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1

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

SciTech Connect

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

Mulcahy, T.M.

1984-10-01

2

Slip joint connector  

NASA Technical Reports Server (NTRS)

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

Thomas, Frank P. (inventor)

1994-01-01

3

Tubular spring slip joint and jar  

SciTech Connect

The present invention comprises a pressure balanced tubular spring slip-joint and jar including a generally tubular outer housing having longitudinal slot means in the wall thereof, and a hammer area of increased wall thickness at one end thereof, within which housing slidably extends a jar mandrel means having first and second longitudinally spaced enlarged diameter anvil areas, at least one fastener tapped into one of those anvil areas, the heads of said fastener protruding into said slot means. Both said housing and said mandrel means possesses axial bores therethrough, which are placed in communication via the bore of a tubular spring within the housing, whereby during extension and contraction of the slip-joint and jar means of the present invention the area within said axial bores and said spring bore is of a constant volume. The invention may be employed to provide force impulses in either longitudinal direction, said tubular spring aiding the application of those impulses when said housing and said mandrel means move relatively toward each other. By proper selection of spring length and use of a coiled spring having spaced coils, the present invention may also be employed as a bi-directional shock absorber.

Heemstra, T. R.

1985-04-23

4

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

E-print Network

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 ...

Yang, Lu

5

Coseismic slip model of the 2008 Wenchuan earthquake derived from joint inversion of interferometric synthetic aperture  

E-print Network

"shallow slip deficit" in the slip depth distribution of this mixed mechanism earthquake. Aftershocks wereClick Here for Full Article Coseismic slip model of the 2008 Wenchuan earthquake derived from joint; published 28 April 2010. [1] We derived a coseismic slip model for the Mw 7.9 2008 Wenchuan earthquake

Fialko, Yuri

6

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

EPA Science Inventory

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

7

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

EPA Science Inventory

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

8

A tube-in-tube water\\/zeotropic mixture condenser: design procedure against experimental data  

Microsoft Academic Search

The object of the present paper is related to the design of condensers for the non-azeotropic mixtures of refrigerants. The high temperature glide mixture R-125\\/236ea at three different compositions (0.30\\/0.70, 0.46\\/0.54, 0.64\\/0.36 by mass) was tested during condensation inside a 2 m long smooth horizontal tube-in-tube exchanger. The superheated vapour entering the tube is first cooled and then condensed against

A. Cavallini; G. Censi; D. Del Col; L. Doretti; G. A. Longo; L. Rossetto

2002-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

10

SnO? tube-in-tube nanostructures: Cu@C nanocable templated synthesis and their mutual interferences between heavy metal ions revealed by stripping voltammetry.  

PubMed

SnO2 tube-in-tube nanostructures are synthesized using Cu@C nanocables as effective sacrificial templates. It is revealed by stripping voltammetry that SnO2 tube-in-tube nanostructures show excellent performances in the determination of heavy metal ions, which might be related to the extraordinary adsorbing capacities of the hollow structure to metal ions, i.e., metal ions could diffuse into the interior of tubular structure. PMID:23364917

Chen, Xing; Liu, Zhong-Gang; Zhao, Zhi-Qiang; Liu, Jin-Huai; Huang, Xing-Jiu

2013-07-01

11

The Effect of Magnesium Oxide Supplementation to Aluminum Oxide Slip on the Jointing of Aluminum Oxide Bars  

Microsoft Academic Search

® Alumina. Jointed In-Ceram ® Alumina bars with In-Ceram ® Alumina slips con- taining 0-1.0 mass% MgO were examined by a three-point bending test. Joint-free bars were also tested as controls. Fracture surfaces were evaluated by scanning electron microscopy. In addition, linear shrinkage and fracture toughness were assessed. The 0.3 mass% MgO group showed the highest flexural strength among the

Tetsurou ODATSU; Takashi SAWASE; Kohji KAMADA; Yohsuke TAIRA; Takanobu SHIRAISHI; Mitsuru ATSUTA

2008-01-01

12

Numerical studies of an eccentric tube-in-tube helically coiled heat exchanger for IHEP-ADS helium purification system  

E-print Network

The tube-in-tube helically coiled (TTHC) heat exchanger is preferred in the purifier of IHEP-ADS helium purification system. The position of an internal tube is usually eccentric in a TTHC heat exchanger in practice, while most TTHC heat exchangers in the literature studied are concentric. In this paper, TTHC heat exchangers with different eccentricity ratios are numerically studied for turbulent flow and heat transfer characteristics under different flow rates. The fluid considered is helium at the pressure of 20Mpa, with temperature dependent thermo-physical properties for the inner tube and the annulus. The inner Nusselt number between the concentric and eccentric TTHC heat exchangers are compared, so is the annulus Nusselt number. The results show that with the eccentricity increasing, the annulus Nusselt number increases substantially. According to the numerical data, new empirical correlations of Nusselt number as a function of Reynolds number and eccentricity for the inner tube and the annulus are pres...

Zhang, Jianqin

2014-01-01

13

Flow synthesis using gaseous ammonia in a Teflon AF-2400 tube-in-tube reactor: Paal-Knorr pyrrole formation and gas concentration measurement by inline flow titration.  

PubMed

Using a simple and accessible Teflon AF-2400 based tube-in-tube reactor, a series of pyrroles were synthesised in flow using the Paal-Knorr reaction of 1,4-diketones with gaseous ammonia. An inline flow titration technique allowed measurement of the ammonia concentration and its relationship to residence time and temperature. PMID:22532036

Cranwell, Philippa B; O'Brien, Matthew; Browne, Duncan L; Koos, Peter; Polyzos, Anastasios; Peña-López, Miguel; Ley, Steven V

2012-08-14

14

Analysis of load-slip characteristics of nailed wood joints: application of a two-dimensional geometric nonlinear analysis  

Microsoft Academic Search

We used a two-dimensional finite element method to analyze the load-slip characteristics of nailed wooden joints sheathed with a panel. We used tests of nail bending, nail shank embedment in a wood or a panel, nail-head embedment in a face of a panel, nail withdrawing from a wood, friction between a wood and a panel, and initial axial forces of

Nobuo Nishiyama; Naoto Ando

2003-01-01

15

Ozonation of azo dye Acid Red 14 in a microporous tube-in-tube microchannel reactor: decolorization and mechanism.  

PubMed

The ozonation of synthetic wastewater containing azo dye Acid Red 14 (AR 14) was investigated in a high-throughput microporous tube-in-tube microchannel reactor. The effects of design and operating parameters such as micropore size, annular channel width, liquid volumetric flow rate, ozone-containing gas volumetric flow rate, initial pH of the solution and initial AR 14 concentration on decolorization efficiency and ozone utilization efficiency were studied with the aim to optimize the operation conditions. An increase of the ozone-containing gas or liquid flow rate could greatly intensify the gas-liquid mass transfer. Reducing the micropore size and the annular channel width led to a higher mass transfer rate and was beneficial to decolorization. Decolorization efficiency increased with an increasing ozone-containing gas volumetric flow rate, as well as a decreasing liquid volumetric flow rate and initial AR 14 concentration. The optimum initial pH for AR 14 ozonation was determined as 9.0. The degradation kinetics was observed to be a pseudo-first-order reaction with respect to AR 14 concentration. The difference between the decolorization and COD removal efficiency indicated that many intermediates existed in AR 14 ozonation. The formation of six organic intermediates during ozonation was detected by GC/MS, while the concentration of nitrate and sulfate ions was determined by ion chromatography. The possible degradation mechanism of AR 14 in aqueous solution was proposed. PMID:22704973

Gao, Meiping; Zeng, Zequan; Sun, Baochang; Zou, Haikui; Chen, Jianfeng; Shao, Lei

2012-09-01

16

Evaporation heat transfer and pressure drop of HFC134a in a helically coiled concentric tube-in-tube heat exchanger  

Microsoft Academic Search

The two-phase heat transfer coefficient and pressure drop of HFC-134a during evaporation inside a smooth helically coiled concentric tube-in-tube heat exchanger are experimentally investigated. The test section is a 5.786-m long helically coiled tube with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tube is made from copper tubing of 9.52mm outer diameter

Somchai Wongwises; Maitree Polsongkram

2006-01-01

17

Condensation heat transfer and pressure drop of HFC134a in a helically coiled concentric tube-in-tube heat exchanger  

Microsoft Academic Search

The two-phase heat transfer coefficient and pressure drop of pure HFC-134a condensing inside a smooth helically coiled concentric tube-in-tube heat exchanger are experimentally investigated. The test section is a 5.786m long helically coiled double tube with refrigerant flowing in the inner tube and cooling water flowing in the annulus. The inner tube is made from smooth copper tubing of 9.52mm

Somchai Wongwises; Maitree Polsongkram

2006-01-01

18

Study on the overall heat transfer coefficient for the tube-in-tube heat exchanger used in mixed-gases coolers  

Microsoft Academic Search

In this paper, an experimental set up is established to investigate the behavior of the heat exchanger with multi-components mixtures based on a real mixture refrigeration system. Two tube-in-tube heat exchangers with different configurations are tested extensively with different mixtures operating at three typical temperature ranges, such as 80 K–100 K, 120 K–150 K, and 180 K–200 K temperature ranges.

M. Q. Gong; J. F. Wu; E. C. Luo; Y. F. Qi; Q. G. Hu; Y. Zhou

2002-01-01

19

Study on the overall heat transfer coefficient for the tube-in-tube heat exchanger used in mixed-gases coolers  

Microsoft Academic Search

In this paper, an experimental set up is established to investigate the behavior of the heat exchanger with multi-components mixtures based on a real mixture refrigeration system. Two tube-in-tube heat exchangers with different configurations are tested extensively with different mixtures operating at three typical temperature ranges, such as 80 K-100 K, 120 K-150 K, and 180 K-200 K temperature ranges.

M. Q. Gong; J. F. Wu; E. C. Luo; Y. F. Qi; Q. G. Hu; Y. Zhou

2002-01-01

20

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

21

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

Microsoft Academic Search

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

Kenji Satake

1993-01-01

22

Slip Distributions Of The 2004 Off Kii-peninsula Earthquakes (Mw 7.3, 7.5) Estimated By Joint Inversion Using Tsunami Waveforms And Crustal Deformation Data  

NASA Astrophysics Data System (ADS)

On 5 September 2004, two earthquakes (Mw 7.3, 7.5) occurred at off the Kii-peninsula. Both earthquakes generated a large tsunami recorded at tide gauges along the Pacific coast of Honshu, ocean bottom pressure gauges and a GPS tsunami gauge. The crustal deformation on land had been observed by the continuous GPS observation system(GEONET) operated by Geographical Survey Institute(GSI), and the ocean bottom crustal deformation near the epicenters had been observed by the Observation System for Ocean Bottom Crustal Deformation operated by Nagoya University (http://www.seis.nagoya-u.ac.jp/~tadokoro/obcd.gaiyou.html). In this study, we estimated the slip distribution of two events by joint inversion of tsunami waveforms and horizontal crustal deformation data. We used tsunami waveforms observed at 6 tide gauge stations, 7 ocean bottom pressure gauges, a GPS tsunami gauge. We also used horizontal crustal deformation data observed at 151 GPS sites and one Observation System for Ocean Bottom Crustal Deformation. For this earthquake, two different fault models, fault model1 by Yamanaka (http://www.eri.u-tokyo.ac.jp/sanchu/Seismo_Note/2004/EIC153.html) and fault model2 by Yagi (http://iisee.kenken.go.jp/staff/yagi/eq/Japan20 040905/Japan20040905_1-j.html), are suggested using seismic waveform analysis. The fault models we used in this study are referred to these two fault models. The slip distribution of two earthquakes were estimated by using tsunami waveforms from two earthquakes and the coseismic horizontal displacement data which include the displacements of both earthquakes. The observed tsunami waveforms were equally explained by the synthetic waveforms calculated from fault model1 and fault model2. However, the observed crustal deformation data are well explained by the computed data from the fault model2, but not by those from the fault model1. The slip distribution using the fault model2 estimated by joint inversion shows that the maximum slip amount of the first event is 1.3m, that of the second event is 3.2m. The seismic moments of the first and second events are 5.0x1019[Nm](Mw=7.1), 1.7x1020[Nm](Mw=7.4) respectively.

Kusunose, T.; Tanioka, Y.; Satake, K.; Baba, T.; Hirata, K.; Iwasaki, S.; Kato, T.; Koshimura, S.; Hasegawa, Y.; Imakiire, T.

2005-12-01

23

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

NASA Astrophysics Data System (ADS)

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

Bird, P.

2008-12-01

24

Joints  

NSDL National Science Digital Library

Hinge joints move only in one direction, ball-and-socket joints are free to rotate in all directions, and gliding joints are able to move forward, backward, and side to side, but do not rotate freely.

Olivia Worland (Purdue University; Biological Sciences)

2008-06-06

25

Joint Determination of Slip and Stress Drop in a Bayesian Inversion Approach: A Case Study for the 2010 M8.8 Maule Earthquake  

NASA Astrophysics Data System (ADS)

Stress drop is a key factor in earthquake mechanics and engineering seismology. However, stress drop calculations based on fault slip can be significantly biased, particularly due to subjectively determined smoothing conditions in the traditional least-square slip inversion. In this study, we introduce a mechanically constrained Bayesian approach to simultaneously invert for fault slip and stress drop based on geodetic measurements. A Gaussian distribution for stress drop is implemented in the inversion as a prior. We have done several synthetic tests to evaluate the stability and reliability of the inversion approach, considering different fault discretization, fault geometries, utilized datasets, and variability of the slip direction, respectively. We finally apply the approach to the 2010 M8.8 Maule earthquake and invert for the coseismic slip and stress drop simultaneously. Two fault geometries from the literature are tested. Our results indicate that the derived slip models based on both fault geometries are similar, showing major slip north of the hypocenter and relatively weak slip in the south, as indicated in the slip models of other studies. The derived mean stress drop is 5-6 MPa, which is close to the stress drop of ~7 MPa that was independently determined according to force balance in this region Luttrell et al. (J Geophys Res, 2011). These findings indicate that stress drop values can be consistently extracted from geodetic data.

Wang, Lifeng; Zöller, Gert; Hainzl, Sebastian

2015-02-01

26

Slip stacking  

SciTech Connect

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

Kiyomi Koba and James Steimel

2002-09-19

27

[Slipped capital femoral epiphysis].  

PubMed

Slipped capital femoral epiphysis (SCFE) is a common hip disorder in adolescence and should be diagnosed and treated surgically as soon as possible. The etiology, biomechanical, biochemical and hereditary factors are still under investigation. The classification of SCFE is based on the acuteness, clinical and radiomorphological findings. Avascular necrosis of the epiphysis (AVN) and chondrolysis occur more often in operated than in non-operated patients. Medium and long-term sequelae of SCFE are loss of function and degenerative joint disease due to femoroacetabular impingement (FAI) or consequences from complications such as AVN and chondrolysis. For mild slips the long-term prognosis is better than for moderate or severe slips. Higher grade unstable SCFE may benefit from reduction while in chronic slips corrective osteotomy may be indicated. Traditional osteotomy procedures, such as Imhäuser or Southwick intertrochanteric osteotomy are safe procedures but correct the deformity distant from the site of the deformity. The surgical dislocation with modified Dunn osteotomy according to Ganz allows the preparation of an extended retinacular soft tissue flap and offers an extensive subperiosteal exposure of the circumference of the femoral neck before reducing the slipped epiphysis anatomically. In cases of FAI due to mild deformities restoration of the head-neck offset via hip arthroscopy or surgical dislocation should be considered before higher grade cartilage damage occurs. PMID:20830467

Zilkens, C; Jäger, M; Bittersohl, B; Kim, Y-J; Millis, M B; Krauspe, R

2010-10-01

28

Partitioning Slip  

NSDL National Science Digital Library

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

29

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2014 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2014-01-01

30

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2012 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2012-01-01

31

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2010 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2010-01-01

32

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2010 CFR

...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 have provision for...

2010-01-01

33

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2012 CFR

...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 have provision for...

2012-01-01

34

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2011 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2011-01-01

35

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2013 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2013-01-01

36

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2013 CFR

...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 have provision for...

2013-01-01

37

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2011 CFR

...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 have provision for...

2011-01-01

38

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2014 CFR

...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 have provision for...

2014-01-01

39

Tube-in-tube thermophotovoltaic generator  

DOEpatents

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

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

1998-06-30

40

Tube-in-tube thermophotovoltaic generator  

DOEpatents

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

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

1998-01-01

41

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)

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).

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

2008-01-01

42

Electro-optical hybrid slip ring  

Microsoft Academic Search

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

En Hong

2005-01-01

43

Electro-optical hybrid slip ring  

NASA Astrophysics Data System (ADS)

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

Hong, En

2005-11-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

45

Stress coupling tested in fault slip inversion  

NASA Astrophysics Data System (ADS)

The seismic cycle includes the interseismic, coseismic and postseismic phase. The large earthquakes release the interseismically accumulated stress on the fault, and are followed by stress relaxation processes in the postseismic phase. Based on the geodetic measurements, the stress coupling in the seismic cycle can be investigated by interseismic slip deficit, coseismic rupture and postseismic slip distributions. However, it is well-known that the fault slip inversions based only on the measurements on the surface are typically non-unique and subject to large uncertainties. In this study, we firstly assume the existence of stress coupling in the seismic cycle, and then do the stress constrained joint inversion in Bayesian approach (Wang et al., 2012) to invert either for (1) interseismic slip deficit and coseismic slip or for (2) coseismic slip and postseismic creep. Based on the modeling results, we evaluate if the assumed stress coupling is reasonable and if the stress coupling is able to be reflected from the available geodetic measurements. We take the earthquakes in the regions with well-instrumented network (such as the 2004 M6.0 Parkfield earthquake, the 2010 M8.7 earthquake and the 2011 M9.1 Tohoku-Oki earthquake) as study cases.

Wang, L.; Hainzl, S.; Zoeller, G.

2013-12-01

46

Economical Joint for Truss Structures  

NASA Technical Reports Server (NTRS)

Mass-produced flat parts easily assembled. Joint for three-dimensional truss made of simple die-cutplates and inexpensive fasteners. Each truss joint consists of two identical interlocking plates bolted, welded, or glued together. Truss struts bolted to joint through holes in plate. Alternatively, ends of struts forked so that they slip over plates and fastened to them by bolts or pins.

Moore, Carleton J.

1987-01-01

47

Nailed wood joints under combined loading  

Microsoft Academic Search

A new testing apparatus was designed and a test method developed to enable the application of axial loads, lateral loads, and controlled ratios of axial to lateral loads to nailed wood joints. The effect of axial load components on ultimate lateral load, joint deformations and several slip moduli were evaluated. These load-slip parameters were determined for three species of wood,

A. Louis DeBonis; J. Bodig

1975-01-01

48

Earthquake Slip Classroom Exercise  

NSDL National Science Digital Library

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

2011-01-10

49

Well slip assemblies  

SciTech Connect

There is disclosed an hydraulically set well packer wherein sleeves carried about a tubular member which is connected as part of a tubing string are adapted to be moved from axially extended to axially retracted position in order to expand packing and slip elements carried about one of the sleeves into engagement with the well bore in which the string is disposed. The packer also includes means which forms an atmospheric chamber including a piston on one of the sleeves, and a means for locking the sleeves in retracted position is disposed within such chamber. The slip assembly carried by the packer includes upper and lower bowls and upper and lower sets of interconnected slips which are carried by the bowls for sliding thereover between radially contracted and expanded positions in response to movement of the slip bowls toward and away from one another as the sleeves move between extended and retracted positions.

Akkerman, N.H.

1984-04-03

50

Slipped Capital Femoral Epiphysis  

MedlinePLUS

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

51

SlipKnot Home Page  

NSDL National Science Digital Library

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

52

The frictional properties of joints in rock  

Microsoft Academic Search

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

J. C. Jaeger

1959-01-01

53

Slip Rates on young faults  

NSDL National Science Digital Library

Students use measured ages and offset of quaternary surfaces to determine vertical slip rates of a young fault. Students then must determine if vertical slip rates have varied significantly through time.

Audrey Huerta

54

Limited slip differential  

Microsoft Academic Search

This patent describes a limited slip differential for a vehicle comprising a casing adapted to be driven; a pair of side gears; a pinion gear retained within the casing and engaging the side gears to form a differential gear mechanism; a pinion mate shaft supporting pinion gear and having a cam portion; a pair of pressure rings retained within the

K. Ozaki; S. Torii; T. Jindo; T. Imaseki

1987-01-01

55

Well slip assemblies  

Microsoft Academic Search

There is disclosed an hydraulically set well packer wherein sleeves carried about a tubular member which is connected as part of a tubing string are adapted to be moved from axially extended to axially retracted position in order to expand packing and slip elements carried about one of the sleeves into engagement with the well bore in which the string

Akkerman

1984-01-01

56

Evaluating relaxation of high-strength bolts by parameters on slip faying surfaces of bolted connections  

Microsoft Academic Search

The clamping force of a high-strength bolt reduces within a certain time period after the initial clamping force. When special\\u000a treatments are used on a faying surface, the clamping force is relaxed severely. Tests were conducted for slip critical joints\\u000a subjected to various faying surface parameters. Relaxation occurred for slip resistant joints with an uncoated surface that\\u000a had been shot-blasted,

Hwan-Seon Nah; Hyeon-Ju Lee; Kang-Seok Kim; Jin-Ho Kim; Woo-Bum Kim

2010-01-01

57

Low-Friction Joint for Robot Fingers  

NASA Technical Reports Server (NTRS)

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

Ruoff, C. F.

1985-01-01

58

Slip partitioning by elastoplastic propagation of oblique slip at depth.  

PubMed

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

Bowman, David; King, Geoffrey; Tapponnier, Paul

2003-05-16

59

Universal behavior in ideal slip  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

60

SlipChip†  

PubMed Central

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

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

2009-01-01

61

Mechanism of slip and twinning  

NASA Technical Reports Server (NTRS)

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

Rastani, Mansur

1992-01-01

62

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

PubMed

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

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

2013-01-01

63

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

PubMed Central

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

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

2013-01-01

64

Suppression of strike-slip fault systems  

NASA Astrophysics Data System (ADS)

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

Curren, I. S.

2012-12-01

65

Seismic slip of oceanic strike-slip earthquakes  

NASA Astrophysics Data System (ADS)

We investigate the controls on seismic slip in oceanic lithosphere through teleseismic body-wave modeling of oceanic strike-slip earthquakes to determine fault plane as well as the depth distribution of seismic rupture. At first-order we can combine modern constraints on oceanic transform faults of slip rate, cumulative seismic moment and improved centroid depths to reveal a disparity of strain release that must be accommodated with aseismic slip (Brune, 1968). We seek to attain a higher order of understanding the distribution and relationship between aseismic and seismically slipping areas of oceanic strike-slip faults. Examining the seismic slip of large earthquakes on these faults can help to constrain properties of oceanic lithosphere and determine if the thickness of the seismogenic zone is controlled by temperature, composition, geometry or a combination of attributes. Over 45 MW ? 7.0 oceanic strike-slip earthquakes have occurred since 1990, with 10 of these in the last two years alone, yet little is known about their depth, rupture pattern and fault orientation. The two largest earthquakes of 2012 occurred on April 11th and were both intraplate oceanic strike-slip earthquakes; they appear to have ruptured multiple orthogonally oriented faults with some rupture extending to unexpectedly great depths. The depth of oceanic strike-slip earthquakes is difficult to constrain, particularly in the shallow crust; this study uses teleseismic body-waves P and S as well as depth phases pP, sP and water multiples to enhance our precision. Earthquakes off the coast of Sumatra, California, Alaska and Western Australia as well as near the South Sandwich and Santa Cruz Islands are carefully repicked for phase arrivals and polarities. We calculate moment tensors for magnitude 6.0 ? MW ? 8.0 earthquakes in these areas with particular attention paid to the highly nodal first arriving P phase. For events of magnitude 7.0 ? MW ? 8.0 since 1990 we perform finite-fault slip inversions on the two conjugate planes to identify which faults ruptured during each event. These large earthquakes rupture a broad range of oceanic lithosphere aged 0 to 70 My and above (Müller et al, 2008) and occur in both interplate transform and intraplate tectonic settings. It is widely accepted that temperature has significant control on the depth extent of seismic rupture, but with an extensive sampling of oceanic strike-slip earthquakes we can determine if other lithospheric properties hold an observable role to further explain rupture complexity with depth and along strike.

Aderhold, K.; Abercrombie, R. E.; Antolik, M. S.

2013-12-01

66

Detecting slipping-like perturbations by using adaptive oscillators.  

PubMed

This study introduces a novel algorithm to detect unexpected slipping-like perturbations based on the comparison between actual leg joint angles and those predicted by a pool of adaptive oscillators. The approach grounds on the hypothesis that during postural transitions, the difference between these datasets diverges and can early signal that the dynamic balance is challenged. To test this hypothesis, leg joint angles of twelve healthy young participants were recorded while undergoing four different perturbations delivered during steady locomotion. Joint angles were estimated after spanning the whole domain of the adaptive oscillator dynamics. Results confirmed that the implemented strategy allows to early detect a postural transition induced by a slipping-like perturbation: the best performance is represented by a mean detection time ranging between 150 and 250 ms and a low rate (lower than 10%) of false alarms. On the whole, the proposed approach is efficient even if it is based on a quite simple threshold-based algorithm. Moreover, it does not need any falling-based training before being implemented, is not computationally heavy, and is not subject dependent. Finally, since it is based on leg joint angles, it appears well suited to be implemented in lower-limb orthoses/prostheses already equipped with joint position sensors. PMID:25377766

Tropea, Peppino; Vitiello, Nicola; Martelli, Dario; Aprigliano, Federica; Micera, Silvestro; Monaco, Vito

2015-02-01

67

Effects of interlayer slip on multilayered folds  

E-print Network

, this feature usually is not developed, thus geometrical models are commonly used to investigate the kinematics of interlayer slip (de Sitter, 1956; Ramsay, 1967, 1974; Morris, 1967, 1971). The magnitude of slip, determined from these models, increases..., "classical" slip occurs (de Sitter, 1956; Ramsay, 1967, 1974; Norris, 1967), and in each layer bounded by slip surfaces a neutral surface is observed (Bell and Currie, 1964) . Few mathematical studies of interlayer slip have been made. Chapple and Spang...

Casarta, Lawrence Joseph

1980-01-01

68

Flow-induced vibrations-1987  

SciTech Connect

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

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

1987-01-01

69

Velocity slip on curved surfaces.  

PubMed

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. PMID:25353569

Chen, Weikang; Zhang, Rui; Koplik, Joel

2014-02-01

70

Effects of material property variations on slip estimates for subduction interface slow-slip events  

NASA Astrophysics Data System (ADS)

We investigate the influence of elastic heterogeneity on geodetic inversions of slow-slip events by inverting for slip distributions of four events along the Hikurangi Margin, New Zealand. We generate Green's functions using a finite element code in conjunction with a New Zealand-wide seismic velocity model to assign elastic properties. We find that these heterogeneous models typically require ~20% less slip than homogeneous models in cases where the slip is deep or there is reasonable geodetic coverage above the slipping region. In cases where the slip is shallow (and mostly offshore) and there is little geodetic coverage directly above the slipping region, the heterogeneous models can predict significantly larger amounts of slip (42% in our study). These changes in the predicted amounts of slip have important implications for quantifying slip budgets accommodated by slow slip at subduction zones worldwide.

Williams, Charles A.; Wallace, Laura M.

2015-02-01

71

A prospective review of open central slip laceration repair and rehabilitation.  

PubMed

A prospective review was carried out to evaluate the outcome of surgically repaired open central slip (zone III) injuries which were treated with 3 weeks of proximal interphalangeal joint immobilization within a cylinder splint and then with 3 weeks of controlled mobilization within a Capener coil splint. Thirty-one fingers in 27 patients were assessed by the same independent therapist. All fingers achieved an excellent or good recovery with a mean proximal interphalangeal joint flexion of 94 degrees (range 70-110 degrees) and a mean distal interphalangeal joint flexion of 57 degrees (range 30-81 degrees). Extension deficits of the proximal interphalangeal joint were noted in five fingers (mean 6 degrees, range 3-15 degrees). The results show that a combination of immobilization and controlled mobilization is an effective rehabilitation regime for surgically repaired open central slip injuries. PMID:12475509

Pratt, A L; Burr, N; Grobbelaar, A O

2002-12-01

72

Comparison of proximal turndown of central slip combined with suture of lateral bands versus free tendon grafting for central slip reconstruction after an open finger injury.  

PubMed

We randomized patients with open finger injury and central slip insertion defects into a proximal turn-down group (final n = 28) and a palmaris longus tendon graft group (final n = 20). In the proximal turn-down group, the dorsal central slip of the extensor tendon in the proximal phalanx was split, leaving it attached distally. We turned the strip from proximal to distal and fixed it using the distal joint capsule of the proximal interphalangeal joint as the distal insertion of reconstruction, and the extended central slips were then fixed to the middle phalanx. The dorsal traumatic central slip was stitched with lateral bands using 2-0 suture to form a new conjoint tendon. The injured central slip in the comparison group was sutured using autogenous palmaris longus tendon and fixed in drilled holes in the middle phalanx. Outcomes assessment was performed according to Dargan's criteria during postoperative follow-up. Motion range in the proximal turndown group was significantly greater than in the graft group (p < 0.05). We observed no boutonniere deformity in both the proximal turndown and graft group. PMID:24873096

Li, Ying; Ding, Aizhong; He, Zhimin; Xue, Feng

2014-03-01

73

Slip rate and tremor genesis in Cascadia  

USGS Publications Warehouse

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

Wech, Aaron G.; Bartlow, Noel M.

2014-01-01

74

Bulk Metallic Glasses Deform via Slip Avalanches  

E-print Network

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.

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

2013-12-21

75

CAPSULAR TISSUES OF THE PROXIMAL INTERPHALANGEAL JOINT: NORMAL COMPOSITION AND EFFECTS OF DUPUYTREN'S DISEASE AND RHEUMATOID ARTHRITIS  

Microsoft Academic Search

Three fibrocartilages associated with the proximal interphalangeal joint are described—at the attachment of the central slip to bone, within the slip where it passes over the joint, and the volar plate. Material was obtained at surgery following trauma, Dupuytren's disease and rheumatoid arthritis. The fibrocartilages were structurally distinct and immunolabelled differently with monoclonal antibodies to extracellular matrix components. All fibrocartilages

M. BENJAMIN; J. R. RALPHS; M. SHIBU; M. IRWIN

1993-01-01

76

What Is an Earthquake?: Oblique Slip  

NSDL National Science Digital Library

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

77

Slip instability and state variable friction laws  

Microsoft Academic Search

The dependence of the friction on slip history is described by an experimentally motivated constitutive law where the friction is dependent on slip rate and state variables. The state variables are defined macroscopically by evolution equations for their rates of change in terms of their present values and slip rate. Experiments may strongly suggest that one state variables is adequate

Andy Ruina

1983-01-01

78

Avoiding stick-slip in position and force control through feedback  

Microsoft Academic Search

The avoidance of stick-slip motion at low velocities through feedback control is discussed. Simplified single-joint robot models are derived for position and force control. It is shown that both models can be represented by the same differential equation. Most prior work in control used friction models which depend only on the current value of velocity. This type of analysis indicates

Pierre E. Dupont

1991-01-01

79

Reliable slip-on vacuum coupling for low-temperature apparatus  

NASA Astrophysics Data System (ADS)

A reliable slip-on vacuum coupling scheme for low-temperature applications is described. The novel aspect of this concept is the use of silicone fluid as the sealing agent. The stem and coupling joint described has performed without failure at room temperature, immersed in normal 4He and in superfluid 4He.

Stasiak, J. W.; Guernsey, R. W., Jr.

1984-09-01

80

Slipping properties of ceramic tiles / Quantification of slip resistance  

NASA Astrophysics Data System (ADS)

Regarding the research and application of ceramic tiles there is a great importance of defining precisely the interaction and friction between surfaces. Measuring slip resistance of floor coverings is a complex problem; slipperiness is always interpreted relatively. In the lack of a consistent and clear EU standard, it is practical to use more method in combination. It is necessary to examine the structure of materials in order to get adequate correlation. That is why measuring techniques of surface roughness, an important contributor to slip resistance and cleaning, is fundamental in the research. By comparing the obtained test results, relationship between individual methods of analysis and values may be determined and based on these information recommendations shall be prepared concerning the selection and application of tiles.

Terjek, Anita

2013-12-01

81

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

PubMed Central

The disease-associated expansion of (CTG)·(CAG) repeats is likely to involve slipped-strand DNAs. There are two types of slipped DNAs (S-DNAs): slipped homoduplex S-DNAs are formed between two strands having the same number of repeats; and heteroduplex slipped intermediates (SI-DNAs) are formed between two strands having different numbers of repeats. We present the first characterization of S-DNAs formed by disease-relevant lengths of (CTG)·(CAG) repeats which contained all predicted components including slipped-out repeats and slip-out junctions, where two arms of the three-way junction were composed of complementary paired repeats. In S-DNAs multiple short slip-outs of CTG or CAG repeats occurred throughout the repeat tract. Strikingly, in SI-DNAs most of the excess repeats slipped-out at preferred locations along the fully base-paired Watson–Crick duplex, forming defined three-way slip-out junctions. Unexpectedly, slipped-out CAG and slipped-out CTG repeats were predominantly in the random-coil and hairpin conformations, respectively. Both the junctions and the slip-outs could be recognized by DNA metabolizing proteins: only the strand with the excess repeats was hypersensitive to cleavage by the junction-specific T7 endonuclease I, while slipped-out CAG was preferentially bound by single-strand binding protein. An excellent correlation was observed for the size of the slip-outs in S-DNAs and SI-DNAs with the size of the tract length changes observed in quiescent and proliferating tissues of affected patients—suggesting that S-DNAs and SI-DNAs are mutagenic intermediates in those tissues, occurring during error-prone DNA metabolism and replication fork errors. PMID:12384601

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

2002-01-01

82

Hip joints  

NSDL National Science Digital Library

The human hips are an example of a ball-and-socket joint. Ball-and-socket joints have the ability to rotate in a circular motion. The joint where the arm connects to the shoulder is also a type of ball-and-socket joint.

Connie Raab (National Institutes of Health; )

2006-05-17

83

Molecular Scale Simulation of Homopolymer Wall Slip  

NASA Astrophysics Data System (ADS)

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.

Dorgan, John R.; Rorrer, Nicholas A.

2013-04-01

84

Molecular scale simulation of homopolymer wall slip.  

PubMed

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

Dorgan, John R; Rorrer, Nicholas A

2013-04-26

85

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

Microsoft Academic Search

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

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

1997-01-01

86

How do Faults Slip: Earthquakes versus Episodic Tremor and Slip  

NSDL National Science Digital Library

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

Mike Brudzinski

87

Slow slip events in Guerrero, Mexico, and consequences on strain accumulation over the past 15 years.  

NASA Astrophysics Data System (ADS)

Continuous Global Positioning System (cGPS) time series in Guerrero, Mexico, reveal the widespread existence of large Slow Slip Events (SSEs) at the boundary between the Cocos and North American plates. The existence of these SSEs asks the question of how seismic and aseismic slips complement each other in subduction zones. We examined the last three SSEs that occurred in 2001/2002, 2006 and 2009/2010, and their impact on the strain accumulation along the Guerrero subduction margin. We use continuous cGPS time series and InSAR images to evaluate the surface displacement during SSEs and inter-SSE periods. The slip distributions on the plate interface associated with each SSE, as well as the inter-SSE (short-term) coupling rates are evaluated by inverting these surface displacements. Our results reveal that the three analyzed SSEs have equivalent moment magnitudes of around 7.5 and their lateral extension is variable.The slip distributions for the three SSEs show that in the Guerrero gap area, the slow slip occurs at shallower depth (updip limit around 15-20 km) than in surrounding regions. The InSAR data provide additional information for the 2006 SSE. The joint inversion of InSAR and cGPS data confirms the lateral variation of the slip distribution along the trench, with shallower slip in the Guerrero seismic gap, west of Acapulco, and deeper slip further east. Inversion of inter-SSE displacement rates reveal that during the inter-SSE time intervals, the interplate coupling is high in the area where the slow slip subsequently occurs. Over a 12 year period, corresponding to three cycles of SSEs, our results reveal that the accumulated slip deficit in the Guerrero gap area is only ¼ of the slip deficit accumulated on both sides of the gap. Moreover, the regions of large slip deficit coincide with the rupture areas of recent large earthquakes. We conclude that the SSEs account for a major portion of the overall moment release budget in the Guerrero gap. If large subduction thrust earthquakes occur in the Guerrero gap, their recurrence time is probably increased compared to adjacent regions.

Radiguet, M.; Cotton, F.; Cavalié, O.; Pathier, E.; Kostoglodov, V.; Vergnolle, M.; Campillo, M.; Walpersdorf, A.; Cotte, N.; Santiago, J.; Franco, S.

2012-12-01

88

Multicycle slip distribution along a laboratory fault  

USGS Publications Warehouse

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

Chi-Yu, King

1991-01-01

89

Process for slip casting textured tubular structures  

DOEpatents

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

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

2002-01-01

90

Animations of Episodic Tremor and Slip  

NSDL National Science Digital Library

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

Shelley Olds

91

Isothermal slip flow over curved surfaces  

Microsoft Academic Search

It has long been recognised that the no-slip-boundary condition employed in the Navier–Stokes equations can only be applied when the Knudsen number, Kn?10?3. If the Knudsen number is increased beyond this value, rarefaction effects start to influence the flow and the molecular collision frequency per unit area becomes too small to maintain the no-slip-boundary condition. Unfortunately, Maxwell's famous slip equation

R. W. Barber; Y. Sun; X. J. Gu; D. R. Emerson

2004-01-01

92

Learning to predict slip for ground robots  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

93

Slip asymmetry in the molecular crystal cyclotrimethylenetrinitramine  

NASA Astrophysics Data System (ADS)

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

Mathew, N.; Picu, R. C.

2013-09-01

94

Boundary slip dependency on surface stiffness.  

PubMed

The paper investigates the effects of surface stiffness on the slip process aiming to obtain a better insight of the momentum transfer at nanoscale. The surface stiffness is modeled through the stiffness, ?, of spring potentials, which are employed to construct the thermal walls. It is shown that variations of stiffness, ?, influence the slip mechanism either toward slip or stick conditions. Increasing the values of ? alters the oscillation frequency and the mean displacement of the wall particles toward higher and lower values, respectively. Our results suggest that the amount of slip produced as a function of stiffness follows a common pattern that can be modeled through a fifth-order polynomial function. PMID:20866421

Asproulis, Nikolaos; Drikakis, Dimitris

2010-06-01

95

Development of a liquid metal slip ring  

NASA Technical Reports Server (NTRS)

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.

Weinberger, S. M.

1972-01-01

96

Derivation of generalized Maxwell velocity slip model  

NASA Astrophysics Data System (ADS)

Based on the conservation of momentum and energy fluxes in the Knudsen layer, a generalized Maxwell velocity slip boundary model is derived in detail using the velocity distribution function from the Grad thirteen moment approximation. The study shows that the generalized Maxwell velocity slip boundary model has the same form as the slip model given by Lockerby. In addition, it is consistent with the typical Maxwell velocity slip model when the temperature gradient along the surface and the normal velocity of gas flow are neglected.

Yang, Qin; Liu, Yulu; Zhang, Haijun; Zuo, Chuncheng

2014-12-01

97

Bulk metallic glasses deform via slip avalanches.  

PubMed

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

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

2014-04-18

98

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

Microsoft Academic Search

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

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

1996-01-01

99

Slack adjustment for slip system in downhole well apparatus  

Microsoft Academic Search

A well packer having a radially extendable and retractable resilient annular sealing element and slip assembly includes a slack adjusting mechanism for maintaining the cooperating slip cones and slip members in an axially adjusted position to reduce radial play in the slip members when the slip assembly is in the retracted condition. The slack adjusting mechanism includes an internal threaded

H. H. Jr. Fisher

1984-01-01

100

Spacetime correlation of slip and tremor during the 2009 Cascadia slow slip event  

E-print Network

Spacetime correlation of slip and tremor during the 2009 Cascadia slow slip event Noel M. Bartlow,1; accepted 25 August 2011; published 23 September 2011. [1] Episodic Tremor and Slip (ETS), involving transient deformations accompanied by emergent, lowfrequency tremor occurs in subduction zones around

Segall, Paul

101

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

Microsoft Academic Search

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

Garry Rogers; Herb Dragert

2003-01-01

102

Laboratory measurements of frictional slip on interfaces in a polycarbonate rock mass model  

SciTech Connect

The evaluation of the stability of the openings for the Exploratory Studies Facility and a potential repository for high-level nuclear waste at Yucca Mountain, Nevada will require computer codes capable of predicting slip on rock joints resulting from changes in thermal stresses. The geometrical method of analysis of moire fringe analysis was used to evaluate the magnitude and extent of frictional sliding in a layered polycarbonate rock mass model containing a circular hole. Slips were observed in confined zones around the hole and micron resolutions were obtained. Unpredicted and uncontrolled uniform slip of several interfaces in the model were observed giving considerable uncertainty in the boundary conditions of the model, perhaps making detailed comparison with numerical models impossible.

Brown, S.R. [Sandia National Labs., Albuquerque, NM (United States). Geomechanics Dept.

1994-08-01

103

Frictional melting of peridotite and seismic slip  

Microsoft Academic Search

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

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

2009-01-01

104

Preseismic fault slip and earthquake prediction  

Microsoft Academic Search

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

J. H. Dieterich

1978-01-01

105

PC program speeds slip-velocity calculations  

Microsoft Academic Search

A Basic program is presented here to calculate drill cutting slip velocity and transport ratio using Moore's and Chien's correlations. A computer program has been developed for calculating slip velocity from both Chien's and Moore's equations. Because the flow behavior is so complex, observation and experience are often used to determine the lifting ability of the drilling fluid. This usually

M. S. Bizanti; S. Robinson

1988-01-01

106

Dislocation Cross-slip Mechanisms in Aluminum  

NASA Astrophysics Data System (ADS)

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

Xiang, Yang; Jin, Congming; Lu, Gang

2012-02-01

107

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...

108

[Evaporating Droplet and Imaging Slip Flows  

NASA Technical Reports Server (NTRS)

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.

Larson, R. G.

2002-01-01

109

Suppression of strike-slip fault zones by preexisting crustal heterogeneities  

NASA Astrophysics Data System (ADS)

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

Curren, I. S.; Bird, P.

2013-12-01

110

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

USGS Publications Warehouse

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

McGarr, A.; Fletcher, Joe B.

2003-01-01

111

Electrostatic precursors to granular slip events  

PubMed Central

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

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

2012-01-01

112

Stopping stick-slip seismic events?  

NSDL National Science Digital Library

This resource provides an abstract. This study models underground frictional resistance in stick-slip seismic events in order to determine the amount of energy needed to weaken a fault plane enough to initiate ground motion and simulate the speed of the recovery after the pressure subsides. The exact moment the slip began the maximum speed of the ground motion were detected. Results indicate that stick-slip events stop spontaneously when frictional melting begins, suggesting a potential way to stop the seismic events.

Koizumi et al.

113

Slow slip event at Kilauea Volcano  

USGS Publications Warehouse

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

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

2010-01-01

114

Flow and slip transition in nanochannels.  

PubMed

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

Li, Long; Mo, Jingwen; Li, Zhigang

2014-09-01

115

Dynamical stability of slip-stacking particles  

NASA Astrophysics Data System (ADS)

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

Eldred, Jeffrey; Zwaska, Robert

2014-09-01

116

Slip compensation at fault damage zones along earthquake surface ruptures  

NASA Astrophysics Data System (ADS)

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

Choi, J.; Kim, Y.

2013-12-01

117

Is slow slip in Cascadia tidally modulated?  

NASA Astrophysics Data System (ADS)

Several studies have shown that the seismic tremor in episodic tremor and slip is tidally modulated, suggesting a strong sensitivity to the rather small tidal stresses. We address whether the slip is also tidally modulated by examining data from six borehole strainmeters in northwest Washington and southern Vancouver Island. We use the processed data provided by Plate Boundary Observatory (PBO), which is resampled to 5-minute intervals. However, we recompute empirical corrections for tides, a long-term linear trend, and barometric pressure in the 50 days surrounding each slow slip event. We then fit sinusoids at the tidal periods to the processed data as proxies for the tidally modulated component of slip, along with a linear trend as a proxy for the net strain in the slow slip. The data are too noisy to allow detection any tidal modulation using only a single event and station. We therefore simultaneously fit data from multiple stations and from three slow slip events since 2007. This assumes that the phase of the tides at the slipping regions detected by all stations is the same and that the phase of the fault response to the tidal stress is constant. Combining the stations and events both reduces the noise at the tidal periods and creates a longer time series, which allows us to separate energy at the different tidal frequencies. We find significant tidal signals at the 12.4 and 25.8-hour periods which differ from zero at the 1.5 to 2-sigma level. Errors are estimated by bootstrapping the slow slip strain and by considering the tidal signal at times before the slow slip event. The 12.4 and 25.8-hour sinusoids have amplitudes of 23 (10-40 at 2-sigma) and 15 (0-30 at 2-sigma) percent of the maximum amplitude that does not allow the slow slip strain signal to change sign, where the mean strain rate is estimated from the linear trends fit to the slow slip data. In terms of slip rate, the sinusoids at each period could then modulate the slip rate 23 and 15 percent above and below the average. These amplitudes are interesting from a modeling standpoint because they may distinguish between models of slow slip and tremor that have almost all their slip in one part of the tidal cycle and those where the slip rate is more gradually modulated by the stress. Comparison with an existing tremor catalog (Wech and Creager, 2008) reveals that the observed maximum strain rate at the borehole, interpreted to be in phase with the max slip rate on the fault, coincides with the highest rate of tremor within the 12.4 hour period. However, variation at the 25.8-hour period is not evident in the tremor data.

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

2009-12-01

118

3-D Discrete Element Simulation of Strike Slip Faulting  

NASA Astrophysics Data System (ADS)

Recent progress of the X-ray Computed Tomography(X-rayCT) enables us to observe not only the surface but also the inside of geomaterials with a certain level of resolution. X-rayCT was employed in a series of experiments on sand box to visualize the faulting mechanism. A three-dimensional discrete element simulation was performed in order to figure out not only the strain distribution but also the stress distribution during the process of strike slip faulting. In this simulation, a rectangular sand box made of a rigid basement and rigid lateral walls is modeled with 129300 particles. The Discrete Element Method(DEM), widely used in the field of soil mechanics, is a numerical simulation technique that solves an assembly of frictional granular bodies by means of pursuing a behavior of interacting particle governed by Newton's laws of motion. The strike slip faulting analysis successfully simulated the sequential Reidel shear development from basement and computed the stress distribution produced by shearing. A zone of intensive shear stress developed adjacent to the Reidel shear plane joint at the pre-peak stage of boundary shear stress time history. After the peak stage of boundary shear stress, the shapes of histogram of the second stress invariant kept almost unchanged, then the boundary shear stress reached the residual strength and a lumped shear band appeared near the center of the model.

Saomoto, H.; Yoshimi, M.; Kunimatsu, S.

2004-12-01

119

Critical Slip-Weakening Distance Inferred From Slip-Velocity Functions on Earthquake Faults  

Microsoft Academic Search

We estimate the critical slip-weakening distance on earthquake faults by using a new approach based on a relation between the breakdown time of shear stress, the time of peak slip-velocity, and the prescribed slip-weakening distance, which is independent of the fracture energy or radiated seismic energy. This method has been applied to the 2000 Tottori earthquakes in western Japan. We

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

120

Slip-stream corrections performance computation  

NASA Technical Reports Server (NTRS)

This report is an analysis of experiments performed by Eiffel on the air velocity in slip stream of a propeller, and also includes a theoretical discussion of the magnitude of the velocity in different propellers.

Warner, Edward P

1920-01-01

121

Beam loading compensation for slip stacking  

SciTech Connect

This paper discusses the beam loading compensation requirements to make slip stacking practical in the Fermilab main injector. It also discusses some of the current plans for meeting these requirements with a digital, direct RF feedback system.

James Steimel; Tim Berenc; Claudio Rivetta

2003-06-04

122

Beyond the no-slip boundary condition  

E-print Network

This paper offers a simple macroscopic approach to the question of the slip boundary condition to be imposed upon the tangential component of the fluid velocity at a solid boundary. Plausible reasons are advanced for ...

Brenner, Howard

123

Slip casting alumina with Na-CMC  

SciTech Connect

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

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

1996-11-01

124

Temporal Changes in Velocity and Recurrence due to Slip and Triggered Slip  

NASA Astrophysics Data System (ADS)

: Temporal elastic change within and adjacent to a fault zone can be (are always?) induced by slip. The temporal change is manifest as a velocity change followed by a long recovery process to the original equilibrium, or a new equilibrium, velocity. These changes are observed for both stick-slip and slow-slip, as well as triggered stick-slip and slow-slip. Based on laboratory and field observations, there is also a change in earthquake recurrence at slip and triggered slip time, that recovers together with the velocity to the original, or a new, equilibrium. The change in recurrence is the well known empirical Omori's law; however, we understand this behavior in the context of frictional physics. Laboratory studies suggest that both static stress change and/or nonlinear dynamical shaking of the volume in and around the slip event are responsible for the observed effects. The recovery process is due to material creep and/or slow dynamics, depending on the nature of the forcing [creep is induced from static stress change and slow dynamics is induced by dynamic shaking] (Guyer and Johnson, 2009). The change in velocity and/or recurrence may be proxies for a slip event. [We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work]. Nonlinear Mesoscopic Elasticity: The Complex Behaviour of Rocks and Soil, R. A. Guyer and P.A. Johnson, Wiley-VCH Verlag GmbH Berlin, 410 p. August 2009.

Johnson, P. A.

2011-12-01

125

Slipped capital femoral epiphysis: diagnosis and management.  

PubMed

Slipped capital femoral epiphysis is the most common hip disorder in adolescents, and it has a prevalence of 10.8 cases per 100,000 children. It usually occurs in children eight to 15 years of age, and it is one of the most commonly missed diagnoses in children. Slipped capital femoral epiphysis is classified as stable or unstable based on the stability of the physis. The condition is associated with obesity and growth surges, and it is occasionally associated with endocrine disorders such as hypothyroidism, growth hormone supplementation, hypogonadism, and panhypopituitarism. Patients usually present with limping and poorly localized pain in the hip, groin, thigh, or knee. Diagnosis is confirmed by bilateral hip radiography, which needs to include anteroposterior and frog-leg lateral views in patients with stable slipped capital femoral epiphysis, and anteroposterior and cross-table lateral views in patients with the unstable form. The goals of treatment are to prevent slip progression and avoid complications such as avascular necrosis and chondrolysis. Stable slipped capital femoral epiphysis is usually treated using in situ screw fixation. Treatment of unstable slipped capital femoral epiphysis usually involves in situ fixation, but there is controversy about the timing of surgery, value of reduction, and whether traction should be used. PMID:20672790

Peck, David

2010-08-01

126

Fatigue strength of socket welded pipe joint  

SciTech Connect

Fully reversed four point bending fatigue tests were carried out on small diameter socket welded joints made of carbon steels. Experimental parameters were pipe diameter, thicknesses of pipe and socket wall, throat depth and shape of fillet welds, slip-on and diametral gaps in the socket welding, lack of penetration at the root of fillet welds, and peening of fillet welds. In most cases a fatigue crack started from the root of the fillet, but in the case of higher stress amplitude, it tended to start from the toe of fillet. The standard socket welded joint for a pipe with a 50 mm nominal diameter showed a relatively low fatigue strength of 46 MPa in stress amplitude at the 10{sup 7} cycles failure life. This value corresponds to about 1/5 of that for the smoothed base metal specimens in axial fatigue. The fatigue strength decreased with increasing pipe diameter, and increased with increasing thickness of the pipe and socket wall. The effects of throat depth and shape of fillet welds on fatigue strength were not significant. Contrary to expectation, the fatigue strength of a socket welded joint without slip-on gap is Higher than that of the joint with a normal gap. A lack of penetration at the root deleteriously reduced fatigue strength, showing 14 MPa in stress amplitude at the 10{sup 7} cycles failure life for the 50 mm diameter socket joint.

Higuchi, Makoto [Ishikawajima-Harima Heavy Industries, Yokohama (Japan). Research Inst.; Hayashi, Makoto [Hitachi Ltd. (Japan). Mechanical Research Inst.; Yamauchi, Takayoshi [Mitsubishi Heavy Industries Ltd., Takasago (Japan). Takasago Research Inst.; Iida, Kunihiro [Shibaura Inst. of Technology, Tokyo (Japan). Dept. of Mechanical Engineering; Sato, Masanobu [Japan Power Engineering and Inspection Corp., Tokyo (Japan). Welding Engineering Dept.

1995-12-01

127

Discrete Element Modeling of Stick-Slip Instability and Induced Microseismicity  

NASA Astrophysics Data System (ADS)

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.

Khazaei, Cyrus; Hazzard, Jim; Chalaturnyk, Rick

2015-02-01

128

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

129

Nonlinear dynamical triggering of slow slip  

SciTech Connect

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.

Johnson, Paul A [Los Alamos National Laboratory; Knuth, Matthew W [WISCONSIN; Kaproth, Bryan M [PENN STATE; Carpenter, Brett [PENN STATE; Guyer, Robert A [Los Alamos National Laboratory; Le Bas, Pierre - Yves [Los Alamos National Laboratory; Daub, Eric G [Los Alamos National Laboratory; Marone, Chris [PENN STATE

2010-12-10

130

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

NASA Astrophysics Data System (ADS)

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

Chen, T.; Luo, H.

2013-12-01

131

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

132

Compliant joint  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

133

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

DOEpatents

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

Klein, Frederick F. (Monroeville, PA)

1989-01-01

134

Progressive slip after removal of screw fixation in slipped capital femoral epiphysis: two case reports  

PubMed Central

Introduction In slipped capital femoral epiphysis the femoral neck displaces relative to the head due to weakening of the epiphysis. Early recognition and adequate surgical fixation is essential for a good functional outcome. The fixation should be secured until the closure of the epiphysis to prevent further slippage. A slipped capital femoral epiphysis should not be confused with a femoral neck fracture. Case presentation Case 1 concerns a 15-year-old boy with an adequate initial screw fixation of his slipped capital femoral epiphysis. Unfortunately, it was thought that the epiphysis had healed and the screw was removed after 11 weeks. This caused new instability with a progressive slip of the femoral epiphysis and subsequently re-fixation and a subtrochanteric correction osteotomy was obligatory. Case 2 concerns a 13-year-old girl with persistent hip pain after screw fixation for slipped capital femoral epiphysis. The screw was removed as lysis was seen around the screw on the hip X-ray. This operation created a new unstable situation and the slip progressed resulting in poor hip function. A correction osteotomy with re-screw fixation was performed with a good functional result. Conclusion A slipped epiphysis of the hip is not considered ‘healed’ after a few months. Given the risk of progression of the slip the fixation material cannot be removed before closure of the growth plate. PMID:23181447

2012-01-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2015-06-01

136

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

EPA Science Inventory

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

137

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...

138

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...

139

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...

140

Slip casting of partially stabilized zirconia  

SciTech Connect

The toughness of partially-stabilized zirconia has been studied for some time. The tetragonal phase in partially stabilized ZrO2 transforms to the monoclinic phase under the influence of stress. Partially-stabilized ZrO2 has enhanced tensile strength, good wear resistance and low friction coefficient, and has found industrial applications. This article describes the use of partially-stabilized zirconia in slip casting. Lab techniques of slip casting have been reported for nonplastic materials such as Al2O3, CaF2, CaO-stabilized ZrO2 and MgO. The article discusses the variation of slip density and firing temperature and also reports the preparation of specimens of CaOstabilized ZrO2 by slip casting from ethanol-based suspensions. The preparation of Y2O3-ZrO2 compositions by slip casting from aqueous suspension is also reported. A Y2O3 partially stabilized ZrO2 powder was used as a starting material. The densities of the cast specimens were measured from the volume and weight, and those of the sintered specimens were measured by a liquid displacement technique using distilled water. The concentation of the suspension strongly affects the relative density of the cast specimen and the firing shrinkage of the sintered specimen, while the relative density of the sintered specimen is independent of the concentration of the suspension.

Taguchi, H.; Miyamoto, H.; Takahashi, Y.

1985-02-01

141

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

USGS Publications Warehouse

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.

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

2011-01-01

142

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

USGS Publications Warehouse

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.

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

143

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

PubMed

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

Du, Shuang; Gao, Yang

2012-01-01

144

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

PubMed Central

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

Du, Shuang; Gao, Yang

2012-01-01

145

Quake clamps down on slow slip  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

146

Evolution of slip surface roughness through shear  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

147

Hydrogen-affected cross-slip process in fcc nickel  

NASA Astrophysics Data System (ADS)

The effects of H on the cross-slip process of a dissociated screw dislocation in nickel are studied by atomistic simulations using a configuration-space-path technique. We find that H binding in the stacking fault exerts no effect on the activation energy of cross-slip. H that is bound to the cores of the partial dislocations and moves with the dislocations during cross-slip leads to an increase of the activation energy and thus induces slip planarity. Slip planarity is due only to a net decrease of the H-binding energy in the cross-slip process.

Wen, M.; Fukuyama, S.; Yokogawa, K.

2004-05-01

148

The mechanics of stick-slip  

USGS Publications Warehouse

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

Byerlee, J.D.

1970-01-01

149

Slipping processes in residual badlands reliefs  

NASA Astrophysics Data System (ADS)

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

Díaz-Hernández, Jose Luis; Yepes, Jorge

2010-05-01

150

Momentum compaction and phase slip factor  

SciTech Connect

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

Ng, K.Y.; /Fermilab

2010-10-01

151

Slipping magnetic reconnection in coronal loops.  

PubMed

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

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

2007-12-01

152

Joint chondrolysis.  

PubMed

Although the disease was first described in the hip, reports of chondrolysis in nearly all diarthrodial joints have since emerged with considerable variations in the literature.Despite speculation among clinicians and researchers about the implicit causal pathways and etiologic contributors associated with chondrolysis, definitive answers remain elusive.The term chondrolysis has been applied to varied levels of joint cartilage destruction from focal chondral defects to diffuse cartilage loss, revealing a lack of consistency in the application of diagnostic criteria to guide differential disease classification.Differentiating between the various potential etiologies associated with chondrolysis provides opportunities for the prevention of the disease. PMID:22048100

Provencher, Matthew T; Navaie, Maryam; Solomon, Daniel J; Smith, Jessica C; Romeo, Anthony A; Cole, Brian J

2011-11-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

154

Hip joint replacement  

MedlinePLUS

... made joint. The artificial joint is called a prosthesis . ... thromboembolic disease in patients undergoing elective hip and ... joint arthroplasties: current concepts of patient outcomes after ...

155

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

NASA Astrophysics Data System (ADS)

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.

Lindsey, E. O.; Fialko, Y.

2010-12-01

156

Slip casting and nitridation of silicon powder  

NASA Technical Reports Server (NTRS)

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

Seiko, Y.

1985-01-01

157

Slip-interface interaction at elevated temperatures  

Microsoft Academic Search

A dislocation model for the slip-interface interaction during high temperature deformation is developed based on a linear elasto-diffusion approach. The strength of the stress concentration at the interface depends on both geometrical and kinetic variables. A dislocation pile-up caused by microstructural instability may offer the most favorable site for cavity nucleation.

M. H. Yoo

1985-01-01

158

Ground Displacement by Strike-Slip Motion  

NSDL National Science Digital Library

This photograph illustrates strike-slip motion along a fault trace. The section of fence in the foreground has been offset 8.5 feet to the left relative to the segment in the background. The displacement occured in a rural area near Woodville, California, as a result of the San Francisco Earthquake on April 18, 1906.

159

Slip dynamics at a patterned rubber/glass interface during stick-slip motions.  

PubMed

We report on an experimental study of heterogeneous slip instabilities generated during stick-slip motions at a contact interface between a smooth rubber substrate and a patterned glass lens. Using a sol-gel process, the glass lens is patterned with a lattice of parallel ridges (wavelength, 1.6 ?m, amplitude 0.35 ?m). Friction experiments using this patterned surface result in the systematic occurrence of stick-slip motions over three orders of magnitude in the imposed driving velocity while stable friction is achieved with a smooth surface. Using a contact imaging method, real-time displacement fields are measured at the surface of the rubber substrate. Stick-slip motions are found to involve the localized propagation of transverse interface shear cracks whose velocity is observed to be remarkably independent on the driving velocity. PMID:22972225

Audry, M C; Fretigny, C; Chateauminois, A; Teissere, J; Barthel, E

2012-09-01

160

Estimating Friction Using Incipient Slip Sensing During a Manipulation Task  

E-print Network

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

Stanford University

161

Pivoting and slip in an angular contact bearing  

NASA Technical Reports Server (NTRS)

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

Kingsbury, E.

1983-01-01

162

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

E-print Network

We estimate the current slip rates on active conjugate strike-slip faults in central Tibet using repeat-pass synthetic aperture radar interferometry (InSAR). The conjugate fault systems are centered along the east trending ...

Taylor, Michael Halford; Peltzer, Gilles

2006-12-09

163

Joint assembly  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

164

Seismic Moment and Slip Distribution of the 1960 and 2010 Chilean Earthquakes as Inferred from Tsunami Waveforms  

NASA Astrophysics Data System (ADS)

The 27 February 2010 Chilean earthquake generated tsunami and caused significant damage on the Chilean coast. The tsunami was recorded at many tide gauge stations around the Pacific Ocean, as well as bottom ocean bottom pressure gauges of DART system. We inverted tsunami waveform data, recorded at 11 tide gauges in Chile and Peru and 4 nearby DART stations, to estimate the slip distribution on the fault. When we assume 36 subfaults (12 along strike by 3 downdip, size of each subfault is 50 km × 50 km), very large slip is located at the most downdip subfaults beneath coast and land. Tsunami waveforms recorded other DART stations also require such deep slips. However, other geodetic and seismic data do not show such deep slips, and tsunami data have limited resolution for such a deep onshore slip. We therefore used coastal uplift and subsidence data at 36 locations reported by Farias et al. (2010). The joint inversion indicates two asperities, one to the north around Constitucion and the other to the south around Arauco peninsula. While the largest slip is still located beneath the coast, the offshore slips generally become larger than the tsunami inversion. The total seismic moment is about 1.8 × 1022 Nm (Mw 8.8), similar to the value estimated from tsunami waveforms only, and the fault length is 450 km. For the 22 May 1960 Chilean earthquake, we first made an inversion of tsunami data, recorded at 12 tide gauge stations mostly in South America. When we assume 27 subfaults (9 along strike by 3 downdip, size of each subfault is 100 km × 50 km), the total seismic moment is 4.6 × 1022 Nm (Mw 9.0). Again, the largest slip is estimated at the deepest subfault beneath land near the epicenter, which would produce large coastal uplift where the coastal subsidence was reported by Plafker and Savage (1970). Poor station coverage of tide gauges may limit the resolution of slip distribution particularly at the southern part of the source area. We therefore made a joint inversion of tsunami and geodetic data, including coastal uplift and subsidence measured at 155 points and leveling data along the highway of 580 km. The total seismic moment is estimated as 8.1 × 1022 Nm (Mw 9.2), with the fault length of 800 km. Large slips of about 35 m are estimated at about 200 km south of the epicenter, which are consistent with the slip distributions modeled from geodetic data only (Barrientos and Ward, 1990; Moreno et al., 2009). The large slips are estimated at the southern end of the source region near Isla Guamblin and Isla Guafo, where large uplift is reported. The seismic moment from the joint inversion is similar to that estimated from geodetic data, and smaller than the results from seismic data analysis.

Satake, K.; Fujii, Y.

2010-12-01

165

Downscaling of slip distribution for strong earthquakes  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

166

The Long Term Slip Deficit Budget and the Seismic Cycle.  

NASA Astrophysics Data System (ADS)

Estimates of spatially heterogeneous coupling between plates in subduction zones provide a basis for forecasting high slip in future events; strong coupling between earthquakes, producing rapid strain accumulation, should be correlated with high slip during the next earthquake. However, studies comparing coupling and slip do not show the expected correlation . We test the hypothesis that slip is governed, not only by coupling, but by the long term history of loading and slip on the fault; strongly coupled locations which have experienced large slip in recent earthquakes may have low slip-deficit, a measure of accumulated strain energy on the fault, despite their relatively high slip-deficit rate. Using reconstructions of slip in historical and recent earthquakes under the Mentawai Islands, W. Sumatra, we show that coupling is strongly correlated with slip accumulated over several events on the same segment rather than on any single earthquake. This observation is inconsistent with the idea of a characteristic earthquake and even of an earthquake cycle which together form the basis of of deterministic earthquake forecasting . Instead it suggests that slip-deficit is accumulated according to the plate convergence rate moderated by the strength of coupling and is relaxed heterogeneously during slip events which need show no repeatability either in time or in space; the slip deficit budget, at least for the Mentawai megathrust segment, needs balanced only over hundreds of years. This implies that slip-deficit estimated by reconstruction of slip and loading over long times, is necessary to understand the current state of stress on active faults.

McCloskey, John; Simao, Nuno; Lindsay, Tony; NicBhloscaidh, Mairead; Murphy, Shane; Natawidjaja, Danny; Nalbant, Suleyman

2013-04-01

167

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

168

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

USGS Publications Warehouse

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.

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

1998-01-01

169

Mw 8.6 Strike-Slip Earthquake off Sumatra and Slip Partitioning  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

170

Equilibrium Statistics of Weakly Slip-Linked Gaussian Polymer Chains  

E-print Network

We calculate the free energy and the pressure of a weakly slip-linked Gaussian polymer chains. We show that the equilibrium statistics of a slip-linked system is different from one of the corresponding ideal chain system without any constraints by slip-links. It is shown that the pressure of a slip-linked system decreases compared with the ideal system, which implies that slip-linked chains spontaneously form aggregated cluster like compact structures. These are qualitatively consistent with previous theoretical analyses or multi chain simulations. We also show that repulsive potentials between chains, which have been phenomenologically utilized in simulations, can cancel the artificial pressure decrease.

Takashi Uneyama; Kazushi Horio

2011-04-15

171

Dynamical role of slip heterogeneities in confined flows.  

PubMed

We demonstrate that flows in confined systems are controlled by slip heterogeneities below a certain size. To show this we image the motion of soft glassy suspensions in microchannels whose inner walls impose different slip velocities. As the channel height decreases, the flow ceases to have the symmetric shape expected for yield-stress fluids. A theoretical model accounts for the role of slip heterogeneities and captures the velocity profiles. We generalize these results by introducing a length scale, valid for all fluids, below which slip heterogeneities dominate the flow in confined systems. General implications of this notion, concerning the interplay between slip and confinement, are presented. PMID:25353802

Vayssade, Anne-Laure; Lee, Choongyeop; Terriac, Emmanuel; Monti, Fabrice; Cloitre, Michel; Tabeling, Patrick

2014-05-01

172

On the mechanism of cross slip in Ni3AI  

NASA Astrophysics Data System (ADS)

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

Milligan, Walter W.; Antolovich, Stephen D.

1989-12-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

174

Generic element formulation for modelling bolted lap joints  

NASA Astrophysics Data System (ADS)

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

Ahmadian, Hamid; Jalali, Hassan

2007-07-01

175

Phase Slips in Oscillatory Hair Bundles  

PubMed Central

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

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

2013-01-01

176

Phase Slips in Oscillatory Hair Bundles  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

177

Smectite-illite transition during coseismic slip  

NASA Astrophysics Data System (ADS)

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

Takahashi, M.; Kitajima, H.

2013-12-01

178

Modeling of rock friction 2. Simulation of preseismic slip  

USGS Publications Warehouse

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.

Dieterich, J.H.

1979-01-01

179

Detailed history of slip along the Sunda mega-thrust  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

180

Slip complexity in earthquake fault models.  

PubMed Central

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

Rice, J R; Ben-Zion, Y

1996-01-01

181

Slip flow in non-circular microchannels  

Microsoft Academic Search

Microscale fluid dynamics has received intensive interest due to the emergence of Micro-Electro-Mechanical Systems (MEMS)\\u000a technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption\\u000a is no longer valid and a velocity slip may occur at the duct walls. Non-circular cross sections are common channel shapes\\u000a that can be produced by

Zhipeng Duan; Y. S. Muzychka

2007-01-01

182

Earthquake slip on oceanic transform faults.  

PubMed

Oceanic transform faults are one of the main types of plate boundary, but the manner in which they slip remains poorly understood. Early studies suggested that relatively slow earthquake rupture might be common; moreover, it has been reported that very slow slip precedes some oceanic transform earthquakes, including the 1994 Romanche earthquake. The presence of such detectable precursors would have obvious implications for earthquake prediction. Here we model broadband seismograms of body waves to obtain well-resolved depths and rupture mechanisms for 14 earthquakes on the Romanche and Chain transform faults in the equatorial Atlantic Ocean. We found that earthquakes on the longer Romanche transform are systematically deeper than those on the neighbouring Chain transform. These depths indicate that the maximum depth of brittle failure is at a temperature of approximately 600 degrees C in oceanic lithosphere. We find that the body waves from the Romanche 1994 earthquake can be well modelled with relatively deep slip on a single fault, and we use the mechanism and depth of this earthquake to recalculate its source spectrum. The previously reported slow precursor can be explained as an artefact of uncertainties in the assumed model parameters. PMID:11242043

Abercrombie, R E; Ekström, G

2001-03-01

183

Episodic Tremor and Slip: an Experimental Approach.  

NASA Astrophysics Data System (ADS)

We have devised a laboratory experiment to investigate the frictional and acoustic patterns of a salt slider over a large number of deformation cycles. We observe a continuous change of the frictional behavior of the slider under constant experimental conditions of stiffness, temperature and loading velocity. The stick-slip regime is progressively vanishing, eventually reaching the stable sliding regime. Concomitantly, the contact interface, observed under the microscope, develops a striated morphology with contact asperities increase in length and width, arguing for an increase in the critical slip distance dc. Complementary experiments including velocity jumps show that the frictional parameters of the rate and state friction law, a and b, progressively vanish with accumulated slip. The ultimate stage of friction is therefore rate and state independent under our experimental conditions. The Acoustic Emission evolves with cumulative displacement and interface ageing, following a trend from strong impulsive events to a collection of smaller amplitude and longer duration signals. We tentatively extend these results to natural subduction zones: shallow loud earthquakes, medium depth slow, deeper silent quakes and deepest steady-state creep are reproduced by the ageing of contact interface with cumulative displacement. In the meantime, the seismic energy release is evolving from seismic-like signals to NVT-like signals. NVT would emerge as the local recollection of the unstable behavior of the contact interface globally evolving towards the stable sliding regime.

Voisin, C.; Renard, F.; Larose, E.; Grasso, J.

2008-12-01

184

Slip length crossover on a graphene surface.  

PubMed

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

Liang, Zhi; Keblinski, Pawel

2015-04-01

185

Coseismic slip on shallow décollement megathrusts  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

186

Comparison of Joint Modeling Approaches Including Eulerian Sliding Interfaces  

SciTech Connect

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

Lomov, I; Antoun, T; Vorobiev, O

2009-12-16

187

Progressive slippage after pinning for slipped capital femoral epiphysis.  

PubMed

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

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

2002-01-01

188

Great Earthquakes With and Without Large Slip to the Trench  

NASA Astrophysics Data System (ADS)

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

Mori, J. J.

2013-12-01

189

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

NASA Astrophysics Data System (ADS)

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

McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

2014-05-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

191

Coseismic slip distribution of the 1923 Kanto earthquake, Japan  

USGS Publications Warehouse

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.

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

2005-01-01

192

Earthquake-Like Slip Events on a Laboratory Fault  

NASA Astrophysics Data System (ADS)

We generated dynamic slip events with prescribed total energy on an experimental fault. Sliding occurred between granite rings, in a rotary shear apparatus driven by a 100 hp motor and a massive flywheel (225 kg) at normal stress up to 7 MPa (Lockner and Reches, this meeting). In the experiments, the motor first brought the flywheel to a pre-selected angular velocity. Then, the motor was disengaged and the flywheel was connected to one granite block through a fast-acting clutch, initiating slip between the rotating and stationary blocks. The rate- and slip- dependent friction of the simulated fault surface controlled the slip velocity and slip distance until the kinetic energy of the flywheel was consumed. The flywheel kinetic energy density (per unit area of the sliding surfaces) ranges from 75 J/m2, which is insufficient to initiate slip, to 3.6 106 J/m2, which generates slip events with duration of ~2 s, maximum slip velocity 0.6-0.7 m/s, and slip distance 0.6-0.9 m. The main observations are: (1) Rise-time < 0.1s for all events; (2) Fault locked until the shear stress reaches yield stress (sliding friction of 0.65-0.8); (3) Modest drop (5-15%) of shear strength during sliding at slip velocities less than 0.25 m/s. (4) Significant weakening at slip velocity greater than 0.25 m/s, and this weakening is associated with the onset of ‘chattering slip’ (= continuous high-frequency stick-slip events); (5) power law relations between total sliding distance and flywheel energy. The research was supported by NSF grant # 0732715.

Chang, J. C.; Reches, Z.; Lockner, D. A.; Totten, M. W., Jr.

2009-12-01

193

Cartilage Space Width in Slipped Capital Femoral Epiphysis: The Relationship to Cartilage Necrosis 1  

PubMed Central

The radiolucent cartilage space of eighty-three patients with unilateral or bilateral slipped capital femoral epiphysis was measured by a standardized technique. In the majority of patients, whether unilateral or bilateral involvement, there was bilateral narrowing of the cartilage space. In the unaffected hip of unilaterally involved patients, there was a progressive narrowing as skeletal maturity was attained. A concomitant anatomical study of cadaver hips, removed at autopsy from adolescent patients, showed a progressive narrowing of the cartilage as the proximal femur matured. Black females showed most narrowing (minimum cartilage space width), had the narrowest final cartilage space widths, and took the longest to attain this final width. While other racial, sexual and therapeutic groups failed to demonstrate statistically significant differences, the general trend was for females, Blacks, and patients treated by osteotomy to have more joint space narrowing. However, rewidening occurred in most of these affected joint spaces, in contrast to the progressive linear decrease observed in unaffected hips and anatomical specimens. On the basis of this study, we feel that cartilage space narrowing may be anticipated in the post-operative period in most patients treated for slipped capital femoral epiphysis. This narrowing appears to improve with time. Narrowing of greater than one-half the original width, in association with pain and limitation of joint function, probably represents “cartilage necrosis,” or pathologic joint space narrowing. Unless the narrowing remains less than one-half to two-thirds of the initial cartilage space for more than twenty-four to thirty-six months, probably no specific surgical treatment should be undertaken, other than observation and protected weight bearing during any painful phase. Plotting the roentgenographic cartilage space width during the three month to thirty-six month phase may be useful in monitoring and predicting the outcome. ImagesFIG. 2FIG. 3 PMID:848047

Ogden, John A.; Simon, Theodore R.; Southwick, Wayne O.

1977-01-01

194

Fully developed laminar slip and no-slip flow in rough microtubes  

NASA Astrophysics Data System (ADS)

The effect of surface roughness on developed laminar flow in microtubes is investigated. The tube boundary is defined by {r=R[{1+\\varepsilon sin( {? ? })}]}, with R representing the reference radius and {\\varepsilon} and ? the roughness parameters. The momentum equation is solved using Fourier-Galerkin-Tau method with slip at the boundary. A novel semi-analytical method is developed to predict friction factor and pressure drop in corrugated rough microtubes for continuum flow and slip flow that are not restricted to small values of {\\varepsilon ? } . The analytical solution collapses onto the perturbation solution ofDuan and Muzychka (J. Fluids Eng., 130:031102, 2008) for small enough values of {\\varepsilon ? }.

Akyildiz, F. Talay; Siginer, Dennis A.

2011-08-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

196

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

USGS Publications Warehouse

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

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

2012-01-01

197

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

198

Molecular imaging of slip in entangled DNA solution.  

PubMed

This work obtains the first molecular imaging of wall slip in entangled solutions. Using a combination of confocal fluorescence microscopy and rheometry, molecular images were captured in the nonlinear response regime of entangled DNA solutions. Conformations of DNA molecules were imaged during shear to correlate with the magnitude of wall slip. Interfacial chain disentanglement results in wall slip beyond the stress overshoot. Sufficient disentanglement can produce tumbling of individual DNA in the entangled solutions. PMID:20867741

Boukany, Pouyan E; Hemminger, Orin; Wang, Shi-Qing; Lee, L J

2010-07-01

199

Slip casting of silicon nitride for pressureless sintering  

Microsoft Academic Search

Properties of aqueous slips of silicon nitride\\/spinel mixtures were studied. Vanisperse CB was used as deflocculant. It was shown that mixtures previously milled in water form stable slips, while those milled in isopropanol form jelly-like aqueous suspensions unsuitable for casting. A single-stage slip may be prepared by milling and mixing Si3 N4 powder with spinel and water without a deflocculant.

E. M. Rabinovich; Sh. Leitner; A. Golden Berg

1982-01-01

200

The no-slip boundary condition in fluid mechanics  

Microsoft Academic Search

Ideas leading to the resolution of the problem of no-slip condition for fluid velocity at a solid surface are traced in this\\u000a concluding part of the article. In the continuum limit velocity slip being zero is established beyond any doubt now. Even\\u000a turbulent flows which have a large velocity gradient near a wall have to satisfy the no-slip condition at

Sandeep Prabhakara; M. D. Deshpande

2004-01-01

201

DEM simulation of growth normal fault slip  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

202

Large area multiturn superfluid phase slip gyroscope  

NASA Astrophysics Data System (ADS)

We have built and tested a large area multiturn superfluid 4He phase slip gyroscope. This device demonstrates quantum-mechanical phase coherence of superfluid 4He over a macroscopic length scale (1.4 m). The sensing loop area of this device is two orders of magnitude larger than our proof-of-principle model, with an improvement in sensitivity of ˜20 over any other superfluid 4He gyroscope. We find that this rotation sensor has excellent long-term stability. In addition, there are no new noise sources preventing further enhancements in sensitivity.

Bruckner, Niels; Packard, Richard

2003-02-01

203

Slip stacking experiments at Fermilab main injector  

SciTech Connect

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

Kiyomi Koba et al.

2003-06-02

204

Microfluidics: The no-slip boundary condition  

E-print Network

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

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

2005-09-28

205

Slipped capital femoral epiphysis: what's new?  

PubMed

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

Peck, Kathryn; Herrera-Soto, José

2014-01-01

206

Joint Instability and Osteoarthritis  

PubMed Central

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

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

2015-01-01

207

Inverting measurements of surface slip on the Superstition Hills fault  

USGS Publications Warehouse

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

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

1989-01-01

208

Manifestations of Strike-Slip Faulting on Ganymede  

NASA Technical Reports Server (NTRS)

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

DeRemer, Lindsay C.; Pappalardo, Robert T.

2003-01-01

209

Strong dynamical effects during stick-slip adhesive peeling  

E-print Network

We consider the classical problem of the stick-slip dynamics observed when peeling a roller 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.

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

2013-11-14

210

Slip flow of diverse liquids on robust superomniphobic surfaces.  

PubMed

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

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

2014-01-15

211

Slip, Trip and Fall Prevention for Healthcare Workers  

MedlinePLUS

... Number 2011–123 December 2010 Safer • Healthier • People TM v Contents Part I. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Slip, Trip, ... NIOSH) Publication No. 2011–123 safer • healthier • people tm

212

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

PubMed

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

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

2015-02-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

214

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

PubMed Central

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

Parijat, Prakriti; Lockhart, Thurmon E.

2015-01-01

215

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

216

Slip distributions of three slow slip events beneath the Bungo Channel, southwest Japan, inferred from new inversion analyses of GPS data  

NASA Astrophysics Data System (ADS)

We estimated spatio-temporal slip distributions of three long-term slow slip events, which occurred on a plate interface beneath the Bungo Channe located at convergent plate boundary between the oceanic Philippine Sea plate and the continental Amurian plate, southwest Japan during periods from 1997 to 1998, 2002 to 2004, and 2009 to 2011. For this purpose, we developed a new inversion method using ABIC which includes three prior constraints: slip distribution is smooth to some extent, slip directions are mostly oriented in the direction of plate convergence, and a temporal change of slip is smooth to some extent. As a result, the three long-term slow slip events had a common feature that slipped region spread southwestward with acceleration of slip rates. We also found that major slipped regions moved southwestward with approximately 50 km/yr. On the other hand, southwestward or northeastward motion of slipped regions were able to be identified before or after the periods when slip rates were fast, whose direction was different from event by event. Comparing the obtained spatio-temporal slip distributions of the three slow slip events with slip-deficit rate distributions obtained in our previous study, we also investigated process of strain accumulation and release caused by the latter and the former, respectively. In the western plate interface beneath the Bungo Channel, since slip-deficit rate was small and the amounts of slips associated with the three slow slip events were large, most of the accumulated slip-deficit was estimated to be released. On the other hand, in the eastern plate interface, slip-deficit rate was large and the amounts of slips associated with the three slow slip events were small, slip-deficit was estimated to be accumulated effectively.

Yoshioka, S.; Matsuoka, Y.

2013-12-01

217

Anisotropic Permeability of a Strike Slip Fault  

NASA Astrophysics Data System (ADS)

Pump tests were performed in isolated sections of two inclined ~200m long boreholes that are ~130 meters apart from each other (WF-4 and WF-5 in Figure 1). The boreholes penetrate the Wildcat Fault, a semi-vertical strike slip fault, which is a member of the Hayward Fault system situated in the Berkeley Hills. The geology encountered in the boreholes was predominantly the Claremont Fm., extensively fractured and alternating sequences of chert, shale and sandstone. The drawdowns in four isolated sections in a vertical borehole (WF-1) drilled adjacent to the fault at distances of ~45m and ~95m from each of the inclined borehole was analyzed. The permeability of the fault plane was found to be two orders of magnitude higher than that of the protolith and anisotropic with approximately 10 fold higher permeability in near horizontal direction, which is somewhat expected for a strike slip fault (Figure 2). Build-up analysis suggests that the fault is asymmetric with higher permeability along the east side of the fault plane and lower along the west side.igure 1. Pumping test configuration with two inclined boreholes (WF-4 and WF-5) intersecting the Wildcat Fault. The vertical borehole WF-1 is situated very close to the fault. igure 2. Dimensionless directional drawdowns observed in four isolated sections in WF-1 in response to the pumping in WF-4 and WF-5 at a dimensionless time of 16. Also shown is the best fit permeability ellipse.

Karasaki, K.; Goto, J.; Kiho, K.

2012-12-01

218

Frictional slip of granite at hydrothermal conditions  

USGS Publications Warehouse

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

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

1995-01-01

219

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

USGS Publications Warehouse

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

Rymer, M.J.; Tinsley, 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

220

Strike-slip earthquakes on moderately-dipping faults  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

221

Seismic and aseismic slip on the central Peru megathrust.  

PubMed

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

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

2010-05-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

223

Slow slip, tremor, and local earthquakes prior to the Mw 7.4 megathrust event in Oaxaca  

NASA Astrophysics Data System (ADS)

The search for observations to demonstrate slow slip phenomena can trigger large and damaging earthquakes is fueled by theoretical predictions that slip in the deeper transitional zone can promote failure in the shallow seismogenic zone. If such a link is verified, then operational earthquake forecasting could be improved by incorporating more slow slip behaviors. The subduction zone in Oaxaca, Mexico provides an ideal locality to investigate this potential relationship, where a joint seismic-geodetic network provides a multi-year record of traditional earthquakes, tectonic tremor, and slow slip events (SSE) prior to the recent March 12, 2012 Mw 7.4 megathrust Ometepec earthquake. Geodetically detected SSEs are observed for 2-3 months every 1-2 years, where stronger signals originate in the updip portion of the transition zone. In the months preceding the Ometepec mainshock, visual inspection of GPS time series for the 2011-2012 SSE suggests a migration of slip from east to west, along strike toward the source region of the earthquake. Preliminary models of the time series confirm slip ends just downdip of the epicenter in the weeks prior to the earthquake. While slow slip activity is prominent in the months leading up to the mainshock, tremor activity remains near background levels for much of that time, particularly in the days leading up to the earthquake. Observations from single station frequency scanning, beginning in mid-2006 show tremor activity is located further down-dip than SSE and occur over relatively short time periods, 2-10 days and recurs as often as every 2-3 months. Curiously, if we look at the preceding year, more tremor activity is detected during the nearly 6-month 2011 slow slip event. To further investigate the relationship between SSEs, tremor, and megathrust earthquakes, we use a multi-station template waveform matching technique to detect and locate events several of orders of magnitude smaller than would be possible using traditional techniques. Visible aftershocks are used as templates to identify and characterize multi-year pre-event seismicity of specific "template families" near or within the eventual rupture zone. Preliminary analysis suggests that families of earthquakes in between the SSE and the Mw 7.4 epicenter are active in the weeks prior to the mainshock. Examination of several years of seismicity prior to the megathrust event shows that some families are more active during SSEs. Despite an unclear correlation between tremor and the megathrust event, preliminary results indicate a slow slip event and template earthquake families are active prior to the Ometepec earthquake. While detailed geodetic modeling is underway to better define the source zones of slow slip over time, our hypothesis is that periods of slow slip at the shallower end of the transition zone increase the potential for a megathrust event, whereas periods of slow slip focused towards the deeper end of the transition zone increase tremor activity.

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

2013-05-01

224

Slip flow through colloidal crystals of varying particle diameter.  

PubMed

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

Rogers, Benjamin J; Wirth, Mary J

2013-01-22

225

Discussion of slip boundary on fibrous filter media  

Microsoft Academic Search

In modeling fibrous filter media, it is important to consider the phenomena of slip on the fiber surface because of the Knudsen number limit. In this paper the available analytical expressions for slip boundary were summarized and applied on a novel fibrous filter media model. Experimental data of the pressure drop on the filter media was used to validate the

Bin Zhou; Xiaosong Zhang; Paolo Tronville

2010-01-01

226

Large area multiturn superfluid phase slip gyroscope Niels Brucknera)  

E-print Network

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

Packard, Richard E.

227

Proprioception and joint stability  

Microsoft Academic Search

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

J. Jerosch; M. Prymka

1996-01-01

228

Joint Infection (Beyond the Basics)  

MedlinePLUS

... Infection of an artificial joint is known as prosthetic joint infection. GONOCOCCAL JOINT INFECTION Gonococcal joint infection ... cases, it is not possible to replace the prosthetic joint, and surgery to fuse the bones is ...

229

Superplastic nanofibrous slip zones control seismogenic fault friction  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

230

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

231

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

232

Learning and Prediction of Slip from Visual Information  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

233

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

PubMed

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

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

2014-12-12

234

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

235

Thermal slip for liquids at rough solid surfaces  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

236

Local tsunamis and distributed slip at the source  

USGS Publications Warehouse

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.

Geist, E.L.; Dmowska, R.

1999-01-01

237

Double-taper slip-on drill string stabilizer  

SciTech Connect

A stabilizer is described for use on a drill collar which comprises: (a) a cylindrical body with: (i) a longitudinal bore, (ii) internally threaded end portions, (iii) a double-tapered inner surface extending between the end portion and a relatively thicker central portion; (b) a hollow end cap at each end of the body threaded externally to mate with the corresponding internally threaded portion of the body and having a circumferential groove in the internal surface thereof near the outboard end thereof; (c) double-tapered slip segments within each end of the body adapted to mate and wedge against the double-tapered inner surface at the end of the body upon entry of one of the end caps into the end of the body; the slip segments being distributed around the body, the slip segment having: (i) a longitudinal slot, and (ii) a circumferential recess in the exterior surface thereof near the outboard end of the slip segment facing the end cap, the circumferential recess defining a retaining lip on the external surface of the slip segment which fits within the circumferential groove in the end cap; (d) an expansible member configured to engage the inner surfaces of the slip segments as to urge the lips of the slip segments radially into the circumferential recess of the end cap; (e) a compressible renitent member positioned within the slip segment recess between the threaded terminus of the end cap and the slip segment so as to be compressed upon entry of the end cap into the body; and (f) a locking device interengaging the slip segment longitudinal slot and the body to resist rotational movement therebetween.

Beasley, T.R.

1986-07-15

238

Constraining fault constitutive behavior with slip and stress heterogeneity  

USGS Publications Warehouse

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

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

2008-01-01

239

Shallow slip deficit due to large strike-slip earthquakes in dynamic rupture simulations with elasto-plastic off-fault response  

Microsoft Academic Search

Slip inversions of geodetic data from several large (magnitude ˜7) strike-slip earthquakes point to coseismic slip deficit at shallow depths (<3-4 km), that is, coseismic slip appears to decrease towards the Earth surface. While the inferred slip distribution may be consistent with laboratory-derived rate and state friction laws suggesting that the uppermost brittle crust may be velocity strengthening, there remains

Y. Kaneko; Y. Fialko

2011-01-01

240

Slipped capital femoral epiphysis in children.  

PubMed

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

Loder, R T

1995-02-01

241

Floor/shoe slip resistance measurement.  

PubMed

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

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

1992-05-01

242

Numerical Investigations of the Dynamic Shear Behavior of Rough Rock Joints  

NASA Astrophysics Data System (ADS)

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

Huang, Junyu; Xu, Songlin; Hu, Shisheng

2014-09-01

243

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

SciTech Connect

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

Raabe, D.; Keichel, J.; Gottstein, G. [RWTH, Aachen (Germany). Inst. fuer Metallkunde und Metallphysik] [RWTH, Aachen (Germany). Inst. fuer Metallkunde und Metallphysik

1997-07-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

245

Shear experiments of granular materials and implications for fault slip  

NASA Astrophysics Data System (ADS)

Faults are known to slip irregularly in the form of stick-slip. There are various parameters which affect this motion (e.g., particle size, shear rate). But how each of these parameters affect the motion is unclear. Recently, Anthony and Marone (2005) performed laboratory experiments to investigate how the periodicity or slip are controlled by the particle properties of fault gouge. However, particle size was not varied much and the effect of interstitial fluid was unexplored. Fluid effects are considered to be important for understanding slip in subduction zones (Obara, 2002). Here we present the results of shear experiments of dry and liquid-saturated granular materials to understand how the properties of fault gouge and the imposed shear rate control the long-term statistics of fault slip. We shear sorted glass beads using a rotating viscometer and find that they exhibit stick-slip. We characterize the temporal variation of torque measurements using several scales, and analyze their statistical properties. Under a fixed rotation rate we find that as the particle size increases, the stress drop and the slip recurrence interval increases whereas the degree of creeping prior to the slip decreases. From analyzing the images of the upper surface of sheared granular materials, we find that the radial range where particles are mobile are approximately scaled as 10-15 particle size, and hence the number of particles consisting a force chain is approximately constant. Using these results, we calculate the minimum shear strain needed for a slip to occur and find that for a particle size of 0.196 mm it is 5 × 10-3 for a shear rate of 1 × 10-2 1/s and tends to decrease with increasing particle size. Our results indicate that the difference in the stick-slip behavior primarily arise from the difference in interparticle friction which increases with particle size. When the granular material is saturated with viscous fluid, we find that the interparticle friction is drastically reduced thus affecting the stress drop and degree of preslip creep. Although our granular model of fault slip is much simplified, it demonstrates that for the same far-field slip rate the difference of the effective particle size of fault gauge or the presence of interstial liquid can account for the variation of fault behavior from creeping to stick-slip.

Higashi, N.; Sumita, I.

2007-12-01

246

Bulletin of the Seismological Society of America, Vol. 86, No. 1B, pp. $49-$70, February 1996 The Slip History of the 1994 Northridge, California, EarthquakeDetermined  

E-print Network

States since the great 1906 San Francisco earthquake (USGSand SCEC,1994). Peak acceleration and velocity The Slip History of the 1994 Northridge, California, EarthquakeDetermined from Strong-Motion, Teleseismic a rupture model of the Northridge earthquake, determined from the joint inversion of near-source strong

Greer, Julia R.

247

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

USGS Publications Warehouse

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.

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

2001-01-01

248

Butt Joint Tool Commissioning  

SciTech Connect

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

Martovetsky, N N

2007-12-06

249

Perception of slipperiness and prospective risk of slipping at work  

PubMed Central

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

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

2013-01-01

250

Microslips as precursors of large slip events in the stick-slip dynamics of sheared granular layers: A discrete element model analysis  

NASA Astrophysics Data System (ADS)

We investigate the stick-slip behavior of a granular system confined and sheared by deformable solid blocks using three-dimensional discrete element method simulations. Our modeling results show that large slip events are preceded by a sequence of small slip events—microslips—whose occurrence accelerates exponentially before the large slip event onset. Microslips exhibit energy release several orders of magnitude smaller than the large slip events. The microslip event rate is proposed as a measure of slip activity in the granular gouge layer. A statistical analysis shows that microslip event rate correlates well with large slip event onset and that variations in it can be used to predict large slip events. The emergence of microslips and their duration are found to be controlled by the value of the slipping contact ratio and are therefore related to the jamming/unjamming transition of frictional granular packings.

Ferdowsi, B.; Griffa, M.; Guyer, R. A.; Johnson, P. A.; Marone, C.; Carmeliet, J.

2013-08-01

251

Frictional Slip Resistance at Glacier Beds due to Rock Debris  

NASA Astrophysics Data System (ADS)

Slip at the bases of wet-based ice masses may share more in common with slip along crustal faults than previously suspected. The ice plain of Whillans ice stream moves by persistent slick-slip motion with associated basal seismicity (Wiens, et al., 2007, Nature) Additional evidence for stick-slip over shorter time and length scales comes from seismic studies elsewhere in Antarctica (Danesi et al., 2006, EPSL) and from Trapridge Glacier, where brief but large water pressure pulses in closed boreholes are interpreted to reflect stress transients associated with minute, episodic slip events (Kavanaugh, in press, JGR-ES). These observations indicate that slip resistance over some portions of glacier beds can be dominantly frictional, rather than viscous or viscoplastic as is commonly assumed for both hard and soft beds. Rock debris, either within basal ice or in a soft bed, is a source of such friction. Measurements at Engabreen, Norway, indicate that friction between debris in ice and a hard bed can locally be comparable to the bed shear stress, indicating that over some parts of the bed rock friction can exceed viscous drag on bedrock bumps. Laboratory studies of till deformation relevant to soft beds indicate that Coulomb models best approximate steady-state deformation but with subtle rate dependencies at small strains. Glacier slip across a till bed, triggered by high water pressure with associated shear relaxation of till, has been measured beneath several glaciers. Moreover, laboratory experiments indicate that resistance to this slip can decrease with increasing slip velocity, the converse of viscous rate strengthening. This velocity weakening is measured commonly in friction experiments with fault gouge and is a fundamental requirement for stick-slip motion and consequent seismicity. These subglacial and laboratory data, therefore, are broadly consistent with larger-scale observations of stick-slip and basal seismicity on some glaciers. The implication, in agreement with some models of glacier flow, is that sections of glacier beds with slip resistance dominated by debris friction may have little or no capacity for viscous rate strengthening. In such zones stable flow can be achieved only through interaction with adjacent ice.

Iverson, N. R.; Cohen, D.; Hooyer, T. S.; Thomason, J. F.; Moore, P. L.; Jackson, M.

2008-12-01

252

Atomistic Determination of Cross-Slip Pathway and Energetics  

NASA Astrophysics Data System (ADS)

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

Rasmussen, T.; Jacobsen, K. W.; Leffers, T.; Pedersen, O. B.; Srinivasan, S. G.; Jónsson, H.

1997-11-01

253

Cooperative atomic motions and core rearrangement in dislocation cross slip  

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

254

Nanoliter multiplex PCR arrays on a SlipChip  

PubMed Central

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

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

2010-01-01

255

Size Effects and Phase Slip in Charge Density Wave Systems.  

NASA Astrophysics Data System (ADS)

Experimental studies are presented concerning the nature of phase slip in charge-density wave (CDW) systems. The phase slip process is of fundamental importance in CDW systems, and has direct analogies to phase slip in superconductors and superfluids. It is also shown that geometry effects are important in determining the dynamics of the CDW. In order for the CDW to satisfy its boundary conditions, phase slip is required wherever the local drift velocity changes. A length-independent voltage V_ {ps} must be applied to the CDW, in addition to the length-dependent resistive voltage, in order to initiate longitudinal phase slip and allow current flow. A theory is outlined in which this V_{ps } causes a large static strain in the CDW. Phase slip proceeds via homogeneous, three-dimensional, thermally -activated nucleation of dislocation loops in the CDW, which then grow under the influence of the stress to drive current flow. Experimental measurements of phase slip in the CDW conductor NbSe_3 are presented. The phase slip rate is shown to be qualitatively and semi-quantitatively consistent with the 3D phase slip theory. Phase slip is insensitive to impurity concentration, and only weakly dependent upon variations in the electric field profile within the sample. These observations support the notion that phase slip does not rely upon localized nucleation centers, but rather occurs homogeneously within the sample. The impurity pinning force of the CDW in NbSe _3 has been shown to depend inversely upon the sample thickness, due to the enormous phase coherence length. Most samples of NbSe_3 have significant variations in thickness across their width. Under the application of an electric field, competition between the desired velocities of the various parts of the sample, mediated by phase slip, are shown to generate most of the 1/f-type noise. This competition also smears out the depinning transition. A number of effects, including scaling behavior at threshold, incomplete mode locking, and incoherent narrow -band noise long assumed to be intrinsic to the CDW response, are thus shown to be associated with velocity shear along thickness steps.

Maher, Michael Patrick

256

The Frictional Proprierties of Dolomite Gouges at Subseismic Slip Rates  

NASA Astrophysics Data System (ADS)

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

Faoro, I.; De Paola, N.

2011-12-01

257

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

258

Risk Management Institute Joint Seminar Joint Seminar -  

E-print Network

around their use of leverage. Research on optimal leverage in the money management industry, howeverRisk Management Institute Joint Seminar Joint Seminar - Risk Management Institute And Department A (S14, #03-10) Speaker Prof. Wang Hefei University of Illinois, Chicago Title Leverage Management

Chaudhuri, Sanjay

259

Peeling-angle dependence of the stick-slip instability during adhesive tape peeling.  

PubMed

The influence of peeling angle on the dynamics observed during the stick-slip peeling of an adhesive tape has been investigated. This study relies on a new experimental setup for peeling at a constant driving velocity while keeping constant the peeling angle and peeled tape length. The thresholds of the instability are shown to be associated with a subcritical bifurcation and bistability of the system. The velocity onset of the instability is moreover revealed to strongly depend on the peeling angle. This could be the consequence of peeling angle dependance of either the fracture energy of the adhesive-substrate joint or the effective stiffness at play between the peeling front and the point at which the peeling is enforced. The shape of the peeling front velocity fluctuations is finally shown to progressively change from typical stick-slip relaxation oscillations to nearly sinusoidal oscillations as the peeling angle is increased. We suggest that this transition might be controlled by inertial effects possibly associated with the propagation of the peeling force fluctuations through elongation waves in the peeled tape. PMID:25363615

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

2014-12-28

260

From frictional fingers to stick slip bubbles  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

261

Torsional stick-slip behavior in WS2 nanotubes.  

PubMed

We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (WS2). When an external torque is applied to a WS2 nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. We present a theoretical model based on density-functional-based tight-binding calculations, which explains the torsional stick-slip behavior in terms of a competition between the effects of the in-plane shear stiffness of the WS2 walls and the interwall friction arising from the atomic corrugation of the interaction between adjacent WS2 walls. PMID:19113281

Nagapriya, K S; Goldbart, Ohad; Kaplan-Ashiri, Ifat; Seifert, Gotthard; Tenne, Reshef; Joselevich, Ernesto

2008-11-01

262

Torsional Stick-Slip Behavior in WS2 Nanotubes  

NASA Astrophysics Data System (ADS)

We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (WS2). When an external torque is applied to a WS2 nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. We present a theoretical model based on density-functional-based tight-binding calculations, which explains the torsional stick-slip behavior in terms of a competition between the effects of the in-plane shear stiffness of the WS2 walls and the interwall friction arising from the atomic corrugation of the interaction between adjacent WS2 walls.

Nagapriya, K. S.; Goldbart, Ohad; Kaplan-Ashiri, Ifat; Seifert, Gotthard; Tenne, Reshef; Joselevich, Ernesto

2008-11-01

263

Brittle-viscous deformation, slow slip, and tremor  

NASA Astrophysics Data System (ADS)

Geophysical observations have illuminated a spectrum of fault slip styles from continuous aseismic sliding to fast earthquake slip. We study exhumed intercalated lenses of oceanic crust and sedimentary rocks, deformed to high shear strains. Deformation was partitioned between fractured, rigid blocks, with lengths of tens to hundreds of meters, and surrounding metapelites characterized by interconnected phyllosilicate networks. Under inferred conditions of low effective stress at temperatures > 500°C, locally and transiently elevated shear strain rate in phyllosilicates deforming by dislocation creep can reach those needed for transient slow slip. Concurrently, increased matrix strain rate likely stimulates brittle failure in rigid lenses. The ubiquitous presence of quartz veins and microfractures within rigid material provides evidence for brittle deformation occurring coincident with viscous shearing flow. We suggest that geophysically observed tremor and slow slip may be a manifestation of strain partitioning, where deformation is accommodated viscously in a matrix enveloping rigid lenses.

Fagereng, Åke; Hillary, Graeme W. B.; Diener, Johann F. A.

2014-06-01

264

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

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

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

265

Submicrometer particles and slip flow in liquid chromatography.  

PubMed

Smaller particles have progressively led to higher efficiency in liquid chromatography, particularly for proteins, due to smaller diffusion distances. Particle diameter has recently entered the submicrometer region, with the back-pressure requirements alleviated by slip flow. PMID:25646567

Rogers, Benjamin A; Wu, Zhen; Wei, Bingchuan; Zhang, Ximo; Cao, Xiang; Alabi, Oyeleye; Wirth, Mary J

2015-03-01

266

Independence of slip velocities on applied stress in small crystals.  

PubMed

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

Maaß, R; Derlet, P M; Greer, J R

2015-01-21

267

Frictional melting and stick-slip behavior in volcanic conduits  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

268

Slip ring experience in long duration space applications  

NASA Technical Reports Server (NTRS)

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

Phinney, Damon D.

1986-01-01

269

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

PubMed Central

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

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

2014-01-01

270

Slope traversal experiments with slip compensation control for lunar\\/planetary exploration rover  

Microsoft Academic Search

This paper presents slope traversal experiments with slip compensation control for lunar\\/planetary exploration rovers. On loose soil, wheels of the rover easily slip even when the rover travels with relatively low velocity. Because of the slip, following an arbitrary path on loose soil becomes a difficult task for the rover, and also, the slip will increase when the rover traverses

Genya Ishigami; Keiji Nagatani; Kazuya Yoshida

2008-01-01

271

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

E-print Network

148 Cycle slip Detection in the context of rtK GPs positioning of lightweight UAVs C. Eling1 , E for a reliable detection and repair of cycle slips. Keywords RTK GPS, UAV, direct georeferencing, cycle slip, this paper is focused on the cycle slip detection based on accelerometers in a Kalman filter. By means

Behnke, Sven

272

Spatial and temporal evolution of stress and slip rate during the 2000 Tokai slow earthquake  

E-print Network

to infer the state of plate locking at the Suruga-Nankai Trough in terms of slip deficit or ``backslip slip deficit rates as large as $3­4 cm/yr, with a maximum slip deficit rate off Cape Omaezaki 138.36°ESpatial and temporal evolution of stress and slip rate during the 2000 Tokai slow earthquake Shin

Segall, Paul

273

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

E-print Network

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

Schieber, Jay D.

274

Effects of slip testing parameters on measured coefficient of friction  

Microsoft Academic Search

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

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

2007-01-01

275

Use of concentrated solar energy to form slip coatings  

Microsoft Academic Search

Melted slip coatings were obtained and the structural changes in the coatings and their substrates upon simultaneous heating by concentrated solar radiant energy fluxes were studied. Well known wear and corrosion resistant TiC-Ni-B and WC-Ni-B coatings 50 to 300 microns thick applied by the slip method to flat or cylindrical stainless steel and titanium specimens were examined. The specimens were

A. A. Korol; Y. A. Korol; I. Y. Kasich-Pilipenko; P. A. Verkhovodov; V. S. Dvernyakov; V. K. Kadyrov

1983-01-01

276

Optical Slip Rings for Home Security High-Definition Cameras  

Microsoft Academic Search

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

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

2007-01-01

277

Dislocation Cross-Slip in Nanocrystalline fcc Metals  

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

278

Microscopic stick–slip in friction force microscopy  

Microsoft Academic Search

Friction force measurements were performed on 2-hydroxy stearic acid (2-HSA) and 12-hydroxy stearic acid (12-HSA) coated silica\\u000a surfaces in air using an atomic force microscope. The 2-HSA displayed viscoelastic behaviour with a yield point as the static–dynamic\\u000a friction transition. Steady sliding motion was replaced by microscopic stick–slip at lower velocities and higher loads. Stick–slip\\u000a motion was successfully described and fitted

Anders Meurk

2000-01-01

279

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

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

Shekhar, S.

1997-03-01

280

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

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

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

1996-06-01

281

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

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

Shekhar, S.

1997-03-01

282

Complementary slip distributions of 200 years of megathrust earthquakes  

NASA Astrophysics Data System (ADS)

Coral paleo-geodesy on the Mentawai Islands off western Sumatra has produced a multi-seismic-cycle geodetic record which provides physical constraints on the slip distributions of large and great earthquakes. Using a Monte Carlo forward modelling method we have estimated the slip on the great 1797 and 1833 earthquakes and show that their most likely slip distributions are not only complementary but leave unruptured areas on the megathrust which appear to have been filled by the M8.4 and 7.9 Bengkulu earthquakes and the M7.8 Pagai earthquake. These results are consistent with a model in which slip in future earthquakes is controlled not only by secular loading and stress interaction between recent earthquakes, but also by the stress footprints of previous earthquakes potentially over many earthquake cycles. We discuss these results in the context of recent great earthquakes and suggest a mathematical formalism which unites observations of the evolution of slip deficit through heterogeneous tectonic loading, seismic and aseismic slip over many earthquakes. We apply the method to the Mentawai region including 330 years of heterogeneous loading of the Sunda megathrust and slip due to more than 30 historical and instrumentally recorded earthquakes. This complex slip deficit field is heterogeneous not only in the strain energy but also in the resolution and we introduce a new technique to clearly visualise both. We show that these results are consistent with the well published threat of a large tsunamigenic earthquake off western Sumatra and make some comments on constraining the threat.

McCloskey, J.; NicBhloscaidh, M.; Naylor, M.

2012-12-01

283

Modelling Paleoearthquake Slip Distributions using a Gentic Algorithm  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

284

Spatial relation between main earthquake slip and its aftershock distribution  

NASA Astrophysics Data System (ADS)

We examine where aftershocks occur relative to the spatial distribution of the main shock slip using data from several recent large earthquakes. No universal relation between high- and low-moment regions and high or low aftershock occurrence, or vice versa, is found. We generally find that few, and usually the smaller, aftershocks occur in the high-slip regions of the fault, a notable exception to this being the great 1996 Biak, Indonesia, subduction zone earthquake. In all cases, aftershocks occur on favorably oriented planes of weakness in regions of increased postseismic stress. Generally, they are clustered at both ends of faults, but examples where aftershocks occur only at one end or where there is no clustering at the ends are found. Aftershock clusters are also found at the edge of unbroken barriers, and regions of rapid transition from high to low slip, within the main fault area. We identify examples of geometrical and inhomogeneous barriers and sharp and dull stress concentrations. Rupture in the main shock is generally found to nucleate in the region of low slip or at the edge of high-slip regions, the 1996 Biak earthquake again being the only exception, nucleating in a very high slip region. Off-fault aftershocks are found for all earthquakes in this study, and they sometimes rupture the nodal plane conjugate to the main shock fault plane.

Das, S.; Henry, C.

2003-09-01

285

Holocene slip rate along the Gyaring Co Fault, central Tibet  

NASA Astrophysics Data System (ADS)

Although geodetic measurements of interseismic deformation in interior Tibet suggest slow strain accumulation, active slip along the right-lateral Gyaring Co Fault is suggested to be between 8 and 21 mm/yr. Reliable geologic constraints on the slip rate along this fault are sparse. Here we document 12 ± 2 m of right-lateral displacement of lacustrine shorelines across the Gyaring Co Fault. Optically stimulated luminescence ages of the shorelines are tightly clustered between 4.1 and 4.4 ka. These data require an average slip rate of 2.2-3.2 mm/yr along the central Gyaring Co Fault during the latter half of the Holocene. Consideration of seismic cycle effects allows the possibility of slightly higher average slip rates, up to 2.2-4.5 mm/yr. Overall, our results suggest that the slip rate along the Gyaring Co Fault is similar to other strike-slip faults in interior Tibet, supporting the notion that active deformation in this region is distributed among numerous, slowly moving faults.

Shi, Xuhua; Kirby, Eric; Lu, Haijian; Robinson, Ruth; Furlong, Kevin P.; Wang, Erchie

2014-08-01

286

Effects of Aging on the Biomechanics of Slips and Falls  

PubMed Central

Although much has been learned in recent decades about the deterioration of muscular strength, gait adaptations, and sensory degradation among older adults, little is known about how these intrinsic changes affect biomechanical parameters associated with slip-induced fall accidents. In general, the objective of this laboratory study was to investigate the process of initiation, detection, and recovery of inadvertent slips and falls. We examined the initiation of and recovery from foot slips among three age groups utilizing biomechanical parameters, muscle strength, and sensory measurements. Forty-two young, middle-age, and older participants walked around a walking track at a comfortable pace. Slippery floor surfaces were placed on the track over force platforms at random intervals without the participants’ awareness. Results indicated that younger participants slipped as often as the older participants, suggesting that the likelihood of slip initiation is similar across all age groups; however, older individuals’ recovery process was much slower and less effective. The ability to successfully recover from a slip (thus preventing a fall) is believed to be affected by lower extremity muscle strength and sensory degradation among older individuals. Results from this research can help pinpoint possible intervention strategies for improving dynamic equilibrium among older adults. PMID:16553061

Lockhart, Thurmon E.; Smith, James L.; Woldstad, Jeffrey C.

2010-01-01

287

Effects of Perturbation-Based Slip Training Using a Virtual Reality Environment on Slip-induced Falls.  

PubMed

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

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

2014-09-23

288

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...

289

Palaeoearthquake surface rupture inatransition zone fromstrike-slip to oblique-normal slip and its implications to seismic hazard, North Island Fault System, New Zealand  

Microsoft Academic Search

The North Island Fault System (NIFS) is the longest and highest slip-rate active strike-slip fault system within the Hikurangi subduction margin in New Zealand, accommodating up to 10 mm\\/a of the margin-parallel plate motion. Displacement of landforms over the lastc. 30 ka indicates a gradual northward change from right-lateral strike-slip to oblique-normal slip along the northern NIFS and within 60

VASILIKI MOUSLOPOULOU; ANDREW NICOL; TIMOTHY A. LITTLE; JOHN G. BEGG

290

Modeling shallow slip deficit in large strike-slip earthquakes using simulations of spontaneous earthquake sequences in elasto-plastic media  

Microsoft Academic Search

Slip inversions of several large strike-slip earthquakes point to coseismic slip deficit at shallow depths (< 3-5 km), i.e., the amount of coseismic slip sharply decreases towards the Earth surface (e.g., Fialko et al., 2005; Bilham, 2010). Examples include the 1992 M7.3 Landers earthquake, the 1999 M7.1 Hector Mine earthquake, the 2005 M6.5 Bam earthquake, the 2010 M7.0 Haiti earthquake,

Y. Kaneko; Y. Fialko

2010-01-01

291

Electromagnetic emissions during seismic nucleation phase of stick-slips  

NASA Astrophysics Data System (ADS)

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

Onuma, K.; Otsuki, K.

2008-12-01

292

Regional Slip Tendency Analysis of the Great Basin Region  

SciTech Connect

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.

Faulds, James E.

2013-09-30

293

Slip deficit and frictional properties on the San Andreas fault at Parkfield inferred from mechanical models of interseismic and postseismic slip  

Microsoft Academic Search

We invert GPS data to estimate the distribution of interseismic slip deficit rate and frictional properties on the San Andreas fault at Parkfield using mechanical models of interseismic and postseismic slip. Interseismic slip deficit distribution is estimated using a new hybrid-mechanical\\/kinematic model. In this model, fault patches are assumed to be either fully locked or creeping at constant resistive shear

J. Fukuda; K. M. Johnson

2006-01-01

294

Nucleation and triggering of earthquake slip: effect of periodic stresses  

USGS Publications Warehouse

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

Dieterich, J.H.

1987-01-01

295

Slip Running Reconnection in Magnetic Flux Ropes  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

297

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

298

Granular and semi-brittle descriptions of slip and creep  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

299

Late Quaternary Slip Rates of the Sumatran Fault  

NASA Astrophysics Data System (ADS)

The Sumatran Fault accommodates a large portion of the right-lateral, trench-parallel component of relative motion between the northward-subducting India-Australia plates and the overriding Sunda plate. Slip rate estimates for this strike-slip fault have primarily been calculated by dividing the observed horizontal deflection across the fault trace of river valleys incised into voluminous caldera-derived tuffs by the radiometrically-dated eruption age of those tuffs, or by estimating the age of displaced river valleys from the length of the displaced channels [1]. These slip rates exhibited a dramatic northward increase in trench-parallel relative displacement that would have to be accommodated by trench-parallel stretching of the forearc sliver [2]. We present new slip rate estimates for the Sumatran Fault where it traverses the Toba, Maninjau, and Ranau tuffs in northern, central, and southern Sumatra. We re-mapped the deflected drainage networks using high-resolution satellite imagery, digital topography, and field observations. At Toba, the best-fitting slip rate is 13.8 × 0.3 mm/yr, about half the previously published estimate. At Maninjau, the best-fitting slip rate is 14.8 × 0.4 mm/yr, faster than the previous estimates of ~10-11 mm/yr. While a new slip rate for the Ranau area is pending the results of radiometric dating of the incised tuffs, we mapped lateral displacements of river valleys of ~230 m, much smaller than previously estimated displacement of ~2,500 m. The revised Late Pleistocene slip rates at Toba and Maninjau are similar to each other and compare favourably with recent GPS-derived slip-rate estimates for several segments of the Sumatran Fault, suggesting that ~40% of the trench-parallel displacement between the forearc islands and the backarc is accommodated on structures other than the Sumatran Fault [3], and that this situation has persisted for at least the past 50,000 to 74,000 years. [1](Bellier and Sébrier, GRL v.22, 1995) [2] (McCaffrey, Geology v.19, 1992) [3] (Feng et al., in prep.)

Bradley, K.; Sieh, K.; Natawidjaja, D.; Daryono, M. R.

2013-12-01

300

Nonoperative treatment of slipped capital femoral epiphysis: a scientific study  

PubMed Central

Background Treatment of the Slipped Capital Femoral Epiphysis remains a cause of concern due to the fact that the true knowledge of the etiopathogeny is unknown, as well as one of its major complications: chondrolysis. The conservative treatment remains controversial; it has been overlooked in the studies and subjected to intense criticism. The purpose of this study is to investigate the results of treatment on the hip of patients displaying slipped capital femoral epiphysis, using the plaster cast immobilization method and its link to chondrolysis. Methods The research was performed based on the study of the following variables: symptomatology, and the degree of slipping. A hip spica cast and bilateral short/long leg casts in abduction, internal rotation with anti-rotational bars were used for immobilizing the patient's hip for twelve weeks. Statistical analysis was accomplished by Wilcoxon's marked position test and by the Fisher accuracy test at a 5% level. Results A satisfactory result was obtained in the acute group, 70.5%; 94%; in the chronic group (chronic + acute on chronic). Regarding the degree of the slipping, a satisfactory result was obtained in 90.5% of hips tested with a mild slip; in 76% with moderate slip and 73% in the severe slip. The statistical result revealed that a significant improvement was found for flexion (p = 0.0001), abduction (p = 0.0001), internal rotation (p = 0.0001) and external rotation (p = 0.02). Chondrolysis was present in 11.3% of the hips tested. One case of pseudoarthrosis with aseptic capital necrosis was presented. There was no significant variation between age and chondrolysis (p = 1.00).Significant variation between gender/non-white patients versus chondrolysis (p = 0.031) and (p = 0.037), respectively was verified. No causal association between plaster cast and chondrolysis was observed (p = 0.60). In regard to the symptomatology group and the slip degree versus chondrolysis, the p value was not statistically significant in both analyses, p = 0.61 and p = 0.085 respectively. Conclusions After analyzing the nonoperative treatment of slipped capital femoral epiphysis and chondrolysis, we conclude that employment of the treatment revealed that the method was functional, efficient, valid, and reproducible; it also can be used as an alternative therapeutic procedure regarding to this specific disease. PMID:21333019

2011-01-01

301

Mechanical analysis of fault slip data: Implications for paleostress analysis  

NASA Astrophysics Data System (ADS)

Stress inversions are a useful and popular tool for structural geologist and seismologist alike. These methods were first introduced by Wallace (1951) and Bott (1959) and subsequent studies continue to be based on their assumptions: the remote stress tensor is spatially uniform for the rock mass containing the faults and temporally constant over the history of faulting in that region, and the slip on each fault surface has the same direction and sense as the maximum shear stress resolved on that surface from the remote stress tensor. Furthermore, successful implementation requires that slip accumulates on faults of diverse orientation. Many studies employ these methods on isolated faults or on fault systems with limited ranges of orientations, which can lead to erroneous results. We propose a new method that incorporates the effects of mechanical interaction of the entire fault or fault system, and solves the complete mechanical problem rather than employing empirical relationships between slip and stress or strain (or strain rate). The method requires knowledge of the fault geometry and information on at least one slip vector component along portions of the known fault geometry. For example, if throw is known, the strike-slip component can be solved for. We test the method using a single synthetic fault with anisotropic roughness similar to that measured at fault outcrops. While the orientation of remote stress may be determined precisely, the lack of diverse fault orientations introduces a systematic error in the remote stress ratio. We further test the effect of diversity of fault orientations and find that Wallace-Bott type inversions do not perform as well for limited ranges of orientations when compared to the proposed method. Finally, we use published data from the 1999 Chi-Chi, Taiwan, earthquake, and find that the method using surface data only, and surface data with subsurface focal mechanisms, produce similar results. The resulting stress orientations are in good agreement with results from Wallace-Bott inversions. Furthermore, the slip distribution is in general agreement with kinematic slip inversions using coseismic surface deformation. Stress inversion methods using fault slip data can thus be improved upon, significantly in some cases, by solving a mechanical boundary value problem that takes into account the geometry of faults or fault systems. As a bonus, the solution provides the stress, strain, and displacement fields throughout the region and the slip distributions on the faults.

Kaven, J. O.; Maerten, F.; Pollard, D. D.

2011-02-01

302

Torsional Stick-Slip Behavior in WS2 Nanotubes  

NASA Astrophysics Data System (ADS)

We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (WS2). When an external torque is applied to a WS2 nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. This is contrary to what happens in a multi-wall carbon nanotube, where an external torque causes the outer wall to slip and twist smoothly around the inner walls. We present a theoretical model based on DFTB calculations, which explains the torsional stick-slip behavior of WS2 nanotubes in terms of a competition between the effects of the in-plane shear stiffness of the WS2 walls and the inter-wall friction arising from the atomic corrugation of the interaction between adjacent WS2 walls. K. S. Nagapriya, Ohad Goldbart, Ifat Kaplan-Ashiri, Gotthard Seifert, Reshef Tenne, and Ernesto Joselevich, Phys. Rev. Lett. 101, 195501 (2008).

Nagapriya, K. S.; Goldbart, Ohad; Kaplan-Ashiri, Ifat; Seifert, Gotthard; Tenne, Reshef; Joselevich, Ernesto

2009-03-01

303

Cross-slip Paths and Energetics in Al and Ag  

NASA Astrophysics Data System (ADS)

A new semi-discrete variational approach is developed for the energetics of dislocation cross-slip in FCC metals. In the new model, we let screw dislocations spread into two intersecting planes, glide and cross-slip planes. Within the Peierls-Nabarro formalism, the energy of a given core configuration is then determined by the elastic interaction between two continuously distributed dislocation densities and the associated misfit energies intergrated over the two planes. The ? surfaces entering the model are calculated from the density functional theory. We find an optimal cross-slip path and the associated cross-slip energy barrier in a series of constrained minmization calculations, starting from different initial core configurations. It turns out that screw dislocations in Al an Ag follow different cross-slip paths characterized by very different activation barriers. Our results are compared with the experimental and simulation data available in the literature. Our approach can also be used to study more complicated dislocation reactions over different glide planes.

Lu, Gang; Kioussis, Nicholas; Bulatov, Vasily; Kaxiras, Efthimios

2000-03-01

304

Slip-rate-dependent melt extraction at oceanic transform faults  

NASA Astrophysics Data System (ADS)

Crustal thickness differences between oceanic transform faults and associated mid-ocean ridges may be explained by melt migration and extraction processes. Slow-slipping transform faults exhibit more positive gravity anomalies than the adjacent spreading centers, indicating relative thin crust in the transform domain, whereas at intermediate-spreading and fast-spreading ridges transform faults are characterized by more negative gravity anomalies than the adjacent spreading centers, indicating thick crust in the transform domain. We present numerical models reproducing these observations and infer that melt can be extracted at fast-slipping transforms, but not at slow-slipping ones. Melt extraction is modeled as a three-step process. (1) Melt moves vertically through buoyancy-driven porous flow enhanced by subvertical dissolution channels. (2) Melt accumulates in and travels along a decompaction channel lining a low-permeability barrier at the base of the thermal boundary layer. (3) Melt is extracted to the surface when it enters a melt extraction zone. A melt extraction width of 2-4 km and a melt extraction depth of 15-20 km are needed to fit the tectonic damages associated with oceanic plate boundaries that reach into the upper mantle. Our conclusions are supported by the different degrees of magmatic activities exhibited at fast-slipping and slow-slipping transforms as reflected in geological features, geochemical signals, and seismic behaviors. We also constrain that the maximum lateral distance of crust-level dike propagation is about 50-70 km.

Bai, Hailong; Montési, Laurent G. J.

2015-02-01

305

New concepts from experimental models of strike-slip tectonics  

SciTech Connect

This paper provides a retrospective view of scaled sandbox models of strike-slip faulting, which were carried out over the past 15 years at KSEPL (Shell Research). We present a variety of models which were firstly validated against structures mapped using wells and good quality seismic data, and could then be used to assist seismic interpretations in areas of poor data quality. The models presented have often contributed to a better understanding of regional tectonics, and have led to better definition of structural hydrocarbon traps. In pure strike-slip, the Riedel shear geometry is shown to depend on the initial stress state, interference of parallel basement faults and horizontal layering of the overburden. Above two parallel basement faults, a single wide or two separate fault zones may be mapped, depending on the depth of observation. In a heterogeneous layered sequence. upwards branching of Riedel shears occurs at layer interfaces. In oblique-slip faulting, the sense of vertical displacement and the geometry of the fault pattern are indicative of the tectonic regime. The degree of obliquity of the fault strike can be related to the ratio of dip-slip to strike-slip movement. In the case of relay structures, the ratio of the length of basement-fault offset to the thickness of the overburden controls the geometry of the fault pattern.

Pascal, R.D.; Naylor, M.A. [Shell Research, Rijswijk (Netherlands)

1996-12-31

306

New concepts from experimental models of strike-slip tectonics  

SciTech Connect

This paper provides a retrospective view of scaled sandbox models of strike-slip faulting, which were carried out over the past 15 years at KSEPL (Shell Research). We present a variety of models which were firstly validated against structures mapped using wells and good quality seismic data, and could then be used to assist seismic interpretations in areas of poor data quality. The models presented have often contributed to a better understanding of regional tectonics, and have led to better definition of structural hydrocarbon traps. In pure strike-slip, the Riedel shear geometry is shown to depend on the initial stress state, interference of parallel basement faults and horizontal layering of the overburden. Above two parallel basement faults, a single wide or two separate fault zones may be mapped, depending on the depth of observation. In a heterogeneous layered sequence. upwards branching of Riedel shears occurs at layer interfaces. In oblique-slip faulting, the sense of vertical displacement and the geometry of the fault pattern are indicative of the tectonic regime. The degree of obliquity of the fault strike can be related to the ratio of dip-slip to strike-slip movement. In the case of relay structures, the ratio of the length of basement-fault offset to the thickness of the overburden controls the geometry of the fault pattern.

Pascal, R.D.; Naylor, M.A. (Shell Research, Rijswijk (Netherlands))

1996-01-01

307

Leg length discrepancy in patients with slipped capital femoral epiphysis  

PubMed Central

Background and purpose Leg-length discrepancy (LLD) can be a sequela of slipped capital femoral epiphysis (SCFE). We tried to identify factors that affect the development of LLD following SCFE. Patients and method We evaluated 85 patients who had been treated using percutaneous screw fixation. The average age of the patients at the time of surgery was 12 (8–16) years. The relationship of LLD and various clinical and radiographic parameters was evaluated: the degree of slip, articulotrochanteric distance (ATD), and articulotrochanteric distance difference (ATDD) (healthy side minus the side with SCFE). We assessed the relationship between ATDD and LLD based on scanogram. Results The average LLD was 1.4 (0.1–3.8) cm at 6 (2–15) years postoperatively. 48 of 85 patients had an LLD of greater than 1 cm and 10 patients had an LLD of greater than 2 cm. There was a correlation between the magnitude of LLD and the severity of the slip. There was no statistically significant correlation between LLD and the stability of the slip, age, BMI, sex, or race. There was a significant correlation between LLD and ATDD. Interpretation Patients with a high degree of slip are prone to develop clinically significant LLD. Although ATDD does not give the exact LLD, it can be used as a primary measurement, which should be supplemented with scanogram in cases of clinically significant differences in length. PMID:23594246

2013-01-01

308

Endocrine Dysfunction and Slipped Capital Femoral Epiphysis 1  

PubMed Central

Five patients with concomitant endocrinopathy and slipped capital femoral epiphysis were studied in detail. One had diabetes and hypothyroidism, one had hypothyroidism, one had hypergonadotropic hypogonadism and two had a craniopharyngioma (one of whom had severe panhypopituitarism post-operatively). An additional seven patients with cranio-pharyngioma revealed marked delay in closure of epiphyses and an additional undiagnosed case of slipped capital femoral epiphysis. Of the six patients with slipped capital femoral epiphysis, three had bilateral and three unilateral involvement. Of the five patients undergoing surgical stabilization, there was significant delay of epiphyseodesis, prompting us to recommend concomitant bone grafting. Histological examination of the femoral head from a three year old child with panhypopituitarism showed marked irregularity of the growth plate and loss of columnar integrity, which may be a predisposing factor to slipping in older children with endocrinopathies. The effects of various hormones on the physis are specifically discussed, especially as they relate to the possible etiology of slipped capital femoral epiphysis. ImagesFIG. 1A and 1BFIG. 2FIG. 3A and 3BFIG. 4A and 4BFIG. 5 PMID:191998

Ogden, John A.; Southwick, Wayne O.

1977-01-01

309

Stick-slip nanofriction in trapped cold ion chains  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

310

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

DOEpatents

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

Cleveland, J.R.

1997-03-18

311

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

DOEpatents

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

Cleveland, Joe R. (West Hills, CA)

1997-01-01

312

Does hydraulic-fracturing theory work in jointed rock masses  

SciTech Connect

The hypocenter locations of micro-earthquakes (acoustic emissions) generated during fracturing typically are distributed three-dimensionally suggesting that fracturing stimulates a volumetric region, rather than the planar fracture theoretically expected. The hypocenter maps generated at six operating, or potential, HDR reservoirs in the US, Europe and Japan are examined in detail and the fracture dimensions are correlated with fracture injection volumes and formation permeability. Depsite the volumetric appearance of the maps we infer that the induced fractures are mainly planar and may propagate aseismically. The induced seismicity stems from nearby joints, which are not opened significantly by fracturing, but are caused to shear-slip because of local pore pressure.

Murphy, H.D.; Keppler, H.; Dash, Z.V.

1983-01-01

313

Temporomandibular joint dislocation.  

PubMed

Dislocation of the temporomandibular joint is one of many pathophysiologic joint conditions that the oral and maxillofacial surgeon is challenged with managing. Managing a dislocated joint will inevitably be the challenge of most surgeons or physicians, whether in private or academic practice. Accordingly, this article addresses the pathophysiology associated with dislocation, in addition to treatment strategies aimed at managing acute, chronic, and recurrent dislocation. PMID:25483448

Liddell, Aaron; Perez, Daniel E

2015-02-01

314

Late Quaternary left-lateral slip rate of the Haiyuan fault, northeastern margin of the Tibetan Plateau  

Microsoft Academic Search

Slip rates of major active strike-slip faults within and around the Tibetan Plateau provide constraints for understanding the dynamics of continental deformation in general because large slip rates can be taken to imply localized deformation between rigid blocks and low slip rates on faults are more consistent with distributed deformation. Several major strike-slip faults have been studied during the last

Chuanyou Li; Pei-zhen Zhang; Jinhui Yin; Wei Min

2009-01-01

315

Slip flow over structured surfaces with entrapped microbubbles  

E-print Network

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

Jari Hyväluoma; Jens Harting

2008-05-26

316

Supershear Mach-Waves Expose the Fault Breakdown Slip  

NASA Astrophysics Data System (ADS)

During an earthquake, changes in stresses on the fault and within the surrounding material occur as the fault slips and radiates seismic waves. The radiated energy strongly depends on the way these stresses evolve in the rupture front, where most of dissipative mechanisms concentrate. Thus, any constraint obtained from observations on how tractions drop as the fault slips is crucial for understanding the rupture process and the generation of reliable physics-based model predictions. One of the most important parameters controlling the strength drop is the breakdown slip, Dc, which is defined as the slip required by the shear traction to progress from its peak value to its residual value during rupture. Mikumo et al. (2003) showed that it is possible to estimate Dc as the slip at the time of the peak slip rate for rupture propagation with subshear speeds. Fukuyama and Mikumo (2007) later attempted to extend this method off the fault to extract information about Dc from strong-motion records due to ruptures propagating at subshear speeds. However, a reasonably accurate estimate of Dc in this rupture regime is only possible within a case-dependent narrow zone adjacent to the fault. The length of this zone, Rc, is comparable to the length of the fault cohesive zone where the breakdown process takes place, and approximately equal to 80% of the wavelength associated with the breakdown frequency (Cruz-Atienza et al., 2009). When the rupture propagates with supershear speeds, on the other hand, this energy is carried much farther away from the fault by Mach waves, in particular Rayleigh Mach-waves when rupture reaches the Earth’s surface. Here, we present a new approach to estimate Dc from strong-motion records containing Mach-waves (Cruz-Atienza and Olsen, 2010). First, we show that the method by Mikumo et al. is valid for supershear rupture propagation. This method is then used to estimate Dc via an asymptotic approximation of the slip and slip-rate time histories from Mach-waves recordings. Using 3D spontaneous rupture simulations we demonstrate that, for a visco-elastic half-space model, Dc can be estimated with an accuracy of 40% from Mach-waves that have propagated a distance of at least 3 km from the fault. The method is applied to estimate Dc for the 2002 Mw7.9 Denali, Alaska, earthquake (~1.5 m) and for the 1999 Mw7.6 Izmit, Turkey, earthquake (~1.7 m). REFERENCES: 1) Cruz-Atienza, V.M., K.B. Olsen, and L.A. Dalguer (2009). Estimation of the breakdown slip from strong-motion seismograms: insights from numerical experiments Bull. Seismol. Soc. Am., 99, 3454-3469, doi:10.1785/0120080330. 2) Cruz-Atienza, Víctor M. and Kim B. Olsen. Supershear Mach-Waves Expose the Fault Breakdown Slip, Tectonophysics (2010), doi:10.1016/j.tecto.2010.05.012. 3) Fukuyama, E., Mikumo T., 2007. Slip-weakening distance estimated at near-fault stations, Geophys. Res. Lett., 34, doi:10.1029/2006GL029203. 4) Mikumo, T., K.B. Olsen, E. Fukuyama, and Y. Yagi (2003). Stress-breakdown time and critical weakening slip inferred from the source time functions on earthquake faults, Bull. Seismol. Soc. Am. 93, 264-282.

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

2010-12-01

317

Quantum Nucleation of Phase Slips in 1-d Superfluids  

NASA Astrophysics Data System (ADS)

The rate for quantum nucleation of phase slips past an impurity in a one-dimensional superfluid is computed. Real time evolution of the nonlinear Schrödinger equation shows that there is a critical velocity vc below which solutions are time-independent [1,2]; this is the regime of quantum phase slip nucleation. We start with the Gross-Pitaevskii model in the presence of an impurity potential, and derive the Euclidean action for a space-time vortex-antivortex pair, which describes a phase slip event. The action is computed as a function of the superfluid velocity v and the impurity potential width and depth.l [1] V. Hakim, Phys. Rev. E 55, 2835 (1997).l [1] J. A. Freire, D. P. Arovas, and H. Levine, Phys. Rev. Lett (in press, 1997).l

Arovas, Daniel

1998-03-01

318

ETS and tidal stressing: Fault weakening after main slip pulse  

NASA Astrophysics Data System (ADS)

Time-varying stresses from solid Earth tides and ocean loading influence slow slip (Hawthorne and Rubin, 2010) and, consequently, the frequency of occurrence and intensity of tremor during ETS episodes (Rubinstein et al., 2008). This relationship can illuminate changes in the mechanical response of the rupture surfaces(s) during slip in ETS. I compare the influence of tidal loading when and after the propagating ETS slip front (estimated by tremor density in time) ruptures the fault at a given spot. Using estimates of slip fronts that I derived from tremor locations, I divide ETS tremor into two groups: that occurring within a day of the start of the inferred slip front and that occurring over several days thereafter. The tremor catalog used contains 50K waveform cross-correlation locations of tremor in 7 large ETS in northern Cascadia between 2005 and 2012. I calculate normal, shear and volumetric stresses due to the Earth and ocean tides at numerous locations on the inferred rupture plane of the ETS following the method of Hawthorne and Rubin (2010). The Coulomb stress increment at each tremor time and location is compared with tremor occurrence for the two groups of tremor. Unreasonable results appear if the effective frictional coefficient mu > 0.2, and results are most 'reasonable' when mu is very near or equal to zero. Following passage of the main slip pulse, tremor generation is notably more sensitive to tidal stressing. One kPa of encouraging tidal Coulomb stress boosts the occurrence of tremor after the main slip pulse by about 50% above the average value, while the same amount of discouraging stress decreases the occurrence of such tremor by a similar factor. The greater the encouraging or discouraging stress, the greater the effect. In contrast, tremor in the main slip pulse is much less affected by positive or negative tidal stresses. I interpret the greater sensitivity to tidal stressing of the tremor after the main slip pulse as a measure of the weakening of the fault plane following its initial rupture. Considering up- and down-dip sensitivities to tidal stress, tremor generation on the up-dip region is affected roughly 50% more by both positive and negative tidal stresses than tremor down-dip. Furthermore, for the down-dip tremor, there is less contrast in sensitivity to stress between the tremor at the main slip front and the later tremor, i.e., the fault downdip is both less sensitive to tidal stress and weakens less due to the rupture. These results are consistent with the timing and geometry of Rapid Tremor Reversals, which also indicate weakening of the fault after the main slip front has passed through a region (Houston et al., 2011). RTRs occur on updip parts of the fault, after the main slip front, and at times of encouraging tidal stress (Thomas et al., 2013).

Houston, H.

2013-12-01

319

Slip-boundary equations for multicomponent nonequilibrium airflow  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

320

Surface-slip equations for multicomponent nonequilibrium air flow  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

321

Surface-slip equations for multicomponent, nonequilibrium air flow  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

322

Preliminary soil-slip susceptibility maps, southwestern California  

USGS Publications Warehouse

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

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

2003-01-01

323

Superplastic flow lubricates carbonate faults during earthquake slip  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

324

Geodetic data inversion using ABIC to estimate slip history during one earthquake cycle with viscoelastic slip-response functions  

NASA Astrophysics Data System (ADS)

We developed a new method of geodetic data inversion to estimate slip history at a plate interface by using Akaike's Bayesian Information Criterion (ABIC). In this method we considered the effects of viscoelastic stress relaxation in the asthenosphere, which cannot be neglected to estimate slip history at a plate interface during one earthquake cycle. We also introduced a proper formulation to incorporate two sorts of partially dependent prior information into observed data by Bayes' rule. By applying the new inversion method to levelling data for 1893-1983 in Shikoku, southwestern Japan, we reconstructed the pattern of space-time variation in slip motion during one earthquake cycle, including the 1946 Nankai earthquake, at the interface between the Eurasian and the Philippine Sea plates. The result shows that a steady slip motion at a plate convergence rate (40 mm yr-1) proceeds in the shallow and the deep regions through the entire earthquake cycle. In the intermediate depth range (10-30 km), on the other hand, an instantaneous slip of approximately 4 m occurs at the time of the Nankai earthquake. After that, this portion keeps in stationary contact until the occurrence of the next Nankai earthquake. If we neglect the effects of viscoelastic stress relaxation, the inversion analysis gives geophysically unrealistic results.

Fukahata, Yukitoshi; Nishitani, Akira; Matsu'ura, Mitsuhiro

2004-01-01

325

Possible Stick-Slip Mechanism for Whillans Ice Stream  

NASA Technical Reports Server (NTRS)

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.

Bindschadler, Robert; King, Matt; Vornberger, Patricia

2003-01-01

326

Reduced Aftershock Productivity in Regions with Known Slow Slip Events  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

327

Global strike-slip faults: Bounds from plate tectonics  

NASA Astrophysics Data System (ADS)

According to the tenets of plate tectonics, a transform fault is a strike-slip fault along which neither convergence nor divergence occurs. Analysis of global plate motion data indicates that the only true transform faults are the strike-slip faults that offset segments of mid-ocean ridges. Thus, many of Earth's major strike-slip fault systems are not true transform faults as they accommodate large components of oblique convergence or oblique divergence. This is particularly true for several important ocean-continent systems such as the San Andreas, the strike-slip systems bounding the northern and southern Caribbean plate, the Alpine fault system of New Zealand, the Anatolian fault system, and the Azores-Gibraltar-Alboran sea system. These strike-slip systems are commonly sites of large scale mountain building and basin formation. Here we examine the far-field constraints on the motions of the plates bounding several of these strike-slip systems using both conventional plate motion circuits and results from global positioning system and other space geodetic data. We pay particular attention to the San Andreas fault system in central and northern California, where the San Andreas system is part of the boundary between the Sierran microplate and the Pacific plate. Most of the fault system accommodates obliquely convergent motion, giving rise to the California Coast Range, but in the northern San Francisco Bay Area it is obliquely divergent, producing San Pablo Bay and a gap in the Coast Range that permits the Sierran watershed to drain to the Pacific through the Golden Gate.

Gordon, R. G.; Argus, D. F.

2006-12-01

328

Bilateral unstable slipped capital femoral epiphysis: a look at risk factors.  

PubMed

Unstable slipped capital femoral epiphysis can have disastrous complications including osteonecrosis and chondrolysis. It has been shown that 20% to 80% of patients may develop a contralateral slip ?18 months after diagnosis. The purpose of this article is to report and characterize patients who developed bilateral unstable slips. After Institutional Review Board approval, the patients included were only those with bilateral unstable slipped capital femoral epiphyses. A minimum 2-year follow-up was required. Seven patients, all female, were included in the study, with an average age of 11.4 years at the time of their first slips. The interval between slips averaged 127 days (range, 0-245 days). All but 1 patient presented with a severe slip. The second slip was also severe in 3 patients and less severe in 4 patients. The triradiate cartilage was open in 3 patients. Two patients required corrective osteotomies. Chondrolysis developed in 2 patients with no osteonecrosis reported. The incidence of bilateral unstable slips ranged from 4% to 20% of all unstable slipped capital femoral epiphyses based on our findings. Skeletal immaturity was not a risk factor. The surgeon must be vigilant for the possibility of bilateral slips. The family must be instructed on precautions patients must take while recuperating from unstable slipped capital femoral epiphyses. Contralateral fixation of the unaffected side may be warranted in patients with initial severe unstable slipped capital femoral epiphyses to prevent this condition. PMID:21667895

Herrera-Soto, José A; Vanderhave, Kelly L; Gordon, Eric; Fabregas, Jorge; Phillips, Jonathan H; Schoenecker, Perry; Parsch, Klaus

2011-06-01

329

Rate and state variable friction laws: Estimation of model parameters for slip velocity dependence at coseismic slip rates  

NASA Astrophysics Data System (ADS)

In the present study plate-impact pressure-shear friction experiments are conducted to study dynamics of high-speed slip at metal-on-metal interfaces. By using a CH tool-steel/Ti-6Al-4V tribo-pair and appropriate selection of the flyer and target plate thicknesses, the experiment has been used to investigate the frictional resistance of sliding interfaces subjected to step changes in slip rates. In order to describe the frictional memory effects a model based on Ruina-Dieterich slip law has been utilized. It is noted that the model parameter a in the range of 0.01-0.25 with characteristic lengths of L =5-7 ?m provides a reasonably good fit to the experimental data.

Prakash, Vikas

2009-12-01

330

Campylobacter Prosthetic Joint Infection  

PubMed Central

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

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

2014-01-01

331

Behavior of jointed pipelines  

Microsoft Academic Search

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

Singhal

1984-01-01

332

Wedge Joints for Trusses  

NASA Technical Reports Server (NTRS)

Structure assembled rapidly with simple hand tools. Proposed locking wedge joints enable rapid assembly of lightweight beams, towers, scaffolds, and other truss-type structures. Lightweight structure assembled from tubular struts joined at nodes by wedge pins fitting into mating slots. Joint assembled rapidly by seating wedge pin in V-shaped slots and deforming end of strut until primary pawl engages it.

Wood, Kenneth E.

1987-01-01

333

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

NASA Astrophysics Data System (ADS)

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.

Maruyama, Tadashi; Lin, Aiming

2004-05-01

334

Strategies for joint appointments.  

PubMed

The structure and policies governing joint appointments discussed above, are developed primarily through cooperation and collaboration between nursing service and education institutions. The joint appointee participates in the process of negotiation of salary, benefits and role responsibilities and exploration of the implications of the appointment for personal career development. Implementation and maintenance of the appointment requires the collaborative efforts of the joint appointee with both contracting agencies. Factors influencing the functioning of joint appointees have been identified and strategies to facilitate functioning presented. The joint appointee must be independent in thought and action yet adaptable to work within the boundaries of two social systems with differing values and expectations. Nursing management, peers and students can provide the support needed to overcome the frustrations and to achieve the rewards inherent in successful implementation of an exciting and innovative role. PMID:3852805

Royle, J; Crooks, D L

1985-01-01

335

Simultaneous Dislocation of Radiocapitellar and Distal Radioulnar Joint  

PubMed Central

A 45-year-old male presented to the emergency room of our institution complaining of severe pain around the left elbow. While playing volleyball, he slipped down with his left arm hit between the floor and his body. He complaind of strong pain from left elbow to hand, and active motion of elbow and wrist joint was impossible. His forearm was held in supinated position. On X-ray examination, radius head was deviated to anterior lateral side, and distal end of radius was dislocated to dorsal side. Tenderness was prominent at the site of radial head and distal radioulnar joint. Surgical treatment was performed using triceps tendon strip. Good functional recovery was gained. PMID:24194995

Nishi, Tomio; Suzuki, Noriyuki; Tani, Takayuki

2013-01-01

336

Stick-slip instabilities and shear strain localization in amorphous materials Eric G. Daub  

E-print Network

on stick-slip instabilities, which are responsible for earthquake slip on seismic faults, noise from automobile brakes and tires, music from a violin, and excessive wear on frictional interfaces in machinery

Carlson, Jean

337

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

338

Charge-Related SQUID and Tunable Phase-Slip Flux Qubit  

NASA Astrophysics Data System (ADS)

A phase-slip flux qubit, exactly dual to a charge qubit, is composed of a superconducting loop interrupted by a phase-slip junction. We propose a tunable phase-slip flux qubit by replacing the phase-slip junction with a charge-related superconducting quantum interference device (SQUID) consisting of two phase-slip junctions connected in series with a superconducting island. This charge-SQUID acts as an effective phase-slip junction controlled by the applied gate voltage and can be used to tune the energy-level splitting of the qubit. In addition, we show that a large inductance inserted in the loop can reduce the inductance energy and consequently suppress the dominating flux noise of the phase-slip flux qubit. This enhanced phase-slip flux qubit is exactly dual to a transmon qubit.

Zhao, Hu; Li, Tie-Fu; Liu, Jian-She; Chen, Wei

2014-03-01

339

SH Wave Scattering from Fractures using Boundary Element Method with Linear Slip Boundary Condition  

E-print Network

A boundary element method (BEM) combined with a linear slip boundary condition is proposed to calculate SH wave scattering from fractures. The linear slip boundary condition was proposed by Schoenberg (1980) to model elastic ...

Chen, Tianrun

2011-01-01

340

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

USGS Publications Warehouse

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

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

2005-01-01

341

Micro-Vibration-Based Slip Detection in Tactile Force Sensors  

PubMed Central

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

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

2014-01-01

342

Slip modelling and aided inertial navigation of an LHD  

Microsoft Academic Search

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

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

1997-01-01

343

Stress-Strain Curves and Slip Bands of KCl Whiskers  

Microsoft Academic Search

Tensile tests were made, at room temperature, on KCl whiskers grown on outer surfaces of thin cellophane bags containing saturated aqueous solution. It was found that their stress-strain curves consist of four deformation stages. Slip bands were straight in the early stage of deformation, but rumpled surfaces were observed in the later stages under an optical microscope. Deformed specimen showed

Kazuhiko Yoshida

1965-01-01

344

Multi-Modal Monitoring of Slip Along Frictional Discontinuities  

NASA Astrophysics Data System (ADS)

Seismic wave transmission and digital image correlation (DIC) are employed to study slip processes along frictional discontinuities. A series of biaxial compression experiments are performed on gypsum specimens with non-homogeneous contact surfaces. The specimens are composed of two blocks with perfectly mated contact surfaces with a smooth surface with low frictional strength on the upper half and a rough surface with high frictional strength on the lower half. Compressional, P, and shear, S, wave pulses were transmitted through the discontinuity while digital images of the specimen surface were acquired during the test. A distinct peak in the amplitude of transmitted wave occurs prior to the peak shear strength and is considered a "precursor" to the failure. Precursors indicate that slip initiates from the smooth surface and extends to the rough surface as the shear load is increased. From the DIC data, slip is identified as a jump in the displacement field along the fracture that initiates from the smooth surface and propagates to the rough surface. Precursors are associated with an increase in the rate of slip across the discontinuity and are a measure of the reduction in the fracture shear stiffness.

Hedayat, Ahmadreza; Pyrak-Nolte, Laura J.; Bobet, Antonio

2014-09-01

345

Chaotic mixing in a planar, curved channel using periodic slip  

E-print Network

We propose a novel strategy for designing chaotic micromixers using curved channels confined between two flat planes. The location of the separatrix between the Dean vortices, induced by centrifugal force, is dependent on the location of the maxima of axial velocity. An asymmetry in the axial velocity profile can change the location of the separatrix. This is achieved physically by introducing slip alternatingly at the top and bottom walls. This leads to streamline crossing and Lagrangian chaos. An approximate analytical solution of the velocity field is obtained using perturbation theory. This is used to find the Lagrangian trajectories of fluid particles. Poincare sections taken at periodic locations in the axial direction are used to study the extent of chaos. The extent of mixing, for low slip and low Reynolds numbers, is shown to be greater when Dean vortices in adjacent half cells are counter-rotating. Wide channels are observed to have much better mixing than tall channels; an important observation not made for separatrix flows till now. Eulerian indicators are used to gauge the extent of mixing with varying slip length and it is shown that an optimum slip length exists which maximizes the mixing in a particular geometry.

P. Garg; J. R. Picardo; S. Pushpavanam

2014-11-24

346

An Analysis of Strain Accumulation on a Strike Slip Fault  

Microsoft Academic Search

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

D. L. Turcotte; D. A. Spence

1974-01-01

347

Analysing earthquake slip models with the spatial prediction comparison test  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

348

Slip acceleration generates seismic tremor like signals in friction experiments  

E-print Network

Slip acceleration generates seismic tremor like signals in friction experiments Dimitri Zigone,1 nearly a decade ago, the origin of seismic tremor remains unclear. Recent studies indicate that various driving phenomena such as Earth and ocean tides, regional and teleseismic earthquakes enhance tremor

349

Enhancing the dexterity of a robot hand using controlled slip  

Microsoft Academic Search

An analysis was performed of controlled slipping of an object within a robot hand. The possible ways an object can move within a grasp were enumerated. The set of permissible motions was found as a function of the constraint state, that is, the number, location, and types of contact on an object. The constraint state was found as a function

David L. Brock

1988-01-01

350

Clutch slip control of Automatic Transmission using nonlinear method  

Microsoft Academic Search

To improve the shift quality of vehicle with clutch-to-clutch gear shifts, a nonlinear controller is designed for the clutch slip control during the shift inertia phase of an Automatic Transmission (AT). Backstepping technique is used to deduce the control algorithm. Model uncertainties including steady state errors and unmodelled dynamics are also considered as additive disturbance inputs and the controller is

Bingzhao Gao; Hong Chen; Yan Ma; Kazushi Sanada

2009-01-01

351

Modeling of viscoelastic shear: A nonlinear stick-slip formulation  

E-print Network

Modeling of viscoelastic shear: A nonlinear stick-slip formulation H.T. Banks and Negash G. Medhin 53201-0413 February 20, 2006 Abstract We present a class of nonlinear dynamic viscoelastic models internal dynamics for shear deformations in viscoelastic materials. The resulting partial differential

352

Automated fault model discretization for inversions for coseismic slip distributions  

Microsoft Academic Search

Geoscientists increasingly rely on coseismic slip distributions inferred from geodetic observations to drive sophisticated models of the seismic cycle. To date, little work has been done on optimizing the parameterization of these fault models so that they reflect the resolving power of observed surface displacements. The locations of noisy surface displacement observations are often widely scattered far from features we

W. D. Barnhart; R. B. Lohman

2010-01-01

353

Well packers and slip assemblies for use therewith  

Microsoft Academic Search

There is disclosed an hydraulically set well packer wherein sleeves carried about a tubular member which is connected as part of a tubing string are adapted to be moved from axially extended to axially retracted position in order to expand packing and slip elements carried about one of the sleeves into engagement with the well bore in which the string

Akkerman

1983-01-01

354

Continuum mathematical modeling of slip weakening in geological systems  

E-print Network

may occur either slowly by creep and/or differential slippage as well as by sudden rupture [Bolt, 1970 to describe the strength degradation within the fault zone during the initial stage of slip instability or the creation of a new one depending on the current loading direction. The shear strength then decays to a lower

Borja, Ronaldo I.

355

Chaotic mixing in a planar, curved channel using periodic slip  

NASA Astrophysics Data System (ADS)

We propose a novel strategy for designing chaotic micromixers using curved channels confined between two flat planes. The location of the separatrix between the Dean vortices, induced by centrifugal forces, is dependent on the location of the maxima of axial velocity. An asymmetry in the axial velocity profile can change the location of the separatrix. This is achieved physically by introducing slip alternatingly at the top and bottom walls. This leads to streamline crossing and Lagrangian chaos. An approximate analytical solution of the velocity field is obtained using perturbation theory. This is used to find the Lagrangian trajectories of fluid particles. Poincare sections taken at periodic locations in the axial direction are used to study the extent of chaos. We study two microchannel designs, called circlet and serpentine, in which the Dean vortices in adjacent half cells are co-rotating and counter-rotating, respectively. The extent of mixing, at low Re and low slip length, is shown to be greater in the serpentine case. Wide channels are observed to have much better mixing than tall channels; an important observation not made for separatrix flows till now. Eulerian indicators are used to gauge the extent of mixing, with varying slip length, and it is shown that an optimum slip length exists which maximizes the mixing in a particular geometry. Once the parameter space of relatively high mixing is identified, detailed variance computations are carried out to identify the detailed features.

Garg, P.; Picardo, J. R.; Pushpavanam, S.

2015-03-01

356

Interfacial Slip in Entrained Soap Films Containing Associating Hydrosoluble Polymer  

E-print Network

Interfacial Slip in Entrained Soap Films Containing Associating Hydrosoluble Polymer Eric A 6, 2004 Frankel's law predicts that the thickness of a Newtonian soap film entrained at small that soap films containing low concentrations of high molecular weight (Mw) polymer can exhibit strong

Troian, Sandra M.

357

Stokes shear flow over a grating: Implications for superhydrophobic slip  

NASA Astrophysics Data System (ADS)

A semianalytical model based on the method of eigenfunction expansions and domain decomposition is developed for Stokes shear flow over a grating composed of a periodic array of parallel slats, with finite slippage on solid surfaces and infinite slippage on the bottom of troughs mimicking a no-shear liquid-gas interface penetrating into the space between slats. The model gives the macroscopic slip lengths for flow parallel or normal to the slats in terms of the microscopic slip length of the liquid-solid interface, area fraction of the no-shear liquid-gas interface, and depth of the liquid-gas interface in the grooves. When the no-shear interface lies flat on the top of the slats, the macroscopic slip lengths are the maximum and can be estimated with reasonably good accuracy by simple formulas. However, the slip lengths, particularly the transverse one, are very sensitive to penetration of the no-shear interface into the grooves. They can be reduced by a large factor when the interface just slightly gets into the grooves. On comparing with some molecular-dynamics simulation measures, it is pointed out that the applied pressure, which has to be less than the capillary pressure in the superhydrophobic state, can be correlated with the penetration depth of the no-shear interface.

Ng, Chiu-On; Wang, C. Y.

2009-01-01

358

Slip Surface Localization in Wireless Sensor Networks for Landslide Prediction  

E-print Network

Slip Surface Localization in Wireless Sensor Networks for Landslide Prediction Andreas Terzis Applied Physics Lab Johns Hopkins University Laurel, MD 20723 I-Jeng.Wang@jhuapl.edu ABSTRACT A landslide understood, prediction of landslides has been hin- dered thus far by the lack of field measurements over

Amir, Yair

359

Supporting Information for Digital PCR on a SlipChip  

E-print Network

Average # per quadrant Score based 95% CI range Rounded 95% CI 1 fg/µL Upper Left Upper Right Lower Left Society of Chemistry 2010 #12;Table S1. Number of positive wells in each quadrant of the SlipChip for various concentrations of genomic DNA and agreement with the 95% CI. Number of positive wells in quadrant

Ismagilov, Rustem F.

360

Slip-based tire-road friction estimation  

Microsoft Academic Search

An approach to estimate the tire-road friction during normal drive using only the wheel slip, that is, the relative difference in wheel velocities, is presented. The driver can be informed about the maximum friction force and be alarmed for sudden changes. Friction-related parameters are estimated using only signals from standard sensors in a modern car. An adaptive estimator is presented

Fredrik Gustafsson

1997-01-01

361

Three-dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip  

Microsoft Academic Search

Fault processes involve complex patterns of seismic events and aseismic slip. This work develops a three-dimensional (3-D) methodology for simulating long-term history of spontaneous seismic and aseismic slip on a vertical planar strike-slip fault subjected to slow tectonic loading. Our approach reproduces all stages of earthquake cycles, from accelerating slip before dynamic instability, to rapid dynamic propagation of earthquake rupture,

Nadia Lapusta; Yi Liu

2009-01-01

362

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

NASA Astrophysics Data System (ADS)

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

Reches, Zeev; Chang, Jefferson

2013-04-01

363

Regional Slip Tendency Analysis of the Great Basin Region  

DOE Data Explorer

- 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.

Faulds, James E.

364

The liquid metal slip ring experiment for the communications technology satellite  

NASA Technical Reports Server (NTRS)

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.

Lovell, R. R.

1972-01-01

365

Evidence for Quaternary Slip on a Low Angle Normal Fault: Searles Valley, CA  

Microsoft Academic Search

Low angle normal faults have been documented in extensional terranes worldwide, however conventional models of fault mechanics preclude slip on planes dipping less than 30 degrees. The global catalogue of earthquake focal mechanisms reveals very few occurrences of seismicity (active slip) on low angle structures, lending support to mechanical arguments against active slip on shallowly dipping planes. Recent field studies

T. Numelin; E. Kirby

2004-01-01

366

Wall slip of molten high density polyethylene. I. Sliding plate rheometer studies  

Microsoft Academic Search

Experiments were performed in a sliding plate rheometer with a high density polyethylene to determine the conditions for the onset of slip and the relation- ship between slip velocity and shear stress. It was found that melt slip occurs at a critical shear stress of approximately 0.09 MPa in both steady and transient shear tests. The effect of the presence

S. G. Hatzikiriakos; J. M. Dealy

1991-01-01

367

Rheological study of polymer flow past rough surfaces with slip boundary conditions  

E-print Network

and weak wall-fluid interactions, the shear rate dependence of the slip length has a distinct local minimum to the adjacent solid wall and the shear rate with the proportional- ity coefficient, the slip length, which structure,13,14 and shear rate.15­17 However, the experi- mental determination of the slip length

Priezjev, Nikolai V.

368

Slip Correction Measurements of Spherical Solid Aerosol Particles in an Improved Millikan Apparatus  

Microsoft Academic Search

A slip correction factor is used to correct Stokes' law for the fact that the no-slip boundary condition is violated for small aerosol particles moving with respect to the gaseous medium. The Knudsen-Weber form of the slip correction is given by C(Kn)= 1 + Kn[? + ? exp(—?\\/Kn)]. The parameters ?, ?, and ? are customarily those based upon the

Michael D. Allen; Otto G. Raabe

1985-01-01

369

Seismic slip deficit in the Kashmir Himalaya from GPS observations Celia Schiffman1  

E-print Network

1 Seismic slip deficit in the Kashmir Himalaya from GPS observations Celia Schiffman1.5±1 mm/yr) includes 50% sinistral range parallel shear). · The slip deficit in the 270-km-long Kashmir wide and terminates in a ~23 km wide and 25±4 km deep partially locked zone. · Cumulative slip deficit

Bilham, Roger

370

Dilatant strengthening as a mechanism for slow slip events Paul Segall,1  

E-print Network

a fraction of plate motion; the remaining deficit must be accommodated during coseismic or postseismic slipDilatant strengthening as a mechanism for slow slip events Paul Segall,1 Allan M. Rubin,2 Andrew M; published 3 December 2010. [1] The mechanics of slow slip events (SSE) in subduction zones remain unresolved

371

Repeated large Slow Slip Events at the southcentral Alaska subduction zone  

NASA Astrophysics Data System (ADS)

We identify and study an ongoing Slow Slip Event (SSE) in the southcentral Alaska subduction zone using GPS measurements. This is the second large SSE in this region since modern geodetic measurements became available in 1993. We divide the ongoing SSE into two phases according to their transient displacement time evolution; their slip distributions are similar to each other but slip rates are slightly different. This ongoing SSE occurs downdip of the main asperity that ruptured in the 1964 Alaska earthquake, on the same part of the subduction interface as the earlier 1998-2001 SSE. The average slip rate of this SSE is ?4-5 cm/yr, with a cumulative moment magnitude of Mw 7.5 (Mw 7.3 and Mw 7.1 For Phases I and II, respectively) through the end of 2012. The time and space dependence of the GPS displacements suggest that the slip area remained nearly the same during Phase I, while the slip rate increased with time. The SSEs occur on a transitional section of the subduction plate interface between the fully locked updip part and the freely slipping deeper part. During the 1964 earthquake, slip on the region of the SSE was much lower than slip in the updip region. Based on this observation and the repeated SSEs, we conclude that this part of the interface slips repeatedly in SSEs throughout the interseismic period and does not build up a large slip deficit to be released through large slip in earthquakes.

Fu, Yuning; Freymueller, Jeffrey T.

2013-08-01

372

Slip rates and seismic moment deficits on major active faults in mainland China  

E-print Network

Slip rates and seismic moment deficits on major active faults in mainland China Hui Wang,1,2 Mian faults and intensive seismic activity; both can be described in terms of slip rates on these faults. Previous studies of fault slip rates in mainland China have focused on individual faults or fault segments

Liu, Mian

373

Current Science (2004) 1 Apparent Himalayan slip deficit from the summation of  

E-print Network

Current Science (2004) 1 Apparent Himalayan slip deficit from the summation of seismic moments/yr). The missing slip is equivalent to four Mw>8.5 earthquakes, events that are unlikely to have escaped note explanations for the missing slip, ranging from the extreme view that large earthquakes are in our future

Bilham, Roger

374

Constraints on fault and lithosphere rheology from the coseismic slip and postseismic afterslip  

E-print Network

slip deficit was at least partly recovered by postseismic afterslip on the shallow part of the faultConstraints on fault and lithosphere rheology from the coseismic slip and postseismic afterslip°). The amount of slip in the earthquake decreased from depths of $10 km toward the surface, and this shallow

375

Spectralelement simulations of longterm fault slip: Effect of lowrigidity layers on earthquakecycle  

E-print Network

basins) on the nature of shallow coseismic slip deficit. Our results suggest that lowrigidity shallow layers alone do not lead to coseismic slip deficit. While the lowrigidity layers result in lowerSpectralelement simulations of longterm fault slip: Effect of lowrigidity layers on earthquakecycle

Lapusta, Nadia

376

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

E-print Network

Cascadia megathrust and contrast with slip deficits implied by earthquake recurrence intervals from. Accumulating this slip deficit requires 360­400 years at the plate convergence rate, exceeding the 330-year Cascadia turbidite record. By comparison, slip deficits inferred from time intervals separating earthquake

Goldfinger, Chris

377

Very high cycle fatigue of copper: Evolution, morphology and locations of surface slip markings  

E-print Network

Very high cycle fatigue of copper: Evolution, morphology and locations of surface slip markings N cycle fatigue Persistent slip bands Grain boundaries Strain localization Fatigue limit The surfaces high cycle fatigue regime were investigated. The stress amplitude needed to form the early slip

Paris-Sud XI, Université de

378

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

E-print Network

EXPERIMENTAL ANALYSIS OF GROUNDWATER FLOW THROUGH A LANDSLIDE SLIP SURFACE USING NATURAL,Tric, Emmanuel,Bertrand, Catherine Mudry, Jacques Keywords: Hydromechanics, tracer test, landslides, slip surface measurements are conducted on a small landslide with a well known slip surface geometry. Outflow yields

Paris-Sud XI, Université de

379

Water flow and slip on NAPL-wetted surfaces of a parallel-walled fracture  

Microsoft Academic Search

The effects of various wetting conditions and aperture sizes on water flow and slip in a parallel-walled fracture were investigated. Water flow experiments showed that a larger slip occurred as the surface became more hydrophobic. For a creosote-wetted surface of the fracture with an aperture of 508 ?m, the increase in the water flow rate due to the slip was

Hang-Bok Lee; Kang-Kun Lee

2007-01-01

380

Anelastic processes in strike slip faulting: Application to the San Francisco earthquake of 1906  

Microsoft Academic Search

An analytic approximation to the Green's function for the displacements due to a strike slip point source in an elastic layer over a viscoelastic half space is developed. To represent the quasi-static displacements from a large crustal strike slip earthquake, a model is constructed which makes use of the approximate Green's function. Aseismic slip below the brittle seismic zone is

J. B. Rundle

1976-01-01

381

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

USGS Publications Warehouse

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

Peng, Zhigang; Gomberg, Joan

2010-01-01

382

Giant slip at liquid-liquid interfaces using hydrophobic ball bearings Quentin Ehlinger, Laurent Joly,  

E-print Network

Giant slip at liquid-liquid interfaces using hydrophobic ball bearings Quentin Ehlinger, Laurent by hydrophobic beads behave as ball bearings under shear and exhibit giant slip. Using a scaling analysis. In the following, we show that it is possible to achieve giant slip between two liquids using a bed of hydrophobic

Boyer, Edmond

383

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

E-print Network

Role of friction-induced torque in stick-slip motion J. Scheibert1, and D.K. Dysthe1 1 PGP describing the kinematics of the transition from static friction to stick-slip motion of a linear elastic the precursors to frictional sliding and the periodic stick- slip motion are controlled by the amount of friction

384

Compliant Joints For Robots  

NASA Technical Reports Server (NTRS)

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

Kerley, James J., Jr.

1990-01-01

385

Slip and Dilation Tendency Analysis of the Patua Geothermal Area  

SciTech Connect

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

Faulds, James E.

2013-12-31

386

Long dormancy, low slip rate, and similar slip-per-event for the Emerson fault, eastern California shear zone  

Microsoft Academic Search

Excavations in a playa along the 1992 rupture of the Emerson fault reveal evidence of two paleoseismic events, with only one large prehistoric rupture in the past 15 millennia. Accelerator mass spectrometer radiocarbon ages of charcoal from playa sediments and from fault-scarp colluvium directly beneath the playa beds indicate that the last large prehistoric slip event occurred about 9000 ka.

Charles M. Rubin; Kerry Sieh

1997-01-01

387

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

NASA Astrophysics Data System (ADS)

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

Maury, Julie; Aochi, Hideo; Radiguet, Mathilde

2014-05-01

388

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

NASA Astrophysics Data System (ADS)

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

Kim, Chang-Jin

2009-11-01

389

Culture - joint fluid  

MedlinePLUS

Joint fluid culture ... fungi, or viruses grow. This is called a culture. If such microorganisms are detected, other tests may ... is no special preparation needed for the lab culture. For information on preparing for the removal of ...

390

Healthy Joints Matter  

MedlinePLUS

... caused by a buildup of uric acid (YOOR-ic acid) crystals in the joints, most commonly in ... form of arthritis called psoriatic (sore-ee-AT-ic) arthritis. Rheumatoid arthritis (ROO-muh-toid ar-THRY- ...

391

Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area  

SciTech Connect

Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = ? / ?n (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (?1-?n) / (?1-?3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in 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...

Faulds, James E.

2013-12-31

392

Optimization of bonded joints  

NASA Technical Reports Server (NTRS)

A procedure for minimizing the elastic shear stress concentration in adhesive lap joints is presented. The proposed method is based upon tapering the adherends to achieve smooth stiffness transitions and uniform shear stresses. Both single and double lap splices are considered, but numerical examples are restricted to the case of double lap joints. Nonisotropic materials and nonoptimum design limitations, such as minimum and maximum thickness adherends, load-line eccentricity, and peel stresses are treated, and typical results are presented.

Ojalvo, I. U.

1983-01-01

393

Joint Contact Stress  

PubMed Central

A joint's normal mechanical history contributes to the maintenance of articular cartilage and underlying bone. Loading facilitates the flow of nutrients into cartilage and waste products away, and additionally provides the mechanical signals essential for normal cell and tissue maintenance. Deleteriously low or high contact stresses have been presumed to result in joint deterioration, and particular aspects of the mechanical environment may facilitate repair of damaged cartilage. For decades, investigators have explored static joint contact stresses (under some more or less arbitrary condition) as a surrogate of the relevant mechanical history. Contact stresses have been estimated in vitro in many joints and in a number of species, although only rarely in vivo. Despite a number of widely varying techniques (and spatial resolutions) to measure these contact stresses, reported ranges of static peak normal stresses are relatively similar from joint to joint across species, and in the range of 0.5 to 5.0 MPa. This suggests vertebrate diarthrodial joints have evolved to achieve similar mechanical design criteria. Available evidence also suggests some disorders of cartilage deterioration are associated with somewhat higher peak pressures ranging from 1-20 MPa, but overlapping the range of normal pressures. Some evidence and considerable logic suggests static contact stresses per se do not predict cartilage responses, but rather temporal aspects of the contact stress history. Static contact stresses may therefore not be a reasonable surrogate for biomechanical studies. Rather, temporal and spatial aspects of the loading history undoubtedly induce beneficial and deleterious biological responses. Finally, since all articular cartilage experiences similar stresses, the concept of a "weight-bearing" versus a "non-weight-bearing" joint seems flawed, and should be abandoned. PMID:16089079

Brand, Richard A

2005-01-01

394

Joint hypermobility syndrome pain  

Microsoft Academic Search

Joint hypermobility syndrome (JHS) was initially defined as the occurrence of musculoskeletal symptoms in the presence of\\u000a joint laxity and hypermobility in otherwise healthy individuals. It is now perceived as a commonly overlooked, underdiagnosed,\\u000a multifaceted, and multisystemic heritable disorder of connective tissue (HDCT), which shares many of the phenotypic features\\u000a of other HDCTs such as Marfan syndrome and Ehlers-Danlos syndrome.

Rodney Grahame

2009-01-01

395

High pressure ceramic joint  

DOEpatents

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.

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

1993-11-30

396

Use of two-dimensional transmission photoelastic models to study stresses in double-lap bolted joints  

NASA Technical Reports Server (NTRS)

The stress distribution in two hole connectors in a double lap joint configuration was studied. The following steps are described: (1) fabrication of photoelastic models of double lap double hole joints designed to determine the stresses in the inner lap; (2) assessment of the effects of joint geometry on the stresses in the inner lap; and (3) quantification of differences in the stresses near the two holes. The two holes were on the centerline of the joint and the joints were loaded in tension, parallel to the centerline. Acrylic slip fit pins through the holes served as fasteners. Two dimensional transmission photoelastic models were fabricated by using transparent acrylic outer laps and a photoelastic model material for the inner laps. It is concluded that the photoelastic fringe patterns which are visible when the models are loaded are due almost entirely to stresses in the inner lap.

Hyer, M. W.; Liu, D. H.

1981-01-01

397

Dual megathrust slip behaviors of the 2014 Iquique earthquake sequence  

NASA Astrophysics Data System (ADS)

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.

Meng, Lingsen; Huang, Hui; Bürgmann, Roland; Ampuero, Jean Paul; Strader, Anne

2015-02-01

398

Seismic and aseismic slip on the central Peru megathrust (Invited)  

NASA Astrophysics Data System (ADS)

In the last couple of decades, advances in the analysis techniques and instrumentation have improved significantly our capability to document the different stages of the seismic cycle, namely the co-, post- and inter-seismic phases. To this respect, the Mw8.0 Pisco, Peru, earthquake of August 2007 is exemplary, with numerous data sets allowing exploring the details of each phase and studying their relationship. The post-seismic deformation following the mainshock is studied using a local network of continuous GPS stations together with various InSAR interferograms. Inversion for slip on the fault is carried on using the PCAIM inversion method (http://www.tectonics.caltech.edu/resources/pcaim/). The inversion shows two patches of significant afterslip located near the co-seismic asperities, in agreement with the idea that coseismic slip triggers afterslip. Aftershocks are located on top of the patches of high postseismic slip, while they are anti-correlated with the position of the co-seismic asperities, consistent with the idea that afterslip drive aftershocks. Post-seismic relaxation is consistent with rate and state friction, assuming a rate strengthening rheology. The most prominent of those post-seismic patches coincides with the subducting Nazca ridge, an area also characterized by a locally low interseismic coupling and which seems to have acted as a barrier to seismic rupture propagation repeatedly in the past. The ’seismogenic’ portion of the megathrust thus appears to be paved with interfingering of rate-weakening and rate-strengthening patches. The rate-strengthening patches are shown to contribute to an unsuspected high proportion of aseismic slip and to determine the extent and frequency of large interplate earthquakes. Aseismic slip accounts for as much as 50-70% of the slip budget on the seismogenic portion of the megathrust of central Peru and the return period of Mw 8.0 earthquakes in the Pisco area is estimated to 250 years, a value in good agreement with the 261 years between the 2007 Pisco earthquake and the previous large megathrust earthquake in this area which occurred in 1746.

Perfettini, H.; Avouac, J.; Kositsky, A.; Rémy, D.; Tavera, H.; Nocquet, J.; Chlieh, M.; Sladen, A.

2010-12-01

399

Patterns of Seismic and Aseismic Slip on Heterogeneous Faults  

NASA Astrophysics Data System (ADS)

Geological studies of exhumed faults and seismological observations reveal interesting aspects of fault heterogeneity. We thus carried numerical studies to explore the implications of fault heterogeneity on the organization of seismicity and transient aseismic slip. Our quasi-dynamic, continuum models are based on laboratory derived rate-and-state friction with heterogeneity introduced by spatial distributions of characteristic slip distance (Dc). We considered two types of faults, a simple strike-slip fault and a typical subduction fault; and two types of spatial distribution of Dc, a model with uniformly random log Dc distribution, and a hierarchical model of asperities with self-similar power-law asperity size distribution and Dc value proportional to asperity size. Our systematic study shows that by varying the distribution of Dc value, we are able to reproduce a wide variety of macroscopic fault behaviors ranging from characteristic seismic events to steady-slip. For different combinations of minimum and maximum Dc values on a fault we simulated multiple earthquake cycles with a total duration long enough to characterize the general behavior of the fault: characteristic (regularly repeating events that break the whole fault), non-characteristic (events with a range of magnitudes, in some cases with a complex but repeating pattern), aseismic transients and steady slip. We found that non-characteristic seismicity behavior occurs only over a relatively narrow range of Dc distributions. We extended our study in this regime and observed complex sequences of seismic events ranging over two orders of magnitude of seismic moments. We generated a synthetic catalog containing over 10,000 events and studied their source scaling relations. The catalog shows a transition in the moment magnitude (M0) - rupture area (A) scaling, from M0~A3/2 at low magnitudes to M0~A at large magnitudes, controlled by the effect of the finite seismogenic depth. Our modeling provides promising insight on the connections between the microscopic properties of the heterogeneous fault and the macroscopic behavior of the fault. The transition from seismic to aseismic events and steady-slip in these models may shed light on the transient behaviors of faults.

Luo, Y.; Ampuero, J. P.

2013-12-01

400

Pre- and postseismic slow slip surrounding the 2011 Tohoku-oki earthquake rupture  

NASA Astrophysics Data System (ADS)

Slow (aseismic) slip that accommodates part of the long-term plate motion on subduction megathrusts is thought to be strongly related to the occurrence of large earthquakes on the same fault zone. However, the temporal evolution and spatial distribution of the aseismic slip before major earthquakes and of accelerated postseismic afterslip are largely unconstrained. We estimate cumulative offsets of small repeating earthquakes that are interpreted to reflect the in situ aseismic slip history on the subduction zone offshore northeastern Japan. These data reveal contrasting aseismic slip patterns between the coseismic rupture area of the Mw 9.0 Tohoku-oki earthquake and surrounding portions of the subduction thrust. The rupture area is characterised by low and variable slip rates before 2008, and the slip stopped almost completely after the earthquake. The region surrounding the rupture area exhibited higher aseismic fault slip rates before the earthquake and clear postseismic slip of up to 1.6 m within 9 months following the main shock. The frictional fault properties and complete relief of ambient stress in the central rupture zone of the main shock probably control the observed distribution. The postseismic slip shows a more abrupt increase in the region closer to the source, suggesting outwards propagation of afterslip. Small but distinct increases in the slip rate in the ~3 yr before the earthquake near the area of large coseismic slip suggests preseismic unfastening of the locked area in the last stage of the earthquake cycle.

Uchida, Naoki; Matsuzawa, Toru

2013-07-01

401

The effective slip length and vortex formation in laminar flow over a rough surface  

NASA Astrophysics Data System (ADS)

The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier-Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition is no-slip. By applying a local slip boundary condition, the center of the vortex is displaced toward the bottom of the grooves and the effective slip length increases. When the intrinsic slip length is larger than the corrugation amplitude, the flow streamlines near the surface are deformed to follow the boundary curvature, the vortex vanishes, and the effective slip length saturates to a constant value. Inertial effects promote vortex flow formation in the grooves and reduce the effective slip length.

Niavarani, Anoosheh; Priezjev, Nikolai V.

2009-05-01

402

Historic surface slip along the San Andreas Fault near Parkfield, California  

NASA Astrophysics Data System (ADS)

The Parkfield Earthquake Prediction Experiment is focusing close attention on the 44-km-long section of the San Andreas fault that last ruptured seismically in 1966 (Ms 6.0). The 20-km-long central segment of the 1966 Parkfield rupture, extending from the mainshock epicenter at Middle Mountain southeastward to Gold Hill, forms a 1- to 2-km salient northeastward away from the dominant N40°W strike. Following the 1966 earthquake afterslip, aseismic slip has been nearly constant. Moderate Parkfield earthquakes have recurred on average every 21 years since 1857, when a great earthquake (M?8) ruptured at least as far north as the southern Parkfield segment. Many measurements of slip have been made near Parkfield since 1966. Nevertheless, much of the history of surface slip remained uncertain, especially the total amount associated with the 1966 event. In 1985 we measured accumulated slip on the four oldest cultural features offset by the fault along the 1966 Parkfield rupture segment. We interpret net slip on each feature as a sum of event slip (sum of coseismic and rapid preseismic and postseismic slip) from Parkfield earthquakes and steady interseismic slip as measured over the last 20 years on nearby alinement arrays, creep meters, and trilateration lines. We assumed for each site that event slip was identical for the 1922, 1934, and 1966 Parkfield events and that long-term average rate of interseismic slip was constant between all events. Two fences on the southern segment, southeast of Gold Hill, indicate event slip of 13 and 15 cm and interseismic slip rate of 0.36 and 0.30 cm/yr since 1959 and 1908, respectively. At these sites, redundant independent data support our assumption that both event and interseismic slip occur uniformly. On the central segment, near Parkfield, both the 1934 and the 1966 ruptures offset a bridge built in 1932. Interseismic slip rate near the bridge has been about 1.1 cm/yr since 1966; thus we deduce an average event slip of 31 cm for the 1934 and 1966 earthquakes. On a parallel fault trace, 1 km to the southwest, slip was about 8 cm in 1966; thus total event slip summed across the entire fault zone near Parkfield was nearly 40 cm. On Middle Mountain, 4 km north of the 1966 mainshock epicenter, an offset fence indicates 17 cm of slip in 1966 and a 2.26-cm/yr interseismic slip rate since circa 1946. Thus the central segment of the 1966 rupture is characterized by much larger event slip (˜40 cm) than both distal segments (˜15 cm). This amount of surface slip per event is about twice what had been previously assumed. Larger 1966 surface slip in the central part of the rupture is geodetically compatible with a coseismic slip of 65±10 cm slip on a narrow, buried asperity between Middle Mountain and Gold Hill that has been inferred from the depth distribution of early aftershocks. Assuming our characteristic surface slip model, one can further deduce a deficit in slip since the great 1857 earthquake. Taking the long-term slip rate as 3.3 cm/yr, the surface slip deficit is 3±0.2 m south of Gold Hill but only 0.3±0.3 m northward from Parkfield.

Lienkaemper, J. J.; Prescott, W. H.

1989-12-01

403

Slip-induced conservation laws for dislocation structures in the finite kinematic framework  

NASA Astrophysics Data System (ADS)

In the present paper we develop a general framework that captures topological, geometric, and energetic aspects of slip surfaces to provide conservation laws for dislocation structures. In this work, dislocations act as the boundary of active slip regions that support a finite displacement jump, while treating the material outside the slip regions with a continuum mechanic framework in the setting of large deformations. Within this semicontinuous description, it is shown that the condition of slip imposes an important restriction on the shape of the slip surfaces regardless of the material structure. This catalog of shapes for the slip surfaces can be further restricted for crystalline materials, providing a simple geometric description of common dislocation processes such as cross slip or dislocation loop glide. In this setting, the classical Kirchhoff-type rule for the conservation of the Burgers vector emanates directly from the formulation, while recent conservation laws designed for partial dislocations in face centered cubic crystals are also naturally captured.

Reina, Celia; Marian, Jaime

2014-09-01

404

Wall-mass effects on hydrodynamic boundary slip.  

PubMed

This paper investigates the combined effects of surface stiffness ? and wall particles' mass m(w) on the slip length. It aims to enhance our understanding of the momentum and energy transfer across solid-liquid interfaces. Elastic spring potentials are employed to simulate the thermal solid walls and model the surface stiffness ?. The thermal oscillation amplitude is primarily dictated by values of stiffness, whereas the oscillating frequency is proportional to ?(?/m(w)). It is shown that for cases with variable wall mass the relation of slip length and thermal oscillating frequencies can be approximated by a "master" curve according to which the length initially increases, then approaches a peak value, and afterwards is reduced toward an asymptotic value. PMID:22060376

Asproulis, Nikolaos; Drikakis, Dimitris

2011-09-01

405

Cytoplasmic streaming in plant cells: the role of wall slip  

E-print Network

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.

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

2012-02-29

406

Competition between shear banding and wall slip in wormlike micelles  

E-print Network

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.

Paul Lettinga; Sébastien Manneville

2009-11-24

407

Electroosmosis of Powell-Eyring fluids under interfacial slip.  

PubMed

We investigate the EOF of a Powell-Eyring fluid through a slit microchannel, employing Navier slip boundary condition. Using an analytical scheme consistent with the homotopy perturbation method, we bring out the alteration in the underlying flow dynamics as attributable to the nonlinear interactions between fluid rheology and electrostatics over interfacial scales. We validate the approximate analytical solutions by comparing those with results from numerical analysis. We unveil a regime of phenomenal amplification in the net volumetric flow rate, realized as a consequence of an intricate interplay between interfacial electromechanics, slipping hydrodynamics, and the flow rheology. Our results may have far ranging consequences in the design of various biomicrofluidic devises/systems, which are often used for the manipulation of non-Newtonain fluids. PMID:25502924

Goswami, Prakash; Kumar Mondal, Pranab; Dutta, Sanmitra; Chakraborty, Suman

2015-03-01

408

Slipped upper tibial epiphysis in infantile tibia vara: three cases.  

PubMed

We describe three cases of infantile tibia vara resulting from an atraumatic slip of the proximal tibial epiphysis upon the metaphysis. There appears to be an association between this condition and severe obesity. Radiologically, the condition is characterised by a dome-shaped metaphysis, an open growth plate and disruption of the continuity between the lateral borders of the epiphysis and metaphysis, with inferomedial translation of the proximal tibial epiphysis. All patients were treated by realignment of the proximal tibia by distraction osteogenesis with an external circulator fixator, and it is suggested that this is the optimal method for correction of this complex deformity. There are differences in the radiological features and management between conventional infantile Blount's disease and this 'slipped upper tibial epiphysis' variant. PMID:22933505

Sanghrajka, A P; Hill, R A; Murnaghan, C F; Simpson, A H R W; Bellemore, M C

2012-09-01

409

Deterministic chaos in a simulated sequence of slip events on a single isolated asperity  

NASA Astrophysics Data System (ADS)

Numerical simulation of repeated occurrences of slip events on a fault patch (asperity) is used to interpret the mechanism of irregular sequences of slip events. The fault is uniformly shear loaded at a constant rate, and the frictional stress acting on the fault is assumed to obey a rate- and state-dependent friction (RSF) law. A circular patch with velocity-weakening frictional property is embedded in the fault, which apart from this has velocity-strengthening frictional property. The numerical simulations are conducted using various characteristic slip distances L of the RSF law. For small values of L seismic slip events (earthquakes) repeatedly occur at regular intervals. With increasing L, the recurrence of slip events becomes more complex. A period doubled slip pattern, where seismic and aseismic slip events alternately occur, multiperiodic patterns and aperiodic patterns occur. At the same time, slip tends to become aseismic with increasing L. The distributions of shear stress on the fault just before slip events are variable because of variation in the residual stress of the preceding slip event and the shear stress generated by aseismic sliding during interseismic periods. These variations in shear stress cause the complex sequence of slip events seen here. An iteration map of the recurrence intervals of slip events for an aperiodic sequence of slip events is expressed by a simple curve, indicating that the timing of an event is predictable from the previous time interval, and the sequence of slip events exhibits deterministic chaos. To help interpret these results for a sequence of slip events on a velocity-weakening patch embedded in a velocity-strengthening region, a numerical simulation is conducted of slip on a velocity-weakening patch enclosed by a permanently locked region. In this case, no complex recurrence of slip events is observed. When L is less than a critical value, seismic slip events repeatedly occur at a constant interval. Stable sliding occurs when L is larger than the critical value. This result indicates that the complex slip behaviour seen for a velocity-weakening patch embedded in a velocity-strengthening region is caused by the interaction between the velocity-weakening and velocity-strengthening regions.

Kato, Naoyuki

2014-08-01

410

Composite slip table of dissimilar materials for damping longitudinal modes  

DOEpatents

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.

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

1991-01-01

411

Controlling the deformation behavior of thermoplastic slips with ultrasound  

Microsoft Academic Search

The effect of ultrasound on the deformation properties of thermoplastic slips was investigated. It was shown that in treatment\\u000a with ultrasound, the change in the plastic strength of beryllium oxide — thermoplastic binder casting system in the process\\u000a temperature range (40–55°C) was due to cavitation and dissipative heat release effects and can be characterized with the equation\\u000a for a thermal

S. A. Shakhov

2007-01-01

412

Harmonic analysis of slip energy recovery induction motor drives  

SciTech Connect

The impact of drives on the power system in terms of harmonic generation is becoming increasingly important. Slip energy recover induction motor drives (SERIMDs) have the rectifier and inverter connected to the rotor instead of the stator (the case in most conventional drives). The harmonic content of the SERIMD is thus quite different and arguably, less onerous than conventional drives. This paper examines the harmonic content of key waveforms of SERIMDs. Predicted results are supported by extensive experimental results.

Refoufi, L. (Inst. National D'Electricite, Boumerdes (Algeria)); Pillay, P. (Univ. of New Orleans, LA (United States). Dept. of Electrical Engineering)

1994-12-01

413

Translationally Invariant Slip-Spring Model for Entangled Polymer Dynamics  

NASA Astrophysics Data System (ADS)

The topological effect of noncrossability of long flexible macromolecules is effectively described by a slip-spring model, which represents entanglements by local, pairwise, translationally invariant interactions that do not alter any equilibrium properties. We demonstrate that the model correctly describes many aspects of the dynamical and rheological behavior of entangled polymer liquids, such as segmental mean-square displacements and shear thinning, in a computationally efficient manner. Furthermore, the model can account for the reduction of entanglements under shear.

Chappa, Veronica C.; Morse, David C.; Zippelius, Annette; Müller, Marcus

2012-10-01

414

FerrySlipRd. OceanViewDr.  

E-print Network

ADVANTAGE OF NEWPORT'S LOOP BUS Conveniently zip to all of Newport's hot spots in our year round Loop Bus of the lighthouse, enjoy up close views of seabird nesting areas, and explore the year round tide pools. Beach combOSUDrive FerrySlipRd. 32nd OceanViewDr. Edenview 20th 15th Sam Case School Pool 12th 7th 6th 3rd

415

The no-slip boundary condition in fluid mechanics  

Microsoft Academic Search

A moving fluid in contact with a solid body cannot have velocity relative to the body. Even though the question whether there\\u000a is slip has been satisfactorily resolved now, it was a difficult and controversial problem. In the first part of this article\\u000a several basic ideas and details related to this problem are discussed. The concluding part of the article

Sandeep Prabhakara; M. D. Deshpande

2004-01-01

416

Models for Gaseous Slip Flow in Non-Circular Microchannels  

Microsoft Academic Search

Micro-scale fluid dynamics has received intensive interest due to the emergence of Micro-Electro-Mechanical Systems (MEMS) technology. Non-circular cross sections are common channel shapes that can be produced through a variety of micro-fabrication techniques. Non-circular microchannels have extensive practical applications in MEMS. Slip flow in non- circular microchannels has been examined by the authors and a review of several new models

Zhipeng Duan; Y. S. Muzychka

2007-01-01

417

Velocity dependence of serpentinite friction promotes aseismic slip on faults  

SciTech Connect

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.

Reinen, L.A.; Weeks, J.D.; Tullis, T.E. (Brown Univ., Providence, RI (United States). Dept. of Geological Sciences)

1992-01-01

418

a Theoretical Investigation of Axially Loaded Face Center Cubic Crystals in Multiple Slip Positions at Finite Strain  

Microsoft Academic Search

Closed form solutions for critical strengths of slip systems in face centered cubic (f.c.c.) type crystals are obtained for double slip taking place on a common slip plane and on distinct slip planes. These equations are based on the \\

Satish Annaji Salpekar

1982-01-01

419

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

E-print Network

slip estimates for the southern 10 Cascadia megathrust and contrast with slip deficits implied lake outlet to satisfy geological evidence of inundation. Accumulating this slip deficit 20 requires. By comparison, slip 25 deficits inferred from time intervals separating earthquake-triggered turbidites

Goldfinger, Chris

420

Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit  

E-print Network

is therefore an end-member case of a shallow slip deficit model postulating that the coseismic slip in the up be impeded in the shallow crust, it is not clear how the resulting deficit of shallow slip is ac- commodatedThree-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip

Fialko, Yuri

421

Chronic slipped capital femoral epiphysis: a radiographic evaluation of the Southwick osteotomy.  

PubMed

The aim of this study was to evaluate the radiographic correction and the complications in Southwick osteotomy for slipped capital femoral epiphysis (SCFE) on the basis of radiographic evaluation. We retrospectively analyzed the charts of 37 patients with chronic, unilateral, moderate, or severe SCFE, who underwent the procedure, verifying Southwick angles, articulotrochanteric distance, and the articular narrowing on preoperative, postoperative periods, and in the last follow-up evaluation, using the contralateral, healthy hip, for comparison. Southwick's angle changed from 117.8 to 147.3° on average (front) and from 56.9 to 19.1° (Lauenstein view). Articulotrochanteric distance changed from 11.3 to 24.1 mm (normal distance 22.1 mm). Joint space changed from 4.3 mm preoperatively to 3.84 mm. Chondrolysis was diagnosed in five cases before and eight cases after surgery. There was no case of avascular necrosis. Southwick osteotomy effectively corrected SCFE deformity. There was a tendency toward excessive valgism. PMID:23995088

Lino, Wilson; Akkari, Miguel; Waisberg, Gilberto; Braga, Susana R; Santili, Cláudio

2013-11-01

422

Squeaking with a sliding joint: mechanics and motor control of sound production in palinurid lobsters.  

PubMed

The origin of arthropod sound-producing morphology typically involves modification of two translating body surfaces, such as the legs and thorax. In an unusual structural rearrangement, I show that one lineage of palinurid lobsters lost an antennal joint articulation, which transformed this joint from moving with one degree of freedom into a sliding joint with multiple degrees of freedom. With this sliding joint, 'stick-and-slip' sounds are produced by rubbing the base of each antenna against the antennular plate. To understand the musculo-skeletal changes that occurred during the origin and evolutionary variation of this sound-producing mechanism, I examined joint morphology and antennal muscle anatomy across sound-producing and non-sound-producing palinurids. Plectrum movement and antennal muscle activity were measured in a sound-producing species, Panulirus argus. The promotor muscle pulls the plectrum over the file during sound-producing and non-sound-producing movements; a higher intensity of muscle activity is associated with sound production. The promotor muscle is larger and attaches more medially in sound-producing palinurids than in non-sound producers. In Panulirus argus, each shingle on the file has an additional ridge; in Palinurus elephas, the shingle surfaces are smooth. These differences in shingle surface features suggest variation in the stick-and-slip properties of the system. Translational motion permitted by the sliding joint is necessary for sound production; hence, the construction of a sliding joint is a key modification in the origin of this sound-producing mechanism. PMID:12124363

Patek, Sheila N

2002-08-01

423

Dissimilar metals joint evaluation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

424

Acromioclavicular Joint Injuries  

PubMed Central

Objective: To discuss the anatomy and biomechanics of the acromioclavicular (AC) joint, along with the clinical evaluation and treatment of an athlete with an AC joint injury. Data Sources: I searched MEDLINE from 1970 through 1999 under the key words “acromioclavicular joint,” “clavicle,” “acromioclavicular separation,” and “acromioclavicular dislocation.” Knowledge base was an additional source. Data Synthesis: AC joint injury is common in athletes and a source of significant morbidity, particularly for athletes in overhead sports. Because this injury can masquerade as other shoulder conditions, the examiner must understand the anatomy a