainty of the aftershock mechanisms is considered by using many receiver fault orientations, and by calculating ?CFS at several depth layers. The stress change is then converted into an aftershock probability map utilizing a clock advance model. To estimate the information content of the slip models, we use an Epidemic Type Aftershock Sequence (ETAS) model approach introduced by Bach and Hainzl (2012), where the spatial probability density of direct aftershocks is related to the ?CFS calculations. Besides the directly triggered aftershocks, this approach also takes secondary aftershock triggering into account. We quantify our results by calculating the information gain of the randomized slip models relative to the corresponding published slip model. As case studies, we investigate the aftershock sequences of several well-known main shocks such as 1992 Landers, 1999 Hector Mine, 2004 Parkfield, 2002 Denali. First results show a huge difference in the information content of slip models. For some of the cases up to 90% of the random slip models are found to perform better than the originally published model, for some other cases only few random models are found performing better than the published slip model.

Bach, Christoph; Hainzl, Sebastian

2013-04-01

229

Constraining fault constitutive behavior with slip and stress heterogeneity  

USGS Publications Warehouse

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.

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

2008-01-01

230

71 FR 2879 - Steel Erection; Slip Resistance of Skeletal Structural Steel  

Federal Register 2010, 2011, 2012, 2013

...appropriate to evaluate the slip resistance of wetted, coated skeletal...that comply with the slip resistance criterion of the Standard...Institute of Steel Construction, Metal Building Manufacturers Association...754-.758). The slip resistance provision was not...

2006-01-18

231

Lattice Boltzmann Simulations of Skin-Friction Drag Reduction in Turbulent Channel Flow with Slip/No Slip Wall Ridges  

NASA Astrophysics Data System (ADS)

To gain a better understanding of the mechanisms at work in skin friction drag reduction with superhydrophobic surfaces, Lattice Boltzmann simulations were performed in turbulent channels with alternating slip/no slip ridges on the walls. Simulations were performed in turbulent channels of size 5h x2.5 x2h and 10h x5h x2h at a base Reynolds number of Re?˜230. Alternating slip/no slip ridges of width 4 <=w+ <=140, aligned in the streamwise direction, all with the same fractional area of slip boundary, were studied. Drag reductions of 4%, 8%, 21%, 33% and 47%, corresponding to slip velocities of Uslip/Ubulk= 0.05, 0.1, 0.26, 0.31 and 0.36 were observed for w+=g+= 4, 8, 40, 70 and 140, respectively. The mean velocity profiles display the characteristics of combined slip described by Min and Kim [Min et al. 2004]. The streamwise and spanwise turbulence intensities show large slips at the wall, the magnitude of which increases with increasing drag reduction. Examination of the anisotropy invariant maps shows a shift of turbulence structure towards the one-dimensional turbulence limit near the wall with increasing drag reduction. For z^+ > 25, the turbulence structure returns to the isotropic limit.

Rastegari, Amirreza; Akhavan, Rayhaneh

2011-11-01

232

Design and Analysis of Closed Loop Microprocessor Based Static Slip Energy Recovery Controlled Slip Ring Induction Motor Drive  

Microsoft Academic Search

In this paper the complete design and analysis of microprocessor based closed loop static slip energy recovery controlled slip ring induction motor drive is presented. The speed and current controllers are implemented using INTEL-8085 microprocessor. The set of non -linear differential equations of the drive based on d c equivalent circuit are linearized around an operating point. Using forward approximation

B. K. SINGH

233

Proprioception and joint stability  

Microsoft Academic Search

In the present paper the current clinical knowledge about proprioception is given for the shoulder, knee, ankle, elbow and the radiocarpal joint. Proprioceptive capabilities are decreased after joint injuries such as ACL or meniscus tears, shoulder dislocation, ankle sprain and in joints with degenerative joint disease. Some surgical procedures seem to restore the proprioceptive abilities; others do not. Elastic knee

J. Jerosch; M. Prymka

1996-01-01

234

Historic creep rate and potential for seismic slip along the Hayward Fault, California  

NASA Astrophysics Data System (ADS)

The Hayward fault is considered the most likely source of one or more major earthquakes in the San Francisco Bay area in the next few decades. Historically, at least one, and probably two, major earthquakes (about M 6.8) occurred along the Hayward fault, one in 1836 and another in 1868. Little is known about the 1836 event, but the 1868 earthquake was accompanied by a surface rupture that extended as much as 41 km along the southern part of the fault. Although the amount of surface slip in 1868 is uncertain, right slip (including afterslip) reached at least several centimeters, and possibly several decimeters in places. This paper documents the spatial variation of creep rate along the Hayward fault since the 1868 earthquake. Creep (aseismic fault slip) occurs over at least 66 km and may extend over the fault's entire 82-km length, of which about 13 km lies underwater. Creep rate seems nearly constant over decades, but short-term variations occur. We derive creep rate mainly from our own systematic surveying of offset cultural features (curbs, fences, and buildings). On each feature we solve directly for accumulated creep by using multiple linear regression. Creep rate mostly falls in the range of 3.5-6.5 mm/yr; but systematic variation occurs along strike. Fault segments with distinctly higher and lower rates generally correspond to parts of the fault most salient from the overall average alinement of the fault. Most distinctive is a 4-km-long section near the south end of the fault that creeps at about 9 mm/yr. Such a high rate has occurred there at least since the 1920s and probably since the 1868 earthquake, as indicated by an offset railroad track built in 1869. We suggest that this 9 mm/yr slip rate may approach the long-term or deep slip rate that controls average recurrence interval between major earthquakes. If so, assuming an elastic rebound model, the potential for slip in large earthquakes below the surficial creeping zone is now ˜1.1 m in the southern (1868) segment of the fault and ? 1.4 m in the northern (1836?) segment. Subtracting surface creep rates from a long-term slip rate of 9 mm/yr gives present potential for surface slip in large earthquakes of up to 0.8 m, with an average of 0.6 m in the northern segment and 0.4 m in the southern segment. We present a simple hypothesis for rupture potential that is compatible with historic creep rate, microseismicity distribution, and geodetic data. If seismic rupture occurs on segments 41 km long by 10 km deep (7 km fully locked, 3 km creeping), today's potential for seismic moment release is 1.4 × 1019 and 1.1 × 1019 N m for both 1836? and 1868 segments, respectively, and 2.5 × 1019 N m for both segments jointly. Converting moment to magnitude gives ML 6.8 in the northern segment, ML 6.7 in the southern segment, and ML 7.0 for simultaneous rupture of both.

Lienkaemper, J. J.; Borchardt, G.; Lisowski, M.

1991-10-01

235

Repeated-Slip Training: An Emerging Paradigm for Prevention of Slip-Related Falls Among Older Adults  

PubMed Central

Falls frequently cause injury-related hospitalization or death among older adults. This article reviews a new conceptual framework on dynamic stability and weight support in reducing the risk for falls resulting from a forward slip, based on the principles of motor control and learning, in the context of adaptation and longer-term retention induced by repeated-slip training. Although an unexpected slip is severely destabilizing, a recovery step often is adequate for regaining stability, regardless of age. Consequently, poor weight support (quantified by reduction in hip height), rather than instability, is the major determinant of slip-related fall risk. Promisingly, a single session of repeated-slip training can enhance neuromechanical control of dynamic stability and weight support to prevent falls, which can be retained for several months or longer. These principles provide the theoretical basis for establishing task-specific adaptive training that facilitates the development of protective strategies to reduce falls among older adults.

Pai, YC; Bhatt, TS

2009-01-01

236

Repeated-slip training: an emerging paradigm for prevention of slip-related falls among older adults.  

PubMed

Falls frequently cause injury-related hospitalization or death among older adults. This article reviews a new conceptual framework on dynamic stability and weight support in reducing the risk for falls resulting from a forward slip, based on the principles of motor control and learning, in the context of adaptation and longer-term retention induced by repeated-slip training. Although an unexpected slip is severely destabilizing, a recovery step often is adequate for regaining stability, regardless of age. Consequently, poor weight support (quantified by reduction in hip height), rather than instability, is the major determinant of slip-related fall risk. Promisingly, a single session of repeated-slip training can enhance neuromechanical control of dynamic stability and weight support to prevent falls, which can be retained for several months or longer. These principles provide the theoretical basis for establishing task-specific adaptive training that facilitates the development of protective strategies to reduce falls among older adults. PMID:17712033

Pai, Yi-Chung; Bhatt, Tanvi S

2007-11-01

237

Observations of premonitory acoustic emission and slip nucleation during a stick slip experiment in smooth faulted Westerly granite  

USGS Publications Warehouse

To investigate laboratory earthquakes, stick-slip events were induced on a saw-cut Westerly granite sample by triaxial loading at 150 MPa confining pressure. Acoustic emissions (AE) were monitored using an innovative continuous waveform recorder. The first motion of each stick slip was recorded as a large-amplitude AE signal. These events source locate onto the saw-cut fault plane, implying that they represent the nucleation sites of the dynamic failure stick-slip events. The precise location of nucleation varied between events and was probably controlled by heterogeneity of stress or surface conditions on the fault. The initial nucleation diameter of each dynamic instability was inferred to be less than 3 mm. A small number of AE were recorded prior to each macro slip event. For the second and third slip events, premonitory AE source mechanisms mimic the large scale fault plane geometry. Copyright 2005 by the American Geophysical Union.

Thompson, B. D.; Young, R. P.; Lockner, D. A.

2005-01-01

238

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

239

[Total joint arthroplasty].  

PubMed

Control of the disease activity is enabled due to the progress of drug therapy for rheumatoid arthritis. However, surgical treatments are necessary for unresponsive cases to the drug or for achieving higher QOL, and we can attain more tight control or cure by combination of drug therapy and surgical treatments. Total joint arthroplasty provides indolence, mobility, stability and is an useful joint reconstruction method. Shoulder and elbow joint work as a reach function together, and total joint arthroplasty become adaptation when extensive joint destruction or severe pain occurrs. With the usage of biologic agents joint repair is possible in small joints, but if the joint destruction progress in weight-bearing joints, repair is impossible and total joint arthroplasty can be required. PMID:23961679

Mibe, Junya; Yamamoto, Kengo

2013-07-01

240

Effect of Water on High Pressure Olivine Slip Systems Activity  

NASA Astrophysics Data System (ADS)

Seismologic studies of the Earth's shallow (Z<220 km) upper mantle have observed seismic anisotropy parallel to the direction of plate movement and have related this observation to alignment of olivine [100] due to shearing related to convection. These observations have been reinforced by field-based and experimental investigations which observe evidence that [100] slip is dominant at low pressures and water contents. However, direct evidence of the dominant slip system in the deep upper mantle (Z>220 km) is limited to a few studies of xenoliths which have LPOs consistent with [001] slip. Experimental studies of dry single crystals and polycrystals indicate that [001] slip becomes dominant at pressures > 8 GPa. However, water contents in the mantle are significant (~1000 H/106 Si) and we do not know how the slip systems of olivine are affected by higher water contents at high pressures. In order to investigate the effect of pressure on slip systems activities in olivine deformed in wet conditions, deformation experiments were carried out on single crystals, at pressure ranging from 4 to 8 GPa and temperature between 1373 and 1473 K in the Deformation-DIA apparatus (D-DIA) of the X17B2 beamline of the NSLS (NY, USA). Specimen were deformed in uniaxial compression along [110]c, [011]c and [101]c crystallographic directions, promoting the activation of, respectively, [100](010), [001](010) slip systems, and simultaneously [100](001) and [001](100) slip systems. Talc sleeves about the annulus of the single crystals were used as source of water during deformation. In addition, run products investigation using a micro-focused IR beam at the U2 beamline enables accurate mapping of the water content across the deformed single crystals using FTIR spectroscopy, while specimen deformation microstructures were investigated by TEM. We observe a slip-system transition in wet specimen occurring at lower pressure than that observed by Raterron et al. (2007) in dry specimens. For each investigated crystal orientation, the pressure effect on the slip-system activity has been quantified and the hydrolytic weakening has also been estimated. Our results confirm that pressure induces the dominant slip system transition in olivine, and show that water lowers the transition pressure by weakening [001] slip more significant than [100] slip.

Girard, J.; Chen, J.; Raterron, P. C.; Holyoke, C. W.

2012-12-01

241

Real-time inversions for finite fault slip models and rupture geometry based on high-rate GPS data  

NASA Astrophysics Data System (ADS)

We present an inversion strategy capable of using real-time high-rate GPS data to simultaneously solve for a distributed slip model and fault geometry in real time as a rupture unfolds. We employ Bayesian inference to find the optimal fault geometry and the distribution of possible slip models for that geometry using a simple analytical solution. By adopting an analytical Bayesian approach, we can solve this complex inversion problem (including calculating the uncertainties on our results) in real time. Furthermore, since the joint inversion for distributed slip and fault geometry can be computed in real time, the time required to obtain a source model of the earthquake does not depend on the computational cost. Instead, the time required is controlled by the duration of the rupture and the time required for information to propagate from the source to the receivers. We apply our modeling approach, called Bayesian Evidence-based Fault Orientation and Real-time Earthquake Slip, to the 2011 Tohoku-oki earthquake, 2003 Tokachi-oki earthquake, and a simulated Hayward fault earthquake. In all three cases, the inversion recovers the magnitude, spatial distribution of slip, and fault geometry in real time. Since our inversion relies on static offsets estimated from real-time high-rate GPS data, we also present performance tests of various approaches to estimating quasi-static offsets in real time. We find that the raw high-rate time series are the best data to use for determining the moment magnitude of the event, but slightly smoothing the raw time series helps stabilize the inversion for fault geometry.

Minson, S. E.; Murray, Jessica R.; Langbein, John O.; Gomberg, Joan S.

2014-04-01

242

Effective slip in pressure-driven Stokes flow  

NASA Astrophysics Data System (ADS)

Nano-bubbles have recently been observed experimentally on smooth hydrophobic surfaces; cracks on a surface can likewise be the site of bubbles when partially wetting fluids are used. Because these bubbles may provide a zero shear stress boundary condition and modify considerably the friction generated by the solid boundary, it is of interest to quantify their influence on pressure-driven flow, with particular attention given to small geometries. We investigate two simple configurations of steady pressure-driven Stokes flow in a circular pipe whose surface contains periodically distributed regions of zero surface shear stress. In the spirit of experimental studies probing slip at solid surfaces, the effective slip length of the resulting flow is evaluated as a function of the degrees of freedom describing the surface heterogeneities, namely the relative width of the no-slip and no-shear stress regions and their distribution along the pipe. Comparison of the model with experimental studies of pressure-driven flow in capillaries and microchannels reporting slip is made and a possible interpretation of the experimental results is offered which is consistent with a large number of distributed slip domains such as nano-size and micron-size nearly flat bubbles coating the solid surface. Further, the possibility is suggested of a shear-dependent effective slip length, and an explanation is proposed for the seemingly paradoxical behaviour of the measured slip length increasing with system size, which is consistent with experimental results to date.

Lauga, Eric; Stone, Howard A.

2003-08-01

243

Rupture dynamics with energy loss outside the slip zone  

USGS Publications Warehouse

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 which an abrupt uniform drop of shear traction on the fault spreads from a point, Coulomb yielding occurs on the extensional side of the fault. Plastic strain is distributed with uniform magnitude along the fault, and it has a thickness normal to the fault proportional to propagation distance. Energy loss off the fault is also proportional to propagation distance, and it can become much larger than energy loss on the fault specified by the fault constitutive relation. The slip velocity function could be produced in an equivalent elastic problem by a slip-weakening friction law with breakdown slip Dc increasing with distance. Fracture energy G and equivalent Dc will be different in ruptures with different initiation points and stress drops, so they are not constitutive properties; they are determined by the dynamic solution that arrives at a particular point. Peak slip velocity is, however, a property of a fault location. Nonelastic response can be mimicked by imposing a limit on slip velocity on a fault in an elastic medium.

Andrews, D. J.

2005-01-01

244

Perception of slipperiness and prospective risk of slipping at work  

PubMed Central

Objectives Falls are a leading cause of injury at work, and slipping is the predominant cause of falling. Prior research has suggested a modest correlation between objective measures (such as coefficient of friction, COF) and subjective measures of slipperiness (such as worker perceptions) in the workplace. However, the degree of association between subjective measures and the actual risk of slipping at the workplace is unknown. This study examined the association between perception of slipperiness and the risk of slipping. Methods 475 workers from 36 limited-service restaurants participated in a 12-week prospective cohort study. At baseline, demographic information was collected, participants rated floor slipperiness in eight areas of the restaurant, and work environment factors, such as COF, were measured. Restaurant-level and area-level mean perceptions of slipperiness were calculated. Participants then reported their slip experience at work on a weekly basis for the next 12?weeks. The associations between perception of slipperiness and the rate of slipping were assessed. Results Adjusting for age, gender, body mass index, education, primary language, mean COF, use of slip-resistant shoes, and restaurant chain, each 1-point increase in mean restaurant-level perception of slipperiness (4-point scale) was associated with a 2.71 times increase in the rate of slipping (95% CI 1.25 to 5.87). Results were similar for area-level perception within the restaurant (rate ratios (RR) 2.92, 95% CI 2.41 to 3.54). Conclusions Perceptions of slipperiness and the subsequent rate of slipping were strongly associated. These findings suggest that safety professionals, risk managers and employers could use aggregated worker perceptions of slipperiness to identify slipping hazards and, potentially, to assess intervention effectiveness.

Courtney, Theodore K; Verma, Santosh K; Chang, Wen-Ruey; Huang, Yueng-Hsiang; Lombardi, David A; Brennan, Melanye J; Perry, Melissa J

2013-01-01

245

Simulation of the frictional stick-slip instability  

NASA Astrophysics Data System (ADS)

A lattice solid model capable of simulating rock friction, fracture and the associated seismic wave radiation is developed in order to study the origin of the stick-slip instability that is responsible for earthquakes. The model consists of a lattice of interacting particles. In order to study the effect of surface roughness on the frictional behavior of elastic blocks being rubbed past one another, the simplest possible particle interactions were specified corresponding to radially dependent elastic-brittle bonds. The model material can therefore be considered as round elastic grains with negligible friction between their surfaces. Although breaking of the bonds can occur, fracturing energy is not considered. Stick-slip behavior is observed in a numerical experiment involving 2D blocks with rough surfaces being rubbed past one another at a constant rate. Slip is initiated when two interlocking asperities push past one another exciting a slip pulse. The pulse fronts propagate with speeds ranging from the Rayleigh wave speed up to a value between the shear and compressional wave speeds in agreement with field observations and theoretical analyses of mode-II rupture. Slip rates are comparable to seismic rates in the initial part of one slip pulse whose front propagates at the Rayleigh wave speed. However, the slip rate is an order of magnitude higher in the main part of pulses, possibly because of the simplified model description that neglected intrinsic friction and the high rates at which the blocks were driven, or alternatively, uncertainty in slip rates obtained through the inversion of seismograms. Particle trajectories during slip have motions normal to the fault, indicating that the fault surfaces jump apart during the passage of the slip pulse. Normal motion is expected as the asperities on the two surfaces ride over one another. The form of the particle trajectories is similar to those observed in stick-slip experiments involving foam rubber blocks ( Brune et al., 1993). Additional work is required to determine whether the slip pulses relate to the interface waves proposed by Brune and co-workers to explain the heat-flow paradox and whether they are capable of inducing a significant local reduction in the normal stress. It is hoped that the progressive development of the lattice solid model will lead to realistic simulations of earthquake dynamics and ultimately, provide clues as to whether or not earthquakes are predictable.

Mora, Peter; Place, David

1994-03-01

246

Cooperative atomic motions and core rearrangement in dislocation cross slip  

NASA Astrophysics Data System (ADS)

Atomistic study of cross slip of a screw dislocation in copper is presented using the action-optimization numerical technique which seeks the most probable dynamic pathway on the potential-energy surface of the atomic system during the cross-slip process. The observed mechanism reveals features of both competing mechanisms postulated in literature, i.e., the Fleischer mechanism and the Friedel-Escaig mechanism. Due to cooperative atomic motions and complex core rearrangement during the process, the activation energies of the current cross-slip mechanism are around 0.5 eV less than the lowest ever reported in corresponding studies using atomistic numerical techniques.

Pendurti, Srinivas; Jun, Sukky; Lee, In-Ho; Prasad, Vish

2006-05-01

247

Micro PIV measurement of slip flow on a hydrogel surface  

NASA Astrophysics Data System (ADS)

Slip flow on a hydrogel surface was investigated in order to clarify the effect of drag reduction on the aqueous surface of living things. Thin-film flow along the hydrogel surface was measured by using a micro PIV (particle image velocimetry) system for comparison with theoretical velocity distribution which satisfied the non-slip condition on a solid surface. The slip flow on the hydrogel was found to be related to the degree of swelling and molecular weight of the hydrogel materials. This shows the possibility of a reduction in wall shear stress as a result of the decrease in the velocity gradient near a wall surface.

Kikuchi, K.; Mochizuki, O.

2014-06-01

248

Butt Joint Tool Commissioning  

SciTech Connect

ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt joining tool to improve its convenience of operation and provide all features necessary for production of butt joints by qualified personnel.

Martovetsky, N N

2007-12-06

249

From frictional fingers to stick slip bubbles  

NASA Astrophysics Data System (ADS)

Gas intrusion into wet porous/deformable/granular media occurs in a wide range of natural and engineered settings. Examples include hydrocarbon recovery, carbon dioxide geo-sequestration, gas venting in sediments and volcanic eruptions. In the case where the intruding gas is able to displace particles and grains, local changes in granular packing fraction govern the evolution of flow paths, resulting in complex pattern formation of the displacement flow. Here we investigate flow patterning as a compressed gas displaces a granular mixture confined in the narrow gap of a Hele-Shaw cell. We find a surprising variety of different pattern formation dynamics, and present a unified phase diagram of the flow morphologies we observe. This talk will focus on one particular transition the system undergoes: from frictional fingers to stick slip bubbles. We show that the frictional fluid flow patterns depend on granular mass loading and system elasticity, analogous to the behaviour of the well-known spring-block sliding friction problem.

Sandnes, Bjørnar; Jørgen Måløy, Knut; Flekkøy, Eirik; Eriksen, Jon

2014-05-01

250

Quantum phase slips in Josephson junction rings  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

251

Analysis of fluid injection-induced fault reactivation and seismic slip in geothermal reservoirs  

NASA Astrophysics Data System (ADS)

explore the issue of fault reactivation induced in enhanced geothermal systems by fluid injection. Specifically, we investigate the role of late stage activation by thermal drawdown. A Thermal-Hydrological-Mechanical simulator incorporating a ubiquitous joint constitutive model is used to systematically simulate the seismic slip of an embedded critically stressed strike-slip fault. We examine the effects of both pore pressure perturbation and thermal shrinkage stress on the magnitude of the resulting events and timing. We analyze the sensitivity of event magnitude and timing to changes in the permeability of the fault and fractured host, fracture spacing, injection temperature, and fault stress obliquity. From this we determine that (1) the fault permeability does not affect the timing of the events nor their size, since fluid transmission and cooling rate are controlled by the permeability of the host formation. (2) When the fractured medium permeability is reduced (from 10-13 to 10-16 m2), the timing of the event is proportionately delayed (by a corresponding 3 orders of magnitude). (3) Injection temperature only influences the magnitude but not the timing of the secondary thermal event. The larger the temperature differences between that of the injected fluid and the ambient rock, the larger the magnitude of the secondary slip event. (4) For equivalent permeabilities, changing the fracture spacing (10 m-50 m-100 m) primarily influences the rate of heat energy transfer and thermal drawdown within the reservoir. Smaller spacing between fractures results in more rapid thermal recovery but does not significantly influence the timing of the secondary thermal rupture.

Gan, Quan; Elsworth, Derek

2014-04-01

252

Pressure suit joint analyzer  

NASA Technical Reports Server (NTRS)

A measurement system for simultaneously measuring torque and angular flexure in a pressure suit joint is described. One end of a joint under test is held rigid. A torque transducer is pivotably supported on the other movable end of a joint. A potentiometer is attached to the transducer by an arm. The wiper shaft of the potentiometer is gripped by a reference arm that rotates the wiper shaft the same angle as the flexure of joint. A signal is generated by the potentiometer which is representative of the joint flexure. A compensation circuit converts the output of the transducer to a signal representative of joint torque.

Vykukal, H. C.; Webbon, B. W. (inventors)

1982-01-01

253

The Slip History and Source Statistics of Major Slow Slip Events along the Cascadia Subduction Zone from 1998 to 2008  

NASA Astrophysics Data System (ADS)

We estimate the time dependent slip distribution of 16 prominent slow slip events along the northern half of the Cascadia subduction zone from 1998 to 2008. We process continuous GPS data from the PBO, PANGA and WCDA networks from the past decade using GAMIT/GLOBK processing package. Transient surface displacements are interpreted as slip on the plate interface using the Extended Network Inversion Filter. Of these 16 events, 10 events are centered north of Puget Sound, 4 events are resolved around the Columbia River and 1 event is located near Cape Blanco. The February 2003 event is complex, extending from Portland to southern Vancouver Island. Other smaller events beneath Northern Vancouver Island, Oregon and Northern California are not well resolved because of the limited station coverage. We identify two characteristic segments based on the along-strike extent of individual transient slip events in northern Washington. One segment is centered around Port Angeles. Another segment is between the Columbia River and the southern end of Puget Sound. The propagation direction of slow slip events is variable from one event to the next. The maximum cumulative slip for these 16 events is ~ 27 cm, which is centered beneath Port Angeles. This indicates that the strain release by transient slip is not uniform along-strike. In northwestern Washington where cumulative slip is a maximum, the subduction zone bends along-strike and dip of the plate is lower compared to the north and south. We hypothesize that the geometry of the slab plays an important role for focusing transient strain release at this location along the subduction zone. We explore the relationship of source parameters of slow slip using our catalogue of 16 events. The estimated moment magnitude ranges between 6.1 and 6.7. The average stress drop of 0.06-0.1 MPa is nearly two orders of magnitude smaller than that found for normal earthquakes (1-10 MPa). Standard earthquakes follow a scaling relationship where rupture length is proportional to slip amplitude resulting in a nearly constant stress drop. Slow slip events display the similar scaling law up to a possible limit in slip amplitude. We also explore the relationship of event duration to other source parameters.

Gao, H.; Schmidt, D. A.

2008-12-01

254

Slipping zones from exhumed faults in dolostones (Borcola Pass Fault, Italian Southern Alps)  

NASA Astrophysics Data System (ADS)

Fault zones in limestones and dolostones represent significant seismogenic sources in many areas worldwide, including central Italy and the Italian Fore-Alps (e.g. Val di Noto 1693, estimated Mw = 6.9; Avezzano 1915, Mw = 6.7; Friuli 1976, Mw = 6.4; Irpinia 1980, Mw = 6.9; L'Aquila 2009, Mw = 6.3). Field and microstructural investigations of exhumed seismogenic fault zones and related fault rocks in carbonates are therefore important to document fault structure and the range of deformation processes active during the seismic cycle. The Borcola Pass Fault is a ca. N-S strike-slip branch of the Schio-Vicenza Line (a main lineament of the Italian Southern Alps) and is well exposed within a series of large dolostone quarries (Borcola Pass, Trento). Estimated depth and temperature conditions during faulting are ca. 1.6-1.7 km and 50°C. The fault zone consists of a > 80 m thick damage zone surrounding a 2-3 m thick fault core containing dolomitic fault rock lenses bounded by principal slip zones up to 10 cm thick. The damage zone is cut by three systems of secondary faults striking N-S, E-W and NW-SE. N-S and E-W striking faults reactivated inherited (Jurassic to Paleogene) regional-scale joints and have an average spacing between 0.2 to 0.5 m, whereas NW-SE striking faults were newly formed during post-Paleogene slip activity along the Borcola Pass Fault and the Schio-Vicenza Line. Both principal and secondary slip zones consist of cement-supported dolomitic cataclasites and dolomite-filled veins. Some slip zones contain a sub-centimetre thick vein-like cataclastic layer (Layer A) located immediately beneath the principal slip surface and above a cement-supported cataclasite (Layer B). Layer A is white in colour and consists of sub-rounded dolostone grains ranging between 300 ?m and 2.5 mm in size, suspended in a dolomitic cement. Layer B is grey in colour and consists of sub-angular dolostone grains ranging between 5 ?m and 1 cm in size within a dolomitic cement. According to image analysis investigations, Layer A has a lower 2-dimensional fractal dimension (D < 1) and better grain sorting than Layer B (D? 1.6). The boundary of Layer A towards the principal slip surface is cuspate-lobate and includes a 2-5 mm thick zoned ultracataclasite whereas towards Layer B the boundary is sharp and truncates clasts. Several injection veins depart from Layer A into Layer B. These microstructural data suggest that while grain fragmentation models (e.g. constrained comminution) can account for the clast size distribution found in Layer B (D ? 1.6), other physico-chemical (maybe coseismic) processes such as localized layer fluidization and grain sorting may result in the unusual textural characteristics, including the presence of injection veins, found in Layer A.

Fondriest, M.; Smith, S.; Di Toro, G.; Zampieri, D.

2011-12-01

255

23. View looking N with former Brooklyn ferry slip in ...  

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

23. View looking N with former Brooklyn ferry slip in foreground. Jet Lowe, photographer, 1982. - Brooklyn Bridge, Spanning East River between Park Row, Manhattan and Sands Street, Brooklyn, New York, New York County, NY

256

Slip, Trip, and Fall Prevention for Healthcare Workers.  

National Technical Information Service (NTIS)

Work-related slip, trip, and fall incidents can frequently result in serious disabling injuries that impact a healthcare employee's ability to do his or her job, often resulting in lost workdays, reduced productivity, expensive worker compensation claims,...

E. Dalsey J. Bell J. W. Collins V. Sublet

2010-01-01

257

Dislocation motion, constriction and cross-slip in fcc metals  

NASA Astrophysics Data System (ADS)

A Finnis/Sinclair-type interatomic potential for copper is used to examine the properties of dissociated screw dislocations in the face-centred cubic lattice. The critical stress for dislocation motion is found to be a sensitive function of the partial dislocation separation, with a lower limit at least 85% smaller than the Peierls stress. The constriction of Heidenreich-Shockley partials is modelled using an applied stress which interacts only with the edge Burgers vectors; recombination is not observed, but there is a critical separation below which the potential energy of the dislocation rises very rapidly. The classical model of cross-slip, in which the dislocation cannot leave its slip plane unless it is fully constricted, is found to be incorrect. Instead, cross-slip is possible at all partial separations, provided the driving stress is large enough. Finally, a new mechanism for cross-slip nucleation is described.

Duesbery, M. S.

1998-01-01

258

Frictional melting and stick-slip behavior in volcanic conduits  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

259

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

260

Should all unstable slipped capital femoral epiphysis be treated open?  

PubMed

Historically, in situ fixation has been considered the gold standard for the treatment of unstable slipped capital femoral epiphysis (SCFE). Open treatments can be considered in an attempt to improve outcome, primarily in an effort to decompress the hip or decrease residual deformity. For moderate and severe unstable slips, surgical hip dislocation followed by subcapital realignment has been proposed to address the metaphyseal prominence and prevent impingement. More recently, the natural history of mild slips after in situ pinning has also been questioned and new recommendations involving management with arthroscopic or mini open procedures have been proposed. The purpose of this manuscript is to review the current treatment options and to address the need for open treatments in unstable slipped capital femoral epiphysis. PMID:23764801

Lykissas, Marios G; McCarthy, James J

2013-01-01

261

Supershear Slip Pulse and Off-Fault Damage  

NASA Astrophysics Data System (ADS)

We extend a model of a two-dimensional self-healing slip pulse, propagating dynamically in steady-state with a slip-weakening failure criterion, to the supershear regime, in order to study the off-fault stressing induced by such a slip pulse and investigate features unique to the supershear range. Specifically, we show that there exists a non-attenuating stress field behind the Mach front which radiates high stresses arbitrarily far from the fault (practically this would be limited to distances comparable to the depth of the seismogenic zone), thus being capable of creating fresh damage or inducing Coulomb failure in known structures at large distances away from the main fault. We allow for both strike-slip and dip-slip failure induced by such a slip pulse by evaluating Coulomb stress changes on both known and optimally oriented structures. In particular we look for features of supershear slip pulse that could nucleate a slip-partitioning event at places where reverse or normal faults exist near a major strike-slip feature. We apply this model to study damage features induced during the 2001 Kokoxili (Kunlun) event in Tibet, for which it has been suggested that much of the rupture was supershear. We argue that an interval of simultaneous induced normal faulting is more likely due to a slip partitioning mechanism suggested previously than to the special features of supershear rupture. However, those features do provide an explanation for otherwise anomalous ground cracking at several kilometers from the main fault. In the big bend region of the San Andreas Fault there is active thrust faulting nearby which might be activated by a supershear event. The most vulnerable locations would be those for which part of the presumably seismogenic thrust surface is within ~15-20 km of the SAF, which (considering dip directions) may include the Pleito, Wheeler Ridge, Cucamonga, Clearwater, Frazier Mountain, Alamo, Dry Creek, Arrowhead, Santa Ana, Waterman Canyon, and San Gorgonio faults, and reverse or minor right-reverse sections of the Banning and San Jacinto fault systems. Many nearby strike slip segments could be vulnerable to the distant stressing too, at least if not oriented too close to perpendicular or parallel to the SAF. The degree of vulnerability has a strong dependence, to be documented, on directivity of the rupture on the SAF and orientation of the considered fault segment. We also compare the damage induced by supershear slip pulse with their sub-Rayleigh analogues to look for unique signature left behind by such slip pulses in terms of off-fault damage. We show that off-fault damage is controlled by the speed of the slip-pulse, scaled stress drop, and principal stress orientation of the pre-stress field. We also make some estimates of fracture energy which, for a given net slip and dynamic stress drop, is lower than for a sub-Rayleigh slip pulse, because part of the energy fed by the far-field stress is radiated back along the Mach fronts.

Bhat, H. S.; Dmowska, R.; King, G.; Klinger, Y.; Rice, J. R.

2005-12-01

262

Multiline Tow Cable Assembly Including Swivel and Slip Ring.  

National Technical Information Service (NTIS)

This patent application discloses a multiline tow cable assembly including swivel area components and slip ring components. The swivel area components include a rotor member connected to an external housing, at least one contact member formed within the r...

M. R. Williams

1998-01-01

263

Slip ring experience in long duration space applications  

NASA Technical Reports Server (NTRS)

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.

Phinney, Damon D.

1986-01-01

264

M -6 laboratory earthquakes driven by aseismic slip (Invited)  

NASA Astrophysics Data System (ADS)

We report observations of the interaction between slow, predominantly aseismic slip and small earthquakes in a suite of laboratory experiments conducted on a 1.5 m granite block. The rupture areas of these M -6 laboratory-generated earthquakes are typically less than 0.1% of the total fault area and are completely contained within the interior of the 2.0 by 0.4 m laboratory fault. The ground motions produced by these extremely small seismic events are recorded with an array of piezoelectric sensors which have been calibrated against the radiated waves from ball impact. Their seismic source spectra are consistent with common earthquake scaling laws derived from observations of larger natural earthquakes. However, these small events differ significantly from typical earthquakes in that they never occur on their own as a slipping patch surrounded by locked fault. Instead, they only occur in response to larger-scale aseismic slip of the surrounding fault, at aseismic slip rates greater than ~50 ?m/s. We detect this aseismic slip on the surface trace of the fault with an array of slip sensors, and we infer aseismic slip within the sample from local stress changes detected with an array of strain gages and lower frequency ground deformation detected with the piezoelectric sensors. We find that the spatial dimensions of the M -6 earthquakes (~ 10 mm) are much smaller than our estimates of h*, the minimum length scale for instability that we would expect based on the laboratory conditions (5 MPa normal stress, and 10s of ?m surface roughness). Our results indicate that locally strong fault patches can slip unstably and radiate seismic waves even if they are significantly smaller than h* as long as they are rapidly stressed by aseismic slip of neighboring fault sections. In most of the seismogenic crust we would expect that h* is small compared to the rupture area of earthquakes. Since seismic coupling is low on the laboratory fault and h* is large relative to the rupture areas of potential earthquakes, the interactions between aseismic and seismic slip observed in the laboratory may be similar to processes occurring on plate interfaces with low seismic coupling and relatively large h* such as creeping fault sections that predominantly produce small repeating earthquakes or the deep extent of fault zones where relative fault motion occurs as slow slip accompanied by tremor and low frequency earthquakes.

Mclaskey, G.; Kilgore, B. D.; Beeler, N. M.; Lockner, D. A.

2013-12-01

265

Repair of central slip avulsions using Mitek Micro Arc bone anchors. An in vitro biomechanical assessment.  

PubMed

In this study we evaluated the pullout strength of the Mitek Micro Arc anchor for the reconstruction of central slip avulsions at the proximal interphalangeal joint of the finger. Forty paired fresh frozen cadaver fingers were randomized into treatment (anchor) and control groups (horizontal mattress repair) and subjected to tensile loading to failure. The mean (SD) failure loads of the repairs were: Mitek repair group 22.3 (4.7) N, and control group 24.7 (5.5) N. There were no statistically significant differences between the failure loads or the failure mechanisms of the two repairs. The pullout strength of the isolated anchor-bone complex was evaluated by refitting five anchors with stainless steel wire. The mean failure load of the isolated anchor was 400% higher than the tendon-suture-anchor complex, indicating that the weakest link of the system is not the bone-anchor interface. PMID:10672803

Cluett, J; Milne, A D; Yang, D; Morris, S F

1999-12-01

266

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

Microsoft Academic Search

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

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

2001-01-01

267

Factors affecting slip melting point of palm oil products  

Microsoft Academic Search

The effect of different factors affecting the slip melting point of palm oil has been evaluated. The most important factor\\u000a appears to be the difference in tempering temperatures. The influence of different tempering temperatures on slip point values\\u000a is, however, dependent on the nature of the sample. For hydrogenated oils and for some high-melting palm stearins, tempering\\u000a has no effect.

K. G. Berger; W. L. Siew; Flingoh C. H. OH

1982-01-01

268

Reference frame analysis of a slip energy recovery system  

Microsoft Academic Search

Until the late 1970s the performance of a slip energy recovery system of an induction motor was predicted analytically by means of steady-state power balance relationships. Here, reference frame theory is used to establish the equations which can be used to predict adequately the dynamic and steady-state performance of a slip energy recovery system. The steady-state performance as predicted from

P. C. Krause; O. Wasynczuk; M. S. Hildebrandt

1988-01-01

269

Surface mobility and slip of polybutadiene melts in shear flow  

Microsoft Academic Search

Surface mobility and wall slip of entangled polybutadiene melts were studied with attenuated-total-reflectance infrared spectroscopy at stresses characteristic of the sharkskin, spurt, and melt-fracture regimes. Small-scale slip, accompanied by an apparent decrease in transverse mobility, occurs in the sharkskin regime, but at a stress above the visual onset of sharkskin in capillary viscometry. Simulations cannot distinguish between a cohesive mechanism

Geoffrey M. Wise; Morton M. Denn; Alexis T. Bell; Jimmy W. Mays; Kunlun Hong; Hermis Iatrou

2000-01-01

270

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

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.

Shekhar, S.

1997-03-01

271

Slip, swim, mix, pack: Fluid mechanics at the micron scale  

Microsoft Academic Search

This thesis is devoted to fluid behavior at the micrometer length scale and considers four different problems. We first address the topic of the no-slip boundary condition in Newtonian liquids. After reviewing the field, we present models for apparent slip in three distinct experimental settings: Steady pressure-driven flow over heterogeneous surfaces, unsteady drainage flow over surface-attached bubbles, and flow of

Eric Lauga

2005-01-01

272

Effective Slip over Superhydrophobic Surfaces in Thin Channels  

Microsoft Academic Search

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a microscopic texture. Recent work has focused on specific cases, such as arrays of pillars or grooves, 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

François Feuillebois; Martin Z. Bazant; Olga I. Vinogradova

2009-01-01

273

Optical Slip Rings for Home Security High-Definition Cameras  

Microsoft Academic Search

A new optical transmission slip ring which has a light pipe at the center of rotation in order to provide a stable 1.25 Gbps high-speed transmission line for high-definition video. This design, using a conventional slip ring, has made it possible to realize the development of a 360-degree endless panning home security camera that supports the transmission of high-definition video

T. Aizawa; M. Sakai; S. Toguchi; K. Hirohashi

2007-01-01

274

An implementation of no-slip boundary conditions in DPD  

Microsoft Academic Search

We report an implementation of the no-slip boundary condition in the modeling of solid boundaries by dissipative particle dynamics (DPD) method. Stimulated by a model for several types of solid boundaries, we develop an implementation that satisfies no-slip boundary condition with practically no-density distortion near the boundaries. The model is implemented to simulate the planar Poiseuille and Couette flows, as

Duc Duong-Hong; Nhan Phan-Thien; Xijun Fan

2004-01-01

275

Dynamic Mechanochemistry of Seismic Slip Nano Spherules Lubrication  

Microsoft Academic Search

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

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

2007-01-01

276

Temperature dependence of atomic-scale stick-slip friction.  

PubMed

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. PMID:20867399

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

2010-06-25

277

Strike-slip motion and double ridge formation on Europa  

Microsoft Academic Search

There is abundant observational evidence for strike-slip displacement on the surface of Europa. Strike-slip motion between crustal blocks produces shear heating and an increase in temperature. We model the shear heating within the ice crust using a two-dimensional, finite difference formulation, with a near-surface brittle layer of constant specified thickness and a Newtonian ductile layer beneath. We obtain a maximum

Francis Nimmo; Eric Gaidos

2002-01-01

278

Distribution of strike-slip faults on Europa  

Microsoft Academic Search

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

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

2000-01-01

279

Modelling Paleoearthquake Slip Distributions using a Gentic Algorithm  

NASA Astrophysics Data System (ADS)

Along the Sunda trench, the annual growth rings of coral microatolls store long term records of tectonic deformation. Spread over large areas of an active megathrust fault, they offer the possibility of high resolution reconstructions of slip for a number of paleo-earthquakes. These data are complex with spatial and temporal variations in uncertainty. Rather than assuming that any one model will uniquely fit the data, Monte Carlo Slip Estimation (MCSE) modelling produces a catalogue of possible models for each event. From each earthquake's catalogue, a model is selected and a possible history of slip along the fault reconstructed. By generating multiple histories, then finding the average slip during each earthquake, a probabilistic history of slip along the fault can be generated and areas that may have a large slip deficit identified. However, the MCSE technique requires the production of many hundreds of billions of models to yield the few models that fit the observed coral data. In an attempt to accelerate this process, we have designed a Genetic Algorithm (GA). The GA uses evolutionary operators to recombine the information held by a population of possible slip models to produce a set of new models, based on how well they reproduce a set of coral deformation data. Repeated iterations of the algorithm produce populations of improved models, each generation better satisfying the coral data. Preliminary results have shown the GA to be capable of recovering synthetically generated slip distributions based their displacements of sets of corals faster than the MCSE technique. The results of the systematic testing of the GA technique and its performance using both synthetic and observed coral displacement data will be presented.

Lindsay, Anthony; Simão, Nuno; McCloskey, John; Nalbant, Suleyman; Murphy, Shane; Bhloscaidh, Mairead Nic

2013-04-01

280

Dislocation Cross-Slip in Nanocrystalline fcc Metals  

NASA Astrophysics Data System (ADS)

Constant strain rate molecular dynamics simulations of nanocrystalline Al demonstrate that a significant amount of dislocations that have nucleated at the grain boundaries, exhibit cross-slip via the Fleischer mechanism as they propagate through the grain. The grain boundary structure is found to strongly influence when and where cross-slip occurs, allowing the dislocation to avoid local stress concentrations that otherwise can act as strong pinning sites for dislocation propagation.

Bitzek, E.; Brandl, C.; Derlet, P. M.; van Swygenhoven, H.

2008-06-01

281

Variable slip coefficient in binary lattice Boltzmann models  

NASA Astrophysics Data System (ADS)

We present a new method in order to obtain variable slip coefficient in binary lattice Boltzmann models to simulate gaseous flows. We present the Boundary layer theory. We study both the single-and multi-fluid BGK-type models as well. The boundary slip and the Knudsen layer are analyzed in detail. Benchmark simulations are carried out in order to compare the analytical derivation with the numerical results. Excellent agreement is found between the two analytical formalism and the numerical simulations.

Szalmás, Lajos

2008-12-01

282

Strike-slip duplexing on Jupiter's icy moon Europa  

Microsoft Academic Search

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

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

2000-01-01

283

Gain-scheduled wheel slip control in automotive brake systems  

Microsoft Academic Search

A wheel slip controller is developed and experimentally tested in a car equipped with electromechanical brake actuators and a brake-by-wire system. A gain scheduling approach is taken, where the vehicle speed is viewed as a slowly time-varying parameter and the model is linearized about the nominal wheel slip. Gain matrices for the different operating conditions are designed using an LQR

Tor A. Johansen; Idar Petersen; Jens Kalkkuhl; Jens Ludemann

2003-01-01

284

Foreshocks during the nucleation of stick-slip instability  

USGS Publications Warehouse

We report on laboratory experiments which investigate interactions between aseismic slip, stress changes, and seismicity on a critically stressed fault during the nucleation of stick-slip instability. We monitor quasi-static and dynamic changes in local shear stress and fault slip with arrays of gages deployed along a simulated strike-slip fault (2?m long and 0.4?m deep) in a saw cut sample of Sierra White granite. With 14 piezoelectric sensors, we simultaneously monitor seismic signals produced during the nucleation phase and subsequent dynamic rupture. We observe localized aseismic fault slip in an approximately meter-sized zone in the center of the fault, while the ends of the fault remain locked. Clusters of high-frequency foreshocks (Mw?~??6.5 to ?5.0) can occur in this slowly slipping zone 5–50?ms prior to the initiation of dynamic rupture; their occurrence appears to be dependent on the rate at which local shear stress is applied to the fault. The meter-sized nucleation zone is generally consistent with theoretical estimates, but source radii of the foreshocks (2 to 70?mm) are 1 to 2 orders of magnitude smaller than the theoretical minimum length scale over which earthquake nucleation can occur. We propose that frictional stability and the transition between seismic and aseismic slip are modulated by local stressing rate and that fault sections, which would typically slip aseismically, may radiate seismic waves if they are rapidly stressed. Fault behavior of this type may provide physical insight into the mechanics of foreshocks, tremor, repeating earthquake sequences, and a minimum earthquake source dimension.

McLaskey, Gregory C.; Kilgore, Brian D.

2013-01-01

285

Jointness A Selected Bibliography.  

National Technical Information Service (NTIS)

To assist researchers in a better understanding of how the United States armed services work together, the U.S. Army War College Library presents Jointness: A Selected Bibliography. A revised and updated version of our earlier bibliographies on jointness,...

2000-01-01

286

Large displacement spherical joint  

DOEpatents

A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2002-01-01

287

Joints and Movements.  

National Technical Information Service (NTIS)

The report contains an explanation of anatomical concepts of joints and movements necessary in biomedical and physical therapy education. Upon completion of pamphlet, reader will be able to: (1) identify movements at any joint in the human body, (2) diffe...

P. Jacoby-Lockhart H. B. Slotnick

1979-01-01

288

Stick-slip statistics of a physical slider block model  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

289

Surface mobility and slip of polybutadiene melts in shear flow  

SciTech Connect

Surface mobility and wall slip of entangled polybutadiene melts were studied with attenuated-total-reflectance infrared spectroscopy at stresses characteristic of the sharkskin, spurt, and melt-fracture regimes. Small-scale slip, accompanied by an apparent decrease in transverse mobility, occurs in the sharkskin regime, but at a stress above the visual onset of sharkskin in capillary viscometry. Simulations cannot distinguish between a cohesive mechanism and a lubrication mechanism that might follow from a stress-induced phase transition, but an adhesive failure seems to be excluded. The near-surface length scale is of the order of four to six times the equilibrium root-mean-square end-to-end distance, and the estimated slip velocity is insensitive to molecular weight. Strong slip occurs in the spurt regime, either at the wall or within one radius of gyration. Substantial apparent slip occurs with a fluorocarbon surface, but the mechanism does not appear to be an adhesive failure; there seems to be a substantial decrease in the friction coefficient of chains over a distance of order 300 nm or more from the fluorocarbon surface, and the transverse chain mobility in this region appears to be enhanced rather than retarded. Overall, the results of this study indicate that the influence of the wall extends farther into the sheared melt than would be expected from the chain dimensions, except in the case of strong slip. (c) 2000 Society of Rheology.

Wise, Geoffrey M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Denn, Morton M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Bell, Alexis T. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Mays, Jimmy W. [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States); Hong, Kunlun [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States); Iatrou, Hermis [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)

2000-05-01

290

A generating mechanism for apparent fluid slip in hydrophobic microchannels  

NASA Astrophysics Data System (ADS)

Fluid slip has been observed experimentally in micro- and nanoscale flow devices by several investigators [e.g., Tretheway and Meinhart, Phys. Fluids 14, L9 (2002); Zhu and Granik, Phys. Rev. Lett. 87, 096105 (2001); Pit et al., Phys. Rev. Lett. 85, 980 (2000); and Choi et al., Phys. Fluids 15, 2897 (2003)]. This paper examines a possible mechanism for the measured fluid slip, for water flowing over a hydrophobic surface. We extend the work of Lum et al. [J. Phys. Chem. B 103, 4570 (1999)], Zhu and Granick [Phys. Rev. Lett. 87, 096105 (2001)], Granick et al. [Nature Materials 2, 221 (2003)], and de Gennes [Langmuir 18, 3413 (2002)], who suggest slip develops from a depleted water region or vapor layer near a hydrophobic surface. By modeling the presence of either a depleted water layer or nanobubbles as an effective air gap at the wall, we calculate slip lengths for flow between two infinite parallel plates. The calculated slip lengths are consistent with experimental values when the gas layer is modeled as a continuum and significantly higher when rarefied gas conditions are assumed. The results suggest that the apparent fluid slip observed experimentally at hydrophobic surfaces may arise from either the presence of nanobubbles or a layer of low density fluid at the surface.

Tretheway, Derek C.; Meinhart, Carl D.

2004-05-01

291

CYCLIC MOTION ENCODING FOR ENHANCED MR VISUALIZATION OF SLIP INTERFACES  

PubMed Central

Purpose To develop and test an MRI-based method for assessing the mechanical shear connectivity across tissue interfaces with phantom experiments and in vivo feasibility studies. Materials and Methods External vibrations were applied to phantoms and tissue and the differential motion on either side of interfaces within the media was mapped onto the phase of the MR images using cyclic motion encoding gradients. The phase variations within the voxels of functional slip interfaces reduced the net magnitude signal in those regions, thus enhancing their visualization. A simple two-compartment model was developed to relate this signal loss to the intravoxel phase variations. In vivo studies of the abdomen and forearm were performed to visualize slip interfaces in healthy volunteers. Results The phantom experiments demonstrated that the proposed technique can assess the functionality of shear slip interfaces and they provided experimental validation for the theoretical model developed. Studies of the abdomen showed that the slip interface between the small bowel and the peritoneal wall can be visualized. In the forearm, this technique was able to depict the slip interfaces between the functional compartments of the extrinsic forearm muscles. Conclusion Functional shear slip interfaces can be visualized sensitively using cyclic motion encoding of externally applied tissue vibrations.

Mariappan, Yogesh K; Glaser, Kevin J; Manduca, Armando; Ehman, Richard L

2010-01-01

292

Fault slip during a glacial cycle  

NASA Astrophysics Data System (ADS)

Areas affected by glacial isostatic adjustment (GIA) generally show uplift after deglaciation. These regions are also characterized by a moderate past and present-day seismicity, at seismic moment release rates that exceed those expected under stable tectonic conditions. Several faults have been found in North America and Europe, which have been activated during or after the last deglaciation. Large-magnitude earthquakes have generated fault offsets of up to 120 m. Due to the recent melting of Greenland and Antarctic ice sheets, an understanding of the occurrence of these earthquakes is important. With a new finite-element model, we are able to estimate, for the first time, fault slip during a glacial cycle for continental ice sheets. A two-dimensional earth model based on former GIA studies is developed, which is loaded with a hyperbolic ice sheet. The fault is able to move in a stress field consisting of rebound stress, tectonic background stress, and lithostatic stress. The sensitivity of this fault is tested regarding lithospheric and crustal thickness, viscosity structure of upper and lower mantle, ice-sheet thickness and width, and fault parameters including coefficient of friction, depth, angle and location. Fault throws of up to 30 m are obtained using a fault of 45° dipping below the ice sheet centre. The thickness of the crust is one of the major parameters affecting the total fault throw, e.g. higher values for a thinner crust. Most faults start to move close to the end of deglaciation, and movement stops after one thrusting/reverse earthquake. However, certain conditions may also lead to several fault movements after the end of glaciations.

Steffen, Rebekka; Wu, Patrick; Steffen, Holger; Eaton, Dave

2013-04-01

293

On the application of no-slip lateral boundary conditions to 'coarsely' resolved ocean models  

Microsoft Academic Search

The application of no-slip boundary conditions to ocean models is reformulated using Law of the Wall and Monin-Obhukov Similarity theory. The proposed boundary condition formulation is implemented in the MITgcm. Comparisons with classically formulated free-slip and no-slip cases shows the results are somewhat between the two cases, but generally closer to the free-slip outcomes.

Bruno Deremble; Andrew Mcc. Hogg; Pavel Berloff; W. K. Dewar

2011-01-01

294

The identification of factors in the systematic evaluation of slip prevention on icy surfaces  

Microsoft Academic Search

Slips and falls on icy roads often result in fractures or sprains and is a major problem in Nordic countries. Walking trials by 25 subjects wearing four types of winter shoes on five different icy walking surfaces provided subjective and objective measures of tendency to slip and number of slips, respectively. Since friction is a major determinant of a slip,

John Abeysekera; Chuansi Gao

2001-01-01

295

Scaling of micro-slip in tangentially loaded rock contact  

NASA Astrophysics Data System (ADS)

A dry contact between randomly rough surfaces is examined which is loaded in normal and tangential direction. If the tangential load is below the friction force, no macroscopic tangential movement takes place. Nevertheless, some part of the contact area will be in sticking and some will be in sliding state depending on the local stress configuration. This effect will be called micro-slip. The maximum value of this micro-slip is reached when the last contacting spot goes into sliding state. The maximum micro-slip is a core characteristic of the contact problem. It appears in rock friction laws as a characteristic length parameter, which is often empirically determined. It can be interpreted as the characteristic size of micro-contacts appearing in rate-and-state friction theory (1). The scaling behavior of this characteristic length parameter is not yet clarified (2). It is of special interest for geophysical applications, where laboratory experiments and real systems differ in size by several orders of magnitude. In former works many suggestions have been made on the scaling context of this length parameter: surface roughness, total slip length, shear strain and system size ((1),(3),(4),(5)) are some of the proposed connected parameters. We recently presented a theoretical estimation of the maximum micro-slip for randomly rough surfaces, which is based on the iterrelation of the normal and tangential contact problem. Using recent finding concerning the normal contact problem of randomly rough surfaces (6) we were able to suggest a scaling law for the maximum micro-slip. It suggests a power-law scaling with the present normal force (7). A numerical contact model using the boundary element method was implemented for comparison, both results coincide perfectly. In addition we will present experiments with rock-rock contact in the preface of instable sliding. The set-up is a single-block slider model. From high resolution measurements, we were able to capture the micro-slip preceding a global slip event in a stick-slip regime, including the maximum micro-slip. 1. Dieterich, James H. Time Dependent Friction and the Mechanics of Stick-Slip. 1978, Pure and Applied Geophysics, Vol. 116, pp. 790-806. 2. Scholz, C. H. The Critical Slip Distance for Seismic Faulting. 22/29, 1988, Nature, Vol. 336, pp. 761-763. 3. Ohnaka, M. A constitutive scaling law and a unified comprehension for frictional slip failure, shear fracture of intact rock, and earthquake rupture.B2, 2003, Journal of Geophysical Research: Solid Earth, Vol. 108, p. 2080. 4. Marone, C. and Kilgore, B. Scaling of critical slip distance for seismic faulting with shear strain in fault zones. 1993, Nature, Vol. 362, pp. 618-621. 5. Marone, C. and Cox, S.J.D. Scaling of Rock Friction Constitutive Parameters: The Effects of Surface Roughness and Cumulative Offset on Friction of Gabbro. 1994, Pure and Applied Geophysics, Vol. 143, pp. 359-385. 6. Pohrt, R. and Popov, V.L. Normal Contact Stiffness of Elastic Solids with Fractal Rough Surfaces. 2012, Physical Review Letters, Vol. 108, p. 104301. 7. Grzemba, B., et al. Maximum micro-slip in tangential contact of randomly rough self-affine surfaces. 2014, Wear, Vol. 309, pp. 256-258.

Grzemba, Birthe; Pohrt, Roman; Teidelt, Elena; Popov, Valentin L.

2014-05-01

296

Kinematically Coupled Strike-Slip and Normal Faults in the Lake Mead Strike-Slip Fault System, Southeast Nevada  

Microsoft Academic Search

The Lake Mead fault system consists of a ~95 km long, northeast-trending zone of strike-slip faults of Miocene age that accommodate a total left-lateral offset of 20-65 km. We use a combination of detailed field mapping and numerical modeling to show that a previously unnamed left-lateral strike-slip segment of the Lake Mead fault system and a dense cluster of dominantly

S. A. Kattenhorn; S. T. Marshall; M. L. Cooke

2008-01-01

297

What can friction tell us about shallow megathrust slip behavior?  

NASA Astrophysics Data System (ADS)

In subduction zones, the updip propagation of great earthquake ruptures on plate boundary megathrusts is currently one of the most important questions in earth science, primarily because rupture that approaches the surface causes seafloor displacement, resulting in enormous tsunamis. Moreover, the extent of updip rupture propagation is a key factor in defining the magnitude of the earthquake itself. Within the depth limits of the seismogenic zone, velocity-weakening frictional behavior is essential for the nucleation of large-magnitude earthquake rupture. Results of friction experiments at low slip velocities (~10-6-10-4 m/s) have suggested that velocity-weakening tends to occur in frictionally strong materials (typically non-clay), which may act as asperities on fault surfaces. However, the role of frictional strength and velocity dependence in controlling the extent of rupture propagation beyond the updip limit of the seismogenic zone is still unclear. Low to high-velocity friction experiments have provided insights into fault strength evolution over slip velocities spanning ~10 orders of magnitude, from plate convergence rates to coseismic slip rates. Results using primarily non-clay materials typically exhibit high friction at low velocities that progressively weakens at higher velocities (velocity-weakening), becoming nearly frictionless at coseismic slip rates [Di Toro et al., 2011]. However, the shallow near-trench regions of subduction zones are typically rich in clay minerals which are weak (friction coefficient ? ~0.4) and velocity-strengthening at slip rates < 10-3 m/s. A compilation of friction experiments using samples from the Nankai Trough region offshore Japan obtained by scientific ocean drilling shows that this material exhibits such behavior at low to intermediate slip velocities. However, after reaching peak values at ~10-2 m/s, these materials also exhibit a precipitous drop in friction toward near-zero values at coseismic slip rates. This suggests that all geologic materials, regardless of composition, are extremely weak when coseismic slip rates are enforced. Therefore, the likelihood of near-trench rupture propagation in subduction zones depends critically on whether slip can reach velocities ? ~10-2 m/s, where dynamic weakening becomes dominant. This depends on whether the propagating earthquake rupture can overcome the overall strength of the fault gouge and/or velocity-strengthening behavior at low to intermediate slip rates. We discuss here the possibility of near-trench earthquake rupture at Nankai and other subduction zones on the basis of laboratory friction measurements.

Ikari, M.; Kopf, A.; Hirose, T.

2012-12-01

298

Reactivated strike slip faults: examples from north Cornwall, UK  

NASA Astrophysics Data System (ADS)

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 relative age of the two strike-slip movements is (1) the first formed tip cracks associated with right-lateral slip are deformed, whereas the tip cracks formed during left-lateral slip show no deformation; (2) some of the tip cracks associated with right-lateral movement show left-lateral reactivation; and (3) left-lateral displacement is commonly recorded at the tips of dominantly right-lateral faults. The orientation of the tip cracks to the main fault is 30-70° clockwise for right-lateral slip, and 20-40° counter-clockwise for left-lateral slip. The structure formed by this process of strike-slip reactivation is termed a "tree structure" because it is similar to a tree with branches. The angular difference between these two groups of tip cracks could be interpreted as due to different stress distribution (e.g., transtensional/transpressional, near-field or far-field stress), different fracture modes or fractures utilizing pre-existing planes of weakness. Most of the d- x profiles have similar patterns, which show low or negative displacement at the segment fault tips. Although the d- x profiles are complicated by fault segments and reactivation, they provide clear evidence for reactivation. Profiles that experienced two opposite slip movements show various shapes depending on the amount of displacement and the slip sequence. For a larger slip followed by a smaller slip with opposite sense, the profile would be expected to record very low or reverse displacement at fault tips due to late-stage tip propagation. Whereas for a smaller slip followed by larger slip with opposite sense, the d- x profile would be flatter with no reverse displacement at the tips. Reactivation also decreases the ratio of dmax/ L since for an original right-lateral fault, left lateral reactivation will reduce the net displacement ( dmax) along a fault and increase the fault length ( L). Finally we compare Crackington Haven faults with these in the Atacama system of northern Chile. The Salar Grande Fault (SGF) formed as a left-lateral fault with large displacement in its central region. Later right-lateral reactivation is preserved at the fault tips and at the smaller sub-parallel Cerro Chuculay Fault. These faults resemble those seen at Crackington Haven.

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

2001-10-01

299

Electromagnetic emissions during seismic nucleation phase of stick-slips  

NASA Astrophysics Data System (ADS)

I. Introduction The size of seismic nucleation is determined by the characteristic wavelength of slip surface topography, and some scaling laws are derived from it (Ohnaka and Shen, 1999). Alternative characteristic wavelength should be introduced for natural faults because they are associated with layers of fault gouge. Riedel shear will be an equivalent since it is a characteristic structure inside fault zones. II. Method of stick- slip experiments Experimental apparatus: tri-axial apparatus. Samples: granite and gabbro cylinders of 20mmx40mm. Precut surface: 50 degree against sample axis and mirror-finished. Simulated fault gouge: quartz and gabbro powder of 0.25g. Sensors: strain gauges for measurements of axial stress and slip distance as well as three shear strain gauges pasted along a slip surface, three pairs of electrodes for measurement of triboelectric potentials. Data acquisition: continuously and synchronously at 2MHz. Experimental procedure: loading of axial stress after holding at confining pressure of 80-180 MPa and shear stress at 250 MPa during 0.1-1 hour for compaction of gouge. III. Experimental results 1) Stick-slips on bare surfaces Fluctuations of the electrode potentials during main stick-slip events are 55-180mV. Gabbro and granite samples do not show significant differences in magnitude of electrode potential. Any experimental runs were not associated with nucleation phases. Prior to main stick-slip events spike-like signals of electrode potentials were sometimes found synchronously with very small stress drops less than 1MPa. The amplitudes are less than 30mV, and they decayed exponentially. 2) Stick-slips with fault gouge Stress drops and fluctuations of electrode potentials at main stick-slip events are 7-400 MPa, 17-200mV+. Significant differences in fluctuations of electrode potentials were not found between granite and gabbro samples. About 30% of all experimental runs were associated with a nucleation phase. Slip distance, stress drop, duration and the maximum fluctuation of electrode potentials were 0.02mm, 14MPa, 0.3sec and 20mV in an experimental run, and the latter three were 3.5MPa, 0.35sec and 4mV in another run. Three pairs of strain gauges recorded the initial site and its propagation of a seismic nucleation. The potentials of three pairs of electrodes also fluctuated synchronously. The pulse-like electrode signals were sometimes found also for these experiments. IV. Discussions and conclusions 1) The reason why the stick-slips on bare surfaces were not associated with a nucleation phase is attributed to mirror-finished smooth and flat precut surfaces. 2) Irrespective of granite or gabbro powders of fault gouge, there were not significant differences in magnitude of pulse-like fluctuations of electrode potentials. This is the case for main stick-slip events. These indicate that the causes of the electric signals are not piezoelectric effect but triboelectricity and/or fracto-emission. 3) Since the fluctuations of electrode potentials are synchronous with the initiation and propagation of a nucleation, the former is attributed to the latter. 4) It is very likely that nucleation is quasi-static slip on a Riedel shear because the length of a nuclei estimated from slip during nucleation phases is the same order as the length of Riedel shears.

Onuma, K.; Otsuki, K.

2008-12-01

300

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

301

Rupture history of the 2009 L'Aquila (Italy) earthquake from non-linear joint inversion of strong motion and GPS data  

Microsoft Academic Search

We image the rupture history of the 2009 L'Aquila (central Italy) earthquake using a nonlinear joint inversion of strong motion and GPS data. This earthquake ruptured a normal fault striking along the Apennines axis and dipping to the SW. The inferred slip distribution is heterogeneous and characterized by a small, shallow slip patch located up-dip from the hypocenter (9.5 km

A. Cirella; A. Piatanesi; M. Cocco; E. Tinti; L. Scognamiglio; A. Michelini; A. Lomax; E. Boschi

2009-01-01

302

Nucleation and triggering of earthquake slip: effect of periodic stresses  

USGS Publications Warehouse

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.

Dieterich, J. H.

1987-01-01

303

Slip Running Reconnection in Magnetic Flux Ropes  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

304

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

305

A comparison of slip rate, recurrence interval, and slip per event on several well-characterized faults (Invited)  

NASA Astrophysics Data System (ADS)

Rapid growth in the application of LiDAR and other modern geodetic techniques has led to an explosion in the number of micro-geomorphic offsets along faults that can be interpreted as displacement in one or several earthquakes. As a result of this new data there are an increasing number of places along faults for which data are available for the slip rate (based on the dated offset of a feature that is old enough to average out the seismic cycle), recurrence interval (based on a representative number of dated paleo-earthquakes), and slip per event (based on an adequate sample of micro-geomorphic or 3D-excavated offsets). Because these three datasets are largely independent, but related by accumulation and release of strain across the fault, comparing them can provide insight into how faults balance size and frequency of earthquakes. We discuss several examples of faults with closely co-located slip rate, recurrence interval, and slip per event data, including the Ana River fault, a small normal fault in Central Oregon, and portions of the San Andreas fault, the principal plate boundary fault in California. The Ana River fault offsets more than 11 Pleistocene shorelines different amounts that we have measured using a combination of LiDAR, ground-based surveying, and a DEM generated from a USGS topographic map with 5 foot contours. The ages of ~10 paleo-earthquakes are determined from trenches and other exposures into deep-water lacustrine deposits that contain ~50 dated volcanic ashes. The long-term slip rate, 0.05 mm/yr, is known from the total offset of dated late Pliocene basalts. We also use new data from the Santa Cruz segment of the northern San Andreas fault (NSAF) and the southern San Andreas fault (SSAF: Parkfield to Bombay Beach). On the NSAF, earthquakes in 1838, 1890, and 1906 have a total slip of 4 - 6 m while the slip rate (17 mm/yr) suggests it would take 2 - 3 centuries to accumulate this much strain. Data for the SSAF, which have recently been compiled for UCERF-3, include 12 sites with recurrence intervals, hundreds of micro-geomorphic offsets, including at least 7 places with closely-spaced progressively larger offsets that allow one to estimate the average slip per event, and slip rate estimates that vary from about 34 to 12 mm/yr, decreasing from Parkfield to San Gorgonio Pass and then increasing to the southern end of the SSAF. In general the 3 types of data are reasonably consistent (i.e. slip rate (mm/yr) = slip per event (mm) X recurrence interval (1/yr)). Recurrence intervals seem to be more variable than displacements, although displacement variability may be biased by difficulty resolving small offsets with geomorphic markers. Assuming slip rate is constant through time, in places where (or periods of time when) there are inconsistencies between the three parameters it appears to be due to the intervals between earthquakes varying more than displacements, i.e. short intervals are not associated with small enough displacements and long intervals do not yield unusually large displacements. Similarly, as the SSAF changes slip rate along strike the recurrence interval varies more than the size of slip events.

Weldon, R. J.; Lippoldt, R. C.; Scharer, K.; Streig, A. R.; Langridge, R. M.; Madugo, C. M.; Biasi, G. P.; Dawson, T. E.

2013-12-01

306

Premonitory Acoustic Emissions and Slip Nucleation during Stick Slip Experiments in Naturally and Smooth (Saw-cut) Faulted Westerly Granite  

NASA Astrophysics Data System (ADS)

We compare premonitory microcracking and stick slip events for two Westerly granite samples containing a natural and a saw-cut (smooth) fault. The samples were 190.5 mm in length, and 76.2 mm in diameter. Stick slip events were induced by triaxial loading at 150 MPa confining stress, at a constant strain rate of 5 x10-6 s-1. One sample contained a polished saw-cut fracture (roughened using 220 grit), at 30 degrees to the sample axis. The second contained a natural fracture that had been previously (quasi-statically) induced by triaxial loading. The experiments were monitored using a novel continuous Acoustic Emission (AE) recorder. Three stick slip events were induced on the saw-cut sample, accompanied by fewer than 100 located AEs. Frictional coefficients were 0.48, 0.51, and 0.59 respectively. The first motion of each stick slip was recorded as a large-amplitude AE signal. These located on the saw-cut fault plane, and represent nucleation sites of the stick-slip events. Nucleation location varied between events, probably being controlled by stress heterogeneities or surface conditions on the fault. Prior to the first slip, AE located at the fault tips, with a small amount of premonitory creep. (Approximately 1 cm of each fault tip was removed when the fault was cut and these areas were packed with sand.) AE Source mechanisms were calculated using Moment Tensor inversion, and correspond to compressive sources, consistent with crushing of infill material about the fault tips. Prior to the second and third slips, no premonitory creep was observed. AE locations concentrate on a small patch within the fault plane. Source mechanisms are consistent with double couple events, orientated in agreement with the macro-scale fault plane geometry. For the natural fault, one stick slip event was induced, with a frictional coefficient of 0.72. Over 3000 AE were located. Again, the stick slip event can be located on the fault plane, in an area that had previously been acoustically quiet, presumably locked due to fault topography. Premonitory AE located mainly on the lower portion of the fault plane, and we did not observe an increase in AE rate immediately prior to rupture. Significant post-slip activity was located. b-values are constant at approximately 1.2 in the 100 seconds before slip. For the post-slip sequence there is an instant decrease (0.6) and subsequent recovery (1.0) in b-value. The surface topography generated considerable differences in premonitory, and post slip AE activity. However the ultrasonic signature of the slip events appears similar for both the saw-cut and natural fault. From an analysis of AE location error residuals, the initial nucleation size is estimated to be less than 3 mm in both experiments. However it is unclear whether we are resolving the size of the AE, or just its first particle motion; this depends on whether these AE can be modeled as dynamic or kinematic cracks (the latter refers to instantaneous motion of the whole source).

Young, R. P.; Thompson, B. D.; Lockner, D. A.

2005-12-01

307

Granular and semi-brittle descriptions of slip and creep  

NASA Astrophysics Data System (ADS)

Crustal deformation generates a wide range of creep and slip behaviors. Coseismic fault slip, aseismic creep, long-term strain transients, and slow-slip events all accommodate a great deal of tectonic strain and cause or contribute to destructive geohazards. Moreover, all have different time scales and exhibit differing degrees of periodicity. The dynamic frictional response of fault surfaces and fault rocks to slip may control a great deal of crustal slip and creep behaviors. Such is also the case for effective stress changes through fluid-pressure fluctuation and remote triggering. Yet, few existing friction and effective-stress models address the heterogeneity, range of metamorphic conditions, and range of deformational time scales that characterize natural shear zones. A useful framework for addressing this geological diversity is to treat natural shear zones as granular media. Physical experiments using analog materials provide some insight into such an approach. Shear zones of dry, granular materials produce stick-slip events via jamming phenomena, including influencing the periodicity and duration of events. When added to such granular mixtures, viscous materials enhance localization and smooth stick-slip events. Though such experimental approaches are difficult to simulate numerically, analytical and numerical solutions for fracture propagation into semi-brittle media can produce strain transients with a wide range of durations and recurrence intervals. A good example of how to use these concepts is in the characterization of possible slip behaviors for now-exhumed mid-crustal shear zones. Such shear zones tend to have deformed via predominantly viscous crystal plastic mechanisms, yet their creep behavior may well have produced strain transients including episodic tremor and slip. Fracture propagation into creeping media comprising mixtures of strong and weak materials could explain the generation of such phenomena. Geological observations of strong mafic lenses within weaker quartz-rich gneiss, cut by syntectonic quartz veins, are widely observed structural records of such behavior. Extending this analysis into the upper crust, however, will require a more complete framework for describing the strength of granular materials in the crust.

Hayman, N. W.; Lavier, L. L.

2013-12-01

308

Surface Slip During Large Owens Valley Fault Earthquakes  

NASA Astrophysics Data System (ADS)

Advances in our ability to image and analyze active faults using high-resolution lidar provide a unique opportunity to characterize the spatial distribution of slip during large earthquake surface ruptures. For strike-slip faults, along-strike compilation of laterally displaced geomorphic features measured using lidar enables the assessment of surface slip during historical and paleoearthquakes. Here, we seek to test whether surface slip during the 1872 Mw 7.4 - 7.9 Owens Valley earthquake, one of California's three largest historic ruptures, mimics the displacement during earlier events. We utilize recently developed analysis and processing tools to investigate EarthScope lidar data spanning the ~140-km-long Owens Valley surface rupture. We present over 70 new measurements of laterally displaced channels, terrace risers, meander scars, lake shorelines, and fan edges, with offsets up to 25 m. Where possible, we test the precision of lidar-based measurements by comparing our results to published field estimates of surface slip during this event. Displacements attributed to the most recent event (MRE) range between ~2 and 9 m, with an average horizontal offset of ~5 ± 2 m. Our along-strike compilation suggests that displacement gradients for the MRE are smooth at the >10 km length scale, in contrast with the distinctly peaked distribution estimated from previous field studies. Progressively larger offsets are attributed to earlier surface ruptures and may imply a similar amount of surface slip to the MRE (~5-7 m). Lateral slip during these events contributes to preliminary peaks in the cumulative offset frequency density at ~12 and ~18 m. The precision of these peaks likely reflects some bias toward well-preserved offsets, since the majority of offset features reflect displacement during the 1872 event. Taken together, our results indicate some variability in the amount of surface slip during Owens Valley surface ruptures, although large earthquakes appear to repeatedly rupture a similar fault extent. As we expand our database of offset measurements and further develop a long-term paleoseismic history, we will test whether or not similar patterns of surface slip are repeated as characteristic earthquakes during surface ruptures on the Owens Valley fault.

Haddon, E. K.; Amos, C. B.; Burgmann, R.

2012-12-01

309

How well do surface offsets represent earthquake slip at depth?  

NASA Astrophysics Data System (ADS)

Earthquake ruptures originate in the base of the unstable velocity-weakening part of the seismogenic layer and propagate into the velocity-strengthening upper stability region. Resulting deformation is transmitted to Earth's topography by driving slip along faults and block motions. Two factors affect this process: (1) the three-dimensional geometrical complexity and roughness of fault segments that control rupture continuity, and (2) spatiotemporal strength variations of the seismogenic layer that control the mechanical behavior of the fault zone. Earth's topography preserves evidence of past earthquakes as localized strain along fault scarps and fractures or distributed strain via off-fault folding and warping. These structures may be modified postseismically via afterslip and geomorphically degraded years to decades after rupturing. We investigate how well displaced geomorphic markers represent coseismic slip as it is transmitted from the seismogenic layer through to Earth's surface. We use lidar-derived measurements of single- and multi-event offset geomorphic markers to provide surface constraints on surface slip distributions of past earthquakes. Using FIMozFric, a numerical earthquake simulator that incorporates complex geomechanical properties of the seismogenic layer, we test various fault structural configurations and mechanical properties of the 2010 El Mayor-Cucupah earthquake. Initial simulations investigate the effect of simple fault complexities, such as stepovers and bends, on surface offsets using a simple two-layered seismogenic zone geometry. We then explore the effect of varying the mechanical complexity of the seismogenic zone by varying the relative geometries of the velocity-weakening and velocity-strengthening portions, thus simulating the variable mechanical properties of the upper lithosphere through which earthquakes propagate. Our results show that the geometrical complexity of faults controls the distribution of surface slip. More importantly, our simulations demonstrate that the mechanical configuration of the seismogenic layer within which faults are embedded affects how slip is distributed along single fault geometries and partitioned across zones with multiple fault strands. Variability in the depth of the velocity-weakening/velocity-strengthening interface appears to control the magnitude of single-event surface slip. These results shed light on the ability to confidently interpret paleoseismic and topographic records of the magnitude and recurrence of earthquakes, especially in relation to slip in a single earthquake. This is an especially important insight for efforts such as the Uniform California Earthquake Rupture Forecast (UCERF3) that aim to use lidar-derived slip in the most recent event as geologic constraints for expected slip magnitudes of future earthquakes but without accounting for the detailed lithology and structure of a fault zone.

Haddad, D. E.; Zielke, O.; Arrowsmith, R.

2013-12-01

310

Activities of olivine slip systems in the upper mantle  

NASA Astrophysics Data System (ADS)

We investigated the effect of pressure (P) on olivine [1 0 0](0 0 1) and [0 0 1](1 0 0) dislocation slip systems by carrying out deformation experiments in the Deformation-DIA apparatus (D-DIA) on single crystals of Mg2SiO4 forsterite (Fo100) and San Carlos (SC) olivine (Fo89), at P ranging from 5.7 to 9.7 GPa, temperature T = 1473 and 1673 K, differential stress ? in the range 140-1500 MPa, and in water-poor conditions. Specimens were deformed in axisymmetry compression along the so-called [1 0 1]c crystallographic direction, which promotes the dual slip of [1 0 0] dislocations in (0 0 1) plane and [0 0 1] dislocations in (1 0 0) plane. Constant ? and specimen strain rates (??) were monitored in situ by synchrotron X-ray diffraction and radiography, respectively. Comparison of the obtained high-P rheological data with room-P data, previously reported by Darot and Gueguen (1981) for Fo100 and Bai et al. (1991) for SC olivine, allowed quantifying the activation volume V* in classical creep power laws. We obtain V* = 9.1 ± 1.6 cm3/mol for Fo100. For SC olivine, we obtain V* = 10.7 ± 5.0 cm3/mol taking into account the oxygen-fugacity uncertainty during the high-P runs. These results, combined with previous reports, provide complete sets of parameters for quantifying the activities of olivine dislocation slip systems. Extrapolation of the rheological laws obtained for SC olivine crystals to conditions representative of natural deformations show that [1 0 0](0 1 0) slip largely dominates deformation in the shallow upper mantle. At depths greater than ˜65 km along a 20-Ma oceanic geotherm or ˜155 km along a continental geotherm, the dual activity of [1 0 0](0 0 1) and [0 0 1](1 0 0) slips becomes comparable to that of [1 0 0](0 1 0) slip. At depths greater than ˜240 km, [0 0 1](0 1 0) slip becomes dominant over all other investigated slip systems. Such changes in olivine dislocation-slips relative activity provide a straightforward explanation for the seismic anisotropy contrast and attenuation with depth observed in the Earth's upper mantle.

Raterron, Paul; Girard, Jennifer; Chen, Jiuhua

2012-06-01

311

Leg length discrepancy in patients with slipped capital femoral epiphysis  

PubMed Central

Background and purpose Leg-length discrepancy (LLD) can be a sequela of slipped capital femoral epiphysis (SCFE). We tried to identify factors that affect the development of LLD following SCFE. Patients and method We evaluated 85 patients who had been treated using percutaneous screw fixation. The average age of the patients at the time of surgery was 12 (8–16) years. The relationship of LLD and various clinical and radiographic parameters was evaluated: the degree of slip, articulotrochanteric distance (ATD), and articulotrochanteric distance difference (ATDD) (healthy side minus the side with SCFE). We assessed the relationship between ATDD and LLD based on scanogram. Results The average LLD was 1.4 (0.1–3.8) cm at 6 (2–15) years postoperatively. 48 of 85 patients had an LLD of greater than 1 cm and 10 patients had an LLD of greater than 2 cm. There was a correlation between the magnitude of LLD and the severity of the slip. There was no statistically significant correlation between LLD and the stability of the slip, age, BMI, sex, or race. There was a significant correlation between LLD and ATDD. Interpretation Patients with a high degree of slip are prone to develop clinically significant LLD. Although ATDD does not give the exact LLD, it can be used as a primary measurement, which should be supplemented with scanogram in cases of clinically significant differences in length.

2013-01-01

312

Insights from theory and experiments on slip flow in chromatography  

PubMed Central

Slip flow has become a topic of interest in reversed-phase liquid chromatography because it gives a flow enhancement that facilitates the use of submicrometer particles, providing a large improvement in separation efficiency. Moreover, slip flow provides an additional improvement in efficiency by reducing the velocity distribution in the mobile phase. The phenomenon of slip flow in open tubes is described in chromatographically relative terms. A recent paper in this journal is discussed, as it provides the first theoretical study of slip flow in packed beds, in this case for face-centered cubic geometry. The theory paper reveals that the presence of the packed bed introduces a heterogeneity in fluid velocities that is absent in open tubes, reducing the additional improvement in efficiency from slip flow. The recent paper also suggests that there is yet another factor improving efficiency, which is size-exclusion of proteins from regions of stagnant flow. The latter is supported by recently published data on restricted protein diffusion in face-centered cubic silica colloidal crystals. Extremely low plate heights are enabled by use of submicrometer particles, and further improvement appears to be possible when the analyte size is on the order of 1% of the particle diameter or larger.

Wu, Zhen; Rogers, Benjamin J.; Wei, Bingchuan; Wirth, Mary J.

2014-01-01

313

Stokes flow in a pipe with distributed regions of slip  

NASA Astrophysics Data System (ADS)

Steady pressure-driven Stokes flow in a circular pipe is investigated analytically in the case where the pipe surface contains periodically distributed transverse regions of zero surface shear stress. One physical motivation for this problem is the recent experimental observation of nanobubbles on smooth hydrophobic surfaces (Ishida et al. (2000) Langmuir vol. 16, Tyrrell and Attard (2001) Phys. Rev. Lett. vol. 87) while a second motivation is the possible presence of bubbles trapped on rough surfaces. The bubbles may provide a zero shear stress boundary condition for the flow and modify considerably the friction generated by the solid boundary. In the spirit of experimental studies probing apparent slip at solid surfaces, the effective slip length of the resulting macroscopic flow is evaluated numerically and asymptotically as a function of the relative width of the no-slip and no-shear stress regions and their distribution along the pipe. Comparison of the model with experimental studies of pressure-driven flow in capillaries and microchannels is made and a possible interpretation of the results is offered which is consistent with a large number of nano-size and micron-size bubbles coating the solid surface. Finally, an explanation for the seemingly paradoxical behavior of the measured slip length increasing with system size reported by Watanabe et al. (1999) (J. Fluid Mech. vol. 381) is proposed and the possibility of a shear-dependent effective slip length is suggested.

Lauga, Eric; Stone, Howard A.

2002-11-01

314

Stick-slip nanofriction in trapped cold ion chains  

NASA Astrophysics Data System (ADS)

Stick slip—the sequence of mechanical instabilities through which a slider advances on a solid substrate—is pervasive throughout sliding friction, from nanoscales to geological scales. Here we suggest that trapped cold ions in an optical lattice can also be of help in understanding stick-slip friction, and also the way friction changes when one of the sliders undergoes structural transitions. For that scope, we simulated the dynamical properties of a 101-ion chain, driven to slide back and forth by a slowly oscillating electric field in an incommensurate periodic “corrugation” potential of increasing magnitude U0. We found the chain sliding to switch, as U0 increases and before the Aubry transition, from a smooth-sliding regime with low dissipation to a stick-slip regime with high dissipation. In the stick-slip regime the onset of overall sliding is preceded by precursor events consisting of partial slips of a few ions only, leading to partial depinning of the chain, a nutshell remnant of precursor events at the onset of motion also observed in macroscopic sliders. Seeking to identify the possible effects on friction of a structural transition, we reduced the trapping potential aspect ratio until the ion chain shape turned from linear to zigzag. Dynamic friction was found to rise at the transition, reflecting the opening of other dissipation channels.

Mandelli, D.; Vanossi, A.; Tosatti, E.

2013-05-01

315

Scaling analysis for the investigation of slip mechanisms in nanofluids.  

PubMed

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

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

2011-01-01

316

Scaling analysis for the investigation of slip mechanisms in nanofluids  

PubMed Central

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.

2011-01-01

317

Path Following with Slip Compensation for a Mars Rover  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

318

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

DOEpatents

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).

Cleveland, Joe R. (West Hills, CA)

1997-01-01

319

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

DOEpatents

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.

Cleveland, J.R.

1997-03-18

320

Correlation between stick-slip frictional sliding and charge transfer  

NASA Astrophysics Data System (ADS)

A decade ago, Budakian and Putterman [Phys. Rev. Lett. 85, 1000 (2000)]10.1103/PhysRevLett.85.1000 ascribed friction to the formation of bonds arising from contact charging when a gold tip of a surface force apparatus was dragged on polymethylmethacrylate surface. We propose a stick-slip model that captures the observed correlation between stick-slip events and charge transfer, and the lack of dependence of the scale factor connecting the force jumps and charge transfer on normal load. Here, stick-slip dynamics arises as a competition between the viscoelastic and plastic deformation time scales and that due to the pull speed with contact charging playing a minor role. Our model provides an alternate basis for explaining most experimental results without ascribing friction to contact charging.

Ananthakrishna, G.; Kumar, Jagadish

2010-08-01

321

Superplastic flow lubricates carbonate faults during earthquake slip  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

322

Stacking fault energies and slip in nanocrystalline metals.  

PubMed

The search for deformation mechanisms in nanocrystalline metals has profited from the use of molecular dynamics calculations. These simulations have revealed two possible mechanisms; grain boundary accommodation, and intragranular slip involving dislocation emission and absorption at grain boundaries. But the precise nature of the slip mechanism is the subject of considerable debate, and the limitations of the simulation technique need to be taken into consideration. Here we show, using molecular dynamics simulations, that the nature of slip in nanocrystalline metals cannot be described in terms of the absolute value of the stacking fault energy-a correct interpretation requires the generalized stacking fault energy curve, involving both stable and unstable stacking fault energies. The molecular dynamics technique does not at present allow for the determination of rate-limiting processes, so the use of our calculations in the interpretation of experiments has to be undertaken with care. PMID:15156199

Van Swygenhoven, H; Derlet, P M; Frøseth, A G

2004-06-01

323

Dynamic mechanisms for apparent slip on hydrophobic surfaces  

NASA Astrophysics Data System (ADS)

Recent experiments [Y. Zhu and S. Granick, Phys. Rev. Lett. 87, 096105 (2001)] have measured a large, shear-dependent fluid slip at partially wetting fluid-solid surfaces. We present a simple model for such a slip, motivated by the recent observations of nanobubbles on hydrophobic surfaces. The model considers the dynamic response of bubbles to change in hydrodynamic pressure, due to the oscillation of a solid surface. Both the compression and diffusion of gas in the bubbles decrease the force on the oscillating surface by a “leaking mattress” effect, thereby creating an apparent shear-dependent slip. With bubbles similar to those observed by recent atomic force microscopy, the model predicts a force decrease consistent with the experimental measurements of Zhu and Granick.

Lauga, Eric; Brenner, Michael P.

2004-08-01

324

Active rigidity joint  

NASA Astrophysics Data System (ADS)

Unimorph active rigidity joints, constructed from Shape Memory Alloy and Shape Memory Polymer and capable of bending actuation, are reported in this work. An embedded aluminum shim was added to each joint as a structural element to facilitate actuation. Joints were actuated using ohmic Tri-Phase and pulse heating processes with different results. It appeared that openloop position control could be achieved using pulse heating. Actuator improvements and future experiments are proposed.

Geeng, Franklin; Manzo, Justin; Garcia, Ephrahim

2010-03-01

325

Reduced Aftershock Productivity in Regions with Known Slow Slip Events  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

326

Along Strike Variations in Episodic Tremor and Slip Rate  

NASA Astrophysics Data System (ADS)

The geodetic signal due to Episodic Tremor and Slip (ETS) along strike of the Cascadia Subduction Zone (CSZ) is much larger in Washington north of ~46°N than in Oregon from 2004 to 2011. Similarly, ETS recurrence in Cascadia increases from two years in Oregon to ~14 months near Puget Sound, Washington. Among the four seismically and geodetically detected ETS events that ruptured northern to central Oregon (June 2011, August 2009, July 2007 and November 2005), only the 2009 event ruptured from southern Puget Sound to central Oregon, crossing ~46°N. Seismically observed tremor and geodetic displacements are used to inspect the August 2009 ETS event. Elastic half-space models indicate interface slip north of 45.6+0.3/-0.5°N is large (64 mm at 112° CCW from north) and reduces by ~52% (31 mm at 119° CCW from north) to the south. The moment magnitude is 6.8. We seek to understand why there is more apparent slip in Washington than in Oregon for the 2009 event as well as for the average GPS displacement per year (sum of vector displacements of each ETS event since 2004 divided by GPS site duration of operation). We use an elastic half space model with GPS time series from the Pacific Northwest Geodetic Network (PANGA) and the Plate Boundary Observatory (PBO) to invert for the slow slip rate and explore key model parameters such as the width of the slipping zone, fault dip and depth to try to explain the apparent difference in average GPS displacement per year caused by ETS events. If the slip deficit observed in Oregon is real, then how will it eventually be accommodated?

Schmalzle, G. M.; Creager, K. C.; Delbridge, B. G.; Wech, A.; Khazaradze, G.

2012-12-01

327

A series of transient slip events on Kilauea volcano, Hawaii.  

NASA Astrophysics Data System (ADS)

Deformation on Kilauea volcano, Hawaii is monitored by a network of continuously recording GPS stations, among other methds. Since its installation in 1996, the GPS network has detected four spatially coherent accelerations on Kilauea's south flank that are not caused by either intrusions or earthquakes. These events, each lasting several hours to two days, occurred in September 1998, November 2000, July 2003, and January 2005. Previously, Cervelli et al., (Nature, 2002) interpreted the 2000 event as a silent earthquake due to slip on a sub-horizontal fault beneath Kilauea's south flank. We inverted the cumulative displacements ( less than 2 cm) using a simulated annealing algorithm for each event and found similarly sized, near horizontal, uniform slip source locations for all four events at depths of ~6 km. The estimated slip magnitudes are between 9 and 15 cm, with the upper block moving seaward. The 2005 event is the largest detected to date. Volcano-tectonic (VT) earthquakes on the south flank of Kilauea are typically restricted to the volume between the East Rift Zone and the Hilina and Poliokeawe Palis. Seismicity in this volume increased significantly during the silent events at depths of 5-10 km. However, all of the VT earthquakes were small ( less than M3) and their cumulative moment does not account for the moment released during the silent slip events. We are currently examining seismic waveform data for evidence of other signals, such as non-volcanic tremor, that might be associated with the slip events. To determine the exact onset and duration of the silent earthquakes, we invert for slip as a function of time directly from raw GPS phase and pseudorange observations. The November 2000 silent earthquake was preceded 9 days earlier by nearly 1 m of rainfall, which was speculated in Cervelli et al., (Nature, 2002) to have reduced fault stability through surface loading or pore pressure increase. In contrast, both the 2003 and 2005 events occurred without anomalous rainfall.

Desmarais, E. K.; Segall, P.; Miklius, A.; Cervelli, P.

2005-12-01

328

Characterization of friction joints subjected to high levels of random vibration  

NASA Astrophysics Data System (ADS)

When designing optical devices, the alignment of every element is integral to the proper functionality of the device. If any of these elements is secured by means of a friction joint, it is important to understand the limitations of the joint when vibrations (mainly during launch) occur; a phenomenon called "stick-slip" may happen and permanently displace joints relying on friction and cause optical misalignments. There is little to no data documenting the characteristics of the "stick-slip" phenomenon on friction joints under random vibratory motion. The test program was designed with the aim of gathering data that would broaden the understanding of the "stick-slip" phenomenon and among other things provide sufficient information to quantify the static coefficients of friction of several single-bolt friction joint material pairings. This paper describes the test program in detail including test sample description, test procedures, and vibration test results of multiple test samples. The material pairs used in the experiment were Aluminum-Aluminum, Aluminum- Dicronite coated Aluminum, and Aluminum-Plasmadize coated Aluminum. Levels of vibration for each set of twelve samples of each material pairing were gradually increased until all samples experienced substantial displacement. Data was collected on 1) acceleration in all three axes, 2) relative static displacement between vibration runs utilizing photogrammetry techniques, and 3) surface galling and contaminant generation. This data was used to estimate the values of static friction during random vibratory motion when "stick-slip" occurs and compare these to static friction coefficients measured before and after vibration testing.

de Santos, Omar; MacNeal, Paul

2012-03-01

329

Coulombic wall slip of concentrated soft-particle suspensions  

NASA Astrophysics Data System (ADS)

The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.

Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter

2013-06-01

330

Fault Slip Embedded in Creep: Insight into Tectonic Tremors and Slow Slip Events from Acoustic and Optical Monitoring of Fractures  

NASA Astrophysics Data System (ADS)

Observations of temporal and spatial correlations between slow slip earthquakes and tectonic tremor activity suggest a physical relation between them. Early descriptions of mechanisms relating these phenomena simply attributed the relation between seismic and aseismic events to fluid mediated processes. More recent hypotheses suggest that tectonic tremors are bursts of seismic energy due to the rupturing of small asperities within slow slipping regions. Here we present laboratory results of a unique experimental setting aimed at understanding the response to transient loads of a system of small asperities embedded in creep as a model of tectonic tremor activity triggered by slow slip and modulated by tides. We performed mode I crack propagation experiments on glass bead blasted and annealed 2D interfaces of transparent material (Polymethylmethacrylate) where fracture fronts were confined to the 2D weakness plane of the heterogeneous interface. We monitored acoustic emissions (AE) with piezo-electric sensors surrounding the crack front line. We also optically monitored the rupture front line with up to 1000 frames per second. The experimental loading conditions produce quasi-static front propagation at slow average speeds. Image processing reveals de-pinning along the front that we characterize as intermittent opening during slow front propagation. AE locations strongly correlate to the spatiotemporal clustering of the de-penning events along the front. Moreover, this correlation is preserved at the time of imposed transient fluctuations in loading during front propagation. Using the analogy between mode I and modes II and III fractures, our results translate into intermittent slip on faults linked to clustering of seismic activity produced by the breakage of asperities embedded in creeping regions with no need of invoking fluid mediated processes. Thus our experiments help reveal the interplay between aseismic and seismic slip on faults. We also observe qualitative similarities between the growth and migration of the embedded slip events in our experiments and migration patterns of tectonic tremors.

Elkhoury, J. E.; Lengline, O.; Ampuero, J. P.; Schmittbuhl, J.

2010-12-01

331

Kinematically Coupled Strike-Slip and Normal Faults in the Lake Mead Strike-Slip Fault System, Southeast Nevada  

NASA Astrophysics Data System (ADS)

The Lake Mead fault system consists of a ~95 km long, northeast-trending zone of strike-slip faults of Miocene age that accommodate a total left-lateral offset of 20-65 km. We use a combination of detailed field mapping and numerical modeling to show that a previously unnamed left-lateral strike-slip segment of the Lake Mead fault system and a dense cluster of dominantly west-dipping normal faults acted in concert to accommodate regional left-lateral offset. We suggest that the strike-slip fault that we refer to as the Pinto Ridge fault: (1) was kinematically related to other faults of the Lake Mead fault system; (2) was responsible for the creation of the normal fault cluster at Pinto Ridge; and (3) utilized these normal faults as linking structures between separate strike-slip fault segments to create a longer, through-going fault. Results from numerical models demonstrate that the observed location and curving strike patterns of the normal fault cluster is consistent with the faults having formed as secondary structures as the result of the perturbed stress field around the slipping Pinto Ridge fault. Comparison of mechanical efficiency of various normal fault geometries within extending terranes suggests that the observed west dip of normal faults reflects a west- dipping anisotropy at depth, such as a detachment. The apparent terminations of numerous strike-slip faults of the Lake Mead fault system into west-dipping normal faults suggest that a west-dipping detachment may be regionally coherent.

Kattenhorn, S. A.; Marshall, S. T.; Cooke, M. L.

2008-12-01

332

Tape Joint Stiffness.  

National Technical Information Service (NTIS)

This redport evaluates the stiffness for a standard tape-joint structural connection. This stiffness is frequently necessary when modeling a structure (e.g., a shock model). In general, for a standard cylindrical tape joint, the stiffness is 1.2 times gre...

R. P. Rechard

1986-01-01

333

Behavior of jointed pipelines  

Microsoft Academic Search

Experimental data on the axial, bending and torsional behavior of ductile cast iron pipes with rubber gasket joints is presented. Analytical expressions are provided which predict the resistance mechanisms and behavior of the joints. The bending mechanism is found to be quite different from the axial and torsional mechanism. By repeating the tests in a specially designed soil box, the

Singhal

1984-01-01

334

Investigation of joint disease  

Microsoft Academic Search

The role of nuclear medicine in the diagnosis and management of the major arthropathies is critically reviewed, with particular reference to osteoarthritis, rheumatoid and similar forms of arthritis, ankylosing spondylitis, non-specific back pain, gout, the neuropathic joint, avascular necrosis, infection and the consequences of prosthetic joint insertion. Attention is drawn both to practical applications and deficiencies in current techniques and

M. V. Merrick

1992-01-01

335

Bone and joint infections  

Microsoft Academic Search

Infections involving bone and joint are a significant cause of morbidity and mortality. They can result in prolonged hospital stays, long courses of systemic antibiotics and frequently will require surgical intervention. In this review we will cover the commonest infections seen clinically. We have also chosen to divide the review into two sections; infections involving native tissue\\/joints and infections relating

Tom Darton; Robert Townsend

2010-01-01

336

Campylobacter prosthetic joint infection.  

PubMed

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

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

2014-05-01

337

Prosthetic Elbow Joint.  

National Technical Information Service (NTIS)

An artificial manually positionable elbow joint for use in an upper extremity, above-elbow, prosthetic which provides a locking feature that is easily controlled by the wearer is described. The instant elbow joint is very strong and durable to withstand t...

B. Weddendorf

1992-01-01

338

Joint warfare system (JWARS)  

Microsoft Academic Search

The Joint Warfare System (JWARS) is a campaign-level model of military operations that is currently being developed under contract by the Office of the Secretary of Defense (OSD) for use by OSD, the Joint Staff, the Services, and the War fighting Commands. The behavior of military forces can be simulated from ports of embarkation through to their activities in combat.

A. Simlote

2003-01-01

339

General joint laxity  

Microsoft Academic Search

General joint laxity is measured with the hyperextensometer, and by analyzing the values obtained in a group of European subjects norm curves are drawn up related to age and sex. The values found in various orthopedic diseases are put into these curves, and the importance of general joint laxity is discussed.

L. Dubs; N. Gschwend

1988-01-01

340

Joint Seal Materials.  

National Technical Information Service (NTIS)

Three major experimental field installations of approximately 7 types of joint sealing materials were used to compare and evaluate the products of numerous sealant manufacturers. The sealants were placed in contraction joints (3/8 in. x 2 in.) which were ...

J. G. F. Hiss J. R. Lambert W. M. McCarty

1968-01-01

341

Pressure slip casting of bimodal silicon carbide powder suspensions  

Microsoft Academic Search

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

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

1999-01-01

342

Dynamic action units slip in speech production errors  

Microsoft Academic Search

In the past, the nature of the compositional units proposed for spoken language has largely diverged from the types of control units pursued in the domains of other skilled motor tasks. A classic source of evidence as to the units structuring speech has been patterns observed in speech errors – “slips of the tongue”. The present study reports, for the

Louis Goldstein; Marianne Pouplier; Larissa Chen; Elliot Saltzman; Dani Byrd

2007-01-01

343

Harmonic analysis of slip energy recovery induction motor drives  

Microsoft Academic Search

The impact of electric drives on the power system in terms of harmonic generation is becoming increasingly important. Slip energy recovery induction motor drives (SERIMDs) have the rectifier and inverter connected to the rotor instead of the stator (the case in most conventional drives). The harmonic content of the SERIMD is thus quite different and arguably, less onerous than conventional

L. Refoufi; P. Pillay

1994-01-01

344

Commutation angle analysis of the slip energy recovery drive  

Microsoft Academic Search

A well known characteristic of the slip energy recovery drive (SERD) is the large commutation overlap of the rotor side rectifier, which compromises the accuracy of simplified dq models often used for its simulation. In this paper the variation of the rectifier commutation angle and the factors that determine its magnitude are investigated using a detailed hybrid abc-dq model of

S. A. Papathanassiou; M. P. Papadopoulos

1998-01-01

345

Modeling and performance of slip energy recovery induction motor drives  

Microsoft Academic Search

This program can be used to examine the transient performance of slip energy recovery drives for the proper rating of semiconductor devices or to examine the effects of faults on the associated power system on the drive performance. Current and speed controllers designed using linear techniques can be evaluated using this program as well. A computer using a fourth-order Runga-Kutta

E. Akpinar; P. Pillary

1990-01-01

346

Slip, Swim, Mix, Pack: Fluid Mechanics at the Micron Scale  

Microsoft Academic Search

This talk summarizes my thesis work which was advised by Michael P. Brenner and Howard A. Stone at Harvard University and is devoted to fluid behavior at the micrometer length scale. We consider four different problems. We first address the topic of the no-slip boundary condition in Newtonian liquids. After briefly reviewing the field, we (1) present models for apparent

Eric Lauga

2006-01-01

347

Influence of Slip on the Flow Past Superhydrophobic Circular Cylinders  

Microsoft Academic Search

Superhydrophobic surfaces have been shown to produce significant drag reduction for both laminar and turbulent flows of water through large and small-scale channels. In this presentation a series of experiments will be presented which investigate the effect of superhydrophobic-induced slip on the flow past a circular cylinder. In these experiments, circular cylinders are coated with a series of superhydrophobic surfaces

Jonathan Rothstein; Robert Daniello; Nangelie Ferrer; Pranesh Muralidhar

2010-01-01

348

A generating mechanism for apparent fluid slip in hydrophobic microchannels  

Microsoft Academic Search

Fluid slip has been observed experimentally in micro- and nanoscale flow devices by several investigators [e.g., Tretheway and Meinhart, Phys. Fluids 14, L9 (2002); Zhu and Granik, Phys. Rev. Lett. 87, 096105 (2001); Pit et al., Phys. Rev. Lett. 85, 980 (2000); and Choi et al., Phys. Fluids 15, 2897 (2003)]. This paper examines a possible mechanism for the measured

Derek C. Tretheway; Carl D. Meinhart

2004-01-01

349

Hypoid Gear Lubricants for Slip-Lock Differentials.  

National Technical Information Service (NTIS)

Primary alkyl amines of 12 to 24 carbon atoms are used as additives to gear lubricants. From 0.2 to 1.0 percent by weight of primary C12 to C24 alkyl amine is added to a gear lubricant to eliminate or reduce the noise or chatter in a limited slip differen...

R. O'Halloran

1965-01-01

350

Micro-Vibration-Based Slip Detection in Tactile Force Sensors  

PubMed Central

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.

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

2014-01-01

351

Slip modelling and aided inertial navigation of an LHD  

Microsoft Academic Search

This paper describes the theoretical development and experimental evaluation of a guidance system for an autonomous load, haul and dump truck (LHD) for use in underground mining. The particular contributions of this paper are in designing the navigation system to be able to cope with vehicle slip in rough uneven terrain using information from an inertial navigation system (INS) and

S. Scheding; G. Dissanayake; E. Nebot; H. Durrant-Whyte

1997-01-01

352

Slip-Free Driving Method for Nonresonant Piezoelectric Actuator  

NASA Astrophysics Data System (ADS)

It is generally considered that in the ultrasonic motor the motion always slips and scratches. The nonresonant ultrasonic motor (NRUSM) expected for future precision stage systems should, however, overcome the difficulties of the wear of friction materials, which has been encountered in the use of conventional ultrasonic motors. The wear occurs by slipping and may be reduced by material selection. In this paper, we focus on the control method at actuation to prevent slipping. The advantages of NRUSM in the ability to control the drive frequency as well as the drive amplitude are shown, and this is effective in reducing wear and obtaining long-term stability. The drive frequency condition for no slippage under sinusoidal waveforms was calculated. The experimental results correspond to the theoretical calculated drive frequency. Because the resultant values of the frequencies are low for practical applications, we present the slip-free actuation method of using the new actuator’s driving waveform and time chart in order to drive the stage at constant accelerated motion.

Endo, Taishi; Egashira, Yoshiya; Furukawa, Hiroyuki; Hashiguchi, Hiroyuki; Kosaka, Kouji; Watanabe, Masayuki; Miyata, Noboru; Moriyama, Shirou; Sasaki, Syunichi; Nakada, Akira; Ohmi, Tadahiro; Kubota, Hiroshi

2005-07-01

353

Deformation of overburden soil induced by thrust fault slip  

Microsoft Academic Search

When the blind thrust fault slips due to earthquakes, overburden soil strata may deform and fail leading to a development of a coseismic fault zone. How overburden soil strata will deform or be faulted is an essential issue in the evaluation on the safety of ground\\/underground infrastructures located near the potential plastic zone. On the basis of previous work by

Ming-Lang Lin; Chun-Fu Chung; Fu-Shu Jeng

2006-01-01

354

Slip observer for walking on a low friction floor  

Microsoft Academic Search

This paper presents a slip observer towards stabilizing biped walks on a low friction floor. Although biped humanoid robots are expected to easily adapt to environments designed for human, in fact they tend to tip over easily on real environments. For a practical use, it is one of important issues to stabilize a biped walking on an unexpected slippery floor

Kenji Kaneko; Fumio Kanehiro; Shuuji Kajita; Mitsuharu Morisawa; Kiyoshi Fujiwara; Kensuke Harada; H. Hirukawa

2005-01-01

355

Transient Analysis of Slip Flow and Heat Transfer in Microchannels  

Microsoft Academic Search

Hybrid analytical-numerical solutions for transient flow and transient convective heat transfer within microchannels are presented. Analytical solutions for flow transients in microchannels are obtained by making use of the integral transform approach. The proposed model involves the transient fully developed flow equation for laminar regime and incompressible flow with slip at the walls in simple channel geometries. The solution is

F. V. Castellões; C. R. Cardoso; P. Couto; R. M. Cotta

2007-01-01

356

Flash weakening of serpentinite at near-seismic slip rates  

NASA Astrophysics Data System (ADS)

To investigate the processes responsible for dynamic frictional weakening in antigorite serpentinite, we conducted single-velocity and velocity-stepping friction experiments at slip rates (V) from 0.01 to 0.4 m s-1, sliding displacements up to 40 mm, and a normal stress of 5 MPa. Single-velocity experiments demonstrate an approximately 1/V dependence of friction on velocity above a characteristic weakening velocity Vw ? 0.1 m s-1, consistent with theoretical predictions for flash heating and subsequent weakening of asperities. Velocity-stepping experiments impose stepwise increases in slip rate show stepwise weakening at slip rates above Vw. Scanning electron microscopy of experimental fault surfaces reveals nanoparticle gouge textures at raised sites (˜10 ?m in diameter) in tests that exhibit dramatic weakening. Furthermore, X-ray diffraction analyses of fault gouge from the sliding surface document the formation of significant talc in these tests, indicating that weakening temperatures reached 500°C-700°C. In contrast, no talc is observed in samples for which V remained significantly below Vw. The observed value for Vw is consistent with published microphysical models for flash weakening when independent constraints on the thermal stability and contact strength of antigorite are considered. Finally, while serpentinite displays velocity-strengthening behavior at plate tectonic slip rates, our results indicate that seismic ruptures propagating into serpentinized regions in the shallow lithosphere may trigger seismicity or slow earthquakes, after limited amounts of displacement.

Kohli, Arjun H.; Goldsby, David L.; Hirth, Greg; Tullis, Terry

2011-03-01

357

Slip Diffusion and Lévy Flights of an Adsorbed Gold Nanocluster  

Microsoft Academic Search

Anomalous diffusion of a gold nanocrystal Au140, adsorbed on the basal plane of graphite, exhibiting Lévy-type power-law flight-length and sticking-time distributions, is predicted through extensive molecular dynamics simulations. An atomistic collective slip-diffusion mechanism is proposed and analyzed.

W. D. Luedtke; Uzi Landman

1999-01-01

358

Slip History of Global Major Deep-focus earthquakes  

NASA Astrophysics Data System (ADS)

The physical mechanisms of deep-focus earthquakes puzzle scientists, since the large confining stress would make the deformation ductile than brittle failure. Several hypotheses have been proposed to explain the deep earthquakes, including dehydration embrittlement, transformational faulting and shear thermal instability. In this presentation, we apply a finite fault inversion algorithm to systematically study the slip histories of global deep-focus earthquakes with Mw > 7.0 and depth > 410 km. The finite fault inversion algorithm is based on waveform inversions of body waves in the wavelet domain, and inverts the fault slip, rake angle, rupture initiation time, and slip rate function using a simulated annealing approach. A total of 27 events are investigated, and 19 of them can be reasonably fit by the finite fault inversion. 15 of the 19 events prefer the low-angle fault planes, 2 prefer the high-angle planes, and 2 show ambiguity. A significant number of events have multiple rupture planes, which are spatially and temporally separated and have different slip directions. The poor fitting of the rest 8 events by the finite-fault inversion is perhaps due to existence of focal mechanisms different from those prescribed by the finite fault inversion program. We will discuss how different proposed mechanisms of deep earthquakes explain the seismic results.

Chen, Y.; Wen, L.; Ji, C.

2012-12-01

359

Vehicle velocity, side slip angles and yaw rate estimation  

Microsoft Academic Search

This paper presents a nonlinear body side slip angle and yaw rate observer based on an estimation of the vehicle velocity. The design of this observer uses a linearisa- tion which is modelled on the Luenberger observer and the output used for this observer is the lateral acceleration. The rotational equivalent wheel speeds are used to estimate the vehicle velocity.

H. Cherouat; M. Braci; S. Diop

2005-01-01

360

An Analysis of Strain Accumulation on a Strike Slip Fault  

Microsoft Academic Search

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

D. L. Turcotte; D. A. Spence

1974-01-01

361

Research on traction slip control algorithm for parallel hybrid cars  

Microsoft Academic Search

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

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

2011-01-01

362

Calculating longitudinal wheel slip and tire parameters using GPS velocity  

Microsoft Academic Search

While tire parameters are quite important to both current vehicle control systems and proposed future systems, these parameters are subject to considerable variability and are difficult to estimate while driving due to the unavailability of absolute vehicle velocity. This paper details a method of generating longitudinal tire force-slip curves using absolute velocity information from the Global Positioning System (GPS). By

Shannon L. Miller; Brett Youngberg; Alex Millie; Patrick Schweizer; J. Christian Gerdes

2001-01-01

363

Two-plane balance and slip-ring design  

NASA Technical Reports Server (NTRS)

A 3.25 cm (1.28 in.) two plane balance and eight channel slip ring assembly has been designed to measure and transmit the thrust (667-N;150-lb) and torque (135-N-m;100-lb-ft) components produced by wind tunnel model turboprops and drive motors operating at 300 Hz.

Luna, P. M.

1985-01-01

364

Fluid slip ring transfers coolant to rotating equipment  

NASA Technical Reports Server (NTRS)

Rotating fluid coupler, consisting of rotor and housing made of aluminum, that is concentric with electrical slip-ring assembly, transfers cooling fluid to instrumentation undergoing environmental tests on rotating platform. Rotating fluid coupler permits unlimited platform revolutions and eliminates danger of lines being pulled loose from supplies.

Mains, D. K.

1971-01-01

365

Superconducting cable joint resistance  

SciTech Connect

This paper reports on results of a parametric study of the 4.2 K resistance of lap joints between two 27-strand cables of multifilamentary Nb{sub 3}Sn wire. All joints were between ribbon terminations made rolling copper-encapsulated cable ends flat. Resistances as functions of current were inferred from current decay time constants of cable-in-conduit conductor loops connected by the joints. The resistances of twenty three samples were measured (range of 0.2 to 3 n{Omega}). It was found that lap joint resistance was a function of current. The influences of solder versus no solder, solder thickness, indium versus tin-lead, ribbon surface oxidation, solder flux, cable twist pitch, wire chrome plating, clamping pressure during heat treatment, ribbon aspect ratio, and joint length are reported.

Herbelot, O.; Steeves, M.M.; Hoening, M.O. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)

1991-03-01

366

Steady-state friction during earthquake slip: Fact or myth?  

NASA Astrophysics Data System (ADS)

The rupture front of an earthquake propagates along a fault while activating countless patches. Each patch undergoes intense deformation variations from rest before the front developing to acceleration, weakening, deceleration and healing. While it is unlikely that steady-state stage would materialize in such history during rise-time, the modeling of earthquake rupture is almost exclusively based on friction measurements conducted under steady-state condition. An alternative approach is presented here. Experimentally, the friction strength of a fault is determined by its relations to the slip-distance and slip-velocity, and these relations are implicitly assumed to be rock properties. Recent observations however, show that these relations strongly depend on the slip-velocity history. Consider three styles of velocity loading: Impact (abrupt increase followed by gradual deceleration), constant (steady velocity), and ramp (gradual increase followed by abrupt deceleration). Chang et al. (2012) found that running the same sample (Sierra White granite) under different velocity loading yielded different relations: Impact loading had much shorter critical weakening distance (0.03 m for impact and 1-3 m for constant), and drastic dynamic weakening under high velocity (V > 0.1 m/s), whereas dynamic strengthening was observed under V > 0.05 m/s for constant velocity. Similar behavior was recently observed for an experimental fault made of syenite under impact and ramp loading. Further, under impact velocity, the period of velocity increase (acceleration) overlaps the period of fault weakening. This correlation is not unique and similar weakening-acceleration associations were reported in stick-slip experiments (Ohnaka & Yamashita, 1989), rotary shear (Goldsby & Tullis, 2011), and Kolsky impact shear experiments (Yuan & Prakash, 2008). These studies greatly differ from each other in slip distance, normal stress, acceleration, and slip-velocities with the outstanding commonality of impact velocity loading. Analyses of seismic data (e.g., Tinti et al., 2005) and numerical simulation of earthquake rupture (e.g., Day et al., 2005), indicate that the early slip of a fault patch is characterized by intense acceleration. Based on these experimental and modeling results we conclude that dynamic frictional strength, which is determined in steady-state experiments, is not necessarily relevant to fault strength during earthquakes. More relevant experiments should be conducted under impact loading that better fits high velocity rupture propagation.

Reches, Zeev; Chang, Jefferson

2013-04-01

367

Do All Large Strike-slip Earthquakes Have Supershear Ruptures?  

NASA Astrophysics Data System (ADS)

Studying the rupture speeds of earthquakes is of broad interesting for earthquake research because it has a large effect on the strong near-field shaking that causes damage during earthquakes. Also rupture speed is a key observation for understanding the controlling stresses and friction during an earthquake, yet the speed and its variations are usually difficult to determine. Using only far-field seismic waveforms, which is the only data available for many large earthquakes, there are problems for estimating the rupture speed with standard waveform inversions, due to trade-off between the rupture speed and the slip location. Here we applied a back projection method to estimate the rupture speeds of Mw ? 7.5 strike-slip earthquakes since 2001 which could be analyzed using Hi-net in Japan. We found that all events had very fast average rupture speeds of 3.0-6.0 km/s, which are near or greater than the local shear wave velocity (supershear). These values are faster than for thrust and normal faulting earthquakes that generally rupture with speeds of 1.0-3.0 km/s. Considering the depth-dependent shear-wave velocity, the average propagation speeds for all of the strike-slip events are closer to or greater than the shear wave velocity (Figure 1). For large strike-slip events, transition from subshear to supershear usually occurs within distances of 15 to 30 km from the initiation, which is probably the reason for the scarcity of observed supershear earthquakes for smaller magnitudes. Earthquakes with supershear ruptures can cause more damage than events with subshear ruptures because of the concentration of energy in the forward direction of the rupture. Numerical modeling shows strong focusing and other effects of energy at the rupture front which can intensify the ground motions. A recent example is the April 13, 2010 Qinghai, China earthquake (Mw 6.9), where a moderate-size event caused extensive damage in the Yushu region at the southeastern end of the fault. Careful evaluation of long and straight strike-slip faults should be emphasized for predicting strong ground motions due to supershear rupture. a: Average rupture speeds for Mw ? 7.5 strike-slip earthquakes. For comparison, dip-slip earthquakes are also shown. The blue dashed line presents the S wave velocity model of PREM for comparison. b: Rupture velocities are shown as ratio to the local S wave velocity, as a function of depth.

Wang, D.; Mori, J. J.; Koketsu, K.

2013-12-01

368

Flash Heating of Crustal Rocks at Seismic Slip Rates  

NASA Astrophysics Data System (ADS)

Recent experiments have demonstrated that rocks undergo extreme frictional weakening at near-earthquake slip rates due to the thermal degradation of the strength, or even melting, of microscopic asperity contacts on their sliding surfaces (Goldsby and Tullis, 2012). These previous experiments, conducted at constant normal stress and slip rates of up to ~0.4 m/s, revealed a 1/V dependence of friction on slip rate above a characteristic weakening velocity, Vw, in accord with theories of flash heating (e.g., Rice, 2006). The weakening velocity obtains values of ~0.1 m/s for many crustal silicate rocks (Goldsby and Tullis, 2012). Here we test two further predictions of flash-heating theory - that the degree of weakening saturates at slip rates approaching 1 m/s, and that the weakening behavior due to flash heating is independent of normal stress - by testing samples at slip rates of up to 1 m/s at different normal stresses. Experiments were conducted in a 1-atm, high-velocity friction apparatus at the Istituto Nazionale di Geofisica e Vulcanologia in Rome. A sample consisted of a pair of hollow cylinders of Westerly granite or Frederick diabase subjected to a nominally constant normal stress of from 1 to 30 MPa and subjected to a variety of rate-stepping sequences. Data were acquired at rates of up to 1 MHz. As predicted, the experiments demonstrate that the degree of weakening due to flash heating saturates at slip rates approaching 1 m/s; in a few cases, friction even increases slightly with increasing slip rate near 1 m/s. The experiments also demonstrate that, within the scatter of the data, the value of Vw and the friction coefficient in the weakened state is independent of normal stress, the expected result if average contact sizes and contact stresses are independent of normal stress. The data thus further corroborate existing theories and experimental data for flash heating, allowing for a more reliable determination of the conditions under which flash heating is expected to occur in nature.

Goldsby, D. L.; Spagnuolo, E.; Smith, S. A.; Beeler, N. M.; Tullis, T. E.; Di Toro, G.; Nielsen, S. B.

2012-12-01

369

Interseismic Displacements: Cycle Invariance, Slip Rate, and Rheology  

NASA Astrophysics Data System (ADS)

Geodetic data are commonly interpreted in terms of strain accumulation on faults. Often such interpretations are guided by simple models of interseismic displacements near an infinite strike slip fault (e.g. Savage and Prescott, 1978). These models assume relatively simple rheologies and that the system is in a cycle invariant state, with periodic ruptures such that the displacements throughout the seismic cycle do not vary from one cycle to the next. The displacements are given by perturbations to an average arctangent displacement profile, parameterized by the slip rate and locking depth of the fault. We explore the relationship between cycle invariance, changes in slip rate, and rheology to inferences of slip rate, locking depth, and rheology in models of infinite faults with given histories and sizes of ruptures. The number of seismic cycles required to attain cycle invariance is a function of the strength of the system (parameterized by the Maxwell relaxation time, ? M) and the recurrence time of the ruptures (period, T). In systems with ? M << T the invariant average arctangent curve is established over very few seismic cycles. However, for ? M ? T or ? M > T, it takes many seismic cycles to establish cycle invariance. A consequence of this is that it is easy to confuse a large postseismic relaxation signal (low ? M) calculated ignoring all but the latest earthquake with a periodic system and a small post-seismic relaxation signal (high ? M). During transition to cycle invariance, the average stress level of the system changes by an amount ? ? , determined by ? M, T, and the stress drop in a rupture (? eq); ? ? is independent of the magnitude of the initial background stress. For low ? M, ? ? is negligible compared to ? eq, but may be much larger than ? eq for high ? M. A change in slip rate on a fault, accommodated by a change in recurrence time or ? eq, tends to force the system toward a new average stress. For weak rheologies, changes in slip rate are negligible as the system establishes cycle invariance quickly. However, for stronger rheologies, it takes many seismic cycles to attain cycle invariance, and during the non-invariant transitional time, inferences of slip rate, locking depth, and rheology will be incorrect.

Hetland, E. A.; Hager, B. H.

2003-12-01

370

Airborne Antenna System for Minimum-Cycle-Slip GPS Reception  

NASA Technical Reports Server (NTRS)

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

Wright, C. Wayne

2009-01-01

371

Fault-Wear Under Constant Slip-Velocity: Experimental Observations  

NASA Astrophysics Data System (ADS)

Fault wear, which is a natural result of frictional slip, is a complex process that depends on rock properties (e.g., roughness, brittleness, hardness, strength, composition), and loading conditions (e.g., normal stress, slip velocity, slip history, temperature). Fault wear is indicated in the field primarily by the occurrence of gouge zones and slickenside striations. Analyses of natural faults suggest that gouge-thickness is proportional to fault-displacement over 6-8 orders of magnitude (Scholz, 1987). Experimental studies of fault-wear, which were mostly conducted under low-velocity and for short slip distances, indicate strong dependency of the wear-rate on normal stress. Our experimental study of fault-wear was conducted with a rotary shear apparatus that includes continuous monitoring of wear, friction, and temperature at slip velocities of 0.001-1 m/s and large displacements. Samples of Sierra white granite, approximately 7 cm-diameter, were sheared against each other at normal stress ranging between 0.48 and 6.9 MPa and at slip-velocities up to 0.5 m/s. The wear-rate was calculated from the continuously measured closure across the fault blocks, and presented here by the unit W= [(micron of surface wear) / (meter of slip distance)]. We observed three types of experiments: (1) experiments with transient stage of positive wear-rate (closure across the fault); (2) experiments with transient stage of negative wear-rate (dilation across the fault); and (3) experiments with quasi-constant wear-rate with no transient stage. The initial transient stages were followed by a steady-state wear-rate with low intensity of W=0.5-20 ?/m. The positive transient stage of type (1) corresponds to the well-known "running-in" stage of smoothening the initial roughness and high asperities (Wang and Scholz, 1984). The running-in stage in our experiments is characterize with high wear-rate intesntisy (W = 80-250 ?/m) that decays to the low steady-state values. The dilating transient stage of type (2) has negative wear-rate of -1 to -20 ?/m. Both transient stages decays to the steady state stage after slip of 2 to 10m. Synthesis of steady-state wear-rates intensities indicates that they are related to three parameters: (1) the normal stress, (2) the velocity-dependent friction, and (3) the loading power (=slip-velocity * shear-stress=rate of dissipated energy). We found that the wear-rate is linearly proportional to the normal stress, whereas it has more complex relations to the friction. Relating the Wear-rate to the loading power indicates very high intensity of wear-rate in both low and high loading power, and a minimum, low wear-rate under intermediate loading power. We present the first “wear intensity map” for granite, following Lim and Ashby (1967) and Deuis et al. (1997), that presents wear-rate intensity areas (mild, medium and severe) as function of normal stress and slip-velocity. We will discuss these controlling relations and their implications to gouge zones in the field.

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

2010-12-01

372

Supershear Mach-waves expose the fault breakdown slip  

NASA Astrophysics Data System (ADS)

Mikumo et al. (2003) showed that it is possible to estimate the breakdown slip ( Dc) as the slip at the time of the peak slip rate for rupture propagation with subshear speeds. Cruz-Atienza et al. (2009) later attempted to extend this method to extract information about Dc as the displacement at the time of the peak particle velocity from seismic strong-motion records. However, a reasonably accurate estimate of Dc was only possible in a narrow zone adjacent to the fault (typically on the order of hundreds of meters) due to the fast decay with distance from the fault of the seismic energy related to the stress breakdown process. When the rupture propagates with supershear-speeds, on the other hand, this energy is carried much farther away from the fault by Mach waves, in particular Rayleigh Mach waves when rupture reaches the Earth's surface (Dunham and Bhat, 2008). Here, we present a new approach to estimate Dc from strong-motion records containing Mach waves. First, we show that the method by Mikumo et al. is valid for supershear rupture propagation. This method is then used to estimate Dc via an asymptotic approximation of the slip and slip-rate time histories from the Mach waves. Using spontaneous rupture simulations we demonstrate that, for a visco-elastic half-space model, Dc can be estimated within an error of 40% from Mach waves that have propagated a distance of at least 3 km from the fault. The method is applied to estimate Dc for the 2002 Mw7.9 Denali, Alaska, earthquake (˜ 1.5 m) and for the 1999 Mw7.6 Izmit, Turkey, earthquake (˜ 1.7 m).

Cruz-Atienza, Víctor M.; Olsen, Kim B.

2010-10-01

373

Interior Stokes flows with stick-slip boundary conditions  

NASA Astrophysics Data System (ADS)

Two-dimensional Stokes flows generated by line singularities inside a circular cylinder are studied in the presence of stick-slip boundary conditions. For simplicity, line singularities are assumed to be parallel to the cylinder axis, all axes in the same plane. The interior boundary value problem associated with these flows is solved in terms of a stream function. Analytic solutions are obtained for flows induced by a rotlet, a potential-source and Stokeslets with axes radial (normal) or tangential to the cylinder by the Fourier expansion method. These solutions are used to plot streamline topologies of these flows and the flow patterns are studied as the slip parameter and the locations of the singularities are varied. Eddies of various sizes and shapes appear as the slip parameter is varied. Interesting flow patterns are observed in flows generated by a pair of rotlets. In this case, streamline patterns reveal interesting flow topologies. Some of the flow patterns observed here are similar to that of vortex mixing flows. Interior saddle points are found in these flows for certain values of the slip parameter and locations of the rotlets. The flows induced by a source and a sink and a pair of Stokeslets also exhibit interesting features. The plots of the fluid velocity on the surface of the cylinder show the locations of surface stagnation points, if they exist. A study of the movement of surface stagnation points as the slip parameter and the locations of the singularities are varied shed some light on the qualitative features of the flow patterns. The results presented may be relevant for a variety of applications including vortex mixing and journal bearing flows.

Palaniappan, D.; Daripa, Prabir

2001-08-01

374

Slip velocity of rigid fibers in turbulent channel flow  

NASA Astrophysics Data System (ADS)

In this study, the slip velocity between rigid fibers and a viscous carrier fluid is investigated for the reference case of turbulent channel flow. The statistical moments of the slip velocity are evaluated modelling fibers as prolate spheroids with Stokes number, St, ranging from 1 to 100 and aspect ratio, ?, ranging from 3 to 50. Statistics are compared one-to-one with those obtained for spherical particles (? = 1) to highlight effects due to fiber elongation. Comparison is also made at different Reynolds numbers (Re? =150, 180, and 300 based on the fluid shear velocity) to discuss effects due to an increase of turbulent fluctuations. Results show that elongation has a quantitative effect on slip velocity statistics, particularly evident for fibers with small St. As St increases, differences due to the aspect ratio tend to vanish and the relative translational motion between individual fibers and surrounding fluid is controlled by fiber inertia through preferential concentration. A clear manifestation of inertial effects is the different distribution of slip velocities for fibers trapped in sweep/ejection events and for fibers segregated in near-wall fluid streaks. The corresponding conditional probability distribution functions, shown here for the streamwise and wall-normal slip velocity components, are found to be non-Gaussian, thus suggesting that fiber motion relative to the fluid in high-shear flow regions may not be modelled as a pure diffusion process with constant diffusion coefficient. For the range of simulation parameters investigated, no significant Reynolds number effects are observed, indicating that fiber dynamics exhibit a scaling behavior with respect to the shear velocity up to Re? =300.

Zhao, L.; Marchioli, C.; Andersson, H. I.

2014-06-01

375

LIMITS OF RECOVERY AGAINST SLIP-INDUCED FALLS WHILE WALKING  

PubMed Central

Slip-induced falls in gait often have devastating consequences. The purposes of this study were 1) to select the determinants that can best discriminate the outcomes (recoveries or falls) of an unannounced slip induced in gait (and to find their corresponding threshold, i.e., the limits of recovery, that can clearly separate these two outcomes), and 2) to verify these results in a subset of repeated slip trials. Based on the data collected from 69 young subjects during a slip induced in gait, nine different ways of combining the center of mass (COM) stability, the hip height, and its vertical velocity were investigated with the aid of logistic regression. The results revealed that the COM stability (s) and limb support (represented by the quotient of hip vertical velocity and hip height, Ship) recorded at the instant immediately prior to the recovery step touchdown were sufficiently sensitive to account for all (100%) variance in falls, and specific enough to account for nearly all (98.3%) variability in recoveries. This boundary (Ship = -0.22s -0.25), which quantifies the risk of falls in the stability-limb support quotient (s-Ship) domain, was fully verified using 76 second- and third-slip trials with classification of falls at 100% and recoveries at 98.6%. The severity of an actual fall is likely to be greater further below the boundary, while the likelihood of a fall diminishes above it. Finally, the slope of the boundary also indicates the tradeoff between the stability and limb support, whereby high stability can compensate for the insufficiency in limb support, or vice versa.

Yang, Feng; Bhatt, Tanvi; Pai, Yi-Chung

2012-01-01

376

Distribution of Slip at the Northern Sumatran Fault System  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

377

Triggered surface slips in the Salton Trough associated with the 1999 Hector Mine, California, earthquake  

USGS Publications Warehouse

Surface fracturing occurred along the southern San Andreas, Superstition Hills, and Imperial faults in association with the 16 October 1999 (Mw 7.1) Hector Mine earthquake, making this at least the eighth time in the past 31 years that a regional earthquake has triggered slip along faults in the Salton Trough. Fractures associated with the event formed discontinuous breaks over a 39-km-long stretch of the San Andreas fault, from the Mecca Hills southeastward to Salt Creek and Durmid Hill, a distance from the epicenter of 107 to 139 km. Sense of slip was right lateral; only locally was there a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 13 mm. Maximum slip values in 1999 and earlier triggered slips are most common in the central Mecca Hills. Field evidence indicates a transient opening as the Hector Mine seismic waves passed the southern San Andreas fault. Comparison of nearby strong-motion records indicates several periods of relative opening with passage of the Hector Mine seismic wave-a similar process may have contributed to the field evidence of a transient opening. Slip on the Superstition Hills fault extended at least 9 km, at a distance from the Hector Mine epicenter of about 188 to 196 km. This length of slip is a minimum value, because we saw fresh surface breakage extending farther northwest than our measurement sites. Sense of slip was right lateral; locally there was a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 18 mm, with the largest amounts found distributed (or skewed) away from the Hector Mine earthquake source. Slip triggered on the Superstition Hills fault commonly is skewed away from the earthquake source, most notably in 1968, 1979, and 1999. Surface slip on the Imperial fault and within the Imperial Valley extended about 22 km, representing a distance from the Hector Mine epicenter of about 204 to 226 km. Sense of slip dominantly was right lateral; the right-lateral component of slip ranged from 1 to 19 mm. Locally there was a minor (~1-2 mm) vertical component of slip; larger proportions of vertical slip (up to 10 mm) occurred in Mesquite basin, where scarps indicate long-term oblique-slip motion for this part of the Imperial fault. Slip triggered on the Imperial fault appears randomly distributed relative to location along the fault and source direction. Multiple surface slips, both primary and triggered slip, indicate that slip repeatedly is small at locations of structural complexity.

Rymer, M. J.; Boatwright, J.; Seekins, L. C.; Yule, J. D.; Liu, J.

2002-01-01

378

[Diseases of the hip joint in childhood and adolescence--ultrasonic differential diagnoses].  

PubMed

A total of 329 children with hip pain were examined by ultrasound, which indicated transient synovitis (n = 161), rheumatoid arthritis (n = 16), tuberculoid arthritis (n = 3), septic arthritis (n = 16), Legg-Calvé-Perthes disease (n = 102), and slipped capital femoral epiphysis (n = 31). Using the standard planes described by DEGUM and DGOOC, it is possible to analyze the joint capsule, the surface of the femoral head, and the periarticular structures. In cases of synovitis or joint effusion, a capsular distension can be diagnosed by ultrasound. This distension is typical in transient synovitis, septic and tuberculoid arthritis, juvenile rheumatoid arthritis, and the onset phase of Perthes disease. Because capsular distension exhibits no significant differences in the various diseases, differentiation is not possible with ultrasound in the absence of osseous abnormalities. In cases with both capsular distension and osseous abnormalities, ultrasound usually allows a differentiation between slipped capital femoral epiphysis and Perthes disease as well as septic and unspecific arthritis. PMID:12017857

Konermann, W; Gruber, G

2002-03-01

379

Slip and Dilation Tendency Analysis of the Patua Geothermal Area  

DOE Data Explorer

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 ...

James E. Faulds

380

Slip and Dilation Tendency Analysis of the Patua Geothermal Area  

SciTech Connect

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 ...

James E. Faulds

2013-12-31

381

A theoretical study of stress induced slip at polymer-polymer interfaces  

NASA Astrophysics Data System (ADS)

The phenomena of stress-induced tangential slip at interfaces between immiscible polymer melts is studied by analytic theory and simulation. Characteristic interfacial slip velocities are predicted, at which the interfacial stress behavior qualitatively changes. Interfacial stress is found to be primarily governed by the slip direction alignment of interfacially entangled strands, and the convective release of interfacial entanglements. Simulations combine a slip-link description of polymer entanglement with a self-consistent field description of a polymer-polymer interface.

Gustafson, Andrew Aaron

382

Constraining the relation between tremor and slow slip using tremor distributions and PBO strainmeter data  

Microsoft Academic Search

The relationship between tremor and slow slip can be viewed in the context of a rate-and-state formulation. The expected distribution of slip rate inside a slow slip pulse exhibits a large slip rate in the leading front that decays back towards the healing front. We stacked along-strike tremor distributions on the advancing tremor fronts for 6 major Cascadia ETS events,

B. Delbridge; H. Houston

2010-01-01

383

A simplified method for determining the number of independent slip systems in crystals  

NASA Technical Reports Server (NTRS)

A novel method for determining the number of independent slip systems for any family or a combination of families of slip systems is proposed, which is more direct than previous approaches. This technique makes it possible to easily determine, from the known operative slip systems, if the material is slip-system-deficient. The method also makes it possible to determine if twinning may contribute additional deformation modes.

Cotton, J. D.; Kaufman, M. J.; Noebe, R. D.

1991-01-01

384

MISR JOINT_AS Data  

MISR Data and Information Joint Aerosol Product (JOINT_AS) The MISR Level 3 Products are ... campaigns at daily and monthly time scales. The Joint Aerosol product provides a monthly global statistical summary of MISR Level 2 ...

2014-03-24

385

Cover For Duct Expansion Joint  

NASA Technical Reports Server (NTRS)

Size and shape of cover reduces stress and increases strength. Cover for expansion joints on duct-work seals tightly while accommodating movement of joint. Provides ample bonding area on both members of joint.

Brown, A. R.

1988-01-01

386

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

USGS Publications Warehouse

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.

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

2005-01-01

387

Development of Surface Structures for Large Effective Slip: How Much Slip Is Possible in Ideal, Lab and Real Conditions?  

Microsoft Academic Search

An ideal condition to reduce the drag of a liquid flowing on a solid surface is maintaining a lubricating gas layer between the solid and the liquid. For water flowing on a 1 or 10 mum-thick air layer, for example, the slip length is calculated to be roughly 50 or 500 mum, respectively - large enough to benefit a wide

Chang-Jin Kim

2009-01-01

388

Simultaneous Dislocation of Radiocapitellar and Distal Radioulnar Joint  

PubMed Central

A 45-year-old male presented to the emergency room of our institution complaining of severe pain around the left elbow. While playing volleyball, he slipped down with his left arm hit between the floor and his body. He complaind of strong pain from left elbow to hand, and active motion of elbow and wrist joint was impossible. His forearm was held in supinated position. On X-ray examination, radius head was deviated to anterior lateral side, and distal end of radius was dislocated to dorsal side. Tenderness was prominent at the site of radial head and distal radioulnar joint. Surgical treatment was performed using triceps tendon strip. Good functional recovery was gained.

Nishi, Tomio; Suzuki, Noriyuki; Tani, Takayuki

2013-01-01

389

Appendicular joint dislocations.  

PubMed

This study defines the incidence and epidemiology of joint dislocations and subluxations of the appendicular skeleton. All patients presenting acutely to hospital with a dislocation or subluxation of the appendicular skeleton from a defined population were included in the study. There were 974 dislocations or subluxations over one year between the 1st November 2008 and the 31st October 2009. There was an overall joint dislocation incidence of 157/10(5)/year (188/10(5)/year in males and 128/10(5)/year in females). Males demonstrated a bimodal distribution with a peak incidence of 446/10(5)/year at 15-24 years old and another of 349/10(5)/year in those over 90 years. Females demonstrate an increasing incidence from the seventh decade with a maximum incidence of 520/10(5)/year in those over 90 years. The most commonly affected joints are the glenohumeral (51.2/10(5)/year), the small joints of the hand (29.9/10(5)/year), the patellofemoral joint (21.6/10(5)/year), the prosthetic hip (19.0/10(5)/year), the ankle (11.5/10(5)/year), the acromioclavicular joint (8.9/10(5)/year) and the elbow (5.5/10(5)/year). Unlike fractures, dislocations are more common in the both the most affluent and the most socially deprived sections of the population. Joint disruptions are more common than previously estimated. PMID:23433660

Hindle, Paul; Davidson, Eleanor K; Biant, Leela C; Court-Brown, Charles M

2013-08-01

390

Pressure vessel flex joint  

NASA Technical Reports Server (NTRS)

An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

Kahn, Jon B. (inventor)

1992-01-01

391

Tsunami potential of major restraining bends along sub-marine strike-slip faults  

Microsoft Academic Search

Abstract. Strike-slip faults, with mostly horizontal displacements, are rarely considered capable sources of destructive tsunami. Real strike-slip faults are sinuous, however, with curved and offset traces where local areas of uplift or subsidence occur. At fault bends or offsets where the lateral slip is restrained, seafloor uplift during large submarine earthquakes may generate locally destructive tsunami. To investigate tsunami potential

M. R. Legg; J. C. Borrero

2001-01-01

392

Flow Properties of Majolica Slip with a Thinning Additive Based on Sodium Polyacrylate  

Microsoft Academic Search

The effect of a new thinning agent, namely 40% sodium polyacrylate (SPA), on flow properties of majolica slip and the effect of hardness of water on changes in suspension moisture are considered. The use of 40% SPA makes it possible to reduce its content in slip by nearly half, compared to sodium silicate solution, to improve the slip flow properties,

N. S. Yugai; E. V. Klimova

2004-01-01

393

Flow with Slip Between Coaxial Cylinders and in an Equilateral Triangular Pipe  

Microsoft Academic Search

The Navier-Stokes equations are solved exactly, assuming the Navier slip boundary condition, for flow between coaxial circular cylinders (with possibly different slip lengths at the inner and outer walls), and flow in an equilateral triangular pipe. The velocity fields and total flow rates are found analytically. A relatively small slip length can lead to a large increase in the total

John Lekner

2009-01-01

394

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

USGS Publications Warehouse

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.

Peng, Zhigang; Gomberg, Joan

2010-01-01

395

Output feedback controller for cycle slipping in phase-controlled system  

Microsoft Academic Search

This paper concerns the problem of cycle slipping for continuous phase-controlled systems with periodic nonlinearity. The number of slipped cycles is an important property in transient mode of such nonlinear systems. Based on Yakubovich-Kalman Lemma, LMI characterizations are derived for the number of slipped cycles of such systems and an efficient way for the estimation of the number is proposed

Pingli Lu; Ying Yang; Lin Huang

2007-01-01

396

Slip Rates along the Yunnan Fault Zones Estimated From Repeating Microearthquakes  

Microsoft Academic Search

Fault slip rate has been widely estimated by geologic and geodetic observations. Most of the geologic and geodetic observations are, however, surficial measurements which require an assumed rheology to estimate the slip rate at seismogenic depth. The discovery of repeating microearthquakes has provided a new means for inferring the slip rate at depth along active faults as well as for

Q. Chen; L. Li; F. Niu

2008-01-01

397

A NEW MACRO ELEMENT OF REINFORCED CONCRETE BEAM-COLUMN JOINT FOR ELASTOPLASTIC PLANE FRAME ANALYSIS  

Microsoft Academic Search

This paper proposes a new macro element for the modeling of a reinforced concrete beam-column joints in elasto-plastic plane frame analysis. The macro element defines the nonlinear constitutive relationship between four nodes, each having three degrees of freedom, i.e. two translational displacements and one rotation. The macro element consists of axial springs representing concrete, reinforcement or bond slip behavior considering

Seitaro Tajiri; Hitoshi Shiohara; Fumio Kusuhara

2006-01-01

398

Development of Surface Structures for Large Effective Slip: How Much Slip Is Possible in Ideal, Lab and Real Conditions?  

NASA Astrophysics Data System (ADS)

An ideal condition to reduce the drag of a liquid flowing on a solid surface is maintaining a lubricating gas layer between the solid and the liquid. For water flowing on a 1 or 10 ?m-thick air layer, for example, the slip length is calculated to be roughly 50 or 500 ?m, respectively - large enough to benefit a wide range of engineering applications. Unfortunately, however, the above ideal water-levitating condition is only imaginary, because such a liquid-gas meniscus cannot be sustained in nature. Instead, water-repelling structured surfaces bring us closer to the imaginary condition by minimizing the liquid-solid interface and keeping the water mostly on a layer of air. The underlying goal in developing a large-slip surface is, therefore, to create a condition as close as possible to the uniform air lubrication, which is often overlooked. For example, while a large contact angle on a superhydrophobic surface helps keep the liquid fakir, note that once levitated, the contact angle has little effect on increasing the slip length. Instead, the geometrical parameters of the surface structures, e.g., air fraction, pitch and depth of the structures, are the determining factors. A series of development efforts to create surfaces that bring us closer to the ideal air-lubricating condition will be presented, with the slip length currently measured as large as 400 ?m. However, it will be also noted that they are valid only in laboratory conditions, where the sample is fabricated to near perfection and the pressure in the flowing liquid is under strict control. In real-life engineering conditions, which include high and fluctuating pressure, defective surfaces, and liquids full of impurities and particles, it remains to be seen if we will ever be able to create a slip surface that can be field-deployed - a millennium-old dream.

Kim, Chang-Jin

2009-11-01

399

Compliant Joints For Robots  

NASA Technical Reports Server (NTRS)

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.

Kerley, James J., Jr.

1990-01-01

400

Analysis of the slow slip events of Guerrero, Mexico: implications for numerical modeling.  

NASA Astrophysics Data System (ADS)

Guerrero, in Mexico, is one of the subduction zones where long term slow slip events (SSEs) have been observed recurrently. Understanding the mechanics of these events is important to determine their role in the seismic cycle. SSEs in Guerrero have been found to have the same characteristics, along the interface of subduction, as classical earthquakes but with much longer slip time (around a year) and lower stress drop (0.1 MPa). We investigate the slip models of the Guerrero SSEs of 2006 and 2009 (Radiguet et al., JGR 2012). The kinematic slip models have been determined by inversion of GPS time series using two different methods. From these slip histories, the constitutive relation between stress and slip (or slip rate) on each subfault is determined. Analytical Green functions are used to calculate the shear stress in a homogeneous, elastic, isotropic medium. Whatever the kinematic slip modeling method used, a clear slip weakening law can be retrieved over the whole slipping area. While some spatial variation in the parameters of the slip weakening law is observed, a mean value of about 0.1 m for the slip weakening distance and 2.5 kJ/m2 for the fracture energy can be extracted on each subfault. Moreover the slip-weakening rate seems quite homogeneous (around 1 MPa/m), and this is roughly the same as the value found in coseismic processes. The yield stress is of the order of 0.01 MPa, a low value compared to a stress drop of 0.1 MPa. The stress-slip rate relationship presents a loop trajectory coherent with the one observed in classical earthquakes. The results of these analyses are used to numerically model the Guerrero SSEs. The aim is to reproduce the slip pattern using the mechanical laws determined in the study of the slip model. If a simple slip weakening law, with parameters found above, is used, we observe a rapid progress of the crack-like slip area. This is different from the observation of the migration of localized slip. So a slowing mechanism (healing) must be introduced in addition to the slip weakening law. A pseudo-dynamic model is developed, supposing a fully plastic fault strengthening with a prefixed slip distance.

Maury, Julie; Aochi, Hideo; Radiguet, Mathilde

2014-05-01

401

Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area  

DOE Data Explorer

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...

James E. Faulds

402

Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area  

SciTech Connect

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