Science.gov

Sample records for tube-in-tube slip joint

  1. 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.

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

    E-print Network

    Yang, Lu

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

  3. 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...

  4. 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.

  5. Longitudinal joint systems in slip-formed rigid pavements. Volume 4: Recommendations for alternate joint systems and for strengthening existing joints

    NASA Astrophysics Data System (ADS)

    Korbus, L.; Barenberg, E. J.

    1981-11-01

    Load transfer across joints is a key factor in the performance of PCC pavements. The common load transfer devices in longitudinal joints for airport pavements have for many years been concrete keyways. Many of these keyways fail under heavy aircraft loads and are very difficult to construct using slip-formed pavers. Alternate joint systems which are potentially more reliable than keyways and which can be constructed using slip-formed pavers are presented in the report. Also, procedures are described for retrofitting existing slabs with devices to provide load transfer across joints or cracks. Laboratory and field tests with these load transfer devices are described, and data on their performance are presented. Recommendations for joint designs for PCC airport pavements are given based on the level of traffic anticipated.

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

    PubMed

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

    2014-02-01

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

  7. Analysis of the Region of Validity of Equations for Calculating Heat Exchangers of the Tube-in-Tube Type

    NASA Astrophysics Data System (ADS)

    Moshinskii, A. I.

    2015-09-01

    Based on the traditional model with direct flow and counterflow of heat transfer agents in a stationary regime, the operation of a heat exchanger of the tube-in-tube type is analyzed. Account is taken of the natural limitations for the model that are connected with the possibility of practical realization of the similarity numbers involved in the equations of the model, as well as with the conditions (assumptions) invoked in the derivation of the model. A comparison of the efficiency of heat transfer in the noted regimes of heat transfer agent motions is made. For the purposes of this comparison, it is proposed to use an averaged value of the function that represents the ratio of efficiencies with heat transfer agent direct flow and counterflow over the region of possible values of similarity numbers. The necessary calculations and illustrations are presented.

  8. 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.

  9. 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...

  10. Average boiling and condensation heat transfer coefficients of the zeotropic refrigerant mixture R22/R142b in a coaxial tube-in-tube heat exchanger

    SciTech Connect

    Meyer, J.P.; Bukasa, J.M.; Kebonte, S.A.

    2000-02-01

    Average boiling and condensation heat transfer coefficients were determined experimentally for a coaxial tube-in-tube heat exchanger used in hot water heat pumps. During manufacturing, the heat exchanger geometry used for the experiments changed from round tubes to elliptical tubes as no spacers were used to keep the inner tube from touching the outer tube. The refrigerant used was two different mixtures of R22 with R142b in mass ratios of 80%/20% and 60%/40%. The results were compared to theoretical results for straight tubes. It was concluded that the theoretical modes do not predict the heat transfer coefficients very well in coaxial tube-in-tube heat exchangers where the annulus touches the inside of the outer tube.

  11. 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

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

    SciTech Connect

    Li, Juan; Beijing National Laboratory for Molecular Sciences , State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 ; Que, Tingli; Huang, Jianbin; Beijing National Laboratory for Molecular Sciences , State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871

    2013-02-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  14. Localized fault slip to the trench in the 2010 Maule, Chile Mw = 8.8 earthquake from joint inversion of high-rate GPS, teleseismic body waves, InSAR, campaign GPS, and tsunami observations

    NASA Astrophysics Data System (ADS)

    Yue, Han; Lay, Thorne; Rivera, Luis; An, Chao; Vigny, Christophe; Tong, Xiaopeng; Báez Soto, Juan Carlos

    2014-10-01

    The 27 February 2010, Mw 8.8 Maule earthquake ruptured ~500 km along the plate boundary offshore central Chile between 34°S and 38.5°S. Establishing whether coseismic fault offset extended to the trench is important for interpreting both shallow frictional behavior and potential for tsunami earthquakes in the region. Joint inversion of high-rate GPS, teleseismic body waves, interferometric synthetic aperture radar (InSAR), campaign GPS, and tsunami observations yields a kinematic rupture model with improved resolution of slip near the trench. Bilateral rupture expansion is resolved in our model with relatively uniform slip of 5-10 m downdip beneath the coast and two near-trench high-slip patches with >12 m displacements. The peak slip is ~17 m at a depth of ~15 km on the central megathrust, located ~200 km north from the hypocenter and overlapping the rupture zone of the 1928 M ~8 event. The updip slip is ~16 m near the trench. Another shallow near-trench patch is located ~150 km southwest of the hypocenter, with a peak slip of 12 m. Checkerboard resolution tests demonstrate that correctly modeled tsunami data are critical to resolution of slip near the trench, with other data sets allowing, but not requiring slip far offshore. Large interplate aftershocks have a complementary distribution to the coseismic slip pattern, filling in gaps or outlining edges of large-slip zones. Two clusters of normal faulting events locate seaward along the plate motion direction from the localized regions of large near-trench slip, suggesting that proximity of slip to the trench enhanced extensional faulting in the underthrusting plate.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Stress- and aftershock-constrained joint inversions for coseismic and postseismic slip applied to the 2004 M6.0 Parkfield earthquake

    NASA Astrophysics Data System (ADS)

    Wang, Lifeng; Hainzl, Sebastian; ZöLler, Gert; Holschneider, Matthias

    2012-07-01

    Both aftershocks and geodetically measured postseismic displacements are important markers of the stress relaxation process following large earthquakes. Postseismic displacements can be related to creep-like relaxation in the vicinity of the coseismic rupture by means of inversion methods. However, the results of slip inversions are typically non-unique and subject to large uncertainties. Therefore, we explore the possibility to improve inversions by mechanical constraints. In particular, we take into account the physical understanding that postseismic deformation is stress-driven, and occurs in the coseismically stressed zone. We do joint inversions for coseismic and postseismic slip in a Bayesian framework in the case of the 2004 M6.0 Parkfield earthquake. We perform a number of inversions with different constraints, and calculate their statistical significance. According to information criteria, the best result is preferably related to a physically reasonable model constrained by the stress-condition (namely postseismic creep is driven by coseismic stress) and the condition that coseismic slip and large aftershocks are disjunct. This model explains 97% of the coseismic displacements and 91% of the postseismic displacements during day 1-5 following the Parkfield event, respectively. It indicates that the major postseismic deformation can be generally explained by a stress relaxation process for the Parkfield case. This result also indicates that the data to constrain the coseismic slip model could be enriched postseismically. For the 2004 Parkfield event, we additionally observe asymmetric relaxation process at the two sides of the fault, which can be explained by material contrast ratio across the fault of ˜1.15 in seismic velocity.

  17. 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) straining off the mapped fault traces in NeoKinema, relative to the elastic-microplate models of 2007 WGCEP [2008]. I have not been able to lower the RMS continuum strain rate in these models below 5×10-16 /s (=1.6%/Ma). Such distributed straining results from gaps and geometric incompatibilities in the fault network and from geologic/geodetic discrepancies. This straining probably also occurs on faults (which are not part of WGCEP Fault Models), and it probably also produces earthquakes.

  18. Tube-in-tube thermophotovoltaic generator

    DOEpatents

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

    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.

  19. 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).

  20. 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. A laboratory scale non-contact Electro-Optical Hybrid Slip Ring system was successfully constructed, and its performance was determined. Experimental results affirmed the advantages of this new technology over current slip ring design.

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  10. Behavior of jointed pipelines

    SciTech Connect

    Singhal, A.C.

    1984-06-01

    Experimental data on the axial, bending and torsional behavior of ductile cast iron pipes with rubber gasket joints is presented. Analytical expressions are provided which predict the resistance mechanisms and behavior of the joints. The bending mechanism is found to be quite different from the axial and torsional mechanism. By repeating the tests in a specially designed soil box, the effects of burial depths are determined. A joint stiffness matrix including axial, bending and torsional effects is provided. The slip behavior of the joint changes the stiffness values, however this occurence may be dealt with by using an appropriate flag system placed within a computer program. To minimize axial compressional stresses and interlocking bending stresses at the joint, a minor geometrical change in the joint needs to be made. Joints with larger lip lengths provide more flexibility when subjected to axial compression or joint bending rotations.

  11. Rotary power slips

    SciTech Connect

    Crowe, W.E.

    1987-07-21

    This patent describes rotary power slips, for use in the rotary table of an earth drilling rig, comprising: a body; slip means carried on the body for gripping and releasing pipe in a pipe opening in a rotary table; a stationary air transfer ring supported by the body, and having a primary fluid conduit for connection to a stationary fluid source on the drilling rig, and having a transverse upper surface with at least two concentric grooves; an annular seal ring secured to the body and having a transverse lower surface and an air passageway; expansive means including an expansive ring having inner and outer edges mounted in the grooves on the upper surface of the air transfer ring and cooperative with the lower surface of the seal ring for forming an annular expansive fluid duct to conduct fluid between the primary fluid conduit and the air passageway; a fluid cylinder mounted on the body and fluidly connected to a secondary fluid conduit through the body to the air passageway for raising and lowering the slip means in response to fluid flow through the primary fluid conduit, the air passageway, and the secondary fluid conduit; and a retainer ring in each of the grooves on the upper surface of the air transfer ring, compressed against one of the edges of the expansive ring for locking the expansive ring in place.

  12. 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.

  13. 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.

  14. 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.

  15. SlipChip†

    PubMed Central

    Du, Wenbin; Li, Liang; Nichols, Kevin P.; Ismagilov, Rustem F.

    2009-01-01

    The SlipChip is a microfluidic device designed to perform multiplexed microfluidic reactions without pumps or valves. The device has two plates in close contact. The bottom plate contains wells preloaded with many reagents; in this paper plates with 48 reagents were used. These wells are covered by the top plate that acts as a lid for the wells with reagents. The device also has a fluidic path, composed of ducts in the bottom plate and wells in the top plate, which is connected only when the top and bottom plate are aligned in a specific configuration. Sample can be added into the fluidic path, filling both wells and ducts. Then, the top plate is “slipped”, or moved, relative to the bottom plate so the complementary patterns of wells in both plates overlap, exposing the sample-containing wells of the top plate to the reagent-containing wells of the bottom plate, and enabling diffusion and reactions. Between the two plates, a lubricating layer of fluorocarbon was used to facilitate relative motion of the plates. This paper implements this approach on a nanoliter scale using devices fabricated in glass. Stability of preloaded solutions, control of loading, and lack of cross-contamination were tested using fluorescent dyes. Functionality of the device was illustrated via crystallization of a model membrane protein. Fabrication of this device is simple and does not require a bonding step. This device requires no pumps or valves and is applicable to resource-poor settings. Overall, this device should be valuable for multiplexed applications that require exposing one sample to many reagents in small volumes. One may think of the SlipChip as an easy-to-use analogue of a preloaded multi-well plate, or a preloaded liquid-phase microarray. PMID:19636458

  16. 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.

  17. Mechanism of slip and twinning

    NASA Astrophysics Data System (ADS)

    Rastani, Mansur

    1992-06-01

    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.

  18. {110} Slip with {112} slip traces in bcc Tungsten

    PubMed Central

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

    2013-01-01

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

  19. 46 CFR 56.30-40 - Flexible pipe couplings of the compression or slip-on type.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Flexible pipe couplings of the compression or slip-on...Piping Joints § 56.30-40 Flexible pipe couplings of the compression or slip-on type. (a) Flexible pipe couplings of the compression or...

  20. Micro/macro-slip damping in beams with frictional contact interface

    NASA Astrophysics Data System (ADS)

    Asadi, K.; Ahmadian, H.; Jalali, H.

    2012-10-01

    Friction in contact interfaces of assembled structures is the prime source of nonlinearity and energy dissipation. Determination of the dissipated energy in an assembled structure requires accurate modeling of joint interfaces in stick, micro-slip and macro-slip states. The present paper proposes an analytical model to evaluate frictional energy loss in surface-to-surface contacts. The goal is to develop a continuous contact model capable of predicting the dynamics of friction interface and dissipation energy due to partial slips. To achieve this goal, the governing equations of a frictional contact interface are derived for two distinct contact states of stick and partial slip. A solution procedure to determine stick-slip transition under single-harmonic excitations is derived. The analytical model is verified using experimental vibration test responses performed on a free-frictionally supported beam under lateral loading. The theoretical and experimental responses are compared and the results show good agreements between the two sets of responses.

  1. Blood Flow, Slip, and Viscometry

    PubMed Central

    Nubar, Yves

    1971-01-01

    The viscosity of blood, measured by the usual viscometers in which slip is not considered, is found to be flow dependent, varying markedly with shear rate, pressure gradient, and vessel diameter in the lower ranges of these factors. The study postulates, on grounds thought reasonable, that slip may be present in blood flow, as a function of the nature of the wall surfaces, shear stress at the wall, and relative cell volume (RCV) adjacent to the wall. It presumes that blood possesses a specific, flow-independent viscosity, and determines theoretically the viscosity indications of viscometers if blood slipped in the instruments. The study shows that if the slip function is of a certain plausible form, these viscosity indications would exhibit a flow dependence of much the same pattern as the actual indications supplied by the usual viscometers. The slip postulate permits, therefore, an interpretation of the “anomalous” flow behavior of blood, dispensing with the prevailing assumption of an ad hoc variability of its viscosity with flow factors. To the extent that viscometric data for blood may be representative of other non-newtonian fluids, the slip postulate may be applicable to these fluids. PMID:5573368

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

    SciTech Connect

    Koteras, J.R.

    1991-10-01

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

  5. Velocity slip on curved surfaces

    E-print Network

    Weikang Chen; Rui Zhang; Joel Koplik

    2013-09-05

    The Navier boundary condition for velocity slip on flat surfaces, when expressed in tensor form, is readily extended to surfaces of any shape. We test this assertion using molecular dynamics simulations of flow in channels with flat and curved walls and for rotating cylinders and spheres, all for a wide range of solid-liquid interaction strengths. We find that the slip length as conventionally measured at a flat wall in Couette flow is the same as that for all other cases with curved and rotating boundaries, provided the atomic interactions are the same and boundary shape is properly taken into account. These results support the idea that the slip length is a material property, transferable between different flow configurations.

  6. 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).

  7. Strength or power, which is more important to prevent slip-related falls?

    PubMed

    Han, Longzhu; Yang, Feng

    2015-12-01

    Falls are a serious health and medical concern facing older adults worldwide. Both muscle strength and power have been related to falls among older adults. The primary purpose of this study was to identify which one of these two muscular performances is more important in preventing a slip-related fall. Twenty-six healthy young adults participated in this study. Their muscle strength (torque) and power capacities were assessed at the right knee under maximum voluntary isometric (flexion and extension) and isokinetic (concentric extension and flexion at three different contraction speeds: 60deg/s, 120deg/s, and 180deg/s) contractions, respectively. They were then subjected to an identical and unannounced slip during gait on a treadmill under the protection of a safety harness after walking regularly for five times on the treadmill. Accuracy of predicting slip outcome (fall vs. recovery) was examined for each muscle performance measurement using logistic regression. Results showed that overall the joint power capacity measurements predicted the slip outcome among these subjects with higher accuracy than did the joint torque capacity measurements. Such results suggested that muscle power could be more closely related to a fall initiated by a slip during gait. The findings from the present study could provide guidance to identify individuals at increased risk of falling using the joint power capacity measurement and to design effective fall prevention training paradigms aiming at maximizing muscle power among older adults and others with physical disabilities. PMID:26378820

  8. Bulk Metallic Glasses Deform via Slip Avalanches

    E-print Network

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

    2013-12-21

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

  9. 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.

  10. Hypermobile joints

    MedlinePLUS

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

  11. Origin of Anomalous Slip in Tungsten

    NASA Astrophysics Data System (ADS)

    Marichal, C.; Srivastava, K.; Weygand, D.; Van Petegem, S.; Grolimund, D.; Gumbsch, P.; Van Swygenhoven, H.

    2014-07-01

    Low-temperature deformation of body-centered cubic metals shows a significant amount of plastic slip on planes with low shear stresses, a phenomenon called anomalous slip. Despite progress in atomistic modeling of the consequences of complex stress states on dislocation mobility, the phenomenon of anomalous slip remained elusive. Using in situ Laue microdiffraction and discrete dislocation dynamics in micrometer sized tungsten single crystals, we demonstrate the occurrence of significant anomalous slip. It occurs as a consequence of cross kinks, topological configurations generated by prior dislocation interactions. This clearly identifies anomalous slip as a multidislocation process and not a property of isolated dislocations. The cross-kink mechanism also explains the ambiguous reporting of anomalous slip traces in the past and directs us to ways of including anomalous slip in continuum crystal plasticity formulations.

  12. 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.

  13. Chondrolysis in slipped upper femoral epiphysis. Long-term study of the aetiology and natural history.

    PubMed

    Vrettos, B C; Hoffman, E B

    1993-11-01

    Of 44 patients (55 hips) with slipped upper femoral epiphysis treated from 1963 to 1989, 13 (14 hips) developed chondrolysis. Eight hips had chondrolysis at the time of presentation, all in female patients who were either coloured or black and who had moderate or severe slips. The other six hips had persistent pin penetration of the joint; in five of these the pin penetrated the anterosuperior quadrant of the head. Removal of penetrating pins resulted in improvement in pain in all six hips and in the range of movement in four. Chondrolysis did not develop in any of 11 hips with transient intraoperative pin penetration. In hips with chondrolysis maximum joint-space narrowing developed within the first year; improvement in joint space and range of movement continued for up to three years after maximal involvement. At an average follow-up of 13.3 years no patient had pain but five hips were stiff. PMID:8245091

  14. Process for slip casting textured tubular structures

    DOEpatents

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

    2002-01-01

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

  15. Outcomes following subcapital osteotomy for severe slipped upper femoral epiphysis.

    PubMed

    Vanhegan, I S; Cashman, J P; Buddhdev, P; Hashemi-Nejad, A

    2015-12-01

    Slipped upper femoral epiphysis (SUFE) is the most common hip disorder to affect adolescents. Controversy exists over the optimal treatment of severe slips, with a continuing debate between in situ fixation versus corrective surgery. We present our experience in a series of 57 patients presenting with severe unilateral SUFE (defined > 50°) managed with a subcapital cuneiform osteotomy. Between 2001 and 2011, 57 patients (35 male, 22 female) with a mean age of 13.1 years (9.6 to 20.3, SD 2.3) were referred to our tertiary referral institution with a severe slip. The affected limb was rested in slings and springs before corrective surgery which was performed via an anterior Smith-Petersen approach. Radiographic analysis confirmed an improvement in mean head-shaft slip angle from 53.8(o) (standard deviation (sd) 3.2) pre-operatively to 9.1(o) (sd 3.1) post-operatively, with minimal associated femoral neck shortening. In total 50 (88%) patients were complication free at a mean follow-up of seven years (2.8 to 13.9 years, sd 3). Their mean Oxford hip score was 44 (37 to 48) and median visual analogue pain score was 0 out of 10 (interquartile range 0 to 4). A total of six patients (10.5%) developed avascular necrosis requiring further surgery and one (1.8%) patient developed chondrolysis but declined further intervention. This is a technically demanding operation with variable outcomes reported in the literature. We have demonstrated good results in our tertiary centre. Cite this article: Bone Joint J 2015;97-B:1718-25. PMID:26637690

  16. 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.

  17. Bulk metallic glasses deform via slip avalanches.

    PubMed

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

    2014-04-18

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

  18. 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.

  19. Stick and slip actuators (SSA)

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

  20. Salton Sea Satellite Image Showing Fault Slip

    USGS Multimedia Gallery

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

  1. Slip-controlled thin film dynamics

    E-print Network

    R. Fetzer; M. Rauscher; A. Münch; B. A. Wagner; K. Jacobs

    2006-03-17

    In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various temperatures above the glass transition. We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and 10 microns on DTS covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.

  2. [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.

  3. 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.

  4. Suppression of strike-slip fault zones by preexisting crustal heterogeneities

    NASA Astrophysics Data System (ADS)

    Curren, I. S.; Bird, P.

    2013-12-01

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

  5. 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.

  6. 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

  7. Improved Slip Casting Of Ceramic Models

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.; Vasquez, Peter; Hicks, Lana P.

    1994-01-01

    Improved technique of investment slip casting developed for making precise ceramic wind-tunnel models. Needed in wind-tunnel experiments to verify predictions of aerothermodynamical computer codes. Ceramic materials used because of their low heat conductivities and ability to survive high temperatures. Present improved slip-casting technique enables casting of highly detailed models from aqueous or nonaqueous solutions. Wet shell molds peeled off models to ensure precise and undamaged details. Used at NASA Langley Research Center to form superconducting ceramic components from nonaqueous slip solutions. Technique has many more applications when ceramic materials developed further for such high-strength/ temperature components as engine parts.

  8. 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.

  9. Flow and slip transition in nanochannels.

    PubMed

    Li, Long; Mo, Jingwen; Li, Zhigang

    2014-09-01

    We experimentally investigate the Poiseuille flows in nanochannels. It is found that the flow rate undergoes a transition between two linear regimes as the shear rate is varied. The transition indicates that the nonslip boundary condition is valid at low shear rate. When the shear rate is larger than a critical value, slip takes place and the slip length increases linearly with increasing shear rate before approaching a constant value. The results reported in this work can help advance the understanding of flow slip in nanochannels. PMID:25314525

  10. 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

  11. Joint Commission

    MedlinePLUS

    ... Updates America’s Hospitals: Improving Quality and Safety: The Joint Commission’s Annual Report 2015 Tuesday November 17, 2015 ... Center of Sarasota Read Full Testimonial | Read All Joint Commission Vision All people always experience the safest, ...

  12. 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.

  13. 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, ...

  14. Slip-Mediated Dewetting of Polymer Microdroplets

    E-print Network

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

    2015-07-13

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

  15. Subgrain boundaries and slip systems in quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Khazaei, Cyrus; Hazzard, Jim; Chalaturnyk, Rick

    2015-02-01

    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.

  17. 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 triggered slow-slip on the San Andreas Fault at Parkfield, CA., due to December, 2003 Mw6.5 San Simeon Earthquake (Breguier et al., Science 321, p.1478, 2008) shows very similar characteristics to what we observe in the laboratory, suggesting an extremely low in situ effective stress or a weak fault and a nonlinear-dynamical triggering mechanism.

  18. 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.

  19. 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...

  20. 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...

  1. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  3. Constraining Paleoearthquake Slip Distributions with Coral Microatolls

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  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. 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…

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  7. 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.

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

    USGS Publications Warehouse

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

    2011-01-01

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

  9. 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 earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a 'characteristic earthquake' mode. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

  10. 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

  11. 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

  12. 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 ...

  13. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) An inert gas back-up on the first weld pass. (b) A slip-on welded joint with sleeves and attachment... lengths without flanges must be joined by one of the following: (a) A butt welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld...

  14. Pressure slip casting of silicon nitride

    SciTech Connect

    Richter, H.J.

    1995-09-01

    This paper discusses the potential of pressure slip casting for components made of technical ceramic materials. The tests carried out on pressure slip casting and pressure filtration of silicon nitride show that the highest green density will be obtained if a slurry is used which is completely deflocculated and does not contain any binding agent. Penetration of fine particles into the porous plastic mould cannot be completely prevented but can be reduced to a large extent by the proper selection of the pressure-time regime.

  15. 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.

  16. 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.

  17. Ceramic joints

    DOEpatents

    Miller, Bradley J. (Worcester, MA); Patten, Jr., Donald O. (Sterling, MA)

    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.

  18. 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: 19 mm/yr and 11 km, respectively. We also investigate the effect of elastic heterogeneities on the preferred fault slip rate and locking depth. We use the elastic structure inferred from seismic body wave tomography. The forward model incorporating the effects of elastic heterogeneities is based on the fictitious body force technique of Barbot et al. (2009). As the steady-state interseismic velocity field is computed using a superposition of "seismic" slip in the upper crust and the rigid block motion, these calculations are also relevant for coseismic deformation in heterogeneous elastic media.

  19. 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.

  20. 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).

  1. 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.

  2. Superconducting nanowires as quantum phase-slip junctions

    E-print Network

    Loss, Daniel

    , charge and phase are dual quantum variables. A phase-slip event in a superconducting nanowire changes,5 are inconclusive on this point. B¨uchler et al.6 conclude that successive quantum phase slip (QPS) events canLETTERS Superconducting nanowires as quantum phase-slip junctions J. E. MOOIJ* AND YU. V. NAZAROV

  3. Joint pain

    MedlinePLUS

    ... both rest and exercise are important. Warm baths, massage, and stretching exercises should be used as often ... Does keeping the joint elevated help? Do medicines, massage, or applying heat reduce the pain? What other ...

  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. 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 ...

  6. 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.

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

    USGS Publications Warehouse

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

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. 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.

  10. Frictional slip of granite at hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Blanpied, Michael L.; Lockner, David A.; Byerlee, James D.

    1995-07-01

    Sliding on faults in much of the continental crust likely occurs at hydrothermal conditions, i.e., at elevated temperature and elevated pressure of aqueous pore fluids, yet there have been few relevant laboratory studies. To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, we slid laboratory granite faults containing a layer of granite powder (simulated gouge). Velocity stepping experiments were performed at temperatures of 23° to 600°C, pore fluid pressures PH2O of 0 ("dry") and 100 MPa ("wet"), effective normal stress of 400 MPa, and sliding velocities V of 0.01 to 1 ?m/s (0.32 to 32 m/yr). Conditions were similar to those in earlier tests on dry granite to 845°C by Lockner et al. (1986). 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. We infer that one or more fluid-assisted deformation mechanisms are activated in the second, hydrothermal, regime and operate concurrently with cataclastic flow. Slip in the first (cool and/or dry) regime is characterized by pervasive shearing and particle size reduction. Slip in the second (hot and wet) regime is localized primarily onto narrow shear bands adjacent to the gouge-rock interfaces. Weakness of these boundary shears may result either from an abundance of phyllosilicates preferentially aligned for easy dislocation glide, or from a dependence of strength on gouge particle size. Major features of the granite data set can be fit reasonably well by a rate- and temperature-dependent, three-regime friction constitutive model (Chester, this issue). We extrapolate the experimental data and model fit in order to estimate steady state shear strength versus depth along natural, slipping faults for sliding rates as low as 31 mm/yr. We do this for two end-member cases. In the first case, pore pressure is assumed hydrostatic at all depths. Shallow crustal strength in this case is similar to that calculated in previous work from room temperature friction data, while at depths below about 9-13 km (depending on slip rate), strength becomes less sensitive to depth but sensitive to slip rate. In the second case, pore pressure is assumed to be near-lithostatic at depths below ˜5 km. Strength is low at all depths in this case (<20 MPa, in agreement with observations of "weak" faults such as the San Andreas). The predicted depth of transition from velocity weakening to velocity strengthening lies at about 13 km depth for a slip rate of 31 mm/yr, in rough agreement with the seismic-aseismic transition depth observed on mature continental faults. These 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.

  11. 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.

  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 geometry of this coupling has survived for more than one seismic cycle. It does not however imply that the slip on these earthquakes is predictable; it means simply that there is a low probability that high slip will occur in areas of weak coupling or where high levels of slip already occurred during these shocks.

  13. 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

  14. The bacterial flora of enamel slip

    E-print Network

    Wahlin, Joel G.

    1922-01-01

    alkaline from the soda dissolved from the frit mentioned above and contains humus and other similar organic material from the clay which gives rit the brown color* There is also a small amount of . borax and a trace of sodium fluoride present, both... for growth ana development of many bacteria* 2* There is probably some germicidal action, duo to the alkaline reaction of the - solution and the presence of borates and fluorides (18)* Having thus seen that the bacterial flora of enamel slip...

  15. Slip length crossover on a graphene surface.

    PubMed

    Liang, Zhi; Keblinski, Pawel

    2015-04-01

    Using equilibrium and non-equilibrium molecular dynamics simulations, we study the flow of argon fluid above the critical temperature in a planar nanochannel delimited by graphene walls. We observe that, as a function of pressure, the slip length first decreases due to the decreasing mean free path of gas molecules, reaches the minimum value when the pressure is close to the critical pressure, and then increases with further increase in pressure. We demonstrate that the slip length increase at high pressures is due to the fact that the viscosity of fluid increases much faster with pressure than the friction coefficient between the fluid and the graphene. This behavior is clearly exhibited in the case of graphene due to a very smooth potential landscape originating from a very high atomic density of graphene planes. By contrast, on surfaces with lower atomic density, such as an (100) Au surface, the slip length for high fluid pressures is essentially zero, regardless of the nature of interaction between fluid and the solid wall. PMID:25854252

  16. Bacterial chemotaxis on SlipChip.

    PubMed

    Shen, Chaohua; Xu, Peng; Huang, Zhou; Cai, Dongyang; Liu, Shuang-Jiang; Du, Wenbin

    2014-08-21

    This paper describes a simple and reusable microfluidic SlipChip device for studying bacterial chemotaxis based on free interface diffusion. The device consists of two glass plates with reconfigurable microwells and ducts, which can set up 20 parallel chemotaxis units as duplicates. In each unit, three nanoliter microwells and connecting ducts were assembled for pipette loading of a chemoeffector solution, bacterial suspension, and 1X PBS buffer solution. By a simple slipping operation, three microwells were disconnected from other units and interconnected by the ducts, which allowed the formation of diffusion concentration gradients of the chemoeffector for inducing cell migration from the cell microwell towards the other two microwells. The migration of cells in the microwells was monitored and accurately counted to evaluate chemotaxis. Moreover, the migrated cells were easily collected by pipetting for further studies after a slip step to reconnect the chemoeffector microwells. The performance of the device was characterized by comparing chemotaxis of two Escherichia coli species, using aspartic acid as the attractant and nitrate sulfate as the repellent. It also enables the separation of bacterial species from a mixture, based on the difference of chemotactic abilities, and collection of the cells with strong chemotactic phenomena for further studies off the chip. PMID:24968180

  17. 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.

  18. 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.

  19. 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.

  20. 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 microseconds, while the duration of the quasi-static triggering is from a few seconds to many years. Fault strengthening takes a long time between slips. However, seismic waves may successively induce fault slip and restrict fault self-healing. Fig. 1 Schematic diagram of the direct-shear configuration.

  1. Limited overlap between the seismic gap and coseismic slip of the great 2010 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Lorito, S.; Romano, F.; Atzori, S.; Tong, X.; Avallone, A.; McCloskey, J.; Cocco, M.; Boschi, E.; Piatanesi, A.

    2011-03-01

    The Mw 8.8 mega-thrust earthquake and tsunami that occurred on 27 February 2010 offshore the Maule region, Chile, was not unexpected. A clearly identified seismic gap existed in an area where tectonic loading has been accumulating since the great 1835 earthquake. Here we jointly invert tsunami and geodetic data to derive a robust model for the coseismic slip distribution and induced coseismic stress changes. We compare these with past earthquakes and the preseismic locking distribution, to assess if the Maule earthquake has filled the seismic gap. We find that the main slip patch is located to the north of the gap, overlapping the rupture zone of the Mw 8.0 earthquake that occurred in 1928, with a secondary concentration of slip to the south. The seismic gap was only partially filled and a zone of high preseismic locking remains unbroken, inconsistent with the assumption that distributions of seismic rupture might be correlated with preseismic locking. Moreover, we conclude that increased stress on the unbroken patch may in turn have increased the probability of another major to great earthquake there in the near future.

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

    NASA Astrophysics Data System (ADS)

    McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

    2014-05-01

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

  4. 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.

  5. Geodetic slip rates in the southern San Andreas Fault system: Investigation of the effects of heterogeneous elastic structure

    NASA Astrophysics Data System (ADS)

    Lindsey, E. O.; Fialko, Y.

    2011-12-01

    We investigate the importance of fault geometry and crustal heterogeneity on estimates of slip rates and locking depths of the Southern San Andreas fault (SAF) and San Jacinto fault (SJF). Previous estimates of geodetic slip rates in the Salton Sea region based on dislocation models have generally inferred a higher slip rate on the SAF (21-26 mm/yr) compared to the SJF (12-19 mm/yr). The inferred geodetic slip rate on the SAF is higher than recent geologic estimates representing average slip rates on time scales of 10^4-10^6 years. We investigate to what extent the geodetically inferred slip rate might be biased by incorrect assumptions about the fault geometry and neglect of spatial variations in crustal rigidity. To address this issue, we use a forward model that incorporates heterogeneous elastic moduli computed from the SCEC CVM-H seismic tomography model of Southern California. In our inversions we allow for a non-vertical SAF and a "blind" segment of the SJF, the previously suggested southern continuation of the Clark fault. The models are compared to surface velocities derived from a combination of all available continuous and campaign GPS sites in the region, processed in a consistent North American fixed frame (NAFD), and InSAR data spanning 18 years (1992-2010). These data sources are strongly complementary: while InSAR provides higher spatial resolution in the near-fault region, we find that GPS sites located more than 10 locking depths from the fault are required to resolve the trade-off between locking depth and fault slip rate. The parameter space is examined using an efficient Monte Carlo algorithm which approximates the joint probability distribution for the model parameters and allows for a formal evaluation of uncertainties and trade-offs. We estimate slip rates of 15(+/-2) mm/yr for the Southern San Andreas fault and a total of 23(+/-3) mm/yr for the two closely spaced branches of the southern San Jacinto fault, in reasonable agreement with geologic estimates. The locking depths are estimated at 9(+/-3) km and 16(+/-3) km for the SAF and SJF, respectively. The incorporation of realistic elastic properties serves to increase the estimated locking depths on both faults by 2-3 km, and decreases the estimated slip rate on the San Andreas fault by several mm/yr in comparison to a homogeneous elastic model.

  6. 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.

  7. 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.

  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. Shoulder joint (image)

    MedlinePLUS

    ... is the most freely moving joint of the body. The shoulder joint can move in multiple directions therefore it is less stable than other joints and is more susceptible to injury. Dislocation of the shoulder joint is common and occurs ...

  10. Arthritis: Metacarpophalangeal (MP) Joint

    MedlinePLUS

    ... is completely destroyed, then joint replacement or joint fusion are effective surgical options. The joints can be ... useful, especially for older or less active individuals. Fusion—or making the joint solid—is an effective ...

  11. 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.

  12. Wireless slips and falls prediction system.

    PubMed

    Krenzel, Devon; Warren, Steve; Li, Kejia; Natarajan, Bala; Singh, Gurdip

    2012-01-01

    Accidental slips and falls due to decreased strength and stability are a concern for the elderly. A method to detect and ideally predict these falls can reduce their occurrence and allow these individuals to regain a degree of independence. This paper presents the design and assessment of a wireless, wearable device that continuously samples accelerometer and gyroscope data with a goal to detect and predict falls. Lyapunov-based analyses of these time series data indicate that wearer instability can be detected and predicted in real time, implying the ability to predict impending incidents. PMID:23366815

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. No-Slip Boundary Condition Switches to Partial Slip When Fluid Contains Surfactant

    E-print Network

    Granick, Steve

    the hydrodynamic boundary condition of oil flow from "stick" to "partial slip", provided that the shear stress. When the reduced velocity was sufficiently high, a plateau shear stress was observed, 1.3 N m-2 for 0 but that this is impossible for flow through a pipe. Textbooks and the mathematical descriptions of fluid flow assign

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Darbandi, Payam

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

  2. Tremor during ice stream stick-slip

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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 area ~ 10 m2, bed shear modulus ~ 10 MPa, effective pressure ~ 10 kPa, and state evolution distance ~ 1 ?m. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. We observe that tremor seismic particle velocity amplitudes are greater during the double wait time events that follow skipped events. The physical mechanism responsible for these anomalously high seismic amplitudes may provide a window into near-future subglacial conditions and the processes that occur during ice stream stagnation.

  3. 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

  4. Nature of slip transfer between strike-slip faults: The Eastern Sinai (Egypt) shear zone, Dead Sea Transform

    NASA Astrophysics Data System (ADS)

    Eyal, Yehuda; Eyal, Moshe

    2015-07-01

    The western margin of the Gulf of Elat (Aqaba), a sector of the Dead Sea Transform, is characterized by an N-S striking shear zone with cumulative sinistral (left-lateral) offset of 24 km. The crystalline basement in the study area is unique in its excellent rock and fault exposures forming a >50 km long, shear zone with abundant offset of linear features as well as the contact of the basement with the Infracambrian sub-horizontal peneplain. These features enable accurate measurement of the horizontal and vertical displacements along the major and secondary faults to ±50 m. The small vertical offset of the peneplain surface and a measurement of about 8° net-slip plunge along one of the major faults suggest that along all strike-slip faults, movement was almost pure horizontal slip. Part of this horizontal slip was transferred to neighboring major strike-slip faults by secondary strike-slip faults with negligible loss of displacement. The amount of horizontal slip transferred by normal faults, even in releasing bends, is small due to the high dip angle of these faults. Wide breccia zones and distributed deformation of a small fraction of the horizontal slip is observed when the angle between the strike-slip faults exceeds 30°.

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

    NASA Astrophysics Data System (ADS)

    Fujii, Yushiro; Satake, Kenji

    2013-09-01

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

  6. 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.

  7. 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.

  8. 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 present work we consider the limiting case of stiff discontinuities that only affect the shear strength of the material.

  9. 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.

  10. 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

  11. 49 CFR 229.115 - Slip/slide alarms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... remote control, the wheel slip/slide alarm of each locomotive shall be shown in the cab of the... road service, or continue in road service following a daily inspection, unless the wheel slip/slide protective device of whatever type— (1) Is functioning for each powered axle under power; and (2)...

  12. 49 CFR 229.115 - Slip/slide alarms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... remote control, the wheel slip/slide alarm of each locomotive shall be shown in the cab of the... road service, or continue in road service following a daily inspection, unless the wheel slip/slide protective device of whatever type— (1) Is functioning for each powered axle under power; and (2)...

  13. SLIP: A Symmetric List Processing Language in PL-I.

    ERIC Educational Resources Information Center

    Leaf, William A.

    SLIP (Symmetric List Processing) is a list processing system designed to be added to a higher order language (PL-1 in this version) so that the user has available to him list processing powers. The primary value of such a system is its data handling power. Through SLIP, one can set up lists of data, scan those lists, alter them, and read or write…

  14. 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,…

  15. Fundamental flows with nonlinear slip conditions: exact solutions

    NASA Astrophysics Data System (ADS)

    Ellahi, R.; Hayat, T.; Mahomed, F. M.; Zeeshan, A.

    2010-10-01

    In this article, we use nonlinear slip conditions to investigate three fundamental flows. Constitutive equations of the third grade fluid give rise to nonlinear equations. Exact analytic solutions of the nonlinear equations with nonlinear boundary conditions are developed. Numerical values between the dimensionless third grade and slip parameters are tabulated. Graphs are plotted and discussed.

  16. Slip, Trip, and Fall Injuries Among Nursing Care Facility Workers

    PubMed Central

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

    2015-01-01

    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

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

    E-print Network

    Steinhoff, Heinz-Jürgen

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

  18. 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 (?m/s)] aseismic slip associated with a 20-fold increase of permeability, which transitions to faster slip (~10 ?m/s) associated with reduced dilatancy and micro-earthquakes. Most aseismic slip occurs within the fluid-pressurized zone and obeys a rate-strengthening friction law ?=0.67+0.045ln(vv0) with v0 = 0.1 ?m/s. Fluid injection primarily triggers aseismic slip in this experiment, with micro-earthquakes being an indirect effect mediated by aseismic creep.

  19. 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.

  20. Effective slip over superhydrophobic surfaces in thin channels

    E-print Network

    Feuillebois, François; Vinogradova, Olga I

    2008-01-01

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

  1. Preslip and cascade processes initiating laboratory stick slip

    NASA Astrophysics Data System (ADS)

    McLaskey, Gregory C.; Lockner, David A.

    2014-08-01

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

  2. 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.

  3. 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.

  4. 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.

  5. Slip Line Field Applied To Deep Drawing

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    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.

  6. Slipping and Rolling on an Inclined Plane

    E-print Network

    Aghamohammadi, Cina; 10.1088/0143-0807/32/4/017

    2011-01-01

    In the first part of the article using a direct calculation two-dimensional motion of a particle sliding on an inclined plane is investigated for general values of friction coefficient ($\\mu$). A parametric equation for the trajectory of the particle is also obtained. In the second part of the article the motion of a sphere on the inclined plane is studied. It is shown that the evolution equation for the contact point of a sliding sphere is similar to that of a point particle sliding on an inclined plane whose friction coefficient is $2/7}\\ \\mu$. If $\\mu> 2/7 \\tan\\theta$, for any arbitrary initial velocity and angular velocity the sphere will roll on the inclined plane after some finite time. In other cases, it will slip on the inclined plane. In the case of rolling center of the sphere moves on a parabola. Finally the velocity and angular velocity of the sphere are exactly computed.

  7. Effective slip on textured superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  8. 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.

  9. 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.

  10. Slip-Length Scaling in Large Earthquakes: The Role of Deep-Penetrating Slip below the Seismogenic Layer

    E-print Network

    Shaw, Bruce E.

    Slip-Length Scaling in Large Earthquakes: The Role of Deep-Penetrating Slip below the Seismogenic with earthquake rupture length for lengths far beyond the length scale set by the seismogenic layer be confined to the seismogenic layer, implies that earthquake stress drop increases as a function of rupture

  11. Knee joint replacement

    MedlinePLUS

    Knee joint replacement is surgery to replace a knee joint with a man-made joint. The artificial joint is called a prosthesis . ... cartilage and bone are removed from the knee joint. Man-made pieces are then placed in the ...

  12. Joint Durability Where Next?

    E-print Network

    Joint Durability Where Next? Peter Taylor #12;The problem? · Some joints are deteriorating faster joints · Batch variability · Drainage · Salt treatment · Hand placed #12;Ames, IA · Non-distressed joint Spacing factor: 0.007in w/cm: 0.40 to 0.45 · Distressed joint Spacing factor: 0.005in w/cm: 0.42 - 0

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

    USGS Publications Warehouse

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

    2005-01-01

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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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 ...

  19. Shoulder Joint Replacement

    MedlinePLUS

    .org Shoulder Joint Replacement Page ( 1 ) Although shoulder joint replacement is less common than knee or hip replacement, it is just as successful in relieving joint pain. Shoulder replacement surgery was ?rst performed in ...

  20. Joint Replacement Surgery

    MedlinePLUS

    ... a Clinical Trial Journal Articles Arthritis July 2014 Joint Replacement Surgery: Health Information Basics for You and Your Family What Is Joint Replacement Surgery? Joint replacement surgery is removing a ...

  1. Temporomandibular Joint Disorder

    MedlinePLUS

    ... feeds delivered directly to your desktop! more... Temporomandibular Joint Disorder Article Chapters Temporomandibular Joint Disorder What is ... Updated: November 2008 Previous Next Related Articles: Temporomandibular Joint Disorder (TMD) Are You Biting Off More Than ...

  2. Tactile Feedback of Object Slip Facilitates Virtual Object Manipulation.

    PubMed

    Walker, Julie M; Blank, Amy A; Shewokis, Patricia A; OMalley, Marcia K

    2015-01-01

    Recent advances in myoelectric prosthetic technology have enabled more complex movements and interactions with objects, but the lack of natural haptic feedback makes object manipulation difficult to perform. Our research effort aims to develop haptic feedback systems for improving user performance in object manipulation. Specifically, in this work, we explore the effectiveness of vibratory tactile feedback of slip information for grasping objects without slipping. A user interacts with a virtual environment to complete a virtual grasp and hold task using a Sensable Phantom. Force feedback simulates contact with objects, and vibratory tactile feedback alerts the user when a virtual object is slipping from the grasp. Using this task, we found that tactile feedback significantly improved a user's ability to detect and respond to slip and to recover the slipping object when visual feedback was not available. This advantage of tactile feedback is especially important in conjunction with force feedback, which tends to reduce a subject's grasping forces and therefore encourage more slips. Our results demonstrate the potential of slip feedback to improve a prosthesis user's ability to interact with objects with less visual attention, aiding in performance of everyday manipulation tasks. PMID:25861087

  3. Methods for quantitatively determining fault slip using fault separation

    NASA Astrophysics Data System (ADS)

    Xu, S.-S.; Velasquillo-Martínez, L. G.; Grajales-Nishimura, J. M.; Murillo-Muñetón, G.; Nieto-Samaniego, A. F.

    2007-10-01

    Fault slip and fault separation are generally not equal to each other, however, they are geometrically related. The fault slip ( S) is a vector with a magnitude, a direction, and a sense of the movement. In this paper, a series of approaches are introduced to estimate quantitatively the magnitude and direction of the fault slip using fault separations. For calculation, the known factors are the pitch of slip lineations ( ?), the pitch of a cutoff ( ?), the dip separation ( Smd) or the strike separation ( Smh) for one marker. The two main purposes of this work include: (1) to analyze the relationship between fault slip and fault separation when slickenside lineations of a fault are known; (2) to estimate the slip direction when the parameters Smd or Smh, and ? for two non-parallel markers at a place (e.g., a point) are known. We tested the approaches using an example from a mainly strike-slip fault in East Quantoxhead, United Kingdom, and another example from the Jordan Field, Ector County, Texas. Also, we estimated the relative errors of apparent heave of the normal faults from the Sierra de San Miguelito, central Mexico.

  4. Joint Replacement (Finger and Wrist Joints)

    MedlinePLUS

    ... a Hand Therapist? Media Find a Hand Surgeon Joint Replacement Email to a friend * required fields From * ... name and customize your collection. DESCRIPTION In a joint replacement, the abnormal bone and lining structures of ...

  5. Perception of slipperiness and prospective risk of slipping at work

    PubMed Central

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

    2013-01-01

    Objectives Falls are a leading cause of injury at work, and slipping is the predominant cause of falling. Prior research has suggested a modest correlation between objective measures (such as coefficient of friction, COF) and subjective measures of slipperiness (such as worker perceptions) in the workplace. However, the degree of association between subjective measures and the actual risk of slipping at the workplace is unknown. This study examined the association between perception of slipperiness and the risk of slipping. Methods 475 workers from 36 limited-service restaurants participated in a 12-week prospective cohort study. At baseline, demographic information was collected, participants rated floor slipperiness in eight areas of the restaurant, and work environment factors, such as COF, were measured. Restaurant-level and area-level mean perceptions of slipperiness were calculated. Participants then reported their slip experience at work on a weekly basis for the next 12?weeks. The associations between perception of slipperiness and the rate of slipping were assessed. Results Adjusting for age, gender, body mass index, education, primary language, mean COF, use of slip-resistant shoes, and restaurant chain, each 1-point increase in mean restaurant-level perception of slipperiness (4-point scale) was associated with a 2.71 times increase in the rate of slipping (95% CI 1.25 to 5.87). Results were similar for area-level perception within the restaurant (rate ratios (RR) 2.92, 95% CI 2.41 to 3.54). Conclusions Perceptions of slipperiness and the subsequent rate of slipping were strongly associated. These findings suggest that safety professionals, risk managers and employers could use aggregated worker perceptions of slipperiness to identify slipping hazards and, potentially, to assess intervention effectiveness. PMID:22935953

  6. 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.

  7. The coordinate movement of the interphalangeal joints. A cinematic study.

    PubMed

    Holguín, P H; Rico, A A; Gómez, L P; Munuera, L M

    1999-05-01

    No agreement exists on how coordinate flexion and extension movements of the interphalangeal joints of the long fingers of the hand are performed. A cinematic study in 18 healthy volunteers was done to assess the objective sequence of beginning and ending of movement in the eight free movements of the hand in which these joints flex and extend. The results show that the proximal interphalangeal joint is the one that first initiates the four analyzed movements in which these interphalangeal joints flex and the four movements in which these interphalangeal joints extend. The distal interphalangeal joint is the one that ends first in these two groups of movements. These results confirm that the coordinated movements of the interphalangeal joints may be explained based exclusively on the tendinous system and especially on the setup and balance that exists between the components of the extensor apparatus (longitudinal sliding of the central slip and lateral bands and either the dorsal to palmar or palmar to dorsal displacement of the lateral bands with respect to the rotation axis of the proximal interphalangeal joint). PMID:10335290

  8. Nanoliter multiplex PCR arrays on a SlipChip

    PubMed Central

    Shen, Feng; Du, Wenbin; Davydova, Elena K.; Karymov, Mikhail A.; Pandey, Janmajay

    2010-01-01

    The SlipChip platform was tested to perform high throughput nanoliter multiplex PCR. The advantages of using the SlipChip platform for multiplex PCR include the ability to preload arrays of dry primers, instrument-free sample manipulation, small sample volume, and high throughput capacity. The SlipChip was designed to preload one primer pair per reaction compartment, and to screen up to 384 different primer pairs with less than 30 nanoliters of sample per reaction compartment. Both a 40-well and a 384-well design of the SlipChip were tested for multiplex PCR. In the geometries used here, the sample fluid was spontaneously compartmentalized into discrete volumes even before slipping of the two plates of the SlipChip, but slipping introduced additional capabilities that made devices more robust and versatile. The wells of this SlipChip were designed to overcome potential problems associated with thermal expansion. By using circular wells filled with oil and overlapping them with square wells filled with the aqueous PCR mixture, a droplet of aqueous PCR mixture was always surrounded by the lubricating fluid. In this design, during heating and thermal expansion, only oil was expelled from the compartment and leaking of the aqueous solution was prevented. Both 40-well and 384-well devices were found to be free from cross-contamination, and end point fluorescence detection provided reliable readout. Multiple samples could also be screened on the same SlipChip simultaneously. Multiplex PCR was validated on the 384-well SlipChip with 20 different primer pairs to identify 16 bacterial and fungal species commonly presented in blood infections. The SlipChip correctly identified five different bacterial or fungal species in separate experiments. In addition, the presence of the resistance gene mecA in methicillin resistant Staphylococcus aureus (MRSA) was identified. The SlipChip will be useful for applications involving PCR arrays, and lays the foundation for new strategies for diagnostics, point-of-care devices, and immobilization based arrays. PMID:20446698

  9. Finite fault modeling of oceanic strike-slip earthquakes

    NASA Astrophysics Data System (ADS)

    Aderhold, K.; Abercrombie, R. E.

    2014-12-01

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

  10. Hip joint replacement

    MedlinePLUS

    ... made joint. The artificial joint is called a prosthesis . ... thromboembolic disease in patients undergoing elective hip and knee arthopolasty: Evidence-based guideline and evidence report. American ...

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Yoshioka, Shoichi; Matsuoka, Yoshiko; Ide, Satoshi

    2015-06-01

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

  14. Shape fabric development in rigid clast populations under pure shear: The influence of no-slip versus slip boundary conditions

    NASA Astrophysics Data System (ADS)

    Mulchrone, Kieran F.; Meere, Patrick A.

    2015-09-01

    Shape fabrics of elliptical objects in rocks are usually assumed to develop by passive behavior of inclusions with respect to the surrounding material leading to shape-based strain analysis methods belonging to the Rf/? family. A probability density function is derived for the orientational characteristics of populations of rigid ellipses deforming in a pure shear 2D deformation with both no-slip and slip boundary conditions. Using maximum likelihood a numerical method is developed for estimating finite strain in natural populations deforming for both mechanisms. Application to a natural example indicates the importance of the slip mechanism in explaining clast shape fabrics in deformed sediments.

  15. Tectonic analysis of fault slip data sets

    NASA Astrophysics Data System (ADS)

    Angelier, Jacques

    1984-07-01

    Using data that include the direction and the sense of motion on individual fault surfaces determined by slickenside lineations, it is possible to reconstruct reduced stress tensors that correspond to the orientation of stress axes and to the ratio ? = (?2-?3)/(?1-?3) between principal stress values (?1??2??3, compression being positive). No assumption is made concerning the orientation of fault planes relative to stress axes, so that reactived faults are taken into account as well as newly created ones. Qualitative and quantitative methods for analysis of fault slip data were developed during the last 10 years. The practical limitation of the methods and the necessity for critical field observations are emphasized. These methods can be applied to focal mechanisms of earthquakes. A more complex analysis of heterogeneous data sets, involving an iterative separation of different stress systems, is also discussed. This analysis enables one to distinguish successive faulting events. Careful qualitative study in the field is in all cases essential.

  16. Slipping on an Arbitrary Surface with Friction

    E-print Network

    Felipe González-Cataldo; Gonzalo Gutiérrez; Julio Yañez

    2015-08-07

    The motion of a block slipping on a surface is a well studied problem for flat and circular surfaces, but the necessary conditions for the block to leave (or not) the surface deserve a detailed treatment. In this article, using basic differential geometry, we generalize this problem to an arbitrary surface, including the effects of friction, providing a general expression to determine under which conditions the particle leaves the surface. An explicit integral form for the velocity is given, which is analytically integrable for some cases, and we find general criteria to determine the critical velocity at which the particle immediately leaves the surface. Five curves, a circle, ellipse, parabola, catenary and cycloid, are analyzed in detail. Several interesting features appear, for instance, in the absense of friction, a particle moving on a catenary leaves the surface just before touching the floor, and in the case of the parabola, the particle never leaves the surface, regardless of the friction. A phase diagram that separates the conditions that lead to a particle stopping in the surface to those that lead to a particle departuring from the surface is also discussed.

  17. Comprehensive Analysis of Dewetting Profiles to Quantify Hydrodynamic Slip

    E-print Network

    Oliver Baeumchen; Renate Fetzer; Andreas Muench; Barbara Wagner; Karin Jacobs

    2008-05-28

    Hydrodynamic slip of Newtonian liquids is a new phenomenon, the origin of which is not yet clarified. There are various direct and indirect techniques to measure slippage. Here we describe a method to characterize the influence of slippage on the shape of rims surrounding growing holes in thin polymer films. Atomic force microscopy is used to study the shape of the rim; by analyzing its profile and applying an appropriate lubrication model we are able to determine the slip length for polystyrene films. In the experiments we study polymer films below the entanglement length that dewet from hydrophobized (silanized) surfaces. We show that the slip length at the solid/liquid interface increases with increasing viscosity. The correlation between viscosity and slip length is dependent on the type of silanization. This indicates a link between the molecular mechanism of the interaction of polymer chains and silane molecules under flow conditions that we will discuss in detail.

  18. View from water showing south facade and adjacent boat slips ...

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

    View from water showing south facade and adjacent boat slips (Facility Nos. S375 & S376) - U.S. Naval Base, Pearl Harbor, Boat House, Hornet Avenue at Independence Street, Pearl City, Honolulu County, HI

  19. 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

  20. Supershear Slip Pulse and Off-Fault Damage

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  1. Revealing Slip Bands In A Metal-Matrix/Fiber Composite

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.

    1995-01-01

    Experimental procedure includes heat treatments and metallographic techniques developed to facilitate studies of deformation of metal-matrix/fiber composite under stress. Reveals slip bands, indicative of plastic flow occurring in matrix during mechanical tests of specimens of composite.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  3. 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.

  4. A Numerical Investigation of Fault Slip Triggered by Hydraulic Fracturing

    E-print Network

    Chapter 23 A Numerical Investigation of Fault Slip Triggered by Hydraulic Fracturing Neda Zangeneh during hydraulic fracturing operations, together with the induced seismicity, and corresponding to investigate the relationship between hydraulic fracturing (i.e. fluid injection) and the response

  5. Independence of slip velocities on applied stress in small crystals.

    PubMed

    Maaß, R; Derlet, P M; Greer, J R

    2015-01-21

    Directly tracing the spatiotemporal dynamics of intermittent plasticity at the micro- and nanoscale reveals that the obtained slip dynamics are independent of applied stress over a range of up to ?400 MPa, as well as being independent of plastic strain. Whilst this insensitivity to applied stress is unexpected for dislocation plasticity, the stress integrated statistical properties of both the slip size magnitude and the slip velocity follow known theoretical predictions for dislocation plasticity. Based on these findings, a link between the crystallographic slip velocities and an underlying dislocation avalanche velocity is proposed. Supporting dislocation dynamics simulations exhibit a similar regime during microplastic flow, where the mean dislocation velocity is insensitive to the applied stress. Combining both experimental and modeling observations, the results are discussed in a framework that firmly places the plasticity of nano- and micropillars in the microplastic regime of bulk crystals. PMID:25178931

  6. Fault slip and rupture velocity inversion by isochrone backprojection

    NASA Astrophysics Data System (ADS)

    Festa, Gaetano; Zollo, Aldo

    2006-08-01

    A new technique is proposed here for the retrieval of slip images from the backprojection of high-frequency displacement records. When direct S waves are seen to be dominant in the near-source data, Green functions can be approximated by the far-field terms, as described by ray theory. Assuming that the slip rapidly reaches the final value (i.e. short slip duration), the measured displacement can be ascribed to the slip contributions lying on the corresponding isochrone on the fault plane. Here we use the far-field representation theorem to backproject on the fault plane the displacement amplitudes measured along the seismogram. Through the weighted stack of amplitude maps obtained from different stations we recover high slip zones on the fault. The resolution analysis of the backprojected images is realized with spike tests (that we refer to as `image Green functions'), which revealed to be an useful tool for detecting and locating artificial distortions of high slip patches, due to a poor data coverage. However, when the slip is uniformly spread along the isochrones, energy is scattered everywhere on the fault, leading to defocusing effects on the final images. A partial deconvolution technique is proposed by reiterating the backprojection. An important implication of this study is that slip maps can be obtained as functions of the rupture time on the fault, that is, the method can be used to retrieve variable rupture velocity kinematic models. Since the latter parameter is not known a priori, we suggest that a data set of coupled rupture velocity and slip maps is built up and the optimal model is chosen according to a waveform fitness criterion. This procedure allows the slip inversion to be separated from the rupture velocity inversion, significantly reducing the number of parameters to be estimated. Additionally, the parametrization of the rupture velocity is done on a less dense grid than the slip. By way of example, the technique is applied to estimation of the kinematic rupture model of the 2000 Tottori earthquake (M = 6.8), based on the inversion of near-source strong-motion data.

  7. Fluctuation in entanglement positions via elastic slip-links Jay D. Schieber1,a

    E-print Network

    Schieber, Jay D.

    Fluctuation in entanglement positions via elastic slip-links Jay D. Schieber1,a and Kazushi Horio1 of slip-link positions via the implementation of elastic slip-links. The level of description is similar to our previously proposed slip-link model, wherein we use the entanglement position in space as dynamic

  8. Influence of slip on vortex-induced motion of a superhydrophobic cylinder

    E-print Network

    Rothstein, Jonathan

    Influence of slip on vortex-induced motion of a superhydrophobic cylinder Robert Daniello, Pranesh: Superhydrophobic Ultrahydrophobic Superhydrophobicity Slip Partial slip Drag reduction Vortex Cylinder a b s t r a c t The partial slip boundary condition produced by a superhydrophobic surface in the Cassie state

  9. 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.

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

    PubMed Central

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

    2014-01-01

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

  11. Origins of oblique-slip faulting during caldera subsidence

    NASA Astrophysics Data System (ADS)

    Holohan, Eoghan P.; Walter, Thomas R.; SchöPfer, Martin P. J.; Walsh, John J.; Wyk de Vries, Benjamin; Troll, Valentin R.

    2013-04-01

    Although conventionally described as purely dip-slip, faults at caldera volcanoes may have a strike-slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural calderas. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (2) horizontal translation arising from off-centered or "asymmetric" subsidence. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during caldera subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.

  12. 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 ? = ?hy/?th and the ratio of pore pressure generated to temperature rise buffered by the reaction Pr/Er.

  13. CYCLIC MOTION ENCODING FOR ENHANCED MR VISUALIZATION OF SLIP INTERFACES

    PubMed Central

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

    2010-01-01

    Purpose To develop and test an MRI-based method for assessing the mechanical shear connectivity across tissue interfaces with phantom experiments and in vivo feasibility studies. Materials and Methods External vibrations were applied to phantoms and tissue and the differential motion on either side of interfaces within the media was mapped onto the phase of the MR images using cyclic motion encoding gradients. The phase variations within the voxels of functional slip interfaces reduced the net magnitude signal in those regions, thus enhancing their visualization. A simple two-compartment model was developed to relate this signal loss to the intravoxel phase variations. In vivo studies of the abdomen and forearm were performed to visualize slip interfaces in healthy volunteers. Results The phantom experiments demonstrated that the proposed technique can assess the functionality of shear slip interfaces and they provided experimental validation for the theoretical model developed. Studies of the abdomen showed that the slip interface between the small bowel and the peritoneal wall can be visualized. In the forearm, this technique was able to depict the slip interfaces between the functional compartments of the extrinsic forearm muscles. Conclusion Functional shear slip interfaces can be visualized sensitively using cyclic motion encoding of externally applied tissue vibrations. PMID:19787735

  14. 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 .

  15. Scaling of micro-slip in tangentially loaded rock contact

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  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. Regional Slip Tendency Analysis of the Great Basin Region

    SciTech Connect

    Faulds, James E.

    2013-09-30

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

  18. 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 smaller slip followed by larger slip with opposite sense, the d- x profile would be flatter with no reverse displacement at the tips. Reactivation also decreases the ratio of dmax/ L since for an original right-lateral fault, left lateral reactivation will reduce the net displacement ( dmax) along a fault and increase the fault length ( L). Finally we compare Crackington Haven faults with these in the Atacama system of northern Chile. The Salar Grande Fault (SGF) formed as a left-lateral fault with large displacement in its central region. Later right-lateral reactivation is preserved at the fault tips and at the smaller sub-parallel Cerro Chuculay Fault. These faults resemble those seen at Crackington Haven.

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

    USGS Publications Warehouse

    Dieterich, J.H.

    1987-01-01

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

  20. 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.

  1. Slip Running Reconnection in Magnetic Flux Ropes

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  3. 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 importantly, our simulations demonstrate that the mechanical configuration of the seismogenic layer within which faults are embedded affects how slip is distributed along single fault geometries and partitioned across zones with multiple fault strands. Variability in the depth of the velocity-weakening/velocity-strengthening interface appears to control the magnitude of single-event surface slip. These results shed light on the ability to confidently interpret paleoseismic and topographic records of the magnitude and recurrence of earthquakes, especially in relation to slip in a single earthquake. This is an especially important insight for efforts such as the Uniform California Earthquake Rupture Forecast (UCERF3) that aim to use lidar-derived slip in the most recent event as geologic constraints for expected slip magnitudes of future earthquakes but without accounting for the detailed lithology and structure of a fault zone.

  4. Pressure suit joint analyzer

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  5. Global Morphological Mapping of Strike-Slip Structures on Ganymede

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Many inferences of strike-slip faulting and distributed shear zones on Ganymede suggest that strike-slip tectonism may be important to the structural development of its surface and in the transition from dark to light (grooved) materials. To better understand the role of strike-slip tectonism in shaping Ganymede's multifaceted surface, we identify and map key examples of strike-slip morphologies (en echelon structures, strike-slip duplexes, laterally offset pre-existing features, and possible strained craters) from Galileo and Voyager images. Here we present the current state of these global mapping efforts, with particular emphasis given to complex structures associated with grooved terrain (e.g. Nun Sulci) and terrains transitional from dark to light terrain (e.g. the boundary between Nippur Sulcus and Marius Regio). These results are being synthesized into a global database representing an inferred sense of shear for fractures on Ganymede. This, combined with existing observations of extensional features, is helping to narrow down the range of possible principal stress directions that could have acted at the regional or global scale to produce grooved terrain. Moreover, these data sets, combined with mechanical models of shear failure and global stress sources, are providing constraints for testing possible mechanisms for grooved terrain formation on Ganymede.

  6. 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.

  7. 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(?-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.

  8. Simple calculation measures NH sub 3 slip for cogeneration units

    SciTech Connect

    Anderson, C.M.; Billings, J.A. )

    1991-04-01

    This paper reports that government regulations restricting NO{sub x} emissions for New Stationary Sources have brought about an increased demand for deNO{sub x} systems. One such system is selective catalytic reduction (SCR). It uses ammonia in the presence of a catalyst to selectively reduce NO{sub x} emissions. Because of inherent inefficiencies in the SCR design, a small amount of NH{sub 3} slip becomes an additional exhaust stream pollutant discharged into the atmosphere. This discharge requires monitoring. Normally, ammonia is listed as a pollutant in the environmental permit to construct when an SCR system is specified for NO{sub x} reduction. Therefore, a method to report NH{sub 3} slip also will be required. Although the Code of Federal Regulations 40 CRF 60 does not specifically addressed NH{sub 3} slip, state agencies usually require reporting of NH{sub 3} emissions. An ammonia analyzer usually is installed for the measurement. However, other methods to monitor NH{sub 3} slip should be considered. One alternative is to calculate it. A cogeneration plant equipped with SCR using a specific configuration of instrumentation hardware and software will allow the NH{sub 3} slip to be calculated accurately.

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

    DOEpatents

    Cleveland, Joe R. (West Hills, CA)

    1997-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Joint Aspiration (Arthrocentesis)

    MedlinePLUS

    ... Kids Deal With Bullies Pregnant? What to Expect Joint Aspiration (Arthrocentesis) KidsHealth > Parents > Doctors & Hospitals > Medical Tests & Exams > Joint Aspiration (Arthrocentesis) Print A A A Text Size ...

  15. Large displacement spherical joint

    DOEpatents

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

    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.

  16. 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 ...

  17. 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 ...

  18. Hip joint injection

    MedlinePLUS

    ... injection is a shot of medicine into the hip joint. The medicine helps relieve pain and inflammation. It ... often caused by: Bursitis Arthritis Injury to the hip joint or surrounding area Overuse or strain from running ...

  19. Multiscale Stick-Slip Dynamics of Adhesive Tape Peeling.

    PubMed

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

    2015-09-18

    Using a high-speed camera, we follow the propagation of the detachment front during the peeling of an adhesive tape from a flat surface. In a given range of peeling velocity, this front displays a multiscale unstable dynamics, entangling two well-separated spatiotemporal scales, which correspond to microscopic and macroscopic dynamical stick-slip instabilities. While the periodic release of the stretch energy of the whole peeled ribbon drives the classical macro-stick-slip, we show that the micro-stick-slip, due to the regular propagation of transverse dynamic fractures discovered by Thoroddsen et al. [Phys. Rev. E 82, 046107 (2010)], is related to a high-frequency periodic release of the elastic bending energy of the adhesive ribbon concentrated in the vicinity of the peeling front. PMID:26431019

  20. Slip-boundary equations for multicomponent nonequilibrium airflow

    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. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations by 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 airflow, includes the finite-rare 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 and binary mixtures and single-species gas. An expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in the absence of slip.

  1. 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.

  2. 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.

  3. Large apparent slip at a moving contact line

    NASA Astrophysics Data System (ADS)

    Qian, Bian; Park, Joonsik; Breuer, Kenneth S.

    2015-09-01

    Two different particle tracking velocimetry techniques are used to measure the fluid velocities close to the substrate in the vicinity of both receding and advancing contact lines. The slip velocity is found to be as much as 60% of the substrate speed near the contact line and persists as far as 10 ?m from the liquid-gas interface. The estimated slip length near the contact line singularity requires a measurement of the shear rate close the substrate which depends strongly on the spatial resolution of the measurement technique. The slip length is found to be approximately 5 ?m when flood illumination is used and approximately 500 nm when total internal reflection fluorescence illumination is used.

  4. Precursory Processes during Stick-Slip Experiments on Crustal Rocks

    NASA Astrophysics Data System (ADS)

    Passelègue, F. X.; Latour, S.; Schubnel, A.; Nielsen, S. B.; Bhat Suresh, H.; Madariaga, R. I.

    2014-12-01

    Recent seismological observations have highlighted increasing foreshock activity preceding the failure of large earthquakes. Foreshock sequences are the signature of a precursory slip during the nucleation of earthquakes, as observed both prior the Tohoku-Oki Mw 9.0 and the recent Iquique 2014 Mw 8.1 earthquakes. However, foreshocks are not systematic and the reason why they occur remains poorly understood. Recent advances in laboratory experiments allow to mimic seismic ruptures and to study the earthquake nucleation phase. Here, we track the occurrence of foreshocks prior to stick-slip instabilities in crustal rocks. Here we present the results of 6 experiments on saw cut granite samples submitted to triaxial loading under in-situ upper crustal condition that provide additional clues to understand the physical processes of foreshock dynamics. We obtained a catalog of more than 200 stick-slip cycles, composed of loading period and mainshock. Thirty STick-slip Events (STE) are preceded by a foreshock sequence. The moment and location of the 900 measured foreshocks are obtained using acoustic emission (AE) monitoring. We systematically observed that (i) the static friction coefficient, (ii) the stress drop and, consequently, (3) the moment magnitude (and total seismic slip) of the mainshock increases with increasing ?n. In our experiments, an exponential acceleration of the precursory slip is systematically observed, but foreshocks are only observed when the normal stress becomes greater than 55MPa. This threshold corresponds to the normal stress above which the nucleation length becomes comparable to the size of typical fault asperities. In these conditions, the total cumulative moment of the foreshock sequence also increases exponentially up to failure, and the fault surface evolves like a cascading asperity model. This exponential growth implies that the nucleation phase has a characteristic time, i.e. that the foreshock sequence duration and moment release scales with the size of the main asperity which is eventually going to rupture.

  5. Possible Stick-Slip Mechanism for Whillans Ice Stream

    NASA Technical Reports Server (NTRS)

    Bindschadler, Robert; King, Matt; Vornberger, Patricia

    2003-01-01

    Tidally-induced stick-slip motion in the mouth of Whillans Ice Stream provides a unique natural experiment in ice-stream response behavior and from which we might learn a great deal about subglacial till properties and sub-ice-stream conditions. At the IGS Symposium on Fast Glacier Flow (Yakutat, 2002), we reported our observations of stick- slip motion and demonstrated its synchronicity with tidal forcing. Recently, we have completed additional processing of our GPS data in differential mode. It reveals more details of the stick-slip events and illustrates that within 30 seconds, the temporal interval of our data, the ice stream accelerates to a speed corresponding to a completely lubricated bed. While details of individual events vary, there seems to be strong evidence of an elastic rebound on the time scale of one hour following most events. This suggests the event involves the release of stored elastic strain energy in the ice. The similar displacements of events suggest further that till or subglacial hydrologic properties limit the amount of elastic strain released in any single event. We follow a line of reasoning that dilatant strengthening limits the slip displacement and present model of the stick-slip process. To match the observed delay between the peak ocean tide and stick-slip events, our model includes a propagating pressure wave in the subglacial hydrologic system between the grounding line, where the rising tide first increases the subglacial water pressure and regions upstream where stored elastic strain increases the basal shear stress. This high-tide event is released when the increased water pressure reaches the region of increased shear stress. Dilatant strengthening stops the event by increasing pore volume and lowering the water pressure. Following this event, falling tide increases the normal forces, compresses the till and increases pore pressure again, leading to the second falling-tide event we observe every tidal cycle.

  6. Possible Stick-Slip Mechanism for Whillans Ice Stream

    NASA Technical Reports Server (NTRS)

    Bindschadler, Robert; King, Matt; Vornberger, Patricia

    2003-01-01

    Tidally-induced stick-slip motion in the mouth of Whillans Ice Stream provides a unique natural experiment in ice-stream response behavior and fiom which we might learn a great deal about subglacial till properties and sub-ice-stream conditions. At the IGS Symposium on Fast Glacier Flow (Yakutat, 2002), we reported our observations of stick- slip motion and demonstrated its synchronicity with tidal forcing. Recently, we have completed additional processing of our GPS data in differential mode. It reveals more details of the stick-slip events and illustrates that within 30 seconds, the temporal interval of our data, the ice stream accelerates to a speed corresponding to a completely lubricated bed. While details of individual events vary, there seems to be strong evidence of an elastic rebound on the time scale of one hour following most events. This suggests the event involves the release of stored elastic strain energy in the ice. The similar displacements of events suggest further that till or subglacial hydrologic properties limit the amount of elastic strain released in any single event. We follow a line of reasoning that dilatant strengthening limits the slip displacement and present model of the stick-slip process. To match the observed delay between the peak ocean tide and stick-slip events, our model includes a propagating pressure wave in the subglacial hydrologic system between the grounding line, where the rising tide first increases the subglacial water pressure and regions upstream where stored elastic strain increases the basal shear stress. This high-tide event is released when the increased water pressure reaches the region of increased shear stress. Dilatant strengthening stops the event by increasing pore volume and lowering the water pressure. Following this event, falling tide increases the normal forces, compresses the till and increases pore pressure again, leading to the second falling-tide event we observe every tidal cycle.

  7. 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…

  8. 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.

  9. Quantum Phase Slips and Transport in Ultrathin Superconducting Wires

    SciTech Connect

    Zaikin, A.D.; Zaikin, A.D.; Golubev, D.S.; van Otterlo, A.; van Otterlo, A.; Zimanyi, G.T.

    1997-02-01

    We present a microscopic study of the quantum fluctuations of the superconducting order parameter in thin homogeneous superconducting wires at all temperatures below T{sub c}. The rate of quantum phase-slip processes determines the resistance R(T) of the wire, which is observable in very thin wires, even at low temperatures. Furthermore, we predict a new low-temperature metallic phase below a critical wire thickness in the 10-nm range, in which quantum phase slips proliferate. {copyright} {ital 1997} {ital The American Physical Society}

  10. 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.

  11. 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.

  12. 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 based on rapid sealing of faults. Nature 358, 574-576 Sibson, R.H., 1973. Interactions between temperature and pore fluid pressure during earthquake faulting: A mechanism for partial or total stress relief. Nature 243, 66-68. Sleep, N.H., Blanpied, M.L., 1992. Creep, compaction and the weak rheology of major faults. Nature 359, 687-692.

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

    NASA Astrophysics Data System (ADS)

    Melgar, D.; Bock, Y.

    2014-12-01

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

  14. Slips,Trips and Falls RISK MANAGEMENT BULLETINWINTER 2014

    E-print Network

    Kavanagh, Karen L.

    Insurance Exchange REDUCING/MINIMIZING SLIPS,TRIPS AND FALLS 1. HOUSEKEEPING: a) Cleaning all spills. DOCUMENTATION a) Have snow and ice removal and housekeeping policies in place with detailed procedures. b) Under those policies, workers should be required to document their snow/ ice removal and housekeeping

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

    E-print Network

    Read, Andrew

    Synopsis When Malaria Slips a Vaccine's Net Caitlin Sedwick* Freelance Science Writer, San Diego is currently being made to develop vaccines against the parasite. But here, too, the organism's adaptability works against us. Many malarial vaccines work by exposing people to a single purified parasite protein

  16. Mills Library Book Locator Slip Mills Bookstacks Other Mills Locations

    E-print Network

    Thompson, Michael

    Mills Library Book Locator Slip Mills Bookstacks Other Mills Locations Call Numbers... A ­ BX * C ___________________ * BF 1-990 - Thode Library BF 1001-2055 - Mills Library ** All journals on microfilm are housed in Mills Library on the 3rd floor, regardless of call number December 2013 Rev. 09/10 #12;

  17. Mills Library Book Locator Slip Mills Bookstacks Other Mills Locations

    E-print Network

    Thompson, Michael

    Mills Library Book Locator Slip Mills Bookstacks Other Mills Locations Call Numbers... A ­ BX * C Library Lower Level ___________________ * BF 1-990 - Thode Library BF 1001-2055 - Mills Library ** All journals on microfilm are housed in Mills Library on the 3rd floor, regardless of call number December 2013

  18. Slip, Trip and Fall Prevention for Healthcare Workers

    MedlinePLUS

    ... type Slip, Trip, and Fall Prevention? | ?3 An analysis of workers’ compensation injury claims from acute-care ... oil, cleaning solutions, coffee, body fluids)? Are dry contaminants present (powder, sawdust, dirt, flour, food, wax chips)? Are there sudden changes in indoor ...

  19. Two-plane balance and slip-ring design

    NASA Technical Reports Server (NTRS)

    Luna, P. M.

    1985-01-01

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

  20. 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

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

    USGS Publications Warehouse

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

    2005-01-01

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

  2. Orientation and temperature dependence of slip systems in Cd single crystals

    SciTech Connect

    Ucar, N.; Karaman, I.; Duezguen, B.

    1995-05-01

    The orientation and temperature dependence of slip in Cd single crystals has been investigated in tension in the temperature range from room temperature to 480 K. At room temperature, slip occurs along <11{bar 2}0> directions on the basal plane regardless of crystals orientation. On the other hand, above 350 K operative slip directions are found to be depending on crystal orientation and slip planes.

  3. Strike-slip Faulting On Ganymede, Now And Then

    NASA Astrophysics Data System (ADS)

    Pappalardo, Robert T.; Smith-Konter, B. R.; Cameron, M. E.; DeRemer-Keeney, L. C.; Nimmo, F.

    2012-10-01

    Strike-slip tectonism is important to the structural development of Ganymede’s surface, and in the transition from dark to grooved terrain. Three distinct signatures of strike-slip faulting are recognized [1]: (1) en echelon structures, (2) strike-slip duplexes, and (3) laterally offset pre-existing features. As strike-slip faulting progressed, en echelon fractures (in both dark and grooved terrains) merged to define en echelon swaths, which can become distinct tectonic domains. Three morphological categories of strike-slip “duplexes” (spindle-shaped lensoid regions bounded by strike-slip faults) occur, suggesting an evolutionary sequence from discontinuous fractures in dark terrain, to lensoid bounding structures, to lensoid regions with subparallel internal structure in grooved terrain. Ganymede’s 24 measured duplexes have an average length/width ratio of 2.4, on the low end of the terrestrial range [2]. Lateral offsets of pre-existing features betray the existence of some major strike-slip faults: Dardanus Sulcus (13°W, 18°S) is displaced 45 km by a prominent NE-SW trending fault. We model Coulomb shear failure on Ganymede, considering nonsynchronous rotation (NSR), and diurnal stresses both for present (0.0013) and possible past high ( 0.05) eccentricity [3]. We adopt NSR period 0.14 Ma; Love numbers h2 = 1.52 and l2 = 0.38; Young’s modulus 9.3 GPa; Poisson’s ratio 0.33; and fault depth 2 km. NSR shear stress resolved along the Dardanus fault is 0.3 MPa, sufficient to induce failure to 1.4 km for friction coefficient 0.3. For past high eccentricity, diurnal stress would have modulated NSR stress by 100 kPa through Ganymede’s tidal cycle. This could have induced shear heating [4] and tidal walking [5], as modeled for Europa. References: [1] DeRemer and Pappalardo (2003), LPSC, 34, #2033; [2] Aydin and Nur (1982), Tectonics, 1, 91; [3] Showman and Malhotra (1997), Icarus, 127, 93; [4] Nimmo and Gaidos (2002), JGR, 107, 10.1029/2000JE001476; [5] Rhoden et al. (2012), Icarus, 218, 297.

  4. Regional Slip Tendency Analysis of the Great Basin Region

    DOE Data Explorer

    Faulds, James E.

    2013-09-30

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

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

    NASA Technical Reports Server (NTRS)

    Wright, C. Wayne

    2009-01-01

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

  6. Fault-Wear Under Constant Slip-Velocity: Experimental Observations

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  7. Global seismicity characteristics of subduction-to-strike-slip transitions

    NASA Astrophysics Data System (ADS)

    Bilich, Andria; Frohlich, Cliff; Mann, Paul

    2001-09-01

    There are at least 30 major plate boundary segments worldwide where the plate boundary changes from subduction to strike-slip; these include six triple junctions and 24 two-plate boundaries. This study investigates earthquake seismicity in the 24 two-plate subduction-to-strike-slip transition (SSST) regions by utilizing recently published earthquake relocations, ternary diagrams of focal mechanisms, and moment rate calculations. To facilitate cross-regional comparisons, we categorize the geometry of SSST plate boundaries in terms of (1) their radius of curvature, (2) their sense of curvature, that is, whether they are convex or concave as viewed from the downgoing plate, and (3) their tectonic complexity, that is, the variability of crustal thickness and the segmentation of the plate boundary trace. We observe three main trends in SSST regions: (1) there is a conspicuous scarcity of strike-slip earthquakes along plate boundary segments that plate motion models indicate are strike-slip boundaries; (2) in these apparent strike-slip segments, both the rate of occurrence of earthquakes of any kind and the moment release rate are low compared to adjacent subduction segments; and (3) there were few observable differences in seismicity between convex and concave boundaries. The observation that transform zones exhibit moment rate deficiencies, that is, have few large-magnitude earthquakes in the historical record, may have important implications for seismic hazard assessment in SSST regions. In particular, is motion along these boundaries aseismic with little seismic hazard, or is motion expressed in very large magnitude, infrequent, but potentially devastating earthquakes? In at least three such regions, New Zealand, the Philippines, and the Dominican Republic, paleoseismic evidence and the historical record of seismicity suggest that very large, infrequent earthquakes do occur.

  8. Aftershock slip behavior of the 1989 Loma Prieta, California earthquake

    SciTech Connect

    Oppenheimer, D.H. )

    1990-07-01

    An analysis of 745 aftershocks of the M7.1 Loma Prieta earthquake of 17 October, 1989 reveals a wide variety of focal mechanisms. At the northwestern end of the aftershock zone earthquakes that apparently occurred off the main rupture plane exhibit mechanisms with predominantly reverse slip on planes nearly parallel to the San Andreas fault. At the southeastern end the mechanisms exhibit right-lateral motion on near-vertical planes, suggesting that these aftershocks involve slip on the San Andreas fault. Few of the aftershock mechanisms in the central zone resemble the main shock mechanism (strike N130{degree}E, dip 70{degree}SW, rake 104{degree}), but instead exhibit reverse, right-lateral, left-lateral, and normal motion on planes subparallel to the main shock rupture plane. The dip of the aftershock zone is parallel to the main shock slip plane and includes the main shock hypocenter. However, the lack of agreement between the main shock and the aftershock mechanisms suggests that few of the aftershocks occurred on the main shock slip plane. This behavior is consistent with observations of aftershock sequences for other dip-slip events and also with studies indicating that main shock rupture zones are at all other times mostly aseismic. If the stress drop for the main shock relieved most of the tectonic stress, the mechanisms could reflect the heterogeneity of the near-field stress redistribution. Alternatively the variety of the aftershock mechanisms may reflect deformation by block motion within a narrow zone adjacent to the main shock rupture plane.

  9. 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.

  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. The liquid metal slip ring experiment for the communications technology satellite

    NASA Technical Reports Server (NTRS)

    Lovell, R. R.

    1972-01-01

    The experiment is designed to demonstrate liquid metal slip ring (LMSR) performance in a space environment. An evaluation was made of the features of the LMSR where improvement in performance over conventional slip rings was expected. The primary measurements to be made in the experiment will allow a determination of the slip ring electrical resistance, between ring insulation and ring cleanliness.

  12. Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake

    E-print Network

    Vigny, Christophe

    Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake Fred F. Pollitz by the February 27, 2010 Mw = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip. (2011), Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake, Geophys

  13. Fault Wear by Damage Evolution During Steady-State Slip VLADIMIR LYAKHOVSKY,1

    E-print Network

    Lyakhovsky, Vladimir

    Fault Wear by Damage Evolution During Steady-State Slip VLADIMIR LYAKHOVSKY,1 AMIR SAGY,1 YUVAL BONEH,2 and ZE'EV RECHES 3 Abstract--Slip along faults generates wear products such as gouge layers of these zones appar- ently control fault strength and slip stability. Here we present a new model of wear

  14. 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.

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

    SciTech Connect

    Faulds, James E.

    2013-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Mechanics of Suture Joints

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  18. 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.

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

    SciTech Connect

    Faulds, James E.

    2013-12-31

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

  20. Geometric and mechanical-stiffness controls on jointing in cataclastic deformation bands

    NASA Astrophysics Data System (ADS)

    Tindall, Sarah; Eckert, Andreas

    2015-08-01

    Cataclastic deformation bands on the Waterpocket Fold in southern Utah contain cross-cutting joints that terminate at the contacts between the deformation bands and surrounding sandstone. The mechanical contrast between sandstone host rock and stronger deformation bands is analogous to inter-bedded weak and strong layers in a sedimentary sequence, a situation known to result in joints preferentially forming in the stronger layers with joints perpendicular to layer boundaries. Deformation bands in the field area represent conjugate strike-slip shear zones, many with internal Riedel shear geometry, creating a three-dimensional network of mechanically strong zones in variable orientations. Joint attitudes were found to vary systematically as a function of deformation band strike, and the angle between each deformation band and its associated joints is perpendicular to neither the deformation band nor the far-field extension direction. Field observations are confirmed by 2D finite element models showing that local stress reorientation at boundaries between layers affects the mechanics of jointing. The stiffness contrast results in conditions for initiating joints contained in the deformation band, and also results in variable joint orientations in deformation bands with strike orientations oblique to the far-field extension direction. A higher stiffness contrast results in a greater angle between deformation band strike and band-contained joint strike.

  1. Crystal Plasticity Finite-Element Analysis of Deformation Behavior in Multiple-Grained Lead-Free Solder Joints

    NASA Astrophysics Data System (ADS)

    Darbandi, P.; Bieler, T. R.; Pourboghrat, F.; Lee, Tae-kyu

    2013-02-01

    The elastic and plastic anisotropy of the tin phase in a Pb-free tin-based solder joint has a very important effect on the reliability of solder joints. The crystal plasticity finite-element (CPFE) method takes into account the effect of anisotropy, and it can be used to solve crystal mechanical deformation problems under complicated external and internal boundary conditions imposed by inter- and intragrain micromechanical interactions. In this study, experimental lap-shear test results from the literature are used to calibrate the CPFE model. The spatial neighbor orientation relationships of the crystals were assessed by studying four different sets of orientations using a very simple model to establish a basis for further development of the model. Average shear strain and Schmid factor analyses were applied to study the activity of slip systems. Further optimization of model parameters using comparisons with experiments will be needed to identify more suitable rules for stress evolution among the 10 slip systems in Sn. By suppression of some of the slip systems the CPFE model is able to simulate heterogeneous deformation phenomena that are similar to those observed in experiments. This work establishes a basis for an incremental model development strategy based upon experiments, modeling, and comparative analysis to establish model parameters that could predict the slip processes that lead to damage evolution in lead-free solder joints.

  2. 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 area of local high trench-parallel gravity anomaly (TPGA), suggesting the presence of subducting seamounts that promote high-frequency generation. Our results highlight the complexity of the interactions between large-scale aseismic slow-slip and dynamic ruptures of megathrust earthquakes.

  3. The Slumgullion Natural Laboratory for Observing Slip Phenomena

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  4. Insights to slip behavior on rough faults using discrete element modeling

    NASA Astrophysics Data System (ADS)

    Fournier, Thomas; Morgan, Julia

    2012-06-01

    We simulate a range of fault slip behaviors using the discrete element method (DEM) to examine the controls on different slip modes on rough faults. Shear strain is imposed upon a 2-D bonded particle assemblage that contains a predefined fault. Slip modes on the fault vary from creep, to slow-slip, to stick-slip behavior, both spatially and temporally. The mode of slip is controlled largely by the local stress field along the fault, which depends on the local fault roughness. Portions of the fault that fail in relatively low normal stress regimes tend to slide continuously, whereas areas with high clamping stress produce stick-slip events. During stick-slip events, regions within the rupture zone that experience high slip are associated with physical asperities on the fault; ruptures terminate at barriers and through dissipation of the stored elastic energy. The simulated events show stress drops between 0.2-50 MPa, a slightly larger range than is inferred for natural earthquakes. Simulated events also have higher slip magnitudes than are observed during earthquakes for a given rupture length. The simulation produces many characteristics of fault behavior and is shown to be a successful avenue for future studies on the mechanics of fault slip.

  5. Stress fluctuations and macroscopic stick-slip in granular materials.

    PubMed

    Evesque, P; Adjémian, F

    2002-11-01

    This paper deals with the quasi-static regime of deformation of granular matter. It investigates the size of the Representative Elementary Volume (REV), which is the minimum packing size above which the macroscopic mechanical behaviour of granular materials can be defined from averaging. The first part uses typical results from recent literature and finds that the minimum REV contains in general 10 grains; this result holds true either for most experiments or for Discrete Element Method (DEM) simulation. This appears to be quite small. However, the second part gives a counterexample, which has been found when investigating uniaxial compression of glass spheres which exhibit stick-slip; we show in this case that the minimum REV becomes 10(7) grains. This makes the system not computable by DEM. Moreover, similarity between the Richter law of seism and the exponential statistics of stick-slip is stressed. PMID:15010916

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

    E-print Network

    Wolff, K; Cates, M E

    2012-01-01

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

  7. Determination of stress from slip data: Faults and folds

    NASA Astrophysics Data System (ADS)

    Michael, Andrew J.

    1984-12-01

    A new technique is derived to invert slickenside data for the stress field that caused the faulting episode. This inversion is simplified by the assumption that the magnitude of the tangential traction on the various fault planes, at the time of rupture, is similar. Study of three normal faulting regimes shows that the inversion derived with this assumption yields results that closely match older inversions that did not include the assumption. Hence the assumption may be valid and is shown to be justified by analyzing a simple fracture criterion. Application of slip data inversions is extended from faulting regimes to the slip on bedding plane faults in folding regimes. Comparison of the inversion results with the geometry of the folds shows this application to be successful, greatly increasing the number of data sets that can be used to find the paleostress field.

  8. Competition between shear banding and wall slip in wormlike micelles

    E-print Network

    Paul Lettinga; Sébastien Manneville

    2009-11-24

    The interplay between shear band (SB) formation and boundary conditions (BC) is investigated in wormlike micellar systems (CPyCl--NaSal) using ultrasonic velocimetry coupled to standard rheology in Couette geometry. Time-resolved velocity profiles are recorded during transient strain-controlled experiments in smooth and sand-blasted geometries. For stick BC standard SB is observed, although depending on the degree of micellar entanglement temporal fluctuations are reported in the highly sheared band. For slip BC wall slip occurs only for shear rates larger than the start of the stress plateau. At low entanglement, SB formation is shifted by a constant $\\Delta\\dot{\\gamma}$, while for more entangled systems SB constantly "nucleate and melt." Micellar orientation gradients at the walls may account for these original features.

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

    E-print Network

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

    2012-02-29

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

  10. Flexural-slip folding in the Meguma Group, Nova Scotia, Canada

    NASA Astrophysics Data System (ADS)

    Horne, Richard; Culshaw, Nicholas

    2001-10-01

    Flexural-slip folding has been established for two anticlines in the Meguma Group, Nova Scotia. Flexural slip postdates the main Acadian episode of flexural-flow fold growth and represents a late, brittle-ductile reactivation of the fold belt. Flexural-slip structures are dominated by bedding-parallel movement horizons, but include a linked system of frontal and lateral ramps and conjugate movement horizons. Slip amount calculated from displacement of discordant quartz veins, combined with vein spacing, indicates an average local shear strain of approximately 0.5. However, because flexural-slip occurred when the fold limbs were steep, the shear strain accounts for a small change in limb dip (4-8°). Variation of slip amount with spacing of movement horizons suggests progressive flexural slip was accommodated by continuous initiation of new movement horizons as well as continuing slip on existing movement horizons. The presence of quartz veins along flexural-slip structures together with evidence for ductile deformation coeval with flexural slip suggests that slip episodes were fluid assisted and intermittent, separated by periods of ductile deformation and build up of fluid pressure. Flexural-slip veins in the Ovens Anticline are auriferous and a flexural slip model may be appropriate for other similar Meguma gold deposits. Thrust sheets, up to 10 m thick, occurring on a fold limb are interpreted to have originated in flat box fold hinges and to have been placed onto the steep limbs of the chevron folds during the flexural slip episode. Thrusting may have assisted the transformation of a box fold into a chevron.

  11. Nonlinear dynamical triggering of slow slip on simulated earthquake faults with implications to Earth

    NASA Astrophysics Data System (ADS)

    Johnson, P. A.; Carpenter, B.; Knuth, M.; Kaproth, B. M.; Le Bas, P.-Y.; Daub, E. G.; Marone, C.

    2012-04-01

    Among the most fascinating, recent discoveries in seismology are the phenomena of dynamically triggered fault slip, including earthquakes, tremor, slow and silent slip—during which little seismic energy is radiated—and low frequency earthquakes. Dynamic triggering refers to the initiation of fault slip by a transient deformation perturbation, most often in the form of passing seismic waves. Determining the frictional constitutive laws and the physical mechanism(s) governing triggered faulting is extremely challenging because slip nucleation depths for tectonic faults cannot be probed directly. Of the spectrum of slip behaviors, triggered slow slip is particularly difficult to characterize due to the absence of significant seismic radiation, implying mechanical conditions different from triggered earthquakes. Slow slip is often accompanied by nonvolcanic tremor in close spatial and temporal proximity. The causal relationship between them has implications for the properties and physics governing the fault slip behavior. We are characterizing the physical controls of triggered slow slip via laboratory experiments using sheared granular media to simulate fault gouge. Granular rock and glass beads are sheared under constant normal stress, while subjected to transient stress perturbation by acoustic waves. Here we describe experiments with glass beads, showing that slow and silent slip can be dynamically triggered on laboratory faults by ultrasonic waves. The laboratory triggering may take place during stable sliding (constant friction and slip velocity) and/or early in the slip cycle, during unstable sliding (stick-slip). Experimental evidence indicates that the nonlinear-dynamical response of the gouge material is responsible for the triggered slow slip.

  12. Comparison of Geodetic and Late Pleistocene Slip Rates for the Southern Dead Sea Fault System

    NASA Astrophysics Data System (ADS)

    Cochran, W. J.; Gomez, F.; Abu Rajab, J. S.; Al-Tarazi, E.

    2012-12-01

    Comparisons of short-term (geodetic) and Late Quaternary slip rates have been used to assess time-variable fault kinematics along various active faults, globally. Differences between such types slip rates may have implications for crustal rheology and/or temporal variations in plate motion. This research aims to compare the geodetically-derived slip rates with slip rates based on Late Pleistocene landforms along the southern Dead Sea fault system (DSFS). The DSFS is an active, left-lateral transform that accommodates differential movement between the Arabian and Sinai plates. A number of slip rates have been previously reported ranging from 2 to 6mm/yr. However, comparison of various slip rates requires ensuring that associated uncertainties are assessed using a standard. New GPS velocities from Jordan are combined with other available GPS data, and are used to model slip rates using elastic block models. Resulting slip rates are 4.3 to 5.3 mm/yr with fault locking depths of 8 - 15 km. Late Pleistocene rates are assessed from published observations, as well as new data. New mapping of offset alluvial fans in the southern Wadi Araba was facilitated by multi-spectral imagery and high-resolution digital elevation model. These fans correlate with regional aggradation events, with the resulting Late Pleistocene slip rates ranging from 4.2 to 5.1 mm/yr. Statistically, the geodetic and neotectonic slip rates are identical. Additionally, a 3-dimensional slip vector for the last earthquake in the northern Wadi Araba is constructed using close-range photogrammetry of a faulted Byzantine aqueduct that indicates both horizontal and vertical displacements. Previous studies suggested characteristic earthquake slip, so slip rates and this slip vector provide a means of assessing mean EQ recurrence interval, as well as the role of earthquakes in constructing the long-term topography along this part of the transform.

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

    PubMed Central

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

    2015-01-01

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

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

    DOEpatents

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

    1991-01-01

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

  15. Rupture process of 2011 Mw7.1 Van, Eastern Turkey earthquake from joint inversion of strong-motion, high-rate GPS, teleseismic, and GPS data

    NASA Astrophysics Data System (ADS)

    Konca, A. Ozgun

    2015-10-01

    We analyzed the rupture process of the 2011 Mw7.1 Van, Eastern Turkey earthquake using teleseismic, strong-motion, 1-Hz GPS waveforms and static GPS displacement measurements. We performed data sensitivity analyses using four different rupture scenarios. Overall, when geodetic and seismic datasets are modeled jointly, slip distribution is well-constrained and rupture velocity can be obtained. The 2011 Van earthquake is a case where none of the available datasets are sufficient to constrain the slip distribution and the rupture kinematics on their own. This study confirms that rather than fitting one dataset perfectly, using multiple datasets jointly leads to a better-constrained slip distribution. The kinematic model obtained from the joint inversion of all the available data shows a 45-km-long bilateral rupture with two sub-events; one larger slip patch propagating up-dip and toward west of the hypocenter and a smaller second slip patch toward the east. The highest slip is to the west of the hypocenter with a peak value of 4.5 m. The slip is confined to the depths of 7.5 to 20 km and the shallower part of the fault remains unbroken. The average rupture velocity is around 3 km/s, close the Rayleigh wave velocity. The rupture is faster with shorter rise times for the larger sub-event toward the west, while the rise times are longer for the smaller sub-event to the east. This difference in seismic behavior might be related to the segmentation of the fault.

  16. 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.

  17. Joint Newspaper Operating Agreements.

    ERIC Educational Resources Information Center

    Parsons, Marie

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

  18. 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 ...

  19. Stick-slip advance of the Kohat Plateau in Pakistan

    NASA Astrophysics Data System (ADS)

    Satyabala, S. P.; Yang, Zhaohui; Bilham, Roger

    2012-02-01

    Throughout most of the Himalaya, slip of the Indian Plate is restrained by friction on the interface between the plate and the overlying wedge of Himalayan rocks. Every few hundred years, this interface--or décollement--ruptures in one or more Mw >=8 earthquakes. In contrast, in the westernmost Himalaya, the Indian Plate slips aseismically beneath wide plateaux fronting the Kohistan Mountains. The plateaux are underlain by viscous décollements that are unable to sustain large earthquakes. Potwar, the widest of these plateaux is underlain by viscous salt, which currently permits it to slide at rates of about 3mmyr-1 (refs , ), much slower than its 2 Myr average. This deceleration has been attributed to recently increased friction through the loss of salt from its décollement. Here we use interferometric synthetic aperture radar and seismic data to assess movement of the Kohat Plateau--the narrowest and thickest plateau. We find that in 1992 an 80 km2 patch of the décollement ruptured in a rare Mw 6.0 earthquake, suggesting that parts of the décollement are locally grounded. We conclude that this hybrid seismic and aseismic behaviour represents an evolution of the mode of slip of the plateaux from steady creep towards increasingly widespread seismic rupture.

  20. Velocity dependence of serpentinite friction promotes aseismic slip on faults

    SciTech Connect

    Reinen, L.A.; Weeks, J.D.; Tullis, T.E. . Dept. of Geological Sciences)

    1992-01-01

    Serpentinite is common on many crustal faults and it has been suggested that the presence of serpentine on these faults may promote aseismic slip. Consequently, the authors have experimentally measured the frictional constitutive response of both antigorite and lizardite polymorphs of serpentine to step changes in velocity. This was done at room temperature in rotary direct shear; normal stress was 25 MPa, and velocities ranged from 32 mm/yr to 3.2 [times] 10[sup 5] mm/yr. The frictional behavior of both serpentine polymorphs indicates that the presence of either one on a fault would result in aseismic creep in the shallow crust at typical plate motion rates. In contrast to other rock types, such as granite, both serpentinites display velocity-strengthening behavior at slow sliding velocities: below some transitional velocity, the frictional resistance increases with velocity, thus promoting stable aseismic slip. At faster velocities, however, frictional strength has a negative dependence on velocity (velocity weakening), which provides the potential for unstable sliding, leading to earthquakes. The coefficient of friction of the antigorite serpentinite is similar to that of other silicates, while that of the lizardite is much lower. The low frictional strength of lizardite may help explain some geologic observations that serpentine appears quite mobile during deformation in the crust. However, it is the velocity-strengthening behavior observed in both serpentinites at low sliding velocities, and not the frictional strength, that will promote aseismic slip on serpentine-bearing faults at typical rates of plate motion.

  1. Test results of simulated satellite slip ring experiments

    NASA Astrophysics Data System (ADS)

    Martin, R. W.

    Experimental data pertaining to the long-term study of satellite data transmission slip ring noise generating phenomena is reported. Detailed test data from a 7,700-hour and an 8,100-hour experiment are included. Both average value and instantaneous data are presented of ring/brush electrical contact resistance, ring/brush micromotions and ring/brush frictional forces. Interrelationships among these parameters are examined in an effort to understand the mechanisms of performance degradation. Results will be utilized to indicate further areas of experimentation which may lead to the improvement of data transmission slip ring performance. Suggestions are made for possible techniques to lower data transmission error rates through satellite slip rings. A microprocessor, which provides monitor and control capability, allows unattended operation as well as selective data acquisition through a set of variable parameter acceptance limits. Modifications and additions to the microprocessor software and data acquisition system, originally presented at the 26th International Instrumentation Symposium, are also reported.

  2. Rapid slip of the Gyaring Co fault in Central Tibet

    NASA Astrophysics Data System (ADS)

    Chung, Lingho; Chen, Yue-Gau; Cao, Zhongquan; Yin, Gongming; Kunz, Alexander; Fan, Anchuan; Wu, Tzu-Shuan; Xu, XiWei

    2015-04-01

    The Gyaring Co fault (GCF) is one of a series of active en echelon faults of the Karakoram-Jiali fault zone (KJFZ) in the Central Tibetan Plateau. It has been reported as a dextral fault, striking N50°-60°W at a rate of ca. 10 to 20 mm/yr (Armijo et al. 1989). Another en echelon fault, Beng Co fault (BCF), was located on the 1951 M8 event also implies the possibility of earthquake hazard at GCF. By interpreting high resolution satellite imageries, we are able to remap ~140 fault traces along the GCF. Combining optically stimulated luminescence (OSL) ages with the offset obtained from satellite imagery analysis and field survey, the slip rate along the GCF can be estimated as 12-17 mm/yr since ca. 80 ka. This study also focuses on a section of the western segment of the GCF, where the slip has been recognized to have occurred at 3.0 ± 1.6 m more than 7 times. This ~3 m slip implies MW 7.2-7.4 earthquakes recurring to the western segment in every 200 yrs, while reaching about MW 7.7 if both segments could break at the same time.

  3. Spiralling tapered slip-on drill string stabilizer

    SciTech Connect

    Beasley, T.R.; Teng, C.C.

    1986-12-23

    A stabilizer is described for use in a drilling string comprising: a substantially cylindrical body member having a central passageway to accommodate the drill sting, the inside surface of the body member defining a right-hand spiralling thread with a tapered trailing edge which spirals from a starting point on the body member. The thread terminates internally of the body member in an arcuate recess extending around the interior of the body member; a key member is secured to the inner wall surface of the recess of the body member, the key member having a lug extending longitudinally of the body member within the recess; a slip member adapted to thread within the body member between the body member and the drill string. The slip defines a right-hand thread with a matching tapered trailing edge configured to make up with the right-hand thread on the body member and to wedge between the body member and the drill string. One end of the slip terminates in a longitudinally disposed shoulder capable of abutting the lug upon threading of the clip within the body member.

  4. Geometrical and mechanical factors that influence slipped capital femoral epiphysis: a finite element study.

    PubMed

    Castro-Abril, Hector A; Galván, Fernando; Garzón-Alvarado, Diego A

    2015-09-01

    Slipped capital femoral epiphysis (SCFE) is an orthopedic pathology in which damage of the growth plate leads to the anterosuperior displacement of the femoral body in respect to the femoral head. Despite being a widely studied disease, its etiology is still unknown. This study was carried out to determine the influence of the physeal-diaphysis angle, body mass, the presence of the perichondrial ring, the type of physical activity, and physeal thickness on SCFE. For this purpose, a finite element analysis of the hip joint and the femur-physis interface was carried out. With the computational model, the Von Mises stresses along the growth plate were calculated and subsequently analyzed statistically to find their correlation with the studied factors. It was found that body mass, the type of physical activity, and the presence of the perichondrial ring had more statistical relevance for the physeal stresses than the physeal-diaphysis angle and the physeal thickness. Thus, our work suggests that changes in growth plate inclination and thickness do not influence the etiology of SCFE. PMID:26062006

  5. 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 ...

  6. The coseismic deformation and fault slip distribution of the Mw9.0 Tohoku-Oki earthquake estimated from GPS and InSAR

    NASA Astrophysics Data System (ADS)

    Feng, G. C.; Jónsson, S.; Ding, X. L.; Li, Z.

    2012-04-01

    The magnitude Mw9.0 Tohoku-Oki earthquake occurred on 11 March 2011 off the Pacific coast of Tohoku district in eastern Japan. It is the largest earthquake in the recent history of Japan and the fourth largest earthquake to occur in the world since 1900. Utilizing different geophysical datasets, e.g. teleseismic, strong motion, geodetic observations and tsunami datasets, several coseismic slip distribution models have already be published. However, while InSAR is another important data source, it has mostly been excluded in studies of the fault slip distribution of this earthquake. In addition, the earthquake provides an excellent opportunity to study fault-slip resolution obtained by different measurement methods, as the Japanese islands are extensively instrumented with both seismic and GPS instruments. In this study, we map the coseismic deformation of the Tohoku-Oki earthquake with InSAR by using data from three descending Envisat tracks and six ascending ALOS tracks that cover most of northeastern Japan. Due to the inaccurate satellite-orbit information, the coseismic interferograms contain phase ramps, which have resulted in inconsistency between the deformation maps released by different research groups. We removed these ramps in the InSAR data by using a 2-D quadratic phase model based on GPS measurements provided by the ARIA team at JPL and Caltech. The average RMS between the InSAR and GPS measurements decreased from 17.8 cm to 7.7 cm after the orbital ramp correction, indicating significant improvements to the InSAR data by this procedure. The calibrated coseismic deformation InSAR measurements show a maximum line of sight (LOS) displacement of up to 3.7 m in the ascending ALOS data and 2.4 m in the descending Envisat data. Using onland and offshore GPS data, as well as the InSAR data, we generated 5 solutions based on 5 different combinations of the data: (a) GPS data, (b) InSAR data without GPS calibrations, (c) GPS-calibrated InSAR data, (d) GPS and InSAR data, and (e) GPS and InSAR data, but without offshore GPS data. Based on comparisons between the resulting 5 fault-slip models, we find that the GPS-only model (based on dataset (a)) is almost identical to the joint model (dataset (d)), regarding slip magnitude, pattern, and rake. This means that little is gained by including the InSAR observations in the fault slip modeling in this case. However, we also find that the main pattern of fault slip can be determined by the InSAR observations alone, by simultaneously estimating long wavelength orbital and atmosphere delay errors in the data. Our final preferred solution includes both reverse faulting and strike slip. The maximum reverse and strike slip values are 36.0 m and 6.0 m, respectively, at a depth of 6 km northeast of the epicenter. The total geodetic moment is 3.6×1022 Nm (Mw 9.01), similar to seismological estimates. Keywords: Tohoku-Oki earthquake; coseismic deformation; InSAR; orbital ramps correction; Slip distribution

  7. Latest Pleistocene and Holocene slip rates on the Lone Mountain fault: Evidence for accelerating slip in the Silver Peak-Lone Mountain extensional complex

    NASA Astrophysics Data System (ADS)

    Lifton, Zachery M.; Frankel, Kurt L.; Newman, Andrew V.

    2015-03-01

    Determining the constancy of fault slip rates over time is critical in characterizing strain distribution across plate boundaries such as the Pacific-North American plate boundary in the western U.S. We present results from the Lone Mountain fault, a normal fault within the southern Walker Lane, that suggest slip rates there may have increased approximately twofold since the late Pleistocene. We combine detailed field surficial mapping, topographic surveying, and 10Be cosmogenic nuclide exposure ages to calculate new late Pleistocene and Holocene slip rates on the Lone Mountain fault. Alluvial fans with ages of 14.6 ± 1.4 ka and 8.0 ± 0.9 ka are vertically offset 10.2 ± 0.6 m and 4.7 ± 0.6 m, respectively, yielding vertical slip rates of 0.7 ± 0.1 mm/yr and 0.6 ± 0.1 mm/yr. These slip rates are faster than the rates of 0.1 to 0.4 mm/yr from earlier in the Pleistocene, defining a pattern of accelerating slip on the Lone Mountain fault over a timescale of 104 years. The possibility of accelerating slip rates in parts of the Walker Lane partially reconciles the observed discrepancy between long- and short-term slip rates in this region and elucidates the distribution of strain across an evolving plate boundary.

  8. Structural and biochemical studies of SLIP1–SLBP identify DBP5 and eIF3g as SLIP1-binding proteins

    PubMed Central

    von Moeller, Holger; Lerner, Rachel; Ricciardi, Adele; Basquin, Claire; Marzluff, William F.; Conti, Elena

    2013-01-01

    In metazoans, replication-dependent histone mRNAs end in a stem-loop structure instead of the poly(A) tail characteristic of all other mature mRNAs. This specialized 3? end is bound by stem-loop binding protein (SLBP), a protein that participates in the nuclear export and translation of histone mRNAs. The translational activity of SLBP is mediated by interaction with SLIP1, a middle domain of initiation factor 4G (MIF4G)-like protein that connects to translation initiation. We determined the 2.5 Å resolution crystal structure of zebrafish SLIP1 bound to the translation–activation domain of SLBP and identified the determinants of the recognition. We discovered a SLIP1-binding motif (SBM) in two additional proteins: the translation initiation factor eIF3g and the mRNA-export factor DBP5. We confirmed the binding of SLIP1 to DBP5 and eIF3g by pull-down assays and determined the 3.25 Å resolution structure of SLIP1 bound to the DBP5 SBM. The SBM-binding and homodimerization residues of SLIP1 are conserved in the MIF4G domain of CBP80/20-dependent translation initiation factor (CTIF). The results suggest how the SLIP1 homodimer or a SLIP1–CTIF heterodimer can function as platforms to bridge SLBP with SBM-containing proteins involved in different steps of mRNA metabolism. PMID:23804756

  9. Improved ceramic slip casting technique. [application to aircraft model fabrication

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (inventor); Vasquez, Peter (inventor)

    1993-01-01

    A primary concern in modern fluid dynamics research is the experimental verification of computational aerothermodynamic codes. This research requires high precision and detail in the test model employed. Ceramic materials are used for these models because of their low heat conductivity and their survivability at high temperatures. To fabricate such models, slip casting techniques were developed to provide net-form, precision casting capability for high-purity ceramic materials in aqueous solutions. In previous slip casting techniques, block, or flask molds made of plaster-of-paris were used to draw liquid from the slip material. Upon setting, parts were removed from the flask mold and cured in a kiln at high temperatures. Casting detail was usually limited with this technique -- detailed parts were frequently damaged upon separation from the flask mold, as the molded parts are extremely delicate in the uncured state, and the flask mold is inflexible. Ceramic surfaces were also marred by 'parting lines' caused by mold separation. This adversely affected the aerodynamic surface quality of the model as well. (Parting lines are invariably necessary on or near the leading edges of wings, nosetips, and fins for mold separation. These areas are also critical for flow boundary layer control.) Parting agents used in the casting process also affected surface quality. These agents eventually soaked into the mold, the model, or flaked off when releasing the case model. Different materials were tried, such as oils, paraffin, and even an algae. The algae released best, but some of it remained on the model and imparted an uneven texture and discoloration on the model surface when cured. According to the present invention, a wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell mold of the calcium sulfate-bonded investment material. The shell mold is cooled to room temperature, and a ceramic slip is poured therein. After a ceramic shell of desired thickness has set up in the shell mold, excess ceramic slip is poured out. While still wet, the shell mold is peeled from the ceramic shell to expose any delicate or detailed parts, after which the ceramic shell is cured to provide a complete, detailed, precision ceramic article without parting lines.

  10. Excitation of energy harvesters using stick-slip motion

    NASA Astrophysics Data System (ADS)

    Helseth, L. E.

    2014-08-01

    During the past decades a large number of energy harvesting systems with the ability to transform mechanical energy into electrical energy have been proposed, ranging from systems exhibiting pure sinusoidal motion to stochastic systems. However, to date little emphasis has been put on stick-slip motion as a method for excitation of energy harvesting systems. Stick-slip motion can be associated with both microscopic and macroscopic processes and is omnipresent. The motion can be characterized by two stages. In the first stage there is buildup of elastic energy with little associated motion, whereas in the second stage the elastic energy is released into kinetic energy. We study here the spectral signal characteristics of two different electrical generators excited by stick-slip motion: a piezoelectric macro fiber composite and a triboelectric generator. The force and the voltage generated during the motion were monitored, and we found that the signal spectral density of both variables changes with the frequency in a characteristic manner, thus classifying the slip-stick motion as a colored noise excitation scheme. The force spectral density in both systems was found to exhibit a power-law spectrum following an {{f}^{-2}} trend, where f is the frequency. The voltage spectral density was governed by the product of a high-pass filter, the force spectral density, and the intrinsic generator spectral density. Here the piezoelectric generator exhibited a nearly flat voltage spectral density below the cutoff frequency of the high-pass filter and an {{f}^{-2}} spectrum at higher frequencies, thus demonstrating that the piezoelectric coupling coefficient had a nearly flat frequency response. On the other hand, the triboelectric generator had a coupling coefficient with a spectral response that varied in a non-systematic manner, possibly related to the large number of contact sites and relaxation times occurring during operation. The average power delivered by the generators to a resistive load was also measured for sinusoidal mechanical excitations and was compared with the average power generated by stick-slip motion.

  11. The Relationship Between Coseismic Slip and Postseismic Creep

    NASA Astrophysics Data System (ADS)

    Hussain, E.; Wright, T. J.; Houseman, G. A.; Walters, R. J.; Hooper, A. J.; Bekaert, D. P.

    2014-12-01

    Shallow aseismic creep has been observed on many strike-slip faults around the world. The initiation process for shallow creep remains unclear, and no clear explanation exists for why creep persists for years/decades after some earthquakes while after others it decays completely within months. Many earthquakes exhibit a shallow coseismic slip deficit. We hypothesise that shallow creep can begin after such events to 'catch up' with the slip deficit relative to deeper sections of the fault. We test this hypothesis with persistent scatterer InSAR analysis of 3 descending and 2 ascending Envisat tracks that together span a region covering the 1999 Izmit and Duzce ruptures in Turkey. Our data covers an 8 year time window between 2003 - 2010. A section of the Izmit rupture was previously shown to be undergoing shallow creep. But the spatial and temporal nature of this creep remains unclear. We use a small baseline processing strategy using the StaMPS software, which allows for checking of unwrapping errors by summing the residuals around closed interferometric loops. We make an addition to the code to detect and fix unwrapping errors. This is done by automatically detecting and fixing pixels that are unwrapped correctly in an initial run. The procedure is iterated until unwrapping errors are corrected. By combining our InSAR results with existing GPS measurements we obtained a map of horizontal and vertical surface displacements over time. From this we calculated the variation in creep rates along the earthquake ruptures. We show that shallow creep at an average rate of 10 mm/yr is limited to the Izmit rupture and does not extend laterally to the Duzce segment. We use elastic dislocation models to determine the creep distribution with depth and compare with the coseismic slip observed in the Izmit earthquake. We find the creep rate is highest in a region of shallow coseismic slip deficit. The creep rate exponentially decays with time after the earthquake to a steady rate. We model this temporal behaviour using rate and state friction theory and determine variations in frictional properties within the creeping region.

  12. Development of microsized slip sensors using dielectric elastomer for incipient slippage

    NASA Astrophysics Data System (ADS)

    Hwang, Do-Yeon; Kim, Baek-chul; Cho, Han-Jeong; Li, Zhengyuan; Lee, Youngkwan; Nam, Jae-Do; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, J. C.

    2014-04-01

    A humanoid robot hand has received significant attention in various fields of study. In terms of dexterous robot hand, slip detecting tactile sensor is essential to grasping objects safely. Moreover, slip sensor is useful in robotics and prosthetics to improve precise control during manipulation tasks. In this paper, sensor based-human biomimetic structure is fabricated. We reported a resistance tactile sensor that enables to detect a slip on the surface of sensor structure. The resistance slip sensor that the novel developed uses acrylonitrile-butadiene rubber (NBR) as a dielectric substrate and carbon particle as an electrode material. The presented sensor device in this paper has fingerprint-like structures that are similar with the role of the human's finger print. It is possible to measure the slip as the structure of sensor makes a deformation and it changes the resistance through forming a new conductive route. 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 was successfully detected. In this paper, we will discuss the slip detection properties so four sensor and detection principle.

  13. Stick-slip motion of an Antarctic Ice Stream: The effects of viscoelasticity

    NASA Astrophysics Data System (ADS)

    Goldberg, D. N.; Schoof, C.; Sergienko, O. V.

    2014-07-01

    Stick-slip behavior is a distinguishing characteristic of the flow of Whillans Ice Stream (Siple Coast, Antarctica). Distinct from stick slip on Northern Hemisphere glaciers, which is generally attributed to supraglacial melt, the behavior is thought be controlled by basal processes and by tidally induced stress. However, the connection between stick-slip behavior and flow of the ice stream on long time scales, if any, is not clear. To address this question we develop a new ice flow model capable of reproducing stick-slip cycles similar to ones observed on the Whillans Ice Plain. The model treats ice as a viscoelastic material and emulates the weakening and healing that are suggested to take place at the ice-till interface. The model results suggest the long-term ice stream flow that controls ice discharge to surrounding oceans is somewhat insensitive to certain aspects of stick-slip behavior, such as velocity magnitude during the slip phase and factors that regulate it (e.g., elastic modulus). Furthermore, it is found that factors controlling purely viscous flow, such as temperature, influence stick-slip contribution to long-term flow in much the same way. Additionally, we show that viscous ice deformation, traditionally disregarded in analysis of stick-slip behavior, has a strong effect on the timing of slip events and therefore should not be ignored in efforts to deduce bed properties from stick-slip observations.

  14. A theoretical study of induced-charge dipolophoresis of ideally polarizable asymmetrically slipping Janus particles

    NASA Astrophysics Data System (ADS)

    Boymelgreen, Alicia M.; Miloh, Touvia

    2011-07-01

    We consider the non linear electrophoretic transport of uncharged, ideally polarizable hydrodynamic Janus spheres, the inhomogeneity of which is produced by a variable Navier slip condition at the particle surface. A general, three dimensional formulation enabling calculation of the electrophoretic mobility of any patchy particle, with an arbitrary tensorial slip boundary condition is provided. The solution avoids the common assumption of an infinitely thin electric double layer (?) and Navier slip coefficient (b) and is thereby valid for finite values of these parameters, which is of particular importance at the nanoscale. The specific case of a Janus sphere, consisting of two equal hemispheres, each with a different but constant slip boundary condition is solved semi-analytically and numerically. In the instance where the slip coefficients at each hemisphere are equal, induced charge electro-osmotic flow is evident at an increased rate as compared to a homogeneous sphere with no slip. If the slip coefficients differ from each other, the particle is found to self-align with the electric field and travel with the slip surface facing forward. The increased pumping rates and mobility found in the cases of the homogeneous and Janus spheres respectively, occur as a function of the ratio b/b? ? and are most significant for the combination of a thin electric double layer (EDL) and large slip length. However, it is also illustrated that the size of the EDL independently dominates the effects of slip.

  15. Jet impingement and the hydraulic jump on horizontal surfaces with anisotropic slip

    NASA Astrophysics Data System (ADS)

    Prince, Joseph F.; Maynes, Daniel; Crockett, Julie

    2014-04-01

    This paper presents an analysis that describes the dynamics of laminar liquid jet impingement on horizontal surfaces with anisotropic slip. Due to slip at the surface and the anisotropy of its magnitude, the overall behavior departs notably from classical results. For the scenario considered the slip length varies as a function of the azimuthal coordinate and describes superhydrophobic surfaces micropatterned with alternating ribs and cavities. The thin film dynamics are modeled by a radial momentum analysis for a given jet Reynolds number and specified slip length and the influence of slip on the entire flow field is significant. In an average sense the thin film dynamics exhibit similarities to behavior that exists for a surface with isotropic slip. However, there are also important deviations that are a direct result of the azimuthally varying slip and these become more pronounced at higher Reynolds numbers and at greater slip lengths. The analysis also allows determination of the azimuthally varying radial location of the hydraulic jump that forms due to an imposed downstream depth. Departure from the no slip case and from the scenario of isotropic slip is characterized over a range of jet Reynolds numbers and realistic slip length values. The results show that for all cases the hydraulic jump is elliptical, with eccentricity increasing as the Reynolds number or slip length increases, or as the downstream depth decreases. The radial location of the hydraulic jump is greatest in the direction of greatest slip (parallel to the microribs), while it is a minimum in the direction transverse to the rib/cavity structures. The model results for the hydraulic jump radial position are compared to experimental measurements with good agreement.

  16. Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere Earth models

    SciTech Connect

    Savage, J.C. )

    1990-04-10

    By virtue of the images used in the dislocation solution, the deformation at the free surface produced throughout the earthquake cycle by slippage on a long strike-slip fault in an Earth model consisting of an elastic plate (lithosphere) overlying a visoelastic half-space (asthenosphere) can be duplicated by prescribed slip on a vertical fault embedded in an elastic half-space. For the case in which each earthquake ruptures the entire lithosphere (thickness H), the half-space equivalent slip rate is as follows: Depth interval 0-H, slip identical to that in lithosphere-asthenosphere model (i.e., abrupt coseismic slip and no subsequent slip); depth interval (2n {minus} 1) H to (2n + 1) H (n = 1,2,...), slip rate uniform in space and dependent upon time as F{sub n}(t) exp ({minus}t/{tau}) where F{sub n} is a (n {minus} 1) degree polynomial in t, {tau} is twice the asthenosphere relaxation time, and t is measured from the instant after the preceding earthquake. The slip rate averaged over the seismic cycle in each depth interval equals the secular rate of relative plate motion. The surface deformation due to the earthquake cycle in the lithosphere-asthenosphere model can be calculated very simply from the half-space model with time-dependent slip in the two depth intervals H-3H and 3H-5H, and uniform slip at a rate equal to the secular relative plate velocity below depth 5H. Inversion of 1973-1988 geodetic measurements of deformation across the segment of the San Andrea fault in the Transverse Ranges north of Los Angeles for the half-space equivalent slip distribution suggests no significant slip on the fault above 30 km and a uniform slip rate of 36 mm/yr below 30 km.

  17. 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.

  18. 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.

  19. Determining the causes of fault slip rate variability for Northern Apennine thrusts on intermediate timescales

    NASA Astrophysics Data System (ADS)

    Gunderson, K. L.; Anastasio, D. J.; Pazzaglia, F. J.

    2012-12-01

    Documenting fault slip rate variability on intermediate (10^4-10^5 yr) timescales is crucial for understanding the process-linkages of short-term (10^1-10^3 yr) and long-term (10^6 yr) patterns of deformation; however, the lack of long records of fault slip with 10^4-10^5 yr resolution presents a major barrier to understanding the underlying process responsible for slip rate variability at those timescales. Taking advantage of spectacular, continuous exposure of growth strata, we document 10^4-10^5 yr resolution records of unsteady fault slip for the past 3.0 myr for three unconnected, shallow blind thrust anticlines growing along the Northern Apennine mountain front, Italy. Fault slip rates for these thrusts were determined from progressive restorations of marine and continental growth strata deposited on the anticlinal limbs. These restorations were supported by subsurface corre-lations of the measured growth sections in order to constrain the fold geometries and kin-ematics. Magnetostratigraphy, cyclostratigraphy, cosmogenic radionuclide (CRN) burial dating, and optically stimulated luminescence (OSL) burial dating provided the high-resolution age models for the growth sections. Slip histories determined from our pro-gressive restorations indicate that all three of the thrust faults exhibited high-frequency slip rate variability. This variability is typically manifest by longer periods of decelerated fault slip punctuated by shorter periods of accelerated fault slip, typically lasting between 80-200 kyr. During times when slip rates were slow, growth strata geometries show ac-celerated slip was accommodated by more foreland structures, suggesting slip partitioning at 10^4-10^5 yr timescales. This high frequency variability is superimposed on a low frequency slip rate variability manifest by an overall deceleration in slip on the shallow thrusts since 3.0 myr. Major decelerations in slip rates were coincident with the activation of thick-skinned thrusting in the Apennines, representing a dynamic reorganization of the Apennine wedge. This suggests two separate causes for slip rate variability on Apennines thrusts: a high-frequency variability that is likely due to processes internal to the wedge, such as slip partitioning, and a low frequency variability that is probably caused by exter-nal forces affecting the entire Apennine wedge.

  20. Just How Joint Is Joint Action in Infancy? Malinda Carpenter

    E-print Network

    Carpenter, M.alinda

    Just How Joint Is Joint Action in Infancy? Malinda Carpenter Department of Developmental 2008; received in revised form 19 December 2008; accepted 20 January 2009 Abstract Joint action is central to countless aspects of human life. Here I examine the roots of joint action in infancy. First, I

  1. Joint Purchasing Consortium forms New Joint Procurement Committee

    E-print Network

    Victoria, University of

    Joint Purchasing Consortium forms New Joint Procurement Committee A new committee comprised of VPs the Consortium for a two year term. The Joint Procurement Committee members include: VP, Finance will be working on roles, responsibilities, and governance and implementation of the Wave 1 joint procurement

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

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

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

  3. Initiation time of near-infrared laser-induced slip on the surface of silicon wafers

    SciTech Connect

    Choi, Sungho; Jhang, Kyung-Young

    2014-06-23

    We have determined the initiation time of laser-induced slip on a silicon wafer surface subjected to a near-infrared continuous-wave laser by numerical simulations and experiments. First, numerical analysis was performed based on the heat transfer and thermoelasticity model to calculate the resolved shear stress and the temperature-dependent yield stress. Slip initiation time was predicted by finding the time at which the resolved shear stress reached the yield stress. Experimentally, the slip initiation time was measured by using a laser scattering technique that collects scattered light from the silicon wafer surface and detects strong scattering when the surface slip is initiated. The surface morphology of the silicon wafer surface after laser irradiation was also observed using an optical microscope to confirm the occurrence of slip. The measured slip initiation times agreed well with the numerical predictions.

  4. Method of reducing the green density of a slip cast article

    DOEpatents

    Mangels, John A. (Flat Rock, MI); Dickie, Ray A. (Birmingham, MI)

    1985-01-01

    The method disclosed in this specification is one of reducing the green density of an article cast in a slip casting operation. The article is cast from a casting slip containing silicon metal particles, yttrium containing particles, and a small amount of a fluoride salt which is effective to suppress flocculation of the silicon metal particles by y.sup.+3 ions derived from the yttrium containing particles. The method is characterized by the following step. A small amount of compound which produces a cation which will partly flocculate the particles of silicon metal is added to the casting slip. The small amount of this compound is added so that when the casting slip is slip cast into a casting mold, the partly flocculated particles of silicon will interrupt an otherwise orderly packing of the particles of silicon and particles of yttrium. In this manner, the green density of the slip cast article is reduced and the article may be more easily nitrided.

  5. Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip

    NASA Astrophysics Data System (ADS)

    Violay, M.; Di Toro, G.; Nielsen, S.; Spagnuolo, E.; Burg, J. P.

    2015-11-01

    Earthquakes occur because fault friction weakens with increasing slip and slip rates. Since the slipping zones of faults are often fluid-saturated, thermo-mechanical pressurization of pore fluids has been invoked as a mechanism responsible for frictional dynamic weakening, but experimental evidence is lacking. We performed friction experiments (normal stress 25 MPa, maximal slip-rate ?3 ms-1) on cohesive basalt and marble under (1) room-humidity and (2) immersed in liquid water (drained and undrained) conditions. In both rock types and independently of the presence of fluids, up to 80% of frictional weakening was measured in the first 5 cm of slip. Modest pressurization-related weakening appears only at later stages of slip. Thermo-mechanical pressurization weakening of cohesive rocks can be negligible during earthquakes due to the triggering of more efficient fault lubrication mechanisms (flash heating, frictional melting, etc.).

  6. Relation between surface slip topography and stress corrosion cracking in Ti-8 wt % Al

    NASA Technical Reports Server (NTRS)

    Boyd, J. D.; Hoagland, R. G.

    1974-01-01

    The deformation behavior of Ti-8 wt % Al has been investigated in an inert environment (air), and an aggressive environment (salt water). Details of surface slip geometry were examined by high resolution surface replicas at various stages of deformation in both environments. Specimens aged to contain a fine dispersion of Ti3Al precipitates failed by subcritical crack growth in salt water, whereas specimens in the single phase condition showed no effects of environment on the yield or fracture characteristics. The Ti3Al precipitates produce little change in strength level or slip character compared to the single phase alloy, and there is no evidence of any effects of environment on the character of surface slip. Rather, the presence of trenches along slip bands on the surface of aged specimens suggest that the specific effect of the Ti3Al precipitates is to render the surface slip steps chemically active relative to the surrounding matrix by slip induced dissolution of the particles.

  7. Knee joint replacement - discharge

    MedlinePLUS

    ... ok to start again. People who have a prosthesis, such as an artificial joint, need to carefully ... in your wallet that says you have a prosthesis. You will need to take antibiotics before any ...

  8. River Captures and Erosional Disequilibrium Along Strike-slip Faults

    NASA Astrophysics Data System (ADS)

    Brocard, G. Y.; Fayon, A. K.; Perg, L. A.; Paola, C.; Teyssier, C.; Whitney, D. L.; Mota, M.; Moran-Ical, S.

    2005-12-01

    River captures are internal instabilities of erosion systems and are inherently promoted by strike-slip faulting. A capture event can generate a wave of incision that propagates from the capture site upstream and/or downstream, resulting in an increased bulk erosion rate around the capture site. Thus, under steady boundary conditions, drainage diversions trigger pulses of erosion, sediment production, rock exhumation and isostatic rebound. Therefore, a significant part of the erosion in oblique tectonics can be achieved in a state of significant departure from short-term dynamic equilibrium. The frequency, intensity, and duration of these events set the timescale over which their integrated effects can be regarded as the expression of a long-term dynamic equilibrium. We are investigating the effects of a large river capture on the oblique collision between the North American and Caribbean plates in Guatemala. Several thousands of kilometers of strike-slip displacement have been accommodated along this boundary during the Tertiary. The deformation is now concentrated mostly along the E-W Motagua strike-slip fault. Oblique tectonics is discernable within a 50 km wide topographic belt, north of this fault (Sierra de las Minas - Sierra de Chuacus range). On the northern flank of this range, deformation includes 130 km offset across the Polochic strike-slip fault, documented by both geological structures and drainage patterns. Numerous elbows and dry valleys show the progressive transformation of the initial transverse (S-N) drainage crossing the fault into a transverse-parallel (E-W) system that developed during increasing displacement along the fault. The drainage reorganization operates by river lengthening, captures, and avulsions. One of the latest capture sites is surrounded by a large (110x30 km) zone of deeply (1500 m) dissected landscape that coincides with the captured catchment. This zone sharply contrasts with the surrounding areas where large fragments of a very subdued topography are preserved on the highlands. The capture has been interpreted as the diversion of the former headwaters of a westward flowing river located south of the fault (Rio Selegua) into a northward flowing river located north of the fault (Rio Chixoy), based on drainage pattern and preserved conglomerates. The capture event, the dissection of the landscape, and the uplift of the summit paleosurface are closely related, and likely Miocene in age. Newly discovered conglomerates confirm that the captured basin was drained by the Selegua River before being drained into the Chixoy River. Other newly discovered paleovalleys and conglomerates further document the expansion of the dissected captured watershed at the expense of surrounding catchments. Since the capture event, both the captured stream paleovalley and the subdued topography have been displaced by large normal faults, many of them striking parallel to the Polochic strike-slip fault. Recent faulted sediments on the Polochic Fault trace also display a significant vertical component of slip. The inception of this tectonic activity after the abandonment of the paleovalleys suggests that the faults may have accommodated the isostatic uplift that followed unloading of the captured drainage basin by erosion.

  9. Testing and analysis of mechanically-fastened lap joints

    NASA Astrophysics Data System (ADS)

    Pratt, John Dillworth

    Testing and analysis of flush-head bolted lap joints determined the effect of various factors on load-elongation behavior. The study included three bolt sizes in aluminum and titanium alloy panels. The investigation also covered a wide range of panel thicknesses. Three-dimensional nonlinear finite element analyses utilizing solid elements were used to model the load-elongation behavior of the joints. The primary focus of this research was the bolt head geometry, but the influence of other factors was also studied. Eight hundred and seventy models were analyzed, and the results were summarized into charts and tables as an aid to airframe designers. This research depended on the ability of the finite element method to reliably model the behavior of mechanically-fastened lap joints. Analytical models were built for three diverse fastener types for validation with experimental testing: solid rivets, blind bolts, and threaded bolts with nuts. Factors that influenced successful convergence of the analytical models were identified during this initial phase. These factors included the mesh density and distribution, contact constraints, material behavior, fastener installation strategy, and convergence tolerances. Fastener installation is a key factor that influences joint load-elongation behavior through induced cold work and clamping effects. As such, strategies were developed to model the squeezing of rivets, the bulbing of blind fasteners, and the tightening of nuts. A means for varying the convergence tolerance during an analysis was also developed and implemented. Fifty-nine analytical models were built and one hundred and eighteen experimental tests were conducted during a validation phase. In all cases, the load-elongation predictions are in excellent agreement with the experimental test results. Having established confidence in the analytical models, four studies of bolted joints were made. All four studies, in increasing levels of complexity, concerned the influence of various factors on the load-elongation behavior of bolted lap joints. The final study identified the most effective bolt head geometry for slip resistance over a range of panel thickness. Five head angles and four head heights were evaluated for three fastener sizes and three panel material types. Guides were then developed to aid designers in the selection of the most slip-resistant head geometry.

  10. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Rail joints. 213.351 Section 213.351 Transportation...at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise joint...

  11. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 2014-10-01 false Rail joints. 213.351 Section 213.351 Transportation...at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise joint...

  12. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Rail joints. 213.351 Section 213.351 Transportation...at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise joint...

  13. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 false Rail joints. 213.351 Section 213.351 Transportation...at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise joint...

  14. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 false Rail joints. 213.351 Section 213.351 Transportation...at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise joint...

  15. Wheat Gray Shorts for the Prevention of Slipped Tendons in Battery Brooder Chicks. 

    E-print Network

    Sherwood, R. M. (Ross Madison); Couch, James Russell

    1936-01-01

    brooders. The symptoms of slipped tendons in the advanced stages are these: the tibial-metatarsal jodnt is swollen and has a bluish-green color caused apparently by small hemorrhages in the underlying tissue, the tendons slip out of place to either side... STATION -- - A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS - BULLETIN 1 -- - JUNE, 1936 DIVISION OF POULTRY HUSBANDRY WHEAT GRAY SHORTS FOR THE PREVENTION OF SLIPPED TENDONS IN BATTERY BROODER CHICKS AGRICULTURAL AND MECHANICAL...

  16. Estimation of slip rate and fault displacement during shallow earthquake rupture in the Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Hamada, Yohei; Sakaguchi, Arito; Tanikawa, Wataru; Yamaguchi, Asuka; Kameda, Jun; Kimura, Gaku

    2015-12-01

    Enormous earthquakes repeatedly occur in subduction zones, and the slips along megathrusts, in particular those propagating to the toe of the forearc wedge, generate ruinous tsunamis. Quantitative evaluation of slip parameters (i.e., slip velocity, rise time and slip distance) of past slip events at shallow, tsunamigenic part of the fault is critical to characterize such earthquakes. Here, we attempt to quantify these parameters of slips that may have occurred along the shallow megasplay fault and the plate boundary décollement in the Nankai Trough, off southwest Japan. We apply a kinetic modeling to vitrinite reflectance profiles on the two fault rock samples obtained from Integrated Ocean Drilling Program (IODP). This approach constitutes two calculation procedures: heat generation and numerical profile fitting of vitrinite reflectance data. For the purpose of obtaining optimal slip parameters, residue calculation is implemented to estimate fitting accuracy. As the result, the measured distribution of vitrinite reflectance is reasonably fitted with heat generation rate and slip duration ( t r ) of 16,600 J/s/m2 and 6,250 s, respectively, for the megasplay and 23,200 J/s/m2 and 2,350 s, respectively, for the frontal décollement, implying slow and long-term slips. The estimated slip parameters are then compared with previous reports. The maximum temperature, Tmax, for the Nankai megasplay fault is consistent with the temperature constraint suggested by a previous work. Slow slip velocity, long-term rise time, and large displacement are recognized in these fault zones (both of the megasplay, the frontal décollement). These parameters are longer and slower than typical coseismic slip, but are rather consistent with rapid afterslip.

  17. The effect of bandwidth limitations on the inference of earthquake slip-weakening distance from seismograms

    USGS Publications Warehouse

    Spudich, P.; Guatteri, Mariagiovanna

    2004-01-01

    Numerous researchers have obtained estimates of slip-weakening distance, Dc, and fracture energy for recent earthquakes. Dc, is often observed to be a significant fraction of the total slip and tends to correlate with total slip. Although these observations may well be true of real earthquakes, we show that low-pass filtering of strong-motion seismograms can also produce some of these effects in inverted rupture models. We test the accuracy of Dc, estimates by calculating them in low-pass-filtered versions of models A and B of Guatteri and Spudich (2000). Models A and B are two different rupture models for a hypothetical M 6.5 earthquake, and they have nearly identical rupture time, slip, and stress-drop distributions, and nearly identical predicted seismograms, but Dc, for model B is about twice that for model A. By low-pass filtering slip models A and B at 1.0 Hz, we simulate the blurring effects of band-limited waveform inversions on these slip models. At each point on a fault, D???c is defined to be the slip at the time of the peak slip speed at that point. Low-pass filtering the slip models causes an upward bias in Dc inferred from stress-slip curves, and it causes an artificial correlation between D???c and the total slip. Low-pass filtering might also bias fracture energy high and radiated energy low. These biases should be considered when interpreting Dc derived from band-limited slip models of real earthquakes.

  18. Comparison of Three Different Slip Meters under Various Contaminated Conditions

    PubMed Central

    2012-01-01

    Objectives To challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results. Methods Four common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics. Results The contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and Ra, while the rest did not show statistical significance with surface roughness parameters (Ra, Rz). The English XL only showed statistical significance (p < 0.01) between slip index and contaminants. The static coefficient of friction obtained with the BOT-3000 showed good consistency and repeatability (CV < 0.1) as compared to the results for the BPT (CV > 0.2) and English XL (CV < 0.2). Conclusion It is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve. PMID:22953227

  19. Interchange Slip-Running Reconnection and Sweeping SEP-Beams

    NASA Technical Reports Server (NTRS)

    Masson, S.; Aulanier, G.; Pariat, E.; Klein, K.-L.

    2011-01-01

    We present a new model to explain how particles, accelerated at a reconnection site that is not magnetically connected to the Earth, could eventually propagate along the well-connected open flux tube. Our model is based on the results of a low-beta resistive magnetohydrodynamics simulation of a three-dimensional line-tied and initially current-free bipole, that is embedded in a non-uniform open potential field. The topology of this configuration is that of an asymmetric coronal null-point, with a closed fan surface and an open outer spine. When driven by slow photospheric shearing motions, field lines, initially fully anchored below the fan dome, reconnect at the null point, and jump to the open magnetic domain. This is the standard interchange mode as sketched and calculated in 2D. The key result in 3D is that, reconnected open field lines located in the vicinity of the outer spine, keep reconnecting continuously, across an open quasi-separatrix layer, as previously identified for non-open-null-point reconnection. The apparent slipping motion of these field lines leads to form an extended narrow magnetic flux tube at high altitude. Because of the slip-running reconnection, we conjecture that if energetic particles would be travelling through, or be accelerated inside, the diffusion region, they would be successively injected along continuously reconnecting field lines that are connected farther and farther from the spine. At the scale of the full Sun, owing to the super-radial expansion of field lines below 3 solar radius, such energetic particles could easily be injected in field lines slipping over significant distances, and could eventually reach the distant flux tube that is well-connected to the Earth.

  20. High pressure ceramic joint

    DOEpatents

    Ward, M.E.; Harkins, B.D.

    1993-11-30

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

  1. High pressure ceramic joint

    DOEpatents

    Ward, Michael E. (Poway, CA); Harkins, Bruce D. (San Diego, CA)

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  2. Quantification of Tsunami Bathymetry Effect on Finite Fault Slip Inversion

    NASA Astrophysics Data System (ADS)

    Bletery, Quentin; Sladen, Anthony; Delouis, Bertrand; Mattéo, Lionel

    2015-06-01

    The strong development of tsunami instrumentation in the past decade now provides observations of tsunami wave propagation in most ocean basins. This evolution has led to the wide use of tsunami data to image the complexity of earthquake sources. In particular, the 2011 Mw9.0 Tohoku-Oki earthquake is the first mega-event for which such a tsunami instrumentation network was available with an almost complete azimuthal coverage. Source inversion studies have taken advantage of these observations which add a lot of constrain on the solutions, especially in the shallow part of the fault models where other standard data sets tend to lack resolution: while on-land data are quite insensitive to slip on the often-distant shallow part of a subduction fault interface, tsunami observations are directly sensitive to the shallowest slip. And it is in this shallow portion that steep bathymetry combined with horizontal motion, the so-called bathymetry effect, can contribute to the tsunami excitation, in addition to the direct vertical sea-bottom deformation. In this study, we carefully investigate the different steps involved in the calculation of this bathymetry effect, from the initial sea-floor deformation to the prediction of the tsunami records, and evaluate its contribution across the main subduction zones of the world. We find that the bathymetry effect locally exceeds 10 % of the tsunami excitation in all subduction zones and 25 % in those known to produce the largest tsunami, either from mega- or tsunami- earthquakes. We then show how the bathymetry effect can modify the tsunami wave predictions, with time shifts of the wavefront and amplitudes sometimes varying by a factor of two. If the bathymetry effect can have a strong impact on the simulated tsunami, it will also affect the solution of the finite-fault slip inversion. We illustrate this later aspect in the case of the Tohoku-Oki earthquake. We find that not accounting for the bathymetry effect will not necessarily cause strong variations in the spatial extent of the inferred coseismic rupture but can severely distort the solution. We also find that the bathymetry effect improves the consistency of the slip model inverted from tsunami data with seafloor geodesy observations, implying that taking the bathymetry effect into account reduces the epistemic uncertainties on tsunami modeling. Implementing this easily quantifiable effect in the tsunami early warning system could thus lead to improved estimates of the tsunami impact across ocean basins.

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

    DOEpatents

    Gregory, D.L.; Priddy, T.G.; Smallwood, D.O.; Woodall, T.D.

    1991-06-18

    A vibration slip table for use in a vibration testing apparatus is disclosed. The tables comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes. 6 figures.

  4. The Van Fault, Eastern Turkey: A Preliminary Geological Slip Rate

    NASA Astrophysics Data System (ADS)

    Mackenzie, D.; Elliott, J. R.; Altunel, E.; Kurban, Y.; Walker, R. T.; Parsons, B.

    2014-12-01

    We present a preliminary quaternary slip-rate study on the Van fault, the source of the 2011 Mw7.1 reverse-slip earthquake which caused heavy damage to the cities of Van and Ercis, eastern Turkey. From the InSAR solution, we see a strong depth cut-off at 10km depth, above which there was no slip on the fault. We have carried out an investigation of the geomorphological expression of the fault in quaternary material, to determine whether the fault reaches the surface and, if so, whether this upper section could fail in an earthquake. On the western segment of the Van fault, we observe quaternary scarps coincident with the surface projection of the fault segment identified by InSAR, which displace quaternary alluvial fan and lake-bed deposits. These are coincident with the observation of fault gouge in quaternary deposits at a road cutting, providing evidence for a fault reaching the surface and suggesting that the upper section is capable of rupturing seismically. We use structure-from-motion photogrammetry, differential GPS and terrestrial LiDAR to determine offsets on two generations of fault scarps, and the creep offsets from the period following the earthquake. Preliminary radiocarbon and OSL dates from two uplifted terrace surfaces allow us to estimate a late quaternary geological slip-rate for the fault. Following the GPS and InSAR solution of Dogan et al. 2014 (GRL v41,i7), we also present field evidence and satellite image observations confirming the presence of a splay fault within the northern suburbs of Van city, which experienced creep following the 2011 earthquake. This fault is observed to be particularly evident in the early high resolution satellite imagery from the declassified CORONA missions, highlighting the potential for these datasets in identifying faults in areas now covered by urban sprawl. It remains unclear whether this fault could fail seismically. The fault which failed in 2011 is a north dipping reverse fault, unmapped prior to the earthquake. We identify similar geomorphological structures in the surrounding region, highlighting the need for further detailed tectonic mapping of the region.

  5. Wear and Cohesion During Frictional Slip Along Carbonate Faults

    NASA Astrophysics Data System (ADS)

    Reches, Z.; Chen, X.; Boneh, Y.; Madden, A. S.

    2013-12-01

    Our recent experiments with rotary shear of solid rock blocks showed that smoothening of carbonate faults during high-velocity slip leads to significant reduction of both friction and wear-rate. Chen et al. (2013) characterized roughness and friction down to sub-micron scale, and found that smoothing leads to friction reduction. They showed that friction coefficient correlates with surface roughness below 100 nm RMS roughness whereas no weakening occurred with higher roughness. Boneh et al. (2013) sheared limestone and dolomite fault at normal stress up to 7 MPa and slip-velocity up to 1 m/s during steady-state. At low velocities (V < 0.3 m/s), the wear-rate depends on the normal stress, as expected, but at higher velocities the wear-rates are low to vanishing with no dependence on the normal stress. Faults run at high-velocity displayed smooth, hard surfaces. These results allow quantifying the relations between wear, cohesion and friction. Frictional strength is the integrated effect of adhesion (= cohesion), fracturing (= wear), and plastic deformation along a slipping fault. The above results indicate that during the steady-state slip along the smooth, hard, wear-resistant surfaces of the experimental faults occurred with negligible fracturing and plastic deformation. Thus, adhesion became the dominant contributor to the frictional resistance. To test this hypothesis, the experimental cohesion, C, is compared with independently measured calcite adhesion. We use the Mohr diagram to calculate the cohesion of 22 experiments with Dover limestone, ran at velocities 0.005-0.31 m/s and normal stress up to 3 MPa, and 66 experiments with Kasota dolomite, ran at velocities 0.01-0.97 m/s and normal stress up to 7 MPa,. These calculations yielded C = 0.054 +/- 0.055 MPa for the limestone, and C = 0.463 +/- 0.190 MPa for the dolomite. Adhesion can be measured directly with Atomic-Force-Microscope (AFM) by using tiny cantilever with tips with tens of nm radius of curvature. We used several approaches to calculate calcite adhesion from the AFM measurements of Cubillas & Higgins (Geochemical transactions, 2009) and Lomboy et al. (Cement & Concrete Res., 2011) that were conducted on smooth surfaces of cleaved calcite either in air or in solution. We obtained a wide range for values from 0.2 MPa to 4.8 MPa, that are generally equal or higher than the cohesion in the limestone and dolomite experiments. The implications of these results to frictional faulting will be discussed.

  6. Slip effects associated with Knudsen transport phenomena in porous media

    NASA Technical Reports Server (NTRS)

    Frederking, T. H. K.; Hepler, W. A.; Khandhar, P. K.

    1988-01-01

    Porous media used in phase separators and thermomechanical pumps have been the subject of characterization efforts based on the Darcy permeability of laminar continuum flow. The latter is not always observed at low speed, in particular at permeabilities below 10 to the -9th/squared cm. The present experimental and theoretical studies address questions of slip effects associated with long mean free paths of gas flow at room temperature. Data obtained are in good agreement, within data uncertainty, with a simplified asymptotic Knudsen equation proposed for porous plugs on the basis of Knudsen's classical flow equation for long mean free paths.

  7. Effect of Inertia and Elasticity on Stick-Slip Motion

    NASA Astrophysics Data System (ADS)

    Luan, Binquan; Robbins, Mark O.

    2004-07-01

    A hybrid simulation method is used to study the transition from stick-slip motion to steady sliding as the sliding velocity increases above a critical value vc. The effects of the geometry, elasticity, and mass M of the sliding object are varied to test competing theories. When the slider has a tapered geometry, vc scales as M-1/2, and the elasticity of the slider is irrelevant. When the slider has a constant columnar cross section, elasticity dominates, and vc is independent of mass as M??. The tapered geometry is more typical of existing measurements, but the columnar geometry could be realized using a nanotube.

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

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency analysis for the Patua geothermal system was calculated based on faults mapped in the Hazen Quadrangle (Faulds et al., 2011). Patua lies near the margin between the Basin and Range province, which is characterized by west-northwest directed extension and the Walker Lane province, characterized by west-northwest directed dextral shear. As such, the Patua area likely has been affected by tectonic stress associated with either or both of stress regimes over geologic time. In order to characterize this stress variation we calculated slip tendency at Patua for both normal faulting and strike slip faulting stress regimes. Based on examination of regional and local stress data (as explained above) we applied at shmin direction of 105 to Patua. Whether the vertical stress (sv) magnitude is larger than ...

  9. Status of slip stacking at Fermilab Main Injector

    SciTech Connect

    Seiya, K.; Berenc, T.; Dey, J.; Chase, B.; Rivetta, C.; Kourbanis, I.; MacLachlan, J.; Meisner, K.; Pasquinelli, R.; Reid, J.; Steimel, J.; /Fermilab

    2005-05-01

    In order to achieve an increase in proton intensity, the Fermilab Main Injector (MI) will use a stacking process called ''slip stacking'' [1]. 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 been performed for this process and we have already verified that, at least for low beam intensities, the stacking procedure works as expected [2]. For high intensity operation, development work of the feedback and feedforward systems was done during the last machine shut down, from August to November 2004 [3].

  10. Dynamic Weakening by Acoustic Fluidization during Stick-Slip Motion

    NASA Astrophysics Data System (ADS)

    Giacco, F.; Saggese, L.; de Arcangelis, L.; Lippiello, E.; Pica Ciamarra, M.

    2015-09-01

    The unexpected weakness of some faults has been attributed to the emergence of acoustic waves that promote failure by reducing the confining pressure through a mechanism known as acoustic fluidization, also proposed to explain earthquake remote triggering. Here we validate this mechanism via the numerical investigation of a granular fault model system. We find that the stick-slip dynamics is affected only by perturbations applied at a characteristic frequency corresponding to oscillations normal to the fault, leading to gradual dynamical weakening as failure is approaching. Acoustic waves at the same frequency spontaneously emerge at the onset of failure in the absence of perturbations, supporting the relevance of acoustic fluidization in earthquake triggering.

  11. Analysis of laminar jet impingement and hydraulic jump on a horizontal surface with slip

    NASA Astrophysics Data System (ADS)

    Prince, Joseph F.; Maynes, Daniel; Crockett, Julie

    2012-10-01

    This paper explores the influence surface slip, uniform in all directions with constant slip length, exerts on the physics of laminar jet impingement on a flat horizontal surface. Slip exists on superhydrophobic surfaces, and due to the relatively thin film dynamics associated with the growth of the laminar jet after impingement, its influence on the fluid physics is significant. An analysis based on momentum considerations is presented that allows prediction of the relevant thin film parameters as a function of radial position from the impingement point, jet Reynolds number, and constant relative slip length of the surface. Further, the analysis allows determination of the hydraulic jump location in terms of laminar jet characteristics and imposed downstream liquid depth. The results reveal that at a given radial location, the boundary layer growth and thin film thickness decrease, while the surface velocity of the thin film increases with increasing slip at the surface. The departure from classical no-slip behavior is quantified over a range of realizable slip conditions. Increasing slip length also leads to formation of hydraulic jumps at increasing radial location. An expression based on the results is presented that allows prediction of the hydraulic jump location as a function of the magnitude of the slip and all other influencing variables.

  12. Strength of stick-slip and creeping subduction megathrusts from heat flow observations.

    PubMed

    Gao, Xiang; Wang, Kelin

    2014-08-29

    Subduction faults, called megathrusts, can generate large and hazardous earthquakes. The mode of slip and seismicity of a megathrust is controlled by the structural complexity of the fault zone. However, the relative strength of a megathrust based on the mode of slip is far from clear. The fault strength affects surface heat flow by frictional heating during slip. We model heat-flow data for a number of subduction zones to determine the fault strength. We find that smooth megathrusts that produce great earthquakes tend to be weaker and therefore dissipate less heat than geometrically rough megathrusts that slip mainly by creeping. PMID:25170149

  13. Earthquake slip vectors and estimates of present-day plate motions

    NASA Technical Reports Server (NTRS)

    Demets, Charles

    1993-01-01

    Two alternative models for present-day global plate motions are derived from subsets of the NUVEL-1 data in order to investigate the degree to which earthquake slip vectors affect the NUVEL-1 model and to provide estimates of present-day plate velocities that are independent of earthquake slip vectors. The data set used to derive the first model excludes subduction zone slip vectors. The primary purpose of this model is to demonstrate that the 240 subduction zone slip vectors in the NUVEL-1 data set do not greatly affect the plate velocities predicted by NUVEL-1. A data set that excludes all of the 724 earthquake slip vectors used to derive NUVEL-1 is used to derive the second model. This model is suitable as a reference model for kinematic studies that require plate velocity estimates unaffected by earthquake slip vectors. The slip-dependent slip vector bias along transform faults is investigated using the second model, and evidence is sought for biases in slip directions along spreading centers.

  14. Design study for a liquid metal slip ring solar array orientation mechanism

    NASA Technical Reports Server (NTRS)

    Clark, R. B.

    1972-01-01

    The design of a single axis orientation mechanism for solar arrays on high power synchronous satellites is studied primarily with respect to providing 116 liquid metal slip rings for reduced friction and improved electrical characteristics. Designs and tradeoff studies for the slip rings and other components are presented. An assembly containing 33 slip rings of three design approaches was designed, fabricated, and vacuum tested to 30 amperes and 30,000 volts. Containment of the liquid metal gallium in large diameter slip rings was difficult. A design approach is presented which is expected to provide improved retention of the liquid metal.

  15. Effects of Absolute Pressure and Dissolved Gasses on Apparent Fluid Slip in Hydrophobic Microchannels

    NASA Astrophysics Data System (ADS)

    Tretheway, Derek; Stone, Shannon; Meinhart, Carl

    2004-11-01

    Apparent fluid slip has been observed experimentally in micro- and nano-scale flow devices by several investigators (e.g. Tretheway and Meinhart (2002), Zhu and Granik (2001), Pit et.al (2000) and Bruer (2002)). Tretheway and Meinhart (2004) examined a possible mechanism for the generation of apparent fluid slip based on the observations of Lum et. al. (1999) who suggest a depleted water region or vapor layer develops near a hydrophobic surface and the observation of Ishida et al . and Tyrell et al. (2001) who observe nanobubbles at the surface. By modeling the presence of either a depleted layer or nanobubbles as an effective air gap at the wall, Tretheway and Meinhart (2004) calculated slip lengths for flow between two infinite parallel plates, which are consistent with experimental values. The results suggest that the relatively large apparent fluid slip observed experimentally at hydrophobic surfaces may arises from either the presence of nano-bubbles or a layer of low density fluid at the surface. Granick et al. (2003) suggest that the nature of saturated gasses plays a significant role in the generation of apparent fluid slip with water saturated with carbon dioxide showing no-slip and with argon showing massive slip. In this work, we explore the mechanism of Tretheway and Meinhart (2003) by measuring velocity profiles and calculating slip lengths at various absolute pressures and gas conditions (from degassed solutions to solutions saturated with various gasses). Preliminary results show that the measured slip length decreases with an increase in absolute pressure.

  16. Flow past superhydrophobic surfaces with cosine variation in local slip length

    E-print Network

    Asmolov, Evgeny S; Harting, Jens; Vinogradova, Olga I

    2012-01-01

    Anisotropic super-hydrophobic surfaces have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused mostly on cases of super-hydrophobic stripes. Here, we analyze a relevant situation of cosine variation of the local slip length. We derive approximate formulae for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that are in good agreement with the exact numerical solution and lattice-Bolzmann simulations for any surface slip fraction. The cosine texture can provide a very large effective (forward) slip, but it was found to be less efficient in generating a transverse flow as compared to super-hydrophobic stripes.

  17. Effect of Boundary Slip on The Load Support in A Lubricated Sliding Contact

    NASA Astrophysics Data System (ADS)

    Tauviqirrahman, M.; Ismail, R.; Jamari, J.; Schipper, D. J.

    2011-12-01

    In recent years it has been shown experimentally by a number of researchers that, for certain engineered surfaces, the no-slip boundary condition is not a valid one. Moreover, researchers demonstrate that slip patterning can considerably improve the performance of lubricated contact. In nano-electro-mechanical system (NEMS) containing moving components, there is a need to achieve low friction and high load support by lubrication. However, many researches were focused only on how to reduce the friction without paying much attention to the hydrodynamic pressure, i.e. load support. In this paper, the Reynolds model with slip boundary is presented for investigating the effect of slip boundary on the load support in a lubricated sliding contact. A finite volume method analysis is proposed in order to study the influence of boundary slip over the load support and friction. Numerical results of the extended Reynolds equation show that a homogeneously distributed slip boundary applied on a surface has a disadvantage with respect to the load support. It is found that in a lubricated system one of the lubricated surfaces is treated as homogeneous slip boundary, a lower load support with a reduced friction force is obtained. However, if that surface is designed as heterogeneous slip, i.e. partly boundary slip, the load support is about twice that of corresponding traditional sliding contact, even when there is no wedge effect.

  18. Mirror-like slip surfaces in dolostone: natural and experimental constraints on a potential seismic marker

    NASA Astrophysics Data System (ADS)

    Fondriest, M.; Smith, S. A.; Di Toro, G.; Nielsen, S. B.

    2012-12-01

    The lack of clear geological markers of seismic faulting represents a major limitation in our current comprehension of earthquake physics. At present pseudotachylytes (i.e. friction-induced melts) are the only unambiguously identified indicator of ancient seismicity in exhumed fault zones, but pseudotachylytes are not found in many rock types, including carbonates. We report the occurrence of small-displacement, mirror-like slip surfaces from a fault zone cutting dolostones. A combination of field observations and rotary shear friction experiments suggests that such slip surfaces: 1) are formed only at seismic slip rates, and 2) could potentially be used to estimate power dissipation during individual slip events. The Foiana Line (FL) is a major NNE-SSW-trending sinistral transpressive fault in the Italian Southern Alps. The outcropping fault zone consists of a <300 m wide zone of heavily fractured ("pulverized") dolostones cut by a network of mirror-like slip surfaces. The slip surfaces have displacements ranging between 0.04 m and 0.5 m and their mirror-like appearance indicates that the wavelength of surface roughness is <1 ?m. The slip surfaces have mainly dip-slip reverse kinematics and were exhumed from ~2 km depth. Resolved normal stress on the slip surfaces is estimated in the range 30-50 MPa. To understand how the mirror-like slip surfaces may have developed, slow- to high-velocity rotary-shear experiments using SHIVA (INGV, Rome) were performed on 3 mm thick layers of dolomite gouge (grain size <250 ?m) collected from the FL. Tests were conducted using a purpose-built gouge sample holder at slip rates of 0.0001-1.13 m/s, normal stresses up to 26 MPa and displacements in the range 0.02-3.5 m. At seismic slip rates of 1.13 m/s the dolomite gouge shows a dramatic reduction of the friction coefficient (?) from a peak value of ~0.7 to a steady-state value of ~0.25. The gouge starts to weaken above a threshold velocity in the range 0.19-0.49 m/s following a transient phase of strengthening. During the tests the instantaneous power density (shear stress*slip rate) dissipated on the sample reaches values of 6-10 MW/m2 over distances of 0.02-1 m, comparable to those of natural earthquakes. At 26 MPa normal stress a mirror-like slip surface is formed after only 0.03 m of slip. At intermediate slip rates (0.113 m/s) only moderate reductions in ? are observed. Instantaneous power density is ~1 MW/m2 and the mirror-like slip surface starts to develop after 0.1 m of slip. At sub-seismic slip rates (0.0001-0.0013 m/s) ? remains ~0.7, instantaneous power density is ~0.02 MW/m2, and no mirror-like slip surface develops. Microstructural observations suggest that the natural and experimental slip zones are comparable: both have a compacted layer up to 20 ?m thick immediately below the mirror-like slip surface in which deformation is strongly localized. The layer consists of partially-welded dolomite clasts 0.1-10 ?m in size. In the experimental samples, chemical analyses recognized small (<100 ?m long), discontinuous patches of periclase and Mg-calcite nanoparticles formed by dolomite decomposition. Field, experimental and microstructural data suggest that mirror-like slip surfaces in dolostone develop at seismic conditions, when instantaneous power density is of the order of 1-10 MW/m2.

  19. Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake.

    PubMed

    Romano, F; Piatanesi, A; Lorito, S; D'Agostino, N; Hirata, K; Atzori, S; Yamazaki, Y; Cocco, M

    2012-01-01

    The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ~48?m, up to ~35?m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment. PMID:22545193

  20. Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake

    PubMed Central

    Romano, F.; Piatanesi, A.; Lorito, S.; D'Agostino, N.; Hirata, K.; Atzori, S.; Yamazaki, Y.; Cocco, M.

    2012-01-01

    The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ~48?m, up to ~35?m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment. PMID:22545193

  1. Current slip rates on conjugate strike-slip faults in central Tibet using synthetic aperture radar interferometry

    E-print Network

    Taylor, Michael Halford; Peltzer, Gilles

    2006-12-09

    Himalaya syntaxis. This eastward movement initiated when the left-lateral slip ceased on the Red River Fault along with the extrusion of the Indochina Block in the mid-Miocene [Leloup et al., 1995; Tapponnier et al., 1990]. This kinematic relationship... echelon fault system as the Karakoram-Jiali fault zone (KJFZ) (Figure 1) and proposed it to be the structure along which eastward movement of the Qiangtang terrane relative to the Lhasa terrane is localized (Figure 1). Thus the KJFZ was inter- preted...

  2. Reassessment of the maximum magnitude of strike-slip earthquakes

    NASA Astrophysics Data System (ADS)

    Mignan, Arnaud; Danciu, Laurentiu; Giardini, Domenico

    2015-04-01

    What is the best approach of estimating the true maximum earthquake magnitude (Mmax)? This worst-case sce- nario can be defined as the less probable, never foreseen earthquake size but yet physically possible. Some authors have shown that earthquake observations are not sufficient to statistically estimate Mmax and that some long-term geological constraints should be used. We used as physical constraint the geometry of the fault network and its relation to the regional stress field. Criteria were then defined in a procedure - from the dynamic stress modelling literature - for estimating large cascading known faults into super-size fault lengths and then convert those into refined Mmax values. We developed an algorithm for multi-segment rupture and tested it on the strike-slip faults of the Anatolian Peninsula as defined in the 2013 European Seismic Hazard Model (ESHM13). We find that Mmax is increased locally from about 0.5 to 1.5 units along the North Anatolian Fault and the East Anatolian Fault. A number of other faults show an increase from about 0.5 to 1.0. With longer ruptures being characterized by greater slip and a wider shaking spatial footprint, our results infer a significant change in hazard for most of the Anatolian Peninsula once cascades are considered. Our algorithm is straightforward and does not require extensive calcula- tions, which should make it a simple add-on to consider for improving future stress tests and other seismic hazard analyses.

  3. Determination of regional stress tensors from fault-slip data

    NASA Astrophysics Data System (ADS)

    Xu, Peiliang

    2004-06-01

    Stress tensors are regularly determined from fault-slip and/or earthquake focal mechanism data in structural geology and seismotectonics. The inverse problem is non-linear, unless empirical rules of rupture and friction are employed. All the methods used to date to determine the stress tensor to this non-linear inverse problem are of a local nature, and thus cannot guarantee that the global optimal stress tensor has been obtained. We apply a hybrid global optimization method to find the global optimal stress tensor. Although the inverse problem is non-linear, the effect of non-linearity on the biases of stress tensors has not been investigated. We will examine the biases of inverted stress tensors and their effect on the principal orientations of stress and the shape parameter of the stress ellipsoid. The biases of stress parameters have been shown to be comparable with the estimated stress parameters numerically. We compare the accuracy of the four stress parameters, with and without taking the errors in fault planes into account. If the errors in fault planes are not taken into account, the stress parameters are too optimistically estimated by a factor of 4 to 9 in the example. We will also mathematically reformulate the assumption that the directions of maximum shear stress represent those of slips on fault planes as two functionally independent but equivalent constraints of equality. The new formulation is computationally more effective and provides a correct method for calculating the accuracy of stress parameters.

  4. Rolling, slip and traction measurements on low modulus materials

    NASA Technical Reports Server (NTRS)

    Tevaarwerk, J. L.

    1985-01-01

    Traction and wear tests were performed on six low modulus materials (LMM). Three different traction tests were performed to determine the suitability of the material for use as traction rollers. These were the rolling, slip and endurance traction tests. For each material the combination LMM on LMM and LMM on steel were evaluated. Rolling traction test were conducted to determine the load - velocity limits, the rolling traction coefficient of the materials and to establish the type of failures that would result when loading beyond the limit. It was found that in general a simple constant rolling traction coefficient was enough to describe the results of all the test. The slip traction tests revealed that the peak traction coefficients were considerably higher than for lubricated traction contacts. The endurance traction tests were performed to establish the durability of the LMM under conditions of prolonged traction. Wear measurements were performed during and after the test. Energetic wear rates were determined from the wear measurements conducted in the endurance traction tests. These values show that the roller wear is not severe when reasonable levels of traction are transmitted.

  5. Constructing constitutive relationships for seismic and aseismic fault slip

    USGS Publications Warehouse

    Beeler, N.M.

    2009-01-01

    For the purpose of modeling natural fault slip, a useful result from an experimental fault mechanics study would be a physically-based constitutive relation that well characterizes all the relevant observations. This report describes an approach for constructing such equations. Where possible the construction intends to identify or, at least, attribute physical processes and contact scale physics to the observations such that the resulting relations can be extrapolated in conditions and scale between the laboratory and the Earth. The approach is developed as an alternative but is based on Ruina (1983) and is illustrated initially by constructing a couple of relations from that study. In addition, two example constitutive relationships are constructed; these describe laboratory observations not well-modeled by Ruina's equations: the unexpected shear-induced weakening of silica-rich rocks at high slip speed (Goldsby and Tullis, 2002) and fault strength in the brittle ductile transition zone (Shimamoto, 1986). The examples, provided as illustration, may also be useful for quantitative modeling.

  6. Persistent earthquake clusters and gaps from slip on irregular faults

    NASA Astrophysics Data System (ADS)

    Parsons, Tom

    2008-01-01

    Earthquake-producing fault systems like the San Andreas fault in California show self-similar structural variation; earthquakes cluster in space, leaving aseismic gaps between clusters. Whether gaps represent overdue earthquakes or signify diminished risk is a question with which seismic-hazard forecasters wrestle. Here I use spectral analysis of the spatial distribution of seismicity along the San Andreas fault (for earthquakes that are at least 2 in magnitude), which reveals that it obeys a power-law relationship, indicative of self-similarity in clusters across a range of spatial scales. To determine whether the observed clustering of earthquakes is the result of a heterogeneous stress distribution, I use a finite-element method to simulate the motion of two rigid blocks past each other along a model fault surface that shows three-dimensional complexity on the basis of mapped traces of the San Andreas fault. The results indicate that long-term slip on the model fault generates a temporally stable, spatially variable distribution of stress that shows the same power-law relationship as the earthquake distribution. At the highest rates of San Andreas fault slip (40mmyr-1), stress patterns produced are stable over a minimum of 25,000 years before the model fault system evolves into a new configuration. These results suggest that although gaps are not immune to rupture propagation they are less likely to be nucleation sites for earthquakes.

  7. Unitary stick-slip motion in granular beds

    NASA Astrophysics Data System (ADS)

    Hilton, J. E.; Cleary, P. W.; Tordesillas, A.

    2013-06-01

    The dynamics of granular beds subject to applied stresses are often characterised by repeated cycles of stick-slip motion. The exact structural processes occurring during these repeated cycles are challenging to understand due to the complex multiparticle interactions within the material. Using a computational approach, we reduce the loading imposed on the system to the smallest possible component - a single particle within the bed. This simplified system allows us to isolate the contribution from a single unit of granular material to the overall response of the bed. We use the Discrete Element Method to model a packed, periodic, granular bed responding to the action of a single particle. The particle is drawn through the bed by means of a stiff virtual spring. Multiple stick-slip events in the bed are analysed by tracking of individual force chains and threecycles, enabling a comprehensive characterisation of their birth-death evolution. Our investigation allows us to link observed macroscopic dynamics with microscale behaviour, contributing towards a greater understanding of the continuum limit of granular materials.

  8. The earthquake cycle of strike-slip faults

    NASA Astrophysics Data System (ADS)

    Schmalzle, Gina M.

    An earthquake is a mechanism of stress release along plate boundaries due to relative motion between the Earth's lithospheric blocks. The period in which stresses are accruing across the plate boundary is known as the interseismic portion of the earthquake cycle. This dissertation focuses on interseismic portion of the earthquake cycle to extract characteristics of fault, shear zone and rock properties. Global Positioning System (GPS) data are used to observe the pattern of deformation across two primarily strike-slip fault systems: the Carrizo Segment of the San Andreas Fault (SAF) and the Eastern California Shear Zone (ECSZ). Two sets of GPS data are processed, analyzed and applied to analytic and numerical models describing the interseismic behavior of the earthquake cycle. The Carrizo segment is mature (i.e., had many earthquakes) and has juxtaposed terrains with varying rock properties laterally across the fault system. Lateral variations in rock properties affect the pattern of deformation around strike-slip faults affect how surrounding rock deforms and if not considered may bias the interpretation of the faulted system. The Carrizo segment separates Franciscan terrain northeast of the fault from Salinian block to the southwest. GPS data are well fit to a model with a 15-25 km weak zone northeast of the Carrizo segment. The long-term slip rate estimated on the SAF is 36+2-1.5 mm/yr, with 3 +/- 1 mm/yr accommodated on faults to the west. The viscosity for the combined lower crust/upper mantle is estimated at 2-5x10 19 Pa's. This model is consistent with the distribution of rock type and corresponding laboratory data on their material properties, paleoseismic, seismic and magnetotelluric data. The ECSZ is a young (<10 Myr) system of strike-slip faults including the Owens Valley - Airport Lake, Panamint Valley - Ash Hill - Hunter Mountain and Death Valley - Furnace Creek fault systems. The ECSZ study concentrates on fault evolution by finding the current position of maximum shear across the shear zone and estimating fault rates. Geologic studies suggest that the Death Valley - Furnace Creek fault system on eastern end of the ECSZ was the primary accommodator of slip early in the ECSZ history. This study suggests that the current locus of shear has shifted westward, and resides in the center of the ECSZ under the Panamint Valley - Ash Hill - Hunter Mountain fault system. The model dependent estimated geodetic rate of the Ash Hill - Panamint Valley - Hunter Mountain fault system ( 5.51+0.58-0.60 mm/yr) is faster than geologic estimates (1.6--4 mm/yr). The result is interpreted as a simplification of the ECSZ with time, combined with progressive westward migration of deformation. The best estimate for a combined rate across the shear zone is 10 mm/yr (20% of total Pacific-North America motion). The summation of rates obtained by this study is 49 mm/yr, well within estimates obtained by previous studies using independent techniques.

  9. Predicting the probability of slip in gait: methodology and distribution study.

    PubMed

    Gragg, Jared; Yang, James

    2016-01-01

    The likelihood of a slip is related to the available and required friction for a certain activity, here gait. Classical slip and fall analysis presumed that a walking surface was safe if the difference between the mean available and required friction coefficients exceeded a certain threshold. Previous research was dedicated to reformulating the classical slip and fall theory to include the stochastic variation of the available and required friction when predicting the probability of slip in gait. However, when predicting the probability of a slip, previous researchers have either ignored the variation in the required friction or assumed the available and required friction to be normally distributed. Also, there are no published results that actually give the probability of slip for various combinations of required and available frictions. This study proposes a modification to the equation for predicting the probability of slip, reducing the previous equation from a double-integral to a more convenient single-integral form. Also, a simple numerical integration technique is provided to predict the probability of slip in gait: the trapezoidal method. The effect of the random variable distributions on the probability of slip is also studied. It is shown that both the required and available friction distributions cannot automatically be assumed as being normally distributed. The proposed methods allow for any combination of distributions for the available and required friction, and numerical results are compared to analytical solutions for an error analysis. The trapezoidal method is shown to be highly accurate and efficient. The probability of slip is also shown to be sensitive to the input distributions of the required and available friction. Lastly, a critical value for the probability of slip is proposed based on the number of steps taken by an average person in a single day. PMID:25563532

  10. Recurrent slow slip event reveals the interaction with seismic slow earthquakes and disruption from large earthquake

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Moore, Angelyn W.; Owen, Susan

    2015-09-01

    It remains enigmatic how slow slip events (SSEs) interact with other slow seismic events and large distant earthquakes at many subduction zones. Here we model the spatiotemporal slip evolution of the most recent long-term SSE in 2009-2011 in the Bungo Channel region, southwest Japan using GEONET GPS position time-series and a Kalman filter-based, time-dependent slip inversion method. We examine the space-time relationship between the geodetically determined slow slip transient and seismically observed low frequency earthquakes (LFEs) and very-low frequency earthquakes (V-LFEs) near the Nankai trough. We find a strong but distinct temporal correlation between transient slip and LFEs and V-LFEs, suggesting a different relationship to the SSE. We also find the great Tohoku-Oki earthquake appears to disrupt the normal source process of the SSE, probably reflecting large-scale stress redistribution caused by the earthquake. Comparison of the 2009-2011 SSE with others in the same region shows much similarity in slip and moment release, confirming its recurrent nature. Comparison of transient slip with plate coupling shows that slip transients mainly concentrate on the transition zone from strong coupling region to downdip LFEs with transient slip relieving elastic strain accumulation at transitional depth. The less consistent spatial correlation between the long-term SSE and seismic slow earthquakes, and susceptibility of these slow earthquakes to various triggering sources including long-term slow slip, suggests caution in using the seismically determined slow earthquakes as a proxy for slow slip.

  11. Temporal Feasibility of Rapid Joint Inversions in Response to Tsunamis Triggered by Megathrust Earthquakes

    NASA Astrophysics Data System (ADS)

    Williamson, A.; Newman, A. V.

    2014-12-01

    Joint inversions of sub-areal surface deformation and tsunami waves generated by seafloor ground motions, while still in their infancy, have the opportunity for realistic representations of megathrust earthquake slip responsible, which occurs primarily offshore. Such joint inversions, including Gusman, et al. [JGR, 2010] and Wei et al. [PAGEOPH, 2014], highlight fault slip unobservable with on land measurements alone. Careful detection of possible slip patterns can affect how nearby communities prepare for future events, therefore their discovery is important for hazard mitigation. Joint inversions could also prove invaluable during a large even through a rapid inversion of real time data. This study looks at the availability and accessibility of land-based GPS and deep-ocean pressure sensor data for rapid join inversions, and the latency between such solutions and both local and global tsunami wave arrivals. We consider GPS rather than other ground-based deformation techniques because of its ability to provide rapid and continuous translations of the ground surface. For tsunami observations, we focus on deep-ocean pressure sensors such as those used in DART systems, because of similarly rapid and continues data availability. Similarly tsunami waves traveling through the deep-ocean have negligible non-linear components, making them ideal for inversion methods. We create a source event in a zone with an elevated seismic risk and then track tsunami travel times to the coast and the nearest deep-ocean pressure sensors to determine a temporal limit to warnings that can be issued to nearby regions. By assessing this latency, focus can be given to areas where an inversion of this type has the potential to improve warning information. This study also identifies regions that lack necessary on and offshore instrumentation to warn coastal communities at risk for tsunamigenic earthquakes. By assessing the feasibility of joint inversions, it becomes easier to move forward with future studies focusing on regions that would see the largest benefit in real-time hazard mitigation.

  12. Dissimilar metals joint evaluation

    NASA Technical Reports Server (NTRS)

    Wakefield, M. E.; Apodaca, L. E.

    1974-01-01

    Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

  13. 13. Sacroiliac joint pain.

    PubMed

    Vanelderen, Pascal; Szadek, Karolina; Cohen, Steven P; De Witte, Jan; Lataster, Arno; Patijn, Jacob; Mekhail, Nagy; van Kleef, Maarten; Van Zundert, Jan

    2010-01-01

    The sacroiliac joint accounts for approximately 16% to 30% of cases of chronic mechanical low back pain. Pain originating in the sacroiliac joint is predominantly perceived in the gluteal region, although pain is often referred into the lower and upper lumbar region, groin, abdomen, and/ or lower limb(s). Because sacroiliac joint pain is difficult to distinguish from other forms of low back pain based on history, different provocative maneuvers have been advocated. Individually, they have weak predictive value, but combined batteries of tests can help ascertain a diagnosis. Radiological imaging is important to exclude "red flags" but contributes little in the diagnosis. Diagnostic blocks are the diagnostic gold standard but must be interpreted with caution, because false-positive as well as false-negative results occur frequently. Treatment of sacroiliac joint pain is best performed in the context of a multidisciplinary approach. Conservative treatments address the underlying causes (posture and gait disturbances) and consist of exercise therapy and manipulation. Intra-articular sacroiliac joint infiltrations with local anesthetic and corticosteroids hold the highest evidence rating (1 B+). If the latter fail or produce only short-term effects, cooled radiofrequency treatment of the lateral branches of S1 to S3 (S4) is recommended (2 B+) if available. When this procedure cannot be used, (pulsed) radiofrequency procedures targeted at L5 dorsal ramus and lateral branches of S1 to S3 may be considered (2 C+). PMID:20667026

  14. New Joint Sealants. Criteria, Design and Materials.

    ERIC Educational Resources Information Center

    Building Research Inst., Inc., Washington, DC.

    Contents include--(1) sealing concrete joints, (2) sealing glass and metal joints, (3) metal and glass joint sealants from a fabricator's viewpoint, (4) a theory of adhesion for joint sealants, (5) geometry of simple joint seals under strain, (6) joint sealant specifications from a manufacturer's viewpoint, (7) joint sealant requirements from an…

  15. On the question of whether lubricants fluidize in stick–slip friction

    PubMed Central

    Rosenhek-Goldian, Irit; Kampf, Nir; Yeredor, Arie; Klein, Jacob

    2015-01-01

    Intermittent sliding (stick–slip motion) between solids is commonplace (e.g., squeaking hinges), even in the presence of lubricants, and is believed to occur by shear-induced fluidization of the lubricant film (slip), followed by its resolidification (stick). Using a surface force balance, we measure how the thickness of molecularly thin, model lubricant films (octamethylcyclotetrasiloxane) varies in stick–slip sliding between atomically smooth surfaces during the fleeting (ca. 20 ms) individual slip events. Shear fluidization of a film of five to six molecular layers during an individual slip event should result in film dilation of 0.4–0.5 nm, but our results show that, within our resolution of ca. 0.1 nm, slip of the surfaces is not correlated with any dilation of the intersurface gap. This reveals that, unlike what is commonly supposed, slip does not occur by such shear melting, and indicates that other mechanisms, such as intralayer slip within the lubricant film, or at its interface with the confining surfaces, may be the dominant dissipation modes. PMID:26039993

  16. Slip sequences in laboratory experiments as analogues to earthquakes associated with a fault edge

    E-print Network

    Fineberg, Jay

    Slip sequences in laboratory experiments as analogues to earthquakes associated with a fault edge and steps are common. We experimentally explore how fault edges may affect earthquake and slip dynamics both earthquake nucleation processes and the evolution of fault complexity. 1 INTRODUCTION Faults

  17. Anisotropic particle in viscous shear flow: Navier slip, reciprocal symmetry, and Jeffery orbit.

    PubMed

    Zhang, Jiaolong; Xu, Xinpeng; Qian, Tiezheng

    2015-03-01

    The hydrodynamic reciprocal theorem for Stokes flows is generalized to incorporate the Navier slip boundary condition, which can be derived from Onsager's variational principle of least energy dissipation. The hydrodynamic reciprocal relations and the Jeffery orbit, both of which arise from the motion of a slippery anisotropic particle in a simple viscous shear flow, are investigated theoretically and numerically using the fluid particle dynamics method [Phys. Rev. Lett. 85, 1338 (2000)]. For a slippery elliptical particle in a linear shear flow, the hydrodynamic reciprocal relations between the rotational torque and the shear stress are studied and related to the Jeffery orbit, showing that the boundary slip can effectively enhance the anisotropy of the particle. Physically, by replacing the no-slip boundary condition with the Navier slip condition at the particle surface, the cross coupling between the rotational torque and the shear stress is enhanced, as manifested through a dimensionless parameter in both of the hydrodynamic reciprocal relations and the Jeffery orbit. In addition, simulations for a circular particle patterned with portions of no-slip and Navier slip are carried out, showing that the particle possesses an effective anisotropy and follows the Jeffery orbit as well. This effective anisotropy can be tuned by changing the ratio of no-slip portion to slip potion. The connection of the present work to nematic liquid crystals' constitutive relations is discussed. PMID:25871211

  18. Study of the pore structure of ceramics prepared by the slip casting method

    NASA Technical Reports Server (NTRS)

    Guzman, I. Y.; Dobysh, A. V.

    1984-01-01

    The porosity of the slip cast Si3N4 is similar to that of pressed Si3N4 formed at 2500 kg/sq cm. The porosity of cast Si oxynitride is equivalent to that of samples stressed at 10,000 kg/sq cm. Crucibles formed from these materials by slip casting have high thermal shock and corrosion resistance.

  19. Effective normal stress alteration due to pore pressure changes induced by dynamic slip

    E-print Network

    Effective normal stress alteration due to pore pressure changes induced by dynamic slip propagation and permeabilities causes a change in pore pressure there. Because slip causes compression on one side of the fault wall and extension on the other, the pore pressure on the fault increases substantially when

  20. Connecting Earthquakes and Violins: Investigations Illustrate Stick-Slip Frictional Motion as a Common Thread

    ERIC Educational Resources Information Center

    Ringlein, James

    2005-01-01

    Violins, earthquakes, and the "singing rod" demonstration all have something in common--stick-slip frictional motion. The application of stick-slip friction can be extended to a ringing wineglass, exotic percussion instruments, car racing, and the latest research on the interplay between surfaces at the atomic level. These examples all involve two…

  1. "A Chance Child": Jill Paton Walsh and the Re-Invention of the Time Slip Story

    ERIC Educational Resources Information Center

    Hall, Linda Marian

    2011-01-01

    In this study of Jill Paton Walsh's one time-slip novel, I attempt to show how she reinvents the genre by giving as much prominence to the dislocated present as she does to the sufferings of children caught up in the horrors of the Industrial Revolution. Where previous time-slip authors had concentrated on the past, she addresses clearly unwelcome…

  2. Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake

    E-print Network

    Socquet, Anne

    Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake Fred F. Pollitz by the February 27, 2010 Mw = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip] The February 27, 2010 Maule, Chile earthquake rup- tured about 650 km of the Andean megathrust in a bilateral

  3. Heating and weakening of faults during earthquake slip James R. Rice1

    E-print Network

    strength for a given friction coefficient and (2) flash heating at highly stressed frictional microcontacts during rapid slip, which reduces the friction coefficient. (Macroscopic melting, or possibly gel materials and lab friction studies at high slip rates. Predictions are that strength drop should often

  4. Private Middle School Parents' Perspectives Regarding School-Located Immunization Programs (SLIPs)

    ERIC Educational Resources Information Center

    Venkatesh, Sheila R.; Acosta, Amy B.; Middleman, Amy B.

    2013-01-01

    The perspectives of parents of private middle school students regarding the use of school-located immunization programs (SLIPs) are unknown. Parents of private middle school students in a large, urban setting were surveyed "N" = 1,210) regarding their willingness to use SLIPs. Analyses included frequencies and chi-square analyses. Data…

  5. Hierarchic three-dimensional structure and slip partitioning in the western Dead Sea pull-apart

    E-print Network

    Ze'ev, Reches

    Hierarchic three-dimensional structure and slip partitioning in the western Dead Sea pull the internal structure of such a belt, the western margins of the Dead Sea basin. This basin is 150 km long, 15­20 km wide with more than 10 km of sediment fill; and it is currently subsiding due to slip of the Dead

  6. Slip rate and locking depth from GPS profiles across the southern Dead Sea Transform

    E-print Network

    Klinger, Yann

    Slip rate and locking depth from GPS profiles across the southern Dead Sea Transform Maryline Le 2008; published 6 November 2008. [1] The Dead Sea Transform is a major strike-slip fault bounding the present-day deformation across the southern segment of the Dead Sea Transform, the Wadi Araba fault

  7. Path Following using Visual Odometry for a Mars Rover in High-Slip Environments1

    E-print Network

    Roumeliotis, Stergios I.

    1 Path Following using Visual Odometry for a Mars Rover in High-Slip Environments1 Daniel M Drive Pasadena, CA 91109 818-354-3226 firstname.lastname@jpl.nasa.gov Stergios I. Roumeliotis University for autonomous operation of Mars rovers in high slip environments has been designed, implemented, and tested

  8. On the deviatoric normal stress on a slip surface Kang Ping Chen and William Saric

    E-print Network

    On the deviatoric normal stress on a slip surface Kang Ping Chen and William Saric Department February 2000; accepted 4 September 2000 A general formula for the deviatoric normal stress on a slip of Physics. S1070-6631 00 00612-7 When studying viscous flow over a deformable surface, knowledge

  9. Volcanic drumbeat seismicity caused by stick-slip motion and magmatic frictional melting

    NASA Astrophysics Data System (ADS)

    Kendrick, J. E.; Lavallée, Y.; Hirose, T.; di Toro, G.; Hornby, A. J.; de Angelis, S.; Dingwell, D. B.

    2014-06-01

    During volcanic eruptions, domes of solidifying magma can form at the volcano summit. As magma ascends it often forms a plug bounded by discrete fault zones, a process accompanied by drumbeat seismicity. The repetitive nature of this seismicity has been attributed to stick-slip motion at fixed loci between the rising plug of magma and the conduit wall. However, the mechanisms for such periodic motion remain controversial. Here we simulate stick-slip motion in the laboratory using high-velocity rotary-shear experiments on magma-dome samples collected from Soufrière Hills Volcano, Montserrat, and Mount St Helens Volcano, USA. We frictionally slide the solid magma samples to generate slip analogous to movement between a magma plug and the conduit wall. We find that frictional melting is a common consequence of such slip. The melt acts as a viscous brake, so that the slip velocity wanes as melt forms. The melt then solidifies, followed by pressure build up, which allows fracture and slip to resume. Frictional melt therefore provides a feedback mechanism during the stick-slip process that can accentuate the cyclicity of such motion. We find that the viscosity of the frictional melt can help define the recurrence interval of stick-slip events. We conclude that magnitude, frequency and duration of drumbeat seismicity depend in part on the composition of the magma.

  10. Fault slip rates from three-dimensional models of the Los Angeles metropolitan area, California

    E-print Network

    Cooke, Michele

    Fault slip rates from three-dimensional models of the Los Angeles metropolitan area, California Angeles region to use non-planar, geologically representative fault surfaces compiled by the Southern California Earthquake Center Community Fault Model. The fault slip rates from our three-dimensional model

  11. Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project

    E-print Network

    Ma, Kuo-Fong

    LETTERS Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling and development of a fault zone requires a combination of both seismological and geo- logical field data1 . The actual thickness of the zone that slips dur- ing the rupture of a large earthquake is not known

  12. A structural equation modelling approach examining the pathways between safety climate, behaviour performance and workplace slipping

    PubMed Central

    Swedler, David I; Verma, Santosh K; Huang, Yueng-Hsiang; Lombardi, David A; Chang, Wen-Ruey; Brennan, Melayne; Courtney, Theodore K

    2015-01-01

    Objective Safety climate has previously been associated with increasing safe workplace behaviours and decreasing occupational injuries. This study seeks to understand the structural relationship between employees’ perceptions of safety climate, performing a safety behaviour (ie, wearing slip-resistant shoes) and risk of slipping in the setting of limited-service restaurants. Methods At baseline, we surveyed 349 employees at 30 restaurants for their perceptions of their safety training and management commitment to safety as well as demographic data. Safety performance was identified as wearing slip-resistant shoes, as measured by direct observation by the study team. We then prospectively collected participants’ hours worked and number of slips weekly for the next 12?weeks. Using a confirmatory factor analysis, we modelled safety climate as a higher order factor composed of previously identified training and management commitment factors. Results The 349 study participants experienced 1075 slips during the 12-week follow-up. Confirmatory factor analysis supported modelling safety climate as a higher order factor composed of safety training and management commitment. In a structural equation model, safety climate indirectly affected prospective risk of slipping through safety performance, but no direct relationship between safety climate and slips was evident. Conclusions Results suggest that safety climate can reduce workplace slips through performance of a safety behaviour as well as suggesting a potential causal mechanism through which safety climate can reduce workplace injuries. Safety climate can be modelled as a higher order factor composed of safety training and management commitment. PMID:25710968

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

    E-print Network

    Goldfinger, Chris

    Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake August 2012; published 9 October 2012. [1] We test hypothetical tsunami scenarios against a 4,600-year for prehistoric Cascadia tsunamis. Tsunami simulations constrain coseismic slip estimates for the southern

  14. Vapourliquid slip in a parallel-plate electrochemical uorination reactor , G.L. BAUER2

    E-print Network

    Weidner, John W.

    . This is in contrast to recent models of more typical systems where the rate of the parasitic reaction (i.e., H2 is shown at dierent ¯ow rates over a wide current range. It was found that slip of the gas past the liquid rates. Under these more severe operating conditions, slip signi®cantly reduces the cell voltage

  15. Overview of cenozoic strike-slip displacement of the caribbean plate

    SciTech Connect

    Mann, P.

    1985-01-01

    Geologic and tectonic studies in the Caribbean region have traditionally focused on Cretaceous and Paleogene arc rocks which, for the most part, record a long period (approx. = 100 Ma) of plate convergence. Since the recognition of the plate structure of the Caribbean by Molnar and Sykes in 1969, there has been steadily increasing interest in mapping widespread ares of Neogene sedimentary and volcanic rocks that generally record a long period (65.-40 Ma) of eastward displacement of the Caribbean plate relative to the Americas. The purpose of this talk is to review different aspects of present knowledge on this strike-slip displacement, namely: 1) location of major strike-slip faults within the northern and southern plate boundary zones; 2) sense, offset, rate of slip of major strike-slip faults; 3) secondary deformational features related to strike-slip displacements; 4) intraplate deformational features related to interplate strike-slip movements; 5) relation of seismicity to major strike-slip faults; and 6) constraints imposed by strike-slip fault systems on plate motion models. Based on these observations, several critical problems which future studies might help resolve are pointed out.

  16. BLAST FURNACE SLIPS AND ACCOMPANYING EMISSIONS AS AN AIR POLLUTION SOURCE

    EPA Science Inventory

    The report gives results of a study to ascertain the severity of blast-furnace slips and their accompanying bleeder-valve emissions as a source of air pollution. It describes factors contributing to the occurrence of hangs and slips in the blast furnace. It discusses the mechanic...

  17. Effective Slip over Superhydrophobic Surfaces in Thin Channels Francois Feuillebois,1

    E-print Network

    Bazant, Martin Z.

    Effective Slip over Superhydrophobic Surfaces in Thin Channels Franc¸ois Feuillebois,1 Martin Z; published 15 January 2009) Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces. DOI

  18. 33 CFR 165.751 - Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Security Zone: LNG mooring slip... § 165.751 Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia. (a) Security zone. The... security zone; or (4) Actively engaged in escort, maneuvering, or support duties for an LNG tankship....

  19. 33 CFR 165.751 - Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Security Zone: LNG mooring slip... § 165.751 Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia. (a) Security zone. The... security zone; or (4) Actively engaged in escort, maneuvering, or support duties for an LNG tankship....

  20. 33 CFR 165.751 - Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone: LNG mooring slip... § 165.751 Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia. (a) Security zone. The... security zone; or (4) Actively engaged in escort, maneuvering, or support duties for an LNG tankship....

  1. 33 CFR 165.751 - Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone: LNG mooring slip... § 165.751 Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia. (a) Security zone. The... security zone; or (4) Actively engaged in escort, maneuvering, or support duties for an LNG tankship....

  2. 33 CFR 165.751 - Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone: LNG mooring slip... § 165.751 Security Zone: LNG mooring slip, Savannah River, Savannah, Georgia. (a) Security zone. The... security zone; or (4) Actively engaged in escort, maneuvering, or support duties for an LNG tankship....

  3. Slipping and Tripping Reflexes for Bipedal Robots Gary N. Boone and Jessica K. Hodgins

    E-print Network

    errors. We present simulation trials for single­slip tasks with varying coefficients of friction on such relatively simple rough terrain as stairs, curbs, grass, and slopes. Even smooth terrain becomes difficult to re­ cover from slipping on low friction surfaces and tripping over small obstacles (Figure 1). Many

  4. On the question of whether lubricants fluidize in stick-slip friction.

    PubMed

    Rosenhek-Goldian, Irit; Kampf, Nir; Yeredor, Arie; Klein, Jacob

    2015-06-01

    Intermittent sliding (stick-slip motion) between solids is commonplace (e.g., squeaking hinges), even in the presence of lubricants, and is believed to occur by shear-induced fluidization of the lubricant film (slip), followed by its resolidification (stick). Using a surface force balance, we measure how the thickness of molecularly thin, model lubricant films (octamethylcyclotetrasiloxane) varies in stick-slip sliding between atomically smooth surfaces during the fleeting (ca. 20 ms) individual slip events. Shear fluidization of a film of five to six molecular layers during an individual slip event should result in film dilation of 0.4-0.5 nm, but our results show that, within our resolution of ca. 0.1 nm, slip of the surfaces is not correlated with any dilation of the intersurface gap. This reveals that, unlike what is commonly supposed, slip does not occur by such shear melting, and indicates that other mechanisms, such as intralayer slip within the lubricant film, or at its interface with the confining surfaces, may be the dominant dissipation modes. PMID:26039993

  5. Slow slip predictions based on granite and gabbro friction data compared to GPS measurements

    E-print Network

    Slow slip predictions based on granite and gabbro friction data compared to GPS measurements friction data of granite and gabbro gouges under hydrothermal conditions to a Cascadia-like 2-D model and extrapolating the 2-D fault slip to a 3-D distribution, we find that the friction data for gabbro gouge

  6. Distribution of slip from 11 Mw > 6 earthquakes in the northern Chile subduction zone

    E-print Network

    Simons, Mark

    Distribution of slip from 11 Mw > 6 earthquakes in the northern Chile subduction zone M. E in northern Chile (23°­25°S) between the years 1993 and 2000. We invert body wave waveforms and geodetic data. Simons (2006), Distribution of slip from 11 Mw > 6 earthquakes in the northern Chile subduction zone, J

  7. Prosthetic Joint Infection

    PubMed Central

    Tande, Aaron J.

    2014-01-01

    SUMMARY Prosthetic joint infection (PJI) is a tremendous burden for individual patients as well as the global health care industry. While a small minority of joint arthroplasties will become infected, appropriate recognition and management are critical to preserve or restore adequate function and prevent excess morbidity. In this review, we describe the reported risk factors for and clinical manifestations of PJI. We discuss the pathogenesis of PJI and the numerous microorganisms that can cause this devastating infection. The recently proposed consensus definitions of PJI and approaches to accurate diagnosis are reviewed in detail. An overview of the treatment and prevention of this challenging condition is provided. PMID:24696437

  8. Tremor–genic slow slip regions may be deeper and warmer and may slip slower than non–tremor–genic regions

    DOE PAGESBeta

    Montgomery-Brown, E. K.; Syracuse, E. M.

    2015-09-17

    The slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kilauea Volcano, Hawaii, the Boso Peninsula, Japan, {near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor including: slip velocity, pressure, temperature, fluidsmore »and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kilauea Volcano (~10?? m/s) and Boso Peninsula (~10?? m/s) are among the fastest SSEs worldwide. Kilauea Volcano, the Boso Peninsula and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. {Fluids also likely contribute to tremor generation, and no corresponding zone of high vp/vs has been noted at Kilauea or Boso. We suggest that the relatively faster slip velocities at Kilauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.« less

  9. Tremor–genic slow slip regions may be deeper and warmer and may slip slower than non–tremor–genic regions

    SciTech Connect

    Montgomery-Brown, E. K.; Syracuse, E. M.

    2015-09-17

    The slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kilauea Volcano, Hawaii, the Boso Peninsula, Japan, {near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor including: slip velocity, pressure, temperature, fluids and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kilauea Volcano (~10?? m/s) and Boso Peninsula (~10?? m/s) are among the fastest SSEs worldwide. Kilauea Volcano, the Boso Peninsula and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. {Fluids also likely contribute to tremor generation, and no corresponding zone of high vp/vs has been noted at Kilauea or Boso. We suggest that the relatively faster slip velocities at Kilauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

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

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency for the Tuscarora geothermal field was calculated based on the faults mapped Tuscarora area (Dering, 2013). The Tuscarora area lies in the Basin and Range Province, as such we applied a normal faulting stress regime to the Tuscarora area faults, with a minimum horizontal stress direction oriented 115, based on inspection of local and regional stress determinations, as explained above. Under these stress conditions north-northeast striking, steeply dipping fault segments have the highest dilation tendency, while north-northeast striking 60° dipping fault segments have the highest tendency to slip. Tuscarora is defined by a left-step in a major north- to-north northeast striking, west-dipping range-bounding normal fault system. Faults within the broad step define an anticlinal accommodation zone...

  11. Qubit quantum-dot sensors: noise cancellation by coherent backaction, initial slips, and elliptical precession

    E-print Network

    M. Hell; M. R. Wegewijs; D. P. DiVincenzo

    2015-08-21

    We theoretically investigate the backaction of a sensor quantum dot with strong local Coulomb repulsion on the transient dynamics of a qubit that is probed capacitively. We show that the measurement backaction induced by the noise of electron cotunneling through the sensor is surprisingly mitigated by the recently identified coherent backaction [PRB 89, 195405] arising from quantum fluctuations. This renormalization effect is missing in semiclassical stochastic fluctuator models and typically also in Born-Markov approaches, which try to avoid the calculation of the nonstationary, nonequilibrium state of the qubit plus sensor. Technically, we integrate out the current-carrying electrodes to obtain kinetic equations for the joint, nonequilibrium detector-qubit dynamics. We show that the sensor-current response, level renormalization, cotunneling, and leading non-Markovian corrections always appear together and cannot be turned off individually in an experiment or ignored theoretically. We analyze the backaction on the reduced qubit state - capturing the full non-Markovian effects imposed by the sensor quantum dot on the qubit - by applying a Liouville-space decomposition into quasistationary and rapidly decaying modes. Importantly, the sensor cannot be eliminated completely even in the simplest high-temperature, weak-measurement limit: The qubit state experiences an initial slip that persists over many qubit cycles and depends on the initial preparation of qubit plus sensor quantum dot. A quantum-dot sensor can thus not be modeled as a 'black box' without accounting for its dynamical variables. We furthermore find that the Bloch vector relaxes (T1) along an axis that is not orthogonal to the plane in which the Bloch vector dephases (T2), blurring the notions of T1 and T2 times. Finally, the precessional motion of the Bloch vector is distorted into an ellipse in the tilted dephasing plane.

  12. INDUCED SEISMICITY. Seismicity triggered by fluid injection-induced aseismic slip.

    PubMed

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

    2015-06-12

    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 (?m/s)] aseismic slip associated with a 20-fold increase of permeability, which transitions to faster slip (~10 ?m/s) associated with reduced dilatancy and micro-earthquakes. Most aseismic slip occurs within the fluid-pressurized zone and obeys a rate-strengthening friction law ? = 0.67 + 0.045ln(v/v?) with v? = 0.1 ?m/s. Fluid injection primarily triggers aseismic slip in this experiment, with micro-earthquakes being an indirect effect mediated by aseismic creep. PMID:26068845

  13. Geodetic estimate of coseismic slip during the 1989 Loma Prieta, California, earthquake

    SciTech Connect

    Lisowski, M.; Prescott, W.H.; Savage, J.C.; Johnston, M.J. )

    1990-08-01

    Offsets in the relative positions of geodetic stations resulting from the Loma Prieta earthquake can be explained with a dislocation model that includes buried oblique slip on a rupture surface extending 37 km along the strike of the San Andreas fault, dipping 70{degree} to the SW, and extending from a depth of about 5 to 17.5 km. Assuming uniform slip on a rectangular surface, the mean values for a range of reasonable fault geometries are 1.6{plus minus}0.3 m right-lateral strike slip and 1.2{plus minus}0.3 m reverse slip. Slip on an adjacent extension of the rupture to the southeast, recorded in the aftershock sequence, is not well constrained by the geodetic data. The geodetic data clearly preclude rupture extending near the surface.

  14. Slip-pulse rupture behavior on a 2 m granite fault

    NASA Astrophysics Data System (ADS)

    McLaskey, Gregory C.; Kilgore, Brian D.; Beeler, Nicholas M.

    2015-09-01

    We describe observations of dynamic rupture events that spontaneously arise on meter-scale laboratory earthquake experiments. While low-frequency slip of the granite sample occurs in a relatively uniform and crack-like manner, instruments capable of detecting high-frequency motions show that some parts of the fault slip abruptly (velocity > 100 mm s-1, acceleration > 20 km s-2) while the majority of the fault slips more slowly. Abruptly slipping regions propagate along the fault at nearly the shear wave speed. We propose that the dramatic reduction in frictional strength implied by this pulse-like rupture behavior has a common mechanism to the weakening reported in high-velocity friction experiments performed on rotary machines. The slip pulses can also be identified as migrating sources of high-frequency seismic waves. As observations from large earthquakes show similar propagating high-frequency sources, the pulses described here may have relevance to the mechanics of larger earthquakes.

  15. Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere earth models

    USGS Publications Warehouse

    Savage, J.C.

    1990-01-01

    By virtue of the images used in the dislocation solution, the deformation at the free surface produced throughout the earthquake cycle by slippage on a long strike-slip fault in an Earth model consisting of an elastic plate (lithosphere) overlying a viscoelastic half-space (asthenosphere) can be duplicated by prescribed slip on a vertical fault embedded in an elastic half-space. Inversion of 1973-1988 geodetic measurements of deformation across the segment of the San Andreas fault in the Transverse Ranges north of Los Angeles for the half-space equivalent slip distribution suggests no significant slip on the fault above 30 km and a uniform slip rate of 36 mm/yr below 30 km. One equivalent lithosphere-asthenosphere model would have a 30-km thick lithosphere and an asthenosphere relaxation time greater than 33 years, but other models are possible. -from Author

  16. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation.

    PubMed

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-01-01

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm. PMID:26437412

  17. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation

    PubMed Central

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-01-01

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm. PMID:26437412

  18. Near-fault measurement of postseismic slip associated with the 1989 Loma Prieta, California, earthquake

    SciTech Connect

    Rymer, M.J. )

    1990-09-01

    Five small-aperture (0.5 to 7.7 m) quadrilaterals were installed across the San Andreas fault and newly formed extensional cracks shortly after the October 17, 1989 Loma Prieta M7.1 earthquake. Two quadrilaterals were installed across the San Andreas fault near the southeast and northwest ends of the 1989 rupture, and three were installed across dominantly extensional cracks in the Summit Road area near the main-shock epicenter and off the San Andreas fault. Measurements of line-length changes from as early as 4 d up to 184 d after the earthquake in the nail quadrilaterals indicate a small amount of right-lateral postseismic slip on the San Andreas fault. The site near the southeast end of the 1989 aftershock zone on the San Andreas fault showed about 5{plus minus}2 mm of postseismic right-lateral component of slip in addition to 23 mm of right-lateral coseismic movement. The site near the northwest end of aftershocks likewise showed about 5{plus minus}2 mm of postseismic slip, but after only 5 mm of coseismic slip. Measurements at sites across extensional cracks indicate possible minor left-lateral postseismic slips, and possible extensional/contractional motion. No measurements were made of possible vertical movements. Sites on extensional cracks showed similarly small amounts of possible postseismic lateral slip, from {approximately}2 to 10 mm, even though coseismic lateral slips were much greater (up to 410 mm) than on the surface trace of the San Andreas fault. The small slip values, in spite of uncertainties, clearly show that the lack of coseismic surface slip associated with the earthquake was not followed by large postseismic slip.

  19. Equine hoof slip distance during trot at training speed: comparison between kinematic and accelerometric measurement techniques.

    PubMed

    Holden-Douilly, Laurène; Pourcelot, Philippe; Desquilbet, Loïc; Falala, Sylvain; Crevier-Denoix, Nathalie; Chateau, Henry

    2013-08-01

    Longitudinal sliding of horse's hooves at the beginning of stance can affect both performance and orthopaedic health. The objective of this study was to compare two measurement methods for quantifying hoof slip distances at training trot. The right front hoof of four French Trotters was equipped with an accelerometer (10 kHz) and kinematic markers. A firm wet sand track was equipped with a 50 m calibration corridor. A high-frequency camera (600 Hz) was mounted in a vehicle following each horse trotting at about 7 m/s. One of the horses was also trotted on raw dirt and harrowed dirt tracks. Longitudinal slip distance was calculated both from kinematic data, applying 2D direct linear transformation (2D-DLT) to the markers image coordinates, and from the double integration of the accelerometer signal. For each stride, both values were compared. The angle of the hoof with respect to the track was also measured. There was 'middling/satisfactory' agreement between accelerometric and 2D-DLT measurements for total slip and 'fairly good' agreement for hoof-flat slip. The influence of hoof rotation on total slip distance represented <6% of accelerometric measures. The differences between accelerometric and kinematic measures (from -0.5 cm to 2.1cm for total slip and from -0.2 cm to 1.4 cm for hoof-flat slip) were independent of slip distance magnitude. The accelerometric method was a simple method to measure hoof slip distances at a moderate training speed trot which may be useful to compare slip distances on various track surfaces. PMID:23489849

  20. Dynamic Weakening by Acoustic Fluidization during Stick-Slip Motion.

    PubMed

    Giacco, F; Saggese, L; de Arcangelis, L; Lippiello, E; Pica Ciamarra, M

    2015-09-18

    The unexpected weakness of some faults has been attributed to the emergence of acoustic waves that promote failure by reducing the confining pressure through a mechanism known as acoustic fluidization, also proposed to explain earthquake remote triggering. Here we validate this mechanism via the numerical investigation of a granular fault model system. We find that the stick-slip dynamics is affected only by perturbations applied at a characteristic frequency corresponding to oscillations normal to the fault, leading to gradual dynamical weakening as failure is approaching. Acoustic waves at the same frequency spontaneously emerge at the onset of failure in the absence of perturbations, supporting the relevance of acoustic fluidization in earthquake triggering. PMID:26431017

  1. Nanobubbles and their role in slip and drag.

    PubMed

    Maali, Abdelhamid; Bhushan, Bharat

    2013-05-01

    Atomic force microscope images of flat solid surfaces in water reveal that very soft objects can be formed on the surfaces. These objects are nanobubbles of gas with sizes ranging from 10 nm to several micrometers. The bubbles are stable to dissolution, lasting for several hours. In this paper we review some of the methods that allow their generation and observation using the atomic force microscope. Next, we describe the influence of the bubbles on liquid slip close to a hydrophobic surface. The influence of liquid-gas menisci, formed as a result of nanobubbles being present on the surface, on drag reduction is also discussed. Finally, data of liquid flow probed on bubbles entrapped on microstructured surfaces are presented. PMID:23598711

  2. Hydrogen generation along simulated faults at coseismic slip conditions

    NASA Astrophysics Data System (ADS)

    Hirose, T.; Suzuki, K.

    2009-12-01

    Since the discovery of deep-sea hydrothermal vents in the late 1970s, the most ancient microbial ecosystems are considered to evolve at habitable environments in the vicinity of H2-rich hydrothermal fluids (e.g., Russell & Hall, 1997). In the modern ocean, the H2-rich hydrothermal fluids that are often observed along the slow-spreading Mid Ocean Ridges (MOR) are most likely to be provided by the ultramafic rock-water reaction (serpentinization) (e.g., Seyfried et al., 1979). However, such H2-rich fluids can be also found at the East Pacific Rise (EPR) where ultramafic rocks are not exposed. In this study, we hypothesized that the H2-rich fluids at the EPR are produced during the seismic events in basaltic rocks, and that the H2 generation associated with seismic faulting could contribute to sustaining the subsurface biological communities. In order to confirm above hypotheses, we performed laboratory friction experiments on gabbro, dunite and granite at a constant normal stress of 1.0 MPa, slip velocities, V, of 0.09~1.6 m/s (nearly coseismic slip rates) and displacements of more than 10 m using a rotary-shear apparatus. Slip on the simulated fault was conducted within a small pressure vessel that was filled with air. H2 gas released during experiments was measured by a micro gas chromatograph which was directly connected to the pressure vessel. The main findings of our preliminary experimental work are: (1) H2 gas could not be detected at V < 0.09 m/s, while it was detected and increased with slip velocities over 0.3 m/s for all rock types. The amount of H2 generation in granite samples at 0.6 m/s is more than 20 times higher than that of dunite and gabbro. (2) When a few drops of distilled water were added to the sliding surfaces, the H2 production was enhanced for all rock types. (3) When the wet dunite specimen was sheared at V of 1.3 m/s corresponding to a total mechanical work energy of ~4.5 kJ (calculated as shear stress multiplied by displacement), the H2 concentration is about 5 milimoles per kilogram of fine-grained gouge formed by frictional sliding. Our experimental results are consistent with the previous experimental studies of H2 generation by rock crushing using a ball mill (e.g., Kita et al., 1982; Kameda et al., 2003). Our results also suggest that the H2 gas released during our experiments could be sourced from a chemical reaction between water (or moisture) and free radicals (Si’ and Si-O’) formed by the break of Si-O-Si bonds during high velocity sliding. In terms of earthquake energy, the total work energy of several kJ applied on the sliding surfaces in our experiments corresponds to an earthquake magnitude of less than one. Enormous number of such small earthquakes currently occurs along the MORs. Although further careful consideration is needed to evaluate the contribution of earthquake related H2 generation to the microbial ecosystems, our results imply that H2 generation due to seismic faulting may possibly affect the evolution of subsurface microbes.

  3. Study of nanocrystals in the dynamic slip zone

    NASA Astrophysics Data System (ADS)

    Sobolev, G. A.; Kireenkova, S. M.; Morozov, Yu. A.; Smul'skaya, A. I.; Vettegren, V. I.; Kulik, V. B.; Mamalimov, R. I.

    2012-09-01

    Mineral composition is studied and a search to detect nanocrystals is conducted in the surface layers of slickensides formed due to dynamic slip in arkose sandstone. The infrared and Raman spectroscopy show that the slickensided layer is composed of nanocrystals of montmorillonite and anatase measuring ?15 nm and 3 nm, respectively. The crystalline lattice of the nanocrystals of montmorillonite is stretched by ?2.5% while the lattice of the nanocrystals of anatase is compressed by ?0.12%. Deeper than 3 mm below the slickenside surface, the sandstone contains nanocrystals of montmorillonite, beidellite and nontronite, quartz, plagioclase, and anatase. The nanocrystals of anatase have a linear size of ?8 nm. Their crystalline lattice is compressed by ?0.03%. It is supposed that montmorillonite in the slickensides was formed due to hydrolytic decomposition of silicates under friction of the fault planes sliding past each other.

  4. Heat transfer from cylinders in subsonic slip flows

    NASA Technical Reports Server (NTRS)

    Nagabushana, K. A.; Stainback, P. C.

    1992-01-01

    The heat transfer in heated wires was measured using a constant temperature anemometer over a Mach number range from 0.05 to 0.4 and pressures from 0.5 to 8.0 atmospheres. The total temperature ranged from 80 to 120 F and the wire diameters were 0.00015, 0.00032, and 0.00050 inch. The heat transfer data is presented in the form of a corrected Nusselt number. Based on suggested criteria, much of the data was obtained in the slip flow regime. Therefore, the data is compared with data having comparable flow conditions. The possible application of the heat transfer data to hot wire anemometry is discussed. To this end, the sensitivity of the wires to velocity, density, and total temperature is computed and compared using two different types of correlations.

  5. Modeling of ductile deformation in anisotropic rocks with slip surfaces

    NASA Astrophysics Data System (ADS)

    Dabrowski, Marcin

    2013-04-01

    Flanking structures and sheath folds can develop in layered rocks due to flow perturbation around slip surfaces in shear zones (Exner and Dabrowski, 2010; Reber et al., submitted). Mechanical anisotropy of the host rock has been shown to play a major role in determining the slip rate and the flow pattern around it (Kocher and Mancktelow, 2006; Fletcher, 2011). In addition, anisotropic fluids such as ductile foliated rocks have a 'memory' of deformation due to evolving microstructure. For example, the rotation of a rigid circular inclusion embedded in a layered host in layer-parallel shear results in the structural reorganization around it, which leads to the modification of the flow pattern in the host and in consequence to a massive reduction of the inclusion rotation rate (Dabrowski and Schmid, 2011). Willis (1964) derived an analytical elastic solution for an elliptical inclusion in a homogeneous anisotropic matrix subject to a uniform load in the far field. The solution can be reduced to the case of an incompressible viscous medium. The case of an arbitrarily oriented inviscid slit under shear parallel to the principal axis of anisotropy can be obtained by reducing it even further. Although derived for the initial state of homogeneous planar anisotropy, the solution provides useful insights into the large deformation behavior of the system. In this study, I will use different models and numerical modeling techniques to assess the impact of mechanical anisotropy and structural development on the perturbing flow around an inviscid slit (slip surface) embedded in a host comprising discrete isotropic layers in layer-parallel simple shear. In the limit of thin layers (the number of layers intercepting the slit tends to infinity), the host is modeled as an anisotropic fluid. The anisotropic viscosity is determined by the bulk anisotropic viscosity of the layered system. The layering is initially planar or equivalently the anisotropy is initially homogeneous. Both non-planar layering and variable orientations of the principal axis of the anisotropy develop around the slit with large deformation. References: Dabrowski, M. and Schmid, D.W., 2011: A rigid circular inclusion in an anisotropic host subject to simple shear, Journal of Structural Geology 33, 1169-1177 Exner, U., Dabrowski, M., 2010: Monoclinic and triclinic 3D flanking structures around elliptical cracks, Journal of Structural Geology 32, 2009-2021 Fletcher, R.C, 2011: Deformable, rigid, and inviscid elliptical inclusions in a homogeneous incompressible anisotropic viscous fluid, Journal of Structural Geology 31, 382-387 Kocher, T., Mancktelow, N.S, 2006: Flanking structure development in anisotropic viscous rock, Journal of Structural Geology 28, 1139-1145 Reber, J. E., Dabrowski, M & Schmid, D. W., 2012: Sheath fold formation around slip surfaces. Terra Nova. 24(5), 417- 421 Willis, J.R., 1964: Anisotropic elastic inclusion problems, Quarterly Journal of Mechanics and Applied Mathematics 17, p.157.

  6. Aqueous slip casting of stabilized AlN powders

    SciTech Connect

    Groat, E.A.; Mroz, T.J. )

    1994-11-01

    Because of the interest in aluminum nitride (AlN) for various refractory and structural applications, methods are required to cost-effectively process a water-sensitive material into the required shapes. The existence of water-resistant AlN powders has allowed the consideration of aqueous processing of a material that previously required solvent-based formulation. The composition and procedures developed for aqueous slip-casting water-resistant AlN powders provide a manufacturing route for the fabrication of large and complex geometries. Technology to create aqueous dispersions of these powders also potentially enables other manufacturing processes, such as extrusion and spray drying, to utilize the cost advantages of aqueous processing.

  7. Collective Quantum Phase-Slip Dynamics in Superconducting Nanowire Arrays

    NASA Astrophysics Data System (ADS)

    Skacel, Sebastian T.; Voss, Jan N.; Bier, Tobias; Radke, Lucas; Weides, Martin; Rotzinger, Hannes; Mooij, Hans E.; Ustinov, Alexey V.

    2014-03-01

    Superconducting nanowire arrays exhibit quantum phase-slip (QPS) phenomenon if the superconductor has a very high normal-state sheet resistance. We experimentally study QPS effects in arrays of nanowires embedded in a resonant circuit at GHz frequencies. We probe this circuit at ultra-low microwave power, applied flux and mK temperatures. The nanowires are fabricated utilizing aluminium grown in a precisely-controlled oxygen atmosphere. In this way, we aim to control the QPS rate for a given wire width. The wires are defined with conventional electron beam lithography down to a width of 20 nm. We will present the fabrication of the nanowire arrays and first microwave measurements at mK temperatures. Center for Functional Nanostructures, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany.

  8. Water accumulation below Europa's strike-slip faults

    NASA Astrophysics Data System (ADS)

    Kalousova, K.; Tobie, G.; Soucek, O.; Choblet, G.; Cadek, O.

    2015-10-01

    The onset of melting below Europa's recently active strike-slip faults and the gravitational/thermal stability of partially molten ice are investigated by solving the equations for a two-phase compressible mixture of water ice and liquid water in 2D geometry. As a first step, the relative motion between ice and water is neglected, i.e. the meltwater is transported by the flowing ice. Our preliminary results suggest that for sufficiently large shear heating rate of˜2×10?4W m?3 melting can occur at depths as shallow as˜3km below Europa's surface. Moreover, the reservoirs of partially molten ice with˜5-10% of liquid water can remain within the cold lid for a few hundreds of kiloyears if the underlying ice is sufficiently cold (vis-cous) and free of fractures.

  9. Can fault slip affect vitrinite reflectance without heat?

    NASA Astrophysics Data System (ADS)

    Fulton, P. M.; Kitamura, M.; Mukoyoshi, H.; Hirose, T.

    2012-12-01

    Vitrinite reflectance, R, is a measure of the thermal maturation of coal and has become a tantalizing method for inferring the effects of frictional heating within fault zones. Recent studies, however, suggest the method as commonly applied overpredicts peak fault zone temperatures [Kitamura et al., 2012; Fulton and Harris, 2012]. One unaddressed question in interpreting fault zone vitrinite reflectance data in terms of frictional heating and earthquake and tsunami hazard is whether fault slip can increase R values without significant frictional heating. Here we evaluate the non-thermal effects of fault slip on R values through laboratory friction experiments on saturated simulated gouge mixtures of 90% bentonite clay and 10% vitrinite-rich coal. The coal material, San Miguel Lignite mined from Christine, TX, has a very low starting vitrinite reflectance of Rmax = 0.20 ± 0.03% such that it is highly susceptible and sensitive to changes in maturation. The experiments are run under anoxic conditions at 1 MPa normal stress. Two series of experiments are conducted: one in which several experiments are run with the same total displacement of 3 or 10 m and differ in their average displacement rate ranging from 1.3 to 1307 mm/s, and another series of experiments with the same displacement rate of 1.3 mm/s and with differing total displacements ranging from 0.3 to 10 m. In all experiments temperatures measured at the edge of the gouge zone do not increase by more than 15 oC during the experiment, which is hundreds of degrees less than what is expected to have any thermal effect on the reflectance. Using an oil-immersion microscope with a microspot lighting system (spot size 1.6 ?m), both the maximum and minimum reflectance, Rmax and Rmin, was measured on all vitrinite grains larger than ~ 5?m within thin sections cut orthogonal to both the slip direction and sample gouge layer. Analysis of the results suggests the possibility of a very subtle increase of <0.05% with increased displacement. However, this very small increase is within the standard deviation amongst measurements and is not likely significant. In addition, the spatial distribution of Rmax, Rmin, and anisotropy values all appear randomly distributed within the thin sections and do not appear concentrated in zones of strain localization. Our results suggest that, at least for clay dominated gouge zones, there is essentially no non-thermal effect on vitrinite reflectance under a reasonable range of slip rates and displacements typical of earthquakes and for conditions likely applicable for the shallow toe of subduction zones where IODP fault zone cores have recently been obtained (e.g., Nankai and Japan Trench). Observations of increases in R in such locations would thus likely reflect the effects of frictional heating, although how the mechanical effects of shearing combined with fast heating may affect the kinetics requires further evaluation in order to accurately assess peak temperature values.

  10. Johnson & Goodman Jointly Poisson Processes Jointly Poisson processes

    E-print Network

    Johnson & Goodman Jointly Poisson Processes Jointly Poisson processes Don H. Johnson and Ilan N. Goodman Electrical & Computer Engineering Department, MS380 Rice University Houston, Texas 77005­1892 {dhj for Gaussian 1 November 12, 2009 #12;Johnson & Goodman Jointly Poisson Processes random variables. A set

  11. Report on the Aseismic Slip, Tremor, and Earthquakes Workshop

    USGS Publications Warehouse

    Gomberg, Joan; Roeloffs, Evelyn; Trehu, Anne; Dragert, Herb; Meertens, Charles

    2008-01-01

    This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities presented by these phenomena. Research activities of focus included making, disseminating, and analyzing relevant measurements; the relationships among tremor, aseismic or 'slow-slip', and earthquakes; and discovering the underlying causative physical processes. More than 52 participants contributed to the workshop, held February 25-28, 2008 in Sidney, British Columbia. The workshop was sponsored by the U.S. Geological Survey, the National Science Foundation?s Earthscope Program and UNAVCO Consortium, and the Geological Survey of Canada. This report has five parts. In the first part, we integrate the information exchanged at the workshop as it relates to advancing our understanding of earthquake generation and hazard. In the second part, we summarize the ideas and concerns discussed in workshop working groups on Opportunities for Education and Outreach, Data and Instrumentation, User and Public Needs, and Research Coordination. The third part presents summaries of the oral presentations. The oral presentations are grouped as they were at the workshop in the categories of phenomenology, underlying physical processes, and implications for earthquake hazards. The fourth part contains the meeting program and the fifth part lists the workshop participants. References noted in parentheses refer to the authors of presentations made at the workshop, and published references are noted in square brackets and listed in the Reference section. Appendix A contains abstracts of all participant presentations and posters, which also have been posted online, along with presentations and author contact information at http://www.earthscope.org/science/cascadia.

  12. Concentration polarization and nonequilibrium electroosmotic slip in dense multiparticle systems.

    PubMed

    Nischang, Ivo; Reichl, Udo; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

    2007-08-28

    Electrical field-induced concentration polarization (CP) and CP-based nonequilibrium electroosmotic slip are studied in fixed beds of strong cation-exchange particles using confocal laser scanning microscopy (CLSM) and the macroscopic electroosmotic flow (EOF) dynamics. A key property of the investigated fixed beds is the coexistence of quasi-electroneutral macroporous regions between the micrometer-sized particles and the ion-permselective (here, cation-selective) intraparticle mesopores with a mean size of 10 nm. The application of an external electrical field to the particles induces depleted and enriched CP zones along their anodic and cathodic interfaces, respectively, by the local interplay of diffusive and electrokinetic transport. The intensity and dimension of the CP zones depend on the applied electrical field strength and the fluid-phase ionic strength. With increasing field strength a limiting current density through a particle is approached, meaning that charge transport locally through a particle becomes controlled by the dynamics in the adjoining extraparticle convective-diffusion boundary layer (depleted CP zone). In this regime a nonequilibrium electrical double layer can be induced electrokinetically in the depleted CP zone and intraparticle pore space, resulting in nonlinear EOF in the interparticle macropore space. The local CP dynamics analyzed by CLSM is successfully correlated with the onset of nonlinearity in the macroscopic EOF dynamics. We further demonstrate that multiparticle effects arising in fixed beds (random close packings) of ion-permselective particles modulate significantly the local pattern of CP and intensity of the nonequilibrium electroosmotic slip with respect to the undisturbed single-particle picture. PMID:17683148

  13. Clad metal joint closure

    SciTech Connect

    Siebert, O.W.

    1985-04-09

    A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.

  14. Temporomandibular joint dislocation

    PubMed Central

    Sharma, Naresh Kumar; Singh, Akhilesh Kumar; Pandey, Arun; Verma, Vishal; Singh, Shreya

    2015-01-01

    Temporomandibular joint (TMJ) dislocation is an uncommon but debilitating condition of the facial skeleton. The condition may be acute or chronic. Acute TMJ dislocation is common in clinical practice and can be managed easily with manual reduction. Chronic recurrent TMJ dislocation is a challenging situation to manage. In this article, we discuss the comprehensive review of the different treatment modalities in managing TMJ dislocation.

  15. Realignment Subtalar Joint Arthrodesis.

    PubMed

    Hentges, Matthew J; Gesheff, Martin G; Lamm, Bradley M

    2016-01-01

    Subtalar joint arthrodesis is a commonly performed procedure for the correction of hindfoot deformity and/or the relief of pain related to osteoarthritis. The purpose of the present study was to provide preoperative and intraoperative objective radiographic parameters to improve the accuracy and long-term success of realignment arthrodesis of the subtalar joint. We retrospectively reviewed the data from 16 patients, 11 male (57.9%) and 8 female (42.1%) feet, who had undergone realignment subtalar joint arthrodesis. A total of 19 fusions were performed in 9 (47.4%) right and 10 (52.6%) left feet, with a mean follow-up period of 2 (range 1 to 4.8) years. The mean age at surgery was 54.5 (range 14 to 77) years. Statistically significant improvement in radiographic alignment was found in the anteroposterior talo-first metatarsal angle (p = .002), lateral talo-first metatarsal angle (p < .001), tibial-calcaneal angle (p < .001), and tibial-calcaneal distance (p < .001). A positive correlation was observed between the tibial-calcaneal angle and tibial-calcaneal distance (r = 0.825, p < .001). The statistically significant improvement in tibial-calcaneal alignment, in both angulation and distance, support our conclusions that proper realignment of the calcaneus to vertical and central under the tibia will lead to short-term success and, likely, long-term success of subtalar joint arthrodesis. PMID:26028600

  16. Shoulder Joint For Protective Suit

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Smallcombe, Richard D.

    1994-01-01

    Shoulder joint allows full range of natural motion: wearer senses little or no resisting force or torque. Developed for space suit, joint offers advantages in protective garments for underwater work, firefighting, or cleanup of hazardous materials.

  17. Joint Institute Marine and Atmospheric

    E-print Network

    Hawai'i at Manoa, University of

    Joint Institute for Marine and Atmospheric Research NATIONALOCEA NIC AND ATMOSPHERIC ADMINISTRATION Contribution 00-328 #12;ii This research is funded by Cooperative Agreement Number NA67RJ0154 between the Joint

  18. Rolling contact orthopaedic joint design

    E-print Network

    Slocum, Alexander Henry, Jr

    2013-01-01

    Arthroplasty, the practice of rebuilding diseased biological joints using engineering materials, is often used to treat severe arthritis of the knee and hip. Prosthetic joints have been created in a "biomimetic" manner to ...

  19. Anaerobic prosthetic joint infection.

    PubMed

    Shah, Neel B; Tande, Aaron J; Patel, Robin; Berbari, Elie F

    2015-12-01

    In an effort to improve mobility and alleviate pain from degenerative and connective tissue joint disease, an increasing number of individuals are undergoing prosthetic joint replacement in the United States. Joint replacement is a highly effective intervention, resulting in improved quality of life and increased independence [1]. By 2030, it is predicted that approximately 4 million total hip and knee arthroplasties will be performed yearly in the United States [2]. One of the major complications associated with this procedure is prosthetic joint infection (PJI), occurring at a rate of 1-2% [3-7]. In 2011, the Musculoskeletal Infectious Society created a unifying definition for prosthetic joint infection [8]. The following year, the Infectious Disease Society of America published practice guidelines that focused on the diagnosis and management of PJI. These guidelines focused on the management of commonly encountered organisms associated with PJI, including staphylococci, streptococci and select aerobic Gram-negative bacteria. However, with the exception of Propionibacterium acnes, management of other anaerobic organisms was not addressed in these guidelines [1]. Although making up approximately 3-6% of PJI [9,10], anaerobic microorganisms cause devastating complications, and similar to the more common organisms associated with PJI, these bacteria also result in significant morbidity, poor outcomes and increased health-care costs. Data on diagnosis and management of anaerobic PJI is mostly derived from case reports, along with a few cohort studies [3]. There is a paucity of published data outlining factors associated with risks, diagnosis and management of anaerobic PJI. We therefore reviewed available literature on anaerobic PJI by systematically searching the PubMed database, and collected data from secondary searches to determine information on pathogenesis, demographic data, clinical features, diagnosis and management. We focused our search on five commonly encountered anaerobic organisms associated with PJI. Since anaerobic PJI has also been linked to dental procedures, we also reviewed information on the use of dental procedures and prophylaxis, when available. PMID:26341272

  20. Cellular Pressure-Actuated Joint

    NASA Technical Reports Server (NTRS)

    McGuire, John R.

    2003-01-01

    A modification of a pressure-actuated joint has been proposed to improve its pressure actuation in such a manner as to reduce the potential for leakage of the pressurizing fluid. The specific joint for which the modification is proposed is a field joint in a reusable solid-fuel rocket motor (RSRM), in which the pressurizing fluid is a mixture of hot combustion gases. The proposed modification could also be applicable to other pressure-actuated joints of similar configuration.

  1. Determination of Parachute Joint Factors using Seam and Joint Testing

    NASA Technical Reports Server (NTRS)

    Mollmann, Catherine

    2015-01-01

    This paper details the methodology for determining the joint factor for all parachute components. This method has been successfully implemented on the Capsule Parachute Assembly System (CPAS) for the NASA Orion crew module for use in determining the margin of safety for each component under peak loads. Also discussed are concepts behind the joint factor and what drives the loss of material strength at joints. The joint factor is defined as a "loss in joint strength...relative to the basic material strength" that occurs when "textiles are connected to each other or to metals." During the CPAS engineering development phase, a conservative joint factor of 0.80 was assumed for each parachute component. In order to refine this factor and eliminate excess conservatism, a seam and joint testing program was implemented as part of the structural validation. This method split each of the parachute structural joints into discrete tensile tests designed to duplicate the loading of each joint. Breaking strength data collected from destructive pull testing was then used to calculate the joint factor in the form of an efficiency. Joint efficiency is the percentage of the base material strength that remains after degradation due to sewing or interaction with other components; it is used interchangeably with joint factor in this paper. Parachute materials vary in type-mainly cord, tape, webbing, and cloth -which require different test fixtures and joint sample construction methods. This paper defines guidelines for designing and testing samples based on materials and test goals. Using the test methodology and analysis approach detailed in this paper, the minimum joint factor for each parachute component can be formulated. The joint factors can then be used to calculate the design factor and margin of safety for that component, a critical part of the design verification process.

  2. High resolution 3D laser scanner measurements of a strike-slip fault quantify its morphological anisotropy at all scales

    E-print Network

    Schmittbuhl, Jean

    High resolution 3D laser scanner measurements of a strike-slip fault quantify its morphological, and J. Schmittbuhl (2006), High resolution 3D laser scanner measurements of a strike-slip fault quantify] The surface roughness of a recently exhumed strike- slip fault plane has been measured by three independent 3D

  3. Coseismic slip variation assessed from terrestrial lidar scans of the El Mayor-Cucapah surface rupture

    NASA Astrophysics Data System (ADS)

    Gold, Peter O.; Oskin, Michael E.; Elliott, Austin J.; Hinojosa-Corona, Alejandro; Taylor, Michael H.; Kreylos, Oliver; Cowgill, Eric

    2013-03-01

    We analyze high-resolution (>103 points/m2) terrestrial lidar surveys of the 4 April 2010 El Mayor-Cucapah earthquake rupture (Baja California, Mexico), collected at three sites 12-18 days after the event. Using point cloud-based tools in an immersive visualization environment, we quantify coseismic fault slip for hundreds of meters along strike and construct densely constrained along-strike slip distributions from measurements of offset landforms. Uncertainty bounds for each offset, determined empirically by repeatedly measuring offsets at each site sequentially, illuminate measurement uncertainties that are difficult to quantify in the field. These uncertainties are used to define length scales over which variability in slip distributions may be assumed to reflect either recognizable earthquake mechanisms or measurement noise. At two sites characterized by 2-3 m of concentrated right-oblique slip, repeat measurements yield 2? uncertainties of ±11-12%. Each site encompasses ?200 m along strike, and a smoothed linear slip gradient satisfies all measurement distributions, implying along-fault strains of ?10-3. Conversely, the common practice of defining the slip curve by the local slip maxima distorts the curve, overestimates along-fault strain, and may overestimate actual fault slip by favoring measurements with large, positive, uncertainties. At a third site characterized by 1-2.5 m of diffuse normal slip, repeat measurements of fault throw summed along fault-perpendicular profiles yield 2? uncertainties of ±17%. Here, a low order polynomial fit through the measurement averages best approximates surface slip. However independent measurements of off-fault strain accommodated by hanging wall flexure suggest that over the ?200 m length of this site, a linear interpolation through the average values for the slip maxima at either end of this site most accurately represents subsurface displacement. In aggregate, these datasets show that given uncertainties of greater than ±11% (2?), slip distributions over shorter scales are likely to be less uneven than those derived from a single set of field- or lidar-based measurements. This suggests that the relatively smooth slip curves we obtain over ?102 m distances reflect real physical phenomena, whereas short wavelength variability over ?100-101 m distances can be attributed to measurement uncertainty.

  4. Evidence for and implications of self-healing pulses of slip in earthquake rupture

    USGS Publications Warehouse

    Heaton, T.H.

    1990-01-01

    Dislocation time histories of models derived from waveforms of seven earthquakes are discussed. In each model, dislocation rise times (the duration of slip for a given point on the fault) are found to be short compared to the overall duration of the earthquake (??? 10%). However, in many crack-like numerical models of dynamic rupture, the slip duration at a given point is comparable to the overall duration of the rupture; i.e. slip at a given point continues until information is received that the rupture has stopped propagating. Alternative explanations for the discrepancy between the short slip durations used to model waveforms and the long slip durations inferred from dynamic crack models are: (1) the dislocation models are unable to resolve the relatively slow parts of earthquake slip and have seriously underestimated the dislocations for these earthquakes; (2) earthquakes are composed of a sequence of small-dimension (short duration) events that are separated by locked regions (barriers); (3) rupture occurs in a narrow self-healing pulse of slip that travels along the fault surface. Evidence is discussed that suggests that slip durations are indeed short and that the self-healing slip-pulse model is the most appropriate explanation. A qualitative model is presented that produces self-healing slip pulses. The key feature of the model is the assumption that friction on the fault surface is inversely related to the local slip velocity. The model has the following features: high static strength of materials (kilobar range), low static stress drops (in the range of tens of bars), and relatively low frictional stress during slip (less than several hundreds of bars). It is suggested that the reason that the average dislocation scales with fault length is because large-amplitude slip pulses are difficult to stop and hence tend to propagate large distances. This model may explain why seismicity and ambient stress are low along fault segments that have experienced large earthquakes. It also qualitatively explains why the recurrence time for large earthquakes may be irregular. ?? 1990.

  5. Double slotted socket spherical joint

    DOEpatents

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

    2001-05-22

    A new class of spherical joints is disclosed. These spherical joints are capable of extremely large angular displacements (full cone angles in excess of 270.degree.), while exhibiting no singularities or dead spots in their range of motion. These joints can improve or simplify a wide range of mechanical devices.

  6. JOINT PERFORMANCE Guide for Optimum

    E-print Network

    July 2012 JOINT PERFORMANCE Guide for Optimum of Concrete Pavements #12; #12;Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2. Report Date Guide for Optimum Joint Performance of Concrete Pavements July 2012 6. Performing

  7. Phase 1 Program Joint Report

    NASA Technical Reports Server (NTRS)

    Nield, George C. (Editor); Vorobiev, Pavel Mikhailovich (Editor)

    1999-01-01

    This report consists of inputs from each of the Phase I Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.

  8. Development of deep-seated joint sets in the different stages of mountain building: a preliminary study in the northern fold-and-thrust belt of Taiwan

    NASA Astrophysics Data System (ADS)

    Lee, Jian-Cheng; Chu, Hao-Tsu; Angelier, Jacques; Begerat, Françoise

    2013-04-01

    Systematic joint sets are one of the most common and persistent features within a brittle deformation regime, usually found in intact rocks, such as massive sandstone. However, joint occurrence can take place under different circumstances from very shallow to rather deep crust, which raise challenges for understanding the mechanisms of its development and thus provokes debates in past decades. In this study, we characterize the deformation structures, including micro fault and joint, by comparing their geometric relation with stratigraphic bedding plane. We intend not only to differentiate the relative chronology of different structures but also to determine the chronological orders and stages during thrust stacking processes in which rocks buried to certain depths and then exhumed from depths to surface. We take the northern fold-and-thrust belt of Taiwan as our case study area. The study area is composed of Pleistocene to Oligocene, terrestrial to shallow marine sedimentary deposits, which was exhumed accompanied with a series of imbricate thrusts during the Plio-Pleistocene orogeny of arc-continent collision between the Philippine Sea and Eurasian plates. We study four cross sections from little deformed rock formations in the foreland to intense folded and even slightly metamorphosed terrains in the slate belt, in order to characterize and distinguish different brittle structures at different depths. Particular attention is paid to the development of the joint sets at different depths and their relationship with the bedding plane and other associated deformation features where joints happen to occur. We found that 1) the most predominant joint sets are deep-seated and tectonics related, in comparison with shallow released joints, although their relation with tectonic stress orientation remains inconclusive; 2) the onset depths of development of joint sets can be as shallow as 3-4 km and as deep as 10-15 km. As to whether the development occurs during burial or exhumation, it remains questionable; 3) micro faults with striated slip, mainly under NW-directed compression induced by indentation of the Philippine Sea plate, occur exclusively after formation of persistent joint sets and often during thrust stacking or folding; 4) joint sets often serve as the guiding slip planes for a large portion of strike-slip micro faulting. In contrast, many thrust micro faults use bedding planes for their slip planes, especially during stacking and folding processes.

  9. Slow slip pulses driven by thermal pressurization of pore fluid: theory and observational constraints

    NASA Astrophysics Data System (ADS)

    Garagash, D.

    2012-12-01

    We discuss recently developed solutions for steadily propagating self-healing slip pulses driven by thermal pressurization (TP) of pore fluid [Garagash, 2012] on a fault with a constant sliding friction. These pulses are characterized by initial stage of undrained weakening of the fault (when fluid/heat can not yet escape the frictionally heated shear zone), which gives way to partial restrengthening due to increasing hydrothermal diffusion under conditions of diminished rate of heating, leading to eventual locking of the slip. The rupture speed of these pulses is decreasing function of the thickness (h) of the principal shear zone. We find that "thick" shear zones, h >> hdyna, where hdyna = (?/?0) (?c/f?)(4?/cs), can support aseismic TP pulses propagating at a fraction hdyna/h of the shear wave speed cs, while "thin" shear zones, h˜hdyna or thinner, can only harbor seismic slip. (Here ? - shear modulus, ?0 - the nominal fault strength, f - sliding friction, ?c - the heat capacity of the fault gouge, ? - the fluid thermal pressurization factor, ? - hydrothermal diffusivity parameter of the gouge). For plausible range of fault parameters, hdyna is between 10s to 100s of micrometers, suggesting that slow slip transients propagating at 1 to 10 km/day may occur in the form of a TP slip pulse accommodated by a meter-thick shear zone. We verify that this is, indeed, a possibility by contrasting the predictions for aseismic, small-slip TP pulses operating at seismologically-constrained, near-lithostatic pore pressure (effective normal stress ? 3 to 10 MPa) with the observations (slip duration at a given fault location ? week, propagation speed ? 15 km/day, and the inferred total slip ? 2 to 3 cm) for along-strike propagation of the North Cascadia slow slip events of '98-99 [Dragert et al., 2001, 2004]. Furthermore, we show that the effect of thermal pressurization on the strength of the subduction interface is comparable to or exceeds that of the rate-dependence of friction, previously suggested as a mechanism for aseismic transients [e.g., Liu and Rice, 2009; Segall et al., 2010], if the frictional properties of gabbro [He et al., 2007] under the hydrothermal conditions for the North Cascadia slab [Hacker et al., 2003] are used. It therefore appears that while some friction weakening with the slip rate may be required to nucleate a slow slip event in the first place, thermal pressurization mechanism has to be included in realistic models of dynamics of aseismic slip transients, as long as the source of the transients is linked to the conditionally-stable part of the interface (with near velocity-neutral friction). The results of this study point to the importance of the principal shear zone thickness during a slip event and its possible change with the slip rate [e.g., Platt et al., AGU FM 2010]. The insight into how stable creep or a slow slip event may transition into a seismic rupture and how an earthquake rupture "selects" its principal shear zone, which is shown to largely define the TP slip dynamics, may require addressing the slip localization as a phenomena concurrent to the development of transient slip, and therefore coupled to other relevant source mechanisms.

  10. Slip detection and grip adjustment using optical tracking in prosthetic hands.

    PubMed

    Roberts, Luke; Singhal, Girish; Kaliki, Rahul

    2011-01-01

    We have designed a closed loop control system that adjusts the grasping force of a prosthetic hand based on the amount of object slip detected by an optical tracking sensor. The system was designed for the i-Limb (a multi-fingered prosthetic hand from Touch Bionics Inc.) and is comprised of an optical sensor embedded inside a silicone prosthetic glove and a control algorithm. In a proof of concept study to demonstrate the effectiveness of optical tracking in slip sensing, we record slip rate while increasing the weight held in the grasp of the hand and compare two cases: grip adjustment on and grip adjustment off. The average slip rate was found to be 0.314 slips/(s · oz) without grip adjustment and 0.0411 slips/(s · oz) with grip adjustment. This paper discusses the advantages of the optical approach in slip detection and presents the experiment and results utilizing the optical sensor and grip control algorithm. PMID:22254954

  11. Basal slip and texture development in calcite: new results from torsion experiments

    SciTech Connect

    Barber, D. J.; Wenk, H.-R.; Gomez-Barreiro, J.; Rybacki, E.; Dresen, G.

    2008-06-09

    The deformation behavior of calcite has been of longstanding interest. Through experiments on single crystals, deformation mechanisms were established such as mechanical twinning on e = {l_brace}{bar 1}018{r_brace} <40{bar 4}1> in the positive sense and slip on r = {l_brace}10{bar 1}4{r_brace} <20{bar 2}{bar 1}> and f = {l_brace}{bar 1}012{r_brace} <0{bar 2}2{bar 1}> both in the negative sense. More recently it was observed that at higher temperatures f{l_brace}{bar 1}012{r_brace} <10{bar 1}1> slip in both senses becomes active and, based on slip line analysis, it was suggested that e(0001) <11{bar 2}0> slip may occur. So far there had been no direct evidence for basal slip, which is the dominant system in dolomite. With new torsion experiments on calcite single crystals at 900 K and transmission electron microscopy, this study identifies (0001) <11{bar 2}0> slip unambiguously by direct imaging of dislocations and diffraction contrast analysis. Including this slip system in polycrystal plasticity simulations, enigmatic texture patterns observed in compression and torsion of calcite rocks at high temperature can now be explained, resolving a long-standing puzzle.

  12. Quantification of surface charge density and its effect on boundary slip.

    PubMed

    Jing, Dalei; Bhushan, Bharat

    2013-06-11

    Reduction of fluid drag is important in the micro-/nanofluidic systems. Surface charge and boundary slip can affect the fluid drag, and surface charge is also believed to affect boundary slip. The quantification of surface charge and boundary slip at a solid-liquid interface has been widely studied, but there is a lack of understanding of the effect of surface charge on boundary slip. In this paper, the surface charge density of borosilicate glass and octadecyltrichlorosilane (OTS) surfaces immersed in saline solutions with two ionic concentrations and deionized (DI) water with different pH values and electric field values is quantified by fitting experimental atomic force microscopy (AFM) electrostatic force data using a theoretical model relating the surface charge density and electrostatic force. Results show that pH and electric field can affect the surface charge density of glass and OTS surfaces immersed in saline solutions and DI water. The mechanisms of the effect of pH and electric field on the surface charge density are discussed. The slip length of the OTS surface immersed in saline solutions with two ionic concentrations and DI water with different pH values and electric field values is measured, and their effects on the slip length are analyzed from the point of surface charge. Results show that a larger absolute value of surface charge density leads to a smaller slip length for the OTS surface. PMID:23683055

  13. Method of forming a relatively stable slip of silicon metal particles and yttrium containing particles

    NASA Technical Reports Server (NTRS)

    Dickie, Ray A. (Inventor); Mangels, John A. (Inventor)

    1984-01-01

    The method concerns forming a relatively stable slip of silicon metal particles and yttrium containing particles. In one embodiment, a casting slip of silicon metal particles is formed in water. Particles of a yttrium containing sintering aid are added to the casting slip. The yttrium containing sintering aid is a compound which has at least some solubility in water to form Y.sup.+3 ions which have a high potential for totally flocculating the silicon metal particles into a semiporous solid. A small amount of a fluoride salt is added to the casting slip which contains the yttrium containing sintering aid. The fluoride salt is one which will produce fluoride anions when dissolved in water. The small amount of the fluoride anions produced are effective to suppress the flocculation of the silicon metal particles by the Y.sup.+3 ions so that all particles remain in suspension in the casting slip and the casting slip has both an increased shelf life and can be used to cast articles having a relatively thick cross-section. The pH of the casting slip is maintained in a range from 7.5 to 9. Preferably, the fluoride salt used is one which is based on a monovalent cation such as sodium or ammonia. The steps of adding the yttrium containing sintering aid and the fluoride salt may be interchanged if desired, and the salt may be added to a solution containing the sintering aid prior to addition of the silicon metal particles.

  14. Slip tendency analysis, fault reactivation potential and induced seismicity in a deep geothermal reservoir

    NASA Astrophysics Data System (ADS)

    Moeck, Inga; Kwiatek, Grzegorz; Zimmermann, Günter

    2009-11-01

    A slip tendency analysis is used to assess the reactivation potential of shear and dilational fractures in a deep geothermal reservoir in the Northeast German Basin, based on the notion that slip on faults is controlled by the ratio of shear to normal stress acting on the plane of weakness in the in situ stress field. The reservoir rocks, composed of Lower Permian sandstones and volcanics, were stimulated by hydraulic fracturing. A surprisingly low microseismic activity was recorded with moment magnitudes MW ranging from -1.0 to -1.8. The slip tendency analysis suggests a critically stressed reservoir exists in the sandstones, whereas the volcanic rocks are less stressed. Rock failure first occurs with an additional pore pressure of 20 MPa. Presumed failure planes form a conjugate set and strike NW and NE. Slip failure is more likely than tensional failure in the volcanic rocks because high normal stresses prevent tensional failure. These results from slip tendency analysis are supported by the spatial distribution of recorded microseismicity. Source characteristics indicate slip rather than extension along presumed NE striking failure planes. This suggests that slip tendency analysis is an appropriate method that can be used to understand reservoir behavior under modified stress conditions.

  15. Tailoring phase slip events through magnetic doping in superconductor-ferromagnet composite films.

    PubMed

    Bawa, Ambika; Jha, Rajveer; Sahoo, Sangeeta

    2015-01-01

    The interplay between superconductivity (SC) and ferromagnetism (FM) when embedded together has attracted unprecedented research interest due to very rare coexistence of these two phenomena. The focus has been mainly put into the proximity induced effects like, coexistence of magnetism and superconductivity, higher critical current, triplet superconductivity etc. However, very little attention has been paid experimentally to the role of magnetic constituent on triggering phase slip processes in the composite films (CFs). We demonstrate that less than 1?at.% of magnetic contribution in the CFs can initiate phase slip events efficiently. Due to advanced state-of-the-art fabrication techniques, phase slip based studies have been concentrated mainly on superconducting nanostructures. Here, we employ wide mesoscopic NbGd based CFs to study the phase slip processes. Low temperature current-voltage characteristics (IVCs) of CFs show stair-like features originated through phase slip events and are absent in pure SC films. Depending on the bias current and temperature, distinct regions, dominated by Abrikosov type vortex-antivortex (v-av) pairs and phase slip events, are observed. The results presented here open a new way to study the phase slip mechanism, its interaction with v-av pairs in two dimensions and hence can be useful for future photonic and metrological applications. PMID:26304594

  16. Tailoring phase slip events through magnetic doping in superconductor-ferromagnet composite films

    PubMed Central

    Bawa, Ambika; Jha, Rajveer; Sahoo, Sangeeta

    2015-01-01

    The interplay between superconductivity (SC) and ferromagnetism (FM) when embedded together has attracted unprecedented research interest due to very rare coexistence of these two phenomena. The focus has been mainly put into the proximity induced effects like, coexistence of magnetism and superconductivity, higher critical current, triplet superconductivity etc. However, very little attention has been paid experimentally to the role of magnetic constituent on triggering phase slip processes in the composite films (CFs). We demonstrate that less than 1?at.% of magnetic contribution in the CFs can initiate phase slip events efficiently. Due to advanced state-of-the-art fabrication techniques, phase slip based studies have been concentrated mainly on superconducting nanostructures. Here, we employ wide mesoscopic NbGd based CFs to study the phase slip processes. Low temperature current-voltage characteristics (IVCs) of CFs show stair-like features originated through phase slip events and are absent in pure SC films. Depending on the bias current and temperature, distinct regions, dominated by Abrikosov type vortex-antivortex (v-av) pairs and phase slip events, are observed. The results presented here open a new way to study the phase slip mechanism, its interaction with v-av pairs in two dimensions and hence can be useful for future photonic and metrological applications. PMID:26304594

  17. Geodetically resolved slip distribution of the 27 August 2012 Mw=7.3 El Salvador earthquake

    NASA Astrophysics Data System (ADS)

    Geirsson, H.; La Femina, P. C.; DeMets, C.; Hernandez, D. A.; Mattioli, G. S.; Rogers, R.; Rodriguez, M.

    2013-12-01

    On 27 August 2012 a Mw=7.3 earthquake occurred offshore of Central America causing a small tsunami in El Salvador and Nicaragua but little damage otherwise. This is the largest magnitude earthquake in this area since 2001. We use co-seismic displacements estimated from episodic and continuous GPS station time series to model the magnitude and spatial variability of slip for this event. The estimated surface displacements are small (<2 cm) due to the distance and low magnitude of the earthquake. We use TDEFNODE to model the displacements using two different modeling approaches. In the first model, we solve for homogeneous slip on free rectangular fault(s), and in the second model we solve for distributed slip on the main thrust, realized using different slab models. The results indicate that we can match the seismic moment release, with models indicating rupture of a large area, with a low magnitude of slip. The slip is at shallow-to-intermediate depths on the main thrust off the coast of El Salvador. Additionally, we observe a deeper region of slip to the east, that reaches towards the Gulf of Fonseca between El Salvador and Nicaragua. The observed tsunami additionally indicates near-trench rupture off the coast of El Salvador. The duration of the rupturing is estimated from seismic data to be 70 s, which indicates a slow rupture process. Since the geodetic moment we obtain agrees with the seismic moment, this indicates that the earthquake was not associated with aseismic slip.

  18. A slip model for rarefied gas flows above a moving surface with mass transfer

    NASA Astrophysics Data System (ADS)

    Wu, Lin

    2014-08-01

    A slip velocity boundary condition for rarefied gas flows above a moving surface with net mass transfer in-between is derived from kinetic theory. Tangential momentum transfer rate contribution from mass transfer of gas molecules at a moving surface is discovered to introduce an additional gas slip velocity, which is linearly proportional to the mass transfer rate and the average tangential velocity of gas molecules entering/leaving the gas flow domain through the surface. The mass transfer induced gas slip velocity component is very different from the previously studied slip velocity component due to velocity shearing. A generalized lubrication equation for rarefied gas flow is obtained from the derived slip velocity boundary condition. The slip velocity boundary condition and the lubrication equation are suitable for rarefied gas flows at arbitrary Knudsen number with mass transfer on bounding surfaces. Mass transfer such as evaporation/condensation and its induced gas slip velocity at moving surfaces are demonstrated to be able to significantly change gas flow pressure and velocity profiles, and thus have a dominant effect on micro/nanoscale gas flows with non-negligible mass transfer on bounding surfaces.

  19. Formation of tough composite joints

    SciTech Connect

    Brun, M.K.

    1997-05-01

    Joints which exhibit tough fracture behavior were formed in a composite with a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. In composites with BN coatings fibers were aligned uniaxially, while composites with Si{sub 3}N{sub 4}-coated fibers had a 0/90{degree} architecture. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure have been proposed. Joints with a simple overlap geometry (only a few fingers) would have to be very long in order to prevent brittle failure. Typical failure in these joints is caused by a crack propagating along the interfaces between the joint fingers. Joints of the same overall length, but with geometry changed to be symmetric about the joint centerline and with an extra shear surface exhibited tough fractures accompanied with extensive fiber pullout. The initial matrix cracking of these joints was relatively low because cracks propagated easily through the ends of the fingers. Joints with an optimized stepped sawtooth geometry produced composite-like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength from 9 to 25 MPa, by changing the fiber coating, increased matrix cracking and ultimate strength of the composite significantly. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints will permit building of structures containing joints with only a minor reduction of design stresses.

  20. Efficacy of a rubber outsole with a hybrid surface pattern for preventing slips on icy surfaces.

    PubMed

    Yamaguchi, Takeshi; Hsu, Jennifer; Li, Yue; Maki, Brian E

    2015-11-01

    Conventional winter-safety footwear devices, such as crampons, can be effective in preventing slips on icy surfaces but the protruding studs can lead to other problems such as trips. A new hybrid (rough and smooth) rubber outsole was designed to provide high slip resistance without use of protruding studs or asperities. In the present study, we examined the slip resistance of the hybrid rubber outsole on both dry (-10 °C) and wet (0 °C) icy surfaces, in comparison to three conventional strap-on winter anti-slip devices: 1) metal coils ("Yaktrax Walker"), 2) gritted (sandpaper-like) straps ("Rough Grip"), and 3) crampons ("Altagrips-Lite"). Drag tests were performed to measure static (SCOF) and dynamic (DCOF) coefficients of friction, and gait trials were conducted on both level and sloped ice surfaces (16 participants). The drag-test results showed relatively high SCOF (?0.37) and DCOF (?0.31) values for the hybrid rubber sole, at both temperatures. The other three footwear types exhibited lower DCOF values (0.06-0.20) when compared with the hybrid rubber sole at 0 °C (p < 0.01). Slips were more frequent when wearing the metal coils, in comparison to the other footwear types, when descending a slope at -10 °C (6% of trials vs 0%; p < 0.05). There were no other significant footwear-related differences in slip frequency, distance or velocity. These results indicate that the slip-resistance of the hybrid rubber sole on icy surfaces was comparable to conventional anti-slip footwear devices. Given the likely advantages of the hybrid rubber sole (less susceptibility to tripping, better slip resistance on non-icy surfaces), this type of sole should contribute to a decrease in fall accidents; however, further research is needed to confirm its effectiveness under a wider range of test conditions. PMID:26154199

  1. Variability of fault slip behavior along the San Andreas Fault in the San Juan Bautista Region

    NASA Astrophysics Data System (ADS)

    Taira, Taka'aki; Bürgmann, Roland; Nadeau, Robert M.; Dreger, Douglas S.

    2014-12-01

    An improved understanding of the time history of fault slip at depth is an essential step toward understanding the underlying mechanics of the faulting process. Using a waveform cross-correlation approach, we document spatially and temporally varying fault slip along the northernmost creeping section of the San Andreas Fault near San Juan Bautista (SJB), California, by systematically examining spatiotemporal behaviors of characteristically repeating earthquakes (CREs). The spatial distribution of pre-1998 SJB earthquake (1984-1998) fault slip rate inferred from the CREs reveals a ~15 km long low creep or partially locked section located near the 1998 Mw 5.1 SJB earthquake rupture. A finite-fault slip inversion reveals that the rupture of the 1998 SJB earthquake is characterized by the failure of a compact ~4 km2 asperity with a maximum slip of about 90 cm and corresponding peak stress drop of up to 50 MPa, whereas the mean stress drop is about 15 MPa. Following the 1998 earthquake, the CRE activity was significantly increased in a 5-10 km deep zone extending 2-7 km northwest of the main shock, which indicates triggering of substantial aseismic slip. The postseismic slip inferred from the CRE activity primarily propagated to the northwest and released a maximum slip of 9 cm. In this 5-10 km depth range, the estimated postseismic moment release is 8.6 × 1016 N m, which is equivalent to Mw 5.22. The aseismic slip distribution following the 1998 earthquake is not consistent with coseismic stress-driven afterslip but represents a triggered, long-lasting slow earthquake.

  2. Microstructural investigations of principal slip zones in carbonates, examples from shallow crustal strike-slip faults in the Northern Calcareous Alps (Austria)

    NASA Astrophysics Data System (ADS)

    Bauer, Helene; Grasemann, Bernhard; Decker, Kurt

    2014-05-01

    Faults in the upper crust can move episodically by seismic deformation (individual earthquake ruptures) and/or continuously by aseismic creep deformation. In carbonate fault zones, several studies have shown that seismic deformation produces very narrow principal slip zones (cm to mm wide) that accommodate most of the fault displacement during an individual earthquake. Within these principal slip zones, ultracataclasites containing the principal slip surface, fluidization of ultracataclastic sub-layers and clast cortex grains have been proposed to be characteristic for seismic slip. In contrast, pressure solution has been proposed as a mechanism of aseismic sliding along a fault. Spaced cleavage solution planes and associated veins indicate diffusive mass transfer and precipitation in pervasive vein networks. At micro-scale, calcite CPO in fine-grained matrix of principal slip zones has been suggested to result from post-seismic pressure solution creep. Here, we present field data from the Salzchtal-Ennstal-Mariazell-Puchberg (SEMP) fault system (Austria) to interpret the principal slip zones with regard to possible indicators of seismic or aseismic deformation. We investigated exhumed, ancient sinistral strike-slip faults in dolomite and limestone that formed during eastward lateral extrusion of the Eastern Alps during Oligocene to Lower Miocene. The faults belong to a system of convergent strike-slip duplexes that developed at a restraining bend on an eastern segment of the SEMP-fault system. Distinct fault cores contain cataclastic fault rocks differing in textural complexity. Microstructural analysis of cataclastic fault rocks was done using both, optical and electron microscopy. Microstructures reveal several cataclastic types that can be interpreted in terms of different stages of cataclastic evolution. Coarser grained, well cemented cataclasites underlie fine grained ultracataclastic layers. For at least two of the faults, cataclasites containing clast cortex grains as well as foliated ultracataclasites with polished slip surfaces may give evidence of seismic deformation. One particular fault contains limestone cataclasites that show significant overprint with stylolithes and associated veins with precipitation products. In some parts, dense arrays of closely spaced solution cleavage seams around rigid elements (clasts of cataclasite material) produce a pseudo SC-fabric. Pressure solution deformation also affects host rock material surrounding the fault core, producing completely disintegrated rock which we called pressure solution breccias. Samples from at least one fault give striking evidence of potential post-seismic pressure solution creep. The complex interaction and competition of cataclastic and pressure solution creep is yet poorly understood and will be the topic of more detailed future investigations.

  3. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Rail joints. 213.351 Section 213.351... Rail joints. (a) Each rail joint, insulated joint, and compromise joint shall be of a structurally sound design and dimensions for the rail on which it is applied. (b) If a joint bar is cracked,...

  4. 17 CFR 300.105 - Joint accounts.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Joint accounts. 300.105... Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying joint account” if it is owned jointly, whether by the owners thereof as joint tenants with the right...

  5. 17 CFR 300.105 - Joint accounts.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Joint accounts. 300.105... Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying joint account” if it is owned jointly, whether by the owners thereof as joint tenants with the right...

  6. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Rail joints. 213.351 Section 213.351... Rail joints. (a) Each rail joint, insulated joint, and compromise joint shall be of a structurally sound design and dimensions for the rail on which it is applied. (b) If a joint bar is cracked,...

  7. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Rail joints. 213.351 Section 213.351... Rail joints. (a) Each rail joint, insulated joint, and compromise joint shall be of a structurally sound design and dimensions for the rail on which it is applied. (b) If a joint bar is cracked,...

  8. 17 CFR 300.105 - Joint accounts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Joint accounts. 300.105... Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying joint account” if it is owned jointly, whether by the owners thereof as joint tenants with the right...

  9. 17 CFR 300.105 - Joint accounts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Joint accounts. 300.105... Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying joint account” if it is owned jointly, whether by the owners thereof as joint tenants with the right...

  10. 49 CFR 213.351 - Rail joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Rail joints. 213.351 Section 213.351... Rail joints. (a) Each rail joint, insulated joint, and compromise joint shall be of a structurally sound design and dimensions for the rail on which it is applied. (b) If a joint bar is cracked,...

  11. Finger joint injuries.

    PubMed

    Prucz, Roni B; Friedrich, Jeffrey B

    2015-01-01

    Finger joint dislocations and collateral ligament tears are common athletic hand injuries. Treatment of the athlete requires a focus on safe return to play and maximizing function. Certain dislocations, such as proximal interphalangeal and distal interphalangeal volar dislocations, may be associated with tendon injuries and must be treated accordingly. Treatment of other dislocations is ultimately determined by postreduction stability, with many dislocations amenable to nonoperative treatment (ie, immobilization followed by rehabilitation). Protective splinting does not necessarily preclude athletic participation. Minor bone involvement typically does not affect the treatment plan, but significant articular surface involvement may necessitate surgical repair or stabilization. Percutaneous and internal fixation are the mainstays of surgical treatment. Treatment options that do not minimize recovery or allow the patient to return to protected play, such as external fixation, are generally avoided during the season of play. Undertreated joint injuries and unrecognized ligament injuries can result in long term disability. PMID:25455398

  12. Achieving joint benefits from joint implementation

    SciTech Connect

    Moomaw, W.R.

    1995-11-01

    Joint Implementation (JI) appears to have been born with Applied Energy Services Guatemala project in 1988. That project, to plant 52 million trees, protect existing forests from cutting and fire, and enhance rural development, is being implemented by CARE Guatemala to offset 120 per cent of the emissions of a small coal burning power plant that has been built in Connecticut. Since that time, several utilities and governments have initiated additional projects. Not all of these necessarily consist of tree planting in other countries, but may consist of energy efficiency or energy conservation programs designed to reduce carbon emissions by at least as much as the additional releases from a new facility. All JI projects share the characteristic of linking the release of greenhouse gases in an industrial country with an offset that reduces or absorbs a comparable amount in another country. The emitter in the industrial country is willing to pay for the reduction elsewhere because costs are less than they would be at home.

  13. Laboratory characterization of rock joints

    SciTech Connect

    Hsiung, S.M.; Kana, D.D.; Ahola, M.P.; Chowdhury, A.H.; Ghosh, A.

    1994-05-01

    A laboratory characterization of the Apache Leap tuff joints under cyclic pseudostatic and dynamic loads has been undertaken to obtain a better understanding of dynamic joint shear behavior and to generate a complete data set that can be used for validation of existing rock-joint models. Study has indicated that available methods for determining joint roughness coefficient (JRC) significantly underestimate the roughness coefficient of the Apache Leap tuff joints, that will lead to an underestimation of the joint shear strength. The results of the direct shear tests have indicated that both under cyclic pseudostatic and dynamic loadings the joint resistance upon reverse shearing is smaller than that of forward shearing and the joint dilation resulting from forward shearing recovers during reverse shearing. Within the range of variation of shearing velocity used in these tests, the shearing velocity effect on rock-joint behavior seems to be minor, and no noticeable effect on the peak joint shear strength and the joint shear strength for the reverse shearing is observed.

  14. Formation of tough composite joints

    SciTech Connect

    Brun, M.K.

    1998-12-01

    Joints that exhibited tough fracture behavior were formed in a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure were proposed. Joints with a simple overlap geometry (only a few fingers) had to be very long in order to prevent brittle failure. Joints with an optimized stepped sawtooth geometry produced composite-like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength, by changing the fiber coating, significantly increased matrix cracking and ultimate strength of the joints. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints should permit building of structures containing joints with only a minor reduction of design stresses.

  15. Bonding effects on the slip differences in the B1 monocarbides.

    PubMed

    De Leon, Nicholas; Yu, Xiao-Xiang; Yu, Hang; Weinberger, Christopher R; Thompson, Gregory B

    2015-04-24

    Differences in plasticity are usually attributed to significant changes in crystalline symmetry or the strength of the interatomic bonds. In the B1 monocarbides, differences in slip planes exist at low temperatures despite having the same structure and very similar bonding characteristics. Our experimental results demonstrate concretely that HfC slips on {110} planes while TaC slips on {111} planes. Density functional theory calculations rationalize this difference through the formation of an intrinsic stacking fault on the {111} planes, formation of Shockley partials, and enhanced metallic bonding because of the valence filling of electrons between these transitional metal carbides. PMID:25955056

  16. 53 MHz beam loading compensation for slip stacking in the Fermilab Main Injector

    SciTech Connect

    Dey, J.; Kourbanis, I.; /Fermilab

    2005-05-01

    Recently In-Phase and Quadrature (I&Q) was added to both the 53 MHz Feedback and Feedforward Beam Loading Compensation for Slip Stacking in the Fermilab Main Injector. With 53 MHz Feedback, we can now turn the 18 Radio Frequency (RF) Stations off down to below 100 V. In using I&Q on Feedforward, beam loading compensation to the beam on both the upper and lower frequencies of Slip Stacking can be applied as we slip the beam. I&Q theory will be discussed.

  17. Giant amplification of interfacially driven transport by hydrodynamic slip: diffusio-osmosis and beyond

    E-print Network

    Armand Ajdari; Lyderic Bocquet

    2006-05-22

    We demonstrate that "moderate" departures from the no-slip hydrodynamic boundary condition (hydrodynamic slip lengths in the nanometer range) can result in a very large enhancement - up to two orders of magnitude- of most interfacially driven transport phenomena. We study analytically and numerically the case of neutral solute diffusio-osmosis in a slab geometry to account for non-trivial couplings between interfacial structure and hydrodynamic slip. Possible outcomes are fast transport of particles in externally applied or self-generated gradient, and flow enhancement in nano- or micro-fluidic geometries.

  18. The Hills are Alive: Dynamic Ridges and Valleys in a Strike-Slip Environment

    NASA Astrophysics Data System (ADS)

    Duvall, A. R.; Tucker, G. E.

    2014-12-01

    Strike-slip fault zones have long been known for characteristic landforms such as offset and deflected rivers, linear strike-parallel valleys, and shutter ridges. Despite their common presence, questions remain about the mechanics of how these landforms arise or how their form varies as a function of slip rate, geomorphic process, or material properties. We know even less about what happens far from the fault, in drainage basin headwaters, as a result of strike-slip motion. Here we explore the effects of horizontal fault slip rate, bedrock erodibility, and hillslope diffusivity on river catchments that drain across an active strike-slip fault using the CHILD landscape evolution model. Model calculations demonstrate that lateral fault motion induces a permanent state of landscape disequilibrium brought about by fault offset-generated river lengthening alternating with abrupt shortening due to stream capture. This cycle of shifting drainage patterns and base level change continues until fault motion ceases thus creating a perpetual state of transience unique to strike-slip systems. Our models also make the surprising prediction that, in some cases, hillslope ridges oriented perpendicular to the fault migrate laterally in conjunction with fault motion. Ridge migration happens when slip rate is slow enough and/or diffusion and river incision are fast enough that the hillslopes can respond to the disequilibrium brought about by strike-slip motion. In models with faster slip rates, stronger rocks or less-diffusive hillslopes, ridge mobility is limited or arrested despite the fact that the process of river lengthening and capture continues. Fast-slip cases also develop prominent steep fault-facing hillslope facets proximal to the fault valley and along-strike topographic profiles with reduced local relief between ridges and valleys. Our results demonstrate the dynamic nature of strike-slip landscapes that vary systematically with a ratio of bedrock erodibility (K) and hillslope diffusivity (D) to the rate of horizontal advection of topography (v). These results also reveal a potential set of recognizable geomorphic signatures within strike-slip systems that should be looked to as indicators of fault activity and/or material properties.

  19. Undulating slip in Laves phase and implications for deformation in brittle materials.

    PubMed

    Zhang, Wei; Yu, Rong; Du, Kui; Cheng, Zhiying; Zhu, Jing; Ye, Hengqiang

    2011-04-22

    By combining density-functional theory calculations and aberration-corrected transmission electron microscopy, dislocations in Laves phase (a typical complex intermetallic compound) are shown to slip in an undulating path. During the slip, the dislocation cores jump up and down between a weakly bound plane and an adjacent strongly bound plane for gliding and atomic shuffling, respectively. This is different from the conventional slip process in simple metals, which is continuous within a single plane, as described in the paradigm of the generalized stacking fault energy. PMID:21599384

  20. Imaging of early acceleration phase of the 2013-2014 Boso slow slip event

    NASA Astrophysics Data System (ADS)

    Fukuda, J.; Kato, A.; Obara, K.; Miura, S.; Kato, T.

    2014-12-01

    Based on GPS and seismic data, we examine the spatiotemporal evolution of a slow slip event (SSE) and associated seismic activity that occurred off the Boso peninsula, central Japan, from December 2013 to January 2014. We use GPS data from 71 stations of the GEONET and 6 stations operated by Earthquake Research Institute of the University of Tokyo and Tohoku University around the Boso peninsula. We apply a modified version of the Network Inversion Filter to the GPS time series at the 77 stations to estimate the spatiotemporal evolution of daily cumulative slip and slip rate on the subducting Philippine Sea plate. In addition, we create an improved earthquake catalog by applying a matched filter technique to continuous seismograms and examine the spatiotemporal relations between slow slip and seismicity. We find that the SSE started in early December 2013. The spatiotemporal evolution of slow slip and seismicity is divided into two distinct phases, an earlier slow phase from early to 30 December 2013 (Phase I) and a subsequent faster phase from 30 December 2013 to 9 January 2014 (Phase II). During Phase I, slip accelerated slowly up to a maximum rate of 1.6 m/yr with potentially accelerating?along-strike propagation at speeds on the order of 1 km/day or less and no accompanying seismicity. On the other hand, during Phase II, slip accelerated rapidly up to a maximum rate of 4.5 m/yr and then rapidly decelerated. The slip front propagated along strike at a constant speed of ~10 km/day. During the Phase II, slow slip was accompanied by seismic swarm activity that was highly correlated in space and time with slip rate, suggesting that the swarm activity was triggered by stress loading due to slow slip. Early slow acceleration of slip has not been identified in the past Boso SSEs in 1996, 2002, 2007, and 2011. It is not clear at this point whether the past Boso SSEs started with slow acceleration similarly to the 2013-2014 SSE. The transition from the slow to the faster phase shares some similarities with the nucleation of megathrust earthquakes inferred from foreshock activities, suggesting that SSEs may provide insights into the nucleation of large earthquakes.

  1. Determination of Slow Slip Episodes and Strain Accumulation along the Cascadia Margin

    NASA Astrophysics Data System (ADS)

    Holtkamp, S. G.; Brudzinski, M. R.; Demets, C.

    2006-12-01

    Continuous GPS stations in the PANGA network clearly record subduction-related strain accumulation and slow slip episodes along the Cascadia convergent margin. Many of the slow slip episodes have been correlated in time and space with seismic non-volcanic tremor signals, leading to the discovery of Episodic Tremor and Slip (ETS) process. In this study, we use a hyperbolic tangent curve fitting technique for the identification of slow slip times and magnitudes within the GPS time series, independent of seismic tremor data. We demonstrate the effectiveness of this automated technique for both identification of slow slip observations and calculation of slow slip displacements. Out of the 44 visually-confirmed observations recorded at 10 representative stations across the subduction zone, no false negatives and one false positive were recorded by the automated process. Overall, the algorithm finds 163 slow slip observations that reveal geographic variations in both recurrence and magnitude. Recurrence patterns in individual GPS observations demonstrate coherence among neighboring stations over time and apparent along-strike segmentation of the subduction interface. The average observed displacement magnitude during a slow slip episode varies from 1.2 mm to 6.2 mm, while the annual rate of slow slip displacement varies from .53 mm to 5.0 mm. The curve fitting routine also reveals rates of short-term strain accumulation before and after slow slip episodes that are 30% larger than rates of slow slip displacement, suggesting either that a significant amount of slow slip occurs below our detection threshold or that some other process accounts for the strain release. Comparison of these rates with the long-term strain accumulation indicates that the long-term trends in displacement are 4- -5 times larger at 100 km from the trench but the long- and short-term rates are equal at about 270 km from the trench. The patterns in strain accumulation are consistent with strong coupling in the shallow seismogenic zone and weak coupling in the deeper transitional zone.

  2. Nature of slip in {gamma}-titanium aluminide above the yield stress anomaly temperature

    SciTech Connect

    Jiao, S.; Bird, N.; Hirsch, P.B.; Taylor, G.

    1999-07-01

    Crystals of {gamma}-TiAl, containing {approximately}54.5 at%Al, with various orientations were deformed at different temperatures and examined by transmission electron microscopy (TEM). It was found that while in many cases slip and climb of ordinary dislocations tend to predominate, slip by [001] dislocations can be important also. The occurrence of [001] slip has not been reported before. The values of critical resolved shear stress were determined and strong locks on [001] dislocations have been identified as local segments of 1/2[{l{underscore}angle}112] dislocations arising from interactions between [001] and 1/2[{l{underscore}angle}110] dislocations.

  3. On the probability of cycle-slipping in first-order phase-locked loops.

    NASA Technical Reports Server (NTRS)

    La Frieda, J. R.

    1972-01-01

    The first-passage time boundary value problem for first-order phase-locked loops (PLL) is analyzed, and spectral representations are developed for the probability density function (pdf), the distribution function, and the moments of the first time to passage (or cycle-slip). For the sinusoidal PLL, an asymptotic formula, that is surprisingly accurate even at low loop SNR's and large frequency offsets, is obtained for the pdf of the time to cycle-slip, in terms of the mean time to slip.

  4. San Andreas-sized Strike-slip Fault on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This mosaic of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, about the size of the California portion of the San Andreas fault, which runs from the California-Mexico border north to the San Francisco Bay.

    In a strike-slip fault, two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. Overall motion along the fault seems to have followed a continuous narrow crack along the feature's entire length, with a path resembling steps on a staircase crossing zones that have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. The fault's opposite sides can be reconstructed like a puzzle, matching the shape of the sides and older, individual cracks and ridges broken by its movements.

    [figure removed for brevity, see original site]

    The red line marks the once active central crack of the fault. The black line outlines the fault zone, including material accumulated in the regions which have been pulled apart.

    Bends in the fault have allowed the surface to be pulled apart. This process created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling-apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, in Death Valley and the Dead Sea. In those cases, the pulled-apart regions can include upwelled materials, but may be filled mostly by sedimentary and eroded material from above.

    One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. Tidal tension opens the fault and subsequent tidal stress causes it to move lengthwise in one direction. Then tidal forces close the fault again, preventing the area from moving back to its original position. Daily tidal cycles produce a steady accumulation of lengthwise offset motions. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces.

    North is to the top of the picture and the sun illuminates the surface from the top. The image, centered at 66 degrees south latitude and 195 degrees west longitude, covers an area approximately 300 by 203 kilometers(185 by 125 miles). The pictures were taken on September 26, 1998by Galileo's solid-state imaging system.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  5. Dynamic weakening by nanoscale smoothing during high velocity fault slip

    NASA Astrophysics Data System (ADS)

    Chen, X.; Madden, A. S.; Bickmore, B. R.; Reches, Z.

    2012-12-01

    Rock friction is commonly determined through measurements on rock samples with areas from a few cm^2 to 1 m^2. On the other hand, theoretical models suggest that frictional processes are scale-dependent, and active at scales of a few microns or less. We used Atomic Force Microscope (AFM) to determine the frictional strength and roughness of experimental fault surfaces that slipped under high velocity (< 0.9 m/s) and moderate normal stress (< 7.0 MPa). The high velocity tests (Reches and Lockner, 2010) were conducted on experimental faults made of Sierra White granite (SWG) and Kasota dolomite (KD), and the sheared surfaces were sampled for the nanoscale measurements by the AFM. The friction coefficient (FC) at the sub-micron scale was measured by using the AFM to press & shear a tiny silica glass bead against the rock surface (Stiernstedt et al., 2005). The 3D morphology of the fault surfaces at the nano- to microscale was measured with the standard AFM intermittent contact mode with sharp tip probe. In the AFM friction measurements, a total of 43 sites have been measured and each site was repeated hundreds of times; 33 of these sites were measured under air and 10 sites were measured under deionized water. The SWG and KD samples display FC values that vary systematically with orientation and conditions. Room-dry, un-sheared surfaces have FC = 0.64 ± 0.05 for both rock types. KD normal to striations has FC = 0.60 ± 0.15. SWG rough, sheared surface display FC = 0.71 ± 0.02. Significant friction drop was observed under dry, parallel to striations, with FC = 0.34 ± 0.08 (KD) and FC = 0.52 ± 0.03 (SWG). Under wet (water covered) conditions parallel to slickensides, the friction dropped even further to FC = 0.15 ± 0.05 (dolomite) and FC = 0.31 ± 0.05 (granite). The nanoscale FC (room dry, parallel to striations) is comparable to the macroscopic FC for the host experiments. Roughness calculations are based on AFM topographic images, and analyzed by both Power Spectral Density (PSD) and RMS. The PSD curves display a clear, expected trend: the cleaved biotite is the smoothest surface, the un-sheared surface is the roughest, and the roughness of profiles parallel-and normal-to striations in-between. A systematic change of the PSD slope, beta, was observed. The un-sheared profiles have steep PSD curves, with beta = 2.3 ± 0.1, and profiles measured normal to the striations are smoother, but with similar slope. Profiles parallel to the striations are even smoother and with beta = 1.4 ± 0.4, indicating distinct roughness anisotropy. The RMS roughness was calculated along 1 micron segments either slip-parallel or slip-normal from the profile data. The relation between the AFM friction coefficients and the RMS indicate that at length scales of 0.01-10 microns, friction coefficients strongly correlate with roughness. We noted that surfaces with RMS > 0.1 micron, have FC approaching the "universal" friction coefficient of 0.6-0.85 (Byerlee law). We propose that fault smoothing under high velocity is an effective driving mechanism for dynamic weakening and earthquake instability.

  6. Prosthetic elbow joint

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce C. (inventor)

    1994-01-01

    An artificial, manually positionable elbow joint for use in an upper extremity, above-elbow, prosthetic is described. The prosthesis provides a locking feature that is easily controlled by the wearer. The instant elbow joint is very strong and durable enough to withstand the repeated heavy loadings encountered by a wearer who works in an industrial, construction, farming, or similar environment. The elbow joint of the present invention comprises a turntable, a frame, a forearm, and a locking assembly. The frame generally includes a housing for the locking assembly and two protruding ears. The forearm includes an elongated beam having a cup-shaped cylindrical member at one end and a locking wheel having a plurality of holes along a circular arc on its other end with a central bore for pivotal attachment to the protruding ears of the frame. The locking assembly includes a collar having a central opening with a plurality of internal grooves, a plurality of internal cam members each having a chamfered surface at one end and a V-shaped slot at its other end; an elongated locking pin having a crown wheel with cam surfaces and locking lugs secured thereto; two coiled compression springs; and a flexible filament attached to one end of the elongated locking pin and extending from the locking assembly for extending and retracting the locking pin into the holes in the locking wheel to permit selective adjustment of the forearm relative to the frame. In use, the turntable is affixed to the upper arm part of the prosthetic in the conventional manner, and the cup-shaped cylindrical member on one end of the forearm is affixed to the forearm piece of the prosthetic in the conventional manner. The elbow joint is easily adjusted and locked between maximum flex and extended positions.

  7. Modulation of Whillans Ice Stream Stick Slip Cycle: Loading Rate, Subglacial Hydrology and Slowdown

    NASA Astrophysics Data System (ADS)

    Beem, L.; Tulaczyk, S. M.; Fricker, H.; King, M. A.

    2013-12-01

    The Whillans Ice Stream (WIS) is one of the fast flowing glaciers that discharges ice from West Antarctica into the Ross Ice Shelf. WIS moves by a tidally modulated stick-slip motion where for 6 to 24 hours the glacier slides slowly (~200 m/yr) followed by short periods (30 minutes) of fast sliding (slip event) in excess of ~3000 m/yr equivalent. Slip events are thought to nucleate at a consistent geographic region beneath the glacier when basal stress exceeds the yield strength of the bed. Data from continuous GPS station deployed on the surface of WIS between December 2007 and May 2013 observed surface displacement of the ice stream including more than 3100 stick-slip cycles. In 2008, WIS experienced a 6 month speed up of 2% during subglacial lake activity. WIS has been slowing since at least the 1960';s with current deceleration at the greatest recorded magnitude (10 m/yr2). Changes in annual ice discharge from velocity variability are between 6% and 14% of the catchments estimated +5 Gt/yr annual mass budget imbalance. Recent changes in ice velocity over both short time scales, subglacial lake drainage, and long term, multi-year deceleration, result from modulation of the stick-slip cycle by changing basal resistive strength and the rate of basal stress accumulation at slip nucleation sites. Although the basal resistance is changing on a regional scale, modeling of stress accumulation showed no change in the magnitude of the stress threshold necessary to initiate slip events over the duration of the observations. Suggesting that slip nucleation sites are not included in the regions of change or unaffected by basal hydrological changes. Instead, slip frequency and slow sliding speeds changed in response to basal resistive stress. Subglacial Lake Whillans filled and drained over a year period in 2008 and 2009 and increased basal water pressures across a region of WIS bed. Increased slip frequency during subglacial lake activity accounts for 90 to 100% of the extra displacement during the 2008 speed up. Basal resistance in regions with elevated basal water pressure is reduced and may have been redistributed towards slip nucleation sites increasing the rate of stress accumulation. Greater rates of stress accumulation result in more frequently occurring slip events. Once subglacial hydrologic activity ceases in early 2009, WIS resumes a trend of deceleration through the end of the observational period. The decrease in velocity is a combination of the reduction of both the slip frequency (-30 slips/yr) and slow sliding rates (-8 m/yr2). Increasing basal resistance over some portion of the bed (20 to 40 Pa/yr), possibility through till strengthening by draining of pore water, decreases slow sliding rates and prevents some stress from accumulating at slip nucleation sites. An increasing magnitude of basal resistance supported over a broad region of the bed continues to lower the rate of stress accumulation at slip nucleation sites and decreases slip frequency through time. Basal resistive stress change, in response to hydrological activity, is the most significant cause of current observed changes of WIS surface velocity and reinforces the importance of internal thermo-dynamic feedbacks to the sensitivity of glacier motion.

  8. Imaging transient slip events in southwest Japan using reanalyzed Japanese GEONET GPS time series

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Moore, A. W.; Owen, S. E.

    2012-12-01

    The Japanese continuous GPS network (GEONET) with ~1450 stations provide a unique opportunity to study ongoing subduction zone dynamics, and crustal deformation at various spatiotemporal scales. Recently we completed a reanalysis of GPS position time series for the entire GEONET from 1996 to 2012 using JPL GIPSY/OASIS-II based GPS Network Processor [Owen et al., 2006] and raw data provided by Geospatial Information Authority of Japan (GSI) and Caltech. We use the JPL precise GPS orbits reestimated from the present through 1996 [Desai et al., 2011], troposphere global mapping function, and single receiver phase ambiguity resolution strategy [Bertiger et al., 2010] in the analysis. The resultant GPS time series solution shows improved repeatability and consistency over the ~16 yrs span, in comparison with 1996-2006 GPS position estimates used in our previous analysis [Liu et al., 2010a,b]. We apply a time-series analysis framework to estimate bias, offsets caused by instrument changes, earthquakes and other unknown sources, linear trends, seasonal variations, post-seismic deformation and other transient signals. The principal component analysis method is used to estimate the common mode error across the network [Dong et al. 2006]. We construct an interplate fault geometry from a composite plate boundary model [Wang et al. 2004] and apply a Kalman filter based network inversion method to image the spatiotemporal slip variation of slip transient events on the plate interface. The highly precise GPS time series enables the detectability of much smaller transient signals and start to reveal previously unobserved features of slow slip events. For example, the application to 2009-2011 Bungo Channel slow slip event shows it has a complex slip history with the major event initiating in late 2009 beneath the northeast corner of the region and migrating southwestward and updip. At ~2010.75 there is activation of a smaller slip subevent to the east of main slip region, persisting through the end of modeling period (2011.1786). We found clear temporal correspondence of adjacent low frequency earthquakes (LFEs)/tremor following transient slip variation, similar to what we found for other slip events in the region. This indicates that transient slip acts as a driving force to modulate the occurrence of LFEs/tremor. Despite many similarities between 2009-2011 and 2002-2004 slip events, there is considerable difference between the two in terms of slip details, suggesting these recurrent episodic events are not exactly identical. We find the 2009-2011 Bungo Channel event as well as previous ones (e.g, 2002-2004, 1996-1998) all initiated at the same location on the plate interface, suggesting that they are controlled by inherent frictional properties with secondary factors affecting the evolution details. Integrating plate coupling and SSEs confirmed the spatial pattern seen before in other events that the transient slip zones are located in a region between the locked zones and the epicenters of the LFEs/tremor. Recurrent SSEs release nearly all accumulated elastic strain over depths of ~20-30km where slip occurs and at least part of slip deficit at a shallower depth. We are in the process of imaging other slip transients along this part of subduction margin in a systematic effort to improve estimates of slip deficits and future large earthquake hazards.

  9. Global strike-slip fault distribution on Enceladus reveals mostly left-lateral faults

    NASA Astrophysics Data System (ADS)

    Martin, E. S.; Kattenhorn, S. A.

    2013-12-01

    Within the outer solar system, normal faults are a dominant tectonic feature; however, strike-slip faults have played a role in modifying the surfaces of many icy bodies, including Europa, Ganymede, and Enceladus. Large-scale tectonic deformation in icy shells develops in response to stresses caused by a range of mechanisms including polar wander, despinning, volume changes, orbital recession/decay, diurnal tides, and nonsynchronous rotation (NSR). Icy shells often preserve this record of tectonic deformation as patterns of fractures that can be used to identify the source of stress responsible for creating the patterns. Previously published work on Jupiter's moon Europa found that right-lateral strike-slip faults predominantly formed in the southern hemisphere and left-lateral strike-slip faults in the northern hemisphere. This pattern suggested they were formed in the past by stresses induced by diurnal tidal forcing, and were then rotated into their current longitudinal positions by NSR. We mapped the distribution of strike-slip faults on Enceladus and used kinematic indicators, including tailcracks and en echelon fractures, to determine their sense of slip. Tailcracks are secondary fractures that form as a result of concentrations of stress at the tips of slipping faults with geometric patterns dictated by the slip sense. A total of 31 strike-slip faults were identified, nine of which were right-lateral faults, all distributed in a seemingly random pattern across Enceladus's surface, in contrast to Europa. Additionally, there is a dearth of strike-slip faults within the tectonized terrains centered at 90°W and within the polar regions north and south of 60°N and 60°S, respectively. The lack of strike-slip faults in the north polar region may be explained, in part, by limited data coverage. The south polar terrain (SPT), characterized by the prominent tiger stripes and south polar dichotomy, yielded no discrete strike-slip faults. This does not suggest that the SPT is devoid of shear: previous work has indicated that the tiger stripes may be undergoing strike-slip motions and the surrounding regions may be experiencing shear. The fracture patterns and geologic activity within the SPT have been previously documented to be the result of stresses induced by both NSR and diurnal tidal deformation. As these same mechanisms are the main controls on strike-slip fault patterns on Europa, the lack of a match between strike-slip patterns on Europa and Enceladus is intriguing. The pattern of strike-slip faults on Enceladus suggests a different combination of stress mechanisms is required to produce the observed distributions. We will present models of global stress mechanisms to consider how the global-scale pattern of strike-slip faults on Enceladus may have been produced. This problem will be investigated further by measuring the angles at which tailcracks have formed on Enceladus. Tailcracks produced by simple shear form at 70.5° to the fault. Any deviation from this angle indicates some ratio of concomitant shear and dilation, which may provide insights into elucidating the stresses controlling strike-slip formation on Enceladus.

  10. Nucleation of Northern Cascadia Episodic Tremor and Slip Events

    NASA Astrophysics Data System (ADS)

    Creager, K. C.; Klaus, A. J.; Wech, A.; Houston, H.; Vidale, J. E.

    2011-12-01

    The fascinating propagation behavior of the rupture front during episodic tremor and slip (ETS) events in Cascadia and Japan has received a great deal of attention documenting a roughly 8 km/day along-strike propagation, rapid tremor reversals propagating an order of magnitude faster, and tremor streaks aligned with the slip vector propagating two orders of magnitude faster. Thus far, the initiation phase of ETS has received less scrutiny. We find that Northern Cascadia ETS typically initiate near the down-dip end of the tremor-capable zone and propagate up dip during a period of roughly 5 days until they fill the width of the ETS zone. Then they propagate along strike in one or both directions at roughly 8 km/day. During the initiation phase, the area tremoring per day grows systematically, and approximately linearly. During this initiation phase, tremor-source amplitude also grows systematically, before achieving maximum amplitudes, followed by along-strike propagation often with wild variations in amplitude that seem to be strongly influenced by tidal stresses. It appears that the increase in amplitude is due primarily to an increase in source area, such that the source amplitude per unit area is roughly constant. Tremor source amplitude is proportional to the root-mean square of band-limited (1.5 to 5.5 Hz) ground velocity for every 5-minute window and is estimated using a method similar to Maeda and Obara [JGR, 2009]. We use horizontal-component seismograms from the Array of Arrays and CAFE experiments. Tremor locations, calculated using a waveform envelope cross-correlation method [Wech and Creager, GRL, 2008], are used to invert for source amplitude and station statics correcting for geometric spreading and seismic attenuation. It appears that there is a distinct ETS initiation phase with a duration of order five days during which the tremor amplitudes systematically increase and tremor often migrates updip filling the width of the tremor-capable zone. This is followed by a systematic along-strike propagation in one or both directions.

  11. Deep-seated downslope slip during strong seismic shaking

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.

    2011-12-01

    Strong seismic waves cause frictional failure within regolith on hillslopes. The material responds anelastically to the combined oscillating dynamic and static gravitational stresses. Gravity drives preferential downslope movement of the transiently weakened material. The net effect over many earthquake cycles is a tens of meter thick slow landslide, that is a sackung. The classical approach to hillside failure involves downslope dynamic accelerations or equivalently downslope dynamic shear tractions. Rate and state friction quantifies that the starting coefficient of friction is a few tenths higher that the apparent long-term coefficient of friction from the angle of repose, 0.96-1.25 in the calculations, retaining an extra digit. Furthermore, the dynamic Coulomb stress ratio for dynamic to lithostatic stress for S-waves refracted toward vertical paths is the dynamic acceleration in g's above the scale depth 1/k, the inverse of the wave number. In more detail, a dynamic acceleration of 0.13-0.35 g destabilizes slopes near the angle of repose. Seismologists expect such acceleration near active major faults, compatible with the widespread occurrence of sackungen on steep slopes. Accelerations of 0.96-1.25 = ˜1 g destabilize shallow slopes, leading to net downhill movement, analogous to the movement of an object down a vibrating ramp. However, sackungen are rare or even absent on shallow slopes in California indicating the rarity of sustained 1 g accelerations. A second mechanism may drive downhill movement on modest ˜19° slopes as observed in the San Gabriel Mountains of California near the San Andreas Fault. The near-field velocity pulse on strike-slip faults produces only a few tenths g acceleration but particle velocities of over 1 m s-1 persisting over >1 s. Dynamic stresses and strains scale with this velocity and extend all the way to the free surface. Coulomb failure criteria are exceeded at shallow depths. Failure greatly weakens the regolith allowing it to move downhill in response to gravity. This mechanism appears capable of producing prehistoric 1 m per event slip on modest slopes observed in the San Gabriel Mountains.

  12. Aftershock distribution as a constraint on the geodetic model of coseismic slip for the 2004 Parkfield earthquake

    USGS Publications Warehouse

    Bennington, Ninfa; Thurber, Clifford; Feigl, Kurt; Murray-Moraleda Jessica

    2011-01-01

    Several studies of the 2004 Parkfield earthquake have linked the spatial distribution of the event’s aftershocks to the mainshock slip distribution on the fault. Using geodetic data, we find a model of coseismic slip for the 2004 Parkfield earthquake with the constraint that the edges of coseismic slip patches align with aftershocks. The constraint is applied by encouraging the curvature of coseismic slip in each model cell to be equal to the negative of the curvature of seismicity density. The large patch of peak slip about 15 km northwest of the 2004 hypocenter found in the curvature-constrained model is in good agreement in location and amplitude with previous geodetic studies and the majority of strong motion studies. The curvature-constrained solution shows slip primarily between aftershock “streaks” with the continuation of moderate levels of slip to the southeast. These observations are in good agreement with strong motion studies, but inconsistent with the majority of published geodetic slip models. Southeast of the 2004 hypocenter, a patch of peak slip observed in strong motion studies is absent from our curvature-constrained model, but the available GPS data do not resolve slip in this region. We conclude that the geodetic slip model constrained by the aftershock distribution fits the geodetic data quite well and that inconsistencies between models derived from seismic and geodetic data can be attributed largely to resolution issues.

  13. Slow slip below Port Blair, Andaman, during the great Sumatra-Andaman earthquake of 26 December 2004

    NASA Astrophysics Data System (ADS)

    Singh, S. K.; Ortiz, M.; Gupta, H. K.; Ramadass, D. G. A.

    2006-02-01

    Although several studies suggest that a slow slip followed the seismic slip on the northern half of the 1300-km long plate interface that ruptured during the great Sumatra-Andaman earthquake, the onset and duration of the slow slip remain unresolved. In this paper we analyze a tide gauge record at Port Blair, situated about 1000 km north of the epicenter. Our preferred model, which fits the observed data well, consists of a mixed mode of slip: ~half of the total slip occurring seismically in less than 5 min after the rupture arrival and the rest developing in the next 30 min. A scenario of slow slip on the northern half of the rupture area, that is consistent with seismic data, and GPS data, consists of slip on the time scale of <35 min over some parts of the fault, such as below Port Blair, and > 1 hour over the rest.

  14. A comparative study of two statistical approaches for the analysis of real seismicity sequences and synthetic seismicity generated by a stick-slip experimental model

    NASA Astrophysics Data System (ADS)

    Flores-Marquez, Leticia Elsa; Ramirez Rojaz, Alejandro; Telesca, Luciano

    2015-04-01

    The study of two statistical approaches is analyzed for two different types of data sets, one is the seismicity generated by the subduction processes occurred at south Pacific coast of Mexico between 2005 and 2012, and the other corresponds to the synthetic seismic data generated by a stick-slip experimental model. The statistical methods used for the present study are the visibility graph in order to investigate the time dynamics of the series and the scaled probability density function in the natural time domain to investigate the critical order of the system. This comparison has the purpose to show the similarities between the dynamical behaviors of both types of data sets, from the point of view of critical systems. The observed behaviors allow us to conclude that the experimental set up globally reproduces the behavior observed in the statistical approaches used to analyses the seismicity of the subduction zone. The present study was supported by the Bilateral Project Italy-Mexico Experimental Stick-slip models of tectonic faults: innovative statistical approaches applied to synthetic seismic sequences, jointly funded by MAECI (Italy) and AMEXCID (Mexico) in the framework of the Bilateral Agreement for Scientific and Technological Cooperation PE 2014-2016.

  15. No slip locomotion of hatchling sea turtles on granular media

    NASA Astrophysics Data System (ADS)

    Mazouchova, Nicole; Li, Chen; Gravish, Nick; Savu, Andrei; Goldman, Daniel

    2009-11-01

    Sea turtle locomotion occurs predominantly in aquatic environments. However after hatching from a nest on a beach, the juvenile turtles (hatchlings), must run across several hundred meters of granular media to reach the water. To discover how these organisms use aquatically adapted limbs for effective locomotion on sand, we use high speed infrared video to record hatchling Loggerhead sea turtles (Caretta caretta) kinematics in a field site on Jekyll Island, GA, USA. A portable fluidized bed trackway allows variation of the properties of the granular bed including volume fraction and angle up to the angle of repose. Despite being adapted for life in water, on all treatments the turtles use strategies similar to terrestrial organisms when moving on sand. Speeds up to 3 BL/sec are generated not by paddling in sand, but by limb movement that minimizes slip of the flippers, thus maintaining force below the yield stress of the medium. We predict turtle speed using a model which incorporates the yield stress of the granular medium as a function of surface angle.

  16. Anelastic response of the earth to a dip slip earthquake

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Raefsky, A.

    1983-01-01

    The deformation induced by a vertical dip slip earthquake is examined using a variety of rheologic models. In this way the complications of dipping faults are avoided, and the phenomenon of transient peripheral warping is clearly revealed. A thrust fault dipping at 30 deg is investigated, and the important effects of dip and the existence of a slab on the asymmetry of strain pulses propagated into the overthrust and subducted lithosphere are demonstrated. One of the signal results of the study is the essential similarity of the strain patterns for Newtonian and non-Newtonian flow laws: the two rheologies give nearly identical strain field geometries. The principal difference between the two, which is readily observable, is in their time evolution. Relaxation in non-Newtonian rheologies tends to be initially fast, then slow at times that are late in comparison with relaxation in a Newtonian rheology. The possibility of simply recalling the time dependence of a Newtonian solution to obtain an approximate solution to a non-Newtonian problem is demonstrated.

  17. On the origin of Umtanum Ridge: Kinematics of Neogene slip

    NASA Astrophysics Data System (ADS)

    Miller, Brendan A.

    Constraining the geometry of active faults is an important step in determining accurate estimates of regional seismic hazard. Where subsurface data are lacking, the shape of hanging wall folds can be used to interpret fault geometry at depth. In order to better understand the seismic hazard posed by the Yakima folds in central Washington, I produced a new geologic map and employ kinematic modeling techniques to probe the geometry of a reverse/thrust fault controlling folding of the Columbia River Basalt flows at Umtanum Ridge near Ellensburg, WA. Depending on the technique used, Umtanum Ridge may have formed from either thin or thick-skinned deformation. My preferred model, using a combination of fault-bend and trishear fault-propagation folding, is consistent will measured flow top attitudes along a line of section through the ridge. This model implies that up to 520 m of slip has occurred since 15.6 Ma on a fault soling in a detachment ˜4 km deep. The rate of deformation derived from the model underestimates (by a factor of 2) previously published rates derived from both geodetic and geomorphic data, implying that current rates of deformation may be higher than the long term average.

  18. Wear processes in rocks at slow to high slip rates

    NASA Astrophysics Data System (ADS)

    Hirose, Takehiro; Mizoguchi, Kauzo; Shimamoto, Toshihiko

    2012-05-01

    Frictional wear experiments are performed on diorite, granite and sandstone at sliding velocities of 0.004-0.27 m/s under normal stresses of 0.21-6.3 MPa using a rotary-shear apparatus, to establish velocity-dependent wear laws of rocks and to determine the partition of frictional work used for gouge generation. Power-laws between normal/shear stresses and steady-state wear rate, defined as (thickness of gouge formed)/(fault displacement), account for our data for diorite and granite at low velocities and most experimental data on wear of rocks reported in the literature. But an exponential law holds for wear of diorite at velocities greater than 0.11 m/s and its wear rate increases dramatically at seismic slip rates. A change from the power-law to the exponential law seems to be caused by frictional heating and thermal fracturing. Both power and exponential laws can describe data for granite. Sandstones exhibit complex wear behavior possibly due to development of shiny slickenside surface that suppresses wear. Our data for diorite indicate that, at the investigated normal stresses, only 0.004% of frictional work is consumed for gouge formation at velocities less than 0.11 m/s, but this fraction increases markedly with increasing velocity. Energy partition for gouge formation is not constant and changes with velocity during earthquakes.

  19. Greenland supraglacial lake drainages triggered by hydrologically induced basal slip

    NASA Astrophysics Data System (ADS)

    Stevens, Laura A.; Behn, Mark D.; McGuire, Jeffrey J.; Das, Sarah B.; Joughin, Ian; Herring, Thomas; Shean, David E.; King, Matt A.

    2015-06-01

    Water-driven fracture propagation beneath supraglacial lakes rapidly transports large volumes of surface meltwater to the base of the Greenland Ice Sheet. These drainage events drive transient ice-sheet acceleration and establish conduits for additional surface-to-bed meltwater transport for the remainder of the melt season. Although it is well established that cracks must remain water-filled to propagate to the bed, the precise mechanisms that initiate hydro-fracture events beneath lakes are unknown. Here we show that, for a lake on the western Greenland Ice Sheet, drainage events are preceded by a 6-12 hour period of ice-sheet uplift and/or enhanced basal slip. Our observations from a dense Global Positioning System (GPS) network allow us to determine the distribution of meltwater at the ice-sheet bed before, during, and after three rapid drainages in 2011-2013, each of which generates tensile stresses that promote hydro-fracture beneath the lake. We hypothesize that these precursors are associated with the introduction of meltwater to the bed through neighbouring moulin systems (vertical conduits connecting the surface and base of the ice sheet). Our results imply that as lakes form in less crevassed, interior regions of the ice sheet, where water at the bed is currently less pervasive, the creation of new surface-to-bed conduits caused by lake-draining hydro-fractures may be limited.

  20. Greenland supraglacial lake drainages triggered by hydrologically induced basal slip.

    PubMed

    Stevens, Laura A; Behn, Mark D; McGuire, Jeffrey J; Das, Sarah B; Joughin, Ian; Herring, Thomas; Shean, David E; King, Matt A

    2015-06-01

    Water-driven fracture propagation beneath supraglacial lakes rapidly transports large volumes of surface meltwater to the base of the Greenland Ice Sheet. These drainage events drive transient ice-sheet acceleration and establish conduits for additional surface-to-bed meltwater transport for the remainder of the melt season. Although it is well established that cracks must remain water-filled to propagate to the bed, the precise mechanisms that initiate hydro-fracture events beneath lakes are unknown. Here we show that, for a lake on the western Greenland Ice Sheet, drainage events are preceded by a 6-12 hour period of ice-sheet uplift and/or enhanced basal slip. Our observations from a dense Global Positioning System (GPS) network allow us to determine the distribution of meltwater at the ice-sheet bed before, during, and after three rapid drainages in 2011-2013, each of which generates tensile stresses that promote hydro-fracture beneath the lake. We hypothesize that these precursors are associated with the introduction of meltwater to the bed through neighbouring moulin systems (vertical conduits connecting the surface and base of the ice sheet). Our results imply that as lakes form in less crevassed, interior regions of the ice sheet, where water at the bed is currently less pervasive, the creation of new surface-to-bed conduits caused by lake-draining hydro-fractures may be limited. PMID:26040890