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Sample records for tube-in-tube slip joint

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

    SciTech Connect

    Mulcahy, T.M.

    1985-08-01

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

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

    SciTech Connect

    Mulcahy, T.M.

    1983-06-01

    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.

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

    SciTech Connect

    Mulcahy, T.M.

    1984-01-01

    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.

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

    SciTech Connect

    Mulcahy, T.M.

    1986-03-01

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

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

    SciTech Connect

    Mulcahy, T.M.

    1986-12-01

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

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

    SciTech Connect

    Mulcahy, T.M.

    1986-01-01

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

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

    SciTech Connect

    Mulcahy, T.M.

    1985-01-01

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

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

    SciTech Connect

    Mulcahy, T.M.

    1984-10-01

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

  9. Free vibration analysis for tube-in-tube tall buildings

    NASA Astrophysics Data System (ADS)

    Lee, Wen-Hae

    2007-06-01

    An approximate solution procedure is formulated for free vibration analysis of tube-in-tube tall buildings in this paper. The governing partial differential equation of motion is reduced to an ordinary differential equation with variable coefficients on the assumption that the transverse displacement is a harmonic vibration. A power-series solution which represents the mode shape function of tube-in-tube tall buildings is derived. Applying the boundary conditions yields the boundary value problem, from which the frequency equation is established and solved through a numerical process to determine the natural frequencies. Two numerical examples are performed and compared with results available in the published literature to show the accuracy of the proposed method. Care has been exercised to retain sufficient terms in power series in evaluating natural frequencies of accepted accuracy. The influences of the factors including flexural rigidity, mass per unit length and building height to the natural frequency are discussed. The method proposed herein enables one to calculate as an alternative the natural frequency of tube-in-tube tall buildings with good accuracy associated by calculators and hand, prior to use of the complicated computer programs.

  10. Conceptual optimization using genetic algorithms for tube in tube structures

    SciTech Connect

    Pârv, Bianca Roxana; Hulea, Radu; Mojolic, Cristian

    2015-03-10

    The purpose of this article is to optimize the tube in tube structural systems for tall buildings under the horizontal wind loads. It is well-known that the horizontal wind loads is the main criteria when choosing the structural system, the types and the dimensions of structural elements in the majority of tall buildings. Thus, the structural response of tall buildings under the horizontal wind loads will be analyzed for 40 story buildings and a total height of 120 meters; the horizontal dimensions will be 30m × 30m for the first two optimization problems and 15m × 15m for the third. The optimization problems will have the following as objective function the cross section area, as restrictions the displacement of the building< the admissible displacement (H/500), and as variables the cross section dimensions of the structural elements.

  11. Stick-slip friction and wear of articular joints

    PubMed Central

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

    2013-01-01

    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. PMID:23359687

  12. EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR

    EPA Science Inventory

    The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

  13. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMIDAZOLE DERIVATIVES USING A SPINNING TUBE-IN-TUBE REACTOR

    EPA Science Inventory

    The high purity, high throughput synthesis of a number of imidazole derivatives using a spinning tube-in-tube reactor (STT®, Kreido Laboratories, Camarillo California) has been carried out. The STT® reactor allows the high throughput production of high purity imidazole derivativ...

  14. 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...

  15. Hysteresis modeling of clamp band joint with macro-slip

    NASA Astrophysics Data System (ADS)

    Qin, Zhaoye; Cui, Delin; Yan, Shaoze; Chu, Fulei

    2016-01-01

    Clamp band joints are commonly used to connect spacecrafts with launch vehicles. Due to the frictional slippage between the joint components, hysteresis behavior might occur at joint interfaces under cyclic loading. The joint hysteresis will bring friction damping into the launching systems. In this paper, a closed-form hysteresis model for the clamp band joint is developed based on theoretical and numerical analyses of the interactions of the joint components. Then, the hysteresis model is applied to investigating the dynamic response of a payload fastened by the clamp band joint, where the nonlinearity and friction damping effects of the joint is evaluated. The proposed analytical model, which is validated by both finite element analyses and quasi-static experiments, has a simple form with sound accuracy and can be incorporated into the dynamic models of launching systems conveniently.

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

    SciTech Connect

    Luttrell, C R

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  18. 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...

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

    PubMed

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

    2015-02-17

    reactive gas in a given reaction mixture. We have developed a tube-in-tube reactor device consisting of a pair of concentric capillaries in which pressurized gas permeates through an inner Teflon AF-2400 tube and reacts with dissolved substrate within a liquid phase that flows within a second gas impermeable tube. This Account examines our efforts toward the development of a simple, unified methodology for the processing of gaseous reagents in flow by way of development of a tube-in-tube reactor device and applications to key C-C, C-N, and C-O bond forming and hydrogenation reactions. We further describe the application to multistep reactions using solid-supported reagents and extend the technology to processes utilizing multiple gas reagents. A key feature of our work is the development of computer-aided imaging techniques to allow automated in-line monitoring of gas concentration and stoichiometry in real time. We anticipate that this Account will illustrate the convenience and benefits of membrane tube-in-tube reactor technology to improve and concomitantly broaden the scope of gas/liquid/solid reactions in organic synthesis. PMID:25611216

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

    PubMed Central

    Liu, Jian; Lockhart, Thurmon E.

    2013-01-01

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

  1. Automated library synthesis of cyclopropyl boronic esters employing diazomethane in a tube-in-tube flow reactor.

    PubMed

    Koolman, Hannes F; Kantor, Stanislaw; Bogdan, Andrew R; Wang, Ying; Pan, Jeffrey Y; Djuric, Stevan W

    2016-07-01

    The efficient synthesis of cyclopropyl boronic esters in library format using a diazomethane flow reactor has been achieved. A pivotal component of the system is a fully automated tube-in-tube reactor allowing for safe handling of hazardous diazomethane on repeated small scale and for the generation of larger quantities of product. The setup enables the repeated execution of Pd-catalyzed cyclopropanation reactions without compromising its operation over time. PMID:27314279

  2. Catalytic Chan-Lam coupling using a 'tube-in-tube' reactor to deliver molecular oxygen as an oxidant.

    PubMed

    Mallia, Carl J; Burton, Paul M; Smith, Alexander M R; Walter, Gary C; Baxendale, Ian R

    2016-01-01

    A flow system to perform Chan-Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times. PMID:27559412

  3. Erythorbic acid promoted formation of CdS QDs in a tube-in-tube micro-channel reactor

    SciTech Connect

    Liang, Yan; Tan, Jiawei; Wang, Jiexin; Chen, Jianfeng; Sun, Baochang; Shao, Lei

    2014-12-15

    Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    PubMed

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

    2008-05-21

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

  6. 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...

  7. Encapsulating MWNTs into hollow porous carbon nanotubes: a tube-in-tube carbon nanostructure for high-performance lithium-sulfur batteries.

    PubMed

    Zhao, Yi; Wu, Wangliang; Li, Jiaxin; Xu, Zhichuan; Guan, Lunhui

    2014-08-13

    A tube-in-tube carbon nanostructure (TTCN) with multi-walled carbon nanotubes (MWNTs) confined within hollow porous carbon nanotubes is synthesized for Li-S batteries. The structure is designed to enhance the electrical conductivity, hamper the dissolution of lithium polysulfide, and provide large pore volume for sulfur impregnation. As a cathode material for Li-S batteries, the S-TTCN composite with 71 wt% sulfur content delivers high reversible capacity, good cycling performance as well as excellent rate capabilities. PMID:24897930

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

    SciTech Connect

    Li, Juan; Que, Tingli; Huang, Jianbin

    2013-02-15

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

  9. Influence of the bond-slip relationship on the flexural capacity of R.C. joints damaged by corrosion

    NASA Astrophysics Data System (ADS)

    Imperatore, Stefania

    2016-06-01

    In moderate and aggressive environmental condition, old reinforced concrete structures are often subjected to corrosive phenomena. Corrosion causes cracking, loss of diameter in reinforcement and variation of the bond behavior between steel and concrete. Then, in presence of cyclic actions like the seismic ones, old R.C. elements vary their ultimate drift, ductility, plastic rotation capacity and energy dissipation with the corrosion level. The problem is of current interest: the issue has been introduced in some paragraph of the Model Code 2010 and a committee is now drafting a new document on assessment strategies on existing concrete structures also damaged by corrosion. In this work, a first step on the analysis of the impact of the corrosion on the seismic behavior of R.C. elements is assessed: by mean FEM analyses, of a poor detailed column/foundation joint is analyzed in a parametric way in order to evaluate the influence of the bond-slip degradation by corrosion on the element flexural capacity.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  11. Coseismic slip distribution of the 2015 Mw7.8 Gorkha, Nepal, earthquake from joint inversion of GPS and InSAR data for slip within a 3-D heterogeneous Domain

    NASA Astrophysics Data System (ADS)

    Tung, Sui; Masterlark, Timothy

    2016-05-01

    We derive a coseismic slip model of the 2015 Mw7.8 Gorkha earthquake on the basis of GPS and line-of-sight displacements from ALOS-2 descending interferograms, using Green's functions calculated with a 3-D finite element model (FEM). The FEM simulates a nonuniform distribution of elastic material properties and a precise geometric configuration of the irregular topographical surface. The rupturing fault is modeled as a low-angle and north dipping surface within the Main Frontal Thrust along the convergent margin of the Himalayas. The optimal model that inherits heterogeneous material properties provides a significantly better solution than that in a homogenous domain at the 95% confidence interval. The best fit solution for the domain having a nonuniform distribution of material properties reveals a rhombus-shaped slip zone of three composite asperities. Slip is primarily concentrated at a depth of 15 km with both dip-slip (maximum 6.54 m) and strike-slip (maximum 2.0 m) components, giving rise to a geodetic-based moment of 1.09 × 1021 Nm in general agreement with the seismological estimate. The optimal relative weights among GPS and interferometric synthetic aperture radar (InSAR) are deduced from a new method, MC-HVCE which combines a Monte Carlo search and a Helmert Method of Variance Components Estimation. This method determines the relative weights in a systemic approach which preserves the intrinsic solution smoothness. The joint solution is significantly better than those inverted from each individual data set. This methodology allows us to integrate multiple data sets of geodetic observations with seismic tomography, in an effort to achieve a better understanding of seismic ruptures within crustal heterogeneity.

  12. Slipped capital femoral epiphysis

    MedlinePlus

    A slipped capital femoral epiphysis is a separation of the ball of the hip joint from the thigh bone (femur) at ... A slipped capital femoral epiphysis may affect both hips. An epiphysis is an area at the end of a long bone . ...

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

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Burgmann, R.

    2011-12-01

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

  14. Triggered slip on a back reverse fault in the Mw6.8 2013 Lushan, China earthquake revealed by joint inversion of local strong motion accelerograms and geodetic measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Guohong; Hetland, Eric A.; Shan, Xinjian; Vallée, Martin; Liu, Yunhua; Zhang, Yingfeng; Qu, Chunyan

    2016-03-01

    The 2013 Mw6.8 Lushan, China earthquake occurred in the southwestern end of the Longmenshan fault zone. We jointly invert local strong motion data and geodetic measurements of coseismic surface deformation, including GPS and InSAR, to obtain a robust model of the rupture process of the 2013 Lushan earthquake. Our joint inversion best model involves the rupture of two opposing faults during the Lushan earthquake, a main fault and a secondary fault. It is only when the secondary fault is included that both the GPS and InSAR measurements are fit along with the near-field strong motion. Over 75% of the computed moment was released in slip on the main fault segment, a northwest dipping, listric thrust fault, with buried thrust and dextral strike-slip at hypocenter depths, and with only minor slip closer to the surface. The secondary fault mainly involved oblique thrust slip or pure dextral strike-slip at shallower depths, and accounts for just under 24% of the moment released in the Lushan earthquake. Coulomb stress changes of about 0.5 MPa on the secondary fault segment at the time coseismic slip initiated on that fault indicate that slip was likely triggered by the coseismic slip on the main blind thrust fault. Our coseismic slip model is consistent with a sub-horizontal and east-west to southeast-northwest trending most compressive stress. Our inferred coseismic slip model is also consistent with previous GPS derived models of strain accumulation on the Longmenshan fault system.

  15. Implementing a C++ Version of the Joint Seismic-Geodetic Algorithm for Finite-Fault Detection and Slip Inversion for Earthquake Early Warning

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Felizardo, C.; Minson, S. E.; Boese, M.; Langbein, J. O.; Guillemot, C.; Murray, J. R.

    2015-12-01

    The earthquake early warning (EEW) systems in California and elsewhere can greatly benefit from algorithms that generate estimates of finite-fault parameters. These estimates could significantly improve real-time shaking calculations and yield important information for immediate disaster response. Minson et al. (2015) determined that combining FinDer's seismic-based algorithm (Böse et al., 2012) with BEFORES' geodetic-based algorithm (Minson et al., 2014) yields a more robust and informative joint solution than using either algorithm alone. FinDer examines the distribution of peak ground accelerations from seismic stations and determines the best finite-fault extent and strike from template matching. BEFORES employs a Bayesian framework to search for the best slip inversion over all possible fault geometries in terms of strike and dip. Using FinDer and BEFORES together generates estimates of finite-fault extent, strike, dip, preferred slip, and magnitude. To yield the quickest, most flexible, and open-source version of the joint algorithm, we translated BEFORES and FinDer from Matlab into C++. We are now developing a C++ Application Protocol Interface for these two algorithms to be connected to the seismic and geodetic data flowing from the EEW system. The interface that is being developed will also enable communication between the two algorithms to generate the joint solution of finite-fault parameters. Once this interface is developed and implemented, the next step will be to run test seismic and geodetic data through the system via the Earthworm module, Tank Player. This will allow us to examine algorithm performance on simulated data and past real events.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Joint inversion of broadband teleseismic and interferometric synthetic aperture radar (InSAR) data for the slip history of the Mw = 7.7, Nazca ridge (Peru) earthquake of 12 November 1996

    NASA Astrophysics Data System (ADS)

    Salichon, J.; Delouis, B.; Lundgren, P.; Giardini, D.; Costantini, M.; Rosen, P.

    2003-02-01

    The slip distribution of the 12 November 1996, Mw = 7.7, Peru earthquake is determined using broadband teleseismic waveforms, a differential SAR interferogram (interferometric synthetic aperture radar [InSAR]), and a fault parametrization allowing slip and rupture velocity to vary along the rupture plane. Both data sets are inverted jointly to limit the trade-off between the space and time aspects of the rupture. The earthquake fault plane is located at the subduction interface; it strikes parallel to the trench and dips 30° NE. By inverting synthetic data, we show how the InSAR and teleseismic data are complementary and how the joint inversion produces a gain in the spatial and temporal resolution of the slip model, even with a SAR interferogram that covers only part of the coseismic deformation. The rupture of the 1996 Peru event initiated on the southern flank of the subducted Nazca ridge and propagated unilaterally toward the southeast (along strike) for more than 100 km at a depth between 20 and 40 km. The area of maximum slip (6-7 m) is located 50 km southeast of the hypocenter. The total seismic moment is 4.4 × 1020 N m (our joint inversion). The source time function is approximately 60 s long and presents three major pulses of moment release. The dominant one, which occurred between 30 and 45 s, does not correspond to the area of largest slip but to the rupture of a wide zone located about 100 km away from the hypocenter where slip reaches only 2-3 m. Computed coseismic coastal uplift correlates well with the location of raised marine terraces and with the topography of the coastal cordillera, suggesting that these features may be related to the repetition of 1996-type events at the interface between the Nazca ridge and the South American plate.

  18. 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)

    Bird, P.

    2008-12-01

    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

  19. Slip Kits.

    ERIC Educational Resources Information Center

    Coombes, S. D.

    1979-01-01

    Discusses the process of developing the Science Lessons from Industrial Processes (SLIP) kits by 16 British science teachers. The content, applicability, and components of these kits (based upon local industries) are also included. (HM)

  20. Tube-in-tube thermophotovoltaic generator

    SciTech Connect

    Ashcroft, John; Campbell, Brian; DePoy, David

    1998-01-01

    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.

  1. Tube-in-tube thermophotovoltaic generator

    DOEpatents

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

    1998-06-30

    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.

  2. A tube-in-tube thermophotovoltaic generator

    SciTech Connect

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

    1996-12-31

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  4. The role of pressure solution seam and joint assemblages in the formation of strike-slip and thrust faults in a compressive tectonic setting; The Variscan of south-western Ireland

    NASA Astrophysics Data System (ADS)

    Nenna, Filippo; Aydin, Atilla

    2011-11-01

    The Ross Sandstone in County Clare, Ireland, was deformed by an approximately north-south compression during the end-Carboniferous Variscan orogeny. The initial assemblage consists of mutually abutting orthogonal arrays of 170° oriented set 1 joints/veins (JVs) and approximately 75° oriented set 1 pressure solution seams (PSSs) formed under the same stress conditions. Orientations of splay JVs and PSSs (set 2) suggest a clockwise remote stress rotation of about 35° responsible for the contemporaneous shearing of the set 1 arrays. Among these nearly orthogonal strike-slip faults, the prominent set is sub-parallel to set 1 JVs. These faults are formed by the linkage of en-echelon segments with broad damage zones responsible for right-lateral offsets of hundreds of meters. Thrust faults with up to 30 m of offset initiate within shale horizons and follow either the PSSs in the sandstones or high-angle shales within tilted sequences. Within the large thrust fault zones, compartmentalised blocks of rocks are bounded by thrust faults segments with various dip angles. Strike-slip and thrust faults are contemporaneous and owe their existence to initial weaknesses in the form of JVs and PSSs rather than by switching relative stress magnitudes and orientations associated with Andersonian models of faults and related stress orientations.

  5. Adaptive regularization of earthquake slip distribution inversion

    NASA Astrophysics Data System (ADS)

    Wang, Chisheng; Ding, Xiaoli; Li, Qingquan; Shan, Xinjian; Zhu, Jiasong; Guo, Bo; Liu, Peng

    2016-04-01

    Regularization is a routine approach used in earthquake slip distribution inversion to avoid numerically abnormal solutions. To date, most slip inversion studies have imposed uniform regularization on all the fault patches. However, adaptive regularization, where each retrieved parameter is regularized differently, has exhibited better performances in other research fields such as image restoration. In this paper, we implement an investigation into adaptive regularization for earthquake slip distribution inversion. It is found that adaptive regularization can achieve a significantly smaller mean square error (MSE) than uniform regularization, if it is set properly. We propose an adaptive regularization method based on weighted total least squares (WTLS). This approach assumes that errors exist in both the regularization matrix and observation, and an iterative algorithm is used to solve the solution. A weight coefficient is used to balance the regularization matrix residual and the observation residual. An experiment using four slip patterns was carried out to validate the proposed method. The results show that the proposed regularization method can derive a smaller MSE than uniform regularization and resolution-based adaptive regularization, and the improvement in MSE is more significant for slip patterns with low-resolution slip patches. In this paper, we apply the proposed regularization method to study the slip distribution of the 2011 Mw 9.0 Tohoku earthquake. The retrieved slip distribution is less smooth and more detailed than the one retrieved with the uniform regularization method, and is closer to the existing slip model from joint inversion of the geodetic and seismic data.

  6. Electro-optical hybrid slip ring

    NASA Astrophysics Data System (ADS)

    Hong, En

    2005-11-01

    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

  7. Lower extremity corrective reactions to slip events.

    PubMed

    Cham, R; Redfern, M S

    2001-11-01

    A significant number of injuries in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether the outcome of a slip will be recovery or a fall. The goal of this study was to examine lower extremity joint moments and postural adjustments for experimental evidence of corrective strategies evoked during slipping in an attempt to prevent falling. Sixteen subjects walked onto a possibly oily vinyl tile floor, while ground reaction forces and body motion were recorded at 350 Hz. The onset of corrective reactions by the body in an attempt to recover from slips became evident at about 25% of stance and continued until about 45% into stance, i.e. on average between 190 and 350 ms after heel contact. These reactions included increased flexion moment at the knee and extensor activity at the hip. The ankle, on the other hand, acted as a passive joint (no net moment) during fall trials. Joint kinematics showed increased knee flexion and forward rotation of the shank in an attempt to bring the foot back towards the body. Once again, the ankle kinematics appeared to play a less dominant role (compared to the knee) in recovery attempts. This study indicates that humans generate corrective reactions to slips that are different than previously reported responses to standing perturbations translating the supporting surface. PMID:11672718

  8. Slipped capital femoral epiphysis

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/000972.htm Slipped capital femoral epiphysis To use the sharing features on this page, please enable JavaScript. A slipped capital femoral epiphysis is a separation of the ball ...

  9. Reconsidering Fault Slip Scaling

    NASA Astrophysics Data System (ADS)

    Gomberg, J. S.; Wech, A.; Creager, K. C.; Obara, K.; Agnew, D. C.

    2015-12-01

    The scaling of fault slip events given by the relationship between the scalar moment M0, and duration T, potentially provides key constraints on the underlying physics controlling slip. Many studies have suggested that measurements of M0 and T are related as M0=KfT3 for 'fast' slip events (earthquakes) and M0=KsT for 'slow' slip events, in which Kf and Ks are proportionality constants, although some studies have inferred intermediate relations. Here 'slow' and 'fast' refer to slip front propagation velocities, either so slow that seismic radiation is too small or long period to be measurable or fast enough that dynamic processes may be important for the slip process and measurable seismic waves radiate. Numerous models have been proposed to explain the differing M0-T scaling relations. We show that a single, simple dislocation model of slip events within a bounded slip zone may explain nearly all M0-T observations. Rather than different scaling for fast and slow populations, we suggest that within each population the scaling changes from M0 proportional to T3 to T when the slipping area reaches the slip zone boundaries and transitions from unbounded, 2-dimensional to bounded, 1-dimensional growth. This transition has not been apparent previously for slow events because data have sampled only the bounded regime and may be obscured for earthquakes when observations from multiple tectonic regions are combined. We have attempted to sample the expected transition between bounded and unbounded regimes for the slow slip population, measuring tremor cluster parameters from catalogs for Japan and Cascadia and using them as proxies for small slow slip event characteristics. For fast events we employed published earthquake slip models. Observations corroborate our hypothesis, but highlight observational difficulties. We find that M0-T observations for both slow and fast slip events, spanning 12 orders of magnitude in M0, are consistent with a single model based on dislocation

  10. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  11. 14 CFR 27.935 - Shafting joints.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Shafting joints. 27.935 Section 27.935... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must...

  12. 14 CFR 29.935 - Shafting joints.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Shafting joints. 29.935 Section 29.935... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation...

  13. 14 CFR 29.935 - Shafting joints.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Shafting joints. 29.935 Section 29.935... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation...

  14. 14 CFR 29.935 - Shafting joints.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Shafting joints. 29.935 Section 29.935... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation...

  15. 14 CFR 27.935 - Shafting joints.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Shafting joints. 27.935 Section 27.935... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must...

  16. 14 CFR 27.935 - Shafting joints.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Shafting joints. 27.935 Section 27.935... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must...

  17. 14 CFR 27.935 - Shafting joints.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Shafting joints. 27.935 Section 27.935... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must...

  18. 14 CFR 29.935 - Shafting joints.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Shafting joints. 29.935 Section 29.935... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation...

  19. 14 CFR 29.935 - Shafting joints.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Shafting joints. 29.935 Section 29.935... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation...

  20. 14 CFR 27.935 - Shafting joints.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Shafting joints. 27.935 Section 27.935... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must...

  1. Slipped Capital Femoral Epiphysis

    MedlinePlus

    ... is held in place with a single central screw. This screw keeps the thigh bone from slipping and will ... including in-situ fixation with more than one screw) are used less often. Ask your doctor to ...

  2. SLIP CASTING METHOD

    DOEpatents

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  3. Inorganic glass ceramic slip rings

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    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.

  4. Long-term fault slip rates, distributed deformation rates, and forecast of seismicity in the western United States from joint fitting of community geologic, geodetic, and stress direction data sets

    NASA Astrophysics Data System (ADS)

    Bird, Peter

    2009-11-01

    The long-term average velocity field of the western United States is computed with a kinematic finite element code. Community data sets include fault traces, geologic offset rates, geodetic velocities, principal stress directions, and Euler poles. There is an irreducible minimum amount of distributed permanent deformation, which accommodates one third of Pacific-North America relative motion in California. Much of this may be due to slip on faults not included in the model. All data sets are fit at a common RMS level of 1.8 datum standard deviations. Experiments with alternate weights, fault sets, and Euler poles define a suite of acceptable community models. In pseudoprospective tests, fault offset rates are compared to 126 additional published rates not used in the computation: 44% are consistent; another 48% have discrepancies under 1 mm a-1, and 8% have larger discrepancies. Updated models are then computed. Novel predictions include dextral slip at 2-3 mm a-1 in the Brothers fault zone, two alternative solutions for the Mendocino triple junction, slower slip on some trains of the San Andreas fault than in recent hazard models, and clockwise rotation of some domains in the eastern California shear zone. Long-term seismicity is computed by assigning each fault and finite element the seismicity parameters (coupled thickness, corner magnitude, and spectral slope) of the most comparable type of plate boundary. This long-term seismicity forecast is retrospectively compared to instrumental seismicity. The western United States has been 37% below its long-term average seismicity during 1977-2008, primarily because of (temporary) reduced activity in the Cascadia subduction zone and San Andreas fault system.

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

    USGS Publications Warehouse

    Segall, P.; Pollard, D.P.

    1983-01-01

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

  6. Slip partitioning by elastoplastic propagation of oblique slip at depth.

    PubMed

    Bowman, David; King, Geoffrey; Tapponnier, Paul

    2003-05-16

    Oblique motion along tectonic boundaries is commonly partitioned into slip on faults with different senses of motion. The origin of slip partitioning is important to structural geology, tectonophysics, and earthquake mechanics. Partitioning can be explained by the upward elastoplastic propagation of oblique slip from a fault or shear zone at depth. The strain field ahead of the propagating fault separates into zones of predominantly normal, reverse, and strike-slip faulting. The model successfully predicts the distribution of fault types along parts of the San Andreas and Haiyuan faults. PMID:12750513

  7. Quantum phase slip noise

    NASA Astrophysics Data System (ADS)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2016-07-01

    Quantum phase slips (QPSs) generate voltage fluctuations in superconducting nanowires. Employing the Keldysh technique and making use of the phase-charge duality arguments, we develop a theory of QPS-induced voltage noise in such nanowires. We demonstrate that quantum tunneling of the magnetic flux quanta across the wire yields quantum shot noise which obeys Poisson statistics and is characterized by a power-law dependence of its spectrum SΩ on the external bias. In long wires, SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T →0 . The quantum coherent nature of QPS noise yields nonmonotonous dependence of SΩ on T at small Ω .

  8. Universal behavior in ideal slip

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. Mechanism of slip and twinning

    NASA Technical Reports Server (NTRS)

    Rastani, Mansur

    1992-01-01

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

  10. Refining the shallow slip deficit

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohua; Tong, Xiaopeng; Sandwell, David T.; Milliner, Christopher W. D.; Dolan, James F.; Hollingsworth, James; Leprince, Sebastien; Ayoub, Francois

    2016-03-01

    Geodetic slip inversions for three major (Mw > 7) strike-slip earthquakes (1992 Landers, 1999 Hector Mine and 2010 El Mayor-Cucapah) show a 15-60 per cent reduction in slip near the surface (depth < 2 km) relative to the slip at deeper depths (4-6 km). This significant difference between surface coseismic slip and slip at depth has been termed the shallow slip deficit (SSD). The large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes. One potential explanation for the SSD is that the previous geodetic inversions lack data coverage close to surface rupture such that the shallow portions of the slip models are poorly resolved and generally underestimated. In this study, we improve the static coseismic slip inversion for these three earthquakes, especially at shallow depths, by: (1) including data capturing the near-fault deformation from optical imagery and SAR azimuth offsets; (2) refining the interferometric synthetic aperture radar processing with non-boxcar phase filtering, model-dependent range corrections, more complete phase unwrapping by SNAPHU (Statistical Non-linear Approach for Phase Unwrapping) assuming a maximum discontinuity and an on-fault correlation mask; (3) using more detailed, geologically constrained fault geometries and (4) incorporating additional campaign global positioning system (GPS) data. The refined slip models result in much smaller SSDs of 3-19 per cent. We suspect that the remaining minor SSD for these earthquakes likely reflects a combination of our elastic model's inability to fully account for near-surface deformation, which will render our estimates of shallow slip minima, and potentially small amounts of interseismic fault creep or triggered slip, which could `make up' a small percentages of the coseismic SSD during the interseismic period. Our results indicate that it is imperative that slip inversions include

  11. Slip flow in graphene nanochannels

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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), 10.1103/PhysRevE.84.016313]. 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.

  12. Formation and Suppression of Strike-Slip Fault Systems

    NASA Astrophysics Data System (ADS)

    Curren, Ivy S.; Bird, Peter

    2014-11-01

    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.

  13. Low-Friction Joint for Robot Fingers

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F.

    1985-01-01

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

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

    PubMed Central

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

    2009-01-01

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

  15. Slipping with the waste (a wheelie bin hand injury).

    PubMed

    Parkes, Rebekah; Weerasuriya, Thisara; Gibson, Suzy

    2015-01-01

    A right hand dominant man in his 60s was moving his wheelie bin when he tripped and landed still holding on to the handle. His hand was trapped between the handle and the ground. He sustained lacerations at the level of the proximal interphalangeal joints of all the fingers of his right hand. The index and middle fingers had damage to the proximal phalangeal articular cartilage and central slip. The central slip loss in the middle finger required reconstruction. The wounds healed without complication by 4 weeks, at which point the patient's fingers were mobilised; he regained almost full range of movement by 3 months. PMID:26126509

  16. Intentional Action and Action Slips.

    ERIC Educational Resources Information Center

    Heckhausen, Heinz; Beckmann, Jurgen

    1990-01-01

    An explanation of action slips is offered that examines controlled actions in the context of an intentional behavior theory. Actions are considered guided by mentally represented intentions, subdivided into goal intentions and contingent instrumental intentions. Action slips are categorized according to problem areas in the enactment of goal…

  17. Suppression of strike-slip fault systems

    NASA Astrophysics Data System (ADS)

    Curren, I. S.

    2012-12-01

    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

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

    SciTech Connect

    DOHNER,JEFFREY L.

    2000-11-06

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

  19. Characterizing the Relationship of Tremor and Slip during Recent ETS Events in Northern Cascadia using Strainmeters, GPS, and Tremor Observations

    NASA Astrophysics Data System (ADS)

    Krogstad, R. D.; Schmidt, D. A.

    2014-12-01

    We investigate the relationship between slip and tremor during multiple recent slow slip events in northern Cascadia. While the relationship of geodetically detectable slow slip and nonvolcanic tremor appears to be broadly coincident, the exact spatial and temporal characteristics remain unclear at a finer scale. Typical GPS derived slip distributions tend to be spatially and temporally smoothed and offset slightly updip of tremor distributions. These discrepancies may be real, or they may be a consequence of the resolution of GPS data or an artifact of the inversion methodology. Borehole strainmeters provide additional independent geodetic constraints for characterizing slip, provide greater temporal resolution, and greater precision than GPS. However, various non-tectonic artifacts and other sources of error have limited the number of usable stations and made deriving reliable information from strainmeters during slip events difficult. We utilize strainmeters with low levels of noise and minimal observable artifacts to constrain forward models and to provide additional independent observations in joint geodetic inversions with GPS data. A series of slip distributions are derived by inverting strainmeter and GPS data using the Kalman-filter-based Extended Network Inversion Filter. To compare the tremor distributions to the geodetically derived slip we also construct slip distributions using tremor occurrences as a proxy for localized slip on the plate interface. The magnitude of slip per tremor occurrence is then scaled to best match the observed surface displacements. Separate slip distributions informed by GPS and tremor are then used to predict strain time series. The comparisons between strain predictions and observations produce mixed results. This may indicate that that tremor and slip are not always coincident. This is particularly evident during the Aug. 2010 event, where the peak GPS-derived slip is located in a region with decreased tremor activity

  20. Slipped capital femoral epiphysis caused by neurogenic heterotopic ossification.

    PubMed

    Chang, Sam Yeol; Yoo, Won Joon; Park, Moon Seok; Chung, Chin Youb; Choi, In Ho; Cho, Tae-Joon

    2013-11-01

    Slipped capital femoral epiphysis (SCFE) is rare in nonambulatory patients, as mechanical factors play important roles in the development of the disease. We report a case of SCFE, which occurred in a 12-year-old girl with a nonambulatory status after cerebral infarction. SCFE occurred after she received passive range of motion exercise and extracorporeal shock wave treatment for neurogenic heterotopic ossification around the hip joint. The patient was successfully managed by a stepwise approach, with radiological and clinical improvements. PMID:23969564

  1. Slipped and lost extraocular muscles.

    PubMed

    Lenart, T D; Lambert, S R

    2001-09-01

    A slipped or lost muscle should be considered in the differential diagnosis of a patient presenting with a marked limitation of duction and inability to rotate the eye beyond the midline. Loss of a rectus muscle can occur after strabismus surgery, trauma, paranasal sinus surgery, orbital surgery, or retinal detachment surgery. The extraocular rectus muscle most frequently slipped or lost is the medial rectus muscle. Forced ductions, active force generation, saccadic velocity studies, differential intraocular pressure measurements, and orbital imaging studies may aid in identifying a slipped or lost muscle. However, no single diagnostic test provides absolute reliability for determining a lost muscle. Slipped muscles develop when the muscular capsule is imbricated without including the muscle or muscle tendon during strabismus surgery. When the capsule is reattached to the sclera, the tendon and muscle are then free to slip posteriorally from the site of attachment. Slipped muscles are retrieved by following the thin avascular muscle capsule posteriorally until the muscle is identified. A lost muscle can be found using a traditional conjunctival approach, by an external orbitotomy, or by an endoscopic transnasal approach. Although many diagnostic maneuvers are useful in identifying a lost rectus muscle, the oculocardiac reflex is the most important. Once the lost muscle is identified, the muscle should be imbricated with a nonabsorbable synthetic suture and securely reattached to the globe. PMID:11705143

  2. Joint swelling

    MedlinePlus

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

  3. Slip of Spreading Viscoplastic Droplets.

    PubMed

    Jalaal, Maziyar; Balmforth, Neil J; Stoeber, Boris

    2015-11-10

    The spreading of axisymmetric viscoplastic droplets extruded slowly on glass surfaces is studied experimentally using shadowgraphy and swept-field confocal microscopy. The microscopy furnishes vertical profiles of the radial velocity using particle image velocimetry (PIV) with neutrally buoyant tracers seeded in the fluid. Experiments were conducted for two complex fluids: aqueous solutions of Carbopol and xanthan gum. On untreated glass surfaces, PIV demonstrates that both fluids experience a significant amount of effective slip. The experiments were repeated on glass that had been treated to feature positive surface charges, thereby promoting adhesion between the negatively charged polymeric constituents of the fluids and the glass surface. The Carbopol and xanthan gum droplets spread more slowly on the treated surface and to a smaller radial distance. PIV demonstrated that this reduced spreading was associated with a substantial reduction in slip. For Carbopol, the effective slip could be eliminated entirely to within the precision of the PIV measurements; the reduction in slip was less effective for xanthan gum, with a weak slip velocity remaining noticeable. PMID:26418827

  4. Stabilizing Stick-Slip Friction

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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).

  5. Whillans Ice Plain Stick Slip

    NASA Astrophysics Data System (ADS)

    Lipovsky, B.; Dunham, E. M.

    2015-12-01

    Concern about future sea level rise motivates the study of fast flowing ice. The Whillans Ice Plain (WIP) region of the West Antarctic Ice Sheet is notable for decelerating from previously fast motion during the instrumental record. Since most ice flux in Antarctica occurs through ice streams, understanding the conditions that cause ice stream stagnation is of basic importance in understanding the continent's contribution to future sea level rise. Although recent progress has been made in understanding the relationship between basal conditions and ice stream motion, direct observation of the temporal variation in subglacial conditions during ice stream stagnation has remained elusive. The Whillans Ice Plain flows to the sea mostly by way of stick-slip motion. We present numerical simulations of this stick-slip motion that capture the inertial dynamics, seismic waves, and the evolution of sliding with rate- and state-dependent basal friction. Large scale stick-slip behavior is tidally modulated and encompasses the entire WIP. Sliding initiates within one of several locked regions and then propagates outward with low average rupture velocity (~ 200 m/s). Sliding accelerates over a period of 200 s attain values as large as 65 m/d. From Newton's second law, this acceleration is ~ T / (rho H) for average shear stress drop T, ice thickness H, and ice density rho. This implies a 3 Pa stress drop that must be reconciled with the final stress drop of 300 Pa inferred from the total slip and fault dimensions. A possible explanation of this apparent discrepancy is that deceleration of the ice is associated with a substantial decrease in traction within rate-strengthening regions of the bed. During these large-scale sliding events, m-scale patches at the bed produce rapid (20 Hz) stick-slip motion. Each small event occurs over ~ 1/100 s, produces ~ 40 microns of slip, and gives rise to a spectacular form of seismic tremor. Variation between successive tremor episodes allows us

  6. Slip-Cast Superconductive Parts

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

    1993-01-01

    Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

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

    SciTech Connect

    Koteras, J.R.

    1991-10-01

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

  8. The evolution of faults formed by shearing across joint zones in sandstone

    NASA Astrophysics Data System (ADS)

    Myers, Rodrick; Aydin, Atilla

    2004-05-01

    The evolution of strike-slip and normal faults formed by slip along joint zones is documented by detailed field studies in the Jurassic Aztec Sandstone in the Valley of Fire State Park, Nevada, USA. Zones of closely spaced planar sub-parallel joints arranged en échelon are sheared, forming faults. Fracturing occurs as a result of shearing, forming new joints. Later shearing along these joints leads to successively formed small faults and newer joints. This process is repeated through many generations of fracturing with increasing fault slip producing a hierarchical array of structures. Strain localization produced by shearing of joint zones at irregularities in joint traces, fracture intersections, and in the span between adjacent sheared joints results in progressive fragmentation of the weakened sandstone, which leads to the formation of gouge along the fault zone. The length and continuity of the gouge and associated slip surfaces is related to the slip magnitude and fault geometry with slip ranging from several millimeters to about 150 m. Distributed damage in a zone surrounding the gouge core is related to the original joint zone configuration (step sense, individual sheared joint overlaps and separation), shear sense, and slip magnitude. Our evolutionary model of fault development helps to explain some outstanding issues concerning complexities in faulting such as, the variability in development of fault rock and fault related fractures, and the failure processes in faults.

  9. Slow-Slip Propagation Speeds

    NASA Astrophysics Data System (ADS)

    Rubin, A. M.; Ampuero, J.

    2007-12-01

    Combined seismic and geodetic data from subduction zones and the Salton Trough have revealed slow slip events with reasonably well-defined propagation speeds. This in turn is suggestive of a more-or-less well- defined front separating nearly locked regions outside the slipping zone from interior regions that slide much more rapidly. Such crack-like nucleation fronts arise naturally in models of rate-and-state friction for lab-like values of a/b, where a and b are the coefficients of the velocity- and state-dependence of the frictional strength (with the surface being velocity-neutral for a/b=1). If the propagating front has a quasi-steady shape, the propagation and slip speeds are kinematically tied via the local slip gradient. Given a sufficiently sharp front, the slip gradient is given dimensionally by Δτp- r/μ', where Δτp-r is the peak-to-residual stress drop at the front and μ' the effective elastic shear modulus. Rate-and-state simulations indicate that Δτp-r is given reasonably accurately by bσ\\ln(Vmaxθi/Dc), where σ is the effective normal stress, Vmax is the maximum slip speed behind the propagating front, θi is the the value of "state" ahead of the propagating front, and Dc is the characteristic slip distance for state evolution. Except for a coefficient of order unity, Δτp-r is independent of the evolution law. This leads to Vprop/Vmax ~μ'/[bσ\\ln(Vmaxθi/Dc)]. For slip speeds a few orders of magnitude above background, \\ln(Vmaxθi/Dc) can with reasonable accuracy be assigned some representative value (~4-5, for example). Subduction zone transients propagate on the order of 10 km/day or 10-1 m/s. Geodetic data constrain the average slip speed to be a few times smaller than 1 cm/day or 10-7 m/s. However, numerical models indicate that the maximum slip speed at the front may be several times larger than the average, over a length scale that is probably too small to resolve geodetically, so a representative value of Vprop/Vmax may be ~106

  10. Hydrodynamic slip in silicon nanochannels

    NASA Astrophysics Data System (ADS)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-03-01

    Equilibrium and nonequilibrium molecular dynamics simulations were performed to better understand the hydrodynamic behavior of water flowing through silicon nanochannels. The water-silicon interaction potential was calibrated by means of size-independent molecular dynamics simulations of silicon wettability. The wettability of silicon was found to be dependent on the strength of the water-silicon interaction and the structure of the underlying surface. As a result, the anisotropy was found to be an important factor in the wettability of these types of crystalline solids. Using this premise as a fundamental starting point, the hydrodynamic slip in nanoconfined water was characterized using both equilibrium and nonequilibrium calculations of the slip length under low shear rate operating conditions. As was the case for the wettability analysis, the hydrodynamic slip was found to be dependent on the wetted solid surface atomic structure. Additionally, the interfacial water liquid structure was the most significant parameter to describe the hydrodynamic boundary condition. The calibration of the water-silicon interaction potential performed by matching the experimental contact angle of silicon led to the verification of the no-slip condition, experimentally reported for silicon nanochannels at low shear rates.

  11. Frictional melt and seismic slip

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; di Toro, G.; Hirose, T.; Shimamoto, T.

    2008-01-01

    Frictional melt is implied in a variety of processes such as seismic slip, ice skating, and meteorite combustion. A steady state can be reached when melt is continuously produced and extruded from the sliding interface, as shown recently in a number of laboratory rock friction experiments. A thin, low-viscosity, high-temperature melt layer is formed resulting in low shear resistance. A theoretical solution describing the coupling of shear heating, thermal diffusion, and extrusion is obtained, without imposing a priori the melt thickness. The steady state shear traction can be approximated at high slip rates by the theoretical form τss = σn1/4 (A/?) ? under a normal stress σn, slip rate V, radius of contact area R (A is a dimensional normalizing factor and W is a characteristic rate). Although the model offers a rather simplified view of a complex process, the predictions are compatible with experimental observations. In particular, we consider laboratory simulations of seismic slip on earthquake faults. A series of high-velocity rotary shear experiments on rocks, performed for σn in the range 1-20 MPa and slip rates in the range 0.5-2 m s-1, is confronted to the theoretical model. The behavior is reasonably well reproduced, though the effect of radiation loss taking place in the experiment somewhat alters the data. The scaling of friction with σn, R, and V in the presence of melt suggests that extrapolation of laboratory measures to real Earth is a highly nonlinear, nontrivial exercise.

  12. Slip rate and tremor genesis in Cascadia

    NASA Astrophysics Data System (ADS)

    Wech, Aaron G.; Bartlow, Noel M.

    2014-01-01

    At 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.

  13. Liquid slip on a nanostructured surface.

    PubMed

    Lee, Doo Jin; Cho, Ki Yeon; Jang, Soohwan; Song, Young Seok; Youn, Jae Ryoun

    2012-07-17

    We explored a liquid slip, referred to as the Navier slip, at liquid-solid interface. Such a slip is provoked by the physicochemical features of the liquid-solid system. The goal of this study was to investigate the effect of a nanoengineered surface structure on liquid slip by fabricating the self-assembly structure of nano Zinc oxide (n-ZnO). We have also examined how the liquid-solid surface interaction controlled by hydrophobic chemical treatment affects the liquid slip. The findings showed that liquid slip increases with decreasing the characteristic length scales (e.g., channel height and depth), resulting in drag reduction. It was also found that dewetted (Cassie) state due to the generation of air gap developed by n-ZnO was more critical for the liquid slip than the minimization of interface interaction. The linear and nonlinear Navier slip models showed that liquid slip behavior is more obvious when increasing the nonlinearity. This study will contribute to understanding of the underlying physics behind fluid slip phenomena, such as the Navier slip for Newtonian liquids and Maxwell's slip for Newtonian gases. PMID:22717057

  14. Optical rotary joint

    NASA Astrophysics Data System (ADS)

    May, R. G., Jr.

    1982-06-01

    The primary objective of this contract is the design, fabrication, and testing of an optical rotary joint which permits transmission of signals through optical fibers across the interface of two environments rotating relative to each other. Outstanding optical performance is achieved through the use of gradient index lenses to couple radiation across the separation between two fibers. The salient features of this device are bidirectional operation at two wavelengths (850 nm and 1300 nm), low insertion loss, low rotationally induced variation of attenuation, a seven-circuit electrical slip-ring assembly, and rugged construction. The device is designed to facilitate the application of future designs to pressurized, subsea environments.

  15. Accessory slips of the extensor digiti minimi.

    PubMed

    Li, Jing; Mao, Qing Hua

    2014-01-01

    During the educational dissection of a 69-year-old Chinese male cadaver, an extensor digiti minimi (EDM) with five slips on the right hand was discovered. Except for the two slips of the little finger, the two radial slips were inserted into the dorsal aponeurosis of the middle finger and the ring finger, respectively. The middle slip was connected to the junctura tendinum in the fourth intermetacarpal spaces. Variations in this region are of paramount importance for the reconstructive surgeons, who may utilize the accessory slips to restore functional capacity of the fingers. PMID:24970007

  16. Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data

    USGS Publications Warehouse

    Johanson, I.A.; Fielding, E.J.; Rolandone, F.; Burgmann, R.

    2006-01-01

    We invert interferometric synthetic aperture radar (InSAR) data jointly with campaign and continuous global positioning system (GPS) data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The InSAR dataset consists of eight interferograms from data collected by the Envisat and Radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period. The two datasets complement each other, with the InSAR providing dense sampling of motion in the range direction of the satellite and the GPS providing more sparse, but three-dimensional measurements of ground motion. The model assumes exponential decay of the postseismic slip with a decay time constant of 0.087 years, determined from time series modeling of continuous GPS and creepmeter data. We find a geodetic moment magnitude of M 6.2 for a 1-day coseismic model and Mw 6.1 for the entire postseismic period. The coseismic rupture occurred mainly in two slip asperities; one near the hypocenter and the other 15-20 km north. Postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two M 5.0 aftershocks. A comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the Parkfield earthquake is as little as 25% of the total. This underlines the importance of aseismic slip in the slip budget for the Parkfield segment.

  17. Flow-induced vibrations-1987

    SciTech Connect

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

    1987-01-01

    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.

  18. Spatial slip behavior of large strike-slip fault belts: Implications for the Holocene slip rates of the eastern termination of the North Anatolian Fault, Turkey

    NASA Astrophysics Data System (ADS)

    Zabcı, Cengiz; Sançar, Taylan; Akyüz, H. Serdar; Kıyak, Nafiye Güneç

    2015-12-01

    We present new data on Holocene slip rates for the eastern end of the North Anatolian Fault (NAF) by using the optically stimulated luminescence ages of the offset terrace deposits at two sites, where a total of four displaced landforms was studied. Each offset feature was analyzed independently, and three different assumptions were made for all the offsets, depending on whether the age of the upper tread (upper tread reconstruction), the lower tread (lower tread reconstruction), or all bounding surfaces (intermediate solution) were used in dating of the terrace risers. The deflected geometry of the risers strongly suggests the use of either the intermediate solution or the upper tread reconstruction. The joint slip rate distributions for the upper tread reconstructions and the intermediate solutions were modeled as 13.0 + 1.8 / -1.4 and 14.3 + 5.8 / -2.4 mm/yr (2σ), respectively. Although the intermediate solution covers the full range of ages for the measured displacements, the curved geometry of the terrace risers suggests that the initiations of the riser offsets are most probably close to the abandonment ages of the upper terrace treads. Therefore, we accepted the joint slip rate of the intermediate solution but suggested that the average rate for the main displacement zone of the eastern NAF should be close to its lower limits. This slower rate with respect to previous estimates suggests that the total deformation is not only accommodated on the main displacement zone but is also distributed along the secondary faults to the south of the easternmost segments of the NAF.

  19. Molecular scale simulation of homopolymer wall slip.

    PubMed

    Dorgan, John R; Rorrer, Nicholas A

    2013-04-26

    The first molecular scale simulation of highly entangled polydisperse homopolymers that is capable of capturing all three regions--no slip, weak slip, and strong slip--of the hydrodynamic boundary condition is presented. An on-lattice dynamic Monte Carlo technique capable of correctly capturing both unentangled and entangled polymer dynamics is used to study the molecular details of wall slip phenomena for homopolymers and energetically neutral walls. For unentangled chains (those exhibiting Rouse dynamics) weak slip is not present but evidence of strong slip is manifest at very high shear rates. For entangled chains (of sufficient length to exhibit reptation dynamics), both weak and strong slip are observed. Consistent with numerous experimental studies, disentanglement and cohesive failure occur at high shear rates. Disentanglement is clearly evidenced in a nonlinear velocity profile that exhibits shear banding, in an excess of chain ends at the slip plane, and perhaps most importantly in a nonmonotonic stress versus shear rate response. The chain end density exhibits a pretransitional periodicity prior to disentanglement. Unentangled Rouse chains do not show this pretransitional response or a bifurcation in their stress versus shear rate response. Finally, it is shown that when polydispersity is introduced, slip phenomena are severely reduced and the inherent constitutive bifurcation is limited to a small region. Predictions are in post facto agreement with many experiments, are distinct from existing results obtained using molecular dynamics simulation techniques, and shed light on fundamental mechanisms of polymer wall slip. PMID:23679746

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Fault surface roughness is a principal factor influencing fault and earthquake mechanics. However, little is known on roughness of fault surfaces at seismogenic depths, and particularly on how it evolves with accumulating slip. We have studied seismogenic fault surfaces of the Gole Larghe Fault Zone, which exploit precursor cooling joints of the Adamello tonalitic pluton (Italian Alps). These faults developed at 9-11 km and 250-300°C. Seismic slip along these surfaces, which individually accommodated from 1 to 20 m of net slip, resulted in the production of cm-thick cataclasites and pseudotachylytes (solidified melts produced during seismic slip). The roughness of fault surfaces was determined with a multi-resolution aerial and terrestrial LIDAR and photogrammetric dataset (Bistacchi et al., 2011, Pageoph, doi: 10.1007/s00024-011-0301-7). Fault surface roughness is self-affine, with Hurst exponent H < 1, indicating that faults are comparatively smoother at larger wavelengths. Fault surface roughness is inferred to have been inherited from the precursor cooling joints, which show H ≈ 0.8. Slip on faults progressively modified the roughness distribution, lowering the Hurst exponent in the along-slip direction up to H ≈ 0.6. This behaviour has been observed for wavelengths up to the scale of the accumulated slip along each individual fault surface, whilst at larger wavelengths the original roughness seems not to be affected by slip. Processes that contribute to modify fault roughness with slip include brittle failure of the interacting asperities (production of cataclasites) and frictional melting (production of pseudotachylytes). To quantify the "wear" due to these processes, we measured, together with the roughness of fault traces and their net slip, the thickness and distribution of cataclasites and pseudotachylytes. As proposed also in the tribological literature, we observe that wearing is scale dependent, as smaller wavelength asperities have a shorter

  1. Process for slip casting textured tubular structures

    DOEpatents

    Steinlage, Greg A.; Trumble, Kevin P.; Bowman, Keith J.

    2002-01-01

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

  2. Multicycle slip distribution along a laboratory fault

    USGS Publications Warehouse

    Chi-Yu, King

    1991-01-01

    Slip distribution along a laboratory fault, which consists of eight spring-connected blocks that are elastically driven to slide on a frictional surface, has been examined for a "long' sequence of slip events to test the applicability of some conceptual models. The distributions of large slip events are found to be quite variable and do not fit the uniform slip or characteristic earthquake models. The rupture initiation points are usually not near the corresponding maximum slip points, in contrast to observations by Thatcher (1990) and by Fukao and Kikuchi (1987) that earthquake hypocenters are commonly near corresponding regions of maximum slip in the fault planes. The results suggest that earthquake prediction monitoring efforts should not be limited to a small region near an asperity but should be spread out to cover the entire fault segment in a seismic gap in order to detect the condition of simultaneous strain buildup. -from Author

  3. Learning to predict slip for ground robots

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  4. Fault slip distribution and fault roughness

    NASA Astrophysics Data System (ADS)

    Candela, Thibault; Renard, François; Schmittbuhl, Jean; Bouchon, Michel; Brodsky, Emily E.

    2011-11-01

    We present analysis of the spatial correlations of seismological slip maps and fault topography roughness, illuminating their identical self-affine exponent. Though the complexity of the coseismic spatial slip distribution can be intuitively associated with geometrical or stress heterogeneities along the fault surface, this has never been demonstrated. Based on new measurements of fault surface topography and on statistical analyses of kinematic inversions of slip maps, we propose a model, which quantitatively characterizes the link between slip distribution and fault surface roughness. Our approach can be divided into two complementary steps: (i) Using a numerical computation, we estimate the influence of fault roughness on the frictional strength (pre-stress). We model a fault as a rough interface where elastic asperities are squeezed. The Hurst exponent ?, characterizing the self-affinity of the frictional strength field, approaches ?, where ? is the roughness exponent of the fault surface in the direction of slip. (ii) Using a quasi-static model of fault propagation, which includes the effect of long-range elastic interactions and spatial correlations in the frictional strength, the spatial slip correlation is observed to scale as ?, where ? represents the Hurst exponent of the slip distribution. Under the assumption that the origin of the spatial fluctuations in frictional strength along faults is the elastic squeeze of fault asperities, we show that self-affine geometrical properties of fault surface roughness control slip correlations and that ?. Given that ? for a wide range of faults (various accumulated displacement, host rock and slip movement), we predict that ?. Even if our quasi-static fault model is more relevant for creeping faults, the spatial slip correlations observed are consistent with those of seismological slip maps. A consequence is that the self-affinity property of slip roughness may be explained by fault geometry without considering

  5. The slipping rib syndrome: A case report

    PubMed Central

    van Delft, E.A.K.; van Pul, K.M.; Bloemers, F.W.

    2016-01-01

    We present a case report and review of literature about slipping rib syndrome, a syndrome rarely recognized and often un or misdiagnosed. In literature there is no clear consensus about the diagnosis and treatment. We present a case of a 47 year old man who was diagnosed with slipping rib syndrome after a cycling incident 8 years ago. Also, we developed a flow chart according the diagnostic and therapeutic steps in the treatment of slipping rib syndrome. Central massage Knowledge and treatment of the slipping rib syndrome can prevent chronic complaints and unnecessary comprehensive treatment. PMID:27082995

  6. Molecular Scale Simulation of Homopolymer Wall Slip

    NASA Astrophysics Data System (ADS)

    Dorgan, John R.; Rorrer, Nicholas A.

    2013-04-01

    The first molecular scale simulation of highly entangled polydisperse homopolymers that is capable of capturing all three regions—no slip, weak slip, and strong slip—of the hydrodynamic boundary condition is presented. An on-lattice dynamic Monte Carlo technique capable of correctly capturing both unentangled and entangled polymer dynamics is used to study the molecular details of wall slip phenomena for homopolymers and energetically neutral walls. For unentangled chains (those exhibiting Rouse dynamics) weak slip is not present but evidence of strong slip is manifest at very high shear rates. For entangled chains (of sufficient length to exhibit reptation dynamics), both weak and strong slip are observed. Consistent with numerous experimental studies, disentanglement and cohesive failure occur at high shear rates. Disentanglement is clearly evidenced in a nonlinear velocity profile that exhibits shear banding, in an excess of chain ends at the slip plane, and perhaps most importantly in a nonmonotonic stress versus shear rate response. The chain end density exhibits a pretransitional periodicity prior to disentanglement. Unentangled Rouse chains do not show this pretransitional response or a bifurcation in their stress versus shear rate response. Finally, it is shown that when polydispersity is introduced, slip phenomena are severely reduced and the inherent constitutive bifurcation is limited to a small region. Predictions are in post facto agreement with many experiments, are distinct from existing results obtained using molecular dynamics simulation techniques, and shed light on fundamental mechanisms of polymer wall slip.

  7. Longitudinal wheel slip during ABS braking

    NASA Astrophysics Data System (ADS)

    Hartikainen, Lassi; Petry, Frank; Westermann, Stephan

    2015-02-01

    Anti-lock braking system (ABS) braking tests with two subcompact passenger cars were performed on dry and wet asphalt, as well as on snow and ice surfaces. The operating conditions of the tyres in terms of wheel slip were evaluated using histograms of the wheel slip data. The results showed different average slip levels for different road surfaces. It was also found that changes in the tyre tread stiffness affected the slip operating range through a modification of the slip value at which the maximum longitudinal force is achieved. Variation of the tyre footprint length through modifications in the inflation pressure affected the slip operating range as well. Differences in the slip distribution between vehicles with different brake controllers were also observed. The changes in slip operating range in turn modified the relative local sliding speeds between the tyre and the road. The results highlight the importance of the ABS controller's ability to adapt to changing slip-force characteristics of tyres and provide estimates of the magnitude of the effects of different tyre and road operating conditions.

  8. Observation of slip flow in thermophoresis.

    PubMed

    Weinert, Franz M; Braun, Dieter

    2008-10-17

    Two differing theories aim to describe fluidic thermophoresis, the movement of particles along a temperature gradient. While thermodynamic approaches rely on local equilibrium, hydrodynamic descriptions assume a quasi-slip-flow boundary condition at the particle's surface. Evidence for slip flow is presented for the case of thermal gradients exceeding (aS_(T)(-1) with particle radius a and Soret coefficient S_(T). Thermophoretic slip flow at spheres near a surface attracts or repels tracer particles perpendicular to the thermal gradient. Moreover, particles mutually attract and form colloidal crystals. Fluid dynamic slip explains the latter quantitatively. PMID:18999718

  9. Development of a liquid metal slip ring

    NASA Technical Reports Server (NTRS)

    Weinberger, S. M.

    1972-01-01

    A liquid metal slip ring/solar orientation mechanism was designed and a model tested. This was a follow-up of previous efforts for the development of a gallium liquid metal slip ring in which the major problem was the formation and ejection of debris. A number of slip ring design approaches were studied. The probe design concept was fully implemented with detail drawings and a model was successfully tested for dielectric strength, shock vibration, acceleration and operation. The conclusions are that a gallium liquid metal slip ring/solar orientation mechanism is feasible and that the problem of debris formation and ejection has been successfully solved.

  10. Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

    PubMed

    Wetzel, Christoph; Windhövel, Ulrich; Mewes, Detlef; Ceylan, Orhan

    2015-01-01

    Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field. PMID:26414511

  11. Analysis of minor fractures associated with joints and faulted joints

    NASA Astrophysics Data System (ADS)

    Cruikshank, Kenneth M.; Zhao, Guozhu; Johnson, Arvid M.

    In this paper, we use fracture mechanics to interpret conditions responsible for secondary cracks that adorn joints and faulted joints in the Entrada Sandstone in Arches National Park, U.S.A. Because the joints in most places accommodated shearing offsets of a few mm to perhaps 1 dm, and thus became faulted joints, some of the minor cracks are due to faulting. However, in a few places where the shearing was zero, one can examine minor cracks due solely to interaction of joint segments at the time they formed. We recognize several types of minor cracks associated with subsequent faulting of the joints. One is the kink, a crack that occurs at the termination of a straight joint and whose trend is abruptly different from that of the joint. Kinks are common and should be studied because they contain a great deal of information about conditions during fracturing. The sense of kinking indicates the sense of shear during faulting: a kink that turns clockwise with respect to the direction of the main joint is a result of right-lateral shear, and a kink that turns counterclockwise is a result of left-lateral shear. Furthermore, the kink angle is related to the ratio of the shear stress responsible for the kinking to the normal stress responsible for the opening of the joint. The amount of opening of a joint at the time it faulted or even at the time the joint itself formed can be estimated by measuring the kink angle and the amount of strike-slip at some point along the faulted joint. Other fractures that form near terminations of pre-existing joints in response to shearing along the joint are horsetail fractures. Similar short fractures can occur anywhere along the length of the joints. The primary value in recognizing these fractures is that they indicate the sense of faulting accommodated by the host fracture and the direction of maximum tension. Even where there has been insignificant regional shearing in the Garden Area, the joints can have ornate terminations. Perhaps

  12. Slip segmentation and slow rupture to the trench during the 2015, Mw8.3 Illapel, Chile earthquake

    NASA Astrophysics Data System (ADS)

    Melgar, Diego; Fan, Wenyuan; Riquelme, Sebastian; Geng, Jianghui; Liang, Cunren; Fuentes, Mauricio; Vargas, Gabriel; Allen, Richard M.; Shearer, Peter M.; Fielding, Eric J.

    2016-02-01

    The 2015 Mw8.3 Illapel, Chile earthquake is the latest megathrust event on the central segment of that subduction zone. It generated strong ground motions and a large (up to 11 m runup) tsunami which prompted the evacuation of more than 1 million people in the first hours following the event. Observations during recent earthquakes suggest that these phenomena can be associated with rupture on different parts of the megathrust. The deep portion generates strong shaking while slow, large slip on the shallow fault is responsible for the tsunami. It is unclear whether all megathrusts can have shallow slip during coseismic rupture and what physical properties regulate this. Here we show that the Illapel event ruptured both deep and shallow segments with substantial slip. We resolve a kinematic slip model using regional geophysical observations and analyze it jointly with teleseismic backprojection. We find that the shallow and deep portions of the megathrust are segmented and have fundamentally different behavior. We forward calculate local tsunami propagation from the resolved slip and find good agreement with field measurements, independently validating the slip model. These results show that the central portion of the Chilean subduction zone has accumulated a significant shallow slip deficit and indicates that, given enough time, shallow slip might be possible everywhere along the subduction zone.

  13. Environmental study of miniature slip rings

    NASA Technical Reports Server (NTRS)

    Radnik, J. L.

    1967-01-01

    Investigation studied the long term operation of miniature slip ring assembles in high vacuum of space and included the influence of ring, brush, and insulator materials on electrical noise and mechanical wear. Results show that soft metal vapor plating and niobium diselenide miniature slip rings are beneficial.

  14. Unified slip boundary condition for fluid flows.

    PubMed

    Thalakkottor, Joseph John; Mohseni, Kamran

    2016-08-01

    Determining the correct matching boundary condition is fundamental to our understanding of several everyday problems. Despite over a century of scientific work, existing velocity boundary conditions are unable to consistently explain and capture the complete physics associated with certain common but complex problems, such as moving contact lines and corner flows. The widely used Maxwell and Navier slip boundary conditions make an implicit assumption that velocity varies only in the wall normal direction. This makes their boundary condition inapplicable in the vicinity of contact lines and corner points, where velocity gradient exists both in the wall normal and wall tangential directions. In this paper, by identifying this implicit assumption we are able to extend Maxwell's slip model. Here, we present a generalized velocity boundary condition that shows that slip velocity is a function of not only the shear rate but also the linear strain rate. In addition, we present a universal relation for slip length, which shows that, for a general flow, slip length is a function of the principal strain rate. The universal relation for slip length along with the generalized velocity boundary condition provides a unified slip boundary condition to model a wide range of steady Newtonian fluid flows. We validate the unified slip boundary for simple Newtonian liquids by using molecular dynamics simulations and studying both the moving contact line and corner flow problems. PMID:27627398

  15. Episodic tremor and slip on the Cascadia subduction zone: the chatter of silent slip.

    PubMed

    Rogers, Garry; Dragert, Herb

    2003-06-20

    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 activity is minor or nonexistent. We call this associated tremor and slip phenomenon episodic tremor and slip (ETS) and propose that ETS activity can be used as a real-time indicator of stress loading of the Cascadia megathrust earthquake zone. PMID:12738870

  16. [Evaporating Droplet and Imaging Slip Flows

    NASA Technical Reports Server (NTRS)

    Larson, R. G.

    2002-01-01

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

  17. The role of water in slip casting

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  18. Slow slip generated by dehydration reaction coupled with slip-induced dilatancy and thermal pressurization

    NASA Astrophysics Data System (ADS)

    Yamashita, Teruo; Schubnel, Alexandre

    2016-05-01

    Sustained slow slip, which is a distinctive feature of slow slip events (SSEs), is investigated theoretically, assuming a fault embedded within a fluid-saturated 1D thermo-poro-elastic medium. The object of study is specifically SSEs occurring at the down-dip edge of seismogenic zone in hot subduction zones, where mineral dehydrations (antigorite, lawsonite, chlorite, and glaucophane) are expected to occur near locations where deep slow slip events are observed. In the modeling, we introduce dehydration reactions, coupled with slip-induced dilatancy and thermal pressurization, and slip evolution is assumed to interact with fluid pressure change through Coulomb's frictional stress. Our calculations show that sustained slow slip events occur when the dehydration reaction is coupled with slip-induced dilatancy. Specifically, slow slip is favored by a low initial stress drop, an initial temperature of the medium close to that of the dehydration reaction equilibrium temperature, a low permeability, and overall negative volume change associated with the reaction (i.e., void space created by the reaction larger than the space occupied by the fluid released). Importantly, if we do not assume slip-induced dilatancy, slip is accelerated with time soon after the slip onset even if the dehydration reaction is assumed. This suggests that slow slip is sustained for a long time at hot subduction zones because dehydration reaction is coupled with slip-induced dilatancy. Such slip-induced dilatancy may occur at the down-dip edge of seismogenic zone at hot subduction zones because of repetitive occurrence of dehydration reaction there.

  19. Hypermobile joints

    MedlinePlus

    ... too far. In children with hypermobility syndrome, those ligaments are loose or weak. This may lead to: Arthritis, which may develop over time Dislocated joints, which is a separation of two bones where they meet at a joint Sprains and strains Children with hypermobile joints also often have flat ...

  20. Joint Disorders

    MedlinePlus

    A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

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

    USGS Publications Warehouse

    McGarr, A.; Fletcher, Joe B.

    2003-01-01

    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.

  2. Effects of joint on dynamics of space deployable structure

    NASA Astrophysics Data System (ADS)

    Guo, Hongwei; Zhang, Jing; Liu, Rongqiang; Deng, Zongquan

    2013-09-01

    Joints are necessary components in large space deployable truss structures which have significant effects on dynamic behavior of these joint dominated structures. Previous researches usually analyzed effects of one or fewer joint characters on dynamics of jointed structures. Effects of joint stiffness, damping, location, number, clearance and contact stiffness on dynamics of jointed structures are systematically analyzed. Cantilever beam model containing linear joints is developed based on finite element method, influence of joint on natural frequencies and mode shapes of the jointed system are analyzed. Analytical results show that frequencies of jointed system decrease dramatically when peak mode shapes occur at joint locations, and there are cusp shapes present in mode shapes. System frequencies increase with joint damping increasing, there are different joint damping to achieve maximum system damping for different joint stiffness. Joint nonlinear force-displacement is described by describing function method, one-DOF model containing nonlinear joints is established to analyze joints freeplay and hysteresis nonlinearities. Analysis results show that nonlinear effects of freeplay and hysteresis make dynamic responses switch from one resonance frequency to another frequency when amplitude exceed demarcation values. Joint contact stiffness determine degree of system nonlinearity, while exciting force level, clearance and slipping force affect amplitude of dynamic response. Dynamic responses of joint dominated deployable truss structure under different sinusoidal exciting force levels are tested. The test results show obvious nonlinear behaviors contributed by joints, dynamic response shifts to lower frequency and higher amplitude as exciting force increasing. The test results are further compared with analytical results, and joint nonlinearity tested is coincident with hysteresis nonlinearity. Analysis method of joint effects on dynamic characteristics of jointed

  3. Tsunami Hazards From Strike-Slip Earthquakes

    NASA Astrophysics Data System (ADS)

    Legg, M. R.; Borrero, J. C.; Synolakis, C. E.

    2003-12-01

    Strike-slip faulting is often considered unfavorable for tsunami generation during large earthquakes. Although large strike-slip earthquakes triggering landslides and then generating substantial tsunamis are now recognized hazards, many continue to ignore the threat from submarine tectonic displacement during strike-slip earthquakes. Historical data record the occurrence of tsunamis from strike-slip earthquakes, for example, 1906 San Francisco, California, 1994 Mindoro, Philippines, and 1999 Izmit, Turkey. Recognizing that strike-slip fault zones are often curved and comprise numerous en echelon step-overs, we model tsunami generation from realistic strike-slip faulting scenarios. We find that tectonic seafloor uplift, at a restraining bend or"pop-up" structure, provides an efficient mechanism to generate destructive local tsunamis; likewise for subsidence at divergent pull-apart basin structures. Large earthquakes on complex strike-slip fault systems may involve both types of structures. The California Continental Borderland is a high-relief submarine part of the active Pacific-North America transform plate boundary. Natural harbors and bays created by long term vertical motion associated with strike-slip structural irregularities are now sites of burgeoning population and major coastal infrastructure. Significant local tsunamis generated by large strike-slip earthquakes pose a serious, and previously unrecognized threat. We model several restraining bend pop-up structures offshore southern California to quantify the local tsunami hazard. Maximum runup derived in our scenarios ranges from one to several meters, similar to runup observed from the 1994 Mindoro, Philippines, (M=7.1) earthquake. The runup pattern is highly variable, with local extremes along the coast. We only model the static displacement field for the strike-slip earthquake source; dynamic effects of moving large island or submerged banks laterally during strike-slip events remains to be examined

  4. Electrostatic precursors to granular slip events

    PubMed Central

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

    2012-01-01

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

  5. Dynamical Stability of Slip-stacking Particles

    SciTech Connect

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-04

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

  6. Friction of water slipping in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Ming D.; Shen, Luming; Sheridan, John; Liu, Jefferson Zhe; Chen, Chao; Zheng, Quanshui

    2011-03-01

    Liquid slip is essential in nanofluidic systems, as shrinking channel size leads to a dramatic increase in flow resistance and thus high-energy consumption for driving nonslip flow. Using large-scale nonequilibrium molecular dynamics simulation of water flowing in carbon nanotubes (CNT’s), we show that the relationship between the CNT wall-water interfacial friction stress and slip velocity follows a transition-state-theory-based inverse hyperbolic sine function, which remains universally valid regardless of wetting properties, CNT chiralities, and CNT sizes, and holds for all slip velocities from 0 to 1400 m/s. The finding could benefit the research in desalination and other chemical purification techniques.

  7. Slip mechanisms in complex fluid flows.

    PubMed

    Hatzikiriakos, Savvas G

    2015-10-28

    The classical no-slip boundary condition of fluid mechanics is not always a valid assumption for the flow of several classes of complex fluids including polymer melts, their blends, polymer solutions, microgels, glasses, suspensions and pastes. In fact, it appears that slip effect in these systems is the rule and not the exemption. The occurrence of slip complicates the analysis of rheological data, although it provides new opportunities to understand their behavior in restricted environments delineating additional molecular mechanisms i.e. entropic restrictions due to limitations in the number of molecular conformations. This article discusses these complexities and provides future research opportunities. PMID:26345121

  8. Dynamical stability of slip-stacking particles

    NASA Astrophysics Data System (ADS)

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-01

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

  9. Multiparameter investigation of gravitational slip

    SciTech Connect

    Daniel, Scott F.; Caldwell, Robert R.; Cooray, Asantha; Serra, Paolo; Melchiorri, Alessandro

    2009-07-15

    A detailed analysis of gravitational slip, a new post-general relativity cosmological parameter characterizing the degree of departure of the laws of gravitation from general relativity on cosmological scales, is presented. This phenomenological approach assumes that cosmic acceleration is due to new gravitational effects; the amount of spacetime curvature produced per unit mass is changed in such a way that a universe containing only matter and radiation begins to accelerate as if under the influence of a cosmological constant. Changes in the law of gravitation are further manifest in the behavior of the inhomogeneous gravitational field, as reflected in the cosmic microwave background, weak lensing, and evolution of large-scale structure. The new parameter {pi}{sub 0} is naively expected to be of order unity. However, a multiparameter analysis, allowing for variation of all of the standard cosmological parameters, finds that {pi}{sub 0}=0.09{sub -0.59}{sup +0.74}(2{sigma}), where {pi}{sub 0}=0 corresponds to a cosmological constant plus cold dark matter universe under general relativity. Future probes of the cosmic microwave background (Planck) and large-scale structure (Euclid) may improve the limits by a factor of 4.

  10. Is slow slip in Cascadia tidally modulated?

    NASA Astrophysics Data System (ADS)

    Hawthorne, J. C.; Rubin, A. M.

    2009-12-01

    Several studies have shown that the seismic tremor in episodic tremor and slip is tidally modulated, suggesting a strong sensitivity to the rather small tidal stresses. We address whether the slip is also tidally modulated by examining data from six borehole strainmeters in northwest Washington and southern Vancouver Island. We use the processed data provided by Plate Boundary Observatory (PBO), which is resampled to 5-minute intervals. However, we recompute empirical corrections for tides, a long-term linear trend, and barometric pressure in the 50 days surrounding each slow slip event. We then fit sinusoids at the tidal periods to the processed data as proxies for the tidally modulated component of slip, along with a linear trend as a proxy for the net strain in the slow slip. The data are too noisy to allow detection any tidal modulation using only a single event and station. We therefore simultaneously fit data from multiple stations and from three slow slip events since 2007. This assumes that the phase of the tides at the slipping regions detected by all stations is the same and that the phase of the fault response to the tidal stress is constant. Combining the stations and events both reduces the noise at the tidal periods and creates a longer time series, which allows us to separate energy at the different tidal frequencies. We find significant tidal signals at the 12.4 and 25.8-hour periods which differ from zero at the 1.5 to 2-sigma level. Errors are estimated by bootstrapping the slow slip strain and by considering the tidal signal at times before the slow slip event. The 12.4 and 25.8-hour sinusoids have amplitudes of 23 (10-40 at 2-sigma) and 15 (0-30 at 2-sigma) percent of the maximum amplitude that does not allow the slow slip strain signal to change sign, where the mean strain rate is estimated from the linear trends fit to the slow slip data. In terms of slip rate, the sinusoids at each period could then modulate the slip rate 23 and 15 percent

  11. Slip compensation at fault damage zones along earthquake surface ruptures

    NASA Astrophysics Data System (ADS)

    Choi, J.; Kim, Y.

    2013-12-01

    Surface ruptures associated with earthquake faulting commonly comprise a number of segments, and the discontinuities form tip and linking damage zones, which are deformed regions consisting of secondary features. Stress transferring or releasing, when seismic waves pass through the discontinuities, could produce different slip features depending on rupture propagation or termination. Thus, slip patterns at fault damage zones can be one of the key factors to understand fault kinematics, fault evolution and, hence, earthquake hazard. In some previous studies (e.g. Peacock and Sanderson, 1991; Kim and Sanderson, 2005), slip distribution along faults to understand the connectivity or maturity of segmented faults system have commonly been analyzed based on only the main slip components (dip-slip or strike-slip). Secondary slip components, however, are sometimes dominant at fault damage zones, such as linkage and tip zones. In this study, therefore, we examine slip changes between both main and secondary slip components along unilaterally propagated coseismic strike-slip ruptures. Horizontal and vertical components of slip and the slip compensation patterns at tip and linking damage zones are various from slip deficit (decrease in both slip components) through slip compensation (increase of vertical slip with horizontal slip decrease) to slip neutral. Front and back tip zones, which are classified depending on main propagation direction of earthquake ruptures, show different slip patterns; slip compensation is observed at the frontal tip whilst slip deficit occurs at the back tip zone. Average values of the two slip components and their compensative patterns at linking damage zones are closely related with the ratio of length to width (L/W) of linkage geometry; the horizontal slip is proportional to the ratio of L/W, whilst the vertical slip shows little dependence on the value L/W. When the L/W is greater than ~2, average values of two slip components are almost similar

  12. Action slips during whole-body vibration.

    PubMed

    Ishimatsu, Kazuma; Meland, Anders; Hansen, Tor Are S; Kåsin, Jan Ivar; Wagstaff, Anthony S

    2016-07-01

    Helicopter aircrew members engage in highly demanding cognitive tasks in an environment subject to whole-body vibration (WBV). Sometimes their actions may not be according to plan (e.g. action slips and lapses). This study used a Sustained Attention to Response Task (SART) to examine whether action slips were more frequent during exposure to WBV. Nineteen participants performed the SART in two blocks. In the WBV block participants were exposed to 17 Hz vertical WBV, which is typical of larger helicopter working environments. In the No-WBV block there was no WBV. There were more responses to the rare no-go digit 3 (i.e. action slips) in the WBV block, and participants responded faster in the WBV block. These results suggest that WBV influences response inhibition, and can induce impulsive responding. WBV may increase the likelihood of action slips, mainly due to failure of response inhibition. PMID:26611989

  13. Slip-mediated dewetting of polymer microdroplets.

    PubMed

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

    2016-02-01

    Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. PMID:26787903

  14. Bone scintigraphy in slipped capital femoral epiphysis

    SciTech Connect

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

    1983-12-01

    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.

  15. Slip boundary conditions over curved surfaces.

    PubMed

    Guo, Lin; Chen, Shiyi; Robbins, Mark O

    2016-01-01

    Molecular dynamics simulations are used to investigate the influence of surface curvature on the slip boundary condition for a simple fluid. The slip length is measured for flows in planar and cylindrical geometries with a range of wall-fluid interactions. As wall curvature increases, the slip length decreases dramatically for closely packed surfaces and increases for sparse ones. The magnitude of the changes depends on the crystallographic orientation and differs for flow along and perpendicular to the direction of curvature. These different patterns of behavior are related to the curvature-induced variation in the ratio of the spacing between fluid atoms to the spacing between minima in the potential from the solid surface. The results are consistent with a microscopic theory for the viscous friction between fluid and wall that expresses the slip length in terms of the lateral response of the fluid to the wall potential and the characteristic decay time of this response. PMID:26871153

  16. Slip boundary conditions over curved surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Lin; Chen, Shiyi; Robbins, Mark O.

    2016-01-01

    Molecular dynamics simulations are used to investigate the influence of surface curvature on the slip boundary condition for a simple fluid. The slip length is measured for flows in planar and cylindrical geometries with a range of wall-fluid interactions. As wall curvature increases, the slip length decreases dramatically for closely packed surfaces and increases for sparse ones. The magnitude of the changes depends on the crystallographic orientation and differs for flow along and perpendicular to the direction of curvature. These different patterns of behavior are related to the curvature-induced variation in the ratio of the spacing between fluid atoms to the spacing between minima in the potential from the solid surface. The results are consistent with a microscopic theory for the viscous friction between fluid and wall that expresses the slip length in terms of the lateral response of the fluid to the wall potential and the characteristic decay time of this response.

  17. The Mechanics, Geometry and Distribution of Strike Slip Faults in a Fold and Thrust Belt, County Clare, Ireland

    NASA Astrophysics Data System (ADS)

    Nenna, F. A.; Aydin, A.

    2010-12-01

    Fundamental structures such as opening mode joints and veins, and closing mode pressure solution seams (PSSs) can form dense orthogonal arrays in collisional deformation belts and play important roles in the initiation and development of larger scale faults. We describe the deformation processes and the evolution of fault architecture using systematic documentation of field observations from arrays of strike-slip faults in the Carboniferous Ross Sandstone. This unit is exposed on the Loop Head Peninsula, County Clare, Ireland and was subject to compressive stresses associated with the Variscan orogeny at the end of the Carboniferous producing broad regional east-west trending folds and also tight low-amplitude folds cored by thrust faults. Near these faults, orthogonal sets of PSSs and joints/veins form contemporaneous arrays with pressure solution seams that are sub-parallel to the thrust fault traces and fold axes. A stress or material rotation during the Variscan Orogeny (or perhaps a major second stage of deformation either in late phase of the orogeny or post-orogeny) has lead to left-lateral shear of the PSSs evidenced by pressure solution splays and pull-aparts between their sheared segments, and right-lateral shear on the joints/veins evidenced by splay fractures. The splays of the sheared joints are in the same orientation of the joints in the pull-aparts of the sheared PSSs with which they merge. This indicates that the shearing of the joints/veins and the PSSs was likely to have occurred simultaneously under the same remote loading conditions. With increased shear, extensive splay fractures and pull-apart networks form weak damage zones through which strike-slip faults systems develop with slip of up to 2km. As a higher proportion of the shear is resolved on the joint system than that of the PSS system, the more prominent strike-slip faults are sub-parallel to or slightly inclined to the pre-existing joint/vein set and have a right-lateral sense of slip

  18. Nonlinear dynamical triggering of slow slip

    SciTech Connect

    Johnson, Paul A; Knuth, Matthew W; Kaproth, Bryan M; Carpenter, Brett; Guyer, Robert A; Le Bas, Pierre - Yves; Daub, Eric G; Marone, Chris

    2010-12-10

    Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads ({approx}1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred

  19. Slip-Related Changes in Plantar Pressure Distribution, and Parameters for Early Detection of Slip Events

    PubMed Central

    Choi, Seungyoung; Cho, Hyungpil; Kang, Boram; Lee, Dong Hun; Kim, Mi Jung

    2015-01-01

    Objective To investigate differences in plantar pressure distribution between a normal gait and unpredictable slip events to predict the initiation of the slipping process. Methods Eleven male participants were enrolled. Subjects walked onto a wooden tile, and two layers of oily vinyl sheet were placed on the expected spot of the 4th step to induce a slip. An insole pressure-measuring system was used to monitor plantar pressure distribution. This system measured plantar pressure in four regions (the toes, metatarsal head, arch, and heel) for three events: the step during normal gait; the recovered step, when the subject recovered from a slip; and the uncorrected, harmful slipped step. Four variables were analyzed: peak pressure (PP), contact time (CT), the pressure-time integral (PTI), and the instant of peak pressure (IPP). Results The plantar pressure pattern in the heel was unique, as compared with other parts of the sole. In the heel, PP, CT, and PTI values were high in slipped and recovered steps compared with normal steps. The IPP differed markedly among the three steps. The IPPs in the heel for the three events were, in descending order (from latest to earliest), slipped, recovered, and normal steps, whereas in the other regions the order was normal, recovered, and slipped steps. Finally, the metatarsal head-to-heel IPP ratios for the normal, recovered, and slipped steps were 6.1±2.9, 3.1±3.0, and 2.2±2.5, respectively. Conclusion A distinctive plantar pressure pattern in the heel might be useful for early detection of a slip event to prevent slip-related injuries. PMID:26798603

  20. Uncorking Shallow Slip and the Slip History of the 2014 South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Brooks, B. A.; Minson, S. E.; Glennie, C. L.; Murray, J. R.; Hudnut, K. W.; Ericksen, T.; Langenheim, V. E.; Lockner, D. A.; Dawson, T. E.; Lutz, A. T.; Schwartz, D. P.; Lienkaemper, J. J.

    2015-12-01

    Shallow fault slip (< ~1km) during and immediately following earthquakes is poorly understood, largely because of challenges measuring deformation near a surface rupture. The need for better measurement is further motivated by an apparent deficit of shallow slip in regional source models of strike-slip earthquakes and by the suggestion that near-surface frictional heterogeneity over spatial scales of 100s of meters can control shallow fault slip. Here, we use a nascent mobile laser scanning technique to quantify with unprecedented detail the coseismic surface rupture and rapid post-seismic deformation from the 24 August, 2014 M6.0 South Napa earthquake. We infer shallow fault slip and find that both co- and post-seismic slip at depths of ~3-25 m significantly exceeds traditional measurements of surface displacements. There is no deficit in shallow slip: near-surface slip values are greater than maximum reported co-seismic fault slip values at depth. By ~ 1 month, afterslip along the southern portion of the fault accounted for as much shallow slip potency as the shallow co-seismic rupture on the northern portion. Further, we show that the afterslipping portion of the fault cuts across a ~3000 m thick sedimentary basin whereas the co-seismically ruptured portion does not. A rate and state friction model is consistent with the basin thickness, afterslip, and rock-sample mechanical measurements and strongly suggests that near-surface frictional heterogeneity controlled the distribution of coseismic and post-seismic shallow slip. In the future, we suggest that combining existing basin thickness data with active fault maps could provide more precise estimates of where surface rupture and/or afterslip may occur, both before, and in rapid response to, damaging earthquakes.

  1. Identification of bolted lap joints parameters in assembled structures

    NASA Astrophysics Data System (ADS)

    Ahmadian, Hamid; Jalali, Hassan

    2007-02-01

    Bolted lap joints have significant influence on the dynamical behaviour of the assembled structures due to creation of strong local flexibility and damping. In modelling the dynamical behaviour of assembled structures the joint interface model must be represented accurately. A nonlinear model for bolted lap joints and interfaces is proposed capable of representing the dominant physics involved in the joint such as micro/macro-slip. The joint interface is modelled using a combination of linear and nonlinear springs and a damper to simulate the damping effects of the joint. An estimate of the response of the structure with a nonlinear model for the bolted joint under external excitations is obtained using the method of multiple scales. The parameters of the model, i.e. the spring constants and the damper coefficient, are functions of normal and tangential stresses at the joint interface and are identified by minimizing the difference between the model predictions and the experimentally measured data.

  2. Ceramic joints

    DOEpatents

    Miller, Bradley J.; Patten, Jr., Donald O.

    1991-01-01

    Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

  3. Kids' Slips: What Young Children's Slips of the Tongue Reveal about Language Development

    ERIC Educational Resources Information Center

    Jaeger, Jeri J.

    2005-01-01

    The study of speech errors, or "slips of the tongue," is a time-honored methodology which serves as a window to the representation and processing of language and has proven to be the most reliable source of data for building theories of speech production planning. However, until "Kids' Slips," there has never been a corpus of such errors from…

  4. Spectrum of slip behaviour in Tohoku fault zone samples at plate tectonic slip rates

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.; Ito, Yoshihiro; Ujiie, Kohtaro; Kopf, Achim J.

    2015-11-01

    During the 2011 Tohoku-oki earthquake, extremely extensive coseismic slip ruptured shallow parts of the Japan Trench subduction zone and breached the sea floor. This part of the subduction zone also hosts slow slip events (SSE). The fault thus seems to have a propensity for slip instability or quasi-instability that is unexpected on the shallow portions of important fault zones. Here we use laboratory experiments to slowly shear samples of rock recovered from the Tohoku-oki earthquake fault zone as part of the Japan Trench Fast Drilling Project. We find that infrequent perturbations in rock strength appear spontaneously as long-term SSE when the samples are sheared at a constant rate of about 8.5 cm yr-1, equivalent to the plate-convergence rate. The shear strength of the rock drops by 3 to 6%, or 50 kPa to 120 kPa, over about 2 to 4 h. Slip during these events reaches peak velocities of up to 25 cm yr-1, similar to SSE observed in several circum-Pacific subduction zones. Furthermore, the sheared samples exhibit the full spectrum of fault-slip behaviours, from fast unstable slip to slow steady creep, which can explain the wide range of slip styles observed in the Japan Trench. We suggest that the occurrence of SSE at shallow depths may help identify fault segments that are frictionally unstable and susceptible to large coseismic slip propagation.

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

    SciTech Connect

    Yoshimi, K.; Hanada, S.; Yoo, M.H.

    1998-10-09

    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.

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

    DOEpatents

    Klein, Frederick F.

    1989-01-01

    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.

  7. The Scaling of the Slip Weakening Distance (Dc) With Final Slip During Dynamic Earthquake Rupture

    NASA Astrophysics Data System (ADS)

    Tinti, E.; Fukuyama, E.; Cocco, M.; Piatanesi, A.

    2005-12-01

    Several numerical approaches have been recently proposed to retrieve the evolution of dynamic traction during the earthquake propagation on extended faults. Although many studies have shown that the shear traction evolution as a function of time and/or slip may be complex, they all reveal an evident dynamic weakening behavior during faulting. The main dynamic parameters describing traction evolution are: the yield stress, the residual kinetic stress level and the characteristic slip weakening distance Dc. Recent investigations on real data yield the estimate of large Dc values on the fault plane and a correlation between Dc and the final slip. In this study, we focus our attention on the characteristic slip weakening distance Dc and on its variability on the fault plane. Different physical mechanisms have been proposed to explain the origin of Dc, some of them consider this parameter as a scale dependent quantity. We have computed the rupture history from several spontaneous dynamic models imposing a slip weakening law with prescribed Dc distributions on the fault plane. These synthetic models provide the slip velocity evolution during the earthquake rupture. We have therefore generated a set of slip velocity models by fitting the "true" slip velocity time histories with an analytical source time function. To this goal we use the Yoffe function [Tinti et al. 2005], which is dynamically consistent and allows a flexible parameterization. We use these slip velocity histories as a boundary condition on the fault plane to compute the traction evolution. We estimate the Dc values from the traction versus slip curves. We therefore compare the inferred Dc values with those of the original dynamic models and we found that the Dc estimates are very sensitive to the adopted slip velocity function. Despite the problem of resolution that limits the estimate of Dc from kinematic earthquake models and the tradeoff that exists between Dc and strength excess, we show that to

  8. Is frictional healing slip-dependent?

    NASA Astrophysics Data System (ADS)

    Bhattacharya, P.; Rubin, A. M.; Ryan, K. L.; Riviere, J. V.; Marone, C.

    2015-12-01

    Frictional re-strengthening of bare rock surfaces at very low stresses and near zero slip rate, as observed in the laboratory, is traditionally interpreted as showing support for purely time-dependent healing as embodied in the Aging law. However, while slide-hold-slide experiments on bare surfaces do show an apparent (purely) time-dependent increase in the static friction upon reslide, we show that the stress minima attained during the preceding holds show a strong slip-dependence which contradict the Aging law. A velocity strengthening Slip law explains such data much better. We also show that, large velocity step decreases, which drive the system far below steady state just like long holds, clearly support the slip-dependent response of the Slip law over the time-dependent healing contained in the Aging law. But, while time-dependent healing has an intuitive physical picture in terms of growth of the 'real contact area' with time, it is more difficult to ascribe one to slip-dependent healing. Here, we explore the possibility that the slip-dependence arises out of an interplay between contact `quality' and `quantity' at the scale of the asperity contacts. First, to further study the slip-dependence of healing, we carry out large velocity step decreases and sequences of long slide-hold-slides on both bare rock and gouge. Secondly, to probe the micro-mechanical origins of healing, we complement our mechanical data with amplitudes and travel time data of ultrasonic P- and S- waves transmitted across the sliding interface. While ultrasonic P-wave transmissivity has been used as a proxy for 'real contact area' in friction experiments by Nagata et al. (2012, 2014) before, the simultaneous use of P- and S-phases in our experiments is designed specifically to probe contact rheology. Initial results show strong correlations between changes in friction, transmitted wave amplitudes and travel times in response to changes in slip rate. We also observe important differences

  9. Fault zone roughness controls slip stability

    NASA Astrophysics Data System (ADS)

    Harbord, Christopher; Nielsen, Stefan; De Paola, Nicola

    2016-04-01

    Fault roughness is an important control factor in the mechanical behaviour of fault zones, in particular the frictional slip stability and subsequent earthquake nucleation. Despite this, there is little experimental quantification as to the effects of varying roughness upon rate- and state-dependant friction (RSF). Utilising a triaxial deformation apparatus and a novel adaptation of the direct shear methodology to simulate initially bare faults in Westerly Granite, we performed a series of velocity step frictional sliding experiments. Initial root mean square roughnesses (Sq) was varied in the range 6x10‑7 ‑ 2.4x10‑5 m. We also investigated the effects upon slip stability of normal stress variation in the range σn = 30 ‑ 200 MPa, and slip velocity between 0.1 ‑ 10 μm s‑1. A transition from stable sliding to unstable slip (manifested by stick-slip and slow slip events) was observed, depending on the parameter combination, thus covering the full spectrum of fault slip behaviours. At low normal stress (σn = 30MPa) smooth faults (Sq< 1x10‑6 m) are conditional unstable (stress drops on slow slip events upon velocity increase), with strongly velocity weakening friction. When normal stress is increased to intermediate values (σn = 100 ‑ 150 MPa), smooth faults (Sq< 1x10‑6 m) are fully unstable and generate seismic stick-slip behaviour. However at higher normal stress (σn = 200 MPa) a transition from unstable to stable sliding is observed for smooth faults, which is not expected using RSF stability criteria. At all conditions sliding is stable for rough faults (Sq> 1x10‑6 m). We find that instability can develop when the ratio of fault to critical stiffness kf kc > 10, or, alternatively, even when a ‑ b > 0 at σn = 150MPa, suggesting that bare surfaces may not strictly obey the R+S stability condition. Additionally we present white light interferometry and SEM analysis of experimentally deformed samples which provide information about the

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

    NASA Astrophysics Data System (ADS)

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

    1998-08-01

    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.

  11. Discrete Element Modeling of Stick-Slip Instability and Induced Microseismicity

    NASA Astrophysics Data System (ADS)

    Khazaei, Cyrus; Hazzard, Jim; Chalaturnyk, Rick

    2016-03-01

    Using Particle Flow Code, a discrete element model is presented in this paper that allows direct modeling of stick-slip behavior in pre-existing weak planes such as joints, beddings, and faults. The model is used to simulate a biaxial sliding experiment from literature on a saw-cut specimen of Sierra granite with a single fault. The fault is represented by the smooth-joint contact model. Also, an algorithm is developed to record the stick-slip induced microseismic events along the fault. Once the results compared well with laboratory data, a parametric study was conducted to investigate the evolution of the model's behavior due to varying factors such as resolution of the model, particle elasticity, fault coefficient of friction, fault stiffness, and normal stress. The results show a decrease in shear strength of the fault in the models with smaller particles, smaller coefficient of friction of the fault, harder fault surroundings, softer faults, and smaller normal stress on the fault. Also, a higher rate of displacement was observed for conditions resulting in smaller shear strength. An increase in b-values was observed by increasing the resolution or decreasing the normal stress on the fault, while b-values were not sensitive to changes in elasticity of the fault or its surrounding region. A larger number of recorded events were observed for the models with finer particles, smaller coefficient of friction of the fault, harder fault surroundings, harder fault, and smaller normal stress on the fault. The results suggest that it is possible for the two ends of a fault to be still while there are patches along the fault undergoing stick-slips. Such local stick-slips seem to provide a softer surrounding for their neighbor patches facilitating their subsequent stick-slips.

  12. Breddin's Graph For Fault and Slip Data

    NASA Astrophysics Data System (ADS)

    Célérier, B.

    A simple plot of rake versus strike of fault and slip or earthquake focal mechanism data provides insight into the stress regime that caused slippage on these faults provided one of the principal stress direction is near vertical. By overlaying an abacus on this plot, one can evaluate both the orientation of the horizontal principal stress directions and the stress tensor aspect ratio, (s1-s2)/(s1-s3), where s1, s2, s3 are the principal stress magnitudes ranked in decreasing order. The underlying geometrical properties are that the slip data that are near strike-slip, and that are mainly found on steeply dipping planes, constrain the horizontal principal stress directions whereas the slip data that are near dip-slip and that occur on shallow dipping planes striking away from the principal stress directions constrain the stress tensor aspect ratio. This abacus is an extension of the Breddin's abacus used to analyze two dimensional deformation in structural geology and it is used in a similar fashion. Its application to synthetic and natural monophase data show both its usefulness and limitation. It is not intended to replace stress inversion techniques because of limiting assumptions, but it is expected to provide insight into the complexity of natural data set from a simple viewpoint.

  13. Temporomandibular Joint, Closed

    MedlinePlus

    ... Oral Health > The Temporomandibular Joint, Closed The Temporomandibular Joint, Closed Main Content Title: The Temporomandibular Joint, Closed Description: The temporomandibular joint connects the lower ...

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Faults in the upper crust contain discrete slip surfaces which have absorbed a significant part of the shear displacement along them. Field measurements demonstrate that these surfaces are rough at all measurable scales and indicate that surfaces of relatively large-slip faults are statistically smoother than those of small-slip faults. However, post faulting and surface erosion process that might affect the geometry of outcrops cannot be discounted in such measurements. Here we present experimental results for the evolution of shear surface topography as function of slip distance and normal stress in direct shear experiments. A single prismatic fine grain limestone block is first fractured in tension mode using the four-point bending test methodology and then the fracture surface topography is scanned using a laser profilometer. We then shear the obtained tensile fracture surfaces in direct shear, ensuring the original fracture surfaces are in a perfectly matching configuration at the beginning of the shear test. First, shearing is conducted to distances varying from 5 to 15 mm under constant normal stress of 2MPa and a constant displacement rate of 0.05 mm/s using two closed-loop servo controlled hydraulic pistons, supplying normal and shear forces (Davidesko et al., 2014). In the tested configuration peak shear stress is typically attained after a shear displacement of about 2-3 mm, beyond which lower shear stress is required to continue shearing at the preset displacement rate of 0.05 mm/s as is typical for initially rough joints. Following some initial compression the interface begins to dilate and continues to do so until the end of the test. The sheared tensile fracture surface is then scanned again and the geometrical evolution, in term of RMS roughness and power spectral density (PSD) is analyzed. We show that shearing smooth the surface along all our measurements scales. The roughness ratio, measured by initial PSD / final PSD for each wavelength

  15. Quantifying slip balance in the earthquake cycle: Coseismic slip model constrained by interseismic coupling

    NASA Astrophysics Data System (ADS)

    Wang, Lifeng; Hainzl, Sebastian; Mai, P. Martin

    2015-12-01

    The long-term slip on faults has to follow, on average, the plate motion, while slip deficit is accumulated over shorter timescales (e.g., between the large earthquakes). Accumulated slip deficits eventually have to be released by earthquakes and aseismic processes. In this study, we propose a new inversion approach for coseismic slip, taking interseismic slip deficit as prior information. We assume a linear correlation between coseismic slip and interseismic slip deficit and invert for the coefficients that link the coseismic displacements to the required strain accumulation time and seismic release level of the earthquake. We apply our approach to the 2011 M9 Tohoku-Oki earthquake and the 2004 M6 Parkfield earthquake. Under the assumption that the largest slip almost fully releases the local strain (as indicated by borehole measurements), our results suggest that the strain accumulated along the Tohoku-Oki earthquake segment has been almost fully released during the 2011 M9 rupture. The remaining slip deficit can be attributed to the postseismic processes. Similar conclusions can be drawn for the 2004 M6 Parkfield earthquake. We also estimate the required time of strain accumulation for the 2004 M6 Parkfield earthquake to be ~25 years (confidence interval of [17, 43] years), consistent with the observed average recurrence time of ~22 years for M6 earthquakes in Parkfield. For the Tohoku-Oki earthquake, we estimate the recurrence time of ~500-700 years. This new inversion approach for evaluating slip balance can be generally applied to any earthquake for which dense geodetic measurements are available.

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

    USGS Publications Warehouse

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

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into 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

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

    USGS Publications Warehouse

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

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into 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

  18. Wall slip of bubbles in foams

    NASA Astrophysics Data System (ADS)

    Saugey, A.; Drenckhan, W.; Weaire, D.

    2006-05-01

    We present a computational analysis of the flow of liquid foam along a smooth wall, as encountered in the transport of foams in vessels and pipes. We concentrate on the slip of the bubbles at the wall and present some novel finite element calculations of this motion for the case of fully mobile gas/liquid interfaces. Our two-dimensional simulations provide for the first time the bubble shapes and entire flow field, giving detailed insight into the distribution of stresses and dissipation in the system. In particular, we investigate the relationship between the drag force and the slip velocity of the bubble, which for small slip velocities obeys power laws, as predicted by previous semianalytical treatments.

  19. Dislocation boundaries and active slip systems

    SciTech Connect

    Wert, J.A.; Hansen, N.

    1995-11-01

    Part of the dislocations which have participated in the plastic deformation of a polycrystalline metal are stored in dislocation boundaries in a two- or three-dimensional arrangement. The dislocation in such boundaries can be analyzed by determining the misorientation between neighboring crystallites and the boundary orientation. Information about the dislocations in the boundaries can also be obtained by an analysis of active slip systems based on the crystallite orientation and the imposed stress or strain state in combination with appropriate constraint conditions. In the present paper an analysis of the boundary dislocation structure and of the slip systems has been conducted for pure aluminium cold-rolled to a von Mises strain of 0.41. The results show that a substantial majority of dislocations in different types of dislocation boundaries are from the primary and conjugate slip system in the adjoining crystallites. A basis is therefore provided for integrating deformation structure observations with plastic deformation behavior.

  20. Slip, Crystal Orientation, and Damage Evolution During Thermal Cycling in High-Strain Wafer-Level Chip-Scale Packages

    NASA Astrophysics Data System (ADS)

    Zhou, Bite; Zhou, Quan; Bieler, Thomas R.; Lee, Tae-kyu

    2015-03-01

    Wafer-level chip-scale package samples with pre-cross-sectioned edge rows were thermally cycled to study microstructure evolution and damage development. Electron backscattered diffraction (EBSD) and high-energy x-ray diffraction were used to obtain Sn grain orientations and the average coefficient of thermal expansion normal to the board in every joint of the package for samples in the as-fabricated and thermally cycled conditions. The results indicated a near-random distribution of joint orientation. Optical, scanning electron microscopy, and EBSD methods were used to characterize microstructure changes in pre-cross-sectioned samples due to thermal cycling. Slip trace analysis and Orientation Imaging Microscopy™ (OIM) show that slip systems with high Schmid factors (estimated global shear stress based on the package neutral point) are responsible for the observed microstructure evolution during thermal cycling, which provides information about slip systems that are more easily activated. Two joints were analyzed in detail to evaluate slip activity at different stages of their thermal history. The first case showed that a solidification twin grain boundary misorientation deviated from the twin relationship due to slip activity during thermal cycling, which can influence damage development and the path of crack propagation. The second case showed a new grain orientation developing due to gradual lattice rotation about the Sn [110] axis by a continuous recrystallization mechanism. This rotation was correlated with the operation of slip system . Small tin whiskers emerged from the initially polished chip interface and grew with increasing thermal cycles until a crack developed in the solder that relieved the stress. As the local stresses are not known experimentally, this analysis provides observations that can be compared with a crystal plasticity model simulation.

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

    NASA Astrophysics Data System (ADS)

    Chen, T.; Luo, H.

    2013-12-01

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

  2. 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 ...

  3. Joint pain

    MedlinePlus

    ... or conditions. It may be linked to arthritis , bursitis , and muscle pain . No matter what causes it, ... Autoimmune diseases such as rheumatoid arthritis and lupus Bursitis Chondromalacia patellae Crystals in the joint: gout (especially ...

  4. Compliant joint

    NASA Technical Reports Server (NTRS)

    Eklund, Wayne D. (Inventor); Kerley, James J. (Inventor)

    1990-01-01

    A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

  5. Slip length measurement of gas flow.

    PubMed

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-16

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas. PMID:27505860

  6. Slip length measurement of gas flow

    NASA Astrophysics Data System (ADS)

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-01

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  7. Frictional Melting of Peridotite and Seismic Slip

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The evolution of the frictional strength along a fault at seismic slip rates (about 1 m/s) is one of the main factors controlling earthquake mechanics. In particular, friction-induced rock melting and melt lubrication during seismic slip may be typical at mantle depths, based on field studies, seismological evidence, torsion experiments and theoretical studies. To investigate the (1) dynamic strength of faults and (2) the frictional melting processes in mantle rocks, we performed 20 experiments with the Balmuccia peridotite in a high- velocity rotary shear apparatus. Experiments were conducted on cylindrical samples (21.8 mm in diameter) over a wide range of normal stresses (5.4 to 16.1 MPa), slip rates (0.23 to 1.14 m/s) and displacements (1.5 to 71 m). The dynamic strength of experimental faults evolved with displacement: after a peak (first strengthening) at the initiation of slip, fault strength abruptly decreased (first weakening), then increased (second strengthening) and eventually decreased (second weakening) towards a steady-state value. The microstructural and geochemical (FE-SEM, EPMA and EDS) investigation of the slipping zone from experiments interrupted at different displacements, revealed that second strengthening was associated with the production of a grain-supported melt-poor layer, while second weakening and steady-state with the formation of a continuous melt-rich layer. The temperature of the frictional melt was up to 1780 Celsius. Microstructures formed during the experiments were identical to those found in natural ultramafic pseudotachylytes. By performing experiments for increasing normal stresses and slip rates, steady-state shear stress slightly increased with increasing normal stress (friction coefficient of 0.15) and, for a given normal stress, decreased with increasing slip rate. The dependence of steady-state shear stress with normal stress and slip rate is described by a constitutive equation for melt lubrication. The presence of

  8. Slipping magnetic reconnection in coronal loops.

    PubMed

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

    2007-12-01

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

  9. Momentum compaction and phase slip factor

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

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

  10. The mechanics of stick-slip

    USGS Publications Warehouse

    Byerlee, J.D.

    1970-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Chen, T.

    2009-12-01

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

  12. Slip rates across the sinistral slip fault system of the Shan Plateau, northern SE Asia

    NASA Astrophysics Data System (ADS)

    Shi, X.; Sieh, K.; Wang, Y.; Liu, J.; Weldon, R. J.; Feng, L.; Chan, C. H.

    2014-12-01

    The sinistral-slip fault system of the Shan Plateau, arcing around the eastern Himalayan syntaxis and extending > 700 km from northwest to southeast, poses a high seismic hazard in northern SE Asia. Knowing slip rates and earthquake recurrence intervals of these faults is key to better quantification of that hazard. However, estimates of slip rates along the fault system remain poorly constrained. Here we report a preliminary estimate of the slip rate across the fault system from available campaign GPS velocities. We projected the horizontal GPS velocity vectors relative to the Sunda block reference frame perpendicular to the general strike (~ 240°) of the sinistral faults. The velocity profile shows a gradient of ~ 9 mm/yr over a distance of ~ 550 km that crosses 8 faults, from the Dayingjiang fault in the northwest to the Mengxing fault in the southeast. This suggests the average slip rate across each fault in the system is ~ 1 mm/yr. The 9 mm/yr of GPS velocity gradient across the fault system, however, is only half of the long-term rates determined from offsets of major rivers, ridges and plutons. These geological determinations suffer, however, from poor dating constraints. The discrepancy between the geodetic and geological analyses highlights the need of reliable constraints on slip rates along each of the faults. We have begun field work aimed at determining the slip rate of one of these, the Jinghong fault.

  13. Update on slip and wear in multi-layer azimuth track systems

    NASA Astrophysics Data System (ADS)

    Juneja, Gunjeet; Kan, Frank W.; Antebi, Joseph

    2006-06-01

    Many antennas, such as the 100-m Green Bank Telescope, use a wheel-on-track systems in which the track segments consist of wear plates mounted on base plates. The wear plates are typically 2 to 3 inches thick and are case hardened or through hardened. The base plates are usually 3 to 4 times thicker than the wear plates and are not hardened. The wear plates are typically connected to the base plates using bolts. The base plates are supported on grout and anchored to the underlying concrete foundation. For some antennas, slip has been observed between the wear plate and base plate, and between the base plate and the grout, with the migration in the wheel rolling direction. In addition, there has been wear at the wear plate/base plate interface. This paper is an update on the evaluation of GBT track retrofit. The paper describes the use of three-dimensional non-linear finite element analyses to understand and evaluate the behavior of (1) the existing GBT wheel-on-track system with mitered joints, and (2) the various proposed modifications. The modifications include welding of the base plate joints, staggering of the wear plate joints from the base plate joints, changing thickness of the wear plate, and increasing bolt diameter and length. Parameters included in the evaluation were contact pressure, relative slip, wear at the wear plate/base plate interface, and bolt shears and moments.

  14. 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...

  15. SYNTHESIS OF ORGANIC EPOXIDES USING A SPINNING TUBE-IN-TUBE REACTOR

    EPA Science Inventory

    The U.S. Environmental Protectiion 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 chemcial synthesis. The STT...

  16. 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...

  17. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

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

    PubMed Central

    Du, Shuang; Gao, Yang

    2012-01-01

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

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

    PubMed

    Du, Shuang; Gao, Yang

    2012-01-01

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

  1. Hydrodynamic slip length as a surface property.

    PubMed

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G P

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems. PMID:26986407

  2. Hydrodynamic slip length as a surface property

    NASA Astrophysics Data System (ADS)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.

  3. Beyond the no-slip boundary condition.

    PubMed

    Brenner, Howard

    2011-10-01

    This paper offers a simple macroscopic approach to the question of the slip boundary condition to be imposed upon the tangential component of the fluid velocity at a solid boundary. Plausible reasons are advanced for believing that it is the energy equation rather than the momentum equation that determines the correct fluid-mechanical boundary condition. The scheme resulting therefrom furnishes the following general, near-equilibrium linear constitutive relation for the slip velocity of mass along a relatively flat wall bounding a single-component gas or liquid: (v(m))(slip)=-α∂lnρ/∂s|(wall), where α and ρ are, respectively, the fluid's thermometric diffusivity and mass density, while the length δs refers to distance measured along the wall in the direction in which the slip or creep occurs. This constitutive relation is shown to agree with experimental data for gases and liquids undergoing thermal creep or pressure-driven viscous creep at solid surfaces. PMID:22181263

  4. PRODUCTION OF SLIP CAST CALCIA HOLLOWWARE

    DOEpatents

    Stoddard, S.D.; Nuckolls, D.E.; Cowan, R.E.

    1963-12-31

    A method for producing slip cast calcia hollow ware in which a dense calcia grain is suspended in isobutyl acetate or a mixture of tertiary amyl alcohol and o-xylene is presented. A minor amount of triethanolamine and oleic acid is added to the suspension vehicle as viscosity adjusting agents and the suspension is cast in a plaster mold, dried, and fired. (AEC)

  5. 7 CFR 51.491 - Wet slip.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet slip. 51.491 Section 51.491 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND...

  6. 7 CFR 51.491 - Wet slip.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet slip. 51.491 Section 51.491 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND...

  7. Slip casting and nitridation of silicon powder

    NASA Astrophysics Data System (ADS)

    Seiko, Y.

    1985-03-01

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

  8. Slip casting and nitridation of silicon powder

    NASA Technical Reports Server (NTRS)

    Seiko, Y.

    1985-01-01

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

  9. Oblique slip in Laramide foreland arches

    SciTech Connect

    Erslev, E.A.; Selvig, B.; Molzer, P. . Dept. of Earth Resources)

    1993-03-01

    Don Wise was one of the first structural geologists to recognize the complex, four-dimensional (space and time) nature of basement-involved faulting in the Rocky Mountain foreland. His focus on both small scale kinematic indicators and regional tectonic hypotheses has provided a launching point for many Rocky Mountain geologists. The implications of the anastomosing patterns of Laramide foreland arches on models of regional stress and strain have provoked considerable debate. Hypotheses range from those invoking multiple stages of lateral compression from different directions to single-stage models necessitating a component of strike-slip motion in east-west and north-south arches. These hypotheses were tested using slickenline analysis of minor faulting in structures with different orientations. In Wyoming, structures paralleling the dominant northwest structural trend have slickenlines in the NE-SW vertical plane, consistent with shortening and compression in this direction. The east-west Owl Creek and Casper Mountain structures also have NE-SW trending slickenlines, indicating slip oblique to these arches. In Colorado, minor faults in the north-south margin of the northeastern Front Range also indicate oblique slip, with shortening in the NE-SW quadrant. The actual trend of the slickenlines is more easterly, however, suggesting a change of slip trajectory with latitude, not time, possibly in response to identation by the Colorado Plateau.

  10. Multi-level slip-link modeling

    NASA Astrophysics Data System (ADS)

    Schieber, Jay

    2014-03-01

    That the dynamics of concentrated, high-molecular-weight polymers are largely governed by entanglements is now widely accepted, and typically understood by the tube model. Although the original idea for slip-links was proposed at the same time as tubes, only recently have detailed, quantitative mathematical models arisen based on this picture. We argue here for the use of a slip-link model that has strong connections to atomistic, multichain levels of description, agrees with non-equilibrium thermodynamics, applies to any chain architecture and can be used in linear or non-linear rheology. We present a hierarchy of slip-link models that are connected to each other through successive coarse graining. One might choose a particular member of the hierarchy depending on the problem at hand, in order to minimize computational effort. In particular, the most detailed level of description has four parameters, three of which can be determined directly from atomistic simulations. The least-detailed member is suitable for predicting non-linear, non-uniform flow fields. We will show how using this hierarchy of slip-link models we can make predictions about the nonlinear rheology of monodisperse homopolymer melts, polydisperse melts, or blends of different architectures.

  11. Slip Dynamics in Small Scale Crystals

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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

  13. Spatial variations in slip deficit on the central San Andreas Fault from InSAR

    NASA Astrophysics Data System (ADS)

    Ryder, Isabelle; Bürgmann, Roland

    2008-12-01

    We use ERS InSAR measurements to record spatial variations in creep rate along the creeping segment of the San Andreas Fault (SAF), California, between 1992 and 2001. Inversion of geodetic data yields a slip rate distribution along the creeping segment, which is used for first-order moment release and deficit calculations. We present a time-averaged spatial picture of surface deformation and associated subsurface creep. An interferometric stack is constructed from 12 interferograms that show good coherence. For the decade of observation, the total right-lateral offset spanned by the data is ~34 mmyr-1. Along most of the length of the creeping segment, this offset occurs within a narrow (<2 km) zone close to the fault trace. In the northern part, a minor part of the offset is taken up by the nearby Calaveras-Paicines Fault. In general, the observed rates of surface creep are consistent with those obtained by several other studies for a longer and/or earlier period of time, using different geodetic methods. This suggests that the average creep rate has been constant over a period of almost four decades. A joint GPS-InSAR inversion implies that the shallow creep rate is variable along strike, reaching up to 31.5 +/- 1 mmyr-1 in the central section of the creeping segment, tapering off along-strike to the south and becoming partitioned across two subparallel faults in the north. The deep slip rate beneath the seismogenic layer is 33 +/- 3 mmyr-1. The difference between shallow and deep slip rates suggests that there is a shallow slip deficit on the creeping segment of the SAF (CSAF). Moment release rate due to aseismic slip is approximately three orders of magnitude greater than seismic moment release. The annual creep on the CSAF is equivalent to the moment released in a M 6 earthquake. The equivalent moment of the slip deficit relative to the deep slip rate is between 4.1 × 1017 and 8.4 × 1017 N myr-1, which is equivalent to a magnitude 5.7-5.9 earthquake. Over a

  14. Volcanism and aseismic slip in subduction zones

    SciTech Connect

    Acharya, H.

    1981-01-10

    The spatial and temporal relationship of volcanism to the occurrence of large earthquakes and convergent plate motion is examined. The number of volcanic eruptions per year in a convergent zone is found to be linearly related to the aseismic slip component of plate motion. If the aseismic slip rate is low (coupling between converging plates is strong), then the primary manifestation of tectonic activity is the occurrence of large earthquakes with only infrequent volcanic activity. If, however, the aseismic slip rate is high (coupling is weak), then there are few large earthquakes, and volcanism is the principal manifestation of tectonic activity. This model is consistent with the spatial distribution of large earthquakes and active volcanoes in the circum-Pacific area. It is tested by examining the extent of volcanic activity in the rupture zones of the 1952--1973 sequence of earthquakes in the Japan--Kurile Islands area. The number of volcanic euptions along these zones during the interval between large earthquakes is used to compute the aseismic slip rates for these segments, based on the relationship developed in this study. The aseismic slip rates so computed agree with those determined from the earthquake history of the area and rates of plate motion. The agreement suggests that in the interval between large earthquakes, the aseismic plate motion is manifested in a specific number of volcanic eruptions. Therefore in areas with adequate historial data it should be possible to use the model developed in this study to monitor volcanic eruptions for long-term prediction of large earthquakes.

  15. The structure of slip-pulses and supershear ruptures driving slip in bimaterial friction

    PubMed Central

    Shlomai, Hadar; Fineberg, Jay

    2016-01-01

    The most general frictional motion in nature involves bimaterial interfaces, when contacting bodies possess different elastic properties. Frictional motion occurs when the contacts composing the interface separating these bodies detach via propagating rupture fronts. Coupling between slip and normal stress variations is unique to bimaterial interfaces. Here we use high speed simultaneous measurements of slip velocities, real contact area and stresses to explicitly reveal this bimaterial coupling and its role in determining different classes of rupture modes and their structures. We directly observe slip-pulses, highly localized slip accompanied by large local reduction of the normal stress near the rupture tip. These pulses propagate in the direction of motion of the softer material at a selected (maximal) velocity and continuously evolve while propagating. In the opposite direction bimaterial coupling favors crack-like ‘supershear' fronts. The robustness of these structures shows the importance of bimaterial coupling to frictional motion and modes of frictional dissipation. PMID:27278687

  16. The structure of slip-pulses and supershear ruptures driving slip in bimaterial friction.

    PubMed

    Shlomai, Hadar; Fineberg, Jay

    2016-01-01

    The most general frictional motion in nature involves bimaterial interfaces, when contacting bodies possess different elastic properties. Frictional motion occurs when the contacts composing the interface separating these bodies detach via propagating rupture fronts. Coupling between slip and normal stress variations is unique to bimaterial interfaces. Here we use high speed simultaneous measurements of slip velocities, real contact area and stresses to explicitly reveal this bimaterial coupling and its role in determining different classes of rupture modes and their structures. We directly observe slip-pulses, highly localized slip accompanied by large local reduction of the normal stress near the rupture tip. These pulses propagate in the direction of motion of the softer material at a selected (maximal) velocity and continuously evolve while propagating. In the opposite direction bimaterial coupling favors crack-like 'supershear' fronts. The robustness of these structures shows the importance of bimaterial coupling to frictional motion and modes of frictional dissipation. PMID:27278687

  17. Effective slip lengths for longitudinal shear flow over partial-slip circular bubble mattresses

    NASA Astrophysics Data System (ADS)

    Crowdy, Darren

    2015-12-01

    The problem of longitudinal shear flow over a circular bubble mattress with partial slip and protrusion angle 90o is solved in a quasi-analytical fashion by a novel transform scheme recently devised by the author. The general approach can be readily adapted to other mixed boundary value problems. From the analysis explicit approximations for the effective slip lengths are found as a function of the Navier-slip parameter and the area fraction of the surface covered by protrusions. These new approximation formulas for the slip lengths both unify and extend those based on empirical polynomial fits to numerical data given recently by Ng and Wang (2011 Fluid Dyn. Res. 43 065504).

  18. The structure of slip-pulses and supershear ruptures driving slip in bimaterial friction

    NASA Astrophysics Data System (ADS)

    Shlomai, Hadar; Fineberg, Jay

    2016-06-01

    The most general frictional motion in nature involves bimaterial interfaces, when contacting bodies possess different elastic properties. Frictional motion occurs when the contacts composing the interface separating these bodies detach via propagating rupture fronts. Coupling between slip and normal stress variations is unique to bimaterial interfaces. Here we use high speed simultaneous measurements of slip velocities, real contact area and stresses to explicitly reveal this bimaterial coupling and its role in determining different classes of rupture modes and their structures. We directly observe slip-pulses, highly localized slip accompanied by large local reduction of the normal stress near the rupture tip. These pulses propagate in the direction of motion of the softer material at a selected (maximal) velocity and continuously evolve while propagating. In the opposite direction bimaterial coupling favors crack-like `supershear' fronts. The robustness of these structures shows the importance of bimaterial coupling to frictional motion and modes of frictional dissipation.

  19. Viscous Moment, Mechanism of Slow Slip, and Subduction Megathrust Viscosity

    NASA Astrophysics Data System (ADS)

    Fagereng, A.

    2015-12-01

    Slow slip events (SSEs) represent transient slip velocities slower than earthquakes but faster than steady, average plate motion. SSEs repeating at the same location have characteristic slip magnitude and duration. Contrary to earthquakes, however, average slip relates to neither duration nor area. Variations in duration, slip, and slip rate can instead be tied to variations in effective viscosity, calculated from a viscous definition of moment. In this paradigm, the observation that deep slow slip events are slower and longer, implies a higher effective viscosity than in shallower, colder SSEs. Observed variations in effective viscosity and slip rate can be interpreted in terms of differences in driving stress and shear zone width, and likely arise in anastomosing shear zones containing a heterogeneous mixture of materials.

  20. Development of compact slip detection sensor using dielectric elastomer

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  1. Downscaling of slip distribution for strong earthquakes

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    We intend to develop a downscaling model to enhance the earthquake slip distribution resolution. Slip distributions have been obtained by other researchers using various inversion methods. As a downscaling model, we are discussing fractal models that include mono-fractal models (fractional Brownian motion, fBm; fractional Lévy motion, fLm) and multi-fractal models as candidates. Log - log-linearity of k (wave number) versus E (k) (power spectrum) is the necessary condition for fractality: the slip distribution is expected to satisfy log - log-linearity described above if we can apply fractal model to a slip distribution as a downscaling model. Therefore, we conducted spectrum analyses using slip distributions of 11 earthquakes as explained below. 1) Spectrum analyses using one-dimensional slip distributions (strike direction) were conducted. 2) Averaging of some results of power spectrum (dip direction) was conducted. Results show that, from the viewpoint of log - log-linearity, applying a fractal model to slip distributions can be inferred as valid. We adopt the filtering method after Lavallée (2008) to generate fBm/ fLm. In that method, generated white noises (random numbers) are filtered using a power law type filter (log - log-linearity of the spectrum). Lavallée (2008) described that Lévy white noise that generates fLm is more appropriate than the Gaussian white noise which generates fBm. In addition, if the 'alpha' parameter of the Lévy law, which governs the degree of attenuation of tails of the probability distribution, is 2.0, then the Lévy distribution is equivalent to the Gauss distribution. We analyzed slip distributions of 11 earthquakes: the Tohoku earthquake (Wei et al., 2011), Haiti earthquake (Sladen, 2010), Simeulue earthquake (Sladen, 2008), eastern Sichuan earthquake (Sladen, 2008), Peru earthquake (Konca, 2007), Tocopilla earthquake (Sladen, 2007), Kuril earthquake (Sladen, 2007), Benkulu earthquake (Konca, 2007), and southern Java

  2. Joint lubrication.

    PubMed

    McCutchen, C W

    1983-01-01

    The fine-pored, easily compressed articular cartilage provides animal joints with self-pressurized hydrostatic (weeping) lubrication. The solid skeletons of the cartilages press against each other, but so lightly that their rubbing is lubricated successfully by synovial fluid--a boundary lubricant too weak to lubricate ordinary bearings. PMID:6317095

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

    USGS Publications Warehouse

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

    1998-01-01

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

  4. What do formal inversions of space geodetic data tell us about fault slip rates? Examples from Southern California. (Invited)

    NASA Astrophysics Data System (ADS)

    Lindsey, E. O.; Fialko, Y.

    2010-12-01

    We use secular velocities from the continuous GPS data provided by the Plate Boundary Observatory (PBO) and Scripps Orbit Permanent Array Center (SOPAC), campaign GPS data (SCEC Crustal Motion Model) and InSAR data from the ERS-1/2 and ENVISAT satellites spanning nearly 20 years (1992-2010) to estimate the contemporaneous slip rates and locking depths on the Southern San Andreas fault (SAF), the San Jacinto fault (SJF) and the Elsinore fault. The model parameter space was interrogated using a Gibbs sampler, a Markov chain Monte Carlo algorithm which naturally approximates the joint probability distribution for the model parameters and allows for a formal evaluation of model uncertainties and trade-offs. We performed joint inversions of all available space geodetic data using the Savage and Burford (1973) dislocation model. Previous geodetic estimates of slip rates in this region based on dislocation models have generally inferred a higher slip velocity on the SAF (21-26 mm/yr), and a lower velocity on the SJF (12-19 mm/yr) (Becker et al. 2005, Fay and Humphreys 2005, Meade and Hager 2005, Fialko 2006). These "geodetic" slip rates are generally higher than geologic estimates representing average slip rates on time scales of 10^4-10^6 years. We investigate implications of fault geometry such as a non-vertical SAF and a "blind" segment of the SJF (Fialko 2006; Lin et al. 2007). Using the fault geometry motivated by these recent studies, we estimate a slip rate of 16(+/-2) mm/yr for the southern SAF, and a combined slip rate of 21(+/-3) mm/yr for the two closely spaced branches of the southern San Jacinto fault (the Coyote Creek fault and the blind southern continuation of the Clark fault). The locking depths are estimated at 7(+/-3) km and 14(+/-6) km for the SAF and SJF, respectively. For the SJF, we note a significant trade-off between fault velocity and locking depth, with the best-fitting values occurring at the lower end of the formally estimated parameter ranges

  5. Relationships between Slow Slip and Earthquakes at the Brittle-Ductile Transition of Subduction Zones

    NASA Astrophysics Data System (ADS)

    Brudzinski, M. R.; Colella, H.; Skoumal, R.; Cabral-Cano, E.; Arciniega-Ceballos, A.; Graham, S. E.; DeMets, C.; Sit, S. M.; Holtkamp, S. G.

    2014-12-01

    Following the discovery of episodic tremor and slip, one of the key questions raised is whether the phenomena can be a harbinger of megathrust earthquakes. Several recent large subduction earthquakes have provided an opportunity to investigate this question. The March 20, 2012 Mw 7.4 Ometepec earthquake in southern Mexico represents one such opportunity as it occurred in an area with a joint seismic and geodetic network in the source region that can examine whether patterns in the episodic tremor and slip were related to the earthquake. GPS data indicate that a 5-month-long slow slip episode (SSE) migrated toward and reached the vicinity of the mainshock source zone a few weeks before the earthquake. With multi-station waveform matching of templates constructed from visible aftershock signals, we find an increase in seismic activity during the SSE. The fault patches represented by these templates fill in the gap between the earthquake epicenter and the primary SSE. Analysis of other seismic swarms in Oaxaca near the down-dip end of the seismogenic zone with multi-station template matching also shows an increase in seismicity during SSEs. This evidence adds to a growing number of published accounts that indicate slow slip, whether geodetically or seismically inferred, is becoming a more commonly observed pre-earthquake signature. We use RSQSim earthquake simulations to model these scenarios using a subduction interface with a shallow seismogenic zone, deep SSE zone, and a microseismicity zone in between. Simulations where the microseismicity zone is assigned varying effective normal stresses and slip speeds over small distances generate cases in which microseismicity primarily occurs when a SSE migrates up-dip to the point enough stress is transferred to nucleate an earthquake on elements with a higher effective normal stress. Together these observations support the notion that SSE can trigger traditional earthquakes, not just tremor and low-frequency earthquakes.

  6. Relationships among certain joint constitutive models.

    SciTech Connect

    Segalman, Daniel Joseph; Starr, Michael James

    2004-09-01

    In a recent paper, Starr and Segalman demonstrated that any Masing model can be represented as a parallel-series Iwan model. A preponderance of the constitutive models that have been suggested for simulating mechanical joints are Masing models, and the purpose of this discussion is to demonstrate how the Iwan representation of those models can yield insight into their character. In particular, this approach can facilitate a critical comparison among numerous plausible constitutive models. It is explicitly shown that three-parameter models such as Smallwood's (Ramberg-Osgood) calculate parameters in such a manner that macro-slip is not an independent parameter, yet the model admits macro-slip. The introduction of a fourth parameter is therefore required. It is shown that when a macro-slip force is specified for the Smallwood model the result is a special case of the Segalman four-parameter model. Both of these models admit a slope discontinuity at the inception of macro-slip. A five-parameter model that has the beneficial features of Segalman's four-parameter model is proposed. This model manifests a force-displacement curve having a continuous first derivative.

  7. Interfacial Slip in Polymer Blends with Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ortiz, Joseph; Jaber, Eihab; Gersappe, Dilip

    2010-03-01

    The interfacial region in polymer blends has been identified as a low viscosity region in which considerable slip can occur when the blend is subjected to shear forces. Here we use Molecular Dynamics simulations to establish the role that added nanoparticle fillers play in modifying the interfacial rheology. By choosing conditions under which the fillers are localized, either in the two phases or at the interface, we can look at the interplay between the strengthening capability of nanoparticles and the change in the interfacial slip behavior. We examine particle size, attraction between the particle and the polymer component, and the amount of filler in the material. Our studies are performed both above and below the point at which the filler particles form a transient network in the blend.

  8. Interfacial Slip in Polymer Blends with Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ortiz, Joseph; Jaber, Eihab; Gersappe, Dilip

    2009-03-01

    The interfacial region in polymer blends has been identified as a low viscosity region in which considerable slip can occur when the blend is subjected to shear forces. Here we use Molecular Dynamics simulations to establish the role that added nanoparticle fillers play in modifying the interfacial rheology. By choosing conditions under which the fillers are localized, either in the two phases or at the interface, we can look at the interplay between the strengthening capability of nanoparticles and the change in the interfacial slip behavior. We examine particle size, attraction between the particle and the polymer component, and the amount of filler in the material. Our studies are performed both above and below the point at which the filler particles form a transient network in the blend.

  9. Interfacial slip in polymer blends with nanoparticles

    NASA Astrophysics Data System (ADS)

    Ortiz, Joseph; Jaber, Eihab; Gersappe, Dilip

    2008-03-01

    The interfacial region in polymer blends has been identified as a low viscosity region in which considerable slip can occur when the blend is subjected to shear forces. Here, we use Molecular Dynamics simulations to establish the role that added nanofiller particles play in modifying the interfacial rheology. By choosing conditions under which the fillers are localized either in the two phases, or at the interface we can look at the interplay between the strengthening capability of nanoparticles, and the change in the interfacial slip behavior. We examine particle size, attraction between the particle and the polymer component and the amount of filler in the material. Our studies are performed both above and below the point at which the filler particles form a transient network in the blend.

  10. Phase Slips in Oscillatory Hair Bundles

    NASA Astrophysics Data System (ADS)

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production.

  11. Phase Slips in Oscillatory Hair Bundles

    PubMed Central

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-01-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  12. Phase slips in oscillatory hair bundles.

    PubMed

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  13. Frictional melting of peridotite and seismic slip

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    The evolution of the frictional strength along a fault at seismic slip rates (about 1 m/s) is a key factor controlling earthquake mechanics. At mantle depths, friction-induced melting and melt lubrication may influence earthquake slip and seismological data. We report on laboratory experiments designed to investigate dynamic fault strength and frictional melting processes in mantle rocks. We performed 20 experiments with Balmuccia peridotite in a high-velocity rotary shear apparatus and cylindrical samples (21.8 mm in diameter) over a wide range of normal stresses (5.4-16.1 MPa), slip rates (0.23-1.14 m/s), and displacements (1.5-71 m). During the experiments, shear stress evolved with cumulative displacement in five main stages (stages 1-5). In stage 1 (first strengthening), the coefficient of friction μ increased up to 0.4-0.7 (first peak in friction). In stage 2 (abrupt first weakening), μ decreased to about 0.25-0.40. In stage 3 (gradual second strengthening), shear stress increased toward a second peak in friction (μ = 0.30-0.40). In stage 4 (gradual second weakening), the shear stress decreased toward a steady state value (stage 5) with μ = 0.15. Stages 1 and 2 are of too short duration to be investigated in detail with the current experimental configuration. By interrupting the experiments during stages 3, 4, and 5, microstructural (Field Emission Scanning Electron Microscope) and geochemical (Electron Probe Micro-Analyzer and Energy Dispersive X-Ray Spectroscopy) analysis of the slipping zone suggest that second strengthening (stage 3) is associated with the production of a grain-supported melt-poor layer, while second weakening (stage 4) and steady state (stage 5) are associated with the formation of a continuous melt-rich layer with an estimated temperature up to 1780°C. Microstructures formed during the experiments were very similar to those found in natural ultramafic pseudotachylytes. By performing experiments at different normal stresses and slip

  14. Wall slip and fluidity in emulsion flow

    NASA Astrophysics Data System (ADS)

    Paredes, José; Shahidzadeh, Noushine; Bonn, Daniel

    2015-10-01

    The microscopic origin of apparent wall slip is studied systematically using a confocal laser scanning microscope coupled to a rheometer. We obtain flow curves on a model emulsion from classical macroscopic measurements that are compared with flow curves obtained from microscopic measurements. By controlling the wetting properties of the shearing walls, we show that the characteristic length used in the so-called fluidity model, proposed by Goyon et al. [Nature (London) 454, 84 (2008), 10.1038/nature07026], can be understood in terms of roughness induced by adsorbed droplets on the surface. Additionally, we disentangle two different effects that contribute to the difference between micro- and macrorheology. Both effects manifest themselves as gap-dependent viscosities due to either the formation of a lubricating layer close to the shearing walls or cooperative effects when the flow is strongly confined. Finally, we show that the cooperative effects can also be translated into an effective slip velocity.

  15. Origin and characterization of different stick-slip friction mechanisms

    SciTech Connect

    Berman, A.D.; Ducker, W.A.; Israelachvili, J.N.

    1996-09-18

    Mechanical parts often move, not smoothly, but in jerks known as stick-slip. Stick-slip motion may be regular (repetitive or periodic) or irregular (erratic or intermittent). In the case of frictional sliding, stick-slip can have serious and often undesirable consequences - resulting in noise (chatter), high energy loss (friction), surface damage (wear), and component failure. We review the origins of stick-slip friction and present new experimental results on model surfaces that clarify its different origins, its dependence on experimental conditions or `system parameters`, and how stick-slip can be controlled in practical situations. 20 refs., 10 figs., 1 tab.

  16. IMPROVED MAGNESIUM OXIDE SLIP CASTING METHOD

    DOEpatents

    Stoddard, S.D.; Nuckolls, D.E.

    1963-12-31

    A process for making an aqueous magnesium oxide slip casting slurry comprising the steps of mixing finely ground fused magnesium oxide with water, milling the slurry for at least 30 hours at a temperature of 2-10 deg C (the low temperature during milling inhibiting the formation of hydrated magnesium oxide), discharging the slurry from the mill, adding hydrochloric acid as a deflocculent, and adding a scum inhibitor is presented. (AEC)

  17. Slip complexity in earthquake fault models.

    PubMed Central

    Rice, J R; Ben-Zion, Y

    1996-01-01

    We summarize studies of earthquake fault models that give rise to slip complexities like those in natural earthquakes. For models of smooth faults between elastically deformable continua, it is critical that the friction laws involve a characteristic distance for slip weakening or evolution of surface state. That results in a finite nucleation size, or coherent slip patch size, h*. Models of smooth faults, using numerical cell size properly small compared to h*, show periodic response or complex and apparently chaotic histories of large events but have not been found to show small event complexity like the self-similar (power law) Gutenberg-Richter frequency-size statistics. This conclusion is supported in the present paper by fully inertial elastodynamic modeling of earthquake sequences. In contrast, some models of locally heterogeneous faults with quasi-independent fault segments, represented approximately by simulations with cell size larger than h* so that the model becomes "inherently discrete," do show small event complexity of the Gutenberg-Richter type. Models based on classical friction laws without a weakening length scale or for which the numerical procedure imposes an abrupt strength drop at the onset of slip have h* = 0 and hence always fall into the inherently discrete class. We suggest that the small-event complexity that some such models show will not survive regularization of the constitutive description, by inclusion of an appropriate length scale leading to a finite h*, and a corresponding reduction of numerical grid size. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:11607669

  18. Slip-trace-induced vicinal step destabilization

    NASA Astrophysics Data System (ADS)

    Coupeau, C.; Camara, O.; Drouet, M.; Durinck, J.; Bonneville, J.; Colin, J.; Grilhé, J.

    2016-01-01

    Gold single crystals were deformed by uniaxial compression tests with the help of an experimental apparatus that allows one to characterize in situ, by UHV scanning tunneling microscopy, the evolution of surface structures under stress. It is demonstrated that the slip traces resulting from the emergence of moving dislocations at the free surface highly modify the organization of the vicinal steps. A model based on energetic considerations is proposed and discussed to explain the observed phenomenon.

  19. Surface slip during large Owens Valley earthquakes

    NASA Astrophysics Data System (ADS)

    Haddon, E. K.; Amos, C. B.; Zielke, O.; Jayko, A. S.; Bürgmann, R.

    2016-06-01

    The 1872 Owens Valley earthquake is the third largest known historical earthquake in California. Relatively sparse field data and a complex rupture trace, however, inhibited attempts to fully resolve the slip distribution and reconcile the total moment release. We present a new, comprehensive record of surface slip based on lidar and field investigation, documenting 162 new measurements of laterally and vertically displaced landforms for 1872 and prehistoric Owens Valley earthquakes. Our lidar analysis uses a newly developed analytical tool to measure fault slip based on cross-correlation of sublinear topographic features and to produce a uniquely shaped probability density function (PDF) for each measurement. Stacking PDFs along strike to form cumulative offset probability distribution plots (COPDs) highlights common values corresponding to single and multiple-event displacements. Lateral offsets for 1872 vary systematically from ˜1.0 to 6.0 m and average 3.3 ± 1.1 m (2σ). Vertical offsets are predominantly east-down between ˜0.1 and 2.4 m, with a mean of 0.8 ± 0.5 m. The average lateral-to-vertical ratio compiled at specific sites is ˜6:1. Summing displacements across subparallel, overlapping rupture traces implies a maximum of 7-11 m and net average of 4.4 ± 1.5 m, corresponding to a geologic Mw ˜7.5 for the 1872 event. We attribute progressively higher-offset lateral COPD peaks at 7.1 ± 2.0 m, 12.8 ± 1.5 m, and 16.6 ± 1.4 m to three earlier large surface ruptures. Evaluating cumulative displacements in context with previously dated landforms in Owens Valley suggests relatively modest rates of fault slip, averaging between ˜0.6 and 1.6 mm/yr (1σ) over the late Quaternary.

  20. Slip length crossover on a graphene surface

    SciTech Connect

    Liang, Zhi; Keblinski, Pawel

    2015-04-07

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

  1. Slip reactivation during the 2011 Tohoku earthquake: Dynamic rupture and ground motion simulations

    NASA Astrophysics Data System (ADS)

    Galvez, P.; Dalguer, L. A.

    2013-12-01

    The 2011 Mw9 Tohoku earthquake generated such as vast geophysical data that allows studying with an unprecedented resolution the spatial-temporal evolution of the rupture process of a mega thrust event. Joint source inversion of teleseismic, near-source strong motion and coseismic geodetic data , e.g [Lee et. al, 2011], reveal an evidence of slip reactivation process at areas of very large slip. The slip of snapshots of this source model shows that after about 40 seconds the big patch above to the hypocenter experienced an additional push of the slip (reactivation) towards the trench. These two possible repeating slip exhibited by source inversions can create two waveform envelops well distinguished in the ground motion pattern. In fact seismograms of the KiK-Net Japanese network contained this pattern. For instance a seismic station around Miyagi (MYGH10) has two main wavefronts separated between them by 40 seconds. A possible physical mechanism to explain the slip reactivation could be a thermal pressurization process occurring in the fault zone. In fact, Kanamori & Heaton, (2000) proposed that for large earthquakes frictional melting and fluid pressurization can play a key role of the rupture dynamics of giant earthquakes. If fluid exists in a fault zone, an increase of temperature can rise up the pore pressure enough to significantly reduce the frictional strength. Therefore, during a large earthquake the areas of big slip persuading strong thermal pressurization may result in a second drop of the frictional strength after reaching a certain value of slip. Following this principle, we adopt for slip weakening friction law and prescribe a certain maximum slip after which the friction coefficient linearly drops down again. The implementation of this friction law has been done in the latest unstructured spectral element code SPECFEM3D, Peter et. al. (2012). The non-planar subduction interface has been taken into account and place on it a big asperity patch inside

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

    NASA Astrophysics Data System (ADS)

    Ding, Xilun; Li, Kejia; Xu, Kun

    2012-09-01

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

  3. Periodic slow slip triggers megathrust zone earthquakes in northeastern Japan.

    PubMed

    Uchida, Naoki; Iinuma, Takeshi; Nadeau, Robert M; Bürgmann, Roland; Hino, Ryota

    2016-01-29

    Both aseismic and seismic slip accommodate relative motion across partially coupled plate-boundary faults. In northeastern Japan, aseismic slip occurs in the form of decelerating afterslip after large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust. Here we report on a previously unrecognized quasi-periodic slow-slip behavior that is widespread in the megathrust zone. The repeat intervals of the slow slip range from 1 to 6 years and often coincide with or precede clusters of large [magnitude (M) ≥ 5] earthquakes, including the 2011 M 9 Tohoku-oki earthquake. These results suggest that inherently periodic slow-slip events result in periodic stress perturbations and modulate the occurrence time of larger earthquakes. The periodicity in the slow-slip rate has the potential to help refine time-dependent earthquake forecasts. PMID:26823425

  4. Free energy of dislocations in a multi-slip geometry

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, M. G. D.

    2016-03-01

    The collective dynamics of dislocations is the underlying mechanism of plastic deformation in metallic crystals. Dislocation motion in metals generally occurs on multiple slip systems. The simultaneous activation of different slip systems plays a crucial role in crystal plasticity models. In this contribution, we study the energetic interactions between dislocations on different slip systems by deriving the free energy in a multi-slip geometry. In this, we restrict ourselves to straight and parallel edge dislocations. The obtained free energy has a long-range mean-field contribution, a statistical contribution and a many-body contribution. The many-body contribution is a local function of the total dislocation density on each slip system, and can therefore not be written in terms of the net dislocation density only. Moreover, this function is a strongly non-linear and non-convex function of the density on different slip systems, and hence the coupling between slip systems is of great importance.

  5. Spatiotemporal evolution of seismic and aseismic slip on the Longitudinal Valley Fault, Taiwan

    NASA Astrophysics Data System (ADS)

    Thomas, Marion Y.; Avouac, Jean-Philippe; Champenois, Johann; Lee, Jian-Cheng; Kuo, Long-Chen

    2014-06-01

    The Longitudinal Valley Fault (LVF) in eastern Taiwan is a high slip rate fault (about 5 cm/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 Global Positioning System(GPS) measurements, time 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 interferometric synthetic aperture radar (InSAR) measurements produced from a series of Advanced Land Observing Satellite images processed using a persistent scatterer technique. The combined data set 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. 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, and (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 southern section of LVF in the 0-26 km, seismogenic depth range, is actually aseismic

  6. Joint assembly

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  7. Detectability of slow slip beneath the seismogenic zone of strike-slip faults using borehole tiltmeters

    NASA Astrophysics Data System (ADS)

    Chery, J.

    2015-12-01

    During the last decades, geodetic tools like C-GPS allowed the detection of slow slip events associated with transient motion below the seismogenic zone. This new class of fault motion lead us to revise the standard version of the seismic cycle simply including coseismic, postseismic and interseismic phases. Most of these discoveries occurred on subduction margins in various places like Japan, Cascadia, Chile and Indonesia. By contrast, GPS and strainmeters have provided little evidence of slow slip beneath the seismogenic zone of large continental faults like the San Andreas fault or the North Anatolian fault. Because the detectability of such motions is mostly tributary from instrumental precision, we examine the theoretical capability of tiltmeter arrays for detecting horizontal motion of a buried vertical fault. We define the slipping part of the strike-slip fault like a buried rectangular patch submitted to horizontal motion. This motion provides horizontal and vertical surface deformation as a function of both patch geometry (length, width, depth) and motion amplitude. Using a dislocation buried at 15km depth, we compute the maximum motion and tilt as a function of seismic moment. Assuming yields of detectability of 1mm for GPS horizontal motion and 10 nrad for a tiltmeter, we show that small slip events could be better detected using high resolution and stability tiltmeters. We then examine how tiltmeters arrays could be used for such a purpose. In particular, we discuss how to deal with usual problems often plaguing tiltmeters data like instrumental drift, borehole coupling and hydrological strain.

  8. Slip of polydisperse polymers: Molecular weight distribution above and below the plane of slip

    NASA Astrophysics Data System (ADS)

    Sabzevari, Seyed Mostafa; Strandman, Satu; Wood-Adams, Paula Marie

    2015-04-01

    When strong slip occurs during the drag flow of highly entangled polybutadienes (PBD) in a sliding plate rheometer equipped with stainless steel parallel plates, a thin film of polymer debris remains on the substrate after the slip. This debris is assumed to be formed by the disentanglement process that occurs in strong slip at a distance of about one molecular size from the plate. In order to evaluate the composition of the debris we collected it with tetrahydrofuran and subjected it to gel permeation chromatography. It was found that the molecular weight distribution (MWD) of the debris is significantly different from that of the bulk. Moreover, in mixtures prepared from long and short PBDs with distinctly different molecular weight distributions, the MWD of the debris was found to be richer in low molecular weight components and leaner in the high molecular weight components compared to the bulk. This information is important since it reveals the compositional difference between the bulk and interfacial layer above and below the plane of slip. The difference in MWD is likely a consequence of the strong slip in which some of long chains are pulled away from the surface-adsorbed chains by the flow leaving a debris lean in the high molecular weight component.

  9. Simulation of Tremor and Slow Slip Earthquakes Along a Strike-Slip Fault

    NASA Astrophysics Data System (ADS)

    Payton, K. A.; Cochran, E. S.; Richards-Dinger, K. B.; Dieterich, J. H.; Harrington, R. M.; Kroll, K.

    2014-12-01

    We use an earthquake simulator to investigate the conditions that may result in tectonic tremor. Tremor comprises small seismic events often associated with slow slip earthquakes (SSEs) that were initially discovered in subduction zones, but have subsequently been observed along transform faults such as the San Andreas Fault. For this study, our primary region of interest is the Parkfield-Cholame segment of the San Andreas, which is located between the locked segment to the south and the creeping segment to the north. Due to Parkfield's unique history of successive earthquakes at quasi-regular intervals, deep borehole seismometers were installed in this region, enabling the discovery of low-amplitude tectonic tremor. To better understand the fault properties that result in SSEs and tremor, we utilize the earthquake simulator RSQSim to simulate multi-cycle SSEs and tremor along a planar strike-slip fault. RSQSim is a computationally efficient method that uses rate- and state- dependent friction to simulate a wide range of event sizes for long time histories of slip [Dieterich and Richards-Dinger, 2010; Richards-Dinger and Dieterich, 2012]. RSQSim has been previously used to investigate slow slip events in Cascadia [Colella et al., 2011; 2012]. Here, we examine a suite of parameters to understand the influence of normal stress, rate-and-state constants a and b, and slip speed as well as the distribution of tremor patches on tremor and SSE occurrence. We compare the simulation results to previous tremor observations.

  10. Modeling of rock friction 2. Simulation of preseismic slip

    USGS Publications Warehouse

    Dieterich, J.H.

    1979-01-01

    The constitutive relations developed in the companion paper are used to model detailed observations of preseismic slip and the onset of unstable slip in biaxial laboratory experiments. The simulations employ a deterministic plane strain finite element model to represent the interactions both within the sliding blocks and between the blocks and the loading apparatus. Both experiments and simulations show that preseismic slip is controlled by initial inhomogeneity of shear stress along the sliding surface relative to the frictional strength. As a consequence of the inhomogeneity, stable slip begins at a point on the surface and the area of slip slowly expands as the external loading increases. A previously proposed correlation between accelerating rates of stable slip and growth of the area of slip is supported by the simulations. In the simulations and in the experiments, unstable slip occurs shortly after a propagating slip event traverses the sliding surface and breaks out at the ends of the sample. In the model the breakout of stable slip causes a sudden acceleration of slip rates. Because of velocity dependency of the constitutive relationship for friction, the rapid acceleration of slip causes a decrease in frictional strength. Instability occurs when the frictional strength decreases with displacement at a rate that exceeds the intrinsic unloading characteristics of the sample and test machine. A simple slider-spring model that does not consider preseismic slip appears to approximate the transition adequately from stable sliding to unstable slip as a function of normal stress, machine stiffness, and surface roughness for small samples. However, for large samples and for natural faults the simulations suggest that the simple model may be inaccurate because it does not take into account potentially large preseismic displacements that will alter the friction parameters prior to instability. Copyright ?? 1979 by the American Geophysical Union.

  11. Slow Slip Events on a 760 mm Long Granite Sample

    NASA Astrophysics Data System (ADS)

    Mclaskey, G.; Yamashita, F.

    2015-12-01

    We describe slow slip events and dynamic rupture events generated on a newly constructed large-scale biaxial friction apparatus at Cornell University that provide insights into the mechanisms of aseismic and seismic slip. We find that, under nominally similar experimental conditions, the 760 mm long granite sample sometimes slips in dynamic stick-slip events and sometimes relieves accumulated shear stress through slow slip events. To provide insights into this curious behavior and the underlying mechanisms, fault slip and shear stress are each measured at 8 locations along the 760 mm long fault. This allows us to map slow slip fronts and the nucleation and propagation of dynamic fault rupture. The granite sample is also instrumented with an array of piezoelectric sensors that are the laboratory equivalent of a seismic network. When the sample is loaded relatively slowly, at 0.03 MPa/s, slow slip occurs on large sections of the fault and the slow slipping region soon expands to the sample boundary. In this case, stress is released in a slow slip event with peak slip velocities < 2 mm/s. Alternatively, when one end of the sample is loaded rapidly (4 MPa/s), or the sample is allowed to heal in stationary contact for a few minutes, slow slip initiates near the load point and accelerates to slip velocities exceeding 200 mm/s before the slow slipping region expands all the way to the sample boundary. This produces a dynamic slip event (stick-slip). The dynamic slip events radiate seismic waves equivalent to a M = -2.5 earthquake. In contrast, the laboratory-generated slow slip events are predominantly aseismic and produce only bursts of tiny and discrete seismic events (M = -6) reminiscent of swarms of microseismicity. The experiments illustrate how a single fault can slide slowly and aseismically or rapidly and dynamically depending on stress state and loading conditions. We compare the behavior observed on this Cornell apparatus to the behavior of other large

  12. Detailed history of slip along the Sunda mega-thrust

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    We undertook a reconstruction of more than 200 years of deformation on the Sunda mega-thrust using the history of vertical displacement recorded in the stratigraphy of coral micro-atolls. This reconstruction gave an unprecedented opportunity to understand the distributions of slip on the recent series of great earthquakes and its relationship with coupling. We have seen with the recent earthquakes that, whilst the slip-coupling relationship may be complex and certainly depends on the pre-stress, the greatest slip generally occurs in areas of high coupling. We have also seen that the spatial distributions of the greatest slip reveals tessellation between earthquakes. Using Monte Carlo techniques, we compare ground deformation produced by different fractal slip distributions with micro-atoll coral data to estimate slip distributions for the 1797 and 1833 historical earthquakes. The resulting slip estimations have a more realistic spatial distribution and provide a better fit to the micro-atoll data than previously published solutions. Preliminary results seem to imply that the 1797 and 1833 ruptures reveal a level of complementarity, where the greatest values of slip tessellate with the greatest slip values observed in the two great earthquakes of 2007 and the earthquake of 2010. In addition, the spatial stacking of all slips from all available earthquake slip distributions reveals a strong correlation with the spatial distribution of the coupling. Discrepancies in the spatial slip-coupling correlation, although strongly influenced by the uncertainties of the slip distributions, and with the 1797 and 1833 earthquakes playing a stronger role, can still be used as a way to pin-point possible areas of slip deficit when compared with the spatial distribution of coupling. This seems to imply that correspondence between the slip probability in 1797 and 1833 and present-day earthquakes slip and coupling appears to show the same basic relationship indicating that the broad

  13. Model equations in rarefied gas dynamics: Viscous-slip and thermal-slip coefficients

    NASA Astrophysics Data System (ADS)

    Siewert, C. E.; Sharipov, Felix

    2002-12-01

    Various model equations are used to define the viscous-slip and the thermal-slip coefficients in rarefied gas dynamics. More specifically, the BGK model, the S model, the variable collision model and the CES model are used to establish the slip coefficients basic to Kramers' problem and the half-space problem of thermal creep. While the most general results are developed from use of the Maxwell boundary condition, results for the BGK model and the S model as defined by the Cercignani-Lampis boundary condition are also reported. An analytical discrete-ordinates method is used to establish the reported numerical results, and when available results from a numerical solution of the linearized Boltzmann equation are used as reference values. In addition to the numerical work based on model equations, the important issue of how to define meaningful ways (appropriate mean-free paths) to compare the results for the various models is discussed.

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

    NASA Astrophysics Data System (ADS)

    McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

    2014-05-01

    In the last decade a series of devastating earthquakes have between them killed more than three-quarters of a million people. None of the events were formally forecast and have been repeatedly referred to a seismological 'surprises'. Here we argue that while earthquakes within the wide swath of diffuse deformation comprising the Alpine-Himalayan belt pose a set of particularly difficult set of challenges, earthquakes which are driven by high strain-rates at plate boundaries and which have relatively short nominal recurrence times might be forecast if the data exists to perform long-term slip deficit modelling and stress reconstruction. We show that two instrumentally recorded event on the Sumatran margin in 2007 and 2010 occurred in regions of high slip deficit identified by reconstruction of slip in historical earthquakes in 1797 and 1833 under the Mentawai Islands using more than 200 years of geodetic data recorded in the stratigraphy of coral micro-atolls growing there. In the presentation we will describe the data and a new Bayesian-Monte Carlo slip reconstruction technique. The technique is based on the stochastic forward modelling of many slip distributions each using the same set of elastic Green's functions to estimate, by superposition of contributions from each fault cell, the vertical displacement at the coral locations resulting from each simulated event. Every solution, weighted by its goodness of fit to the data, is added to a stack whose final values contain an estimate of the most likely distribution of slip in the historical earthquakes. Further, we estimate the Kullback-Liebler divergence over the fault area providing a non-arbitrary assessment of the spatial distribution of information gain, identifying regions of low- and high- model confidence. We then model the long-term slip deficit on the megathrust assuming a zero of stress immediately after the 1652 Mentawai Islands earthquake. We use the resulting slip deficit field to compute the entire

  15. Quasi-static versus dynamic triggering of fault slip

    NASA Astrophysics Data System (ADS)

    Wu, W.

    2013-12-01

    The quasi-static triggering of fault slip has long been recognized as a mechanism of earthquakes. The dynamic triggering of fault slip is associated with earthquake aftershocks and man-made geological hazards, such as rock collapse in underground excavations and induced seismicity in geothermal productions. The objective of this study is to experimentally investigate the differences between quasi-static and dynamic triggering of fault slip. A direct-shear configuration (Fig. 1) is developed to simulate fault slip, which consists of an incident norite plate (1000 × 120 × 30 mm) and a transverse norite plate (500 × 80 × 30 mm). A quartz sand layer is sandwiched between the incident and transverse plates to simulate a granular fault zone. A servo-controlled quasi-static loading system induces the quasi-static triggering of fault slip, and a dynamic loading system containing two parallel compressed springs instantaneously launches a striker norite plate (100 × 120 × 30 mm) to induce an incident P-wave (a half-wavelength of 750 mm). The P-wave propagates in the incident plate and causes the dynamic triggering of fault slip. The dynamic triggering of fault slip is designed to be solely induced by the P-wave before wave reflection at the plate end. Both quasi-static and dynamic triggering induce non-uniform shear stress distribution along the fault zone. There is a shear stress at the trailing edge, which controls the fault slip, and a rebound stress at the leading edge, which is caused by a small moment. The fault slip is triggered when the maximum shear stress reaches a critical value at the trailing edge and is accompanied by shear stress drop. The quasi-static triggering of fault slip is unrecoverable and includes a main slip and a few short slips before and after the main slip. The dynamic triggering of fault slip can be partially recovered after the P-wave and consists of a few unrecovered slips. The duration of the dynamic triggering of fault slip is a few

  16. Earthquake scaling laws for rupture geometry and slip heterogeneity

    NASA Astrophysics Data System (ADS)

    Thingbaijam, Kiran K. S.; Mai, P. Martin; Goda, Katsuichiro

    2016-04-01

    We analyze an extensive compilation of finite-fault rupture models to investigate earthquake scaling of source geometry and slip heterogeneity to derive new relationships for seismic and tsunami hazard assessment. Our dataset comprises 158 earthquakes with a total of 316 rupture models selected from the SRCMOD database (http://equake-rc.info/srcmod). We find that fault-length does not saturate with earthquake magnitude, while fault-width reveals inhibited growth due to the finite seismogenic thickness. For strike-slip earthquakes, fault-length grows more rapidly with increasing magnitude compared to events of other faulting types. Interestingly, our derived relationship falls between the L-model and W-model end-members. In contrast, both reverse and normal dip-slip events are more consistent with self-similar scaling of fault-length. However, fault-width scaling relationships for large strike-slip and normal dip-slip events, occurring on steeply dipping faults (δ~90° for strike-slip faults, and δ~60° for normal faults), deviate from self-similarity. Although reverse dip-slip events in general show self-similar scaling, the restricted growth of down-dip fault extent (with upper limit of ~200 km) can be seen for mega-thrust subduction events (M~9.0). Despite this fact, for a given earthquake magnitude, subduction reverse dip-slip events occupy relatively larger rupture area, compared to shallow crustal events. In addition, we characterize slip heterogeneity in terms of its probability distribution and spatial correlation structure to develop a complete stochastic random-field characterization of earthquake slip. We find that truncated exponential law best describes the probability distribution of slip, with observable scale parameters determined by the average and maximum slip. Applying Box-Cox transformation to slip distributions (to create quasi-normal distributed data) supports cube-root transformation, which also implies distinctive non-Gaussian slip

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

    USGS Publications Warehouse

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

    2005-01-01

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

  18. Shearing along faults and stratigraphic joints controlled by land subsidence in the Valley of Queretaro, Mexico

    NASA Astrophysics Data System (ADS)

    Carreón-Freyre, D.; Cerca, M.; Ochoa-González, G.; Teatini, P.; Zuñiga, F. R.

    2016-05-01

    Slip of nearly vertical faults or horizontal stratigraphic joints has provoked the shearing of at least 16 well casings in a period of over 10 years in the Valley of Queretaro aquifer, Mexico. Evidence integrated from field observations, remote surface-deformation monitoring, in-situ monitoring, stratigraphic correlation, and numerical modeling indicate that groundwater depletion and land subsidence induce shearing. Two main factors conditioning the stress distribution and the location of sheared well casings have been identified: (1) slip on fault planes, and (2) slip on stratigraphic joints. Additionally, the distribution of piezometric gradients may be a factor that enhances shearing. Slip on faults can be generated either by the compaction of sedimentary units (passive faulting) or by slip of blocks delimited by pre-existing faults (reactivation). Major piezometric-level declines and the distribution of hydraulic gradients can also be associated with slip at stratigraphic joints. Faults and hydraulic contrasts in the heterogeneous rock sequence, along with groundwater extraction, influence the distribution of the gradients and delimit the compartments of groundwater in the aquifer. Analogue modeling allowed assessment of the distribution of stress-strain and displacements associated with the increase of the vertical stress. Fault-bounded aquifers in grabens are common in the central part of Mexico and the results obtained can be applied to other subsiding, structurally controlled aquifer systems elsewhere.

  19. Shearing along faults and stratigraphic joints controlled by land subsidence in the Valley of Queretaro, Mexico

    NASA Astrophysics Data System (ADS)

    Carreón-Freyre, D.; Cerca, M.; Ochoa-González, G.; Teatini, P.; Zuñiga, F. R.

    2016-03-01

    Slip of nearly vertical faults or horizontal stratigraphic joints has provoked the shearing of at least 16 well casings in a period of over 10 years in the Valley of Queretaro aquifer, Mexico. Evidence integrated from field observations, remote surface-deformation monitoring, in-situ monitoring, stratigraphic correlation, and numerical modeling indicate that groundwater depletion and land subsidence induce shearing. Two main factors conditioning the stress distribution and the location of sheared well casings have been identified: (1) slip on fault planes, and (2) slip on stratigraphic joints. Additionally, the distribution of piezometric gradients may be a factor that enhances shearing. Slip on faults can be generated either by the compaction of sedimentary units (passive faulting) or by slip of blocks delimited by pre-existing faults (reactivation). Major piezometric-level declines and the distribution of hydraulic gradients can also be associated with slip at stratigraphic joints. Faults and hydraulic contrasts in the heterogeneous rock sequence, along with groundwater extraction, influence the distribution of the gradients and delimit the compartments of groundwater in the aquifer. Analogue modeling allowed assessment of the distribution of stress-strain and displacements associated with the increase of the vertical stress. Fault-bounded aquifers in grabens are common in the central part of Mexico and the results obtained can be applied to other subsiding, structurally controlled aquifer systems elsewhere.

  20. Basal slip and mechanical anisotropy of biotite

    SciTech Connect

    Kronenberg, A.K. ); Kirby, S.H.; Pinkston, J. )

    1990-11-10

    The basal slip systems of biotite and their mechanical expressions have been investigated by shortening single crystals oriented to maximize and minimize shear stresses on (001). Samples loaded at 45{degree} to (001) exhibit gentle external rotations associated with dislocation glide. Samples shortened perpendicular to (001) show no evidence of nonbasal slip and fail by fracture over all conditions tested. The mechanical response of biotite shortened at 45{degree} to (001) is nearly perfectly elastic-plastic; stress-strain curves are characterized by a steep elastic slope, a sharply defined yield point, and continued deformation at low (mostly < 100 MPa), relatively constant stresses at strains >1%. Stresses measured beyond the yield point are insensitive to confining pressure over the range 200 to 500 MPa and exhibit weak dependencies upon strain rate and temperature. Assuming an exponential relationship between differential stress {sigma}{sub d} and strain rate {epsilon} = C exp({minus}Q/RT), the data collected over strain rates and temperatures of 10-7 to 10-4 s-1 and 20 to 400C, respectively, are best fit by an exponential constant {alpha} of 0.41 {plus minus} 0.08 MPa{minus}1 and an activation energy Q of 82 {plus minus} 13 kJ/mol. A power law fits the data equally well with n = 18 {plus minus} 4 and Q = 51 {plus minus} 9 kJ/mol. The strength of biotite shortened perpendicular to (001) exceeds that measured parallel to (001) and is pressure dependent. Application of the results to deformation within the continental crust suggests that biotite oriented favorably for slip is much weaker than most silicates over a wide range of geologic conditions. Its presence within foliated rocks and shear zones may limit locally the stresses that can be supported.

  1. Kalker's algorithm Fastsim solves tangential contact problems with slip-dependent friction and friction anisotropy

    NASA Astrophysics Data System (ADS)

    Piotrowski, J.

    2010-07-01

    This paper presents two extensions of Kalker's algorithm Fastsim of the simplified theory of rolling contact. The first extension is for solving tangential contact problems with the coefficient of friction depending on slip velocity. Two friction laws have been considered: with and without recuperation of the static friction. According to the tribological hypothesis for metallic bodies shear failure, the friction law without recuperation of static friction is more suitable for wheel and rail than the other one. Sample results present local quantities inside the contact area (division to slip and adhesion, traction) as well as global ones (creep forces as functions of creepages and rolling velocity). For the coefficient of friction diminishing with slip, the creep forces decay after reaching the maximum and they depend on the rolling velocity. The second extension is for solving tangential contact problems with friction anisotropy characterised by a convex set of the permissible tangential tractions. The effect of the anisotropy has been shown on examples of rolling without spin and in the presence of pure spin for the elliptical set. The friction anisotropy influences tangential tractions and creep forces. Sample results present local and global quantities. Both extensions have been described with the same language of formulation and they may be merged into one, joint algorithm.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  3. Inertial and stick-slip regimes of unstable adhesive tape peeling.

    PubMed

    Dalbe, Marie-Julie; Villey, Richard; Ciccotti, Matteo; Santucci, Stéphane; Cortet, Pierre-Philippe; Vanel, Loïc

    2016-05-18

    We present an experimental characterization of the detachment front unstable dynamics observed during the peeling of pressure sensitive adhesives. We use an experimental set-up specifically designed to control the peeling angle θ and the peeled tape length L, while peeling an adhesive tape from a flat substrate at a constant driving velocity V. High-speed imaging allows us to report the evolution of the period and amplitude of the front oscillations, as well as the relative durations of their fast and slow phases, as a function of the control parameters V, L and θ. Our study shows that, as the driving velocity or the peeling angle increases, the oscillations of the peeling front progressively evolve from genuine "stick-slip" oscillations, made of alternating long stick phases and very brief slip phases, to sinusoidal oscillations of amplitude twice the peeling velocity. We propose a model which, taking into account the peeling angle-dependent kinetic energy cost to accelerate and decelerate the peeled tape, explains the transition from the "stick-slip" to the "inertial" regime of the dynamical instability. Using independent direct measurements of the effective fracture energy of the adhesive-substrate joint, we show that our model quantitatively accounts for the two regimes of the unstable dynamics. PMID:27050487

  4. Slip stacking experiments at Fermilab main injector

    SciTech Connect

    Kiyomi Koba et al.

    2003-06-02

    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.

  5. Episodic Tremor and Slip: Cycles Within Cycles

    NASA Astrophysics Data System (ADS)

    Creager, K. C.; Wech, A.; Vidale, J. E.

    2009-12-01

    Episodic tremor and slip (ETS) events, each with geodetically determined moment magnitudes in the mid-6 range, repeat about every 15 months under the Olympic Peninsula/southern Vancouver Island region. We have automatically searched for non-volcanic tremor in all 5-minute time windows both during the past five ETS events and during the two inter-ETS periods from February, 2007 through April, 2008 and June 2008 through April 2009. Inter-ETS tremor was detected in 5000 windows, which overlap by 50%, so tremor was seen 2% of the time. The catalog of 5-minute tremor locations cluster in time and space into groups we call tremor swarms, revealing 50 inter-ETS tremor swarms. The number of hours of tremor per swarm ranged from about 1 to 68, totaling 374 hours. The inter-ETS tremor swarms generally locate along the downdip side of the major ETS events, and account for approximately 45% of the time that tremor has been detected during the last two entire ETS cycles. Many of the inter-ETS events are near-carbon copies in duration, spatial extent and propagation direction, as is seen for the larger 15-month-interval events. These 50 inter-ETS swarms plus two major ETS episodes follow a power law relationship such that the number of swarms, N, exceeding duration τ is given by N ˜ τ-0.7. If we assume that seismic moment is proportional to τ as proposed by Ide et al. [Nature, 2007], we find that the tremor swarms follow a standard Gutenberg-Richter logarithmic frequency-magnitude relation, N ˜ 10-bMw, with b = 1.0, which lies in the range for normal earthquake catalogs. Furthermore, the major ETS events fall on the curve defined by the inter-ETS swarms, suggesting that the inter-ETS swarms are just smaller versions of the major 15-month ETS events. Only the largest events coincide with geodetically observed slip, suggesting that current geodetic observations may be missing nearly half of the total slip. Finally, crude estimates of the spatial dimensions of tremor swarms L

  6. Slipped capital femoral epiphysis: what's new?

    PubMed

    Peck, Kathryn; Herrera-Soto, José

    2014-01-01

    Slipped capital femoral epiphysis (SCFE) is a common hip disorder among adolescents, whereby the epiphysis is displaced posteriorly and inferiorly to the metaphysis. Treatment modalities aim to stabilize the epiphysis, prevent further slippage, and avoid complications associated with long-term morbidity, such as osteonecrosis and chondrolysis. Controversy exists with SCFE regarding prophylactic fixation of the contralateral, painless, normal hip, the role of femoroacetabular impingement with SCFE, and whether in situ fixation is the best treatment method for SCFE. This article presents and discusses the latest diagnostic and treatment modalities for SCFE. PMID:24267209

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

    USGS Publications Warehouse

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

    2012-01-01

    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.

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

    PubMed

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

    2015-04-01

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

  9. Fault slip controlled by stress path and fluid pressurization rate

    NASA Astrophysics Data System (ADS)

    French, Melodie E.; Zhu, Wenlu; Banker, Jeremy

    2016-05-01

    The practice of injecting fluids into the crust is linked to regional increases in seismicity. Increasing fluid pressure along preexisting faults is believed to enhance seismicity rates by reducing the shear stress required for slip, but the processes that cause faults to slip under conditions of fluid pressurization are poorly constrained. We use experimental rock deformation to investigate the controls of fluid pressurization and pressurization rates on fault slip style. We show that pore fluid pressurization is less effective that mechanical changes in fault normal stress at initiating accelerated slip events. Fluid pressurization enhances the total slip, slip velocity, and shear stress drop of events initiated by mechanical changes in normal stress, and these parameters are correlated with pressurization rate, but not the magnitude of fluid pressure. This result is consistent with field-scale observations and indicates that processes active at the pore network scale affect induced seismicity.

  10. A diary study of action slips in healthy individuals.

    PubMed

    Jónsdóttir, María K; Adólfsdóttir, Steinunn; Cortez, Rúna Dögg; Gunnarsdóttir, María; Gústafsdóttir, Agústa Hlín

    2007-12-01

    Memory complaints following minor head injury or whiplash are common and often bear similarity to absent mindedness or action slips (Reason, 1979). We replicated Reason's study by asking 189 healthy volunteers to keep diaries of their action slips for a week. The mean number of slips was 6.4 (SD = 4.9). Perceived stress did not correlate with number of slips but there was a weak positive correlation between action slips and scores on a memory failures questionnaire. Memory diaries may be clinically useful when assessing individuals who worry about cognitive sequelae of minor injuries. Diaries clarify the nature of the complaints and may have therapeutic value by demonstrating that the memory slips are less frequent than estimated by the patients. PMID:17853144

  11. Cascadia tremor polarization evidence for plate interface slip

    NASA Astrophysics Data System (ADS)

    Wech, Aaron G.; Creager, Kenneth C.

    2007-11-01

    New seismic measurements of the repeated phenomenon of Episodic Tremor and Slip in northern Cascadia indicate identical source processes of tremor and slow slip. Predicted polarization directions of upgoing S-waves radiated from shear slip on the plate interface align with the relative motion between the Juan de Fuca and North American plates. Seismic observations from small-aperture array data on the Olympic Peninsula of the Cascadia subduction zone show uncharacteristically stable linear particle motion coincident with the passage of tremor sources beneath the array. The azimuth of this horizontal ground motion matches expected polarizations from slip on the plate interface. This finding suggests that Cascadia tremor is shear slip on the plate interface, implying that, as in Japan, geodetically observed slow slip and seismically observed tremor are manifestations of the same phenomenon.

  12. Subduction zone structures and slip behavior in megathrust

    NASA Astrophysics Data System (ADS)

    Kodaira, S.; Nakanishi, A.; Nakamura, Y.

    2014-12-01

    Earthquake, tsunami and geodetic data show that co-seismic slips of a large megathrust earthquakes do not uniformly propagate along a plate boundary. For example, a clear segmentation of slip zones of magnitude-8 class megathrust earthquakes are well recognized in the Nankai Trough. Moreover, a lateral variation of the slips are revealed even in one segment. In the Japan Trench, the most characteristic slip behavior of the 2011 Tohoku-oki earthquake is an extremely large slip reaching to the trench axis, but geodetic, tsunami or teleseismic show the slip was heterogeneous near the trench. In order to examine whether those complex slip distributions are attributed by any distinct structural factor, we have been carried out active-source seismic surveys in the subduction seismogenic. In the Nankai Trough, large-scale subducted seamounts, ridges and doming structure intruded in an overriding accretion wedge are imaged. Comparing co-seismic slip distribution of the 1944 Tonankai and the 1946 Nankai earthquakes with the seismic images, we concluded that those structures are key factors to control the slip distributions. In the central part of the Japan Trench area, we fund a rough basement geometry is overprinted on the horst-and-graben structure. Those complex geometry of basement cause a strong lateral variation of the thickness of subducting pelagic/hemi-pelagic sediment. Many geological studies suggest that properties of the plate-boundary sediment attribute the large slip near the trench. We therefore plan to acquire additional high-resolution seismic data in the entire Japan Trench in order to examine a role of incoming sediment on the large slip to the trench axis. In this presentation we present an overview of the structural factors controlling slips in megathrust earthquakes, including new data acquired in the Nankai Trough and Japan Trench.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  15. Frictional slip of granite at hydrothermal conditions

    USGS Publications Warehouse

    Blanpied, M.L.; Lockner, D.A.; Byerlee, J.D.

    1995-01-01

    To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, laboratory granite faults containing a layer of granite powder (simulated gouge) were slid. The mechanical results define two regimes. The first regime includes dry granite up to at least 845?? and wet granite below 250??C. In this regime the coefficient of friction is high (?? = 0.7 to 0.8) and depends only modestly on temperature, slip rate, and PH2O. The second regime includes wet granite above ~350??C. In this regime friction decreases considerably with increasing temperature (temperature weakening) and with decreasing slip rate (velocity strengthening). These regimes correspond well to those identified in sliding tests on ultrafine quartz. The results highlight the importance of fluid-assisted deformation processes active in faults at depth and the need for laboratory studies on the roles of additional factors such as fluid chemistry, large displacements, higher concentrations of phyllosilicates, and time-dependent fault healing. -from Authors

  16. Manifestations of Strike-Slip Faulting on Ganymede

    NASA Technical Reports Server (NTRS)

    DeRemer, Lindsay C.; Pappalardo, Robert T.

    2003-01-01

    Voyager images of Ganymede suggested that strike-slip faulting may have taken place [1, 2], but the role of this process in shaping grooved terrain was uncertain. In Galileo high-resolution images of Ganymede's surface, we recognize three signature features of strike-slip faulting: (1) en echelon structures, (2) strike-slip duplexes, and (3) offset preexisting features. We have undertaken a study to recognize and map these features, and identify any morphological progressions of strike-slip features. This will allow a better understanding of the structural history of Ganymede, and the formation and evolution of grooved terrain.

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

    USGS Publications Warehouse

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

    1989-01-01

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

  18. Strong dynamical effects during stick-slip adhesive peeling

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  19. Micromechanics of slip bands on a free surface

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    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.

  20. Compilation of Fault Slip Rates in Western United States

    NASA Astrophysics Data System (ADS)

    Heller, S. J.; McCaffrey, R.

    2009-12-01

    The faults that fall along the North American and Pacific plate boundary are continually changing. Through observing the way that faults have changed over geological history we may be able to get a better idea of how they may affect us in the future. To help this effort, this compilation provides sited work of prehistoric faulting events which may be used to compare to current geodetic (GPS) slip rates to obtain a better idea as to how faults have changed over history. A compilation of slip rates may also be useful when attempting to compare new methods of finding current slip rates compared to past methods and compare the accuracy of the slip rates that were found. The data were taken from published papers and abstracts that describe slip rates from this area. All data in this compilation are based on field investigations, mostly describing paleoseismic studies or offsets of geological features and their ages. Ages of these slip rates are found between the ages of 3.8 million years ago and 1857 AD. A compilation of slip rate data will be used for modeling purposes and to examine how slip rates have changed over thousands of years. This provides an up to date list of slip rates that previous compilations may have not provided. This work was supported by a NASA/NY Space Grant.

  1. Slip to the Trench for Great Subduction Earthquakes

    NASA Astrophysics Data System (ADS)

    Mori, J. J.

    2015-12-01

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

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

    PubMed

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

    2014-01-15

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

  3. How is a stick slip rupture initiated?

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    We investigated the initiation process of stick slip events that occurred during large scale rock friction experiments conducted on the large scale shaking table at NIED (Fukuyama et al., 2012, AGU Fall meeting). We used a pair of Indian gabbro rock samples stacked vertically and applied normal and shear forces. The sliding area between the samples is 1.5m in length and 0.1m in width. We conducted a sequence of experiments using the same rock sample, and before each experiment we removed gouge particles created during the previous experiment by a brush and a cleaner. Here, we show the experiments under constant slip velocity of 0.1mm/s with constant normal stress of 2.7MPa (LB04-003) or 6.7MPa (LB04-005); the final displacement reached 0.04m. We used 44 acoustic sensors (PZT, vertical mode, 0.5MHz resonance frequency), 32 2-comp strain gouges (SGs) for shear strain and 16 1-comp SGs for normal strain measurements, with 48 0.5MHz dynamic SG amplifiers. We also used a 2MN load cell for shear force measurement and three 0.4MN load cells for vertical forces. Data are recorded continuously at an interval of 10MHz for PZT and 1MHz for other sensors. Just after the shear force applied, many stick slip events (SEs) occurred at an interval of a few seconds. By looking carefully at the PZT and SG array data during an SE, we found that one SE consists of many micro stick slip events (MSEs), which can be grouped into two (the former and the latter). These two groups correspond to the acceleration and deceleration stage of the SE. In LB04-005 (6.7MPa normal stress), a clear nucleation phase can be detected that initiated at a narrow area, propagate slowly (~20m/s) and accelerated. Then, a seismic rupture started to propagate at a velocity of ~3km/s (subshear) or ~6.5km/s (supershear). Detailed features are shown in Mizoguchi et al. (this meeting). It should be noted that this seismic rupture initiated at a narrow area inside the nucleation zone and sometimes after a certain

  4. Generic element formulation for modelling bolted lap joints

    NASA Astrophysics Data System (ADS)

    Ahmadian, Hamid; Jalali, Hassan

    2007-07-01

    Joints have significant effects on the dynamic response of the assembled structures due to existence of two non-linear mechanisms in their interface, namely slipping and slapping. These mechanisms affect the structural response by adding considerable damping into the structure and lowering the natural frequencies due to the stiffness softening. Neglecting these effects in modelling of joints produces errors in predictions of the structure responses. In this paper, a non-linear generic element formulation is developed for modelling bolted lap joints. The generic element is formed by satisfying all conditions that are known for a joint interface and hence providing a non-linear parametric formulation for the families of allowable joint models. Dynamic response of the developed model for the assembled structure including the generic joint interface element is obtained using the incremental harmonic balance (IHB) method. The generic parameters of the joint are identified by minimising the difference between the model response obtained from IHB method and the observed behaviour of the structure. The procedure is demonstrated by modelling an actual structure containing a single lap bolted joint in the middle. The frequency responses of the structure around the first two resonance frequencies are measured by exciting the structure using a sinusoidal force at each individual frequency. The measured responses are compared with the predictions of the model containing a parametric generic joint element. The parameters of the joint interface model are successfully identified by minimising the difference between the measured responses and the model predictions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. Parametric Study of Smooth Joint Parameters on the Shear Behaviour of Rock Joints

    NASA Astrophysics Data System (ADS)

    Bahaaddini, M.; Hagan, P. C.; Mitra, R.; Hebblewhite, B. K.

    2015-05-01

    This paper aims to study the shear behaviour of rock joints in a direct shear test using the particle flow code PFC2D. In this numerical approach, the intact rock is simulated by densely packed circular particles that are bonded together at their contact points; joint surfaces can be explicitly simulated using the modified smooth joint (SJ) model. In the modified SJ model for simulation of direct shear test, micro-scale slip surfaces (smooth joint contacts) are applied at contacts between the particles of the upper and lower blocks of the shear box and the mechanical behaviour of the joints is controlled by the micro-scale properties of the smooth joint contacts. Two joint profiles of standard JRC 10-12 and a sawtooth triangular joint with a base angle of 15° were selected for testing. The results of direct shear tests under different normal stresses on these two profiles show that for the sawtooth triangular joints under a normal stress of 1 MPa, the shearing mechanism is purely sliding, and for the JRC 10-12 profile under a normal stress of 4 MPa, the shearing of first-order asperities controls the shearing mechanism. A parametric study of the micro-properties of the smooth joints under these two different shearing mechanisms was undertaken. The results of this study show that the SJ normal stiffness and the SJ shear stiffness have insubstantial effect on the peak shear strength in sliding mode, but that the SJ normal stiffness has a significant effect on the dilation rate in both sliding and shearing modes.

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

    USGS Publications Warehouse

    Rymer, M.J.; Tinsley, J. C., III; 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

    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.

  9. Comparison of Joint Modeling Approaches Including Eulerian Sliding Interfaces

    SciTech Connect

    Lomov, I; Antoun, T; Vorobiev, O

    2009-12-16

    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

  10. Slip Line Field Applied To Deep Drawing

    SciTech Connect

    Miguel, V.; Coello, J.; Calatayud, A.; Martinez, A.; Benet, J

    2007-05-17

    Slip Line Field is a numerical method applied for modelling plane-strain processes. This method has been successfully checked properly for sheet drawing. Flange deformation in deep drawing is considered without change in thickness. A drawing mechanical test has been developed in order to reproduce the flange stresses state in sheet strips with the rolling direction selected. The fundamentals of this test, and some experimental results obtained from it, have been presented previously in different Congresses. In this work, an algorithm based on SLF has been implemented and theoretical results evaluated for different conditions. The algorithm have been applied to a mild DDQ steel and to a DDQ AISI 304 stainless steel. Theoretical and experimental results are compared. A good concordance in them has been found out under some conditions. One of the most important aspects is that it must not be considered tensile material properties but a modified behavior under multiaxial conditions.

  11. Rolling and slipping motion of Euler's disk

    NASA Astrophysics Data System (ADS)

    Caps, H.; Dorbolo, S.; Ponte, S.; Croisier, H.; Vandewalle, N.

    2004-05-01

    We present an experimental study of the motion of a circular disk spun onto a table. With the help of a high speed video system, the temporal evolution of (i) the inclination angle α , (ii) the angular velocity ω , and (iii) the precession rate Ω are studied. The influence of the mass of the disk as well as the friction between the disk and the supporting surface are considered. Both inclination angle and angular velocity are observed to decrease according to a power law. We also show that the precession rate diverges as the motion stops. Measurements are performed very near the collapse as well as on long range times. Times to collapse have been also measured. Results are compared with previous theoretical and experimental works. The major source of energy dissipation is found to be the slipping of the disk on the plane.

  12. Oscillatory Magnetogasdynamic Slip Flow in a Microchannel

    NASA Astrophysics Data System (ADS)

    Agarwal, Ramesh

    2009-11-01

    The problem of pressure driven Magnetogasdynamic (MGD) slip flow with small rarefaction through a long micro-channel is considered. The flow is driven by steady or oscillatory pressure gradient. The study of MGD flows in microchannels is of great interest since they occur in magnetic thin films and other electromagnetic micro-scale devices. In obtaining the micro-fluidic solutions in the presence of a magnetic field, some additional physical, mathematical and numerical issues need to be considered. These issues deal with the scaling laws for micro-scale MHD flows and the relevant parameters such as Mach number, Reynolds number, Hartmann number, magnetic Reynolds number, and Knudsen number. For planar constant area micro-channel, it is possible to obtain the analytical solutions for both steady and oscillatory pressure driven flows. As physically expected, the higher value of the magnetic field (higher Hartmann number) flattens the velocity profile in the channel.

  13. Instantaneous Slip Length in Superhydrophobic Microchannels

    NASA Astrophysics Data System (ADS)

    Hemeda, Ahmed; Tafreshi, Hooman; VCU Team

    2015-11-01

    Superhydrophobic (SHP) surfaces can be used to reduce the skin-friction drag in a microchannel. This favorable effect, however, can deteriorate over time if the surface geometry is not designed properly. This study presents a mathematical means for studying the time-dependent drag-reduction in a microchannel enhanced with SHP grooves of varying geometries. The performance of an SHP groove is found to be dependent on the interplay between the effects of the apparent contact angle of the air-water interface and the initial volume of the groove. The instantaneous slip length is calculated by solving the Navier-Stokes equations for flow in a microchannel with such SHP grooves, and the results are compared with the studies in the literature. National Science Foundation CMMI 1029924 and CBET 1402655.

  14. Rover Slip Validation and Prediction Algorithm

    NASA Technical Reports Server (NTRS)

    Yen, Jeng

    2009-01-01

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

  15. Regulating the working properties of porcelain slip

    SciTech Connect

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

    1986-05-01

    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.

  16. Slip distribution of the 2003 Boumerdes-Zemmouri earthquake, Algeria, from teleseismic, GPS, and coastal uplift data

    NASA Astrophysics Data System (ADS)

    Delouis, B.; Vallée, M.; Meghraoui, M.; Calais, E.; Maouche, S.; Lammali, K.; Mahsas, A.; Briole, P.; Benhamouda, F.; Yelles, K.

    2004-09-01

    Using a joint inversion of seismological waveforms and ground displacement observations, we estimate several parameters of the fault geometry and rupture process of the Mw = 6.9 May 21, 2003 Boumerdes-Zemmouri earthquake. The relocated epicenter is considered as a known parameter. Total rupture length, rupture duration, and maximum slip are 55 km (from 3.4°E to 4.0°E), 12 s, and 3 m. The modeled south dipping reverse fault, oriented ENE-WSW outcrops a few km offshore which is consistent with the absence of observed surface rupture inland. Two shallow and relatively localized slip zones are found, on both sides of the hypocenter. To the SW, between Boumerdes and Zemmouri, slip is concentrated between 11 and 2 km depth. To the NE, between Zemmouri and Dellys, slip is concentrated between 6 km depth and the sea floor. Various resolution tests indicate that our model is well constrained by the available data, and help understanding which data constrains each parameter of the model.

  17. Slip flow through colloidal crystals of varying particle diameter.

    PubMed

    Rogers, Benjamin J; Wirth, Mary J

    2013-01-22

    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

  18. Frictional weakening and slip complexity in earthquake faults

    NASA Astrophysics Data System (ADS)

    Shaw, Bruce E.

    1995-09-01

    Previous work has shown that velocity-weakening friction produces slip complexity in simple dynamical models of earthquake faults (Carlson and Langer, 1989). Here I show that a different type of dynamical instability, caused by slip-weakening friction, also produces slip complexity. The deterministically chaotic slip complexity produced by slip-weakening friction in a simple one dimensional model is studied and the scaling of the distribution of sizes of events with the parameters in the model examined. In addition, a possible physical origin of frictional weakening is examined, through a very simplified mathematical representation of a physical process proposed by Sibson (1973), whereby frictional heating causes an increase in pore fluid temperature and pressure, thereby reducing the effective normal stress and friction. The two different types of frictional weakening are derived from two opposing limits, with slip weakening occurring when the dissipation of heating is slow compared to the rupture timescale, as Lachenbruch (1980) has shown, while velocity weakening is shown to occur when the dissipation is fast compared to the rupture timescale. Since both end-member cases of frictional weakening are seen to produce slip complexity, slip complexity is argued to be a generic feature of frictional weakening and elastodynamics on a fault.

  19. Automatic editing the cycle slips in GPS - observables.

    NASA Astrophysics Data System (ADS)

    Xiong, Yongqing

    Current methods of detecting and repairing cycle slips in the preprocessing of GPS data are concluded. Based on these methods, the author introduces a program named AUTCLN, which can repair cycle slips automatically, and is significantly more effective than other processing methods in reducing the amount of manual editing required.

  20. Role of Slip Mode on Stress Corrosion Cracking Behavior

    NASA Astrophysics Data System (ADS)

    Vasudevan, A. K.; Sadananda, K.

    2011-02-01

    In this article, we examine the effect of aging treatment and the role of planarity of slip on stress corrosion cracking (SCC) behavior in precipitation-hardened alloys. With aging, the slip mode can change from a planar slip in the underage (UA) to a wavy slip in the overage (OA) region. This, in turn, results in sharpening the crack tip in the UA compared to blunting in the OA condition. We propose that the planar slip enhances the stress concentration effects by making the alloys more susceptible to SCC. In addition, the planarity of slip enhances plateau velocities, reduces thresholds for SCC, and reduces component life. We show that the effect of slip planarity is somewhat similar to the effects of mechanically induced stress concentrations such as due to the presence of sharp notches. Aging treatment also causes variations in the matrix and grain boundary (GB) microstructures, along with typical mechanical and SCC properties. These properties include yield stress, work hardening rate, fracture toughness K IC , thresholds K Iscc, and steady-state plateau velocity ( da/ dt). The SCC data for a wide range of ductile alloys including 7050, 7075, 5083, 5456 Al, MAR M steels, and solid solution copper-base alloys are collected from the literature. Our assertion is that slip mode and the resulting stress concentration are important factors in SCC behavior. This is further supported by similar observations in many other systems including some steels, Al alloys, and Cu alloys.

  1. Slip Flow through Colloidal Crystals of Varying Particle Diameter

    PubMed Central

    Rogers, Benjamin J.; Wirth, Mary J.

    2012-01-01

    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. PMID:23237590

  2. Slip, trip, and fall injuries among nursing care facility workers.

    PubMed

    Bell, Jennifer L; Collins, James W; Tiesman, Hope M; Ridenour, Marilyn; Konda, Srinivas; Wolf, Laurie; Evanoff, Bradley

    2013-04-01

    The objective of this research was to describe the slip, trip, and fall injury experience and trends in a population of nursing home workers, identify risk factors for slip, trip, and fall injuries, and develop prevention strategies for slip, trip, and fall hazards. Workers' compensation injury claims data and payroll data from 1996 through 2003 were obtained from six nursing homes and used to calculate injury incidence rates. Narrative information was used to describe details of slip, trip, and fall events. A total of 86 slip, trip, and fall-related workers' compensation claims were filed during the 8-year period. Slip, trip, and fall claim rates showed a nonsignificant increase during the 8-year period. Most slips, trips, and falls were attributed to hazards that can be mitigated (e.g., water on the floor or loose cords in a walkway). Nursing home workers experience more slip, trip, and fall-related injury claims than workers in other industries. Preventive programs should be implemented and evaluated in this industry. PMID:23521142

  3. A Transformational Approach to Slip-Slide Factoring

    ERIC Educational Resources Information Center

    Steckroth, Jeffrey

    2015-01-01

    In this "Delving Deeper" article, the author introduces the slip-slide method for solving Algebra 1 mathematics problems. This article compares the traditional method approach of trial and error to the slip-slide method of factoring. Tools that used to be taken for granted now make it possible to investigate relationships visually,…

  4. Tremor during ice-stream stick slip

    NASA Astrophysics Data System (ADS)

    Lipovsky, B. P.; Dunham, E. M.

    2016-02-01

    During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice-bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spectral peaks at integer multiples of the recurrence frequency ˜ 10-20 Hz. We conduct numerical simulations of the tremor episodes that include the balance of forces acting on the fault, the evolution of rate- and state-dependent fault friction, and wave propagation from the fault patch to a seismometer located on the ice. The ice slides as an elastic block loaded by the push of the upstream ice, and so the simulated basal fault patch experiences a loading velocity equal to the velocity observed by GPS receivers on the surface of the WIP. By matching synthetic seismograms to observed seismograms, we infer fault patch area ˜ 10 m2, bed shear modulus ˜ 20 MPa, effective pressure ˜ 10 kPa, and frictional state evolution distance ˜ 1 μm. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. The amplitude of tremor (recorded by seismometers on the ice surface) is greater during the double wait time events that follow skipped events. The physical mechanism responsible for these elevated amplitudes may provide a window into near-future subglacial conditions and the processes that occur during ice-stream stagnation.

  5. Joint instability and osteoarthritis.

    PubMed

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

    2015-01-01

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

  6. Joint x-ray

    MedlinePlus

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

  7. Joint Instability and Osteoarthritis

    PubMed Central

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

    2015-01-01

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

  8. Thermal slip for liquids at rough solid surfaces

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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).

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

    PubMed

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

    2014-12-12

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

  10. Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  11. Learning and Prediction of Slip from Visual Information

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  12. Proposed Cavity for Reduced Slip-Stacking Loss

    SciTech Connect

    Eldred, J.; Zwaska, R.

    2015-06-01

    This paper employs a novel dynamical mechanism to improve the performance of slip-stacking. Slip-stacking in an accumulation technique used at Fermilab since 2004 which nearly double the proton intensity. During slip-stacking, the Recycler or the Main Injector stores two particles beams that spatially overlap but have different momenta. The two particle beams are longitudinally focused by two 53 MHz 100 kV RF cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV RF cavity, with a frequency at the double the average of the upper and lower main RF frequencies. In simulation, we find the proposed RF cavity significantly enhances the stable bucket area and reduces slip-stacking losses under reasonable injection scenarios. We quantify and map the stability of the parameter space for any accelerator implementing slip-stacking with the addition of a harmonic RF cavity.

  13. Studies on the spermatogenic sulfogalactolipid binding protein SLIP 1

    SciTech Connect

    Lingwood, C.; Nutikka, A. )

    1991-02-01

    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.

  14. Nailing down the slip rate of the Altyn Tagh fault

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  15. Stochastic stick-slip nanoscale friction on oxide surfaces.

    PubMed

    Craciun, A D; Gallani, J L; Rastei, M V

    2016-02-01

    The force needed to move a nanometer-scale contact on various oxide surfaces has been studied using an atomic force microscope and theoretical modeling. Force-distance traces unveil a stick-slip movement with erratic slip events separated by several nanometers. A linear scaling of friction force with normal load along with low pull-off forces reveals dispersive adhesive interactions at the interface. We model our findings by considering a variable Lennard-Jones-like interaction potential, which accounts for slip-induced variation of the effective contact area. The model explains the formation and fluctuation of stick-slip phases and provides guidelines for predicting transitions from stick-slip to continuous sliding on oxide surfaces. PMID:26751769

  16. Seismicity triggered by fluid injection-induced aseismic slip

    NASA Astrophysics Data System (ADS)

    Guglielmi, Yves; Cappa, Frédéric; Avouac, Jean-Philippe; Henry, Pierre; Elsworth, Derek

    2015-06-01

    Anthropogenic fluid injections are known to induce earthquakes. The mechanisms involved are poorly understood, and our ability to assess the seismic hazard associated with geothermal energy or unconventional hydrocarbon production remains limited. We directly measure fault slip and seismicity induced by fluid injection into a natural fault. We observe highly dilatant and slow [~4 micrometers per second (μm/s)] aseismic slip associated with a 20-fold increase of permeability, which transitions to faster slip (~10 μm/s) associated with reduced dilatancy and micro-earthquakes. Most aseismic slip occurs within the fluid-pressurized zone and obeys a rate-strengthening friction law μ=0.67+0.045ln(vv0) with v0 = 0.1 μm/s. Fluid injection primarily triggers aseismic slip in this experiment, with micro-earthquakes being an indirect effect mediated by aseismic creep.

  17. The Slip Hypothesis: Tactile Perception and its Neuronal Bases.

    PubMed

    Schwarz, Cornelius

    2016-07-01

    The slip hypothesis of epicritic tactile perception interprets actively moving sensor and touched objects as a frictional system, known to lead to jerky relative movements called 'slips'. These slips depend on object geometry, forces, material properties, and environmental factors, and, thus, have the power to incorporate coding of the perceptual target, as well as perceptual strategies (sensor movement). Tactile information as transferred by slips will be encoded discontinuously in space and time, because slips sometimes engage only parts of the touching surfaces and appear as discrete and rare events in time. This discontinuity may have forced tactile systems of vibrissae and fingertips to evolve special ways to convert touch signals to a tactile percept. PMID:27311927

  18. Estimation of slip parameters of a slip zone in the shallow portion of an accretionary prism

    NASA Astrophysics Data System (ADS)

    Hamada, Y.; Hirono, T.; Ishikawa, T.

    2010-12-01

    To evaluate the widely accepted scenario that a megasplay fault branching from a subduction boundary megathrust can contribute to the generation of devastating tsunamis, we investigated a major reverse fault in the Emi Group, Boso Peninsula, Japan, corresponding to the shallow portion of a thrust in an accretionary prism. We examined the rocks of the slip zone and the surrounding host rocks microscopically, and analyzed their trace elements and isotopes. On the basis of the fluid-mobile trace-element spectrum, which is sensitive to fluid-rock interaction at high temperatures, we estimated the paleo-thermal history of the slip zone. We discovered that the slip zone experienced frictional heating of >350 °C caused by high-velocity sliding. By numerical analysis of the frictional heating, we also estimated a large displacement of several meters along the fault at the shallow depth of approximately 1-2 km below the seafloor. Our results support the hypothesis that the megasplay fault plays an important role in the generation of huge tsunamis during subduction boundary earthquakes.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    '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.

  20. Local tsunamis and distributed slip at the source

    USGS Publications Warehouse

    Geist, E.L.; Dmowska, R.

    1999-01-01

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

  1. Constraining fault constitutive behavior with slip and stress heterogeneity

    USGS Publications Warehouse

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

    2008-01-01

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

  2. Spacesuit mobility knee joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1979-01-01

    Pressure suit mobility joints are for use in interconnecting adjacent segments of an hermetically sealed spacesuit in which low torques, low leakage and a high degree of reliability are required. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics and includes linkages which restrain the joint from longitudinal distension and includes a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli. 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.

  3. Spacesuit mobility joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1978-01-01

    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.

  4. Mechanics of slip and fracture along small faults and simple strike-slip fault zones in granitic rock

    NASA Astrophysics Data System (ADS)

    Martel, Stephen J.; Pollard, David D.

    1989-07-01

    We exploit quasi-static fracture mechanics models for slip along pre-existing faults to account for the fracture structure observed along small exhumed faults and small segmented fault zones in the Mount Abbot quadrangle of California and to estimate stress drop and shear fracture energy from geological field measurements. Along small strike-slip faults, cracks that splay from the faults are common only near fault ends. In contrast, many cracks splay from the boundary faults at the edges of a simple fault zone. Except near segment ends, the cracks preferentially splay into a zone. We infer that shear displacement discontinuities (slip patches) along a small fault propagated to near the fault ends and caused fracturing there. Based on elastic stress analyses, we suggest that slip on one boundary fault triggered slip on the adjacent boundary fault, and that the subsequent interaction of the slip patches preferentially led to the generation of fractures that splayed into the zones away from segment ends and out of the zones near segment ends. We estimate the average stress drops for slip events along the fault zones as ˜1 MPa and the shear fracture energy release rate during slip as 5 × 102 - 2 × 104 J/m2. This estimate is similar to those obtained from shear fracture of laboratory samples, but orders of magnitude less than those for large fault zones. These results suggest that the shear fracture energy release rate increases as the structural complexity of fault zones increases.

  5. Investigation of crystallographic slip in polycrystalline Fe{sub 3}Al using slip trace measurement and microtexture determination

    SciTech Connect

    Raabe, D.; Keichel, J.; Gottstein, G.

    1997-07-01

    An intermetallic Fe{sub 72}Al{sub 28} alloy (doped with Cr, Zr, Mo, and C) with an imperfectly ordered B2 crystal structure was rolled at 830--860 K to {epsilon} = 20%. To investigate crystallographic slip an etching technique was developed which allowed slip traces to be determined in grain interiors rather than at the sample surface. To derive the prevalent glide systems both the slip traces and the corresponding orientations were determined in grain scale. Three types of slip systems were identified, namely {l_brace}110{r_brace}<111>, {l_brace}112{r_brace}<111>, and {l_brace}123{r_brace}<111>. However, the slip traces produced by {l_brace}123{r_brace}<111> systems appeared wavy and were interpreted in terms of macroscopic or effective rather than crystallographic slip. The critical resolved shear stress ratio of the slip systems involved was fitted from experiment using a Relaxed Constraints Taylor model. The best correspondence between predicted and experimentally observed slip systems was attained for a critical resolver shear stress ratio of {tau}{sub {l_brace}110{r_brace}}/{tau}{sub {l_brace}112{r_brace}} = 1.05/1.0.

  6. Joint Inversion of 1-Hz GPS Data and Strong Motion Records for the Rupture Process of the 2008 Iwate-Miyagi Nairiku Earthquake: Objectively Determining Relative Weighting

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Kato, T.; Wang, Y.

    2015-12-01

    The spatiotemporal fault slip history of the 2008 Iwate-Miyagi Nairiku earthquake, Japan, is obtained by the joint inversion of 1-Hz GPS waveforms and near-field strong motion records. 1-Hz GPS data from GEONET is processed by GAMIT/GLOBK and then a low-pass filter of 0.05 Hz is applied. The ground surface strong motion records from stations of K-NET and Kik-Net are band-pass filtered for the range of 0.05 ~ 0.3 Hz and integrated once to obtain velocity. The joint inversion exploits a broader frequency band for near-field ground motions, which provides excellent constraints for both the detailed slip history and slip distribution. A fully Bayesian inversion method is performed to simultaneously and objectively determine the rupture model, the unknown relative weighting of multiple data sets and the unknown smoothing hyperparameters. The preferred rupture model is stable for different choices of velocity structure model and station distribution, with maximum slip of ~ 8.0 m and seismic moment of 2.9 × 1019 Nm (Mw 6.9). By comparison with the single inversion of strong motion records, the cumulative slip distribution of joint inversion shows sparser slip distribution with two slip asperities. One common slip asperity extends from the hypocenter southeastward to the ground surface of breakage; another slip asperity, which is unique for joint inversion contributed by 1-Hz GPS waveforms, appears in the deep part of fault where very few aftershocks are occurring. The differential moment rate function of joint and single inversions obviously indicates that rich high frequency waves are radiated in the first three seconds but few low frequency waves.

  7. Constitutive relations between dynamic physical parameters near a tip of the propagating slip zone during stick-slip shear failure

    NASA Astrophysics Data System (ADS)

    Ohnaka, Mitiyasu; Kuwahara, Yasuto; Yamamoto, Kiyohiko

    1987-12-01

    Constitutive relations between physical parameters in the cohesive zone during stick-slip shear failure are experimentally investigated. Stick-slip was generated along a 40 cm long precut fault in Tsukuba granite samples using a servocontrolled biaxial loading apparatus. Dynamic behavior during local breakdown processes near a tip of the slipping zone is revealed; the slip velocity and acceleration are given as a function of the slip displacement and the cohesive (or breakdown) shear stress as a function of the slip velocity. A cycle of the breakdown and restrengthening process of stick-slip is composed of five phases characterized in terms of the cohesive strength and the slip velocity. The cohesive strength can degrade regardless of the slip velocity during slip instabilities. The maximum slip acceleration ümax and the maximum slip velocity u˙max are obtained experimentally as: ümax= {2}/{u cu˙max2}andu˙max= {Δτ b}/{G}v where u c is the critical displacement, Δτb the breakdown stress drop, G the rigidity and v the rupture velocity. These relations are consistent with Ida's theoretical estimation based on the cohesive zone model. The above formula gives good estimates for the maximum slip acceleration of actual earthquakes. The cutoff frequency ƒ maxof the power spectral density of the slip acceleration increases with increasing normal stress; in particular, ƒ maxis found to be directly proportional to the normal stress σn within the normal stress range less than 17 MPa as: ƒ max(kHz) = 4.0σ n(MPa) σn<17(MPa) ƒ maxincrease with an increase in u˙max or ümax. All these results lead to the conclusion that ümax, u˙max and ƒ max increase with increasing normal stress. This is consistent with a previous observation that τb increases with increasing normal stress. The above empirical linear relation between ƒ max and σn can be explained by a linear dependence of Δτb on σn. The size-scale dependence of physical parameters is discussed, and such

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    If seismic-aseismic transitions in fault rocks are to be recognized from microstructures preserved in natural fault rocks, an understanding of the microphysical mechanisms that produce such microstructures is needed. We report on microstructures recovered from dry direct shear experiments on (simulated) dry calcite gouge, performed at 50 MPa normal stress, 18-150°C and low sliding velocities (0.1-10 μm/s). The mechanical data show a transition from velocity strengthening below ~80°C to velocity weakening slip at higher temperatures. We investigated both loose gouge fragments and thin sections, characterizing the microstructures at the mm- to nm-scales. All deformed samples split along a shear band fabric defined by mainly R1- and boundary shears. Viewed normal to the shear plane, these bands commonly showed shiny, elongate patches aligned, and striated, parallel to the shear direction. These patches were especially common in samples tested below 80°C, though shear band splitting was less well-developed above 80°C so that even if the shiny patches formed at higher temperature they were less frequently exposed. Scanning Electron Microscopy (SEM) applied to shiny patches formed in samples sheared at room temperature showed the presence of elongate, streaked out sub-micron-sized particles oriented parallel to the shear direction. Transmitted light optical microscopy of thin sections cut normal to the shear plane and parallel to the shear direction, combined with Focused Ion Beam (FIB) - SEM on loose gouge fragments, showed that the shiny surfaces correspond with shear bands characterized by extreme grain size reduction and sintered sub-micron-particles. Transmission Electron Microscopy (TEM) further revealed that the cores of the shear bands consist of nanocrystallites some 20 nm in size, with a Crystallographic Preferred Orientation (CPO). Our results demonstrate that mirror-like nanocrystalline slip zones can form in calcite gouge sheared at shallow crustal

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

    USGS Publications Warehouse

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

    1991-01-01

    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.

  10. Strain Wave during the Transient Process of Fault Unstable Slip

    NASA Astrophysics Data System (ADS)

    Guo, L.; Liu, L.

    2011-12-01

    The "stick-slip" model was proposed as an important mechanism for shallow-focus earthquakes. The study on the transient process of fault unstable slip failure is helpful for understanding the earthquake preparatory process, the mechanism of energy released, the precursor and after shake effect. Double shear frictional experiments are conducted for simulating "stick-slip" phenomenon, and a specially designed multi-channel super dynamic strain field observation system is employed to acquire dada continuously with the sample rate of 3,400 samples/second. The rock deformation process can be recorded in detail, especially in the moment of unstable slip (The unstable slip duration is less than two second in experiments). The strain results from super dynamic strain field observation system show that multi-frequency components and tremendous amplitude fluctuation are included in strain signals along the fault. There are three clear phases during the unstable slip progress: pre-slip (phase I), high-frequency strain vibration (phase II) and strain regulating to stop (phase III). Each phase has its own characteristics on duration, strain rate, frequency, amplitude and energy release. There are strong fluctuations in duration of approximately 70ms in phase II. The frequency and maximum amplitude are 300-400Hz and 150~300μɛ respectively. Main strain energy release takes place at phase II, less than one-tenth of the total slip time, so that the whole course of dislocation or stress drop would not be taken as earthquake simply at least in laboratory. The phase characteristic of the strain wave is probably its inherent attribute of unstable slip process and independent of dynamical loading conditions. The elastic rebound phenomena, considered as one classic earthquake generation model, can be observed clearly by analyzing the rotation of the principal strain axis with strain variation. The rotated angle ranges from 5° to 15° typically. The value and location of precursor slip

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

    NASA Astrophysics Data System (ADS)

    Thatcher, Wayne; Murray-Moraleda, Jessica

    2010-05-01

    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

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

    USGS Publications Warehouse

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

    2001-01-01

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

  13. Stick-Slip Friction of PDMS Surfaces for Bioinspired Adhesives.

    PubMed

    Xue, Longjian; Pham, Jonathan T; Iturri, Jagoba; Del Campo, Aránzazu

    2016-03-15

    Friction plays an important role in the adhesion of many climbing organisms, such as the gecko. During the shearing between two surfaces, periodic stick-slip behavior is often observed and may be critical to the adhesion of gecko setae and gecko-inspired adhesives. Here, we investigate the influence of short oligomers and pendent chains on the stick-slip friction of polydimethylsiloxane (PDMS), a commonly used material for bioinspired adhesives. Three different stick-slip patterns were observed on these surfaces (flat or microstructured) depending on the presence or absence of oligomers and their ability to diffuse out of the material. After washing samples to remove any untethered oligomeric chains, or after oxygen plasma treatment to convert the surface to a thin layer of silica, we decouple the contributions of stiffness, oligomers, and pendant chains to the stick-slip behavior. The stick phase is mainly controlled by the stiffness while the amount of untethered oligomers and pendant chains available at the contact interface defines the slip phase. A large amount of oligomers and pendant chains resulted in a large slip time, dominating the period of stick-slip motion. PMID:26903477

  14. Laboratory observations of fault-normal vibrations during stick slip

    SciTech Connect

    Bodin, P.; Brown, S.; Matheson, D.

    1998-12-01

    We report laboratory observations of interface separation waves during stick slip on a fault in a uniform polymer material. Our observations, made at stress levels expected at midcrustal depths, share many macroscopic properties with ruptures of faults in rocks. We observed a drop in fault-normal stress shortly before the onset of, and during, stick slip at points along the fault during a rupture. We suggest that {ital P} wave energy in front of the propagating rupture tip is responsible for the drop in normal stress. We also interpret that stick slip took place within a traveling slip pulse, and we suggest that the dynamic stress drop within the slipping patch exceeded the overall static stress drop by a factor of at least 5 within a few millimeters of the fault. Our experiments did not resolve whether the fault surfaces actually separate or if fault-normal stress is just greatly reduced. In either case the net result is that fault slip is permitted to take place with much less frictional resistance than that expected from the applied load. Our observations provide laboratory evidence that fault-normal vibrations may play an important role in sustaining a rupture by facilitating the propagation of a transient instability. Faults may appear weak in part because they are dynamically weakened as they slip during rupture while retaining their strength during the interseismic period. {copyright} 1998 American Geophysical Union

  15. Can slip heterogeneity be linked to earthquake recurrence?

    NASA Astrophysics Data System (ADS)

    Chen, Kate Huihsuan; Chen, Iyin; Kim, Ahyi

    2016-07-01

    The rupture process of two M4 repeating earthquake sequences in eastern Taiwan with contrasting recurrence behavior is investigated to demonstrate a link between slip heterogeneity and earthquake recurrence. The M3.6-3.8 quasiperiodic repeating earthquakes characterized by 3 years recurrence interval reveal overlapped slip concentrations. Inferred slip distribution for each event illustrates two asperities with peak slip of 47.7 cm and peak stress drop of 151.1 MPa. Under the influence of nearby M6.9 event, the M4.3-4.8 repeating earthquakes separated only by 6-87 min, however, reveal an aperiodic manner. There is a distinct rupture characteristic without overlap in the slip areas, suggesting that shortening of the recurrence interval by the nearby large earthquake may change the slip heterogeneity in a repeatedly ruptured asperity. We conclude that the inherent heterogeneity of stress and strength could influence the distribution of coseismic slip, which is strongly tied to the recurrence behavior.

  16. Slip-accelerated falling drop along a vertical fiber

    NASA Astrophysics Data System (ADS)

    Wei, Hsien-Hung; Halpern, David

    2014-11-01

    Effects of wall slip on the motion of a falling drop along a vertical fiber are investigated theoretically. Using lubrication theory, we derive an interfacial evolution equation to describe how the drop's travelling speed and height vary with the Bond number and the slip length. Our numerical results reveal that the drop can travel much faster than the one without slip due to the dramatic increase in the travelling speed with the slip length. The drop height is also found to rapidly increase with the slip length, which is due to enchanced capillary draining from the film into the drop. For Bond number above some critical value, however, capillary draining is suppressed and hence so is the drop height. We determine how the critical Bond number varies with the slip length. For a sufficiently large Bond number, the relevant Kuramoto-Sivashinsky equation is also derived to reveal how the suppression of the capillary instability is mediated by slip effects in the weakly nonlinear regime.

  17. Effective slip in pressure-driven Stokes flow

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Stone, Howard A.

    2003-08-01

    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.

  18. Dynamic Ridges and Valleys in a Strike-Slip Environment

    NASA Astrophysics Data System (ADS)

    Duvall, Alison R.; Tucker, Gregory E.

    2015-10-01

    Strike-slip faults have long been known for characteristic near-fault landforms such as offset rivers and strike-parallel valleys. In this study, we use a landscape evolution model to investigate the longer-term, catchment-wide landscape response to horizontal fault motion. Our results show that strike-slip faulting induces a persistent state of disequilibrium in the modeled landscapes brought about by river lengthening along the fault alternating with abrupt shortening due to stream capture. The models also predict that, in some cases, ridges oriented perpendicular to the fault migrate laterally in conjunction with fault motion. We find that ridge migration happens when slip rate is slow enough and/or soil creep and river incision are efficient enough that the landscape can respond to the disequilibrium brought about by strike-slip motion. Regional rock uplift relative to baselevel also plays a role, as topographic relief is required for ridge migration. In models with faster horizontal slip rates, stronger rocks, or less efficient hillslope transport, ridge mobility is limited or arrested despite the continuance of river lengthening and capture. In these cases, prominent steep, fault-facing facets form along well-developed fault valleys. Comparison of landscapes adjacent to fast-slipping (>30 mm/yr) and slower-slipping (≤1 mm/yr or less) strike-slip faults in California, USA, reveals features that are consistent with model predictions. Our results highlight a potential suite of geomorphic signatures that can be used as indicators of horizontal crustal motion and geomorphic processes in strike-slip settings even after river capture has diminished or erased apparent offset along the fault.

  19. Slip-stick and the evolution of frictional strength.

    PubMed

    Ben-David, Oded; Rubinstein, Shmuel M; Fineberg, Jay

    2010-01-01

    The evolution of frictional strength has great fundamental and practical importance. Applications range from earthquake dynamics to hard-drive read/write cycles. Frictional strength is governed by the resistance to shear of the large ensemble of discrete contacts that forms the interface that separates two sliding bodies. An interface's overall strength is determined by both the real contact area and the contacts' shear strength. Whereas the average motion of large, slowly sliding bodies is well-described by empirical friction laws, interface strength is a dynamic entity that is inherently related to both fast processes such as detachment/re-attachment and the slow process of contact area rejuvenation. Here we show how frictional strength evolves from extremely short to long timescales, by continuous measurements of the concurrent local evolution of the real contact area and the corresponding interface motion (slip) from the first microseconds when contact detachment occurs to large (100-second) timescales. We identify four distinct and inter-related phases of evolution. First, all of the local contact area reduction occurs within a few microseconds, on the passage of a crack-like front. This is followed by the onset of rapid slip over a characteristic time, the value of which suggests a fracture-induced reduction of contact strength before any slip occurs. This rapid slip phase culminates with a sharp transition to slip at velocities an order of magnitude slower. At slip arrest, 'ageing' immediately commences as contact area increases on a characteristic timescale determined by the system's local memory of its effective contact time before slip arrest. We show how the singular logarithmic behaviour generally associated with ageing is cut off at short times. These results provide a comprehensive picture of how frictional strength evolves from the short times and rapid slip velocities at the onset of motion to ageing at the long times following slip arrest. PMID

  20. Joint fluid Gram stain

    MedlinePlus

    Gram stain of joint fluid ... A sample of joint fluid is needed. The fluid sample is sent to a lab where a small drop is placed in a ... on how to prepare for the removal of joint fluid, see joint fluid aspiration .

  1. Local Flow Field and Slip Length of Superhydrophobic Surfaces.

    PubMed

    Schäffel, David; Koynov, Kaloian; Vollmer, Doris; Butt, Hans-Jürgen; Schönecker, Clarissa

    2016-04-01

    While the global slippage of water past superhydrophobic surfaces has attracted wide interest, the local distribution of slip still remains unclear. Using fluorescence correlation spectroscopy, we performed detailed measurements of the local flow field and slip length for water in the Cassie state on a microstructured superhydrophobic surface. We revealed that the local slip length is finite, nonconstant, anisotropic, and sensitive to the presence of surfactants. In combination with numerical calculations of the flow, we can explain all these properties by the local hydrodynamics. PMID:27081981

  2. Local void and slip model used in BODYFIT-2PE

    SciTech Connect

    Chen, B.C.J.; Chien, T.H.; Kim, J.H.; Lellouche, G.S.

    1983-01-01

    A local void and slip model has been proposed for a two-phase flow without the need of fitting any empirical parameters. This model is based on the assumption that all bubbles have reached their terminal rise velocities in the two-phase region. This simple model seems to provide reasonable calculational results when compared with the experimental data and other void and slip models. It provides a means to account for the void and slip of a two-phase flow on a local basis. This is particularly suitable for a fine mesh thermal-hydraulic computer program such as BODYFIT-2PE.

  3. Simulations of slip flow on nanobubble-laden surfaces

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  4. Micro PIV measurement of slip flow on a hydrogel surface

    NASA Astrophysics Data System (ADS)

    Kikuchi, K.; Mochizuki, O.

    2014-06-01

    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.

  5. Local Flow Field and Slip Length of Superhydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Schäffel, David; Koynov, Kaloian; Vollmer, Doris; Butt, Hans-Jürgen; Schönecker, Clarissa

    2016-04-01

    While the global slippage of water past superhydrophobic surfaces has attracted wide interest, the local distribution of slip still remains unclear. Using fluorescence correlation spectroscopy, we performed detailed measurements of the local flow field and slip length for water in the Cassie state on a microstructured superhydrophobic surface. We revealed that the local slip length is finite, nonconstant, anisotropic, and sensitive to the presence of surfactants. In combination with numerical calculations of the flow, we can explain all these properties by the local hydrodynamics.

  6. Exhumation and continental strike-slip fault systems: Introduction

    USGS Publications Warehouse

    Roeske, S.M.; Till, A.B.; Foster, D.A.; Sample, J.C.

    2007-01-01

    Metamorphic rocks adjacent to and within strike-slip faultsystems occur in a wide range of tectonic settings. Detailed studies show that for a number of these locales a significant part of the exhumation occurred during strike-slip fault motion, but the specific processes involved are often cryptic. Although some sites share characteristic features, such as metamorphic rocks exhumed in extensional step-overs within overall transtensional systems, no one common theme emerges from all of the studies. Our understanding of the variables that control continental strike-slip faults' interaction with mid- to lower-crustal structures is still primitive.

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

    USGS Publications Warehouse

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

    2015-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  9. Seasonal variation of slipped capital femoral epiphysis.

    PubMed

    Maffulli, Nicola; Douglas, A Stuart

    2002-01-01

    During the 18-year period 1980-1997, 1103 patients were treated as in-patients for slipped capital femoral epiphysis (SCFE) in Scottish hospitals. This paper reports a significant seasonal variation, especially in male patients, with an excess admitted in the autumn. Examining the physiological seasonality of the monthly increment of growth in height and weight in childhood, we hypothesised that these physiological rhythms, while not pathogenetic, may be responsible for the timing of the seasonal features of SCFE. Previously published studies suggest that the average time between first symptoms and diagnosis is 3 to 5 months. The condition may start with the spring peak in growth and become more symptomatic with the autumn peak in weight. In conclusion, we report a new epidemiological finding, but, in accordance with other studies, we cannot provide a certain aetiological explanation. The timing, but not the pathogenesis, of admission to hospital for a SCFE might be related to the timing in the year of seasonal increments of height in spring and weight in autumn. It is tempting to draw attention to associations with environmental features. For example, in autumn there is the most rapid annual fall in temperature, and the hours of darkness are increasing from the autumn equinox to the winter solstice. However, there is no reason to conclude that these associations have anything to do with aetiology. PMID:11866078

  10. From frictional fingers to stick slip bubbles

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  11. Effect of Nonlinear Joints on Space Deployable Truss Structures

    NASA Astrophysics Data System (ADS)

    Guo, Hongwei; Deng, Zhongquan; Wu, Xiang; Liu, Rongqiang

    2012-07-01

    Joints nonlinearities with characteristics of freeplay and hysteresis are analyzed by describing joint nonlinear force-displacement based on describing function method. The nonlinear dynamic responses of the one- DOF system with joints under different exciting force levels are presented in the charts. The influence of the characterizing parameters, e.g., gaps, slipping forces of the joints on nonlinearities is analyzed. The nonlinear effects of freeplay and hysteresis present that the dynamic responses switch from one resonance frequency to another frequency when amplitude exceed the demarcation values. The hysteresis nonlinearity contributes nonlinear damping to the system. Dynamic responses of the modular beam-like deployable joint- dominated truss structure are tested under different sinusoidal exciting force levels which show obvious nonlinear behaviors. The nonlinear dynamic behaviors of the truss structure contributed by the joints shows a shift to lower resonance frequency and higher amplitude with the exciting force increases. The nonlinearity of the joints in the tested structure is identified to meet with the hysteresis nonlinearity. The experiment validates that describing method is an effective tool to model the joint nonlinearities.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

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

    SciTech Connect

    Castanho, S.M.; Moreno, R.; Salomoni, A.; Stamenkovic, I.

    1995-09-01

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

  14. TV Ratings for Parents Let Violence, Drinking Slip Through

    MedlinePlus

    ... fullstory_160553.html TV Ratings for Parents Let Violence, Drinking Slip Through Industry guidelines often misleading, study ... don't always reflect the true amount of violence, smoking and drinking in TV shows, a new ...

  15. Slip ring experience in long duration space applications

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Dome-building eruptions have catastrophic potential, with dome collapse leading to devastating pyroclastic flows with almost no precursory warning. During dome growth, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite and gouge. Under extreme friction, pseudotachylyte may form at the conduit margin. Understanding the conduit margin processes is vital to understanding the continuation of an eruption and we postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic "drumbeats", which are so commonly observed at dome-building volcanoes. This view is supported by field evidence in the form of pseudotachylytes identified in lava dome products at Soufrière Hills (Montserrat) and Mount St. Helens (USA). Both eruptions were characterised by repetitive, periodic seismicity and lava spine extrusion of highly viscous magma. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (<10 MPa). Starting from room temperature, frictional melting of the magmas occurs in under 1 s (<< 1 m) at 1.5 m/s (a speed that is achievable during stick-slip motion). At lower velocities melting occurs comparatively later due to dissipation of heat from the slip zone (e.g. 8-15 m at 0.1 m/s). Hence, given the ease with which melting is achieved in volcanic rocks, and considering the high ambient temperatures in volcanic conduits, frictional melting may thus be an inevitable consequence of viscous magma ascent. The shear resistance of the slip zone during the experiment is also monitored. Frictional melting induces a higher resistance to sliding than rock on rock, and viscous processes control the slip zone properties. Variable-rate HVR experiments which mimic

  17. [Study on the compatibility of slip casting aluminous ceramic crowns

    PubMed

    Wan, Q B; Xue, M; You, L; Du, C S; Chao, Y L

    1997-03-01

    One of the key factors for a good slip casting aluminous ceramic crown is good compatibility between its core material and the veneering porcelain.The chemical and thermal compatibility of two slip casting aluminous ceramic crown systems(In-Ceram and GI-I) were investigated by means of SEM and EDAX,thermal shock tests were also performed to evaluate the crazing resistance.The results showed: the crazing resistance of In-Ceram was 158 degrees centigrade,and that of GI-I was degrees centigrade;there existed tightly bonded interfaces between the slip casting aluminous ceramic cores and the veneering porcelains in both of the two systems,where ion transferences were found.The results also suggested good compatibility of the two slip casting aluminous ceramic crown systems. PMID:15159959

  18. Experimental Characterization of a Flexible Thermal Slip Sensor

    PubMed Central

    Francomano, Maria Teresa; Accoto, Dino; Guglielmelli, Eugenio

    2012-01-01

    Tactile sensors are needed for effectively controlling the interaction between a robotic hand and the environment, e.g., during manipulation of objects, or for the tactile exploration of unstructured environments, especially when other sensing modalities, such as vision or audition, become ineffective. In the case of hand prostheses, mainly intended for dexterous manipulation of daily living objects, the possibility of quickly detecting slip occurrence, thus avoiding inadvertent falling of the objects, is prodromal to any manipulation task. In this paper we report on a slip sensor with no-moving parts, based on thermo-electrical phenomena, fabricated on a flexible substrate and suitable for integration on curved surfaces, such as robotic finger pads. Experiments performed using a custom made test bench, which is capable of generating controlled slip velocities, show that the sensor detects slip events in less than 50 ms. This response time is short enough for enabling future applications in the field of hand prosthetics. PMID:23202209

  19. Characterization of Natural Slip Surfaces Relevant to Earthquake Mechanics

    NASA Astrophysics Data System (ADS)

    Chester, J. S.; Kronenberg, A. K.; Chester, F. M.; Guillemette, R. N.

    2003-12-01

    The Punchbowl fault, an ancient trace of the San Andreas, displays extreme localization of displacement to a meters-thick fault core containing an ultracataclasite layer with mesoscale slip surfaces. New maps of the Punchbowl fault slip surface and ultracataclasite produced using optical and electron microscopy document that extreme localization of slip also occurred at the microscopic scale. The prominent mesoscopic scale slip surface is a thin (mm thick), texturally distinct layer of ultracataclasite with a crystal-lattice preferred orientation, as evidenced by uniform birefringence, within which distinct microscopic slip surfaces are evident. Thin sinuous seams and possible injection-like structures of opaque, ultrafine material and thin zones of cataclastic flow occur at the microscopic slip surface. Evidence for multiple episodes of synfaulting mineral alteration and cementation in the surrounding ultracataclasite documents chemical processes likely were important to strength recovery. Overall, microstructural features are consistent with the inference that repeated slip occurred on the mesoscopic-scale slip surface, and that older slip-surfaces are present throughout the ultracataclasite layer. Diffraction-contrast TEM imaging, micro-electron diffraction, quantitative elemental mapping and energy dispersive spectroscopy (EDS) are being used to determine relative abundance and types of crystalline phases, glass, or other friction-induced amorphous phases (e.g., silica gel). Preliminary TEM observations indicate that the ultracataclasite consists almost entirely of ultrafine particles (4 to 400 nm diameter), with rounded relict grains of the host rocks, faulted and unfaulted veins, sheared and kinked clay minerals, and new, euhedral grains. Low permeabilities are implied by the fine grain size and corresponding nm-scale pores. Although rapid slip on mesoscopic scale slip surfaces would be expected to have produced thermal transients, we have not, as yet, found

  20. Slip Updip of Tremor during the 2012 Cascadia ETS Event

    NASA Astrophysics Data System (ADS)

    Hall, K.; Houston, H.

    2014-12-01

    The interplay between tremor and slow slip during ETS has implications for the slip budget of the Cascadia subduction zone. In particular, it can constrain the downdip edge of the locked zone, which informs the hazard assessments for major cities including Seattle, Tacoma, and Vancouver. As shown by Houston (AGU abstract, 2012), slip inferred from GPS extended updip of the seismically-detected tremor in the 2010 M6.8 ETS event. Following the methods used on the 2010 ETS event, we used the PANGA GPS to measure the displacement vectors for 71 stations to analyze a large ETS event in 2012 that extended from Vancouver Island to Southern Washington. We implemented Principal Component Analysis to automatically select the direction and magnitude of the maximum displacement vector. We then inverted these GPS displacements for slip, using the Okada formulation of buried rectangular faults in a halfspace with a grid of 8 by 8 km subfaults based on the McCrory slab model. We performed inversions with either 0th or 2nd order Tikhonov regularization and found that over the 6 weeks of propagation, the 2012 ETS event released moment corresponding to M6.7, in three high-slip regions. We compared two different inversions, one where slip was allowed on a broad regional grid and a tremor-restricted inversion (TRI) where slip was restricted to grid locations where tremor had been detected in the 2012 ETS. We found that the TRI forced the slip to the updip edge of the grid where it reached above 10 cm, which is physically implausible given that this exceeds the slip that can accumulate in an inter-ETS time period. Additionally, the regional grid inversion indicates that 1 to 2 cm of slip occurred 10's of km updip of the western edge of tremor. This further supports the inference from the 2010 event that in northern Washington, the slow slip during an ETS event extends many kilometers updip of the western edge of tremor.

  1. Modelling Paleoearthquake Slip Distributions using a Gentic Algorithm

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  2. Refining the Magnitude of the Shallow Slip Deficit

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S.

    1996-06-01

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

  4. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S.

    1997-03-01

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

  5. Wheel rolling constraints and slip in mobile robots

    SciTech Connect

    Shekhar, S.

    1997-03-01

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

  6. Slipping Rib Syndrome as Persistent Abdominal and Chest Pain.

    PubMed

    Bolaños-Vergaray, Juan Javier; de la Gala García, Francisco; Obaya Rebollar, Juan Carlos; Bové Alvarez, Maria

    2015-11-01

    Slipping rib syndrome is an overlooked cause of persistent abdominal or chest pain. The etiology of this syndrome is not well understood, but the characteristic pain is from hypermobility of the false ribs. Although it is a diagnosis of exclusion, misdiagnosis may lead to an excessive workup. A simple clinical examination via the hooking maneuver is the most significant feature of its diagnosis. We describe the case of a 41-year-old woman with slipping rib syndrome. PMID:26528703

  7. Predicting apparent slip at liquid-liquid interfaces without an interface slip condition

    NASA Astrophysics Data System (ADS)

    Poesio, Pietro; Damone, Angelo; Matar, Omar

    2015-11-01

    We show that if we include a density-dependent viscosity into the Navier-Stokes equations then we can describe, naturally, the velocity profile in the interfacial region, as we transition from one fluid to another. This requires knowledge of the density distribution (for instance, via Molecular Dynamics [MD] simulations, a diffuse-interface approach, or Density Functional Theory) everywhere in the fluids, even at liquid-liquid interfaces where regions of rapid density variations are possible due to molecular interactions. We therefore do not need an artificial interface condition that describes the apparent velocity slip. If the results are compared with the computations obtained from MD simulations, we find an almost perfect agreement. The main contribution of this work is to provide a simple way to account for the apparent slip at liquid-liquid interfaces without relying upon an additional boundary condition, which needs to be calculated separately using MD simulations. Examples are provided involving two immiscible fluids of varying average density ratios, undergoing simple Couette and Poisseuille flows. MIUR through PRIN2012-NANOBridge; Royal Society International Exchange Scheme (IE141486).

  8. Butt Joint Tool Commissioning

    SciTech Connect

    Martovetsky, N N

    2007-12-06

    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.

  9. Steadily propagating slip pulses driven by thermal decomposition

    NASA Astrophysics Data System (ADS)

    Platt, John D.; Viesca, Robert C.; Garagash, Dmitry I.

    2015-09-01

    Geophysical observations suggest that mature faults weaken significantly at seismic slip rates. Thermal pressurization and thermal decomposition are two mechanisms commonly used to explain this dynamic weakening. Both rely on pore fluid pressurization with thermal pressurization achieving this through thermal expansion of native solids and pore fluid and thermal decomposition by releasing additional pore fluid during a reaction. Several recent papers have looked at the role thermal pressurization plays during a dynamically propagating earthquake, but no previous models have studied the role of thermal decomposition. In this paper we present the first solutions accounting for thermal decomposition during dynamic rupture, solving for steady state self-healing slip pulses propagating at a constant rupture velocity. First, we show that thermal decomposition leads to longer slip durations, larger total slips, and a distinctive along-fault slip rate profile. Next, we show that accounting for more than one weakening mechanism allows multiple steady slip pulses to exist at a given background stress, with some solutions corresponding to different balances between thermal pressurization and thermal decomposition, and others corresponding to activating a single reaction multiple times. Finally, we study how the rupture properties depend on the fault properties and show that the impact of thermal decomposition is largely controlled by the ratio of the hydraulic and thermal diffusivities χ = αhy/αth and the ratio of pore pressure generated to temperature rise buffered by the reaction Pr/Er.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  11. Numerical Investigations of the Dynamic Shear Behavior of Rough Rock Joints

    NASA Astrophysics Data System (ADS)

    Huang, Junyu; Xu, Songlin; Hu, Shisheng

    2014-09-01

    The dynamic shear behavior of rock joints is significant to both rock engineering and earthquake dynamics. With the discrete element method (DEM), the dynamic direct-shear tests on the rough rock joints with 3D (sinusoidal or random) surface morphologies are simulated and discussed. Evolution of the friction coefficient with the slip displacement shows that the 3D DEM joint model can accurately reproduce the initial strengthening, slip-weakening, and steady-sliding responses of real rock joints. Energy analyses show that the strengthening and weakening behavior of the rock joint are mainly attributed to the rapid accumulation and release of the elastic energy in the joint. Then, effects of the surface roughness and the normal stress on the friction coefficient and the micro shear deformation mechanisms, mainly volume change and asperity damage, of the rock joint are investigated. The results show that the peak friction coefficient increases logarithmically with the increasing surface roughness, but decreases exponentially with the increasing normal stress. In addition, the rougher rock joint exhibits both higher joint dilation and asperity degradation. However, high normal stress constrains the joint dilation, but promotes the degree of asperity degradation significantly. Lastly, the effects of the 3D surface morphology on the shear behavior of the rock joint are investigated with a directional roughness parameter. It is observed that the anisotropy of the surface roughness consequently results in the variation of the peak friction coefficient of the joint corresponding to different shearing directions as well as the micro shear deformation mechanisms, e.g., the extent of joint dilation.

  12. Slip zone structure and processes in seismogenic carbonate faults

    NASA Astrophysics Data System (ADS)

    Bullock, R. J.; De Paola, N.

    2011-12-01

    High velocity rotary shear experiments performed at seismic slip velocities (>1 m/s) have shown that experimental faults are weak; with increasing displacement, friction coefficient values decrease from Byerlee's values (μ = 0.6-0.85) to values of ~0.1. In carbonate rocks, experimental studies have shown that fault lubrication is due to the operation of multiple dynamic weakening mechanisms (e.g., flash heating, thermal pressurization, nanoparticle lubrication), which are thermally activated due to the frictional heat generated along localized slip surfaces during rapid slip. This study has set out to investigate whether evidence for the operation of these weakening mechanisms can be found in naturally occurring carbonate fault zones. Field studies were carried out on the active Gubbio fault zone (1984, Mw = 5.6) in the northern Apennines of Italy. Jurassic-Oligocene carbonates in the footwall are heavily deformed within a fault core of ~15 m thickness, which contains a number of very well exposed, highly localized principal slip surfaces (PSSs). Fault rocks are predominantly breccias and foliated cataclasites. Microstructural analyses of the PSSs reveal that slip is localized within very narrow principal slip zones (PSZs), ranging from 10-85 μm in thickness, with sub-millimetre scale asperities. PSZs are composed of very fine-grained, orange-brown ultracataclasite gouge containing a high proportion of nano-sized particles. The ultracataclasite commonly displays a foliated texture and sub-micron scale zones of extreme shear localization. A broader slip zone, up to 1.5 mm wide and containing multiple slip surfaces, is associated with the most evolved PSSs; it is located on the opposite side of the PSS to the PSZ. Here, the host rock material is heavily fractured, abraded and altered, sometimes with an ultracataclasite matrix. The surrounding wall rock often appears to have a porous texture, and calcite crystals within the slip zone have altered rims with lobate

  13. Nucleation of Dynamic Slip on a Hydraulically Fractured Fault

    NASA Astrophysics Data System (ADS)

    Azad, M. H.; Garagash, D.; Satish, M.

    2014-12-01

    This work is concerned with the relationship between hydraulic fracturing injection and induced seismicity on a fault. This is applicable to safety hazard assessment of the nucleation of dynamic slip along the fault as a result of hydraulic fracturing injection into or near the fault. The hydraulic fracture (HF) injection into the fault can be purposeful, for instance to trigger an earthquake in more controllable conditions than would happen otherwise; or in order to use the open portion of the fault as a reservoir heat exchanger for the extraction of geothermal heat. It can be unintentional due to lack of accurate subsurface characterization prior to the injection. Injection with constant flow rate into an impermeable fault will initiate slip along the fault. The slip occurs due to the lack of frictional strength along the open part of the fault (the hydraulic fracture) as well as from the reduction of the normal stress ahead of the hydraulic fracture front. Slip in front of the hydraulic fracture is assumed to degrade the tensile strength of the fault to zero, so that the hydraulic fracture propagation takes place in the viscous-dominated regime (i.e. dominated by viscous losses in the fluid flow inside the fracture). In our model, the nucleation of dynamic slip is related to the slip-weakening nature of the friction, and depends on in-situ stresses, pressure distribution inside the hydraulic fracture, and the evolving length of the hydraulic fracture. The results of this study show that the growth of the fault slipping patch remains stable, with no episode of dynamic rupture, when the background shear stress τb is smaller than the residual shear strength τr of the fault under ambient conditions. Otherwise (τb > τr), nucleation takes place when the extent of the hydraulic fracture reaches the critical length ~ (μ/τp) δc, where μ is the elastic shear modulus of the rock, τp is the peak shear strength of the fault, and δc is the characteristic slip

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2015-04-01

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

  16. Slip distribution, strain accumulation and aseismic slip on the Chaman Fault system

    NASA Astrophysics Data System (ADS)

    Amelug, F.

    2015-12-01

    The Chaman fault system is a transcurrent fault system developed due to the oblique convergence of the India and Eurasia plates in the western boundary of the India plate. To evaluate the contemporary rates of strain accumulation along and across the Chaman Fault system, we use 2003-2011 Envisat SAR imagery and InSAR time-series methods to obtain a ground velocity field in radar line-of-sight (LOS) direction. We correct the InSAR data for different sources of systematic biases including the phase unwrapping errors, local oscillator drift, topographic residuals and stratified tropospheric delay and evaluate the uncertainty due to the residual delay using time-series of MODIS observations of precipitable water vapor. The InSAR velocity field and modeling demonstrates the distribution of deformation across the Chaman fault system. In the central Chaman fault system, the InSAR velocity shows clear strain localization on the Chaman and Ghazaband faults and modeling suggests a total slip rate of ~24 mm/yr distributed on the two faults with rates of 8 and 16 mm/yr, respectively corresponding to the 80% of the total ~3 cm/yr plate motion between India and Eurasia at these latitudes and consistent with the kinematic models which have predicted a slip rate of ~17-24 mm/yr for the Chaman Fault. In the northern Chaman fault system (north of 30.5N), ~6 mm/yr of the relative plate motion is accommodated across Chaman fault. North of 30.5 N where the topographic expression of the Ghazaband fault vanishes, its slip does not transfer to the Chaman fault but rather distributes among different faults in the Kirthar range and Sulaiman lobe. Observed surface creep on the southern Chaman fault between Nushki and north of City of Chaman, indicates that the fault is partially locked, consistent with the recorded M<7 earthquakes in last century on this segment. The Chaman fault between north of the City of Chaman to North of Kabul, does not show an increase in the rate of strain

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  18. Slip Running Reconnection in Magnetic Flux Ropes

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Magnetic flux ropes are due to helical currents and form a dense carpet of arches on the surface of the sun. Occasionally one tears loose as a coronal mass ejection and its rope structure can be detected by satellites close to the earth. Current sheets can tear into filaments and these are nothing other than flux ropes. Ropes are not static, they exert mutual ěc{J}×ěc{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

  19. Regional Slip Tendency Analysis of the Great Basin Region

    DOE Data Explorer

    Faulds, James E.

    2013-09-30

    Slip and dilation tendency on the Great Basin fault surfaces (from the USGS Quaternary Fault Database) were calculated using 3DStress (software produced by Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by the measured ambient stress field. - Values range from a maximum of 1 (a fault plane ideally oriented to slip or dilate under ambient stress conditions) to zero (a fault plane with no potential to slip or dilate). - Slip and dilation tendency values were calculated for each fault in the Great Basin. As dip is unknown for many faults in the USGS Quaternary Fault Database, we made these calculations using the dip for each fault that would yield the maximum slip or dilation tendency. As such, these results should be viewed as maximum slip and dilation tendency. - The resulting along‐fault and fault‐to‐fault variation in slip or dilation potential is a proxy for along fault and fault‐to‐fault variation in fluid flow conduit potential. Stress Magnitudes and directions were calculated across the entire Great Basin. Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson‐Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005). The minimum horizontal stress direction (Shmin) was contoured, and spatial bins with common Shmin directions were calculated. Based on this technique, we subdivided the Great Basin into nine regions (Shmin <070, 070140). Slip and dilation tendency were calculated using 3DStress for the faults within each region using the mean Shmin for the region. Shmin variation throughout Great Basin

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

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  1. Metatarsal phalangeal joint arthroscopy.

    PubMed

    Shonka, T E

    1991-01-01

    An overview of metatarsophalangeal joint (MPJ) arthroscopy is presented. Indications, technique, and perioperative management are discussed. The author believes it is the operative treatment of choice for various pathology encountered in this joint. PMID:2002183

  2. Culture - joint fluid

    MedlinePlus

    Joint fluid culture ... fungi, or viruses grow. This is called a culture. If these germs are detected, other tests may ... is no special preparation needed for the lab culture. How to prepare for the removal of joint ...

  3. Hip joint replacement - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100006.htm Hip joint replacement - series—Normal anatomy To use the sharing ... to slide 5 out of 5 Overview The hip joint is made up of two major parts: the ...

  4. Hip joint injection

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/007633.htm Hip joint injection To use the sharing features on this ... injection is a shot of medicine into the hip joint. The medicine helps relieve pain and inflammation. It ...

  5. Hip joint replacement

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002975.htm Hip joint replacement To use the sharing features on this page, please enable JavaScript. Hip joint replacement is surgery to replace all or part ...

  6. Knee joint replacement - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100088.htm Knee joint replacement - series—Normal anatomy To use the sharing ... of 4 Overview The knee is a complex joint. It contains the distal end of the femur ( ...

  7. Knee joint replacement

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002974.htm Knee joint replacement To use the sharing features on this page, please enable JavaScript. Knee joint replacement is a surgery to replace a knee ...

  8. Large displacement spherical joint

    DOEpatents

    Bieg, Lothar F.; Benavides, Gilbert L.

    2002-01-01

    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.

  9. Temporomandibular Joint Dysfunction

    MedlinePlus

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

  10. Sacroiliac joint pain - aftercare

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000610.htm Sacroiliac joint pain - aftercare To use the sharing features on this page, please enable JavaScript. The sacroiliac joint (SIJ) is a term used to describe the ...

  11. Hot, Fast Faults: Evidence for High-Temperature Slip on Exhumed Faults, and Insights into Seismic Slip Processes

    NASA Astrophysics Data System (ADS)

    Evans, J. P.; Ault, A. K.; Janecke, S. U.; Prante, M. R.

    2015-12-01

    Microstructural and geochemical techniques combined with prior observations of naturally occurring faults provide insights into slip rates and slip dimensions of seismicity. We review four indicators for high coseismic paleotemperatures in brittle to semi-brittle faults from a wide range of tectonic settings with mm to km of slip. Thin, high-gloss, Fe-rich slip surfaces indicate high-temperature slip occurred on mm- to m-scales. Elliptical and circular zones of concentric iridescence indicate localized sites of elevated temperature that may be caused by heating at asperity contacts. The surface iridescence is associated with changes in Fe oxidation states detected by X-Ray photoelectron spectroscopy. Minimum temperature increases of 300 °C above ambient are supported by geochemical arguments and up to 800 °C are supported by analogs to high-speed friction experiments in steels and ceramics firing in reduced conditions. The presence of clay-rich foliated fault-related rocks, and the presence of nm- to mm-thick clay coatings indicate that syn-kinematic endothermic reactions occur at a range of scales. We suggest these features reflect temperature increases of ≥100-200 °C for activation energy required to drive the clay alteration is sourced from seismic energy and Schleicher-van der Pluijm-type slip surfaces to record instantaneous slip. Dense, low porosity planar porcelainite zones mm- to cm-thick along fault surfaces are the result of sintering of quartz-clay-feldspar mixtures and indicate T≥1000 °C localized along the surfaces, the result of post-slip cooling. Highly indurated, ultrafine fault-related rocks often consists of comminuted grains, vein fragments, and neocrystallized grains that represent retrograde cooling or alteration after peak heating. These observations and those of other recent workers indicate that many naturally occurring exhumed faults record elevated temperatures. In many cases, careful observations can delineate fault slip

  12. Stress inversion of heterogeneous fault-slip data with unknown slip sense: An objective function algorithm contouring method

    NASA Astrophysics Data System (ADS)

    Hansen, John-Are; Bergh, Steffen G.; Osmundsen, Per Terje; Redfield, Tim F.

    2015-01-01

    We propose a new method for stress inversion and separation of principal stress states from heterogeneous fault-slip data. The method is semi-automatic, and is based on the moment method of stress inversion (Fry 1999) in combination with the objective function algorithm (OFA) for stress separation (Shan et al 2003). In the presented routine we randomly partition the heterogeneous fault-slip dataset into subsets ranging between one and six. The number of subsets K represents the number of possible mixed stress states in the fault-slip dataset. For each partition number K, we run the OFA 1000 times. Following this we plot and contour the principal stress axes, corresponding to the minimum value of the objective function for each run, in a stereonet. By evaluating how solution clusters of principal stress axes change with increasing number of subsets K, we are able to determine the number of mixed stress states and their optimal solutions for heterogeneous fault-slip datasets. While the numbers of subsets are underestimated, solution-clusters of principal stress axes represent average stress states. However, once the correct number of subsets is reached, solution clusters align with the slip-generating principal stress axes. The solution clusters then become stable, and overestimating the number of subsets does not significantly alter their orientation. The partition number K when stability is obtained thus determines the number of mixed stress states in the heterogeneous dataset, while the corresponding highest density solution clusters give the best estimate of the slip-generating principal stress axes and corresponding stress shape ratios. The inversion routine is tested and confirmed using synthetic data and fault-slip data from the Gullkista fault in Northern Norway. Because the stress calculation is based on the moment method, the inversion routine is insensitive to the correct assessment of slip sense, and only requires the slip vector and orientation of the

  13. Slipping of the foot on the floor when pulling a pallet truck.

    PubMed

    Li, Kai Way; Chang, Chien-Chi; Chang, Wen-Ruey

    2008-11-01

    Workers pulling pallet trucks are likely to slip when pulling and stepping on a low-friction floor. This study investigated the slipping of male participants when pulling a pallet truck, walking backward, and stepping on either a dry, wet, or glycerol-contaminated vinyl surface. The weight of the load on the truck was either low (0 kg), medium (295 kg), or high (568 kg). A motion-tracking system was used to collect the three-dimensional coordinates of the markers on the shoes. It was found that subjects might slip either upon landing of the leading foot on the toe (slip I) or before taking off of the lagging foot on the heel (slip II). The results indicated that the slip distances for both types of slip were significantly affected by the load and surface conditions and their interactions. Micro-slips (slips between 0.1 and 3 cm) and midi-slips (slips between 3 and 10 cm) were more common in slip I than in slip II. On glycerol-contaminated surfaces, the probabilities of a slide, or a slip more than 10 cm, for both slips I and II were over 40%. The implications of the results were discussed. PMID:18222414

  14. Sacroiliac joint imaging.

    PubMed

    Tuite, Michael J

    2008-03-01

    The sacroiliac (SI) joint has several unique anatomical features that make it one of the more challenging joints to image. The joint is difficult to profile well on radiographic views, and therefore the radiographic findings of sacroiliitis are often equivocal. Computed tomography images can usually show the findings of sacroiliitis and osteoarthritis earlier than radiographs. Magnetic resonance imaging performed with proper sequences is excellent for diagnosing even very early sacroiliitis and for following treatment response. The SI joint is often involved in patients with osteoarthritis or one of the inflammatory spondyloarthritides, most notably ankylosing spondylitis. Ankylosing spondylitis often presents with sacroiliitis, which appears as erosions, sclerosis, and joint space narrowing, eventually leading to ankylosis. Several disorders can cause sacroiliitis-like changes of the joint, including hyperparathyroidism and repetitive shear-stress injuries in athletes. The joint can become painful during pregnancy as it widens and develops increased motion, and some postpartum women develop iliac sclerosis adjacent to the joint termed osteitis condensans ilii. Another cause of SI joint pain is a disorder called sacroiliac joint dysfunction, which typically has few abnormal imaging findings. Patients with SI joint dysfunction, as well as sacroiliitis, often get relief from image-guided SI joint therapeutic injections. PMID:18382946

  15. Joint Enrollment Report, 2014

    ERIC Educational Resources Information Center

    Iowa Department of Education, 2014

    2014-01-01

    The Iowa Department of Education collects information on joint enrollment in Iowa's 15 community colleges. Jointly enrolled students are high school students enrolled in community college credit coursework. Most jointly enrolled students enroll through Senior Year Plus (SYP) programs such as Postsecondary Enrollment Options (PSEO) and concurrent…

  16. Seismic velocity change and slip rate during the 2006 Guerrero (Mexico) slow slip event

    NASA Astrophysics Data System (ADS)

    Rivet, Diane; Radiguet, Mathilde; Campillo, Michel; Cotton, Fabrice; Shapiro, Nikolai; Krishna Singh, Shri; Kostoglodov, Vladimir

    2010-05-01

    We measure temporal change of the seismic velocity in the crust below the Guerrero region during the 2006 slow sleep event (SSE). We use repeated cross-correlations of ambient seismic noise recorded at 26 broad-band stations of the MesoAmerica Seismic Experiment (MASE). The cross-correlations are computed over 90 days with a moving window of 10 days from January 2005 to July 2007. To insure measurements independent of noise source variations, we only take into account the travel time change within the coda. For period of 8 to 20s, we observe a decrease in velocity starting in April 2006 with a maximum change of -0.3% of the initial velocity in June 2006. At these periods, the Rayleigh waves are sensitive to velocity changes down to the lower crust. In the other hand, we compute the deformation rate below the MASE array from a slip propagation model of the SSE observed by means of the displacement time-series of 15 continuous GPS stations. Slip initiates in the western part of the Guerrero Gap and propagates southeastward. The propagation velocity is of the order of 1 km/day. We then compare the seismic velocity change measured from continuous seismological data with the deformation rate inferred from geodetic measurements below the MASE array. We obtain a good agreement between the time of maximal seismic velocity change (July 2006) and the time of maximum deformation associated with the SSE (July to August 2006). This result shows that the long-term velocity change associated with the SSE can be detected using continuous seismic recordings. Since the SSE does not emit seismic waves, which interact with the superficial layers, the result indicates that the velocity change is due to deformation at depth.

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

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

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

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

    NASA Astrophysics Data System (ADS)

    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

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Recovering information on past (i.e., last 102-104 yrs) large earthquakes on faults is a challenge. The classical approach -especially used on strike-slip faults- consists in searching morphological markers such as river channels, streams, alluvial fans, ridges or terrace risers, etc, that would be offset by the fault, and measure these offsets by reconstructing the original position and shape of the markers. Combined with the dating of the offset markers, this morphotectonic paleoseismological approach may provide information on the slips and ages of the most recent earthquakes on the fault under study. Yet, the approach is complex as it depends on the recognition of unambiguous paired markers on either side of the fault. And our capability to recognize similar markers on either side of a fault in turn greatly depends on the 'evolution' that these markers may have sustained subsequently to their very first slip disruption. Did the repeating earthquake slip events modify their surface appearance? Did their morphology and position (ex: burying, destruction, modification, etc) evolve with the sedimentation and erosion that might have occurred during the fault history? Etc. These questions have rarely been approached for they are difficult to address in natural settings. And as we are unable to answer them in the natural cases that we study, the slip reconstructions that we provide are generally uncertain as they are likely based on an incomplete or biased record of the past fault slips. Therefore, the objective of our work is to contribute to better understand and document the nature and 'evolution' of the morphological markers that are commonly used in morphotectonic and paleoseismological analyses, especially along strike-slip faults. We approach these questions experimentally. We have developed an original experimental set-up made to simulate repeated slip events on a strike-slip fault placed in a wet environment sustaining sedimentation and erosion. The fault

  20. Multi-asperity models of slow slip and tremor

    NASA Astrophysics Data System (ADS)

    Ampuero, Jean Paul; Luo, Yingdi; Lengline, Olivier; Inbal, Asaf

    2016-04-01

    Field observations of exhumed faults indicate that fault zones can comprise mixtures of materials with different dominant deformation mechanisms, including contrasts in strength, frictional stability and hydrothermal transport properties. Computational modeling helps quantify the potential effects of fault zone heterogeneity on fault slip styles from seismic to aseismic slip, including slow slip and tremor phenomena, foreshocks sequences and swarms, high- and low-frequency radiation during large earthquakes. We will summarize results of ongoing modeling studies of slow slip and tremor in which fault zone structure comprises a collection of frictionally unstable patches capable of seismic slip (tremorgenic asperities) embedded in a frictionally stable matrix hosting aseismic transient slips. Such models are consistent with the current view that tremors result from repeated shear failure of multiple asperities as Low Frequency Earthquakes (LFEs). The collective behavior of asperities embedded in creeping faults generate a rich spectrum of tremor migration patterns, as observed in natural faults, whose seismicity rate, recurrence time and migration speed can be mechanically related to the underlying transient slow slip rate. Tremor activity and slow slip also responds to periodic loadings induced by tides or surface waves, and models relate tremor tidal sensitivity to frictional properties, fluid pressure and creep rate. The overall behavior of a heterogeneous fault is affected by structural parameters, such as the ratio of stable to unstable materials, but also by time-dependent variables, such as pore pressure and loading rate. Some behaviors are well predicted by homogenization theory based on spatially-averaged frictional properties, but others are somewhat unexpected, such as seismic slip behavior found in asperities that are much smaller than their nucleation size. Two end-member regimes are obtained in rate-and-state models with velocity-weakening asperities

  1. Nonoperative treatment of slipped capital femoral epiphysis: a scientific study

    PubMed Central

    2011-01-01

    Background Treatment of the Slipped Capital Femoral Epiphysis remains a cause of concern due to the fact that the true knowledge of the etiopathogeny is unknown, as well as one of its major complications: chondrolysis. The conservative treatment remains controversial; it has been overlooked in the studies and subjected to intense criticism. The purpose of this study is to investigate the results of treatment on the hip of patients displaying slipped capital femoral epiphysis, using the plaster cast immobilization method and its link to chondrolysis. Methods The research was performed based on the study of the following variables: symptomatology, and the degree of slipping. A hip spica cast and bilateral short/long leg casts in abduction, internal rotation with anti-rotational bars were used for immobilizing the patient's hip for twelve weeks. Statistical analysis was accomplished by Wilcoxon's marked position test and by the Fisher accuracy test at a 5% level. Results A satisfactory result was obtained in the acute group, 70.5%; 94%; in the chronic group (chronic + acute on chronic). Regarding the degree of the slipping, a satisfactory result was obtained in 90.5% of hips tested with a mild slip; in 76% with moderate slip and 73% in the severe slip. The statistical result revealed that a significant improvement was found for flexion (p = 0.0001), abduction (p = 0.0001), internal rotation (p = 0.0001) and external rotation (p = 0.02). Chondrolysis was present in 11.3% of the hips tested. One case of pseudoarthrosis with aseptic capital necrosis was presented. There was no significant variation between age and chondrolysis (p = 1.00).Significant variation between gender/non-white patients versus chondrolysis (p = 0.031) and (p = 0.037), respectively was verified. No causal association between plaster cast and chondrolysis was observed (p = 0.60). In regard to the symptomatology group and the slip degree versus chondrolysis, the p value was not statistically

  2. How well do surface offsets represent earthquake slip at depth?

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

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

    PubMed

    Kim, In-Ju; Nagata, Hisao

    2008-01-01

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

  4. How Orogen-scale Exhumed Strike-slip Faults Initiate

    NASA Astrophysics Data System (ADS)

    Cao, S.; Neubauer, F.

    2015-12-01

    Orogen-scale strike-slip faults present one the most important geodynamic processes affecting the lithosphere-asthenosphere system. In specific subtypes, faulting is virtually initiated along hot-to-cool boundaries, e.g. at such of hot granite intrusions or metamorphic core complexes to cool country rocks. Such fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust and are stacked within each other ("telescoping"). Exhumation of rocks is, therefore, a common feature of such strike-slip faults implying major transtensive and/or transpressive processes accompanying pure strike-slip motion. The hot-to-cool thermal structure across the fault zone significantly influences the physical fault rock properties. One major question is how and where a major strike-slip initiates and further development. Here, we propose a model in which major continental exhumed strike-slip faults potentially evolve along rheologically weak zones such as plutons or margins of metamorphic complexes. As an example, we propose a model for the Ailao Shan-Red River (ASRR) fault, SE Asia, which initiated along the edge of a plutonic belt and evolved in response to India-Asia collision with four tectonic phases.

  5. Biodegradable polymers: Wall slip, melt fracture, and processing aids

    NASA Astrophysics Data System (ADS)

    Othman, Norhayani; Noroozi, Nazbanoo; Jazrawi, Bashar; Mehrkhodavandi, Parisa; Schafer, Laurel; Hatzikiriakos, Savvas George

    2015-04-01

    The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) and poly(ɛ-caprolactone), (PCLs) have been investigated. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight consistent with wall slip data reported in the literature for other systems. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Similarly, sharkskin and gross melt fracture was observed for the case of PCLs depending on the molecular characteristics of the resins and the geometrical details of the capillary dies. It was also found that the addition of a small amount of PCL (typically 0.5 wt.%) into the PLA and vice versa is effective in eliminating and delaying the onset of melt fracture to higher shear rates in the capillary extrusion of PLA and PCL respectively. This is due to significant interfacial slip that occurs in the presence of PCL or PLA as well as to the immiscibility of the PLA/PCL blend system at all compositions.

  6. Individualized menu slips improve the accuracy of patient food trays.

    PubMed

    Myers, E F; Knoz, S A; Gregoire, M B

    1991-11-01

    We evaluated the effect of five menu slip formats on worker preference and accuracy of food trays in a simulated hospital tray line. Menu slip formats were either individualized or preprinted, and various combinations of color coding, large type, and bold print were used to code the type of diet and the menu choices to be placed on the tray. Student volunteers who had not worked in hospital foodservice were used as tray line workers to reduce the possibility of prior preference for a menu slip format. Results indicate that menu slip format significantly affects both worker preference and the accuracy of assembled food trays. Errors were significantly lower with individualized formats that identified menu selections in bold print and type of diet in either large type or colored ink. The highest error rate was found with preprinted formats. An individualized menu slip that identified menu selections and diet orders with large type and bold print received the highest worker preference rating and resulted in the most accurate tray assembly. PMID:1939982

  7. Motion of a Deformed Sphere with Slip in Creeping Flows

    NASA Astrophysics Data System (ADS)

    Benard, Andre; Jia, Liping; Petty, Charles

    2004-11-01

    An analytical solution for the motion of a slightly deformed sphere in creeping flows with the assumption of slip on the particle surface is presented. Explicit expressions are obtained for the hydrodynamic force and torque exerted by the fluid on the deformed sphere. A perturbation method, based on previous work done by Brenner [1964] and Lamb[1945], is used to solve for the motion of a fluid influenced by the presence of a deformed sphere. Slip is assumed at the surface of the particle. Hydrodynamic force and torque exerted by the fluid on the deformed sphere are expressed explicitly for a translational and rotational deformed sphere. The equation governing the motion and orientation of a spheroid induced by homogenous flows is also presented. This evolution equation for the orientation of the spheroid is similar to the equation derived by Jeffery [1922]. Solutions of this equation show that the period of rotation of the particle with slip is longer than for the same particle without slip. Furthermore, when the slip coefficient is sufficiently low, the particle rotates to a fixed angle that corresponds to a quasi-steady state in the flow. REFERENCES Brenner, H. 1964 The Stokes resistance of a slightly deformed sphere. Chemical Engineering Science 19, 519-539 Jeffery, G.B.1922 The motion of ellipsoidal particles immersed in a viscous fluid. Proc. Soc. Lond. Math., 102, 161-179 Lamb, H. 1945 Hydrodynamics, sixth version, Dover, New York, U.S.A

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  9. Using fault displacement and slip tendency to estimate stress states

    NASA Astrophysics Data System (ADS)

    Morris, Alan P.; Ferrill, David A.; McGinnis, Ronald N.

    2016-02-01

    We suggest that faults in high slip tendency orientations tend to develop larger displacements than other faults. Consequently, faults that accumulate larger displacements are more likely to be reliable indicators of the longer term stress field and should be weighted accordingly in paleostress estimation. Application of a stress inversion technique that uses slip tendency analyses and fault displacements to interpret populations of coherent normal faults within the Balcones Fault System of south-central Texas provides stress estimates that are consistent with established regional stress analyses. Although the method does not require measurement of slip directions, these data, where available, and sensitivity analyses of the angular mismatch between measured slip directions and those predicted by inverted stress states provide high confidence in the stress estimates generated using slip tendency analyses. Close inspection of the fault orientation and displacement data further indicates that subpopulations of faults with orientations different from the regional pattern have formed in response to stress perturbations generated by displacement gradients on an adjacent seismic scale fault.

  10. Stokes flow in a pipe with distributed regions of slip

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Stone, Howard A.

    2002-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Guichard, Wiebke

    2011-03-01

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

  12. Path Following with Slip Compensation for a Mars Rover

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  13. Recognition and repair of the slipped rectus muscle.

    PubMed

    Plager, D A; Parks, M M

    1988-01-01

    Since the first description of the slipped muscle as a complication of strabismus surgery in 1979, the distinctions between it and the lost muscle have become blurred both in the literature and in general understanding. Sixtytwo slipped muscles in 52 consecutive patients were reviewed in an effort to more fully describe this Important and often unrecognized entity. The range of clinical presentation of slipped muscle is large: from the immediate large postoperative over- or undercorrection with absent duction, to the gradual moderate deviation with subtly reduced excursion. The auctions provided by the slipped muscles ranged from complete absence to almost normal, with an average of 19° excursion beyond the midline. At surgery, recognizing the empty muscle capsule attached to the sclera with the tendon slipped posteriorly within it is imperative for its repair. Recognition is facilitated by suspecting it from clinical findings. Correction of the motility defect requires advancement of the muscle tissue and not just its empty capsule. Slippage can probably be prevented by using a surgical technique, which firmly locks the suture to the tendon and not just to the muscle capsule. PMID:24880054

  14. Size Distribution of Slip Values in Finite-Fault Rupture Models

    NASA Astrophysics Data System (ADS)

    Thingbaijam, K. K. S.; Mai, P. M.

    2014-12-01

    Understanding statistical properties of earthquake sources is crucial for proper ground-motion predictions. We investigate the size distribution of slip values as imaged by finite-fault rupture models. Our analysis utilizes rupture models from the SRCMOD database (http://equake-rc.info/srcmod). To overcome the limitation of variable spatial sampling across different models, we consider combined areas of fault-rupture corresponding to different slip bins. The slip values in each rupture model are binned according to fractions of the overall maximum slip. We refer to the rupture area occupied by a specified slip bin as slip-area. To eliminate possible spurious small slip at the fault edge, we compute the effective source dimensions from the slip distribution, accounting for sub-fault size, location of slip-asperities, and surface rupture (if present). This procedure includes trimming the model to the smallest dimensions that accommodate the autocorrelation width of the slip distribution (Mai and Beroza, 2000). We modify the trimming process to not affect any large slip asperity (u ≥ umax/3) where u and umax denote slip and maximum slip value. In order to look beyond individual models, we develop scaling relationships between seismic moment and slip-areas. These relationships are, thereafter, employed to derive average tail distribution (or exceedance) of the slip values. Our regression analysis reveals that self-similar source scaling holds for dip-slip events while scale invariance breaks down for large strike-slip events. We find that the tail distributions of the slip values can be described by stretched-exponential functions, with the averaged distribution close to exponential. This characterization of the slip distribution agrees with the source scaling laws, and will be useful in generating realistic earthquake rupture scenarios for ground-motion modeling.

  15. Intense interface seismicity triggered by a shallow slow-slip event in the Central-Ecuador subduction zone

    NASA Astrophysics Data System (ADS)

    Vallee, M.; Nocquet, J.; Battaglia, J.; Font, Y.; Segovia, M.; Regnier, M. M.; Mothes, P. A.; Jarrín, P.; Cisneros, D.; Vaca, S.; Yepes, H. A.; Martin, X.; Béthoux, N.; Chlieh, M.

    2013-12-01

    have been regularly observed (1977, 1998, 2002, 2005). These swarms have likely been triggered by large magnitude slow-slip events. Joint observations of the geodetic displacement and of the seismicity rate at La Plata Island (ISPT station) during the 2010 SSE. (Red) Number of seismic events detected over 2 hours sessions for an LTA/STA ratio higher than 6.0. (Grey dots) East displacement recorded by the GPS station, calculated every 6 hours.

  16. Sustainable Chemistry, the Spinning Tube-in-Tube (STT(R)) Reactor and GREENSCOPE: Innovation and Industrial Partnerships

    EPA Science Inventory

    The chemical industry faces environmental, social and health challenges that are common across all economic sectors. From worker exposure to toxic substances, to product design and use, to the cost and handling of waste disposal, the industry must overcome numerous complex hurdle...

  17. What causes an icy fault to slip? Investigating strike-slip failure conditions on Ganymede at Dardanus and Tiamat Sulcus.

    NASA Astrophysics Data System (ADS)

    Cameron, M. E.; Smith-Konter, B. R.; Burkhard, L. M.; Collins, G. C.; Seifert, F.; Pappalardo, R. T.

    2015-12-01

    Ganymede exhibits two geologically distinct terrains known as dark and light (grooved) terrain. The mechanism for a transition from dark to light terrain remains unclear; however, inferences of strike-slip faulting and distributed shear zones suggest that strike-slip tectonism may be important to the structural development of Ganymede's surface and in this transition. Here we investigate the role of tidal stresses on Ganymede in the formation and evolution of strike-slip structures in both dark and grooved terrains. Using numerical code SatStress, we calculate both diurnal and non-synchronous rotation (NSR) tidal stresses at Ganymede's surface. Specifically, we investigate the role of fault friction and orbital eccentricity in the development of ~45 km of right-lateral offset at Dardanus Sulcus and a possible case of <10 km of right-lateral offset at Tiamat Sulcus. We compute Coulomb failure conditions for these target fractures and consider tidal stress scenarios for both present eccentricity (0.0013) and possible past high (~0.05) eccentricity of Ganymede. We find that while diurnal stresses are not large enough to support strike-slip failure at present or past eccentricities, models that include both diurnal and NSR stress readily generate shear and normal stress magnitudes that could give rise to shear failure. Results for a past high eccentricity assuming a low coefficient of friction (μf = 0.2) suggest shear failure is possible down to depths of 1-2 km along both Dardanus and Tiamat. For a high coefficient of friction (μf = 0.6), failure is limited to about 1 km depth at Dardanus and Tiamat, although confined to small episodic slip windows for the latter. Moreover, our models predict a right-lateral sense of slip, in agreement with inferred offset observed at both regions. Based on these results, we infer that past shear failure on Ganymede is possible when NSR is a driving stress mechanism. We complement this study with a detailed morphological mapping of

  18. Does the Euler Disk slip during its motion?

    NASA Astrophysics Data System (ADS)

    Petrie, D.; Hunt, J. L.; Gray, C. G.

    2002-10-01

    The motion of a disk that is spun on a smooth flat surface slowly damps out due to friction. To help identify the nature of the friction, we test experimentally whether the disk slips during its motion. We find that, at least during the early stages, the disk rolls without slipping, thus ruling out sliding friction as the cause of the damping. Together with the results of the experiments of van der Engh et al. that rule out air friction, our results establish that rolling friction is mainly responsible for the damping in the early stages of the motion. Student projects are suggested that could establish whether our conclusion of rolling without slipping holds for the later stages of the motion.

  19. Surface-slip equations for multicomponent nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, R. N.; Scott, C. D.; Moss, J. N.

    1985-01-01

    Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds number, high-altitude flight regime of a space vehicle. The equations are obtained from closed form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities were obtained in a form which can be employed in flowfield computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate, species-concentration boundary condition for a multicomponent mixture in absence of slip.

  20. Shearing flows of frictionless spheres over bumpy planes: slip velocity

    NASA Astrophysics Data System (ADS)

    Berzi, Diego; Vescovi, Dalila

    2016-05-01

    Boundary conditions for the slip velocity of inelastic, frictionless spheres interacting with bumpy walls are derived via discrete element method simulations of Couette granular flows. The bumpiness is created by gluing spheres identical to those flowing in a regular hexagonal array to a flat plane. Depending on the particle inelasticity and bumpiness, the characteristics of the flow range from simple shearing to plug flow. At low bumpiness—small distance between the wall-particles—the ratio of particle shear stress to pressure is a non-linear function of the slip velocity and presents a maximum. At high bumpiness, the bumpy plane behaves as a flat, frictional surface and the stress ratio saturates to a constant value for large slip velocity.

  1. ETS and tidal stressing: Fault weakening after main slip pulse

    NASA Astrophysics Data System (ADS)

    Houston, H.

    2013-12-01

    Time-varying stresses from solid Earth tides and ocean loading influence slow slip (Hawthorne and Rubin, 2010) and, consequently, the frequency of occurrence and intensity of tremor during ETS episodes (Rubinstein et al., 2008). This relationship can illuminate changes in the mechanical response of the rupture surfaces(s) during slip in ETS. I compare the influence of tidal loading when and after the propagating ETS slip front (estimated by tremor density in time) ruptures the fault at a given spot. Using estimates of slip fronts that I derived from tremor locations, I divide ETS tremor into two groups: that occurring within a day of the start of the inferred slip front and that occurring over several days thereafter. The tremor catalog used contains 50K waveform cross-correlation locations of tremor in 7 large ETS in northern Cascadia between 2005 and 2012. I calculate normal, shear and volumetric stresses due to the Earth and ocean tides at numerous locations on the inferred rupture plane of the ETS following the method of Hawthorne and Rubin (2010). The Coulomb stress increment at each tremor time and location is compared with tremor occurrence for the two groups of tremor. Unreasonable results appear if the effective frictional coefficient mu > 0.2, and results are most 'reasonable' when mu is very near or equal to zero. Following passage of the main slip pulse, tremor generation is notably more sensitive to tidal stressing. One kPa of encouraging tidal Coulomb stress boosts the occurrence of tremor after the main slip pulse by about 50% above the average value, while the same amount of discouraging stress decreases the occurrence of such tremor by a similar factor. The greater the encouraging or discouraging stress, the greater the effect. In contrast, tremor in the main slip pulse is much less affected by positive or negative tidal stresses. I interpret the greater sensitivity to tidal stressing of the tremor after the main slip pulse as a measure of the

  2. Surface-slip equations for multicomponent, nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, Roop N.; Scott, Carl D.; Moss, James N.; Goglia, Gene

    1985-01-01

    Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip.

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

    DOEpatents

    Cleveland, Joe R.

    1997-01-01

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

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

    DOEpatents

    Cleveland, J.R.

    1997-03-18

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

  5. Dynamically triggered slip and sustained fault gouge instability associated with unique slip behavior under laboratory shear conditions

    NASA Astrophysics Data System (ADS)

    Johnson, P. A.; Carmeliet, J.; Savage, H. M.; Scuderi, M.; Carpenter, B. M.; Guyer, R. A.; Daub, E. G.; Marone, C.

    2015-12-01

    We investigate dynamic-wave triggered slip under laboratory shear conditions. The experiment is comprised of a 3-block system containing two gouge layers composed of glass beads and held in place by a fixed load in a bi-axial configuration. When the system is sheared under steady state conditions at loads from 3-8 MPa, stick-slip exhibiting a characteristic recurrence time is observed. Under these load conditions, we find that shear failure may be instantaneously triggered by a brief dynamical wave if the system is in a critical shear-stress state, near failure. Dynamic triggering is only observed when the dynamic wave amplitude exceeds strains of 10^(-7). Following triggering, the gouge material remains in an unstable state for long periods of time as manifest by unique slip characteristics not observed during spontaneous events: the measured physical characteristics—the gouge material strength recovery, the gouge layer thickness, the gouge shear modulus and the stick-slip recurrence time recover over many stick-slip cycles following triggering. This work suggests that faults must be critically stressed to trigger under dynamic conditions and that the recovery process following a dynamically triggered event differs from the recovery following a spontaneous event.

  6. Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Hartwell, Stephen R.; Dartnell, Peter

    2014-01-01

    The Hosgri fault is the southern part of the regional Hosgri–San Gregorio dextral strike‐slip fault system, which extends primarily in the offshore for about 400 km in central California. Between Morro Bay and San Simeon, high‐resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by an ∼265  m wide slope interpreted as the shoreface of a latest Pleistocene sand spit. This sand spit crossed an embayment and connected a western fault‐bounded bedrock peninsula and an eastern bedrock highland, a paleogeography resembling modern coastal geomorphology along the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6±0.9  mm/yr, considered a minimum rate for the Hosgri given the presence of an active western strand. This slip rate indicates that the Hosgri system takes up the largest share of the strike‐slip fault budget and is the most active strike‐slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high‐resolution bathymetry in characterization of active offshore faults.

  7. Probabilistic estimates of surface slip including the effects of creep and afterslip

    NASA Astrophysics Data System (ADS)

    Aagaard, B.; Lienkaemper, J. J.; Schwartz, D. P.

    2009-12-01

    We develop a methodology for probabilistic estimates of coseismic and postseismic surface slip for scenario earthquakes that explicitly includes the effects of creep and afterslip. We apply Monte Carlo simulations to include uncertainty from the Hanks and Bakun (2008) magnitude-area relation, distribution of slip, and the effect of creep on coseismic slip. We extract coseismic surface slip from a suite of kinematic slip models that are constructed following the same approach we used in kinematic rupture models for ground motion modeling of scenario events on the Hayward Fault (Aagaard, et al., 2008), with additional calibration for coseismic surface slip using empirical regressions and observations provided by Wells and Coppersmith (1994). The kinematic slip models include variation in earthquake magnitude, rupture length, slip distribution, and reduce the coseismic slip in creeping patches delineated by Funning et al. (2007). Postseismic slip in our analysis is based upon empirical regressions developed from afterslip measurements from the 1987 magnitude 6.6 Superstition Hills earthquake in southern California. We apply this methodology to a location on the Hayward fault in the San Francisco Bay area to characterize the coseismic and postseismic slip expected for magnitude 6.5-7.1 earthquakes. We find that creep decreases the expected coseismic slip and substantial afterslip may occur in the first few days following an earthquake. This analysis provides a significantly different temporal estimate of surface slip compared with conventional probabilistic estimates that ignore the effects of creep and postseismic slip.

  8. Volcano instability induced by strike-slip faulting

    NASA Astrophysics Data System (ADS)

    Lagmay, A. M. F.; van Wyk de Vries, B.; Kerle, N.; Pyle, D. M.

    2000-09-01

    Analogue sand cone experiments were conducted to study instability generated on volcanic cones by basal strike-slip movement. The results of the analogue models demonstrate that edifice instability may be generated when strike-slip faults underlying a volcano move as a result of tectonic adjustment. This instability occurs on flanks of the volcano above the strike-slip shear. On the surface of the volcano this appears as a pair of sigmoids composed of one reverse and one normal fault. In the interior of the cone the faults form a flower structure. Two destabilised regions are created on the cone flanks between the traces of the sigmoidal faults. Bulging, intense fracturing and landsliding characterise these unstable flanks. Additional analogue experiments conducted to model magmatic intrusion show that fractures and faults developed within the volcanic cone due to basal strike-slip motions strongly control the path of the intruding magma. Intrusion is diverted towards the areas where previous development of reverse and normal faults have occurred, thus causing further instability. We compare our model results to two examples of volcanoes on strike-slip faults: Iriga volcano (Philippines), which underwent non-magmatic collapse, and Mount St. Helens (USA), where a cryptodome was emplaced prior to failure. In the analogue and natural examples, the direction of collapse takes place roughly parallel to the orientation of the underlying shear. The model presented proposes one mechanism for strike-parallel breaching of volcanoes, recently recognised as a common failure direction of volcanoes found in regions with transcurrent and transtensional deformation. The recognition of the effect of basal shearing on volcano stability enables prediction of the likely direction of eventual flank failure in volcanoes overlying strike-slip faults.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Phase-field slip-line theory of plasticity

    NASA Astrophysics Data System (ADS)

    Freddi, Francesco; Royer-Carfagni, Gianni

    2016-09-01

    A variational approach to determine the deformation of an ideally plastic substance is proposed by solving a sequence of energy minimization problems under proper conditions to account for the irreversible character of plasticity. The flow is driven by the local transformation of elastic strain energy into plastic work on slip surfaces, once that a certain energetic barrier for slip activation has been overcome. The distinction of the elastic strain energy into spherical and deviatoric parts is used to incorporate in the model the idea of von Mises plasticity and isochoric plastic strain. This is a "phase field model" because the matching condition at the slip interfaces is substituted by the evolution of an auxiliary phase field that, similar to a damage field, is unitary on the elastic phase and null on the yielded phase. The slip lines diffuse in bands, whose width depends upon a material length-scale parameter. Numerical experiments on representative problems in plane strain give solutions with noteworthy similarities with the results from classical slip-line field theory, but the proposed model is much richer because, accounting for elastic deformations, it can describe the formation of slip bands at the local level, which can nucleate, propagate, widen and diffuse by varying the boundary conditions. In particular, the solution for a long pipe under internal pressure is very different from the one obtainable from the classical macroscopic theory of plasticity. For this case, the location of the plastic bands may be an insight to explain the premature failures that are sometimes encountered during the manufacturing process. This practical example enhances the importance of this new theory based on the mathematical sciences.

  11. On the transient behavior of frictional melt during seismic slip

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; Mosca, P.; Giberti, G.; di Toro, G.; Hirose, T.; Shimamoto, T.

    2010-10-01

    In a recent work on the problem of sliding surfaces under the presence of frictional melt (applying in particular to earthquake fault dynamics), we derived from first principles an expression for the steady state friction compatible with experimental observations. Building on the expressions of heat and mass balance obtained in the above study for this particular case of Stefan problem (phase transition with a migrating boundary), we propose here an extension providing a full time-dependent solution (including the weakening transient after pervasive melting has started, the effect of eventual steps in velocity, and the final decelerating phase). A system of coupled equations is derived and solved numerically. The resulting transient friction and wear evolution yield a satisfactory fit (1) with experiments performed under variable sliding velocities (0.9-2 m s-1) and different normal stresses (0.5-20 MPa) for various rock types and (2) with estimates of slip weakening obtained from observations on ancient seismogenic faults that host pseudotachylite (solidified melt). The model allows us to extrapolate the experimentally observed frictional behavior to large normal stresses representative of the seismogenic Earth crust (up to 200 MPa), high slip rates (up to 9 m s-1), and cases where melt extrusion is negligible. Though weakening distance and peak stress vary widely, the net breakdown energy appears to be essentially independent of either slip velocity or normal stress. In addition, the response to earthquakelike slip can be simulated, showing a rapid friction recovery when slip rate drops. We discuss the properties of energy dissipation, transient duration, velocity weakening, restrengthening in the decelerating final slip phase, and the implications for earthquake source dynamics.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Zu, Ximeng; Reches, Zeev

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  15. Coulombic wall slip of concentrated soft-particle suspensions

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  16. Slip Distribution of the 2001 West India Earthquake

    NASA Astrophysics Data System (ADS)

    Mori, J.; Sato, T.; Negishi, H.

    2001-12-01

    We used the orientation and size of the fault determined from our aftershock results to carry out an inversion of teleseismic data for the slip distribution of the 2001 West India earthquake. Previous inversions for this earthquake have been done by but these solutions did not use the constraints on the fault geometry that are now available. Choosing the correct fault plane from the two nodal planes of the focal mechanism and limiting the mainshock source area to the size of the aftershock region affects the slip distribution. We used 19 teleseismic P waveforms which were well distributed in azimuth in a finite-fault inversion on a grid of 80 subfaults. Since the observed waveforms look similar at all azimuths, we decided that there was not much time resolution and used only one time window. The results of the inversion for the various rupture velocities tested, did not show significant differences. We show the results for a rupture velocity of 2.9 km per sec. The results of the inversion show that the largest area of slip is close to hypocenter. This asperity is about 10 km x 20 km with a maximum slip of about 10 meters. The area of large slip in the region of the hypocenter corresponds closely to the area of most severe damage in the villages east of Bhuj. This area probably experienced very strong shaking from the rupture of the asperity. Bhuj, is located more than 30 km west from the closest portion of the fault and probably experience somewhat lower levels of ground motions, as seen in the intensity distribution. The character of the slip distribution appears different from other shallow earthquakes of equal size. The area of the fault is small for a Mw7.7 event. Comparing the slip distribution of the 2001 West India earthquake to the similarly sized (Mw7.7) 1999 Taiwan earthquake. The Taiwan earthquake is spread out over a larger area and shows a more complicated slip distribution. These difference can also be seen in the teleseismic waveforms. The India

  17. Temperature dependence of atomic-scale stick-slip friction.

    PubMed

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

    2010-06-25

    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

  18. Rupture of multiple catch-slip bonds: Two-state two-pathway catch-slip bonds.

    PubMed

    Gupta, V K

    2013-11-01

    We performed Monte Carlo simulation of the detachment of a polymorphonuclear (PMN) leukocyte immersed in a Newtonian fluid and adhered to a substrate by multiple catch-slip bonds. We found that at certain loading rates the interplay of multiple catch-slip bonds leads to a bimodal distribution of the bond rupture force. We also found that the low force peak in these bond rupture force distributions switches to a high force peak with a gradual increase in the loading rate. These trends in the bond rupture force distributions are characteristics of two-state systems. Consequently, though individual catch-slip bonds follow one-state two-pathway energy landscape, their interplay mimics a two-state two-pathway energy landscape. PMID:24272665

  19. 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)

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

    2010-12-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

  1. Slip sense inversion on active strike-slip faults in southwest Japan and its implications for Cenozoic tectonic evolution

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2004-05-01

    Analyses of deflected river channels, offset of basement rocks, and fault rock structures reveal that slip sense inversion occurred on major active strike-slip faults in southwest Japan such as the Yamasaki and Mitoke fault zones and the Median Tectonic Line (MTL). Along the Yamasaki and Mitoke fault zones, small-size rivers cutting shallowly mountain slopes and Quaternary terraces have been deflected sinistrally, whereas large-size rivers which deeply incised into the Mio-Pliocene elevated peneplains show no systematically sinistral offset or complicated hairpin-shaped deflection. When the sinistral offsets accumulated on the small-size rivers are restored, the large-size rivers show residual dextral deflections. This dextral offset sense is consistent with that recorded in the pre-Cenozoic basement rocks. S-C fabrics of fault gouge and breccia zone developed in the active fault zones show sinistral shear sense compatible with earthquake focal mechanisms, whereas those of the foliated cataclasite indicate a dextral shear sense. These observations show that the sinistral strike-slip shear fabrics were overprinted on dextral ones which formed during a previous deformation phase. Similar topographic and geologic features are observed along the MTL in the central-eastern part of the Kii Peninsula. Based on these geomorphological and geological data, we infer that the slip sense inversion occurred in the period between the late Tertiary and mid-Quaternary period. This strike-slip inversion might result from the plate rearrangement consequent to the mid-Miocene Japan Sea opening event. This multidisciplinary study gives insight into how active strike-slip fault might evolves with time.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. The influence of slip velocity and temperature on permeability during and after high-velocity fault slip

    NASA Astrophysics Data System (ADS)

    Tanikawa, W.; Mukoyoshi, H.; Tadai, O.; Hirose, T.; Lin, W.

    2011-12-01

    Fluid transport properties in fault zones play an important role in dynamic processes during large earthquakes. If the permeability in a fault zone is low, high pore-fluid pressures caused by thermal pressurization (Sibson, 1973) or shear-induced compaction (Blanpied et al., 1992) can lead to an apparent reduction of fault strength. Changes in porosity and permeability of fault rocks within a fault zone during earthquakes and the subsequent progressive recovery of these properties may have a large influence on earthquake recurrence (Sleep and Blanpied, 1992). A rotary shear apparatus was used to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone and granite cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with an increase of friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity tests but recovered to exceed them after high-velocity tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different. References Blanpied, M.L., Lockner, D.A., Byerlee, J.D., 1992. An earthquake mechanism

  4. Resonant slow fault slip in subduction zones forced by climatic load stress.

    PubMed

    Lowry, Anthony R

    2006-08-17

    Global Positioning System (GPS) measurements at subduction plate boundaries often record fault movements similar to earthquakes but much slower, occurring over timescales of approximately 1 week to approximately 1 year. These 'slow slip events' have been observed in Japan, Cascadia, Mexico, Alaska and New Zealand. The phenomenon is poorly understood, but several observations hint at the processes underlying slow slip. Although slip itself is silent, seismic instruments often record coincident low-amplitude tremor in a narrow (1-5 cycles per second) frequency range. Also, modelling of GPS data and estimates of tremor location indicate that slip focuses near the transition from unstable ('stick-slip') to stable friction at the deep limit of the earthquake-producing seismogenic zone. Perhaps most intriguingly, slow slip is periodic at several locations, with recurrence varying from 6 to 18 months depending on which subduction zone (or even segment) is examined. Here I show that such periodic slow fault slip may be a resonant response to climate-driven stress perturbations. Fault slip resonance helps to explain why slip events are periodic, why periods differ from place to place, and why slip focuses near the base of the seismogenic zone. Resonant slip should initiate within the rupture zone of future great earthquakes, suggesting that slow slip may illuminate fault properties that control earthquake slip. PMID:16915286

  5. Fast rupture propagation for large strike-slip earthquakes

    NASA Astrophysics Data System (ADS)

    Wang, Dun; Mori, Jim; Koketsu, Kazuki

    2016-04-01

    Studying rupture speeds of shallow earthquakes is of broad interest because it has a large effect on the strong near-field shaking that causes damage during earthquakes, and it is an important parameter that reflects stress levels and energy on a slipping fault. However, resolving rupture speed is difficult in standard waveform inversion methods due to limited near-field observations and the tradeoff between rupture speed and fault size for teleseismic observations. Here we applied back-projection methods to estimate the rupture speeds of 15 Mw ≥ 7.8 dip-slip and 8 Mw ≥ 7.5 strike-slip earthquakes for which direct P waves are well recorded in Japan on Hi-net, or in North America on USArray. We found that all strike-slip events had very fast average rupture speeds of 3.0-5.0 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.

  6. Unified formulation for analysis of slopes with general slip surface

    SciTech Connect

    Espinoza, R.D.; Bourdeau, P.L. . School of Civil Engineering); Muhunthan, B. . Dept. of Civil and Environmental Engineering)

    1994-07-01

    The general availability of computers has provided efficient means of assessing the stability of slopes using several analytical methods. However, the increased use of computers coupled with a lack of unified presentation of the various methods sometimes leads to conflicting results. It is shown that the current analytical methods can be grouped into three categories based on the hypotheses used to describe the internal forces, namely: (1) the direction of the internal forces; (2) the height of the line of thrust; and (3) the shape of the distribution function of the internal shear forces. An analytical framework incorporating this idea is presented to facilitate and unify slope stability analysis with general slip surfaces. The study is a generalization of earlier work performed by Espinoza et al. for circular slip surfaces. The framework incorporates most current methods of analysis. The analytical model is implemented in a computer program. The program was used to study several case examples. On this basis, key issues associated with the influence of the internal shear forces on the factor of safety, for both circular and general slip failure surfaces, are discussed. It appears that for circular failure surfaces, even with heterogeneous soil stratigraphy the factor of safety is not affected by the choice of a particular hypothesis. On the contrary, for general slip surfaces this choice may significantly affect the results.

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

    NASA Technical Reports Server (NTRS)

    Froude, W

    1920-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  10. Phase-slip interferometry for precision force measurements.

    PubMed

    Tuchman, Ari K; Kasevich, Mark A

    2009-09-25

    We demonstrate a novel atom interferometric force sensor based on phase slips in the dynamic evolution of a squeezed-state array of degenerate ;{87}Rb atoms confined in a one-dimensional optical lattice. The truncated Wigner approximation is used to model our observations. PMID:19905495

  11. Phase-Slip Interferometry for Precision Force Measurements

    SciTech Connect

    Tuchman, Ari K.; Kasevich, Mark A.

    2009-09-25

    We demonstrate a novel atom interferometric force sensor based on phase slips in the dynamic evolution of a squeezed-state array of degenerate {sup 87}Rb atoms confined in a one-dimensional optical lattice. The truncated Wigner approximation is used to model our observations.

  12. Effects of slip on oscillating fractionalized Maxwell fluid

    NASA Astrophysics Data System (ADS)

    Jamil, Muhammad

    2016-03-01

    The flow of an incompressible fractionalized Maxwell fluid induced by an oscillating plate has been studied, where the no-slip assumption between the wall and the fluid is no longer valid. The solutions obtained for the velocity field and the associated shear stress, written in terms of H-functions, using discrete Laplace transform, satisfy all imposed initial and boundary conditions. The no-slip contributions, that appeared in the general solutions, as expected, tend to zero when slip parameter θ → 0. Furthermore, the solutions for ordinary Maxwell and Newtonian fluids, performing the same motion, are obtained as limiting cases of general solutions. The solutions for fractionalized and ordinary Maxwell fluids for noslip condition also obtained as a special cases and they are similar to the solutions of classical Stokes' first problem of fractionalized and ordinary Maxwell fluid, if oscillating parameter ω = 0. Finally, the influence of the material, slip and the fractional parameters on the fluid motion, as well as a comparison among fractionalized Maxwell, ordinary Maxwell and Newtonian fluids is also analyzed by graphical illustrations.

  13. Break-Even Point for a Proof Slip Operation

    ERIC Educational Resources Information Center

    Anderson, James F.

    1972-01-01

    Break-even analysis is applied to determine what magnitude of titles added per year is sufficient to utilize economically Library of Congress proof slips and a Xerox 914 copying machine in the cataloging operation of a library. A formula is derived, and an example of its use is given. (1 reference) (Author/SJ)

  14. Adhesive slip process between a carbon nanotube and a substrate

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Chiao; McGruer, Nicol E.; Adams, George G.

    2013-05-01

    Since their discovery in 1991, carbon nanotubes (CNTs) have been attractive components for nanoelectromechanical (NEM) devices because of their excellent mechanical and electrical properties. Several CNT-based NEM devices have been reported. Experimental investigations have discovered that the force required for a CNT to slip on a SiO2 substrate is almost constant in the range of contact lengths from 140 to 246 nm and increases with the contact length for greater lengths. This study develops a theory based on the continuum mechanics to explain this observed phenomenon. The critical force needed to cause the CNT to slip over the whole substrate is determined by applying a beam theory which includes the bending, shear, and axial deformations of the CNT. At the stick-slip transition, the work of adhesion contributes a concentrated force and a concentrated moment to produce discontinuities in the internal forces and moments of the CNT. The modelling results obtained here provide the external force required for complete slip versus a dimensionless parameter related to the shear stress and the contact length. A comparison of the modelling result and the experimental data from the literature shows good agreement.

  15. Micro-Vibration-Based Slip Detection in Tactile Force Sensors

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Blanchard, Danny; Ligrani, Phil

    2007-10-01

    Displacements of gas flows, both with and without slip, are described for rotation-induced flows in a C-shaped fluid chamber passage formed between a rotating disk and a stationary surface, with a height h of 13.3 µm. Included are accommodation coefficients for the stationary smooth wall, smooth disk surface, medium rough disk surface rough disk surface. Flow rate and pressure rise magnitudes deduced using these accommodation coefficients, and simplified forms of the Navier-Stokes equations, are consistent with experimental data over rotational speeds of 200-1200 rpm, pressure increases of 0-400 Pa, net flow rates of 0-100 µl min-1, Knudsen numbers of 0.0056 and 0.0158, average roughness magnitudes of 0.01- 1.1 µm and working fluids of air and helium. All situations investigated consider a large roughness size compared to the molecular mean free path. For a particular normalized fluid chamber pressure rise P*, the normalized volumetric flow rate Q* with slip is generally less than the value with no slip. Lower P* magnitudes are also generally present at a particular value of Q*, in general, as the working fluid is changed from air to helium and the Knudsen number increases. The slopes of dimensional pressure variations with rotational speed decrease as disk surface roughness levels increase, as values of the accommodation coefficient decrease and, thus, as near-wall slip velocity magnitudes increase.

  17. Wall slip across the jamming transition of soft thermoresponsive particles

    NASA Astrophysics Data System (ADS)

    Divoux, Thibaut; Lapeyre, Véronique; Ravaine, Valérie; Manneville, Sébastien

    2015-12-01

    Flows of suspensions are often affected by wall slip, that is, the fluid velocity vf in the vicinity of a boundary differs from the wall velocity vw due to the presence of a lubrication layer. While the slip velocity vs=|vf-vw| robustly scales linearly with the stress σ at the wall in dilute suspensions, there is no consensus regarding denser suspensions that are sheared in the bulk, for which slip velocities have been reported to scale as a vs∝σp with exponents p inconsistently ranging between 0 and 2. Here we focus on a suspension of soft thermoresponsive particles and show that vs actually scales as a power law of the viscous stress σ -σc , where σc denotes the yield stress of the bulk material. By tuning the temperature across the jamming transition, we further demonstrate that this scaling holds true over a large range of packing fractions ϕ on both sides of the jamming point and that the exponent p increases continuously with ϕ , from p =1 in the case of dilute suspensions to p =2 for jammed assemblies. These results allow us to successfully revisit inconsistent data from the literature and pave the way for a continuous description of wall slip above and below jamming.

  18. Experimental Investigations Of Failure Mechanisms Associated With Slow Slip Events

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Tamarkin, T.

    2010-12-01

    Slow slip events such as very low frequency earthquakes (VLFEs) are detected in the Nankai accretionary prism [Ito and Obara, 2006]. It is proposed that high pore fluid pressure weakens the out-of-sequence-thrusts and mega-splay faults by reducing effective normal stress on the fault plane and consequently generates slip instability producing low stress drop VLFEs. However, the frictional behaviors and failure mechanisms associated with reduction of effective normal stress are not well understood. In this study, we conducted frictional experiments on porous sedimentary rocks with a saw-cut. Sediments with different clay content from NantroSEIZE drilling project ODP Legs 315, 316, and 322 are used as fault gouge. A new triaxial loading configuration was designed to investigate the effect of high pore pressure on frictional instability and failure modes. During the deformation experiments, samples were subjected to constant axial stress and decreasing radial stresses. Distinguishing from the conventional loading configuration in which mean stress increases during deformation, with the alternative loading path, mean stress decreases during deformation. Under fully drained conditions where pore pressure remains constant, the effective stress decreases in these experiments, analoguous to increasing pore pressure. Our preliminary results indicate that: 1) frictional strength is comparable to that observed under conventional loading; 2) the rate of fracture energy release is considerably slower, which bears similar characteristics with observed slow slip events. Microstructural analyses on the deformed samples provide experimental constraints on deformation mechanisms associated with slow slip events.

  19. Dynamic Action Units Slip in Speech Production Errors

    ERIC Educational Resources Information Center

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

    2007-01-01

    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…

  20. Flash weakening of serpentinite at near-seismic slip rates

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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 μm 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.

  1. 6. VIEW OF BARGE SLIP (CALLED MASON'S CANAL, WHICH EXTENDS ...

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

    6. VIEW OF BARGE SLIP (CALLED MASON'S CANAL, WHICH EXTENDS OFF THE SOUTH BRANCH OF THE CHICAGO RIVER) AND COAL DOCK; TO THE RIGHT IS THE EAST FACADE OF THE 1959 GENERATING STATION. LOOKING SOUTHWEST. - Commonwealth Electric Company, Fisk Street Electrical Generating Station, 1111 West Cermak Avenue, Chicago, Cook County, IL

  2. Chaotic mixing in a planar, curved channel using periodic slip

    SciTech Connect

    Garg, P.; Picardo, J. R.; Pushpavanam, S.

    2015-03-15

    We propose a novel strategy for designing chaotic micromixers using curved channels confined between two flat planes. The location of the separatrix between the Dean vortices, induced by centrifugal forces, is dependent on the location of the maxima of axial velocity. An asymmetry in the axial velocity profile can change the location of the separatrix. This is achieved physically by introducing slip alternatingly at the top and bottom walls. This leads to streamline crossing and Lagrangian chaos. An approximate analytical solution of the velocity field is obtained using perturbation theory. This is used to find the Lagrangian trajectories of fluid particles. Poincare sections taken at periodic locations in the axial direction are used to study the extent of chaos. We study two microchannel designs, called circlet and serpentine, in which the Dean vortices in adjacent half cells are co-rotating and counter-rotating, respectively. The extent of mixing, at low Re and low slip length, is shown to be greater in the serpentine case. Wide channels are observed to have much better mixing than tall channels; an important observation not made for separatrix flows till now. Eulerian indicators are used to gauge the extent of mixing, with varying slip length, and it is shown that an optimum slip length exists which maximizes the mixing in a particular geometry. Once the parameter space of relatively high mixing is identified, detailed variance computations are carried out to identify the detailed features.

  3. Fluid slip ring transfers coolant to rotating equipment

    NASA Technical Reports Server (NTRS)

    Mains, D. K.

    1971-01-01

    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.

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

    PubMed

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

    2014-01-01

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

  5. Pipeline joint protector

    SciTech Connect

    Baker, R.

    1989-02-28

    This patent describes a weight coated pipeline joint protective apparatus for protecting pipeline joints against impact or high stress concentrations. It consists of a high density plastic sheet wrapped around a pipeline joint with the opposite edges of such sheet overlaying the weight of coat material on the abutting pipes forming the joint. The first end of the sheet overlaps the wrapped sheet with means for securing such first end to the sheet surface near or adjacent to the opposite end of such sheet.

  6. Compositional, mechanical and hydrologic controls on fault slip behavior

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.

    In order to examine the roles of a variety of factors that are likely important in regulating the occurrence or lack of seismic slip, I evaluate the results of numerous laboratory studies of fault behavior, focusing on the effects of fault mineralogy, mechanical effects, and interactions between fluids and faulting processes. More specifically, these experiments are designed to investigate the underlying mechanisms controlling the transition from aseismic slip at shallow levels in the crust to seismic slip at depth, known as the updip limit of the seismogenic zone. Results of laboratory experiments indicate that mineralogy of fault gouge is a major control on fault behavior. The clay mineral montmorillonite (smectite) has been noted for its potential effect on seismogenesis in subduction zones (as well as all faults in general) due to its ability to take up water in its crystal structure. Dehydration of montmorillonite tends to increase its frictional strength as well as increase its propensity for seismic slip, as documented by a decrease in the frictional velocity dependence parameter a-b. However, the observed decrease in a-b is assisted by both increasing relative quartz percentage and increasing normal stress, implying that the onset of seismic behavior with increasing depth should not be attributed solely to smectite dehydration. Furthermore, clay-rich gouges in general, including those consisting of montmorillonite, illite, and chlorite, are both frictionally weak (mu < 0.35) and velocity-strengthening (frictionally stable, a-b > 0) at fluid-saturated conditions and effective normal stresses up to ˜60 MPa. Sheared gouges may also exhibit low fault-perpendicular permeability (k < 1x10-18), making them candidates to host high pore pressure. This indicates that faults containing granular, clay-rich gouges are unlikely to show seismic behavior, due their velocity-strengthening nature and stabilizing hydro-mechanical effects resulting from low permeability. In

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

    NASA Technical Reports Server (NTRS)

    Wright, C. Wayne

    2009-01-01

    A system that includes a Global Positioning System (GPS) antenna and associated apparatus for keeping the antenna aimed upward has been developed for use aboard a remote-sensing-survey airplane. The purpose served by the system is to enable minimum- cycle-slip reception of GPS signals used in precise computation of the trajectory of the airplane, without having to restrict the airplane to maneuvers that increase the flight time needed to perform a survey. Cycle slip signifies loss of continuous track of the phase of a signal. Minimum-cycle-slip reception is desirable because maintaining constant track of the phase of the carrier signal from each available GPS satellite is necessary for surveying to centimeter or subcentimeter precision. Even a loss of signal for as short a time as a nanosecond can cause cycle slip. Cycle slips degrade the quality and precision of survey data acquired during a flight. The two principal causes of cycle slip are weakness of signals and multipath propagation. Heretofore, it has been standard practice to mount a GPS antenna rigidly on top of an airplane, and the radiation pattern of the antenna is typically hemispherical, so that all GPS satellites above the horizon are viewed by the antenna during level flight. When the airplane must be banked for a turn or other maneuver, the reception hemisphere becomes correspondingly tilted; hence, the antenna no longer views satellites that may still be above the Earth horizon but are now below the equatorial plane of the tilted reception hemisphere. Moreover, part of the reception hemisphere (typically, on the inside of a turn) becomes pointed toward ground, with a consequent increase in received noise and, therefore, degradation of GPS measurements. To minimize the likelihood of loss of signal and cycle slip, bank angles of remote-sensing survey airplanes have generally been limited to 10 or less, resulting in skidding or slipping uncoordinated turns. An airplane must be banked in order to make

  8. The 3-D surface deformation, coseismic fault slip and after-slip of the 2010 Mw6.9 Yushu earthquake, Tibet, China

    NASA Astrophysics Data System (ADS)

    Zhang, Guohong; Shan, Xinjian; Feng, Guangcai

    2016-07-01

    Using SAR interferometry on C band Envisat descending track and L band ALOS ascending track SAR images, respectively, we firstly obtain two coseismic deformation fields and one postseismic deformation of the 2010 Yushu earthquake, Tibet, China. In the meanwhile, we also obtain the azimuthal coseismic deformation of the Yushu event by Multi Aperture Interferometry (MAI) technique. With the 3 components of one-dimensional coseismic InSAR measurements, we resolve the complete 3-dimensional deformation of the 2010 Yushu event, which shows conformity and complexity to left lateral slip mechanism. The horizontal deformation is basically consistent with a sinistral slip event; whereas the vertical displacement does show certain level of complexity, which we argue is indicative of local fault geometry variation. Based on the InSAR data and elastic dislocation assumption, we invert for coseismic fault slip and early after-slip of the Yushu event. Our inversion results show major coseismic left lateral strike slip with only minor thrust component. The after-slip model fills most of the slip gaps left by the coseismic fault slip and finds a complementary slip distribution to the coseismic fault slip, which is a good indicator that future earthquake potential on the Yushu segment has been significantly reduced.

  9. Dynamic Mechanochemistry of Seismic Slip -Nano Spherules Lubrication

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  10. Dehydration-induced porosity waves and episodic tremor and slip

    NASA Astrophysics Data System (ADS)

    Skarbek, Rob M.; Rempel, Alan W.

    2016-02-01

    Episodic tremor and slip (ETS) along the subduction interface takes place where there is abundant evidence for elevated, near-lithostatic pore pressures, at sufficiently great depths (30-45 km) that chemical dehydration reactions must act as their dominant source. We simulate fluid and heat flow while tracking the location of a vertically oriented, one-dimensional column of material as it subducts through the slow slip and tremor zone. The material in the column is transformed through a pressure-dependent and temperature-dependent dehydration reaction that we describe with a generalized nonlinear kinetic rate law. Column deformation is largely dominated by viscous creep, with a closure rate that depends linearly on porosity. This behavior causes the dehydration reaction to generate traveling porosity waves that transport increased fluid pressures within the slow slip region. To explore the possibility that the observed periodicity of slow slip and tremor in subduction zones can be explained by the migration of such porosity waves, we derive a dispersion relation that accurately describes our numerical results. We also obtain an expression for how the thickness of the dehydrating layer is expected to vary as a function of the parameters in the reaction rate law. Although the amplitudes of pore pressure perturbations rival those that are produced by known external forcings (e.g., tides or passing surface waves), our analysis suggests that given reasonable estimates of rock viscosity, permeabilities in the range 6.5×10-15 to 5×10-10 m2 are required for porosity wave trains to form at periods comparable to those of slow slip and tremor.

  11. Dynamic Strength of Peridotite at Seismic Slip Rates: Experimental Results

    NASA Astrophysics Data System (ADS)

    Del Gaudio, P.; di Toro, G.; Han, R.; Hirose, T.; Shimamoto, T.; Cocco, M.

    2006-12-01

    Ultramafic pseudotachylytes (solidified melts produced during seismic slip) decorate exhumed faults within the Balmuccia peridotite from the Ivrea zone (Italy). Unpublished studies suggest that these pseudotachylytes were produced in the upper-mantle/lower-crust. Kanamori et al. (1998) proposed extensive production of seismic melts during the Mw = 8.3 Bolivian 1994 deep focus (~600 km in depth) earthquake. It follows that seismic melting might occur in the mantle. We conducted high-velocity rock friction experiments with the Balmuccia peridotite to determine the dynamic strength of faults in the presence of ultramafic melts. During each experiment, shear stress evolved with displacement: after an initial peak shear stress, fault strength gradually decreased towards a steady-state value. Dynamic fault weakening was associated with the formation of a molten layer along the slipping zone. By performing experiments for increasing normal stresses (5 to 13 MPa) and slip rates (0.37÷1.14 m/s or ~seismic slip rates), steady-state shear stress (1) slightly increased with increasing normal stress and (2), for a given normal stress, decreased with increasing slip rate. The ratio between steady-state shear stress and normal stress was 0.13, well below the solid rock friction coefficient (~0.8). Experiments conducted under argon or fresh air flux yielded similar shear stress magnitudes, suggesting that olivine oxidation did not affect significantly the fault strength in the high-velocity experiments. The slight dependence of shear stress with normal stress suggests melt lubrication. Since the physics of melt lubrication is somehow predictable (see poster by Nielsen et al.), these experimental results might be extrapolated to the study of rupture dynamics in mantle rocks.

  12. Fusion by earthquake fault friction: Stick or slip?

    NASA Astrophysics Data System (ADS)

    Fialko, Yuri; Khazan, Yakov

    2005-12-01

    Field observations of pseudotachylites and experimental studies of high-speed friction indicate that melting on a slipping interface may significantly affect the magnitude of shear stresses resisting slip. We investigate the effects of rock melting on the dynamic friction using theoretical models of shear heating that couple heat transfer, thermodynamics of phase transitions, and fluid mechanics. Results of laboratory experiments conducted at high (order of m/s) slip velocities but low (order of MPa) normal stresses suggest that the onset of frictional melting may give rise to substantial increases in the effective fault strength, presumably due to viscous effects. However, extrapolation of the modeling results to in situ conditions suggests that the efficiency of viscous braking is significantly reduced under high normal and shear stresses. When transient increases in the dynamic fault strength due to fusion are not sufficient to inhibit slip, decreases in the effective melt viscosity due to shear heating and melting of clasts drastically decrease the dynamic friction, resulting in a nearly complete stress drop ("thermal runaway"). The amount of energy dissipation associated with the formation of pseudotachylites is governed by the temperature dependence of melt viscosity and the average clast size in the fault gouge prior to melting. Clasts from a coarse-grained gouge have lower chances of survival in a pseudotachylite due to a higher likelihood of nonequilibrium overheating. The maximum temperature and energy dissipation attainable on the fault surface are ultimately limited by either the rock solidus (via viscous braking, and slip arrest) or liquidus (via thermal runaway and vanishing resistance to sliding). Our modeling results indicate that the thermally activated fault strengthening and rupture arrest are unlikely to occur in most mafic protoliths but might be relevant for quartz-rich rocks, especially at shallow (<5-7 km) depths where the driving shear

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

    USGS Publications Warehouse

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

    1998-01-01

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

  14. Distribution of Slip at the Northern Sumatran Fault System

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = τ / σn (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (σ1-σn) / (σ1-σ3) (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

  16. Nonvolcanic Tremors and Intraslab Fluid Migration in Guerrero, Mexico, During Slow Slip Transients

    NASA Astrophysics Data System (ADS)

    Cruz-Atienza, V. M.; Husker, A. L.; Villafuerte, C. D.; Caballero, E.; Legrand, D.; Kostoglodov, V.

    2014-12-01

    Observations in different subduction zones have suggested that overpressured fluids close to the plate interface may be related to the origin of nonvolcanic tremors (NVT) and low frequency earthquakes (LFE). One condition for a causal relationship to exist between fluids and such seismicity is their spatial collocation. Fluids at nearly lithostatic pressures within the top few kilometers of the oceanic crust have been inferred in several subduction zones, including the province of Guerrero, Mexico. However, NVT hypocentral depths in this region have been poorly resolved so that casualty could not even be tested as a hypothesis. In this work, we report NVT relocations from a 3-year-catalog in Guerrero that includes the period of the Slow Slip Earthquake (SSE) of 2006. We used a new location technique called the "Tremor Energy and Polarization" (TREP) method (Cruz-Atienza et al., JGR, 2014), which jointly determines the source location and focal mechanism of sustained tremor signals by simultaneously inverting (1) the energy spatial distribution, (2) the energy spatial derivatives, and (3) the azimuthal direction of the particle motion polarization ellipsoid. In agreement with previous works, NVT epicentral locations concentrate between 200 and 230 km from the trench and then migrate ~40 km trenchward during the occurrence of the SSE. However, unlike earlier investigations, most NVT hypocenters lie at 43 km depth near the plate interface and have subparallel rake angles to the Cocos plate convergence direction. These results are consistent with independent locations and mechanisms of LFE in the region and allow us to examine the casualty hypothesis mentioned above. Poroelastic modeling of fluid transport during two SSEs in Guerrero (Villafuerte and Cruz-Atienza, AGU, 2014) show that fluids migrate towards the spots where this seismicity occurs with maximum velocities between 10-3 and 10-9 km/day, which are more than 3 orders of magnitude smaller than the LFE

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  18. Paleomagnetic and structural evidence for oblique slip in a fault-related fold, Grayback monocline, Colorado

    USGS Publications Warehouse

    Tetreault, J.; Jones, C.H.; Erslev, E.; Larson, S.; Hudson, M.; Holdaway, S.

    2008-01-01

    Significant fold-axis-parallel slip is accommodated in the folded strata of the Grayback monocline, northeastern Front Range, Colorado, without visible large strike-slip displacement on the fold surface. In many cases, oblique-slip deformation is partitioned; fold-axis-normal slip is accommodated within folds, and fold-axis-parallel slip is resolved onto adjacent strike-slip faults. Unlike partitioning strike-parallel slip onto adjacent strike-slip faults, fold-axis-parallel slip has deformed the forelimb of the Grayback monocline. Mean compressive paleostress orientations in the forelimb are deflected 15??-37?? clockwise from the regional paleostress orientation of the northeastern Front Range. Paleomagnetic directions from the Permian Ingleside Formation in the forelimb are rotated 16??-42?? clockwise about a bedding-normal axis relative to the North American Permian reference direction. The paleostress and paleomagnetic rotations increase with the bedding dip angle and decrease along strike toward the fold tip. These measurements allow for 50-120 m of fold-axis-parallel slip within the forelimb, depending on the kinematics of strike-slip shear. This resolved horizontal slip is nearly equal in magnitude to the ???180 m vertical throw across the fold. For 200 m of oblique-slip displacement (120 m of strike slip and 180 m of reverse slip), the true shortening direction across the fold is N90??E, indistinguishable from the regionally inferred direction of N90??E and quite different from the S53??E fold-normal direction. Recognition of this deformational style means that significant amounts of strike slip can be accommodated within folds without axis-parallel surficial faulting. ?? 2008 Geological Society of America.

  19. Compound solder joints

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  20. Wedge Joints for Trusses

    NASA Technical Reports Server (NTRS)

    Wood, Kenneth E.

    1987-01-01

    Structure assembled rapidly with simple hand tools. Proposed locking wedge joints enable rapid assembly of lightweight beams, towers, scaffolds, and other truss-type structures. Lightweight structure assembled from tubular struts joined at nodes by wedge pins fitting into mating slots. Joint assembled rapidly by seating wedge pin in V-shaped slots and deforming end of strut until primary pawl engages it.

  1. "Nonfloating" universal joint

    NASA Technical Reports Server (NTRS)

    Appleberry, W. T.

    1978-01-01

    Modified crowned-spline joint is lightweight, durable, and requires minimum of parts. It does not use rubber cushions to limit play and is useful over wide temperature range. It has inner ball and socket to provide rigid connection with no axial play. Joint can be adapted to form pinned connection between segmented torque tubes.

  2. Sacroiliac joint pain - aftercare

    MedlinePlus

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

  3. Acoustic properties of the full spectrum of stick-slip events from stable sliding to dynamic rupture: insights on the mechanics of slow earthquakes and transient fault slip.

    NASA Astrophysics Data System (ADS)

    Scuderi, M. M.; Marone, C.; Tinti, E.; Di Stefano, G.; Collettini, C.

    2015-12-01

    Seismic and geodetic observations show that fault slip occurs via a spectrum of behaviors that include slow earthquakes and tectonic tremor. These phenomena have been observed in a variety of tectonic environments worldwide, however the underlying processes are poorly understood. Here we report on lab experiments on simulated fault gouge. We used the double direct shear configuration and varied the loading system stiffness (k) to produce the full spectrum of stick-slip behaviors, with durations ranging from 10-3 to 1 second. We measured frictional rheology and elastic wave properties throughout the stick-slip cycle for slow and fast events. When the loading stiffness is greater than the fault zone critical rheologic stiffness (kc) we observe stable frictional sliding. For k≈kc we document emergent slow-slip events from steady shear. When kc>k we observe audible stick-slip. Stick slip stress drop and event duration vary systematically as a function of the ratio k/kc. For slow-slip events, p-wave velocity (Vp) begins to decrease prior to the stress drop and the maximum slip velocity during failure coincides with the largest drop in Vp. Dynamic stick-slip events do not show precursory changes in Vp prior to failure. We find that fault creep and precursory changes in wave properties vary systematically with stick-slip event duration, with slower events showing larger precursory changes. In general, Vp begins to decrease prior to failure and drops abruptly as slip velocity accelerates to a peak value. The drop in Vp appears to be larger during dynamic stick-slip than for slow-slip events. Our results suggest that slow earthquakes and transient fault slip are governed by the same frictional processes as dynamic stick-slip and represent a continuum in the spectrum of fault slip. We show that fault gouge elastic properties evolve during the pre-seismic stage of slow-slip, which could provide an important means of assessing short term seismic hazard.

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

    USGS Publications Warehouse

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

    2005-01-01

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

  5. Jelly Quakes - Characteristics of periodic slip events in an analog model of strike slip seismotectonics using ballistic gelatin.

    NASA Astrophysics Data System (ADS)

    Rudolf, Michael; Rosenau, Matthias; Oncken, Onno

    2016-04-01

    Large lithospheric strike-slip faults, such as the San-Andreas Fault, North-Anatolian Fault, or the Tancheng-Lujiang Faultzone, are major sources of seismic hazard. The interplay of complex 3D-geometry and displacement style along the fault, coupled with a varying rheological layering makes it very difficult to model these faults on all relevant timescales. Here we present a novel experimental approach to model intra- and interplate strike-slip faults using a physical/ analog model. We model earthquakes as a stick-slip process, following a rate-and-state frictional law, with glass beads as granular material within a molded fault zone. Crustal elasticity is introduced by using ballistic gelatin (30 w%, pig skin) as analog material. Furthermore, the low-strength and viscous deep crust below 15 km depth, is modeled using a viscoelastic silicone oil (PDMS-G30M). The layered model crust floats on sugar syrup and is compressed in pure shear vice configuration. We monitor the compressive force along with surface kinematics from optical image correlation. The fault is oriented at 45° to the compression direction imposing ideal strike-slip kinematics onto it. After an initial loading phase the model shows periodic slip events occurring alongside with creep on the fault. Using digital image correlation, surface displacement maps are obtained which are similar to those of natural earthquakes. Coseismic displacement along strike is showing a similar bell-shaped distribution as for natural faults. Furthermore, the recurrence intervals and stress drops are scalable to the natural prototype. The modeling results are combined with numerical rate-and-state models using physical parameters from the experiment. This enables us to explore a wide range of parameters and to draw connections between the parameters that control the behavior of seismic and aseismic fault systems.

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

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Jin

    2009-11-01

    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 μm-thick air layer, for example, the slip length is calculated to be roughly 50 or 500 μm, 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 μm. 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.

  7. A possible restart of an interplate slow slip adjacent to the Tokai seismic gap in Japan

    NASA Astrophysics Data System (ADS)

    Ozawa, Shinzaburo; Tobita, Mikio; Yarai, Hiroshi

    2016-04-01

    The Tokai region of Japan is known to be a seismic gap area and is expected to be the source region of the anticipated Tokai earthquake with a moment magnitude of over 8. Interplate slow slip occurred from approximately 2001 and subsided in 2005 in the area adjacent to the source region of the expected Tokai earthquake. Eight years later, the Tokai region again revealed signs of a slow slip from early 2013. This is the first evidence based on a dense Global Positioning System network that Tokai long-term slow slips repeatedly occur. Two datasets with different detrending produce similar transient crustal deformation and aseismic slip models, supporting the occurrence of the Tokai slow slip. The center of the current Tokai slow slip is near Lake Hamana, south of the center of the previous Tokai slow slip. The estimated moments, which increase at a roughly constant rate, amount to that of an earthquake with a moment magnitude of 6.6. If the ongoing Tokai slow slip subsides soon, it will suggest that there are at least two different types of slow slip events in the Tokai long-term slow slip area: that is, a large slow slip with a moment magnitude of over 7 with undulating time evolution and a small one with a moment magnitude of around 6.6 with a roughly linear time evolution. Because the Tokai slow slip changes the stress state to one more favorable for the expected Tokai earthquake, intense monitoring is going on.

  8. Required coefficient of friction during level walking is predictive of slipping.

    PubMed

    Beschorner, Kurt E; Albert, Devon L; Redfern, Mark S

    2016-07-01

    The required coefficient of friction (RCOF) is frequently reported in the literature as an indicator of slip propensity. This study aimed to further develop slip prediction models based on RCOF by examining slips under moderately slippery conditions where the RCOF was approximately equal to the available coefficient of friction. Baseline RCOFs were found for normal walking trials and then an unexpected slip was introduced with a moderately slippery boot-floor contaminant combination for thirty-one subjects. Slip outcomes (i.e., whether a subject experienced a slip) were assessed based on the displacement of a marker placed on the heel. A logistic regression analysis was used to model the impact of RCOF on slipping. Results showed that subjects who walked with a greater RCOF were found to have a higher probability of slipping. The predicted probability of a slip across the RCOF ranged from 3% to 95% and an increase of 0.01 in RCOF was associated with a slipping odds ratio of 1.7. Thus, modest differences in RCOF can have a dramatic impact on slip propensity. This study shows that RCOF can be a sensitive and valid predictor of slipping in realistic frictional environments. PMID:27367937

  9. An Experimental Investigation into the Perception of the Slips of the Tongue.

    ERIC Educational Resources Information Center

    Tent, J. Clark, J. E.

    1980-01-01

    Describes an experiment designed to verify the notion that many slips of the tongue go undetected and demonstrates that phonemic slips of the tongue are perceived less often than nonphonemic slips of the tongue. Findings also indicate that the latter disturb perception of segments in the rest of the sentence more than the former. (Author/MES)

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

    USGS Publications Warehouse

    Peng, Zhigang; Gomberg, Joan

    2010-01-01

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

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

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = τ / σn (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (σ1-σn) / (σ1-σ3) (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

  12. Slow slip events and seismic tremor at circum-Pacific subduction zones

    NASA Astrophysics Data System (ADS)

    Schwartz, Susan Y.; Rokosky, Juliana M.

    2007-09-01

    It has been known for a long time that slip accompanying earthquakes accounts for only a fraction of plate tectonic displacements. However, only recently has a fuller spectrum of strain release processes, including normal, slow, and silent earthquakes (or slow slip events) and continuous and episodic slip, been observed and generated by numerical simulations of the earthquake cycle. Despite a profusion of observations and modeling studies the physical mechanism of slow slip events remains elusive. The concurrence of seismic tremor with slow slip episodes in Cascadia and southwestern Japan provides insight into the process of slow slip. A perceived similarity between subduction zone and volcanic tremor has led to suggestions that slow slip involves fluid migration on or near the plate interface. Alternatively, evidence is accumulating to support the notion that tremor results from shear failure during slow slip. Global observations of the location, spatial extent, magnitude, duration, slip rate, and periodicity of these aseismic slip transients indicate significant variation that may be exploited to better understand their generation. Most slow slip events occur just downdip of the seismogenic zone, consistent with rate- and state-dependent frictional modeling that requires unstable to stable transitional properties for slow slip generation. At a few convergent margins the occurrence of slow slip events within the seismogenic zone makes it highly likely that transitions in frictional properties exist there and are the loci of slow slip nucleation. Slow slip events perturb the surrounding stress field and may either increase or relieve stress on a fault, bringing it closer to or farther from earthquake failure, respectively. This paper presents a review of slow slip events and related seismic tremor observed at plate boundaries worldwide, with a focus on circum-Pacific subduction zones. Trends in global observations of slow slip events suggest that (1) slow slip is a

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

    NASA Astrophysics Data System (ADS)

    Maury, Julie; Aochi, Hideo; Radiguet, Mathilde

    2014-05-01

    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

  14. Dual megathrust slip behaviors of the 2014 Iquique earthquake sequence

    NASA Astrophysics Data System (ADS)

    Meng, Lingsen; Huang, Hui; Bürgmann, Roland; Ampuero, Jean Paul; Strader, Anne

    2015-02-01

    The transition between seismic rupture and aseismic creep is of central interest to better understand the mechanics of subduction processes. A Mw 8.2 earthquake occurred on April 1st, 2014 in the Iquique seismic gap of northern Chile. This event was preceded by a long foreshock sequence including a 2-week-long migration of seismicity initiated by a Mw 6.7 earthquake. Repeating earthquakes were found among the foreshock sequence that migrated towards the mainshock hypocenter, suggesting a large-scale slow-slip event on the megathrust preceding the mainshock. The variations of the recurrence times of the repeating earthquakes highlight the diverse seismic and aseismic slip behaviors on different megathrust segments. The repeaters that were active only before the mainshock recurred more often and were distributed in areas of substantial coseismic slip, while repeaters that occurred both before and after the mainshock were in the area complementary to the mainshock rupture. The spatiotemporal distribution of the repeating earthquakes illustrates the essential role of propagating aseismic slip leading up to the mainshock and illuminates the distribution of postseismic afterslip. Various finite fault models indicate that the largest coseismic slip generally occurred down-dip from the foreshock activity and the mainshock hypocenter. Source imaging by teleseismic back-projection indicates an initial down-dip propagation stage followed by a rupture-expansion stage. In the first stage, the finite fault models show an emergent onset of moment rate at low frequency (< 0.1 Hz), while back-projection shows a steady increase of high frequency power (> 0.5 Hz). This indicates frequency-dependent manifestations of seismic radiation in the low-stress foreshock region. In the second stage, the rupture expands in rich bursts along the rim of a semi-elliptical region with episodes of re-ruptures, suggesting delayed failure of asperities. The high-frequency rupture remains within an

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. On the Rheology of Slow Slip Events Around Continental Moho

    NASA Astrophysics Data System (ADS)

    Gao, X.; Wang, K.; Wada, I.; He, J.

    2015-12-01

    Slow slip events (SSEs) occur in various tectonic settings but are the most abundant around the depth of upper-plate Moho in warm-slab subduction zones such as Cascadia and Nankai, accompanied with non-valcanic tremor. The paucity or absence of these near-Moho SSEs in many other subduction zones and the relationship of these SSEs with the megathrust seismogenic zone are intriguing questions of fundamental importance. We address these questions by examining Frictional-Viscous Transitions (FVTs) along subduction faults. Our key hypothesis is that there is a sharp decrease in the frictional stength of subduction faults across its intersection with the continental Moho for two reasons: (1) Enrichment of weak hydrous minerals such as talc due to the hydration of the base of the mantle wedge, and (2) elevated pore fluid pressure in the fault zone because of serpentine (antigorite) saturation of the mantle wedge corner which retards further fluid consumption and decreases permeability. Through thermal modelling using heat flow data as constraints, we found that for Cascadia, Nankai, and Hikurangi, there are two FVTs, with the first one being shallower than the Moho. At the Moho, the fault returns to the friction mode, but with slip behaviour affected by the presence of hydrous minerals and high fluid pressure. We propose this is where near-Moho SSEs occur. Farther downdip, the second FVT occurs and serves to limit the depth extent of the SSEs. Coseismic slip is limited to be shallower than the first FVT, such that frictional slip around the Moho occurs interseismically as SSEs. This mechanism also explains the occurrence of tremor, believed to represent very small SSEs, along the San Andreas fault around the Moho depth. In a way, this mechanism is akin to the "jelly-sandwich" rheology model of the continental lithosphere, but the onset of the lower slice of bread is due to a decrease in frictional strength as opposed to an increase in viscous strength. For the other

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  18. Microstructural evolution from stable sliding to fast stick slip: insights from rock deformation experiments on quartz

    NASA Astrophysics Data System (ADS)

    Collettini, Cristiano; Scuderi, Marco M.; Viti, Cecilia; Marone, Chris

    2016-04-01

    Inferring microstructural evolution and associated fault slip behaviour along natural and/or experimental faults is a long-standing problem in fault mechanics. For example, does grain-size reduction and shear localization facilitate earthquake slip or vice versa? We have sheared granular layers of quartz gouge in a double direct shear configuration using a biaxial apparatus. We varied loading stiffness and applied normal stresses to produce a spectrum of slip modes from stable sliding at 10 μm/s, slow stick-slip (average slip velocity 100 μm/s) and fast stick slip (average slip velocity 4 mm/s). At the end of the experiments we collected the experimental fault rocks for microstructural investigations. Additional samples were collected from control experiments to investigate shear fabric development and microstructural features before the onset of stick-slip instabilities. We investigated the role of normal stress and stick-slip properties, including slip velocity, in determining fault zone microstructural features. Ranging from stable sliding to fast stick-slip we observe a progressive localization of deformation along fault parallel boundary shear planes. Only during fast stick-slip is the deformation localized along continuous, thin (1-2 microns wide), boundary parallel shear planes. The shear zones are composed of nanograins dispersed within a patchy matrix. We conducted TEM analyses to characterize these materials. In experiments at the same normal stress, fast stick-slip results in localized shear zones and fabric with nanograins whereas for stable sliding the microstructure does not show a significant grain size reduction and localization. Our results indicate that the fault rheological properties and fault slip behaviour, ranging from stable to unstable slip, plays a significant role in shear localization and fault zone fabric development.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Silicification Strengthening and Non-Localization of Slip in Dilational Sites Along Strike-Slip Faults, Mt Isa Inlier, Australia

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.; Ghisetti, F. C.; Begbie, M. J.

    2006-12-01

    Sets of late- or post-orogenic brittle strike-slip faults disrupt the complex of subgreenschist to amphibolite facies metasediments and metavolcanics intruded by granites that make up the Proterozoic Mt Isa inlier of NW Queensland, Australia. Subvertical dextral faults with offsets <25 km generally strike NE-SW to NNE- SSW and mutually cross-cut a conjugate set of sinistral faults striking NW-SE to NNW-SSE. Together, they define a regional stress field with horizontal maximum compression, σ1, at an azimuth of ~100° and horizontal σ3 trending ~010°. The strike-slip faults are recessive except in dilational sites where upwelling hydrothermal fluids have led to silicification of the cataclastic shear zones which then form prominent blade-like ridges sometimes extending for kilometres across the semi-arid terrain. Silicification textures suggest the faults have been exhumed from epizonal boiling environments (<1-2 km depth). The mineralized fault segments include sinuous releasing bends where the fault trace is deflected <10° as well as more abrupt dilational stepovers linking en echelon fault segments. Particularly noticeable is the change from recessive to upstanding wall-like character of the faults as they approach dilational stepovers linking en echelon fault segments. Where recessive, limited outcrop is consistent with standard models of brittle infrastructure with a fault core localized in a damage zone tens of metres in width. By contrast, along the dilational segments the faults are defined by one or more subvertical cataclastic shear zones (CSZ), commonly ranging up to 10 m or so in thickness, made up of silicified microbreccia-cataclasite containing a mixture of protolith and hydrothermal vein fragments. The composite fabric of the CSZ includes: (1) local grain-size banding developed subparallel to margins; (2) irregular quartz-cemented breccias of varying dilation; (3) innumerable subvertical, cm - dm quartz-veins of variable planarity lying

  1. MISR JOINT_AS Data

    Atmospheric Science Data Center

    2014-07-21

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

  2. Pressure vessel flex joint

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor)

    1992-01-01

    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.

  3. Simultaneous dislocation of radiocapitellar and distal radioulnar joint.

    PubMed

    Nishi, Tomio; Suzuki, Noriyuki; Tani, Takayuki; Aonuma, Hiroshi

    2013-01-01

    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. PMID:24194995

  4. Magmatically triggered slow slip at Kilauea Volcano, Hawaii.

    PubMed

    Brooks, Benjamin A; Foster, James; Sandwell, David; Wolfe, Cecily J; Okubo, Paul; Poland, Michael; Myer, David

    2008-08-29

    We demonstrate that a recent dike intrusion probably triggered a slow fault-slip event (SSE) on Kilauea volcano's mobile south flank. Our analysis combined models of Advanced Land Observing Satellite interferometric dike-intrusion displacement maps with continuous Global Positioning System (GPS) displacement vectors to show that deformation nearly identical to four previous SSEs at Kilauea occurred at far-field sites shortly after the intrusion. We model stress changes because of both secular deformation and the intrusion and find that both would increase the Coulomb failure stress on possible SSE slip surfaces by roughly the same amount. These results, in concert with the observation that none of the previous SSEs at Kilauea was directly preceded by intrusions but rather occurred during times of normal background deformation, suggest that both extrinsic (intrusion-triggering) and intrinsic (secular fault creep) fault processes can lead to SSEs. PMID:18755967

  5. Soft matter dynamics: Accelerated fluid squeeze-out during slip

    NASA Astrophysics Data System (ADS)

    Hutt, W.; Persson, B. N. J.

    2016-03-01

    Using a Leonardo da Vinci experimental setup (constant driving force), we study the dependency of lubricated rubber friction on the time of stationary contact and on the sliding distance. We slide rectangular rubber blocks on smooth polymer surfaces lubricated by glycerol or by a grease. We observe a remarkable effect: during stationary contact the lubricant is only very slowly removed from the rubber-polymer interface, while during slip it is very rapidly removed resulting (for the grease lubricated surface) in complete stop of motion after a short time period, corresponding to a slip distance typically of order only a few times the length of the rubber block in the sliding direction. For an elastically stiff material, poly(methyl methacrylate), we observe the opposite effect: the sliding speed increases with time (acceleration), and the lubricant film thickness appears to increase. We propose an explanation for the observed effect based on transient elastohydrodynamics, which may be relevant also for other soft contacts.

  6. Fault Zone Drainage, Heating and Melting During Earthquake Slip

    NASA Astrophysics Data System (ADS)

    Rempel, A. W.; Rice, J. R.; Jacques, L. M.

    2003-12-01

    The expansion of pore water caused by frictional heating during large crustal events provides a powerful weakening mechanism (Sibson, 1973; Lachenbruch, 1980). It may explain the magnitude of seismically inferred fracture energy and aspects of its variation with increased slip (Abercrombie and Rice, 2003; Rice et al., 2003; Rice, this section, 2003). The weakening is mediated by the effects of fluid transport, which are sensitive to the permeability structure of the fault zone and its modification by damage induced by the passing rupture front (Poliakov et al., 2002), as well as by the increase in pore pressure itself. Higher permeabilities allow partial drainage to occur, so that enough strength remains for the heat generated to cause partial melting of the fault gouge at large enough slip. We use recent field and laboratory data for fluid transport through pressurized fault gouge (e.g. Lockner et al., 2000; Wibberley and Shimamoto, 2003) to motivate models for drainage and melting during earthquake slip. A dramatic illustration of the role of drainage is provided by an idealized model in which we assume that a freshly damaged, highly permeable region extends right up to a localized shear zone of thickness ho=5 mm, with fixed porosity n and much lower permeability k. At 7 km depth, for n=0.02 and k=10-19 m2, the slip distance required to reach the onset of melting at 750oC is approximately 0.4 m for a constant friction coefficient of f=0.6. At 14 km depth, for n=0.01 and k=10-20 m2, the same temperature is reached after only 0.1 m of slip. Yet more efficient drainage might occur due to the permeability increases that accompany reductions in the effective stress, so that even more rapid temperature increases would be predicted. For example, with ten times higher k, melting begins after 0.1 m slip at 7 km depth and just 0.05 m at 14 km. At onset of melting the high melt viscosity impedes further drainage and, with increasing melt fraction, inter-particle contact is

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

    PubMed

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

    2014-11-01

    In an effort to design novel magnesium (Mg) alloys with high ductility, we present a first principles data based on the Density Functional Theory (DFT). The DFT was employed to calculate the generalized stacking fault energy curves, which can be used in the generalized Peierls-Nabarro (PN) model to study the energetics of basal slip and prismatic slip in Mg with and without solutes to calculate continuum scale dislocation core widths, stacking fault widths and Peierls stresses. The generalized stacking fault energy curves for pure Mg agreed well with other DFT calculations. Solute effects on these curves were calculated for nine alloying elements, namely Al, Ca, Ce, Gd, Li, Si, Sn, Zn and Zr, which allowed the strength and ductility to be qualitatively estimated based on the basal dislocation properties. Based on our multiscale methodology, a suggestion has been made to improve Mg formability. PMID:25273695

  8. Slip effect for thin liquid film on a rotating disk

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Masahiro

    1987-02-01

    A flow for thin liquid films on rotating disks has been theoretically and experimentally studied. Liquid depletion behavior during a spin-coating process is calculated by solving the Navier-Stokes equation, taking into account interface slip between liquid and disk. Excellent agreement is seen between the model prediction and experimental data. According to observed depletion behavior on thin liquid films for various spin-coating parameters, half life falls off at the inverse square of rotational speed, and increases when viscosity increases, although the increasing rate falls off. The interface slip, represented as an external friction coefficient, is thermodynamically explained by the different (Δrc) in critical surface tension (rc) values between the liquid and the disk, which will be proportional to the solubility parameter. An infinite external friction coefficient, representing nonslip flow, may be given, when Δrc is zero. Spin-off experiments for liquids of various rc values, prepared by differing surface treatments, support this consideration.

  9. A Novel Algorithm for Cycle Slip Detection and Repair

    NASA Astrophysics Data System (ADS)

    Sezen, U.; Arikan, F.

    2012-04-01

    Accurate and reliable estimation of ionospheric parameters are very important for correct functioning of communication, navigation and positioning satellite systems. In recent years, dual-frequency GPS receivers are widely used for estimation of Total Electron Content (TEC), which is defined as the line integral of the electron density along a ray path. Since both electron density and TEC are functions of solar, geomagnetic, gravitational and seismic activity, any disturbance along the ray path can be detected using GPS receiver observables. It is observed that, with the development of recent sophisticated receivers, disruptions due to the receiver antenna, hardware or outside obstructions are minimized. Most of the observed sudden disturbances are signal phase lock losses due to ionosphere. These sudden phase shifts are named as cycle slips and if not corrected, they may lead to positioning errors or incorrect TEC estimates. There are many methods in the literature that deal with cycle slips and their repairs, yet these methods are not matured to detect all kinds of cycle slips. Most algorithms require double differencing, and/or complicated Kalman Filters, Wavelet transforms, Neural Network models, and integration of external INS systems. In this study, we propose a fast and efficient algorithm for identifying the cycle slips on individual observables, classifying them for future investigations and finally repairing them for more accurate and reliable TEC estimates. The algorithm traces the pseudorange and phase observables and computes the geometry free combinations of L4 and P4. The sudden disturbances on L1, L2, P1, C1 and P2 are classified and noted for further use. Most of the cases, the disruptions are on phase observables, yet for a few occasions, a sudden disturbance is also observed on pseudorange observables. The algorithm, then, checks the epoch section where P4 exists continually. When a disruption on L1 or L2 occurs, it becomes evident on L4. When P4

  10. A silent slip event on the deeper Cascadia subduction interface.

    PubMed

    Dragert, G; Wang, K; James, T S

    2001-05-25

    Continuous Global Positioning System sites in southwestern British Columbia, Canada, and northwestern Washington state, USA, have been moving landward as a result of the locked state of the Cascadia subduction fault offshore. In the summer of 1999, a cluster of seven sites briefly reversed their direction of motion. No seismicity was associated with this event. The sudden displacements are best explained by approximately 2 centimeters of aseismic slip over a 50-kilometer-by-300-kilometer area on the subduction interface downdip from the seismogenic zone, a rupture equivalent to an earthquake of moment magnitude 6.7. This provides evidence that slip of the hotter, plastic part of the subduction interface, and hence stress loading of the megathrust earthquake zone, can occur in discrete pulses. PMID:11313500

  11. Quantum Phase Slips in Topological Josephson Junction Rings

    NASA Astrophysics Data System (ADS)

    Rodriguez Mota, Rosa; Vishveshwara, Smitha; Pereg-Barnea, Tami

    We study quantum phase slip processes (QPS) in a ring of N topological superconducting islands joined by Josephson junctions and threaded by magnetic flux. In this array, neighboring islands interact through the usual charge 2e Josephson tunneling and the Majorana assisted charge e tunneling. When the charging energy associated with the island's capacitance is zero, the energy vs. flux relation of the system is characterized by parabolas centered around even or odd multiples of the superconducting flux quantum, depending on the parity of the system. For small but non-zero charging energy, quantum fluctuations can lead to tunneling between these classical states. In this work, we calculate the amplitude of these tunneling processes, commonly known as quantum phase slips. We also add gate voltages to our system and study how the amplitude of QPS in these topological Josephson array is modified by Aharanov-Casher interference effects.

  12. Case history of a slip-type rockburst

    NASA Astrophysics Data System (ADS)

    Williams, T. J.; Wideman, C. J.; Scott, D. F.

    1992-09-01

    First-motion analyses of digital seismic records and an assessment of damage provided conclusive evidence that a fault-slip source mechanism was responsible for a Richter magnitude 2 that occurred at the Lucky Friday Mine on April 13, 1990. This event was the first time that movement along an argillite bed had been observed after the macroseismic monitoring system had been installed. The physical evidence of a shear-slip type failure established confidence in using double-couple, first-motion analyses for the macroseismic system. The U.S. Bureau of Mines is conducting this research as part of its mission to enhance safety by reducing rockburst hazards in mines.

  13. Liquid water can slip on a hydrophilic surface

    PubMed Central

    Ho, Tuan Anh; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Striolo, Alberto

    2011-01-01

    Understanding and predicting the behavior of water, especially in contact with various surfaces, is a scientific challenge. Molecular-level understanding of hydrophobic effects and their macroscopic consequences, in particular, is critical to many applications. Macroscopically, a surface is classified as hydrophilic or hydrophobic depending on the contact angle formed by a water droplet. Because hydrophobic surfaces tend to cause water slip whereas hydrophilic ones do not, the former surfaces can yield self-cleaning garments and ice-repellent materials whereas the latter cannot. The results presented herein suggest that this dichotomy might be purely coincidental. Our simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip. Further analysis provides details on the molecular mechanism responsible for this surprising result. PMID:21911406

  14. Slip history of the 1995 Kobe, Japan, earthquake determined from strong motion, teleseismic, and geodetic data

    USGS Publications Warehouse

    Wald, D.J.

    1996-01-01

    Near-source ground motions, teleseismic body waveforms, and geodetic displacements produced by the 1995 Kobe, Japan, earthquake have been used to determine the spatial and temporal dislocation pattern on the faulting surfaces. Analysis of the slip model indicates that the ground motions recorded within the severely damaged region of Kobe originated from the region of relatively low slip (about 1 m) deep beneath Kobe and not from the shallow, higher slip regions (about 3 m) beneath Aqaji Island. Although the slip was relatively low beneath Kobe, the combined effects of source rupture directivity, a short slip duration, and site amplification conspired to generate very damaging ground motions within the city.

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

    USGS Publications Warehouse

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

    1996-01-01

    Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The

  16. First metatarsophalangeal joint arthrodesis.

    PubMed

    Rajczy, Robert M; McDonald, Patrick R; Shapiro, Howard S; Boc, Steven F

    2012-01-01

    Arthrodesis of the first metatarsophalangeal joint (MTPJ) is used primarily for end-stage hallux rigidus whereby pain, crepitus, and limitation of motion is noted at the joint. Arthrodesis at the first MTPJ also has it uses as a primary procedure for rheumatoid arthritis when severe deformity is present, as well as for salvage procedures for failed joint arthroplasties with or without implant, fractures with intra-articular extension, avascular necrosis, and infection management. A first MTPJ arthrodesis should provide stable fixation, attain suitable positioning for a reasonable gait, maintain adequate length, and create a stable platform for a plantigrade foot type. PMID:22243568

  17. Compliant Joints For Robots

    NASA Technical Reports Server (NTRS)

    Kerley, James J., Jr.

    1990-01-01

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

  18. Slip Potential for Commonly Used Inclined Grated Metal Walkways

    PubMed Central

    Pollard, Jonisha P.; Heberger, John R.; Dempsey, Patrick G.

    2016-01-01

    Background No specific guidelines or regulations are provided by the Mine Safety and Health Administration for the use of inclined grated metal walkways in mining plants. Mining and other companies may be using walkway materials that do not provide sufficient friction, contributing to slip and fall injuries. Purpose The purpose of this study was to determine if there are significant differences in the required friction for different grated metal walkways during walking in diverse conditions. Methods The normalized coefficients of friction were measured for 12 participants while walking up and down an instrumented walkway with different inclinations (0°, 5°, 10°, 15°, and 20°) and with and without the presence of a contaminant (glycerol). Self-reported slip events were recorded and the required coefficients of friction were calculated considering only the anterior/posterior components of the shear forces. Additionally, the available coefficients of friction for these walkway materials were measured at the 0° orientation using a tribometer, with and without the presence of the contaminant, using a boot heel as well as Neolite as the test feet. Results The number of slips increased when the inclination angle reached 10° and above. Of all materials tested, the diamond weave grating was found to have the best performance at all inclines and when contaminated or dry. A high number of slips occurred for the perforated grating and serrated bar grating at 20° when contaminated. Conclusions Results of this study suggest that the diamond weave grating provides significantly better friction compared to serrated bar and perforated gratings, especially at inclines greater than 10°. PMID:26779388

  19. Creep versus Earthquake Slip: New insights from rock magnetic data

    NASA Astrophysics Data System (ADS)

    Chou, Y.-M.; Aubourg, C.; Song, S.-R.; Lee, T.-Q.; Song, Y.-F.

    2012-04-01

    Pseudotachylyte is generally believed as the best evidence of high-friction heating during earthquake. However, in clay-rich derived gouge, the temperature elevation is limited to large-scale endothermic dehydration reaction (Brantut et al., 2011). In such a context where melting is likely, it has been suggested that the characterization of neoformed mineral may be a diagnostic clue to distinguish between creep process and earthquake slip zone. Here we show evidence of neoformed magnetic mineral in the active Chelungpu fault gouge that hosts the Chi-Chi slip zone (Taiwan, Mw 7.6, 1999). Thanks to boreholes of Taiwan Chelungpu-fault Drilling Program and the recovery of fresh gouge, we get new evidence of neoformed magnetic minerals. Both rock magnetic investigation and transmission X-ray microscope image show the occurrence of neoformed 5 µm goethite (α-FeOOH) within the Chi-Chi 16 cm thick gouge. Goethite forms post-seismically from the cooling of >350°C fluids. In addition to goethite, we detect occurrence of neoformed pyrrhotite (Fe7S8). The pyrrhotite forms at the expense of pyrite, in response to elevation of temperature >500°C. Within the mm-thick Chi-Chi principal slip zone, we do not detect evidence of goethite, nor pyrrhotite. Instead, we detect magnetite (Fe3O4). We suggest that a part of magnetite formed during friction-induced temperature elevation. We propose a simple model of evolution between goethite and magnetite within the entire gouge. If confirmed elsewhere, the recognition of the assemblage of iron oxide (magnetite), iron hydroxide (goethite) and iron sulfide (pyrrhotite) is possibly a diagnostic evidence of earthquake slip rather than creep process.

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

    PubMed Central

    Florea, Olivia Ana; Roşca, Ileana Constanţa

    2015-01-01

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