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1

Complex Fault Interaction in the Yuha Desert  

NASA Astrophysics Data System (ADS)

We determine precise hypocentral locations for over 3,600 aftershocks that occurred in the Yuha Desert (YD) region following the 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) earthquake until 14 June 2010 originally located by the Southern California Seismic Network (SCSN). To calculate precise hypocenters we used manually identified phase arrivals and cross-correlation delay times in a series of absolute and relative relocation procedures with algorithms including hypoinverse, velest and hypoDD. We used velest to simultaneously invert for station corrections and the best-fitting velocity model for the event and station distribution. Location errors were reduced with this process to ~20 m horizontally and ~80 m vertically. The locations reveal a complex pattern of faulting with en echelon fault segments trending toward the northwest, approximately parallel to the North American-Pacific plate boundary and en echelon, conjugate features trending to the northeast. The relocated seismicity is highly correlated with the mapped faults that show triggered surface slip in response to the EMC mainshock. Aftershocks are located between depths of 2 km and 11 km, consistent with previous studies of seismogenic thickness in the region. Three-dimensional analysis reveals individual and intersecting fault planes between 5 km and 10 km in the along-strike and along-dip directions. These fault planes remain distinct structures at depth, indicative of conjugate faulting, and do not appear to coalesce onto a through-going fault segment. We observe a complex spatiotemporal migration of aftershocks with individual fault strands that are often active for relatively short time periods. In addition, events relocated by Hauksson et al., (2012) that occur in the two-year period following the 15 June 2010 M5.7 Ocotillo earthquake show majority of seismicity occurred along the Laguna Salada-West branch. At the same time, seismicity along the Laguna Salada-East and other faults in the Yuha Desert abruptly shuts off suggesting fault activity is highly sensitive to local stress conditions. To further our investigation, we locate over 15,000 previously unreported aftershocks in the YD during the same time period. For this analysis we detect arrivals using an STA/LTA filter from data continuously recorded on 8 seismometers installed in the YD from 6 April through 14 June 2010. Event association was performed with the Antelope software package. Absolute locations were first determined with hypoinverse using the automated phase picks, and the velocity model used in the above relocation procedure. We refined the relative locations using the automated detections and cross-correlation delay times in hypoDD. We use these newly detected earthquakes to further the investigation of fault geometry at the surface and how it relates to fault structure at depth, rheology of the crust, and the spatiotemporal migration patterns within the aftershock distribution.

Kroll, K.; Cochran, E. S.; Richards-Dinger, K. B.; Sumy, D. F.

2012-12-01

2

Mangroves of Laguna Joyuda.  

National Technical Information Service (NTIS)

Laguna Joyuda mangroves provide opportunity to explore relations beween site factors other than climate and mangrove structure and dynamics. Our analysis reviews (1) the area and environment of Laguna Joyuda mangroves, (2) forest structure, (3) litter dyn...

A. E. Lugo J. C. Musa

1993-01-01

3

Quaternary palaeohydrological evolution of a playa lake: Salada Mediana, central Ebro Basin, Spain  

Microsoft Academic Search

Sedimentary features, mineralogy, bulk geochemical composition, stable isotope analyses and pollen data from sediment cores were used to reconstruct the Late Quaternary depositional evolution of the Salada Mediana playa lake (central Ebro Basin, northeastern Spain). The 150-cm- long sediment core sequence is composed of gypsum- and dolomite-rich muds (Lower and Middle sections) and black, laminated, calcite-bearing sediments (Upper section). The

BLAS L. V ALERO-GARCES; A NTONIO DELGADO-HUERTAS; A NA N AVAS

2000-01-01

4

Provenance of alluvial fan deposits to constrain the mid-term offsets along a strike-slip active fault: the Elsinore fault in the Coyote Mountains, Imperial Valley, California.  

NASA Astrophysics Data System (ADS)

The lateral variation in rates along a fault and its constancy along time is a matter of discussion. To give light to this discussion, short, mid and long term offset distribution along a fault is needed. Many studies analyze the short-term offset distribution along a strike-slip fault that can be obtained by the analysis of offset features imprinted in the morphology of the near-fault area. We present an example on how to obtain the mid- to long-term offset values based on the composition of alluvial fans that are offset by the fault. The study area is on the southern tip of the Elsinore fault, which controls the mountain front of the Coyote Mountains (California). The Elsinore-Laguna Salada fault is part of the San Andreas fault (SAF) system, extending 250 km from the Los Angeles Basin southeastward into the Gulf of California, in Mexico. The slip-rate on the southern Elsinore fault is believed to be moderate based on recent InSAR observations, although a recent study near Fossil Canyon (southern Coyote Mountains) suggests a rate in the range of 1-2 mm/yr. For this study we processed the airborne LiDAR dataset (EarthScope Southern & Eastern California, SoCal) to map short to mid-term alluvial offsets. We reprocessed the point clouds to produce DEMs with 0.5m and 0.25m grids and we varied the insolation angles to illuminate the various fault strands and the offset features. We identified numerous offset features, such as rills, channel bars, channel walls, alluvial fans, beheaded channels and small erosional basins that varied in displacement from 1 to 350 m. For the mid- to long-term offsets of the alluvial fans we benefited from the diverse petrological composition of their sources. Moreover, we recognized that older alluvium, which is offset by greater amounts, is in some cases buried beneath younger alluvial fan deposits and separated by buried soils. To determine the source canyon of various alluvial elements, we quantified the clast assemblage of each source basin and each alluvial fan on both sides of the fault. To accomplish this, we used a portable grid and classified more than 300 clasts at each of more than 90 sites along the fault. We found a very good fit between displaced alluvial fan elements and their inferred source canyons, but a poor match with the alluvium from neighboring canyons, which allows us to resolve the long-term offset. Planned dating of the pedogenic carbonate associated with these buried soils will allow the resolution of the mid- to long-term slip rates over multiple time frames to test the constancy of fault slip rate during the late Quaternary, as well as to test the lateral variations in rate along the fault.

Masana, Eulalia; Stepancikova, Petra; Rockwell, Thomas

2013-04-01

5

Bloedite sedimentation in a seasonally dry saline lake (Salada Mediana, Spain)  

NASA Astrophysics Data System (ADS)

Salt crusts covering the surface of the Salada Mediana, a seasonally dry saline lake in northern Spain, consist predominantly of bloedite (Na 2Mg(SO 4) 2.4H 2O). Microscopic features of the crust were investigated to understand processes of bloedite sedimentation. This study was combined with satellite and airborne observations, revealing asymmetrical concentric and parallel-linear patterns, related to wind action. Gypsum (CaSO 4.H 2O) and glauberite (Na 2Ca(SO 4) 2) in the calcareous sediments below the crust, and abundant eugsterite (Na 4Ca(SO 4) 3.2H 2O) along the base of the crust, largely formed at a different stage than bloedite. The main part of the crust consists predominantly of coarse-crystalline xenotopic-hypidiotopic bloedite, but fan-like aggregates with downward widening, radial aggregates, surface layers with vertically aligned elongated crystals, and partially epitaxial coatings occur as well. The upper part of the crust is marked by a bloedite-thenardite (Na 2SO 4) association, recording a change in brine composition that is not in agreement with results of modelling of local brine evolution. A thin fine-grained thenardite-dominated surface formed in part by subaqueous settling of crystals, but there are also indications for development by transformation of bloedite. Surface features include fan-like bloedite aggregates with upward widening, formed by bottom growth. Overall, the Salada Mediana crusts record a complex history of bloedite and thenardite precipitation by various processes.

Mees, Florias; Castañeda, Carmen; Herrero, Juan; Van Ranst, Eric

2011-06-01

6

Advantages of locating LAGUNA in Pyhäsalmi mine  

NASA Astrophysics Data System (ADS)

LAGUNA is the next-generation underground Megaton-scale detector for the search for proton decay, for neutrino astrophysics and for the investigation of neutrino properties. A brief description of the three considered detector technologies is given and the main physics goals presented. While many of the research topics for LAGUNA are not affected by the geographical location of the detector, there are two areas where it is very important: low-energy neutrino measurements and long-baseline neutrino oscillations. Evaluation of the physics arguments in both cases indicates Pyhäsalmi mine as the best European site for LAGUNA.

Trzaska, W. H.; Enqvist, T.; Joutsenvaara, J.; Kalliokoski, T.; Kokko, E.; Kuusiniemi, P.; Loo, K.; Maalampi, J.; Nuijten, G.; Räihä, T.; Risikko, T.; Roinisto, J.; Rummukainen, K.; Sarkamo, J.

2011-04-01

7

Diversity and distribution of Halomonas in Rambla Salada, a hypersaline environment in the southeast of Spain.  

PubMed

We have studied the diversity and distribution of Halomonas populations in the hypersaline habitat Rambla Salada (Murcia, southeastern Spain) by using different molecular techniques. Denaturing gradient gel electrophoresis (DGGE) using specific primers for the 16S rRNA gene of Halomonas followed by a multivariate analysis of the results indicated that richness and evenness of the Halomonas populations were mainly influenced by the season. We found no significant differences between the types of samples studied, from either watery sediments or soil samples. The highest value of diversity was reached in June 2006, the season with the highest salinity. Furthermore, canonical correspondence analysis (CCA) demonstrated that both salinity and pH significantly affected the structure of the Halomonas community. Halomonas almeriensis and two denitrifiers, H. ilicicola and H. ventosae were the predominant species. CARD-FISH showed that the percentage of Halomonas cells with respect to the total number of microorganisms ranged from 4.4% to 5.7%. To study the functional role of denitrifying species, we designed new primer sets targeting denitrification nirS and nosZ genes. Using these primers, we analyzed sediments from the upwelling zone collected in June 2006, where we found the highest percentage of denitrifiers (74%). Halomonas ventosae was the predominant denitrifier in this site. PMID:24164442

Oueriaghli, Nahid; González-Domenech, Carmen M; Martínez-Checa, Fernando; Muyzer, Gerard; Ventosa, Antonio; Quesada, Emilia; Béjar, Victoria

2014-02-01

8

Present-day loading rate of faults in southern California and northern Baja California, Mexico, and post-seismic deformation following the M7.2 April 4, 2010, El Mayor-Cucapah earthquake from GPS Geodesy  

NASA Astrophysics Data System (ADS)

We use 142 GPS velocity estimates from the SCEC Crustal Motion Map 4 and 59 GPS velocity estimates from additional sites to model the crustal velocity field of southern California, USA, and northern Baja California, Mexico, prior to the 2010 April 4 Mw 7.2 El Mayor-Cucapah (EMC) earthquake. The EMC earthquake is the largest event to occur along the southern San Andreas fault system in nearly two decades. In the year following the EMC earthquake, the EarthScope Plate Boundary Observatory (PBO) constructed eight new continuous GPS sites in northern Baja California, Mexico. We used our velocity model, which represents the period before the EMC earthquake, to assess postseismic velocity changes at the new PBO sites. Time series from the new PBO sites, which were constructed 4-18 months following the earthquake do not exhibit obvious exponential or logarithmic decay, showing instead fairly secular trends through the period of our analysis (2010.8-2012.5). The weighted RMS misfit to secular rates, accounting for periodic site motions is typically around 1.7 mm/yr, indicating high positioning precision and fairly linear site motion. Results of our research include new fault slip rate estimates for the greater San Andreas fault system, including model faults representing the Cerro Prieto (39.0±0.1 mm/yr), Imperial (35.7±0.1 mm/yr), and southernmost San Andreas (24.7±0.1 mm/yr), generally consistent with previous geodetic studies within the region. Velocity changes at the new PBO sites associated with the EMC earthquake are in the range 1.7±0.3 to 9.2±2.6 mm/yr. The maximum rate difference is found in Mexicali Valley, close to the rupture. Rate changes decay systematically with distance from the EMC epicenter and velocity orientations exhibit a butterfly pattern as expected from a strike slip earthquake. Sites to the south and southwest of the Baja California shear zone are moving more rapidly to the northwest relative to their motions prior to the earthquake. Sites to the west of the Laguna Salada fault zone are moving more westerly. Sites to the east of the EMC rupture move more southerly than prior to the EMC earthquake. Continued monitoring of these velocity changes will allow us to differentiate between lower crustal and upper mantle relaxation processes.

Spinler, J. C.; Bennett, R. A.

2012-12-01

9

Limnology of Laguna Tortuguero, Puerto Rico.  

National Technical Information Service (NTIS)

The principal chemical, physical and biological characteristics, as well as the hydrology of Laguna Tortuguero, Puerto Rico, were studied from 1974-75. The lagoon, with an area of 2.24 square kilometers and a volume of about 2.68 million cubic meters, con...

F. Quinones-Marquez L. A. Fuste

1978-01-01

10

Diatom paleoecology of Laguna Zoncho, Costa Rica  

Microsoft Academic Search

We analyzed diatoms in a sediment profile from Laguna Zoncho in southern Pacific Costa Rica (lake elevation 1190 m asl, depth 2.6 m, area 0.75 ha) spanning some 3240 cal  yr. Diatoms are common in the profile, which we subdivide into three zones. Zone C (~3240–1020 cal  yr B.P.) is dominated by Staurosira construens var. venter and Aulacoseira spp.; during this time, the lake was dilute

Kurt A. Haberyan; Sally P. Horn

2005-01-01

11

Molecular ecology techniques reveal both spatial and temporal variations in the diversity of archaeal communities within the athalassohaline environment of Rambla Salada, Spain.  

PubMed

We have studied the distribution of the archaeal communities in Rambla Salada (Murcia, Spain) over three different seasons and observed the influence upon them of the environmental variables, salinity, pH, oxygen and temperature. Samples were collected from three representative sites in order to gain an insight into the archaeal population of the rambla as a whole. Denaturing gradient gel electrophoresis patterns and diversity indexes indicate that the diversity of the archaeal community in Rambla Salada changed mainly according to the season. We found no significant differences between the types of sample studied: watery sediments and soils. The upwelling zone showed most diversity in its archaeal community. The overall archaeal community was composed mainly of Halobacteriales and Thermoplasmatales, accounting for 72.6 and 12.1 % of the total, respectively. Haloarcula was the most abundant genus, being present at all three sites during all three seasons. Some few Crenarchaeota were always found, mainly at low-salinity levels. Ordination canonical correspondence analysis demonstrated that salinity affected the structure of the community significantly, whilst pH, oxygen and temperature did so to a lesser extent. Most Halobacteriales correlated positively with salinity and pH, whilst Thermoplasmatales correlated negatively with both salinity and pH and positively with temperature and oxygen. The archaeal community with the highest diversity was sampled during June 2006, the season with the highest salt concentration. Catalyzed reporter deposition-fluorescence in situ hybridization showed that the percentage of archaea in Rambla Salada compared to the total number of microorganisms (as measured by DAPI) ranged from 11.1 to 16.7 %. Our research group had isolated the most abundant taxon, Haloarcula, previously in Rambla Salada using classical culture techniques, but on this occasion, using culture-independent methods, we were also able to identify some phylotypes, Halorubrum, Methanolobus, Natronomonas, Halomicrobium, Halobacterium, Halosimplex, uncultured Thermoplasmatales and uncultured Crenarchaeota, that had remained undetected during our earlier studies in this habitat. PMID:23354292

Oueriaghli, Nahid; Béjar, Victoria; Quesada, Emilia; Martínez-Checa, Fernando

2013-08-01

12

Field reconnaissance of the effects of the earthquake of April 13, 1973, near Laguna de Arenal, Costa Rica  

USGS Publications Warehouse

At about 3:34 a.m. on April 13, 1973, a moderate-sized, but widely-felt, earthquake caused extensive damage with loss of 23 lives in a rural area of about 150 km2 centered just south of Laguna de Arenal in northwestern Costa Rica (fig. 1). This report summarizes the results of the writer's reconnaissance investigation of the area that was affected by the earthquake of April 13, 1973. A 4-day field study of the meizoseismal area was carried out during the period from April 28 through May 1 under the auspices of the U.S. Geological Survey. The primary objective of this study was to evaluate geologic factors that contributed to the damage and loss of life. The earthquake was also of special interest because of the possibility that it was accompanied by surface faulting comparable to that which occurred at Managua, Nicaragua, during the disastrous earthquake of December 23, 1972 (Brown, Ward, and Plafker, 1973). Such earthquake-related surface faulting can provide scientifically valuable information on active tectonic processes at shallow depths within the Middle America arc. Also, identification of active faults in this area is of considerable practical importance because of the planned construction of a major hydroelectrical facility within the meizoseismal area by the Instituto Costarricense de Electricidad (I.C.E.). The project would involve creation of a storage reservoir within the Laguna de Arenal basin and part of the Río Arenal valley with a 75 m-high earthfill dam across Río Arenal at a point about 10 km east of the outlet of Laguna de Arenal.

Plafker, George

1973-01-01

13

Expectations for the Laguna foil implosion experiments  

SciTech Connect

Building on the results achieved in the Pioneer shot series, the Los Alamos Trailmaster project is embarking on the Laguna foil implosion experiments. In this series a Mark-IX helical generator will be coupled to an explosively formed fuse opening switch, a surface-tracking closing switch, and a vacuum power flow and load chamber. In this paper the system design will be discussed and results from zero-, one-, and two-dimensional MHD simulations will be presented. It is anticipated that the generator will provide more than 10 MA of which approx.5.5 MA will be switched to the 5-cm-radius, 2-cm-high, 250-nm-thick aluminum foil load. This should give rise to a 1 ..mu..s implosion with more than 100 kJ of kinetic energy.

Greene, A.; Brownell, J.; Caird, R.; Goforth, J.; Price, R.; Trainor, J.

1987-01-01

14

Petroleum hydrocarbons in sediments of Upper Laguna Madre  

Microsoft Academic Search

The Laguna Madre system is the largest hypersaline coastal basin in the United States. This system supports the Gulf Intracoastal Waterway (GIWW), and petroleum production wells and pipelines. Sediments from 52 Upper Laguna Madre (ULM) sites were analysed for petroleum hydrocarbons to assess the extent of contamination in the area. The resolved aliphatic hydrocarbons were C7?C21 (0.75–198 ?g g?1 dry

Virender K. Sharma; Kurtis Rhudy; Rachael Brooks; Shari Hollyfield; Felipe G. Vazquez

1997-01-01

15

Limnology of Laguna Tortuguero, Puerto Rico  

USGS Publications Warehouse

The principal chemical, physical and biological characteristics, and the hydrology of Laguna Tortuguero, Puerto Rico, were studied from 1974-75. The lagoon, with an area of 2.24 square kilometers and a volume of about 2.68 million cubic meters, contains about 5 percent of seawater. Drainage through a canal on the north side averages 0.64 cubic meters per second per day, flushing the lagoon about 7.5 times per year. Chloride and sodium are the principal ions in the water, ranging from 300 to 700 mg/liter and 150 to 400 mg/liter, respectively. Among the nutrients, nitrogen averages about 1.7 mg/liter, exceeding phosphorus in a weight ratio of 170:1. About 10 percent of the nitrogen and 40 percent of the phosphorus entering the lagoon is retained. The bottom sediments, with a volume of about 4.5 million cubic meters, average 0.8 and 0.014 percent nitrogen and phosphorus, respectively. (Woodard-USGS)

Quinones-Marquez, Ferdinand; Fuste, Luis A.

1978-01-01

16

The Characteristics of Boulby as a Site for the LAGUNA Experiment  

SciTech Connect

LAGUNA is proposed project to build in Europe a megaton-scale detector for neutrino physics, neutrino astrophysics and proton decay requiring a deep underground site. We outline here the characteristics of Boulby Mine, UK as a potential place for LAGUNA. We find that this site, already the location of several particle astrophysics experiments at 1100 m depth, has several interesting advantages for LAGUNA.

Spooner, N. J. C.; Cripps, J.; Bennett, T. [University of Sheffield, Department of Physics and Astronomy, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom)

2010-11-24

17

The Characteristics of Boulby as a Site for the LAGUNA Experiment  

NASA Astrophysics Data System (ADS)

LAGUNA is proposed project to build in Europe a megaton-scale detector for neutrino physics, neutrino astrophysics and proton decay requiring a deep underground site. We outline here the characteristics of Boulby Mine, UK as a potential place for LAGUNA. We find that this site, already the location of several particle astrophysics experiments at 1100 m depth, has several interesting advantages for LAGUNA.

Spooner, N. J. C.; Cripps, J.; Bennett, T.

2010-11-01

18

Molecular Epidemiology of Laguna Negra Virus, Mato Grosso State, Brazil  

PubMed Central

We associated Laguna Negra virus with hantavirus pulmonary syndrome in Mato Grosso State, Brazil, and a previously unidentified potential host, the Calomys callidus rodent. Genetic testing revealed homologous sequencing in specimens from 20 humans and 8 mice. Further epidemiologic studies may lead to control of HPS in Mato Grosso State.

Travassos da Rosa, Elizabeth S.; Medeiros, Daniele B.A.; Nunes, Marcio R.T.; Simith, Darlene B.; Pereira, Armando de S.; Elkhoury, Mauro R.; Santos, Elizabeth Davi; Lavocat, Marilia; Marques, Aparecido A.; Via, Alba V.G.; Kohl, Vania A.; Tercas, Ana C.P.; D`Andrea, Paulo; Bonvicino, Cibele R.; Sampaio de Lemos, Elba R.

2012-01-01

19

The Optometry Program at Universidad Autonoma de la Laguna, Mexico.  

ERIC Educational Resources Information Center

A description of the optometry program at the Universidad Autonoma de la Laguna (Mexico) provides information on the composition of the faculty, design of the five-year program as compared with the traditional four-year program, curriculum content, clinical education, visiting lecturer program, and certification of graduates. (MSE)

Gonzalez, Agustin L.

1995-01-01

20

Fault finder  

DOEpatents

A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.

Bunch, Richard H. (1614 NW. 106th St., Vancouver, WA 98665) [1614 NW. 106th St., Vancouver, WA 98665

1986-01-01

21

A geophysical and geological study of Laguna de Ayarza, a Guatemalan caldera lake  

USGS Publications Warehouse

Geologic and geophysical data from Laguna de Ayarza, a figure-8-shaped doublecaldera lake in the Guatemalan highlands, show no evidence of postcaldera eruptive tectonic activity. The bathymetry of the lake has evolved as a result of sedimentary infilling. The western caldera is steep-sided and contains a large flat-floored central basin 240 m deep. The smaller, older, eastern caldera is mostly filled by coalescing delta fans and is connected with the larger caldera by means of a deep channel. Seismicreflection data indicate that at least 170 m of flat-lying unfaulted sediments partly fill the central basin and that the strata of the pre-eruption edifice have collapsed partly along inward-dipping ring faults and partly by more chaotic collapses. These sediments have accumulated in the last 23,000 years at a minimum average sedimentation rate of 7 m/103 yr. The upper 9 m of these sediments is composed of > 50% turbidites, interbedded with laminated clayey silts containing separate diatom and ash layers. The bottom sediments have >1% organic material, an average of 4% pyrite, and abundant biogenic gas, all of which demonstrate that the bottom sediments are anoxic. Although thin (<0.5 cm) ash horizons are common, only one thick (7-16 cm) primary ash horizon could be identified in piston cores. Alterations in the mineralogy and variations in the diatom assemblage suggest magnesium-rich hydrothermal activity. ?? 1985.

Poppe, L. J.; Paull, C. K.; Newhall, C. G.; Bradbury, J. P.; Ziagos, J.

1985-01-01

22

MONITORING AND ASSESSMENT OF LAGUNA DE BAY WATERS FROM SPACE OBSERVATIONS AND OPTICAL MODELING  

Microsoft Academic Search

Laguna de Bay is one of the largest inland freshwater bodies in Asia and is currently host t o a number of industrial, aquaculture and o ther livelihood activities. Protection o f the lake from environmental degradation requires constant and reliable monitoring at synoptic scales. Time-series s atellite imagery from ASTER AM-1 sensor, were used to monitor the Laguna de

Enrico C. Paringit; Kazuo Nadaoka

23

Computational simulations of the Laguna foil implosion experiments  

SciTech Connect

Building on the results achieved in the Pioneer shot series, the Los Alamos foil implosion project is embarking on the Laguna foil implosion experiments. In this paper the system design is discussed and results from zero-, one-, and two-dimensional MHD preshot simulations are presented. The system will provide 5.5 MA to the 5-cm-radius, 2-cm-high, 250-nm-thick aluminum foil load. This should give rise to a 1.1 ..mu..s implosion with nearly 100 kJ of kinetic energy. 4 refs., 4 figs.

Greene, A.E.; Bowers, R.L.; Brownell, J.H.; Oliphant, T.A.; Peterson, D.L.; Weiss, D.L.

1988-01-01

24

Possibilities For The LAGUNA Projects At The Fréjus Site  

NASA Astrophysics Data System (ADS)

The present laboratory (LSM) at the Fréjus site and the project of a first extension of it, mainly aimed at the next generation of dark matter and double beta decay experiments, are briefly reviewed. Then the main characteristics of the LAGUNA cooperation and Design Study network are summarized. Seven underground sites in Europe are considered in LAGUNA and are under study as candidates for the installation of Megaton scale detectors using three different techniques: a liquid Argon TPC (GLACIER), a liquid scintillator detector (LENA) and a Water Cerenkov (MEMPHYS), all mainly aimed at investigation of proton decay and properties of neutrinos from SuperNovae and other astrophysical sources as well as from accelerators (Super-beams and/or Beta-beams from CERN). One of the seven sites is located at Fréjus, near the present LSM laboratory, and the results of its feasibility study are presented and discussed. Then the physics potential of a MEMPHYS detector installed in this site are emphasized both for non-accelerator and for neutrino beam based configurations. The MEMPHYNO prototype with its R&D programme is presented. Finally a possible schedule is sketched.

Mosca, Luigi

2010-11-01

25

Fault diagnosis  

NASA Technical Reports Server (NTRS)

The objective of the research in this area of fault management is to develop and implement a decision aiding concept for diagnosing faults, especially faults which are difficult for pilots to identify, and to develop methods for presenting the diagnosis information to the flight crew in a timely and comprehensible manner. The requirements for the diagnosis concept were identified by interviewing pilots, analyzing actual incident and accident cases, and examining psychology literature on how humans perform diagnosis. The diagnosis decision aiding concept developed based on those requirements takes abnormal sensor readings as input, as identified by a fault monitor. Based on these abnormal sensor readings, the diagnosis concept identifies the cause or source of the fault and all components affected by the fault. This concept was implemented for diagnosis of aircraft propulsion and hydraulic subsystems in a computer program called Draphys (Diagnostic Reasoning About Physical Systems). Draphys is unique in two important ways. First, it uses models of both functional and physical relationships in the subsystems. Using both models enables the diagnostic reasoning to identify the fault propagation as the faulted system continues to operate, and to diagnose physical damage. Draphys also reasons about behavior of the faulted system over time, to eliminate possibilities as more information becomes available, and to update the system status as more components are affected by the fault. The crew interface research is examining display issues associated with presenting diagnosis information to the flight crew. One study examined issues for presenting system status information. One lesson learned from that study was that pilots found fault situations to be more complex if they involved multiple subsystems. Another was pilots could identify the faulted systems more quickly if the system status was presented in pictorial or text format. Another study is currently under way to examine pilot mental models of the aircraft subsystems and their use in diagnosis tasks. Future research plans include piloted simulation evaluation of the diagnosis decision aiding concepts and crew interface issues. Information is given in viewgraph form.

Abbott, Kathy

1990-01-01

26

About a Gadolinium-doped Water Cherenkov LAGUNA Detector  

NASA Astrophysics Data System (ADS)

Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R&D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

Labarga, Luis

2010-11-01

27

Level-2 IPE for the Laguna Verde NPS  

SciTech Connect

In response to generic letter GL 88-20, Comision Federal de Electricidad and Instituto de Investigaciones Electricas have jointly developed the individual plant examination (IPE) for the Laguna Verde nuclear power station unit I (LVNPS). This plant is a 675-MW(electric) boiling water reactor (BWR/5) with a reinforced concrete Mark-II containment. The approach used to fulfill the IPE requirements was to make a level-1 probabilistic risk assessment (IPE level 1) plus a containment performance analysis including the behavior and release of the fission products to the environment (IPE level 2). This paper describes the level-2 portion of the LVNPS IPE, paying special attention to both some improvements to the traditional analytical methods and to the main results.

Arellano, J.; De Loera, M.A.; Rea, R. [Instituto de Investigaciones Electricas, Morelos (Mexico)

1996-12-31

28

Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA  

USGS Publications Warehouse

The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.

Mitchell, C.A.; Custer, T.W.

1986-01-01

29

Fault simulation using small fault samples  

Microsoft Academic Search

This article emphasizes simulation-based sampling techniques for estimating fault coverage that use small fault samples. Although random testing is considered to be the primary area of application of the technique it is also suitable for estimating the fault coverage of nonrandom tests based on specific fault models. Especially for fault coverages exceeding 95%, it is shown that a precise estimate

Wilfried Daehn

1991-01-01

30

Fault models  

NASA Technical Reports Server (NTRS)

A major problem in the qualification of integrated circuit cells and in the development of adequate tests for the circuits is to lack of information on the nature and density of fault models. Some of this information is being obtained from the test structures. In particular, the Pinhole Array Capacitor is providing values for the resistance of gate oxide shorts, and the Addressable Inverter Matrix is providing values for parameter distributions such as noise margins. Another CMOS fault mode, that of the open-gated transistor, is examined and the state of the transistors assessed. Preliminary results are described for a number of open-gated structures such as transistors, inverters, and NAND gates. Resistor faults are applied to various CMOS gates and the time responses are noted. The critical value for the resistive short to upset the gate response was determined.

Sayah, H. R.; Buehler, M. G.

1985-01-01

31

Lithologic controls on mineralization at the Lagunas Norte high-sulfidation epithermal gold deposit, northern Peru  

NASA Astrophysics Data System (ADS)

The 13.1-Moz high-sulfidation epithermal gold deposit of Lagunas Norte, Alto Chicama District, northern Peru, is hosted in weakly metamorphosed quartzites of the Upper Jurassic to Lower Cretaceous Chimú Formation and in overlying Miocene volcanic rocks of dacitic to rhyolitic composition. The Dafne and Josefa diatremes crosscut the quartzites and are interpreted to be sources of the pyroclastic volcanic rocks. Hydrothermal activity was centered on the diatremes and four hydrothermal stages have been defined, three of which introduced Au ± Ag mineralization. The first hydrothermal stage is restricted to the quartzites of the Chimú Formation and is characterized by silice parda, a tan-colored aggregate of quartz-auriferous pyrite-rutile ± digenite infilling fractures and faults, partially replacing silty beds and forming cement of small hydraulic breccia bodies. The ?34S values for pyrite (1.7-2.2 ‰) and digenite (2.1 ‰) indicate a magmatic source for the sulfur. The second hydrothermal stage resulted in the emplacement of diatremes and the related volcanic rocks. The Dafne diatreme features a relatively impermeable core dominated by milled slate from the Chicama Formation, whereas the Josefa diatreme only contains Chimú Formation quartzite clasts. The third hydrothermal stage introduced the bulk of the mineralization and affected the volcanic rocks, the diatremes, and the Chimú Formation. In the volcanic rocks, classic high-sulfidation epithermal alteration zonation exhibiting vuggy quartz surrounded by a quartz-alunite and a quartz-alunite-kaolinite zone is observed. Company data suggest that gold is present in solid solution or micro inclusions in pyrite. In the quartzite, the alteration is subtle and is manifested by the presence of pyrophyllite or kaolinite in the silty beds, the former resulting from relatively high silica activities in the fluid. In the quartzite, gold mineralization is hosted in a fracture network filled with coarse alunite, auriferous pyrite, and enargite. Alteration and mineralization in the breccias were controlled by permeability, which depends on the type and composition of the matrix, cement, and clast abundance. Coarse alunite from the main mineralization stage in textural equilibrium with pyrite and enargite has ?34S values of 24.8-29.4 ‰ and {?^{18 }}{{O}_{{S{{O}_4}}}} values of 6.8-13.9 ‰, consistent with H2S as the dominant sulfur species in the mostly magmatic fluid and constraining the fluid composition to low pH (0-2) and log fO2 of -28 to -30. Alunite-pyrite sulfur isotope thermometry records temperatures of 190-260 °C; the highest temperatures corresponding to samples from near the diatremes. Alunite of the third hydrothermal stage has been dated by 40Ar/39Ar at 17.0 ± 0.22 Ma. The fourth hydrothermal stage introduced only modest amounts of gold and is characterized by the presence of massive alunite-pyrite in fractures, whereas barite, drusy quartz, and native sulfur were deposited in the volcanic rocks. The {?^{18 }}{{O}_{{S{{O}_4}}}} values of stage IV alunite vary between 11.5 and 11.7 ‰ and indicate that the fluid was magmatic, an interpretation also supported by the isotopic composition of barite (?34S = 27.1 to 33.8 ‰ and {?^{18 }}{{O}_{{S{{O}_4}}}} = 8.1 to 12.7 ‰). The ?34Spy-alu isotope thermometry records temperatures of 210 to 280 °C with the highest values concentrated around the Josefa diatreme. The Lagunas Norte deposit was oxidized to a depth of about 80 m below the current surface making exploitation by heap leach methods viable.

Cerpa, Luis M.; Bissig, Thomas; Kyser, Kurt; McEwan, Craig; Macassi, Arturo; Rios, Hugo W.

2013-06-01

32

Silicic Magmas Erupted From the Laguna de Bay Caldera, Macolod Corridor, Luzon, Philippines: Geochemistry and Origin  

NASA Astrophysics Data System (ADS)

The Laguna de Bay Caldera is a depression 200 km2 in diameter that occurs within the Macolod Corridor. The Macalod corridor is a NE-SW zone of rifting through the central part of Luzon that was the site of extensive Pliestocene to Holocene volcanism, including major pyroclastic eruptions from the Laguna de Bay Caldera. This caldera has erupted large volumes of pyroclastic material, with poorly constrained published ages from < 27 ka to > 50 ka. The range in pumice sample composition in these flow units is from 53 to 69 wt. % SiO2. The abundant silicic compositions (>64 wt. % SiO2) are the focus of this investigation. Published chemical data from two nearby and relatively young, subduction related, stratavolcanoes, Taal and Makiling, show that both also contain silicic deposits. A comparison of theses silicic deposits to the silicic samples from Laguna de Bay indicate that the Laguna de Bay pyroclastic deposits contain much higher K2O/Na2O (< 1 for both Taal and Makiling and >6 for Laguna de Bay). Sr concentrations in the silicic samples from Laguna de Bay are high (> 250 ppm), which precludes large amount of plagioclase fractionation. The small Eu anomaly is consistent with this interpretation. The REE element patterns for Laguna de Bay are LREE enriched with flat HREE. No depletion occurs in the middle REE. The lack of depletion in the middle REE is in contrast to a significant concave upward pattern for the Makiling samples, an indication of amphibole in the source (no REE data are available for Taal Volcano). Our preliminary conclusions are that the silicic samples from Laguna comprise distinct compositional groups, which may be interpreted as distinct magma batches. The very high K2O/Na2O values can be used to argue against the origin of these silicic magmas by fractional crystallization or partial melting of basaltic compositions. Melting or assimilation of a more evolved source must be involved. Evolved preexisting continental crust is absent in this area. Therefore we propose that the origin of the silicic magmas from the Laguna de Bay caldera is related to melting of preexisting subduction related, evolved crust.

Flood, T. P.; Vogel, T. A.; Arpa, M. B.; Patino, L. C.; Cantane, S. G.; Arcilla, C. A.

2004-12-01

33

The Marine Ecology of the Laguna San Rafael (Southern Chile): Ice Scour and Opportunism  

NASA Astrophysics Data System (ADS)

Surveys of the intertidal fauna and flora, the plankton, fish, birds and marine mammals of the Laguna San Rafael were carried out by a Raleigh International Expedition in January-February 1993. The Laguna is dominated by the effects of scouring, low temperature and low salinity produced by the calving, tide-water San Rafael glacier that discharges into the Laguna. The fauna and flora are simple and largely limited to a small sector of the Laguna, relatively unaffected by ice. There is a predominance of herbivorous fish, ducks, geese and swans, feeding mainly on macroalgae. Penguins, cormorants, sea lions and porpoises make up the top predators. The strandline is influenced by very heavy rainfall and supports a fauna of freshwater and terrestrial molluscs and earthworms, fed upon by birds and frogs. Large numbers of mussels are present in the north-eastern sector of the Laguna, but many are found in poor condition, high on the shore. It is suggested that poor condition and mortality are caused by large calving waves that dislodge mussels. Such waves are caused by occasional loss of massive quantities of ice from the glacier.

Davenport, John

1995-07-01

34

Factors controlling navigation-channel Shoaling in Laguna Madre, Texas  

USGS Publications Warehouse

Shoaling in the Gulf Intracoastal Waterway of Laguna Madre, Tex., is caused primarily by recycling of dredged sediments. Sediment recycling, which is controlled by water depth and location with respect to the predominant wind-driven currents, is minimal where dredged material is placed on tidal flats that are either flooded infrequently or where the water is extremely shallow. In contrast, nearly all of the dredged material placed in open water >1.5 m deep is reworked and either transported back into the channel or dispersed into the surrounding lagoon. A sediment flux analysis incorporating geotechnical properties demonstrated that erosion and not postemplacement compaction caused most sediment losses from the placement areas. Comparing sediment properties in the placement areas and natural lagoon indicated that the remaining dredged material is mostly a residual of initial channel construction. Experimental containment designs (shallow subaqueous mound, submerged levee, and emergent levee) constructed in high-maintenance areas to reduce reworking did not retain large volumes of dredged material. The emergent levee provided the greatest retention potential approximately 2 years after construction.

Morton, R. A.; Nava, R. C.; Arhelger, M.

2001-01-01

35

Computational simulations of the Laguna foil implosion experiments  

SciTech Connect

The Los Alamos foil implosion project is intended to produce a source of intense laboratory x-radiation for physics and fusion studies. Following the Pioneer shot series, the project is now embarking on the Laguna foil implosion experiments. In this series a Mark-IX helical generator will be coupled to an explosively-formed-fuse opening switch, a surface discharge closing switch, and a vacuum power flow and load chamber. The system design will be discussed and an overview of zero-, one-, and two-dimensional MHD preshot simulations will be presented. The generator should provide more than 11 MA of which /approximately/5.5 MA will be switched to the 5-cm- radius, 2-cm-high, 250-nm-thick aluminum foil load. This should give rise to a 1.1 ..mu..s implosion with tens of kilojoules of kinetic energy. Zero-dimensional calculations serve to optimize the pulse- power system. One-dimensional, Lagrangian, MHD calculations are made to estimate temperature, densities and radiation output. The temperature and density profiles predicted by the 1-D code are used as initial conditions for our 2-D Eulerian code. The 2-D calculations predict a small amount of radiated energy from a decoupled plasma associated with Rayleigh-Taylor bubbles. This matter is predicted to have electron and ion temperatures in the keV regime as the bubble material thermalizes ahead of the bulk of the plasma.

Greene, A.E.; Bowers, R.L.; Brownell, J.H.; Oliplant, T.A.; Peterson, D.L.; Weiss, D.L.

1989-01-01

36

High-Performance Wireless Internet Connection to Mount Laguna Observatory  

NASA Astrophysics Data System (ADS)

A 45 Mbit/sec full-duplex wireless Internet backbone is now under construction that will connect SDSU's Mount Laguna Observatory (MLO) to the San Diego Supercomputer Center (SDSC), which is located on the campus of UCSD. The SDSU campus is connected to the SDSC via Abilene/OC3 (Internet2) at 155 Mbit/sec. The MLO-SDSC backbone is part of the High-Performance Wireless Research and Education Network (HPWREN) project. Other scientific applications include earthquake monitoring from a remote array of automated seismic stations operated by researchers at the UCSD Institute for Geophysics and Planetary Physics, and environmental monitoring at Ecology field stations administered by SDSU. Educational initiatives include bringing the Internet to schools and educational centers at remote Indian reservations such as Pala and Rincon. HPWREN will allow SDSU astronomers and their collaborators to transmit CCD images to their home institutions while observations are being made. Archive retrieval of images from on-campus data bases, for comparison purposes, could easily be done. SDSU desires to build a modern, large telescope at MLO. HPWREN would support both robotic and remote observing capabilities for such a telescope. Astronomers could observe at their home institutions with multiple workstations to feed command and control instructions, data, and slow-scan video, which would give them the "feel" of being in a control room next to the telescope. HPWREN was funded by the NSF under grant ANI-0087344.

Etzel, P. B.; Braun, H.-W.

2000-12-01

37

CMOS Bridging Fault Detection  

Microsoft Academic Search

The authors compare the performance of two test generation techniques, stuck fault testing and current testing, when applied to CMOS bridging faults. Accurate simulation of such faults mandated the development of several new design automation tools, including an analog-digital fault simulator. The results of this simulation are analyzed. It is shown that stuck fault test generation, while inherently incapable of

Thomas M. Storey; Wojciech Maly

1990-01-01

38

Normal Fault Visualization  

NSDL National Science Digital Library

This module demonstrates the motion on an active normal fault. Faulting offsets three horizontal strata. At the end of the faulting event, surface topography has been generated. The upper rock layer is eroded by clicking on the 'begin erosion' button. The operator can manipulate the faulting motion, stopping and reversing motion on the fault at any point along the transit of faulting. The action of erosion is also interactive. One possible activity is an investigation of the control of different faulting styles on regional landscape form. This visual lends itself to an investigation of fault motion, and a comparison of types of faults. The interactive normal faulting visual could be compared to other interactive visuals depicting thrust faults, reverse faults, and strike slip faults (interactive animations of these fault types can be found by clicking on 'Media Types' at top red bar, then 'Animations', then 'Faults'). By comparing the interactive images of different types of faulting with maps of terrains dominated by different faulting styles, students are aided in conceptualizing how certain faulting styles produce distinctive landforms on the earth's surface (e.g., ridge and valley topography [thrust faulting dominant] versus basin-and-range topography [normal faulting dominant]). Jimm Myers, geology professor at the University of Wyoming, originated the concept of The Magma Foundry, a website dedicated to improving Earth science education across the grade levels. The Magma Foundry designs and creates modular, stand-alone media components that can be utilized in a variety of pedagogical functions in courses and labs.

Myers, Jimm

39

The radiological emergency plan to the Laguna Verde Nuclear Power Plant  

Microsoft Academic Search

In this paper, it is described the main characteristics of the area surrounding the Laguna Verde Nuclear Power Plant, in terms of population, main economic activities, housing and infrastructure. Based on those factors, the most important features of the Radiological Emergency Plan are described.

M. M. Villard; R. O. Magana

1992-01-01

40

A NEW STRAIN OF PARATETRAMITUS JUGOSUS FROM LAGUNA FIGUEROA, BAJA CALIFORNIA, MEXICO  

Microsoft Academic Search

A euryhalic, moderately temperature tolerant, fast growing strain of the amoe bomastigot& Paratetramitus jugosus was isolated from the North Pond flat lami nated microbial mat at Laguna Figueroa, Baja California del Norte, Mexico. The morphology was studied with phase contrast, differential interference contrast, scan ning, and transmission electron microscopy. On the basis of its life cycle charac teristics, growth rate,

LAURIE K. READ; LYNN MARGULIS; JOHN STOLZ; ROBERT OBAR; THOMAS K. SAWYER

41

Fault architecture, fault rocks and fault rock properties in carbonate rocks  

Microsoft Academic Search

Fault architecture, fault rocks and fault rock properties in carbonate rocks The current study addresses a comparative analysis of fault zones in limestone and dolomite rocks comparing the architecture of fault core and damage zones, fault rocks, and the hydrodynamic properties of faults exposed in the Upper Triassic Wetterstein Fm. of the Hochschwab Massif (Austria). All analysed faults are sinistral

Helene Bauer; Kurt Decker

2010-01-01

42

Design of fault simulator  

Microsoft Academic Search

Fault simulator is proposed to understand and evaluate all possible fault propagation scenarios, which is an essential part of safety design and operation design and support of chemical\\/production processes. Process models are constructed and integrated with fault models, which are formulated in qualitative manner using fault semantic networks (FSN). Trend analysis techniques are used to map real time and simulation

Hossam A. Gabbar; Hanaa E. Sayed; Ajiboye S. Osunleke; Hara Masanobu

2009-01-01

43

On Distributed Fault Simulation  

Microsoft Academic Search

The authors examine the computational aspects of fault simulation of digital circuits and address issues related to the efficient partitioning of a fault simulation task to a number of subtasks assignable for execution to the nodes of a distributed system. They review the basic concepts involved in the operation of fault simulation. They describe the implementation of a distributed fault

Tassos Markas; Mark Royals; Nick Kanopoulos

1990-01-01

44

High impedance fault detection  

US Patent & Trademark Office Database

An apparatus, system, and method for detecting high impedance faults in electrical power lines using a composite high impedance fault detection system having a voter logic that samples the logical outputs from a plurality of independent high impedance detection systems and determines a high impedance fault if any two of the plurality of independent high impedance detection systems indicates a high impedance fault. Preferably, the plurality of high impedance detection systems include a wavelet based high impedance fault detection system having a first logical output, a higher order statistics based high impedance fault detection system having a second logical output, and a neural net based high impedance fault detection system having a third logical output. Preferably, each of the plurality of high impedance fault detection systems includes an independent high impedance fault detection application that independently detects a high impedance fault on the electrical power line.

2006-06-27

45

Fault analysis based on fault reporting in JSP software development  

Microsoft Academic Search

A fault analysis procedure is proposed for software development using JSP (Jackson structured programming). In the procedure, it is assumed that developers submit a fault report, which includes information (such as fault type, cause of fault and product) on actual fault correction activities. The procedure can identify the step in the JSP process at which fault might be introduced. Fault

Yukio MOHRI; T. Kikuno

1991-01-01

46

Behavioral Fault Simulation in VHDL  

Microsoft Academic Search

This paper presents two tools which facilitate the fault simulation of behavioral models described using VHDL. The first tool is the Behavioral Fault Mapper (BFM). The BFM algorithm accepts a fault-free VHDL model and a fault list of N faults from which it produces N faulty models. The process of mapping the faults in the fault list onto copies of

P. C. Ward; James R. Armstrong

1990-01-01

47

The microbial community at Laguna Figueroa, Baja California Mexico - From miles to microns  

NASA Technical Reports Server (NTRS)

The changes in the composition of the stratified microbial community in the sediments at Laguna Figeroa following floods are studied. The laguna which is located on the Pacific coast of the Baja California peninsula 200 km south of the Mexican-U.S. border is comprised of an evaporite flat and a salt marsh. Data collected from 1979-1983 using Landsat imagery, Skylab photographs, and light and transmission electron microscopy are presented. The flood conditions, which included 1-3 m of meteoric water covering the area and a remanent of 5-10 cm of siliciclastic and clay sediment, are described. The composition of the community prior to the flooding consisted of Microcoleus, Phormidium sp., a coccoid cynanobacteria, Phloroflexus, Ectothiorhodospira, Chloroflexus, Thiocapsa sp., and Chromatium. Following the floods Thiocapsa, Chromatium, Oscillatora sp., Spirulina sp., and Microcoleus are observed in the sediments.

Stolz, J. F.

1985-01-01

48

Different Strategies to Develop Distributed Object Systems at University of La Laguna  

Microsoft Academic Search

The use of Java Remote Method Invocation and Java Servlets allow the development of distributed systems. The University of La Laguna is made up of sixty departments on three separate\\u000a sites. There are some 30,000 people involved in its day-to-day organisation, including students, teaching staff and service\\u000a and administrative personnel. The geographical distribution of the University is a problem as

Antonio Estévez; F. H. Priano; M. Pérez; Jesus A. González; Daniel González-morales; José L. Roda

2000-01-01

49

Waterbirds (other than Laridae) nesting in the middle section of Laguna Cuyutlán, Colima, México.  

PubMed

Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus), Tricolored Egret (Egretta tricolor), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Great Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Black-crowned Night-heron (Nycticorax nycticorax), Yellow-crowned Night-heron (Nyctanassa violacea), Green Heron (Butorides virescens), Roseate Spoonbill (Platalea ajaja), White Ibis (Eudocimus albus), Black-bellied Whistling-duck (Dendrocygna autumnalis), Clapper Rail (Rallus longirostris), Snowy Plover (Charadrius alexandrinus), and Black-necked Stilt (Himantopus mexicanus). These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla), Royal Terns (Thalasseus maximus), Gull-billed Terns (Gelochelidon nilotica), Forster's Terns (S. forsteri), Least Terns (Sternula antillarum), and Black Skimmer (Rynchops niger), and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status. PMID:18624252

Mellink, Eric; Riojas-López, Mónica E

2008-03-01

50

Hydrocarbon concentrations in sediments and clams (Rangia cuneata) in Laguna de Pom, Mexico  

SciTech Connect

Laguna de Pom is a coastal lagoon within the Laguna de Terminos system in southern Gulf of Mexico. It belongs to the Grijalva-Usumacinta basin, and is located between 18{degrees} 33{prime} and 18{degrees} 38{prime} north latitude and 92{degrees} 01{prime} and 92{degrees} 14{prime} west longitude, in the Coastal Plain physiographic Province of the Gulf. It is ellipsoidal and approximately 10 km long, with a surface area of 5,200 ha and a mean depth of 1.5 m. Water salinity and temperature ranges are 0 to 13 {per_thousand} and 25{degrees} to 31{degrees}C, respectively. Benthic macrofauna is dominated by bivalves such as the clams Rangia cuneata, R. flexuosa, and Polymesoda carolineana. These clams provide the basis of an artisanal fishery, which is the main economic activity in the region. The presence of several oil-processing facilities around the lagoon is very conspicuous, which together with decreasing yields has created social conflicts, with the fishermen blaming the mexican state oil company (PEMEX) for the decrease in the clam population. This work aims to determine if the concentration of hydrocarbons in the clams (R. cuneata) and sediments of Laguna de Pom are responsible for the declining clam fishery. 11 refs., 4 figs., 2 tabs.

Alvarez-Legorreta, T.; Gold-Bouchot, G.; Zapata-Perez, O. [Unidad Merida (Mexico)

1994-01-01

51

Fault Tolerant Strategies for BLDC Motor Drives under Switch Faults  

Microsoft Academic Search

In this paper, the fault tolerant system for BLDC motors has been proposed to maintain the control performance under switching device faults of inverter. The proposed fault tolerant system provides compensation for open-circuit faults and short-circuit faults in power converter. The fault identification is quickly achieved by simple algorithm using the characteristic of BLDC motor drives. The drive system after

Byoung-Gun Park; Tae-Sung Kim; Ji-Su Ryu; Dong-Seok Hyun

2006-01-01

52

Bridge fault diagnosis using stuck-at fault simulation  

Microsoft Academic Search

A new diagnostic fault simulator is described that diagnoses both feedback and nonfeedback bridge faults in combinational circuits while using information from fault simulation of single stuck-at faults. A realistic fault model is used which considers the existence of the Byzantine Generals problem. Sets representing nodes possibly involved in a defect are partitioned based on logic and fault simulation of

Jue Wu; Elizabeth M. Rudnick

2000-01-01

53

Fault Mapping in Haiti  

USGS Multimedia Gallery

USGS geologist Carol Prentice surveying features that have been displaced by young movements on the Enriquillo fault in southwest Haiti.  The January 2010 Haiti earthquake was associated with the Enriquillo fault....

2010-08-13

54

Nonlinear Fault Diagnosis.  

National Technical Information Service (NTIS)

A summary of several research projects in the nonlinear fault diagnosis is given. Several alternative algorithms for the solution of the nonlinear fault diagnosis problem are presented, together with a diagnosibility theory, and a set of criteria which an...

R. W. Liu K. Nakajima P. Olivier Q. D. Ngo R. Saeks

1981-01-01

55

Fault recovery characteristics of the fault tolerant multi-processor  

NASA Technical Reports Server (NTRS)

The fault handling performance of the fault tolerant multiprocessor (FTMP) was investigated. Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles byzantine or lying faults. It is pointed out that these weak areas in the FTMP's design increase the probability that, for any hardware fault, a good LRU (line replaceable unit) is mistakenly disabled by the fault management software. It is concluded that fault injection can help detect and analyze the behavior of a system in the ultra-reliable regime. Although fault injection testing cannot be exhaustive, it has been demonstrated that it provides a unique capability to unmask problems and to characterize the behavior of a fault-tolerant system.

Padilla, Peter A.

1990-01-01

56

The San Andreas Fault  

USGS Publications Warehouse

The presence of the San Andreas fault was brought dramatically to world attention on April 18, 1906, when sudden displacement along the fault produced the great San Francisco earthquake and fire. This earthquake, however, was but one of many that have resulted from episodic displacement along the fault throughout its life of about 15-20 million years.

Schulz, Sandra S.; Wallace, Robert E.

1993-01-01

57

Diagnosing CMOS bridging faults with stuck-at fault dictionaries  

Microsoft Academic Search

It is shown that the traditional approach to diagnosing stuck-at faults with fault dictionaries generated for stuck-at faults is not appropriate for diagnosing CMOS bridging faults. A novel technique for using stuck-at-fault dictionaries to diagnose bridging faults is described. Teradyne's LASAR was used to simulate bridging and stuck-at faults in a number of combinational circuits, including parity trees, multiplexers, and

Steven D. Millman; Edward J. McCluskey; John M. Acken

1990-01-01

58

Rough faults, distributed weakening, and off-fault deformation  

Microsoft Academic Search

We report systematic spatial variations in fault rocks along nonplanar strike-slip faults cross-cutting the Lake Edison Granodiorite, Sierra Nevada, California (Sierran wavy fault) and Lobbia outcrops of the Adamello Batholith in the Italian Alps (Lobbia wavy fault). In the case of the Sierran fault, pseudotachylyte formed at contractional fault bends, where it is found as thin (1–2 mm) fault-parallel veins.

W. Ashley Griffith; Stefan Nielsen; Giulio Di Toro; Steven A. F. Smith

2010-01-01

59

Patagonian and Antarctic dust as recorded in the sediments of Laguna Potrok Aike (Patagonia, Argentina)  

NASA Astrophysics Data System (ADS)

Although an increasing number of terrestrial paleoclimatic records from southern South America has been published during the last decade, these archives mostly cover the Lateglacial and/or the Holocene. Only little is known about the Patagonian climate before the Last Glacial Maximum. Here, we present a continuous, high-resolution magnetic susceptibility record for the past 48 ka from the maar lake Laguna Potrok Aike (51°58' S, 70°23' W, southern Patagonia, Argentina). Magnetic susceptibility serves as an excellent parameter for the parallelization of sediment cores all over Laguna Potrok Aike including sediment cores taken within the ICDP (International Continental Scientific Drilling Program) project PASADO (Potrok Aike maar lake Sediment Archive Drilling prOject). Additionally, magnetic susceptibility is assumed to be a proxy for dust deposition in this lake. Distinct similarities were found between the independently dated magnetic susceptibility record from Laguna Potrok Aike and the non-sea-salt calcium (nss-Ca) flux from the EPICA Dome C ice core record (75°06'S, 123°24'E) the latter being a proxy for mineral dust deposition in Antarctica [1]. Comparison of the two records and variations in grain size of the Laguna Potrok Aike sediment records indicate a relatively high aeolian activity in southern South America during the glacial period. During the Holocene climatic conditions driving sediment deposition seem to have been more variable and less dominated by wind compared to glacial times. Although the source of the dust found in Antarctic ice cores often has been attributed to Patagonia [2], we present the first evidence for contemporaneity of aeolian deposition in both the target area (Antarctica) and the major source area (Patagonia). Considering the similarities of the two records, magnetic susceptibility might yield the potential for chronological information: transfer of the ice core age model to a lacustrine sediment record. This would be important as additional time control for the recently recovered sediment record within the ICDP deep drilling project PASADO. To support this idea, we performed Sr/Nd-isotopic analyses on the assumed aeolian, well sorted fraction (63-200 µm) deposited in Laguna Potrok Aike during the last glaciation as well as on the <5 µm fraction which is commonly found as dust in Antarctica - both on the same samples. These results are compared to the Sr/Nd-isotopic signatures measured directly on dust from Antarctic ice cores [2]: the isotopic data field of sediments from Laguna Potrok Aike superposes a large part of isotopic data from Antarctic dust, although the 87Sr/86Sr-data seems to show a slight offset to lower values. In conclusion our analyses confirm previous studies that suggested southern South America to be the main source area of east Antarctic dust during glacial periods. However, this is the first evidence for a contemporaneous dust deposition pattern in Patagonia and Antarctica. References [1] R. Röthlisberger, R. Mulvaney, E.W. Wolff, M.A. Hutterli, M. Bigler, S. Sommer, J. Jouzel, Dust and sea salt variability in central East Antarctica (Dome C) over the last 45 kyrs and its implications for southern high-latitude climate, Geophysical Research Letters 29 (2002) doi:10.1029/2002GL015186. [2] B. Delmonte, I. Basile-Doelsch, J.R. Petit, V. Maggi, M. Revel-Rolland, A. Michard, E. Jagoutz, F. Grousset, Comparing the Epica and Vostok dust records during the last 220,000 years: stratigraphical correlation and provenance in glacial periods, Earth-Science Reviews 66 (2004) 63-87.

Haberzettl, Torsten; Stopp, Annemarie; Lisé-Pronovost, Agathe; Gebhardt, Catalina; Ohlendorf, Christian; Zolitschka, Bernd; von Eynatten, Hilmar; Kleinhanns, Ilka; Pasado Science Team

2010-05-01

60

Accelerated Fault Simulation and Fault Grading in Combinational Circuits  

Microsoft Academic Search

The principles of fault simulation and fault grading are introduced by a general description of the problem. Based upon the well-known concept of restricting fault simulation to the fanout stems and of combining it with a backward traversal inside the fanout-free regions of the circuit, proposals are presented to further accelerate fault simulation and fault grading. These proposals aim at

Kurt Antreich; Michael H. Schulz

1987-01-01

61

On the Emulation of Software Faults by Software Fault Injection  

Microsoft Academic Search

This paper presents an experimental study on the emulation of software faults by fault injection. In a first experiment, a set of real software faults has been compared with faults injected by a SWIFI tool (Xception) to evaluate the accuracy of the injected faults. Results revealed the limitations of Xception (and other SWIFI tools) in the emulation of different classes

Henrique Madeira; Diamantino Costa; Marco Vieira

2000-01-01

62

Rock Magnetic Properties of Laguna Carmen (Tierra del Fuego, Argentina): Implications for Paleomagnetic Reconstruction  

NASA Astrophysics Data System (ADS)

We report preliminary results obtained from a multi-proxy analysis including paleomagnetic and rock-magnetic studies of two sediment cores of Laguna Carmen (53°40'60" S 68°19'0" W, ~83m asl) in the semiarid steppe in northern Tierra del Fuego island, Southernmost Patagonia, Argentina. Two short cores (115 cm) were sampled using a Livingstone piston corer during the 2011 southern fall. Sediments are massive green clays (115 to 70 cm depth) with irregularly spaced thin sandy strata and lens. Massive yellow clay with thin sandy strata continues up to 30 cm depth; from here up to 10 cm yellow massive clays domain. The topmost 10 cm are mixed yellow and green clays with fine sand. Measurements of intensity and directions of Natural Remanent Magnetization (NRM), magnetic susceptibility, isothermal remanent magnetization, saturation isothermal remanent magnetization (SIRM), back field and anhysteretic remanent magnetization at 100 mT (ARM100mT) were performed and several associated parameters calculated (ARM100mT/k and SIRM/ ARM100mT). Also, as a first estimate of relative magnetic grain-size variations, the median destructive field of the NRM (MDFNRM), was determined. Additionally, we present results of magnetic parameters measured with vibrating sample magnetometer (VSM). The stability of the NRM was analyzed by alternating field demagnetization. The magnetic properties have shown variable values, showing changes in both grain size and concentration of magnetic minerals. It was found that the main carrier of remanence is magnetite with the presence of hematite in very low percentages. This is the first paleomagnetic study performed in lakes located in the northern, semiarid fuegian steppe, where humid-dry cycles have been interpreted all along the Holocene from an aeolian paleosoil sequence (Orgeira et el, 2012). Comparison between paleomagnetic records of Laguna Carmen and results obtained in earlier studies carried out at Laguna Potrok Aike (Gogorza et al., 2012) were performed. References Gogorza, C.S.G., Irurzun, M.A., Sinito, A.M., Lisé-Pronovost, A., St-Onge, G., Haberzettl, T., Ohlendorf, C., Kastner, S., Zolitschka, B., 2012. High-resolution paleomagnetic records from Laguna Potrok Aike (Patagonia, Argentina) for the last 16,000 years. Geochemistry Geophysics Geosystems. 13, Q12Z37. Orgeira, M.J., Vásquez, C.A., Coronato, A., Ponce, F., Moreto, A., Osterrieth, M, Egli, R., Onorato, R., 2012. Magnetic properties of Holocene edaphized silty eolian sediments from Tierra del Fuego (Argentina). Revista de la Sociedad Geológica de España. 25 (1-2), 45-56.

Gogorza, C. G.; Orgeira, M. J.; Ponce, F.; Fernández, M.; Laprida, C.; Coronato, A.

2013-05-01

63

Niebla ceruchis from Laguna Figueroa: dimorphic spore morphology and secondary compounds localized in pycnidia and apothecia.  

PubMed

During and after the floods of 1979-80 Niebla ceruchis growing epiphytically on Lycium brevipes was one of the dominant aspects of the vegetation in the coastal dunal complex bordering the microbial mats at Laguna Figueroa, Baja California Norte, Mexico. The lichen on denuded branches of Lycium was far more extensively distributed than Lycium lacking lichen. Unusual traits of this Niebla ceruchis strain, namely localization of lichen compounds in the mycobiont reproductive structures (pycnidia and apothecia) and simultaneous presence of bilocular and quadrilocular ascospores, are reported. The abundance of this coastal lichen cover at the microbial mat site has persisted through April 1988. PMID:11542138

Enzien, M; Margulis, L

1988-01-01

64

Niebla ceruchis from Laguna Figueroa: dimorphic spore morphology and secondary compounds localized in pycnidia and apothecia  

NASA Technical Reports Server (NTRS)

During and after the floods of 1979-80 Niebla ceruchis growing epiphytically on Lycium brevipes was one of the dominant aspects of the vegetation in the coastal dunal complex bordering the microbial mats at Laguna Figueroa, Baja California Norte, Mexico. The lichen on denuded branches of Lycium was far more extensively distributed than Lycium lacking lichen. Unusual traits of this Niebla ceruchis strain, namely localization of lichen compounds in the mycobiont reproductive structures (pycnidia and apothecia) and simultaneous presence of bilocular and quadrilocular ascospores, are reported. The abundance of this coastal lichen cover at the microbial mat site has persisted through April 1988.

Enzien, M.; Margulis, L.

1988-01-01

65

It's Not Your Fault  

NSDL National Science Digital Library

In this lesson students will learn about tectonic plate movement. They will discover that we can measure the relative motions of the Pacific Plate and the North American Plate along the San Andreas Fault. Students will be able to compare and contrast movements on either side of the San Andreas Fault, calculate the amount of movement of a tectonic plate over a period of time, and describe the processes involved in the occurrence of earthquakes along the fault.

66

How Faults Shape the Earth.  

ERIC Educational Resources Information Center

Presents fault activity with an emphasis on earthquakes and changes in continent shapes. Identifies three types of fault movement: normal, reverse, and strike faults. Discusses the seismic gap theory, plate tectonics, and the principle of superposition. Vignettes portray fault movement, and the locations of the San Andreas fault and epicenters of…

Bykerk-Kauffman, Ann

1992-01-01

67

Analysis of fault traps  

SciTech Connect

Unfaulted four-way-dip closures are the simplest and most attractive hydrocarbon traps. A single sealing lithology can provide both top and lateral seals. Seal risks are minimized with unfaulted four-way-dip closures. Unfortunately, most large four-way-drip closures have already been drilled, particularly in mature areas such as the US Gulf Coast. Exceptions may exist in deep water, at great depth, or in areas with significant lateral velocity variations, but for the most part, explorationists working mature areas are looking for either fault traps or stratigraphic traps. This article focuses on extensional fault systems, although many of the observations are applicable to compressional and strike-slip faulting. The following topics are discussed: mapping faults including discussions on the aliasing problem, fault shape, 3-D data, en echelon faults and the coherence cube; a general discussion of fault traps; juxtaposition traps and the use of ``Allan sections;`` and fault-sealing traps and the three mechanisms that cause fault-zone capillary properties to differ from unfaulted rock -- clay smear, grain crushing and diagenesis.

Brenneke, J.C. [Subsurface Consultants and Associates, Inc., Houston, TX (United States)

1995-12-01

68

Water-quality reconnaissance of Laguna Tortuguero, Vega Baja, Puerto Rico, March 1999-May 2000  

USGS Publications Warehouse

The Laguna Tortuguero, a slightly saline to freshwater lagoon in north-central Puerto Rico, has a surface area of about 220 hectares and a mean depth of about 1.2 meters. As part of a water-quality reconnaissance, water samples were collected at about monthly and near bi-monthly intervals from March 1999 to May 2000 at four sites: three stations inside the lagoon and one station at the artificial outlet channel dredged in 1940, which connects the lagoon with the Atlantic Ocean. Physical characteristics that were determined from these water samples were pH, temperature, specific conductance, dissolved oxygen, dissolved oxygen saturation, and discharge at the outlet canal. Other water-quality constituents also were determined, including nitrogen and phosphorus species, organic carbon, chlorophyll a and b, plankton biomass, hardness, alkalinity as calcium carbonate, and major ions. Additionally, a diel study was conducted at three stations in the lagoon to obtain data on the diurnal variation of temperature, specific conductance, dissolved oxygen, and dissolved oxygen saturation. The data analysis indicates the water quality of Laguna Tortuguero complies with the Puerto Rico Environmental Quality Board standards and regulations.

Soler-Lopez, Luis; Guzman-Rios, Senen; Conde-Costas, Carlos

2006-01-01

69

Spatial distribution of Late Holocene sediment infill controlled by lake internal depositional dynamics, Laguna Potrok Aike (southern Patagonia, Argentina)  

Microsoft Academic Search

The maar Laguna Potrok Aike (51°S, 70°W) is situated in the dry steppe environment of southern Patagonia. This 100 m deep lake is a palaeolimnological key site among the emerging terrestrial climate archives of the southern hemisphere and therefore was chosen as an ICDP drilling site. Interdisciplinary multi-proxy sediment studies document the sensitivity of this lacustrine record to palaeoclimatic and

Stephanie Kastner; Christian Ohlendorf; Torsten Haberzettl; Andreas Lücke; Nora I. Maidana; Christoph Mayr; Frank Schäbitz; Bernd Zolitschka

2010-01-01

70

Denali Fault: Susitna Glacier  

USGS Multimedia Gallery

Helicopters and satellite phones were integral to the geologic field response. Here, Peter Haeussler is calling a seismologist to pass along the discovery of the Susitna Glacier thrust fault. View is to the north up the Susitna Glacier. The Denali fault trace lies in the background where the two lan...

2008-12-15

71

Folds and Faults  

NSDL National Science Digital Library

In this activity, students will learn how rock layers are folded and faulted and how to represent these structures in maps and cross sections. They will use playdough to represent layers of rock and make cuts in varying orientations to represent faults and other structures.

72

Fault tree handbook  

Microsoft Academic Search

This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic

D. F. Haasl; N. H. Roberts; W. E. Vesely; F. F. Goldberg

1981-01-01

73

Fault rocks lab  

NSDL National Science Digital Library

This lab is intended to give students some hands on experience looking at fault rocks with a suite of cataclasites and mylonites I have collected. The focus is on identifying key textural features in both hand sample and thin section and understanding how deformation within a fault zone varies with depth.

Singleton, John

74

SFT: scalable fault tolerance  

Microsoft Academic Search

In this paper we will present a new technology that we are currently developing within the SFT: Scalable Fault Tolerance FastOS project which seeks to implement fault tolerance at the operating system level. Major design goals include dynamic reallocation of resources to allow continuing execution in the presence of hardware failures, very high scalability, high efficiency (low overhead), and transparency---requiring

Fabrizio Petrini; Jarek Nieplocha; Vinod Tipparaju

2006-01-01

75

Solar system fault detection  

DOEpatents

A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

Farrington, Robert B. (Wheatridge, CO); Pruett, Jr., James C. (Lakewood, CO)

1986-01-01

76

Origin and evolution of the Laguna Potrok Aike maar (Patagonia, Argentina)  

NASA Astrophysics Data System (ADS)

Laguna Potrok Aike, a maar lake in southern-most Patagonia, is located at about 110 m a.s.l. in the Pliocene to late Quaternary Pali Aike Volcanic Field (Santa Cruz, southern Patagonia, Argentina) at about 52°S and 70°W, some 20 km north of the Strait of Magellan and approximately 90 km west of the city of Rio Gallegos. The lake is almost circular and bowl-shaped with a 100 m deep, flat plain in its central part and an approximate diameter of 3.5 km. Steep slopes separate the central plain from the lake shoulder at about 35 m water depth. At present, strong winds permanently mix the entire water column. The closed lake basin contains a sub saline water body and has only episodic inflows with the most important episodic tributary situated on the western shore. Discharge is restricted to major snowmelt events. Laguna Potrok Aike is presently located at the boundary between the Southern Hemispheric Westerlies and the Antarctic Polar Front. The sedimentary regime is thus influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Previous studies demonstrated that closed lakes in southern South America are sensitive to variations in the evaporation/precipitation ratio and have experienced drastic lake level changes in the past causing for example the desiccation of the 75 m deep Lago Cardiel during the Late Glacial. Multiproxy environmental reconstruction of the last 16 ka documents that Laguna Potrok Aike is highly sensitive to climate change. Based on an Ar/Ar age determination, the phreatomagmatic tephra that is assumed to relate to the Potrok Aike maar eruption was formed around 770 ka. Thus Laguna Potrok Aike sediments contain almost 0.8 million years of climate history spanning several past glacial-interglacial cycles making it a unique archive for non-tropical and non-polar regions of the Southern Hemisphere. In particular, variations of the hydrological cycle, changes in eolian dust deposition, frequencies and consequences of volcanic activities and other natural forces controlling climatic and environmental responses can be tracked throughout time. Laguna Potrok Aike has thus become a major focus of the International Continental Scientific Drilling Program. Drilling operations were carried out within PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Project) in late 2008 and penetrated ~100 m into the lacustrine sediment. Laguna Potrok Aike is surrounded by a series of subaerial paleo-shorelines of modern to Holocene age that reach up to 21 m above the 2003 AD lake level. An erosional unconformity which can be observed basin-wide along the lake shoulder at about 33 m below the 2003 AD lake level marks the lowest lake level reached during Late Glacial to Holocene times. A high-resolution seismic survey revealed a series of buried, subaquatic paleo-shorelines that hold a record of the complex transgressional history of the past approximately 6800 years, which was temporarily interrupted by two regressional phases from approximately 5800 to 5400 and 4700 to 4000 cal BP. Seismic reflection and refraction data provide insights into the sedimentary infill and the underlying volcanic structure of Laguna Potrok Aike. Reflection data show undisturbed, stratified lacustrine sediments at least in the upper ~100 m of the sedimentary infill. Two stratigraphic boundaries were identified in the seismic profiles (separating subunits I-ab, I-c and I-d) that are likely related to changes in lake level. Subunits I-ab and I-d are quite similar even though velocities are enhanced in subunit I-d. This might point at cementation in subunit I-d. Subunit I-c is restricted to the central parts of the lake and thins out laterally. A velocity-depth model calculated from seismic refraction data reveals a funnel-shaped structure embedded in the sandstone rocks of the surrounding Santa Cruz Formation. This funnel structure is filled by lacustrine sediments of up to 370 m in thickness. These can be separated into two

Gebhardt, A. C.; de Batist, M.; Niessen, F.; Anselmetti, F. S.; Ariztegui, D.; Ohlendorf, C.; Zolitschka, B.

2009-04-01

77

Characterization of Fault Zones  

NASA Astrophysics Data System (ADS)

- There are currently three major competing views on the essential geometrical, mechanical, and mathematical nature of faults. The standard view is that faults are (possibly segmented and heterogeneous) Euclidean zones in a continuum solid. The continuum-Euclidean view is supported by seismic, gravity, and electromagnetic imaging studies; by successful modeling of observed seismic radiation, geodetic data, and changes in seismicity patterns; by detailed field studies of earthquake rupture zones and exhumed faults; and by recent high resolution hypocenter distributions along several faults. The second view focuses on granular aspects of fault structures and deformation fields. The granular view is supported by observations of rock particles in fault zone gouge; by studies of block rotations and the mosaic structure of the lithosphere (which includes the overall geometry of plate tectonics); by concentration of deformation signals along block boundaries; by correlation of seismicity patterns on scales several times larger than those compatible with a continuum framework; and by strongly heterogeneous wave propagation effects on the earth's surface. The third view is that faults are fractal objects with rough surfaces and branching geometry. The fractal view is supported by some statistical analysis of regional hypocenter locations; by long-range correlation of various measurements in geophysical boreholes; by the fact that observed power-law statistics of earthquakes are compatible with an underlying scale-invariant geometrical structure; by geometrical analysis of fault traces at the earth's surface; and by measurements of joint and fault surfaces topography.There are several overlaps between expected phenomenology in continuum-Euclidean, granular, and fractal frameworks of crustal deformation. As examples, highly heterogeneous seismic wavefields can be generated by granular media, by fractal structures, and by ground motion amplification around and scattering from an ensemble of Euclidean fault zones. A hierarchical granular structure may have fractal geometry. Power-law statistics of earthquakes can be generated by slip on one or more heterogeneous planar faults, by a fractal collection of faults, and by deformation of granular material. Each of the three frameworks can produce complex spatio-temporal patterns of earthquakes and faults. At present the existing data cannot distinguish unequivocally between the three different views on the nature of fault zones or determine their scale of relevance. However, in each observational category, the highest resolution results associated with mature large-displacement faults are compatible with the standard continuum-Euclidean framework. This can be explained by a positive feedback mechanism associated with strain weakening rheology and localization, which attracts the long-term evolution of faults toward progressive regularization and Euclidean geometry. A negative feedback mechanism associated with strain hardening during initial deformation phases and around persisting geometrical irregularities and conjugate sets of faults generates new fractures and granularity at different scales. We conclude that long-term deformation in the crust, including many aspects of the observed spatio-temporal complexity of earthquakes and faults, may be explained to first order within the continuum-Euclidean framework.

Ben-Zion, Y.; Sammis, C. G.

78

The Kunlun Fault  

NASA Technical Reports Server (NTRS)

The Kunlun fault is one of the gigantic strike-slip faults that bound the north side of Tibet. Left-lateral motion along the 1,500-kilometer (932-mile) length of the Kunlun has occurred uniformly for the last 40,000 years at a rate of 1.1 centimeter per year, creating a cumulative offset of more than 400 meters. In this image, two splays of the fault are clearly seen crossing from east to west. The northern fault juxtaposes sedimentary rocks of the mountains against alluvial fans. Its trace is also marked by lines of vegetation, which appear red in the image. The southern, younger fault cuts through the alluvium. A dark linear area in the center of the image is wet ground where groundwater has ponded against the fault. Measurements from the image of displacements of young streams that cross the fault show 15 to 75 meters (16 to 82 yards) of left-lateral offset. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) acquired the visible light and near infrared scene on July 20, 2000. Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and the U.S./Japan ASTER Science Team

2002-01-01

79

Salt lake Laguna de Fuente de Piedra (S-Spain) as Late Quaternary palaeoenvironmental archive  

NASA Astrophysics Data System (ADS)

This study deals with Late Quaternary palaeoenvironmental variability in Iberia reconstructed from terrestrial archives. In southern Iberia, endorheic basins of the Betic Cordilleras are relatively common and contain salt or fresh-water lakes due to subsurface dissolution of Triassic evaporites. Such precipitation or ground-water fed lakes (called Lagunas in Spanish) are vulnerable to changes in hydrology, climate or anthropogenic modifications. The largest Spanish salt lake, Laguna de Fuente de Piedra (Antequera region, S-Spain), has been investigated and serves as a palaeoenvironmental archive for the Late Pleistocene to Holocene time interval. Several sediment cores taken during drilling campaigns in 2012 and 2013 have revealed sedimentary sequences (up to 14 m length) along the shoreline. A multi-proxy study, including sedimentology, geochemistry and physical properties (magnetic susceptibility) has been performed on the cores. The sedimentary history is highly variable: several decimetre thick silty variegated clay deposits, laminated evaporites, and even few-centimetre thick massive gypsum crystals (i.e., selenites). XRF analysis was focussed on valuable palaeoclimatic proxies (e.g., S, Zr, Ti, and element ratios) to identify the composition and provenance of the sediments and to delineate palaeoenvironmental conditions. First age control has been realized by AMS-radiocarbon dating. The records start with approximately 2-3 m Holocene deposits and reach back to the middle of MIS 3 (GS-3). The sequences contain changes in sedimentation rates as well as colour changes, which can be summarized as brownish-beige deposits at the top and more greenish-grey deposits below as well as highly variegated lamination and selenites below ca. 6 m depth. The Younger Dryas, Bølling/Allerød, and the so-called Mystery Interval/Last Glacial Maximum have presumably been identified in the sediment cores and aligned to other climate records. In general, the cores of the Laguna de Fuente de Piedra show cyclic deposition including evaporitic sequences throughout the Holocene and Late Pleistocene, indicating higher fluxes and reworking of organic/inorganic carbon as well as other indicative proxy elements like Ti, Zr and Ca/Sr ratio during Late Pleistocene times. In order to achieve a better understanding of the palaeoenvironmental history in the study area further studies are planned which encompass biological/palaeontological indicators (e.g., pollen, diatoms) as well as another geochemical isotopic techniques on evaporitic deposits such as fluid inclusion analysis.

Höbig, Nicole; Melles, Martin; Reicherter, Klaus

2014-05-01

80

Fault detection and isolation  

NASA Astrophysics Data System (ADS)

In order for a current satellite-based navigation system (such as the Global Positioning System, GPS) to meet integrity requirements, there must be a way of detecting erroneous measurements, without help from outside the system. This process is called Fault Detection and Isolation (FDI). Fault detection requires at least one redundant measurement, and can be done with a parity space algorithm. The best way around the fault isolation problem is not necessarily isolating the bad measurement, but finding a new combination of measurements which excludes it.

Bernath, Greg

1994-02-01

81

Fault detection and isolation  

NASA Technical Reports Server (NTRS)

In order for a current satellite-based navigation system (such as the Global Positioning System, GPS) to meet integrity requirements, there must be a way of detecting erroneous measurements, without help from outside the system. This process is called Fault Detection and Isolation (FDI). Fault detection requires at least one redundant measurement, and can be done with a parity space algorithm. The best way around the fault isolation problem is not necessarily isolating the bad measurement, but finding a new combination of measurements which excludes it.

Bernath, Greg

1994-01-01

82

Behavioral-level fault simulation  

Microsoft Academic Search

An approach to fault simulation is presented in which behavioral fault models represent complex failures in VLSI designs. Errors are deliberately introduced into the description of a design that contains no faults. These errors can be fault values of variables that represent state or timing parameters, a faulty description that is substituted for part of the good description, or a

SUMIT GHOSH

1988-01-01

83

VSC transmission control under faults  

Microsoft Academic Search

This paper studies the VSC (voltage source converter) transmission control for fault conditions. A small-signal VSC transmission controller considers only small deviations around steady state and in case of faults there would be large overvoltages and overcurrents. An additional fault controller is introduced to reduce transient overvoltages and overcurrents which occur in case of faults. Parallel configuration is used in

L. A. Lamont; D. Jovcic; K. Abbott

2004-01-01

84

Response of shoal grass, Halodule wrightii, to extreme winter conditions in the Lower Laguna Madre, Texas  

USGS Publications Warehouse

Effects of a severe freeze on the shoal grass, Halodule wrightii, were documented through analysis of temporal and spatial trends in below-ground biomass. The coincidence of the second lowest temperature (-10.6??C) in 107 years of record, 56 consecutive hours below freezing, high winds and extremely low water levels exposed the Laguna Madre, TX, to the most severe cold stress in over a century. H. wrightii tolerated this extreme freeze event. Annual pre- and post-freeze surveys indicated that below-ground biomass estimated from volume was Unaffected by the freeze event. Nor was there any post-freeze change in biomass among intertidal sites directly exposed to freezing air temperatures relative to subtidal sites which remained submerged during the freezing period.

Hicks, D. W.; Onuf, C. P.; Tunnell, J. W.

1998-01-01

85

Remote sensing and numerical modeling of suspended sediment in Laguna de Terminos, Campeche, Mexico  

NASA Technical Reports Server (NTRS)

It is necessary to understand the complex physical processes at work in coastal lagoons in order to manage them effectively. Improved methods of data collection and analysis must be found to provide synoptic, timely hydrodynamic information because of the sheer size of some lagoons and the difficulty of acquiring in situ data (particularly in the tropics). This paper summarizes research to model salinity and suspended sediment distributions in Laguna de Terminos, Mexico, using (1) a coupled hydrodynamic and dispersion model and (2) analysis of two Landsat Thematic Mapper images collected on November 25, 1984 and April 24, 1987. Atmospherically corrected chromaticity data derived from Thermatic Mapper data were significantly correlated with modeled total suspended sediment concentrations for the two dates. Comparison between numerically modeled and remotely sensed suspended sediment maps at 1.5 x 1.5 km resolution yielded a covariation map useful for identifying areas of discrepancy between the remotely sensed data and model output.

Jensen, John R.; Kjerfve, Bjorn; Ramsey, Elijah W., III; Magill, Karen E.; Medeiros, Carmen

1989-01-01

86

Late Pleistocene-early Holocene karst features, Laguna Madre, south Texas: A record of climate change  

SciTech Connect

A Pleistocene coquina bordering Laguna Madre, south Texas, contains well-developed late Pleistocene-early Holocene karst features (solution pipes and caliche crusts) unknown elsewhere from coastal Texas. The coquina accumulated in a localized zone of converging longshore Gulf currents along a Gulf beach. The crusts yield {sup 14}C dates of 16,660 to 7630 B.P., with dates of individual crust horizons becoming younger upwards. The karst features provide evidence of regional late Pleistocene-early Holocene climate changes. Following the latest Wisconsinan lowstand 18,000 B.P. the regional climate was more humid and promoted karst weathering. Partial dissolution and reprecipitation of the coquina formed initial caliche crust horizons; the crust later thickened through accretion of additional carbonate laminae. With the commencement of the Holocene approximately 11,000 B.P. the regional climate became more arid. This inhibited karstification of the coquina, and caliche crust formation finally ceased about 7000 B.P.

Prouty, J.S. [Texas A& M Univ., Corpus Christi, TX (United States)

1996-09-01

87

Foraminifera Assemblages in Laguna Torrecilla- Puerto Rico: an Environmental Micropaleontology Approach.  

NASA Astrophysics Data System (ADS)

Foraminiferal assemblages (Ammonia becarii cf. typica - A. becarii cf. tepida - Triloculina spp.) from 30 cm cores taken at Laguna Torrecilla, a polluted estuary, contain a relative high occurrence of deformed tests (up to 13%). Such deformities (i.e., double tests, aberrant tests) are mostly found within the miliolids (Triloculina spp.) while the rotaliids (Ammonia spp.) show fewer deformities (i.e., extended proloculi, stunted tests). Preliminary results for heavy metal analysis (ACTLABS Laboratories-Canada) from bulk sediment samples show concentrations below toxicity levels except for copper. Copper concentrations (50- 138 ppm) fall between the ERL (Effect Range Low) and ERM (Effect Range Median) values representing possible to occasional detrimental effects to the aquatic environment. Organic matter content (loss-on-ignition) ranging from 10-23%, coupled with pyritized tests and framboidal pyrite, indicates low oxygen conditions. Ammonia becarii cf. typica and A. becarii cf. tepida showed no significant variation in size with sample depth. However, forma tepida was not found in the intervals with highest organic concentrations. The abundance of A. becarii, which is a species highly resistant to environmental stresses, appears to be related to hypoxia events. Ammonia-Elphidium index values, a previously established indicator of hypoxia, are 80-100, reflecting the lack of Elphidium spp. Apparently reduced oxygen conditions at Laguna Torrecilla exceeded the tolerance levels of Elphidium spp. In addition, diversity indices show that there has been temporal variability in terms of abundance and distribution of foraminifera. Foraminiferal assemblages coupled with diversity indices and organic matter content indicates that Torrecilla Lagoon has undergone several episodes of hypoxia. Such conditions could explain the relatively high percentage of test deformities, although elevated copper concentrations may be a compounding factor.

Martinez-Colon, M.; Hallock, P.

2006-12-01

88

Faults and Folds Animation  

NSDL National Science Digital Library

This animation explores the forces and processes that deform rocks by creating folds, faults, and mountain ranges. You will learn how landmasses move, see the resulting deformation, and learn how this deformation relates to plate tectonics.

2002-01-01

89

Tolerance to Unbounded Byzantine Faults  

Microsoft Academic Search

An ideal approach to deal with faults in large-scale distributed systems is to contain the effects of faults as locally as possible and, additionally, to ensure some type of tolerance within each fault-affected locality. Existing results using this approach accommodate only limited faults (such as crashes) or assume that fault occurrence is bounded in space and\\/or time. In this paper,

Mikhail Nesterenko; Anish Arora

2002-01-01

90

Fault tolerant magnetic bearings  

SciTech Connect

A fault tolerant magnetic bearing system was developed and demonstrated on a large flexible-rotor test rig. The bearing system comprises a high speed, fault tolerant digital controller, three high capacity radial magnetic bearings, one thrust bearing, conventional variable reluctance position sensors, and an array of commercial switching amplifiers. Controller fault tolerance is achieved through a very high speed voting mechanism which implements triple modular redundancy with a powered spare CPU, thereby permitting failure of up to three CPU modules without system failure. Amplifier/cabling/coil fault tolerance is achieved by using a separate power amplifier for each bearing coil and permitting amplifier reconfiguration by the controller upon detection of faults. This allows hot replacement of failed amplifiers without any system degradation and without providing any excess amplifier kVA capacity over the nominal system requirement. Implemented on a large (2440 mm in length) flexible rotor, the system shows excellent rejection of faults including the failure of three CPUs as well as failure of two adjacent amplifiers (or cabling) controlling an entire stator quadrant.

Maslen, E.H.; Sortore, C.K.; Gillies, G.T.; Williams, R.D.; Fedigan, S.J. [Univ. of Virginia, Charlottesville, VA (United States); Aimone, R.J. [Mobile Technology Co., Paulsboro, NJ (United States)

1999-07-01

91

Triggered surface slips in southern California associated with the 2010 El Mayor-Cucapah, Baja California, Mexico, earthquake  

USGS Publications Warehouse

Triggered slip in the Yuha Desert area occurred along more than two dozen faults, only some of which were recognized before the April 4, 2010, El Mayor-Cucapah earthquake. From east to northwest, slip occurred in seven general areas: (1) in the Northern Centinela Fault Zone (newly named), (2) along unnamed faults south of Pinto Wash, (3) along the Yuha Fault (newly named), (4) along both east and west branches of the Laguna Salada Fault, (5) along the Yuha Well Fault Zone (newly revised name) and related faults between it and the Yuha Fault, (6) along the Ocotillo Fault (newly named) and related faults to the north and south, and (7) along the southeasternmost section of the Elsinore Fault. Faults that slipped in the Yuha Desert area include northwest-trending right-lateral faults, northeast-trending left-lateral faults, and north-south faults, some of which had dominantly vertical offset. Triggered slip along the Ocotillo and Elsinore Faults appears to have occurred only in association with the June 14, 2010 (Mw5.7), aftershock. This aftershock also resulted in slip along other faults near the town of Ocotillo. Triggered offset on faults in the Yuha Desert area was mostly less than 20 mm, with three significant exceptions, including slip of about 50–60 mm on the Yuha Fault, 40 mm on a fault south of Pinto Wash, and about 85 mm on the Ocotillo Fault. All triggered slips in the Yuha Desert area occurred along preexisting faults, whether previously recognized or not.

Rymer, Michael J.; Treiman, Jerome A.; Kendrick, Katherine J.; Lienkaemper, James J.; Weldon, Ray J.; Bilham, Roger; Wei, Meng; Fielding, Eric J.; Hernandez, Janis L.; Olson, Brian P. E.; Irvine, Pamela J.; Knepprath, Nichole; Sickler, Robert R.; Tong, Xiaopeng; Siem, Martin E.

2011-01-01

92

Packaged Fault Model for Geometric Segmentation of Active Faults Into Earthquake Source Faults  

NASA Astrophysics Data System (ADS)

In Japan, the empirical formula proposed by Matsuda (1975) mainly based on the length of the historical surface fault ruptures and magnitude, is generally applied to estimate the size of future earthquakes from the extent of existing active faults for seismic hazard assessment. Therefore validity of the active fault length and defining individual segment boundaries where propagating ruptures terminate are essential and crucial to the reliability for the accurate assessments. It is, however, not likely for us to clearly identify the behavioral earthquake segments from observation of surface faulting during the historical period, because most of the active faults have longer recurrence intervals than 1000 years in Japan. Besides uncertainties of the datasets obtained mainly from fault trenching studies are quite large for fault grouping/segmentation. This is why new methods or criteria should be applied for active fault grouping/segmentation, and one of the candidates may be geometric criterion of active faults. Matsuda (1990) used _gfive kilometer_h as a critical distance for grouping and separation of neighboring active faults. On the other hand, Nakata and Goto (1998) proposed the geometric criteria such as (1) branching features of active fault traces and (2) characteristic pattern of vertical-slip distribution along the fault traces as tools to predict rupture length of future earthquakes. The branching during the fault rupture propagation is regarded as an effective energy dissipation process and could result in final rupture termination. With respect to the characteristic pattern of vertical-slip distribution, especially with strike-slip components, the up-thrown sides along the faults are, in general, located on the fault blocks in the direction of relative strike-slip. Applying these new geometric criteria to the high-resolution active fault distribution maps, the fault grouping/segmentation could be more practically conducted. We tested this model successfully on the active faults generated the 1943 Tottori earthquake, the Chojagahara-Yoshii fault zone in Chugoku district in southwest Japan, as well as the active fault system in northern Luzon, the Philippines. Thus, we name this conceptual model as _gPackaged Fault Model_h and call the active faults grouped by the model as _gPackaged Faults_h for individual earthquake source faults. Moreover, we come to know that active fault mapping with _gPackaged Fault Model_h in mind enables us to find many new active fault traces (e.g., the Shigenobu fault along the MTL in Japan).

Nakata, T.; Kumamoto, T.

2004-12-01

93

Fault reactivation control on normal fault growth: an experimental study  

NASA Astrophysics Data System (ADS)

Field studies frequently emphasize how fault reactivation is involved in the deformation of the upper crust. However, this phenomenon is generally neglected (except in inversion models) in analogue and numerical models performed to study fault network growth. Using sand/silicon analogue models, we show how pre-existing discontinuities can control the geometry and evolution of a younger fault network. The models show that the reactivation of pre-existing discontinuities and their orientation control: (i) the evolution of the main fault orientation distribution through time, (ii) the geometry of relay fault zones, (iii) the geometry of small scale faulting, and (iv) the geometry and location of fault-controlled basins and depocenters. These results are in good agreement with natural fault networks observed in both the Gulf of Suez and Lake Tanganyika. They demonstrate that heterogeneities such as pre-existing faults should be included in models designed to understand the behavior and the tectonic evolution of sedimentary basins.

Bellahsen, Nicolas; Daniel, Jean Marc

2005-04-01

94

Unrest within a large rhyolitic magma system at Laguna del Maule volcanic field (Chile) from 2007 through 2013: geodetic measurements and numerical models  

NASA Astrophysics Data System (ADS)

The Laguna del Maule (LdM) volcanic field is remarkable for its unusual concentration of post-glacial rhyolitic lava coulées and domes that erupted between 25 and 2 thousand years ago. Covering more than 100 square kilometers, they erupted from 24 vents encircling a lake basin approximately 20 km in diameter on the range crest of the Andes. Geodetic measurements at the LdM volcanic field show rapid uplift since 2007 over an area more than 20 km in diameter that is centered on the western portion of the young rhyolite domes. By quantifying this active deformation and its evolution with time, we aim to investigate the storage conditions and dynamic processes in the underlying rhyolitic reservoir that drive the ongoing inflation. Analyzing interferometric synthetic aperture radar (InSAR) data, we track the rate of deformation. The rate of vertical uplift is negligible from 2003 to 2004, accelerates from at least 200 mm/yr in 2007 to more than 300 mm/yr in 2012, and then decreases to 200mm/yr in early 2013. To describe the deformation, we use a simple model that approximates the source as a 8 km-by-6 km sill at a depth of 5 km, assuming a rectangular dislocation in a half space with uniform elastic properties. Between 2007 and 2013, the modeled sill increased in volume by at least 190 million cubic meters. Four continuous GPS stations installed in April 2012 around the lake confirm this extraordinarily high rate of vertical uplift and a substantial rate of radial expansion. As of June 2013, the rapid deformation persists in the InSAR and GPS data. To describe the spatial distribution of material properties at depth, we are developing a model using the finite element method. This approach can account for geophysical observations, including magneto-telluric measurements, gravity surveys, and earthquake locations. It can also calculate changes in the local stress field. In particular, a large increase in stress in the magma chamber roof could lead to the initiation and/or reactivation of the ring faults. Potential evidence for fault reactivation is the detection of diffuse soil degassing of CO2 with concentrations reaching 5-7% near the center of deformation. We therefore consider several hypotheses for the processes driving the deformation, including: (1) an intrusion of basalt into the base of a melt-rich layer of rhyolite leading to heating, bubble growth and subsequent increase pressure in the reservoir, and/or (2) inflation of a hydrothermal system above the rhyolite melt layer.

Le Mevel, H.; Cordova, L.; Ali, S. T.; Feigl, K. L.; DeMets, C.; Williams-Jones, G.; Tikoff, B.; Singer, B. S.

2013-12-01

95

Thermochronological investigation of fault zones  

NASA Astrophysics Data System (ADS)

The timing of faulting episodes can be constrained by radiometric dating of fault-zone rocks. Fault-zone material suitable for dating is produced by tectonic processes, such as (1) fragmentation of host rocks, followed by grain-size reduction and recrystallization to form mica and clay minerals, (2) secondary heating/melting of host rocks by frictional fault motions, and (3) mineral vein formation as a result of fluid advection associated with the fault motions. The thermal regime of fault zones consists primarily of the following three factors: (a) regional geothermal structure across the fault zone and background thermal history of studied province bounded by fault systems, (b) frictional heating of wall rocks by fault motions, and (c) heating of host rocks by hot fluid advection in and around the fault zone. Thermochronological methods widely applied in fault zones are K-Ar (40Ar/39Ar), fission-track, and U-Th methods, for which methodological principles as well as analytical procedures are briefly described. The thermal sensitivities of individual thermochronological systems are then reviewed, which critically control the response of each method against the thermal processes. Based on the knowledge above, representative examples as well as key issues are highlighted to date fault gouges, pseudotachylytes, mylonites and carbonate veins, placing new constraints upon geological, geomorphological and seismological frames. Finally, the Nojima Fault is presented as an example for multiple applications of thermochronological methods in a complex fault zone.

Tagami, Takahiro

2012-05-01

96

15,000-yr pollen record of vegetation change in the high altitude tropical Andes at Laguna Verde Alta, Venezuela  

Microsoft Academic Search

Pollen analysis of sediments from a high-altitude (4215 m), Neotropical (9°N) Andean lake was conducted in order to reconstruct local and regional vegetation dynamics since deglaciation. Although deglaciation commenced ?15,500 cal yr B.P., the area around the Laguna Verde Alta (LVA) remained a periglacial desert, practically unvegetated, until about 11,000 cal yr B.P. At this time, a lycopod assemblage bearing

Valentí Rull; Mark B. Abbott; Pratigya J. Polissar; Alexander P. Wolfe; Maximiliano Bezada; Raymond S. Bradley

2005-01-01

97

15,000-yr pollen record of vegetation change in the high altitude tropical Andes at Laguna Verde Alt  

Microsoft Academic Search

Pollen analysis of sediments from a high-altitude (4215 m), Neotropical (9-N) Andean lake was conducted in order to reconstruct local and regional vegetation dynamics since deglaciation. Although deglaciation commenced ?15,500 cal yr B. P., the area around the Laguna Verde Alta (LVA) remained a periglacial desert, practically unvegetated, until about 11,000 cal yr B. P. At this time, a lycopod

Valenti' Rull; Mark B. Abbott; Pratigya J. Polissar; Alexander P. Wolfe

98

Human Impact Since Medieval Times and Recent Ecological Restorationin a Mediterranean Lake: The Laguna Zoñar, Southern Spain  

Microsoft Academic Search

The multidisciplinary study of sediment cores from Laguna Zoar (3729?00?? N, 441?22?? W, 300 m a.s.l., Andaluca, Spain)\\u000a provides a detailed record of environmental, climatic and anthropogenic changes in a Mediterranean watershed since Medieval\\u000a times, and an opportunity to evaluate the lake restoration policies during the last decades. The paleohydrological reconstructions\\u000a show fluctuating lake levels since the end of the Medieval

Blas L. Valero-Garcés; Penélope González-Sampériz; Ana Navas; Javier Machín; Pilar Mata; Antonio Delgado-Huertas; Roberto Bao; Ana Moreno; José S. Carrión; Antje Schwalb; Antonio González-Barrios

2006-01-01

99

Geological setting and paleomagnetism of the Eocene red beds of Laguna Brava Formation (Quebrada Santo Domingo, northwestern Argentina)  

NASA Astrophysics Data System (ADS)

The red bed succession cropping out in the Quebrada Santo Domingo in northwestern Argentina had been for long considered as Upper Triassic-Lower Jurassic in age based on weak radiometric and paleontological evidence. Preliminary paleomagnetic data confirmed the age and opened questions about the nature of fossil footprints with avian features discovered in the section. Recently the stratigraphic scheme was reviewed with the identification of previously unrecognized discontinuities, and a radiometric dating obtained in a tuff, indicated an Eocene age for the Laguna Brava Formation and the fossil bird footprints, much younger than the previously assigned. We present a detailed paleomagnetic study interpreted within a regional tectonic and stratigraphic framework, looking for an explanation for the misinterpretation of the preliminary paleomagnetic data. The characteristic remanent magnetizations pass a tilt test and a reversal test. The main magnetic carrier is interpreted to be low Ti titanomagnetites and to a lesser extent hematite. The characteristic remanent magnetization would be essentially detrital. The obtained paleomagnetic pole (PP) for the Laguna Brava Formation has the following geographic coordinates and statistical parameters: N = 29, Lon. = 184.5° E, Lat. = 75.0° S, A95 = 5.6° and K = 23.7. When this PP is compared with another one with similar age obtained in an undeformed area, a declination anomaly is recognized. This anomaly can be interpreted as Laguna Brava Formation belonging to a structural block that rotated about 16° clockwise along a vertical axis after about 34 Ma. This block rotation is consistent with the regional tectonic framework, and would have caused the fortuitous coincidence of the PP with Early Jurassic poles. According to the interpreted magnetostratigraphic correlation, the Laguna Brava Formation would have been deposited during the Late Eocene with a mean sedimentation rate of about 1.4 cm per thousand years, probably in relation to the onset of the Andean deformation.

Vizán, H.; Geuna, S.; Melchor, R.; Bellosi, E. S.; Lagorio, S. L.; Vásquez, C.; Japas, M. S.; Ré, G.; Do Campo, M.

2013-01-01

100

Ikaite precipitation in a lacustrine environment - implications for palaeoclimatic studies using carbonates from Laguna Potrok Aike (Patagonia, Argentina)  

NASA Astrophysics Data System (ADS)

The monoclinic mineral ikaite (CaCO3 · 6H2O) and its pseudomorphs are potentially important archives for palaeoenvironmental reconstructions. Natural ikaite occurs in a small temperature range near freezing point and is reported mainly from marine and only rarely from continental aquatic environments. Ikaite transforms to more stable anhydrous forms of CaCO3 after an increase in temperature or when exposed to atmospheric conditions. The knowledge about conditions for natural ikaite formation, its stable isotope fractionation factors and isotopic changes during transformation to calcite is very restricted. Here, for the first time, primary precipitation of idiomorphic ikaite and its calcite pseudomorphs are reported from a subsaline lake, Laguna Potrok Aike, in southern Argentina. The calculated stable oxygen isotope fractionation factor between lake water and ikaite-derived calcite (?PAI = 1.0324 at a temperature of 4.1 °C) is close to but differs from that of primarily inorganically precipitated calcite. Pseudomorphs after ikaite rapidly disintegrate into calcite powder that is indistinguishable from ?m-sized calcite crystals in the sediment record of Laguna Potrok Aike suggesting an ikaite origin of sedimentary calcites. Therefore, the Holocene carbonates of Laguna Potrok Aike have the potential to serve as a recorder of past hydrological variation.

Oehlerich, Markus; Mayr, Christoph; Griesshaber, Erika; Lücke, Andreas; Oeckler, Oliver M.; Ohlendorf, Christian; Schmahl, Wolfgang W.; Zolitschka, Bernd

2013-07-01

101

Fault terminations, Seminoe Mountains, Wyoming  

SciTech Connect

Two basement-involved faults terminate in folds in the Seminoe Mountains. Mesoscopic and macroscopic structures in sedimentary rocks provide clues to the interrelationship of faults and folds in this region, and on the linkage between faulting and folding in general. The Hurt Creek fault trends 320[degree] and has maximum separation of 1.5 km measured at the basement/cover contact. Separation on the fault decreases upsection to zero within the Jurassic Sundance Formation. Unfaulted rock units form an anticline around the fault tip. The complementary syncline is angular with planar limbs and a narrow hinge zone. The syncline axial trace intersects the fault in the footwall at the basement/cover cut-off. Map patterns are interpreted to show thickening of Mesozoic units adjacent to the syncline hinge. In contrast, extensional structures are common in the faulted anticline within the Permian Goose Egg and Triassic Chugwater Formations. A hanging wall splay fault loses separation into the Goose Egg formation which is thinned by 50% at the fault tip. Mesoscopic normal faults are oriented 320--340[degree] and have an average inclination of 75[degree] SW. Megaboudins of Chugwater are present in the footwall of the Hurt Creek fault, immediately adjacent to the fault trace. The Black Canyon fault transported Precambrian-Pennsylvanian rocks over Pennsylvanian Tensleep sandstone. This fault is layer-parallel at the top of the Tensleep and loses separation along strike into an unfaulted syncline in the Goose Egg Formation. Shortening in the pre-Permian units is accommodated by slip on the basement-involved Black Canyon fault. Equivalent shortening in Permian-Cretaceous units occurs on a system of thin-skinned'' thrust faults.

Dominic, J.B.; McConnell, D.A. (Univ. of Akron, OH (United States). Dept. of Geology)

1992-01-01

102

An Empirical Comparison of Software Fault Tolerance and Fault Elimination  

Microsoft Academic Search

The authors compared two major approaches to the improvement of software-software fault elimination and software fault tolerance-by examination of the fault detection (and tolerance, where applicable) of five techniques: run-time assertions, multiversion voting, functional testing augmented by structural testing, code reading by stepwise abstraction, and static data-flow analysis. The focus was on characterizing the sets of faults detected by the

Timothy J. Shimeall; Nancy G. Leveson

1991-01-01

103

Computer hardware fault administration  

DOEpatents

Computer hardware fault administration carried out in a parallel computer, where the parallel computer includes a plurality of compute nodes. The compute nodes are coupled for data communications by at least two independent data communications networks, where each data communications network includes data communications links connected to the compute nodes. Typical embodiments carry out hardware fault administration by identifying a location of a defective link in the first data communications network of the parallel computer and routing communications data around the defective link through the second data communications network of the parallel computer.

Archer, Charles J. (Rochester, MN); Megerian, Mark G. (Rochester, MN); Ratterman, Joseph D. (Rochester, MN); Smith, Brian E. (Rochester, MN)

2010-09-14

104

Ius Chasma Fault  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-415, 8 July 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 'text-book example' of an offset in layered rock caused by a fault. The offset is most easily seen near the upper right of the image. The martian crust is faulted, and the planet has probably experienced 'earthquakes' (or, marsquakes) in the past. This scene is located on the floor of Ius Chasma near 7.8oS, 80.6oW. Sunlight illuminates the scene from the upper left.

2003-01-01

105

Shallow faults mapped with seismic reflections: Lost River Fault, Idaho  

Microsoft Academic Search

A high-resolution seismic-reflection survey, conducted at the intersection of Arentson Gulch road and the western splay of the Lost River fault scarp in central Idaho, defines a bedrock surface about 80 m deep which is segmented by several faults forming graben structures. Six meters of total fault displacement can be interpreted on the bedrock reflector while only 1 to 2

Mubarik Ali; Richard D. Miller; Don W. Steeples

1991-01-01

106

Shallow faults mapped with seismic reflections: Lost River fault, Idaho  

Microsoft Academic Search

A high-resolution seismic-reflection survey, conducted at the intersection of Arentson Gulch road and the western splay of the Lost River fault scarp in central Idaho, defines a bedrock surface about 80 m deep which is segmented by several faults forming graben structures. Six meters of total fault displacement can be interpreted on the bedrock reflector while only 1 to 2

Mubarik Ali; Richard D. Miller; Don W. Steeples

1991-01-01

107

The Maars of the Tuxtla Volcanic Field: the Example of 'laguna Pizatal'  

NASA Astrophysics Data System (ADS)

Los Tuxtlas Volcanic Field (TVF), also known as Los Tuxtlas massif, is a structure of volcanic rocks rising conspicuously in the south-central part of the coastal plains of eastern Mexico. The TVF seems related to the upper cretaceous magmatism of the NW part of the Gulf's margin (e.g. San Carlos and Sierra de Tamaulipas alkaline complexes) rather than to the nearby Mexican Volcanic Belt. The volcanism in this field began in late Miocene and has continued in historical times, The TVF is composed of 4 large volcanoes (San Martin Tuxtla, San Martin Pajapan, Santa Marta, Cerro El Vigia), at least 365 volcanic cones and 43 maars. In this poster we present the distribution of the maars, their size and depths. These maars span from a few hundred km to almost 1 km in average diameter, and a few meters to several tens of meters in depth; most of them filled with lakes. As an example on the nature of these structures we present our results of the ongoing study of 'Laguna Pizatal or Pisatal' (18° 33'N, 95° 16.4'W, 428 masl) located some 3 km from the village of Reforma, on the western side of San Martin Tuxtla volcano. Laguna Pisatal is a maar some 500 meters in radius and a depth about 40 meters from the surrounding ground level. It is covered by a lake 200 m2 in extent fed by a spring discharging on its western side. We examined a succession of 15 layers on the margins of the maar, these layers are blast deposits of different sizes interbedded by surge deposits. Most of the contacts between layers are irregular; which suggests scouring during deposition of the upper beds. This in turn suggests that the layers were deposited in a rapid series of explosions, which mixed juvenile material with fragments of the preexisting bedrock. We were unable to find the extent of these deposits since the surrounding areas are nowadays sugar cane plantations and the lake has overspilled in several occassions.

Espindola, J.; Zamora-Camacho, A.; Hernandez-Cardona, A.; Alvarez del Castillo, E.; Godinez, M.

2013-12-01

108

Fault Rate Acceleration and Low Angle Normal Faulting: The Hunter Mountain Fault, California.  

NASA Astrophysics Data System (ADS)

The Panamint Valley, Hunter Mountain, Saline Range (PHS) faults are, together with the Death Valley and Owens Valley faults, one of the three major fault zones within the Eastern California Shear Zone (ECSZ). The ECSZ is the most active fault system bounding the Basin and Range to the southwest with approximately 10 mm/yr of cumulative slip along strike-slip and trans-tensional segments. Interferometry Synthetic Aperture Radar (InSAR) is a geodetic technique that allows measurement of ground motion at a mm/yr accuracy over large areas with a high measurement sampling. We processed a large number of data to investigate ground motion in the PHS fault system to shed light on the interseismic strain accumulation and its relation to the fault geometry. Results indicate high strain rate over the Hunter Mountain fault, possibly showing slip rate acceleration of the fault since inception time. The locking depth of the fault inferred from elastic modeling of interseismic strain accumulation is on the order of a few kilometers, significantly shallower than for neighboring faults. The shallow locking depth inferred for the Hunter Mountain fault corresponds to the extension at depth of two suggested bounding low angle normal faults. This finding reinforced recent field study findings about possible activity of the low angle normal fault system.

Gourmelen, N.; Amelung, F.; Dixon, T.; Manzo, M.; Casu, F.; Pepe, A.; Lanari, R.

2008-05-01

109

Impacts of Fault Geometry on Fault System Behaviors  

NASA Astrophysics Data System (ADS)

Complexity in earthquake populations arises primarily due to two components: friction and fault geometry. We present preliminary investigations into contributions to event population complexity due to fault geometry variation. In one key application, we investigate probabilities of events continuing along multiple, en echelon fault segments in both compressional and extensional regimes as a function of distance between the segments and segment overlap. These and other results are produced in the course of developing the extended finite element method, XFEM (e.g. [Dolbow, Moes, and Belytschko, 2001]), for static, quasistatic, and dynamic rupture problems on complicated fault networks. This method, part of a broader class of mesh-free methods, allow faults to be included nearly arbitrarily in a simulation, enabling many simulations with varying fault geometries to be conducted with minimal remeshing. We introduce the enforcement of failure criteria in dynamic rupture problems and test the method through a series of two-dimensional static and dynamic benchmarks. We also introduce a novel, ``two and a half-dimensional'' formulation, where two-dimensional plates intersect at faults that include a dip parameter which can vary along-strike. This enables us to model fault systems with strike-slip, thrust, normal, and mixed-mode faults. To demonstrate this capability, we examine fault systems composed of faults taken from the SCEC Community Fault Model Surface Traces. These results demonstrate the feasibility of the XFEM for both static and dynamic rupture problems. Furthermore, we demonstrate usage of the XFEM in studies with uncertain fault geometry, and enable new studies of fault system behaviors due to fault geometry.

Coon, E. T.; Shaw, B. E.; Spiegelman, M. W.

2009-12-01

110

Fault Detection in Routing Protocols  

Microsoft Academic Search

Routing protocol faults cause problems ranging from an inability to communicate to excessive routing overhead. This paper proposes a system for detecting a wide range of routing protocol faults. Our system deploys virtual routers called RouteMonitors to monitor a routing protocol. We de- ployed RouteMonitors in the MBone's DVMRP infrastruc- ture and uncovered a number of faults. We were also

Daniel Massey; Bill Fenner

1999-01-01

111

Improving fault handling software techniques  

Microsoft Academic Search

The paper presents the new software library supporting development of the fault-robust applications. The main goals of the proposed software hardening mechanisms are: usage simplicity for the programmer, independence from the development tool, effectiveness in terms of fault coverage, low static and dynamic overheads. The paper describes implemented software mechanisms and discusses their effectiveness verified with fault injection experiments.

Piotr Gawkowski; Tomasz Rutkowski; Janusz Sosnowski

2010-01-01

112

Modelling the Fault Correction Process  

Microsoft Academic Search

In general, software reliability models have focused on modeling and predicting failure occurrence and have not given equal priority to modeling the fault correction process. However, there is a need for fault correction prediction, because there are important applications that fault correction modeling and prediction support. These are the following: predicting whether reliability goals have been achieved, developing stopping rules

Norman F. Schneidewind

2001-01-01

113

Fault testing quantum switching circuits  

Microsoft Academic Search

Test pattern generation is an electronic design automation tool that attempts to find an input (or test) sequence that, when applied to a digital circuit, enables one to distinguish between the correct circuit behavior and the faulty behavior caused by particular faults. The effectiveness of this classical method is measured by the fault coverage achieved for the fault model and

Jacob Biamonte; Marek Perkowski

2005-01-01

114

Row fault detection system  

DOEpatents

An apparatus and program product check for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

Archer, Charles Jens (Rochester, MN); Pinnow, Kurt Walter (Rochester, MN); Ratterman, Joseph D. (Rochester, MN); Smith, Brian Edward (Rochester, MN)

2010-02-23

115

Fault tolerant anonymous channel  

Microsoft Academic Search

Previous anonymous channels, called MIX nets, do not workif one center stops. This paper shows new anonymous channels which allowless than a half of faulty centers. A fault tolerant multivalued electionscheme is obtained automatically. A very efficient ZKIP for the centersis also presented.

Wakaha Ogata; Kaoru Kurosawa; Kazue Sako; Kazunori Takatani

1997-01-01

116

Row fault detection system  

DOEpatents

An apparatus, program product and method checks for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

Archer, Charles Jens (Rochester, MN) [Rochester, MN; Pinnow, Kurt Walter (Rochester, MN) [Rochester, MN; Ratterman, Joseph D. (Rochester, MN) [Rochester, MN; Smith, Brian Edward (Rochester, MN) [Rochester, MN

2008-10-14

117

Row fault detection system  

DOEpatents

An apparatus, program product and method check for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

Archer, Charles Jens (Rochester, MN); Pinnow, Kurt Walter (Rochester, MN); Ratterman, Joseph D. (Rochester, MN); Smith, Brian Edward (Rochester, MN)

2012-02-07

118

Formal Fault Tree Semantics  

Microsoft Academic Search

In train control systems, more and more (electro-)mechanical devices are substituted by software based devices. To sustain the high level safety standards for these embedded systems, we propose the integration of fault tree analysis and formal methods. This combines two important safety analysis methods from the involved domains of engineering and software development. Our approach proposes to build a formal

Gerhard Schellhorn; Andreas Thums; Wolfgang Reif Lehrstuhl

2002-01-01

119

Fault isolation techniques  

NASA Technical Reports Server (NTRS)

Three major areas that are considered in the development of an overall maintenance scheme of computer equipment are described. The areas of concern related to fault isolation techniques are: the programmer (or user), company and its policies, and the manufacturer of the equipment.

Dumas, A.

1981-01-01

120

Earthquakes and fault creep on the northern San Andreas fault  

USGS Publications Warehouse

At present there is an absence of both fault creep and small earthquakes on the northern San Andreas fault, which had a magnitude 8 earthquake with 5 m of slip in 1906. The fault has apparently been dormant after the 1906 earthquake. One possibility is that the fault is 'locked' in some way and only produces great earthquakes. An alternative possibility, presented here, is that the lack of current activity on the northern San Andreas fault is because of a lack of sufficient elastic strain after the 1906 earthquake. This is indicated by geodetic measurements at Fort Ross in 1874, 1906 (post-earthquake), and 1969, which show that the strain accumulation in 1969 (69 ?? 10-6 engineering strain) was only about one-third of the strain release (rebound) in the 1906 earthquake (200 ?? 10-6 engineering strain). The large difference in seismicity before and after 1906, with many strong local earthquakes from 1836 to 1906, but only a few strong earthquakes from 1906 to 1976, also indicates a difference of elastic strain. The geologic characteristics (serpentine, fault straightness) of most of the northern San Andreas fault are very similar to the characteristics of the fault south of Hollister, where fault creep is occurring. Thus, the current absence of fault creep on the northern fault segment is probably due to a lack of sufficient elastic strain at the present time. ?? 1979.

Nason, R.

1979-01-01

121

Estimating floodplain sedimentation in the Laguna de Santa Rosa, Sonoma County, CA  

USGS Publications Warehouse

We present a conceptual and analytical framework for predicting the spatial distribution of floodplain sedimentation for the Laguna de Santa Rosa, Sonoma County, CA. We assess the role of the floodplain as a sink for fine-grained sediment and investigate concerns regarding the potential loss of flood storage capacity due to historic sedimentation. We characterized the spatial distribution of sedimentation during a post-flood survey and developed a spatially distributed sediment deposition potential map that highlights zones of floodplain sedimentation. The sediment deposition potential map, built using raster files that describe the spatial distribution of relevant hydrologic and landscape variables, was calibrated using 2 years of measured overbank sedimentation data and verified using longer-term rates determined using dendrochronology. The calibrated floodplain deposition potential relation was used to estimate an average annual floodplain sedimentation rate (3.6 mm/year) for the ~11 km2 floodplain. This study documents the development of a conceptual model of overbank sedimentation, describes a methodology to estimate the potential for various parts of a floodplain complex to accumulate sediment over time, and provides estimates of short and long-term overbank sedimentation rates that can be used for ecosystem management and prioritization of restoration activities.

Curtis, Jennifer A.; Flint, Lorraine E.; Hupp, Cliff R.

2013-01-01

122

Vegetation and climate history from Laguna de Río Seco, Sierra Nevada, southern Spain  

NASA Astrophysics Data System (ADS)

The largest mountain range in southern Spain - the Sierra Nevada - is an immense landscape with a rich biological and cultural heritage. Rising to 3,479 m at the summit of Mulhacén, the range was extensively glaciated during the late Pleistocene. Subsequent melting of cirque glaciers allowed formation of numerous small lakes and wetlands. One south-facing basin contains Laguna de Río Seco, a small lake at ca. 3020 m elevation, presently above potential treeline. Pollen analysis of sediment cores documents over 11,000 calendar years of vegetation change there. The early record, to ca. 5,700 cal yr BP, is dominated by pine pollen, with birch, deciduous oak, and grass, with an understory of shrubs types. Pine trees probably never grew at the elevation of the lake, but aquatic microfossils indicate lake levels were highest prior to ca. 7,800 cal yr BP, perhaps as a result of heavy winter precipitation, and early Holocene expansion of the ITCZ. Drier conditions commenced by 5,700 cal yr BP, shown by declines in wetland pollen, and increases in high elevation steppe shrubs more common today (juniper, sage, and others). The local and regional impact of humans increased substantially after ca. 2700 years ago, with the regional loss of pine forest or woodland, increases in pollen and spore types associated with pasturing, and olive cultivation at lower elevations.

Anderson, R. S.; Jimenez-Moreno, G.

2010-12-01

123

Deglaciation in the High Andes - a Record from Laguna Piuray (Cusco, Peru)  

NASA Astrophysics Data System (ADS)

The Peruvian Andes lie in a crucial location for paleoclimate investigation. Fluctuating Pacific and Atlantic air masses compete for long-term dominance of the region, with the El-Nino Southern Oscillation (ENSO) system causing further variability. A laminated glacial/interglacial sediment sequence (6m) exposed around the shores of Laguna Piuray, near Cusco, offers not only the potential to reconstruct the climate history of the area but also to test for strength and frequency of the Atlantic monsoonal and Pacific ENSO influence. A suite of continuous cores was collected from deep trenches. The sedimentary record is characterized by postglacial diatom-rich chalk overlying organic-rich clayey chalk. Between these units are 3 distinct organic layers (80% TOC) deposited between 12-14 cal. kyr BP (14C). The base of the record is probably as old as 25kyrs (U/Th). We obtained a multi- proxy record of the section including continuous XRF scanning data of the entire sequence, and stable isotopes, XRF, XRD, TOC, biogenic opal, and carbonate analysis of discrete samples as well as a relative paleotemperature record from analyses of soil biomarkers. All the data profiles we obtained show a pronounced increase in temperature and decrease in precipitation at 13.8kyrs and are in good correlation with published regional Andean records using single proxies. Our results confirm that the Deglaciation Cold Reversal in central South America is not identical to the Younger Dryas event in the Northern Hemisphere.

Nederbragt, A.; Thurow, J.; Brumsack, H.; Lowe, J.; Pearce, R.; Ramsey, C.

2007-12-01

124

Eocene plant diversity at Laguna del Hunco and Río Pichileufú, Patagonia, Argentina.  

PubMed

The origins of South America's exceptional plant diversity are poorly known from the fossil record. We report on unbiased quantitative collections of fossil floras from Laguna del Hunco (LH) and Río Pichileufú (RP) in Patagonia, Argentina. These sites represent a frost-free humid biome in South American middle latitudes of the globally warm Eocene. At LH, from 4,303 identified specimens, we recognize 186 species of plant organs and 152 species of leaves. Adjusted for sample size, the LH flora is more diverse than comparable Eocene floras known from other continents. The RP flora shares several taxa with LH and appears to be as rich, although sampling is preliminary. The two floras were previously considered coeval. However, (40)Ar/(39)Ar dating of three ash-fall tuff beds in close stratigraphic association with the RP flora indicates an age of 47.46+/-0.05 Ma, 4.5 million years younger than LH, for which one tuff is reanalyzed here as 51.91+/-0.22 Ma. Thus, diverse floral associations in Patagonia evolved by the Eocene, possibly in response to global warming, and were persistent and areally extensive. This suggests extraordinary richness at low latitudes via the latitudinal diversity gradient, corroborated by published palynological data from the Eocene of Colombia. PMID:15937744

Wilf, Peter; Johnson, Kirk R; Cúneo, N Rubén; Smith, M Elliot; Singer, Bradley S; Gandolfo, Maria A

2005-06-01

125

Fault Scarp Offsets and Fault Population Analysis on Dione  

NASA Astrophysics Data System (ADS)

Cassini images of Dione show several fault zones cutting through the moon’s icy surface. We have measured the displacement and length of 271 faults, and estimated the strain occurring in 6 different fault zones. These measurements allow us to quantify the total amount of surface strain on Dione as well as constrain what processes might have caused these faults to form. Though we do not have detailed topography across fault scarps on Dione, we can use their projected size on the camera plane to estimate their heights, assuming a reasonable surface slope. Starting with high resolution images of Dione obtained by the Cassini ISS, we marked points at the top to the bottom of each fault scarp to measure the fault’s projected displacement and its orientation along strike. Line and sample information for the measurements were then processed through ISIS to derive latitude/longitude information and pixel dimensions. We then calculate the three dimensional orientation of a vector running from the bottom to the top of the fault scarp, assuming a 45 degree angle with respect to the surface, and project this vector onto the spacecraft camera plane. This projected vector gives us a correction factor to estimate the actual vertical displacement of the fault scarp. This process was repeated many times for each fault, to show variations of displacement along the length of the fault. To compare each fault to its neighbors and see how strain was accommodated across a population of faults, we divided the faults into fault zones, and created new coordinate systems oriented along the central axis of each fault zone. We could then quantify the amount of fault overlap and add the displacement of overlapping faults to estimate the amount of strain accommodated in each zone. Faults in the southern portion of Padua have a strain of 0.031(+/-) 0.0097, central Padua exhibits a strain of .032(+/-) 0.012, and faults in northern Padua have a strain of 0.025(+/-) 0.0080. The western faults of Eurotas have a strain of 0.031(+/-) 0.011, while the eastern faults have a strain of 0.037(+/-) 0.025. Lastly, Clusium has a strain of 0.10 (+/-) 0.029. We also calculated the ratio of maximum fault displacement vs. the length of the faults, and we found this ratio to be 0.019 when drawing a trend line through all the faults that were analyzed. D/L measurements performed on two faults on Europa using stereo topography showed a value of .021 (Nimmo and Schenk 2006), the only other icy satellite where this ratio has been measured. In contrast, faults on Earth has a D/L ratio of about .1 and Mars has a D/L Ratio of about .01 (Schultz et al. 2006).

Tarlow, S.; Collins, G. C.

2010-12-01

126

An empirical comparison of software fault tolerance and fault elimination  

NASA Technical Reports Server (NTRS)

Reliability is an important concern in the development of software for modern systems. Some researchers have hypothesized that particular fault-handling approaches or techniques are so effective that other approaches or techniques are superfluous. The authors have performed a study that compares two major approaches to the improvement of software, software fault elimination and software fault tolerance, by examination of the fault detection obtained by five techniques: run-time assertions, multi-version voting, functional testing augmented by structural testing, code reading by stepwise abstraction, and static data-flow analysis. This study has focused on characterizing the sets of faults detected by the techniques and on characterizing the relationships between these sets of faults. The results of the study show that none of the techniques studied is necessarily redundant to any combination of the others. Further results reveal strengths and weakness in the fault detection by the techniques studied and suggest directions for future research.

Shimeall, Timothy J.; Leveson, Nancy G.

1991-01-01

127

Fault zone structure of the Wildcat fault in Berkeley, California - Field survey and fault model test -  

Microsoft Academic Search

In order to develop hydrologic characterization technology of fault zones, it is desirable to clarify the relationship between the geologic structure and hydrologic properties of fault zones. To this end, we are performing surface-based geologic and trench investigations, geophysical surveys and borehole-based hydrologic investigations along the Wildcat fault in Berkeley,California to investigate the effect of fault zone structure on regional

K. Ueta; C. T. Onishi; K. Karasaki; S. Tanaka; T. Hamada; T. Sasaki; H. Ito; K. Tsukuda; K. Ichikawa; J. Goto; T. Moriya

2010-01-01

128

Reconstructing Fault History from Fault Rocks and Travertine Deposits, Rock Canyon Fault, Utah  

NASA Astrophysics Data System (ADS)

Central Utah lies along the eastern border of the Basin and Range Province. Within this region the Rock and Dry Canyon's graben structure is a block dropped down by oblique faults with an anomalous east-west orientation relative to other Basin and Range structures. Travertine is a rock composed of calcium carbonate that is commonly associated with faults, particularly active faults. The geometry and the macro/microstructures of travertine can provide a record of the evolution of the fault through time. The objectives of this study are to document the evidence of fault history contained in travertine formed along the Rock Canyon fault in order to test the hypothesis that this is a young, potentially active structure contributing to Basin and Range Province deformation. Polished rock slabs prepared from travertine samples collected along the mapped Rock Canyon fault show a wide range of textures, including columnar, radial/fibrous, banded, bedded, botryoidal, and brecciated travertine (broken, cemented fault rock) along with fibrous, brecciated, and blocky crystalline calcite. Angular clasts of layered travertine, deposited along the fault at an earlier stage, are contained within breccias documenting a subsequent slip event (or events). Therefore, initial observations on fault rock textures indicate that there were multiple slip episodes on the Rock Canyon fault. More detailed microscopic observations on thin sections prepared from the same samples will constrain the number and type of fracturing, fault slip, and vein precipitation events that occurred.

Main, J.; Wilson, T. J.

2011-12-01

129

Effect of surrounding fault on distributed fault of blind reverse fault in sedimentary basin - Uemachi Faults, Osaka Basin, Southwest Japan -  

NASA Astrophysics Data System (ADS)

Several large cities and metropolitan areas, such as Osaka and Kobe are located in the Osaka basin, which has been filled by the Pleistocene Osaka group and the later sediments. The basin is surrounded by E-W trending strike slip faults and N-S trending reverse faults. The N-S trending 42-km-long Uemachi faults traverse in the central part of the Osaka city. The various geological, geophysical surveys, such as seismic reflection, micro tremor, gravity surveys and deep boreholes, revealed the complex basement configuration along the Uemachi faults. The depth of the basement is shallow in the central part of the Osaka plain. The Uemachi faults are locates on the western side of the basement upland. In the central part of the Uemachi faults, the displacement decreases. The fault model of the Uemachi faults consists of the two parts, the north and south parts. The NE-SW trending branch faults, Suminoe and Sakuragawa flexures, are also recognized based on various surveys around the central part. Kusumoto et al. (2001) reported that surrounding faults enable to form the basement configuration without the Uemachi faults model based on a dislocation model. Inoue et al. (2011) performed various parameter studies for dislocation model and gravity changes based on simplified faults model, which were designed based on the distribution of the real faults. The model was consisted of 7 faults including the Uemachi faults. In this study, the Osaka-wan fault was considered for the dislocation model. The results show the basement configuration including NE-SW branch faults. The basement configuration differs from the subsurface structure derived from the investigation of abundance geotechnical borehole data around the central part of the Uemachi faults. The tectonic developing process including the erosion and sea level change are require to understanding the structure from the basement to the surface of the Uemachi Fault Zone. This research is partly funded by the Comprehensive Research on the Uemachi Fault Zone (in FY2010 and FY2011) by MEXT.

Inoue, N.

2012-12-01

130

Is Jiali Fault still an active fault in the late Pleistocene?  

Microsoft Academic Search

The Karakoram-Jiali Fault Zone (KJFZ) is the most important active structure system in the Tibetan Plateau. This zone consists of two major faults (i.e., Karakoram fault and Jiali fault) and other minor faults in between. The Karakoram fault strikes NW to SE in the western Tibet, while the Jiali fault roughly EW in the eastern Tibet, According to previous study,

L. Chung; Y. Chen; K. Lai; G. Yin; Z. Cao

2007-01-01

131

Abnormal fault-recovery characteristics of the fault-tolerant multiprocessor uncovered using a new fault-injection methodology  

NASA Technical Reports Server (NTRS)

An investigation was made in AIRLAB of the fault handling performance of the Fault Tolerant MultiProcessor (FTMP). Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once in every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles Byzantine or lying faults. Byzantine faults behave such that the faulted unit points to a working unit as the source of errors. The design's problems involve: (1) the design and interface between the simplex error detection hardware and the error processing software, (2) the functional capabilities of the FTMP system bus, and (3) the communication requirements of a multiprocessor architecture. These weak areas in the FTMP's design increase the probability that, for any hardware fault, a good line replacement unit (LRU) is mistakenly disabled by the fault management software.

Padilla, Peter A.

1991-01-01

132

Abnormal fault-recovery characteristics of the fault-tolerant multiprocessor uncovered using a new fault-injection methodology  

NASA Astrophysics Data System (ADS)

An investigation was made in AIRLAB of the fault handling performance of the Fault Tolerant MultiProcessor (FTMP). Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once in every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles Byzantine or lying faults. Byzantine faults behave such that the faulted unit points to a working unit as the source of errors. The design's problems involve: (1) the design and interface between the simplex error detection hardware and the error processing software, (2) the functional capabilities of the FTMP system bus, and (3) the communication requirements of a multiprocessor architecture. These weak areas in the FTMP's design increase the probability that, for any hardware fault, a good line replacement unit (LRU) is mistakenly disabled by the fault management software.

Padilla, Peter A.

1991-03-01

133

Managing Fault Management Development  

NASA Technical Reports Server (NTRS)

As the complexity of space missions grows, development of Fault Management (FM) capabilities is an increasingly common driver for significant cost overruns late in the development cycle. FM issues and the resulting cost overruns are rarely caused by a lack of technology, but rather by a lack of planning and emphasis by project management. A recent NASA FM Workshop brought together FM practitioners from a broad spectrum of institutions, mission types, and functional roles to identify the drivers underlying FM overruns and recommend solutions. They identified a number of areas in which increased program and project management focus can be used to control FM development cost growth. These include up-front planning for FM as a distinct engineering discipline; managing different, conflicting, and changing institutional goals and risk postures; ensuring the necessary resources for a disciplined, coordinated approach to end-to-end fault management engineering; and monitoring FM coordination across all mission systems.

McDougal, John M.

2010-01-01

134

Randomness fault detection system  

NASA Technical Reports Server (NTRS)

A method and apparatus are provided for detecting a fault on a power line carrying a line parameter such as a load current. The apparatus monitors and analyzes the load current to obtain an energy value. The energy value is compared to a threshold value stored in a buffer. If the energy value is greater than the threshold value a counter is incremented. If the energy value is greater than a high value threshold or less than a low value threshold then a second counter is incremented. If the difference between two subsequent energy values is greater than a constant then a third counter is incremented. A fault signal is issued if the counter is greater than a counter limit value and either the second counter is greater than a second limit value or the third counter is greater than a third limit value.

Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

1996-01-01

135

Fault tolerant mechanism design  

Microsoft Academic Search

Abstract We introduce the notion of fault tolerant mechanism design, which ex- tends the standard game,theoretic framework,of mechanism,design to allow for uncertainty about execution. Specically, we dene the problem of task allocation in which the private information of the agents is not only their costs of attempting the tasks but also their probabilities of failure. For several dif- ferent instances

Ryan Porter; Amir Ronen; Yoav Shoham; Moshe Tennenholtz

2008-01-01

136

Dynamic Fault Detection Chassis  

Microsoft Academic Search

The high frequency switching megawatt-class High Voltage Converter Modulator (HVCM) developed by Los Alamos National Laboratory for the Oak Ridge National Laboratory's Spallation Neutron Source (SNS) is now in operation. One of the major problems with the modulator systems is shoot-thru conditions that can occur in a IGBTs H-bridge topology resulting in large fault currents and device failure in a

Mize; Jeffery J

2007-01-01

137

Practical quantum fault tolerance  

NASA Astrophysics Data System (ADS)

The standard approach to quantum fault tolerance is to calculate error thresholds on basic gates in the limit of arbitrarily many concatenation levels. In contrast this paper takes the number of qubits and the target implementation accuracy as given, and provides a framework for engineering the constrained quantum system to the required tolerance. The approach requires solving the full dynamics of the quantum system for an arbitrary admixture (biased or unbiased) of Pauli errors. The inaccuracy between ideal and implemented quantum systems is captured by the supremum of the Schatten k-norm of the difference between the ideal and implemented density matrices taken over all density matrices. This is a more complete analysis than the standard approach, where an intricate combination of worst case assumptions and combinatorial analysis is used to analyze the special case of equiprobable errors. Conditions for fault tolerance are now expressed in terms of error regions rather than a single number (the standard error threshold). In the important special case of a stochastic noise model and a single logical qubit, an optimization over all 2×2 density matrices is required to obtain the full dynamics. The complexity of this calculation is greatly simplified through reduction to an optimization over only three projectors. Error regions are calculated for the standard 5- and 7-qubit codes. Knowledge of the full dynamics makes it possible to design sophisticated concatenation strategies that go beyond repeatedly using the same code, and these strategies can achieve target fault tolerance thresholds with fewer qubits.

Gilbert, G.; Weinstein, Y. S.; Aggarwal, V.; Calderbank, A. R.

2009-05-01

138

The South Marmara Fault  

NASA Astrophysics Data System (ADS)

We use about 800 km of multichannel exploration seismic reflection profiles of the seventies as well as the results of three drill holes that penetrated the sedimentary cover down to the Upper Cretaceous basement to describe a continuous gently curvilinear, south-concave zone of deformation about 10 km wide that extended over the whole southern shelf of the Sea of Marmara from the Gulf of Gemlik to the Dardanelles Straits in Lower Pliocene time, about 4 Ma. We call this zone of deformation the South Marmara Fault (SMF) system and propose that the SMF was then a branch of the dextral North Anatolian Fault. This branch passed to the north of the Marmara Island Eocene block and thus had a south-facing concavity. This curvature resulted in a significant component of shortening in the western part of the fault. The SMF was deactivated at the end of Lower Pliocene, about 3.5 Ma, except for its easternmost branch between the Gulf of Gemlik and ?mral? Island where about 5 mm/year of dextral motion is still occurring today.

Le Pichon, Xavier; ?mren, Caner; Rangin, Claude; ?engör, A. M. Celâl; Siyako, Muzaffer

2014-01-01

139

Seismic Hazard and Fault Length  

NASA Astrophysics Data System (ADS)

If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern California. In this study, we found that mapped fault length and rupture length are often unequal, and in several cases rupture broke beyond the previously mapped fault traces. To expand the geologic definition of fault length we outlined several guidelines: 1) if a fault truncates at young Quaternary alluvium, the fault line should be inferred underneath the younger sediments 2) faults striking within 45° of one another should be treated as a continuous fault line and 3) a step-over can link together faults at least 5 km apart. These definitions were applied to fault lines in Southern California. For example, many of the along-strike faults lines in the Mojave Desert are treated as a single fault trending from the Pinto Mountain to the Garlock fault. In addition, the Rose Canyon and Newport-Inglewood faults are treated as a single fault line. We used these more generous fault lengths, and the Wells and Coppersmith regression, to estimate the maximum magnitude (mx) for the major faults in southern California. Then we compared our mx values with those proposed by CALTRANS, and those assumed in the 2002 USGS/CGS hazard model. To calculate the planning magnitude mp we assumed a truncated Gutenberg-Richter magnitude distribution with parameters a, b, and mx. We fixed b and solved for the a-value in terms of mx, b, and the tectonic moment rate. For many faults mp is relatively insensitive to mx and typically falls off at higher magnitudes because the a-value decreases with increasing mx when the moment rate is constrained. Furthermore, we find that by increasing mx the cumulative earthquake rate actually decreases for smaller magnitude (5 and 6) events. This suggests that fewer magnitude 5 and 6 earthquakes are required to balance the moment budget if larger, but highly infrequent, earthquakes are allowed to occur.

Black, N. M.; Jackson, D. D.; Mualchin, L.

2005-12-01

140

Origin and evolution of the Laguna Potrok Aike maar (Southern Patagonia, Argentina) as revealed by seismic data  

NASA Astrophysics Data System (ADS)

Seismic reflection and refraction data provide insights into the sedimentary infill and the underlying volcanic structure of Laguna Potrok Aike, a maar lake situated in the Pali Aike Volcanic Field, Southern Patagonia. The lake has a diameter of ~3.5 km, a maximum water depth of ~100 m and a presumed age of ~770 ka. Its sedimentary regime is influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Multiproxy environmental reconstructions of the last 16 ka document that this terminal lake is highly sensitive to climate change. Laguna Potrok Aike has recently become a major focus of the International Continental Scientific Drilling Program and was drilled down to 100 m below lake floor in late 2008 within the PASADO project. The sediments are likely to contain a continental record spanning the last ca. 80 kyrs unique in the South American realm. Seismic reflection data show relatively undisturbed, stratified lacustrine sediments at least in the upper ~100 m of the sedimentary infill but are obscured possibly by gas and/or coarser material in larger areas. A model calculated from seismic refraction data reveals a funnel-shaped structure embedded in the sandstone rocks of the surrounding Santa Cruz Formation. This funnel structure is filled by lacustrine sediments of up to 370 m in thickness. These can be separated into two distinct subunits with low acoustic velocities of 1500-1800 m s-1 in the upper subunit pointing at unconsolidated lacustrine muds, and enhanced velocities of 2000-2350 m s-1 in the lower subunit. Below these lacustrine sediments, a unit of probably volcanoclastic origin is observed (>2400 m s-1). This sedimentary succession is well comparable to other well-studied sequences (e.g. Messel and Baruth maars, Germany), confirming phreatomagmatic maar explosions as the origin of Laguna Potrok Aike.

Gebhardt, C.; de Batist, M. A.; Niessen, F.; Anselmetti, F.; Ariztegui, D.; Haberzettl, T.; Ohlendorf, C.; Zolitschka, B.

2009-12-01

141

Microbiological quality of chicken- and pork-based street-vended foods from Taichung, Taiwan, and Laguna, Philippines.  

PubMed

The microbiological quality of chicken- and pork-based street-food samples from Taichung, Taiwan's night markets (50) and Laguna, Philippines' public places (69) was evaluated in comparison to a microbiological guideline for ready-to-eat foods. Different bacterial contamination patterns were observed between 'hot-grilled' and 'cold cooked/fried' food types from the two sampling locations with 'hot grilled' foods generally showing better microbiological quality. Several samples were found to be unsatisfactory due to high levels of aerobic plate count, coliform, Escherichia coli, and Staphylococcus aureus. The highest counts obtained were 8.2 log cfu g?¹, 5.4 log cfu g?¹, 4.4 log cfu g?¹, and 3.9 log cfu g?¹, respectively, suggesting poor food hygiene practices and poor sanitation. Salmonella was found in 8% and 7% of Taichung and Laguna samples, respectively, which made the samples potentially hazardous. None of the samples was found to be positive for Listeria monocytogenes and E. coli O157, but Bacillus cereus was detected at the unsatisfactory level of 4 log cfu g?¹ in one Laguna sample. Antimicrobial resistance was observed for Salmonella, E. coli, and S. aureus isolates. Food preparation, cooking, and food handling practices were considered to be contributors to the unacceptable microbiological quality of the street foods. Hence, providing training on food hygiene for the street vendors should result in the improvement of the microbiological quality of street foods. The data obtained in this study can be used as input to microbial risk assessments and in identifying science-based interventions to control the hazards. PMID:23764220

Manguiat, Lydia S; Fang, Tony J

2013-10-01

142

The Development of a Restless Rhyolite Magma Chamber at Laguna del Maule, Chile  

NASA Astrophysics Data System (ADS)

The Laguna del Maule (LdM) volcanic field is a site of rapid crustal deformation at rates in excess of 200 mm/yr since 2007. The uplift is centered in the 16 km diameter LdM lake basin, which is ringed by 21 rhyolite domes and coulees erupted since the last glacial retreat. The lack of previously common andesite and dacite eruptions since 19 ka and coherent major and trace element variation throughout post-glacial time suggests the presence of a large silicic magma body beneath the LdM basin. Assimilation-fractional crystallization modeling predicts the rhyolites evolved at 5 km depth by 73% fractionation of a basaltic parent and modest assimilation of granodiorite accounting for up to 20% of the highest silica rhyolite. AFC processes dominate the evolution from basalt, however the differentiation of the silicic magma is complicated by liquid extraction from crystal mush, remelting of cumulate by intruding basalt, and trace element diffusion. Two-oxide thermometry indicates a relatively hot, oxidized system with eruptive temperatures ranging from 760 - 850° C and fO2 at QFM+2. Pilot ion microprobe 238U-230Th dating of zircon rims suggests the shallow LdM magma system was assembled over a period of 100-200 kyr. 40Ar/39Ar geochronology and field relationships reveal the post-glacial silicic volcanism occurred in two phases. Phase 1 began approximately coincident with deglaciation at 25 ka with the eruption of the rhyolite East of Presa Laguna del Maule. Over the next 6 ky, 6 small rhyodacite domes, a larger rhyodacite flow, and 4 andesite flows erupted in the NW basin and two silicic domes 12 km to the SE. Phase 1 culminates with the eruption of the Espejos rhyolite near the N shore of the lake at 19 ka. The locus of volcanism then migrates SE and phase 2 begins at ~10 ka with the eruption of the Cari Launa rhyolite and the early flows of the Barrancas complex. This period is more voluminous, erupting 4.8 km3 compared to 1.7 km3 during phase 1. Phase 2 produced lower silica rhyolite (72-74%) than the majority erupted during phase 1 (75-76%) but a smaller range of compositions overall as andesite and rhyodacite eruptions become rare and peripheral. The two phases are also distinguished by a small, but consistent, shift in REE contents. Phase 1 is marked by lower REE contents, but higher Ce/Sm ratios. The chemical trends are temporally, rather than spatially, correlated reflecting the evolution of an integrated magma body rather than local vagaries in magmatic process. Early eruptions in both phases 1 and 2 are characterized by elevated two-oxide temperatures, the presence of trace pyrrhotite, and Ta contents 2-3 times greater than subsequent eruptions, an enrichment of similar magnitude to that observed in the early Bishop Tuff. The intrusion of basalt to the base of the magma chamber could provide a source of heat and volatiles catalyzing the crystallization of Fe-sulfide and roofward diffusion of Ta. Such events have been followed by periods of heightened volcanic activity and produced an increasing rate of silicic magma generation. If the current unrest is indicative of basaltic intrusion, it could foreshadow continuing silicic volcanism at LdM, potentially leading to a catastrophic caldera forming eruption.

Andersen, N.; Singer, B. S.; Jicha, B. R.; Fierstein, J.; Vazquez, J. A.

2013-12-01

143

Postglacial history of alpine vegetation, fire, and climate from Laguna de Río Seco, Sierra Nevada, southern Spain  

NASA Astrophysics Data System (ADS)

The Sierra Nevada of southern Spain is a landscape with a rich biological and cultural heritage. The range was extensively glaciated during the late Pleistocene. However, the postglacial paleoecologic history of the highest range in southern Europe is nearly completely unknown. Here we use sediments from a small lake above present treeline - Laguna de Río Seco at 3020 m elevation - in a paleoecological study documenting over 11,500 calendar years of vegetation, fire and climate change, addressing ecological and paleoclimatic issues unique to this area through comparison with regional paleoecological sequences. The early record is dominated by Pinus pollen, with Betula, deciduous Quercus, and grasses, with an understory of shrubs. It is unlikely that pine trees grew around the lake, and fire was relatively unimportant at this site during this period. Aquatic microfossils indicate that the wettest conditions and highest lake levels at Laguna de Río Seco occurred before 7800 cal yr BP. This is in contrast to lower elevation sites, where wettest conditions occurred after ca 7800. Greater differences in early Holocene seasonal insolation may have translated to greater snowpack and subsequently higher lake levels at higher elevations, but not necessarily at lower elevations, where higher evaporation rates prevailed. With declining seasonality after ca 8000 cal yr BP, but continuing summer precipitation, lake levels at the highest elevation site remained high, but lake levels at lower elevation sites increased as evaporation rates declined. Drier conditions commenced regionally after ca 5700 cal yr BP, shown at Laguna de Río Seco by declines in wetland pollen, and increases in high elevation steppe shrubs common today ( Juniperus, Artemisia, and others). The disappearance or decline of mesophytes, such as Betula from ca 4000 cal yr BP is part of a regional depletion in Mediterranean Spain and elsewhere in Europe from the mid to late Holocene. On the other hand, Castanea sativa increased in Laguna de Río Seco record after ca 4000 cal yr BP, and especially in post-Roman times, probably due to arboriculture. Though not as important at high than at low elevations, fire occurrence was elevated, particularly after ca 3700 years ago, in response to regional human population expansion. The local and regional impact of humans increased substantially after ca 2700 years ago, with the loss of Pinus forest within the mountain range, increases in evidence of pasturing herbivores around the lake, and Olea cultivation at lower elevations. Though human impact was not as extensive at high elevation as at lower elevation sites in southern Iberia, this record confirms that even remote sites were not free of direct human influence during the Holocene.

Anderson, R. S.; Jiménez-Moreno, G.; Carrión, J. S.; Pérez-Martínez, C.

2011-06-01

144

Dynamics of fault interaction - Parallel strike-slip faults  

Microsoft Academic Search

We use a 2D finite difference computer program to study the effect of fault steps on dynamic ruptures. Our results indicate that a strike-slip earthquake is unlikely to jump a fault step wider than 5 km, in correlation with field observations of moderate to great-sized earthquakes. We also find that dynamically propagating ruptures can jump both compressional and dilational fault

Ruth A. Harris; Steven M. Day

1993-01-01

145

Impact of solar radiation on bacterioplankton in Laguna Vilama, a hypersaline Andean lake (4650 m)  

NASA Astrophysics Data System (ADS)

Laguna Vilama is a hypersaline Lake located at 4660 m altitude in the northwest of Argentina high up in the Andean Puna. The impact of ultraviolet (UV) radiation on bacterioplankton was studied by collecting samples at different times of the day. Molecular analysis (DGGE) showed that the bacterioplankton community is characterized by Gamma-proteobacteria (Halomonas sp., Marinobacter sp.), Alpha-proteobacteria (Roseobacter sp.), HGC (Agrococcus jenensis and an uncultured bacterium), and CFB (uncultured Bacteroidetes). During the day, minor modifications in bacterial diversity such as intensification of Bacteroidetes' signal and an emergence of Gamma-proteobacteria (Marinobacter flavimaris) were observed after solar exposure. DNA damage, measured as an accumulation of Cyclobutane Pyrimidine Dimers (CPDs), in bacterioplankton and naked DNA increased from 100 CPDs MB-1 at 1200 local time (LT) to 300 CPDs MB-1 at 1600 LT, and from 80 CPDs MB-1 at 1200 LT to 640 CPDs MB-1 at 1600 LT, respectively. In addition, pure cultures of Pseudomonas sp. V1 and Brachybacterium sp. V5, two bacteria previously isolated from this environment, were exposed simultaneously with the community, and viability of both strains diminished after solar exposure. No CPD accumulation was observed in either of the exposed cultures, but an increase in mutagenesis was detected in V5. Of both strains only Brachybacterium sp. V5 showed CPD accumulation in naked DNA. These results suggest that the bacterioplankton community is well adapted to this highly solar irradiated environment showing little accumulation of CPDs and few changes in the community composition. They also demonstrate that these microorganisms contain efficient mechanisms against UV damage.

FaríAs, MaríA. Eugenia; FernáNdez-Zenoff, Verónica; Flores, Regina; OrdóñEz, Omar; EstéVez, Cristina

2009-06-01

146

Rickettsia bellii, Rickettsia amblyommii, and Laguna Negra hantavirus in an Indian reserve in the Brazilian Amazon  

PubMed Central

Background The purpose of this study was to identify the presence of rickettsia and hantavirus in wild rodents and arthropods in response to an outbreak of acute unidentified febrile illness among Indians in the Halataikwa Indian Reserve, northwest of the Mato Grosso state, in the Brazilian Amazon. Where previously surveillance data showed serologic evidence of rickettsia and hantavirus human infection. Methods The arthropods were collected from the healthy Indian population and by flagging vegetation in grassland or woodland along the peridomestic environment of the Indian reserve. Wild rodents were live-trapped in an area bordering the reserve limits, due the impossibility of capturing wild animals in the Indian reserve. The wild rodents were identified based on external and cranial morphology and karyotype. DNA was extracted from spleen or liver samples of rodents and from invertebrate (tick and louse) pools, and the molecular characterization of the rickettsia was through PCR and DNA sequencing of fragments of two rickettsial genes (gltA and ompA). In relation to hantavirus, rodent serum samples were serologically screened by IgG ELISA using the Araraquara-N antigen and total RNA was extracted from lung samples of IgG-positive rodents. The amplification of the complete S segment was performed. Results A total of 153 wild rodents, 121 louse, and 36 tick specimens were collected in 2010. Laguna Negra hantavirus was identified in Calomys callidus rodents and Rickettsia bellii, Rickettsia amblyommii were identified in Amblyomma cajennense ticks. Conclusions Zoonotic diseases such as HCPS and spotted fever rickettsiosis are a public health threat and should be considered in outbreaks and acute febrile illnesses among Indian populations. The presence of the genome of rickettsias and hantavirus in animals in this Indian reserve reinforces the need to include these infectious agents in outbreak investigations of febrile cases in Indian populations.

2014-01-01

147

Hydrocarbon concentrations in the American oyster, Crassostrea virginica, in Laguna de Terminos, Campeche, Mexico  

SciTech Connect

Laguna de Terminos is a 2,500 km{sup 2} coastal lagoon in the southern Gulf of Mexico, located between 18{degrees} 20` and 19{degrees} 00` N, and 91{degrees} 00` and 92{degrees} 20` W (Figure 1). It is a shallow lagoon, with a mean depth of 3.5 m and connected to the Gulf of Mexico through two permanent inlets, Puerto Real to the east and Carmen to the west. Several rivers, most of them from the Grijalva-Usumacinta basin (the largest in Mexico and second largest in the Gulf of Mexico), drain into the lagoon with a mean annual discharge of 6 X 10{sup 9} m{sup 3}/year. This lagoon has been studied systematically, and is probably one of the best known in Mexico. An excellent overview of this lagoon can be found in Yanez-Arancibia and Day. The continental shelf north of Terminos, the Campeche Bank, is the main oil-producing zone in Mexico with a production of about 2 X 10{sup 6} barrels/day. It is also the main shrimp producer in the southern Gulf, with a mean annual catch of 18,000 tonnes/year, which represents 38 to 50% of the national catch in the Gulf of Mexico. The economic importance of this region, along with its extremely high biodiversity, both in terms of species and habitats, has prompted the Mexican government to study the creation of a wildlife refuge around Terminos. Thus, it is very important to know the current levels of pollutants in this area, as a contribution to the management plan of the proposed protected area. This paper looks at hydrocarbon concentrations in oyster tissue. 14 refs., 3 figs., 21 tabs.

Gold-Bouchot, G.; Norena-Barroso, E.; Zapata-Perez, O. [Unidad Merida, Yucatan (Mexico)

1995-02-01

148

Holocene History of the Chocó Rain Forest from Laguna Piusbi, Southern Pacific Lowlands of Colombia  

NASA Astrophysics Data System (ADS)

A high-resolution pollen record from a 5-m-long sediment core from the closed-lake basin Laguna Piusbi in the southern Colombian Pacific lowlands of Chocó, dated by 11 AMS 14C dates that range from ca. 7670 to 220 14C yr B.P., represents the first Holocene record from the Chocó rain forest area. The interval between 7600 and 6100 14C yr B.P. (500-265 cm), composed of sandy clays that accumulated during the initial phase of lake formation, is almost barren of pollen. Fungal spores and the presence of herbs and disturbance taxa suggest the basin was at least temporarily inundated and the vegetation was open. The closed lake basin might have formed during an earthquake, probably about 4400 14C yr B.P. From the interval of about 6000 14C yr B.P. onwards, 200 different pollen and spore types were identified in the core, illustrating a diverse floristic composition of the local rain forest. Main taxa are Moraceae/Urticaceae, Cecropia,Melastomataceae/Combretaceae, Acalypha, Alchornea,Fabaceae, Mimosa, Piper, Protium, Sloanea, Euterpe/Geonoma, Socratea,and Wettinia.Little change took place during that time interval. Compared to the pollen records from the rain forests of the Colombian Amazon basin and adjacent savannas, the Chocó rain forest ecosystem has been very stable during the late Holocene. Paleoindians probably lived there at least since 3460 14C yr B.P. Evidence of agricultural activity, shown by cultivation of Zea maissurrounding the lake, spans the last 1710 yr. Past and present very moist climate and little human influence are important factors in maintaining the stable ecosystem and high biodiversity of the Chocó rain forest.

Behling, Hermann; Hooghiemstra, Henry; Negret, Alvaro José

1998-11-01

149

Fault management for data systems  

NASA Technical Reports Server (NTRS)

Issues related to automating the process of fault management (fault diagnosis and response) for data management systems are considered. Substantial benefits are to be gained by successful automation of this process, particularly for large, complex systems. The use of graph-based models to develop a computer assisted fault management system is advocated. The general problem is described and the motivation behind choosing graph-based models over other approaches for developing fault diagnosis computer programs is outlined. Some existing work in the area of graph-based fault diagnosis is reviewed, and a new fault management method which was developed from existing methods is offered. Our method is applied to an automatic telescope system intended as a prototype for future lunar telescope programs. Finally, an application of our method to general data management systems is described.

Boyd, Mark A.; Iverson, David L.; Patterson-Hine, F. Ann

1993-01-01

150

Software Evolution and the Fault Process  

NASA Technical Reports Server (NTRS)

In developing a software system, we would like to estimate the way in which the fault content changes during its development, as well determine the locations having the highest concentration of faults. In the phases prior to test, however, there may be very little direct information regarding the number and location of faults. This lack of direct information requires developing a fault surrogate from which the number of faults and their location can be estimated. We develop a fault surrogate based on changes in the fault index, a synthetic measure which has been successfully used as a fault surrogate in previous work. We show that changes in the fault index can be used to estimate the rates at which faults are inserted into a system between successive revisions. We can then continuously monitor the total number of faults inserted into a system, the residual fault content, and identify those portions of a system requiring the application of additional fault detection and removal resources.

Nikora, Allen P.; Munson, John C.

1999-01-01

151

Fault trees and sequence dependencies  

Microsoft Academic Search

One of the frequency cited shortcomings of fault-tree models, their inability to model so-called sequence dependencies, is discussed. Several sources of such sequence dependencies are discussed, and new fault-tree gates to capture this behavior are defined. These complex behaviors can be included in present fault-tree models because they utilize a Markov solution. The utility of the new gates is demonstrated

Joanne Bechta Dugan; Salvatore J. Bavuso; Mark A. Boyd

1990-01-01

152

Compositional Temporal Fault Tree Analysis  

Microsoft Academic Search

HiP-HOPS (Hierarchically-Performed Hazard Origin and Propaga- tion Studies) is a recent technique that partly automates Fault Tree Analysis (FTA) by constructing fault trees from system topologies annotated with component-level failure specifications. HiP-HOPS has hitherto created only classical combinatorial fault trees that fail to capture the often significant temporal ordering of failure events. In this paper, we propose temporal extensions to

Martin Walker; Leonardo Bottaci; Yiannis Papadopoulos

2007-01-01

153

Handling Software Faults with Redundancy  

Microsoft Academic Search

Software engineering methods can increase the dependability of software systems, and yet some faults escape even the most\\u000a rigorous and methodical development process. Therefore, to guarantee high levels of reliability in the presence of faults,\\u000a software systems must be designed to reduce the impact of the failures caused by such faults, for example by deploying techniques\\u000a to detect and compensate

Antonio Carzaniga; Alessandra Gorla; Mauro Pezzè

2008-01-01

154

Software Fault Tolerance in the Application Layer  

Microsoft Academic Search

By software fault tolerance in the application layer, we mean a set of application level software components to detect and recover from faults that are not handled in the hardware or operating system layers of a computer system. We consider those faults that cause an application process to crash or hang; they include application software faults as well as faults

Yennun Huang

1995-01-01

155

Multiple Fault Diagnosis in Combinational Networks.  

National Technical Information Service (NTIS)

A new concept, the prime fault, is introduced for the study of multiple fault diagnosis in combinational logic networks. It is shown that every multiple fault in a network can be represented by a functionally equivalent fault with prime faults as its only...

C. W. Y. Cha

1974-01-01

156

Experimental Fault Reactivation on Favourably and Unfavourably Oriented Faults  

NASA Astrophysics Data System (ADS)

In this study, we introduce work which aims assess the loading of faults to failure under different stress regimes in a triaxial deformation apparatus. We explore experimentally the reshear of an existing fault in various orientations for particular values of (?1 - ?3) and ?3' for contrasting loading systems - load-strengthening (equivalent to a thrust fault) with ?1' increasing at constant ?3', versus load-weakening (equivalent to a normal fault) with reducing ?3' under constant ?1'. Experiments are conducted on sawcut granite samples with fault angles at a variety of orientations relative to ?1 , ranging from an optimal orientation for reactivation to lockup angles where new faults are formed in preference to reactivating the existing sawcut orientation. Prefailure and postfailure behaviour is compared in terms of damage zone development via monitoring variations in ultrasonic velocity and acoustic emission behaviour. For example, damage surrounding unfavourably oriented faults is significantly higher than that seen around favourably orientated faults due to greater maximum stresses attained prior to unstable slip, which is reflected by the increased acoustic emission activity leading up to failure. In addition, we also experimentally explore the reshear of natural pseudotachylytes (PSTs) from two different fault zones; the Gole Larghe Fault, Adamello, Italy in which the PSTs are in relatively isotropic Tonalite (at lab sample scale) and the Alpine Fault, New Zealand in which the PSTs are in highly anisotropic foliated shist. We test whether PSTs will reshear in both rock types under the right conditions, or whether new fractures in the wall rock will form in preference to reactivating the PST (PST shear strength is higher than that of the host rock). Are PSTs representative of one slip event?

Mitchell, T. M.; Sibson, R. H.; Renner, J.; Toy, V. G.; di Toro, G.; Smith, S. A.

2010-12-01

157

Fault trees and sequence dependencies  

NASA Technical Reports Server (NTRS)

One of the frequently cited shortcomings of fault-tree models, their inability to model so-called sequence dependencies, is discussed. Several sources of such sequence dependencies are discussed, and new fault-tree gates to capture this behavior are defined. These complex behaviors can be included in present fault-tree models because they utilize a Markov solution. The utility of the new gates is demonstrated by presenting several models of the fault-tolerant parallel processor, which include both hot and cold spares.

Dugan, Joanne Bechta; Boyd, Mark A.; Bavuso, Salvatore J.

1990-01-01

158

Fault-tolerant processing system  

NASA Technical Reports Server (NTRS)

A fault-tolerant, fiber optic interconnect, or backplane, which serves as a via for data transfer between modules. Fault tolerance algorithms are embedded in the backplane by dividing the backplane into a read bus and a write bus and placing a redundancy management unit (RMU) between the read bus and the write bus so that all data transmitted by the write bus is subjected to the fault tolerance algorithms before the data is passed for distribution to the read bus. The RMU provides both backplane control and fault tolerance.

Palumbo, Daniel L. (Inventor)

1996-01-01

159

Perspective View, Garlock Fault  

NASA Technical Reports Server (NTRS)

California's Garlock Fault, marking the northwestern boundary of the Mojave Desert, lies at the foot of the mountains, running from the lower right to the top center of this image, which was created with data from NASA's shuttle Radar Topography Mission (SRTM), flown in February 2000. The data will be used by geologists studying fault dynamics and landforms resulting from active tectonics. These mountains are the southern end of the Sierra Nevada and the prominent canyon emerging at the lower right is Lone Tree canyon. In the distance, the San Gabriel Mountains cut across from the leftside of the image. At their base lies the San Andreas Fault which meets the Garlock Fault near the left edge at Tejon Pass. The dark linear feature running from lower right to upper left is State Highway 14 leading from the town of Mojave in the distance to Inyokern and the Owens Valley in the north. The lighter parallel lines are dirt roads related to power lines and the Los Angeles Aqueduct which run along the base of the mountains.

This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

Size: Varies in a perspective view Location: 35.25 deg. North lat., 118.05 deg. West lon. Orientation: Looking southwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

2000-01-01

160

Computer system isolates faults  

SciTech Connect

Maintaining transaction processing systems in continuous operation, a minicomputer system made by tolerant systems detects and isolates faults, then transfers work loads to the appropriate backup resource. An eternity system is actually 1 to 15 computer systems, called system building blocks, interconnected by a communication network. Modularity is provided by tolerant's flexible architecture technique. This allows a user to expand system capacity with nondedicated computers which can be assigned to tasks such as increasing processing power, user accessibility and database size as dictated by needs. The loosely-coupled nature of the system increases reliability.

Hall, D.E.

1983-11-01

161

It's All Their Fault?  

PubMed

Many students fail our introductory science courses and give up on science altogether. How much of this is their fault is debatable. But what is not debatable is that we can improve the situation by using active learning methods. Many faculty claim critical thinking is their highest priority. Their teaching seldom reflects this. They emphasize facts and lecture without context. Most of our students are not going to be scientists, but they are going to be citizens and need to be able to spot inaccuracies when they appear in the media. Case-based and Problem-based Teaching are proven ways to achieve this goal. PMID:23653695

Herreid, Clyde Freeman

2010-01-01

162

It's All Their Fault?  

PubMed Central

Many students fail our introductory science courses and give up on science altogether. How much of this is their fault is debatable. But what is not debatable is that we can improve the situation by using active learning methods. Many faculty claim critical thinking is their highest priority. Their teaching seldom reflects this. They emphasize facts and lecture without context. Most of our students are not going to be scientists, but they are going to be citizens and need to be able to spot inaccuracies when they appear in the media. Case-based and Problem-based Teaching are proven ways to achieve this goal.

Herreid, Clyde Freeman

2010-01-01

163

Fault current limiter  

SciTech Connect

A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

Darmann, Francis Anthony

2013-10-08

164

Dynamics of earthquake faults  

SciTech Connect

The authors present an overview of ongoing studies of the rich dynamical behavior of the uniform, deterministic Burridge-Knopoff model of an earthquake fault, discussing the model's behavior in the context of current seismology. The topics considered include: (1) basic properties of the model, such as the distinction between small and large events and the magnitude vs frequency distribution; (2) dynamics of individual events, including dynamical selection of rupture propagation speeds; (3) generalizations of the model to more realistic, higher-dimensional models; and (4) studies of predictability, in which artificial catalogs generated by the model are used to test and determine the limitations of pattern recognition algorithms used in seismology.

Carlson, J.M. (Department of Physics and Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)); Langer, J.S. (Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)); Shaw, B.E. (Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States) Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964 (United States))

1994-04-01

165

The load balance on the fault ring based fault-tolerant routing scheme in Tori  

Microsoft Academic Search

In the network of tori with faults, many fault-tolerant routing schemes have been proposed based on the fault models. Although these schemes enable the packets to bypass the fault regions without causing any deadlock in the network, they have the common shortcoming. Since all blocked packets would be misrouted on the fault ring, the fault ring would undertake heavier traffic

Lingfu Xie; Du Xu; Shizhong Xu

2009-01-01

166

A complete algorithm to fault calculation due to simultaneous faults. \\  

Microsoft Academic Search

This paper discusses the great variety of fault types that can arise on a power system. The most important techniques of this paper is the consideration of unequal magnitudes of source EMF and with different phase angles to show their effect on fault analysis and protection of the power system. Furthermore, an algorithm developed for the calculation of simultaneous power

Fathy M. Abouelenin

2002-01-01

167

Fault Branching and Rupture Directivity  

NASA Astrophysics Data System (ADS)

Can the rupture directivity of past earthquakes be inferred from fault geometry? Nakata et al. [J. Geogr., 1998] propose to relate the observed surface branching of fault systems with directivity. Their work assumes that all branches are through acute angles in the direction of rupture propagation. However, in some observed cases rupture paths seem to branch through highly obtuse angles, as if to propagate ``backwards". Field examples of that are as follows: (1) Landers 1992. When crossing from the Johnson Valley to the Homestead Valley (HV) fault via the Kickapoo (Kp) fault, the rupture from Kp progressed not just forward onto the northern stretch of the HV fault, but also backwards, i.e., SSE along the HV [Sowers et al., 1994, Spotila and Sieh, 1995, Zachariasen and Sieh, 1995, Rockwell et al., 2000]. Measurements of surface slip along that backward branch, a prominent feature of 4 km length, show right-lateral slip, decreasing towards the SSE. (2) At a similar crossing from the HV to the Emerson (Em) fault, the rupture progressed backwards along different SSE splays of the Em fault [Zachariasen and Sieh, 1995]. (3). In crossing from the Em to Camp Rock (CR) fault, again, rupture went SSE on the CR fault. (4). Hector Mine 1999. The rupture originated on a buried fault without surface trace [Li et al., 2002; Hauksson et al., 2002] and progressed bilaterally south and north. In the south it met the Lavic Lake (LL) fault and progressed south on it, but also progressed backward, i.e. NNW, along the northern stretch of the LL fault. The angle between the buried fault and the northern LL fault is around -160o, and that NNW stretch extends around 15 km. The field examples with highly obtuse branch angles suggest that there may be no simple correlation between fault geometry and rupture directivity. We propose that an important distinction is whether those obtuse branches actually involved a rupture path which directly turned through the obtuse angle (while continuing also on the main fault), or rather involved arrest by a barrier on the original fault and jumping [Harris and Day, JGR, 1993] to a neighboring fault on which rupture propagated bilaterally to form what appears as a backward-branched structure. Our studies [Poliakov et al., JGR in press, 2002; Kame et al, EOS, 2002] of stress fields around a dynamically moving mode II crack tip show a clear tendency to branch from the straight path at high rupture speeds, but the stress fields never allow the rupture path to directly turn through highly obtuse angles, and hence that mechanism is unlikely. In contrast, study of fault maps in the vicinity of the Kp to HV fault transition [Sowers et al., 1994], discussed as case (1) above, strongly suggest that the large-angle branching occurred as a jump, which we propose as the likely general mechanism. Implications for the Nakata et al. [1998] aim of inferring rupture directivity from branch geometry is that this will be possible only when rather detailed characterization (by surface geology, seismic relocation, trapped waves) of fault connectivity can be carried out in the vicinity of the branching junction, to ascertain whether direct turning of the rupture path through an angle, or jumping and then propagating bilaterally, were involved in prior events. They have opposite implications for how we would associate past directivity with a (nominally) branched fault geometry.

Dmowska, R.; Rice, J. R.; Kame, N.

2002-12-01

168

Selected Hydrologic, Water-Quality, Biological, and Sedimentation Characteristics of Laguna Grande, Fajardo, Puerto Rico, March 2007-February 2009  

USGS Publications Warehouse

Laguna Grande is a 50-hectare lagoon in the municipio of Fajardo, located in the northeasternmost part of Puerto Rico. Hydrologic, water-quality, and biological data were collected in the lagoon between March 2007 and February 2009 to establish baseline conditions and determine the health of Laguna Grande on the basis of preestablished standards. In addition, a core of bottom material was obtained at one site within the lagoon to establish sediment depositional rates. Water-quality properties measured onsite (temperature, pH, dissolved oxygen, specific conductance, and water transparency) varied temporally rather than areally. All physical properties were in compliance with current regulatory standards established for Puerto Rico. Nutrient concentrations were very low and in compliance with current regulatory standards (less than 5.0 and 1.0 milligrams per liter for total nitrogen and total phosphorus, respectively). The average total nitrogen concentration was 0.28 milligram per liter, and the average total phosphorus concentration was 0.02 milligram per liter. Chlorophyll a was the predominant form of photosynthetic pigment in the water. The average chlorophyll-a concentration was 6.2 micrograms per liter. Bottom sediment accumulation rates were determined in sediment cores by modeling the downcore activities of lead-210 and cesium-137. Results indicated a sediment depositional rate of about 0.44 centimeter per year. At this rate of sediment accretion, the lagoon may become a marshland in about 700 to 900 years. About 86 percent of the community primary productivity in Laguna Grande was generated by periphyton, primarily algal mats and seagrasses, and the remaining 14 percent was generated by phytoplankton in the water column. Based on the diel studies the total average net community productivity equaled 5.7 grams of oxygen per cubic meter per day (2.1 grams of carbon per cubic meter per day). Most of this productivity was ascribed to periphyton and macrophytes, which produced 4.9 grams of oxygen per cubic meter per day (1.8 grams of carbon per cubic meter per day). Phytoplankton, the plant and algal component of plankton, produced about 0.8 gram of oxygen per cubic meter per day (0.3 gram of carbon per cubic meter per day). The total diel community respiration rate was 23.4 grams of oxygen per cubic meter per day. The respiration rate ascribed to plankton, which consists of all free floating and swimming organisms in the water column, composed 10 percent of this rate (2.9 grams of oxygen per cubic meter per day); respiration by all other organisms composed the remaining 90 percent (20.5 grams of oxygen per cubic meter per day). Plankton gross productivity was 3.7 grams of oxygen per cubic meter per day, equivalent to about 13 percent of the average gross productivity for the entire community (29.1 grams of oxygen per cubic meter per day). The average phytoplankton biomass values in Laguna Grande ranged from 6.0 to 13.6 milligrams per liter. During the study, Laguna Grande contained a phytoplankton standing crop of approximately 5.8 metric tons. Phytoplankton community had a turnover (renewal) rate of about 153 times per year, or roughly about once every 2.5 days. Fecal indicator bacteria concentrations ranged from 160 to 60,000 colonies per 100 milliliters. Concentrations generally were greatest in areas near residential and commercial establishments, and frequently exceeded current regulatory standards established for Puerto Rico.

Soler-Lopez, Luis R.; Santos, Carlos R.

2010-01-01

169

Central Asia Active Fault Database  

NASA Astrophysics Data System (ADS)

The ongoing collision of the Indian subcontinent with Asia controls active tectonics and seismicity in Central Asia. This motion is accommodated by faults that have historically caused devastating earthquakes and continue to pose serious threats to the population at risk. Despite international and regional efforts to assess seismic hazards in Central Asia, little attention has been given to development of a comprehensive database for active faults in the region. To address this issue and to better understand the distribution and level of seismic hazard in Central Asia, we are developing a publically available database for active faults of Central Asia (including but not limited to Afghanistan, Tajikistan, Kyrgyzstan, northern Pakistan and western China) using ArcGIS. The database is designed to allow users to store, map and query important fault parameters such as fault location, displacement history, rate of movement, and other data relevant to seismic hazard studies including fault trench locations, geochronology constraints, and seismic studies. Data sources integrated into the database include previously published maps and scientific investigations as well as strain rate measurements and historic and recent seismicity. In addition, high resolution Quickbird, Spot, and Aster imagery are used for selected features to locate and measure offset of landforms associated with Quaternary faulting. These features are individually digitized and linked to attribute tables that provide a description for each feature. Preliminary observations include inconsistent and sometimes inaccurate information for faults documented in different studies. For example, the Darvaz-Karakul fault which roughly defines the western margin of the Pamir, has been mapped with differences in location of up to 12 kilometers. The sense of motion for this fault ranges from unknown to thrust and strike-slip in three different studies despite documented left-lateral displacements of Holocene and late Pleistocene landforms observed near the fault trace.

Mohadjer, Solmaz; Ehlers, Todd A.; Kakar, Najibullah

2014-05-01

170

SFT: Scalable Fault Tolerance  

SciTech Connect

In this paper we will present a new technology that we are currently developing within the SFT: Scalable Fault Tolerance FastOS project which seeks to implement fault tolerance at the operating system level. Major design goals include dynamic reallocation of resources to allow continuing execution in the presence of hardware failures, very high scalability, high efficiency (low overhead), and transparency—requiring no changes to user applications. Our technology is based on a global coordination mechanism, that enforces transparent recovery lines in the system, and TICK, a lightweight, incremental checkpointing software architecture implemented as a Linux kernel module. TICK is completely user-transparent and does not require any changes to user code or system libraries; it is highly responsive: an interrupt, such as a timer interrupt, can trigger a checkpoint in as little as 2.5?s; and it supports incremental and full checkpoints with minimal overhead—less than 6% with full checkpointing to disk performed as frequently as once per minute.

Petrini, Fabrizio; Nieplocha, Jarek; Tipparaju, Vinod

2006-04-15

171

Software fault injection for survivability  

Microsoft Academic Search

In this paper, we present an approach and experimental results from using software fault injection to assess information survivability. We define information survivability to mean the ability of an information system to continue to operate in the presence of faults, anomalous system behavior, or malicious attack. In the past, finding and removing software flaws has traditionally been the realm of

J. M. Voas; A. K. Ghosh

2000-01-01

172

Fault Injection for the Masses  

Microsoft Academic Search

The key technology that the author would like to see adopted by the masses is a family of software fault injection algorithms that can predict where to concentrate testing. From a novelty standpoint, these algorithms were (and still are) unique among other methods of performing fault injection. The author concedes that the algorithms are computational, but the results can provide

Jeffrey M. Voas

1997-01-01

173

Fault trees and imperfect coverage  

Microsoft Academic Search

A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault\\/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated

Joanne Bechta Dugan

1989-01-01

174

Surface Creep on California Faults  

NSDL National Science Digital Library

This site provides data from a number of creepmeters in California. A creepmeter is an instrument that monitors the slow surface displacement of an active fault. Its function is not to measure fault slip during earthquakes, but to record the slow aseismic slip between earthquakes.

Bilham, Roger; Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado

175

JPL Fault Protection Software Experiences  

NASA Technical Reports Server (NTRS)

This objectives of this slide presentation are to: (1) Share JPL experiences by describing the evolution of fault protection during its history in deep space exploration, (2) Examine issues of fault protection scope and implementation that affect missions today, and (3) Discuss solutions for the problems of today and tomorrow.

Barltrop, Kevin; Dvorak, Dan

2008-01-01

176

Real-Time Fault Diagnostics  

Microsoft Academic Search

The intelligent process control system (IPCS), an integrated environment for developing complex process control and automation systems is discussed, focusing on its real-time fault diagnostics capability. IPCS has been used to build a supervisory monitoring and diagnostics system for a cogenerator plant. The requirements and problems specific to such systems are examined. The key concepts involved in fault modeling in

Samir Padalkar; Gabor Karsai; Csaba Biegl; Janos Sztipanovits; Koji Okuda; Nobuji Miyasaka

1991-01-01

177

Accelerometer having integral fault null  

NASA Technical Reports Server (NTRS)

An improved accelerometer is introduced. It comprises a transducer responsive to vibration in machinery which produces an electrical signal related to the magnitude and frequency of the vibration; and a decoding circuit responsive to the transducer signal which produces a first fault signal to produce a second fault signal in which ground shift effects are nullified.

Bozeman, Richard J., Jr. (inventor)

1995-01-01

178

Four-dimensional surface deformation analysis, snow volume calculation, and fault mapping with Ground Based Tripod LiDAR  

NASA Astrophysics Data System (ADS)

Ground-based tripod or terrestrial LiDAR (T-LiDAR) has the potential to significantly advance science and hazard assessments in a broad number of research disciplines using remotely collected ultra-high resolution (centimeter to subcentimeter) and accurate (~4 mm) digital imagery of the scanned target. This can be accomplished at distances from 3 to >800 meters, depending on the instrument and target's infrared reflective properties. Scientific analysis of the ultra-high resolution T-LiDAR imagery is through the direct analysis of three-dimensional datasets to calculate target dimensions, volume, and area; alternatively, repeated surveys of the target, differential four-dimensional time-series analysis can be used to evaluate volume change, target stability, surface displacements, or change-detection. Three examples are given that show a range of scientific T-LiDAR application to earth science research: (1) fault mapping at Yucca Flat, Nev.; (2) snow volume calculations in the central Sierra Nevada, Calif.; and (3) hazard mitigation and change-detection and hazard mitigation for the June 1, 2005, Laguna Beach Landslide, southern Calif. The fault-mapping example is a static analysis of many detailed (1- to 5-cm spot spacing) T-LiDAR scans collected on the Nevada Test Site at Yucca Flat at a crater created by an underground nuclear test. The analysis identifies and maps centimeter-level fractures and faults in and near the crater. The level of detail of the T-LiDAR-generated fault and fracture database enhances existing fracture maps. The snow-volume calculation example is a differential analysis of three T-LiDAR surveys at the U.C. Berkeley Central Sierra Snow Lab between March and June 2004. The surveys were aligned and differenced to calculate spatially varying snow volumes. These volumes were combined with water-density measurements to estimate the total water volume. The change detection and hazard-assessment example analyzes repeated T-LiDAR imagery following the June 1, 2005, Laguna Beach Landslide to assess hillslope and structure stability of the slide and the immediate surroundings, and to evaluate T-LiDAR as a hazards response tool. There were no land-surface changes within the landslide after the initial T-LiDAR survey (10 to 21 days after the event) other than minor small-scale readjustments, property recovery efforts, and monitoring within the landslide. T-LiDAR provided direct measurements for the full surrounding region and confirmed that many of the nearby homes were not moving during this time period and could be reinhabited.

Bawden, G. W.; Schmitz, S.; Howle, J. F.; Laczniak, R. J.; Bowers, J.; Osterhuber, R.; Irvine, P.

2005-12-01

179

Availability of ground water in parts of the Acoma and Laguna Indian Reservations, New Mexico  

USGS Publications Warehouse

The need for additional water has increased in recent years on the Acoma and Laguna Indian Reservations in west-central New Mexico because the population and per capita use of water have increased; the tribes also desire water for light industry, for more modern schools, and to increase their irrigation program. Many wells have been drilled in the area, but most have been disappointing because of small yields and poor chemical quality of the water. The topography in the Acoma and Laguna Indian Reservations is controlled primarily by the regional and local dip of alternating beds of sandstone and shale and by the igneous complex of Mount Taylor. The entrenched alluvial valley along the Rio San Jose, which traverses the area, ranges in width from about 0.4 mile to about 2 miles. The climate is characterized by scant rainfall, which occurs mainly in summer, low relative humidity, and large daily fluctuations of temperature. Most of the surface water enters the area through the Rio San Jose. The average annual streamflow past the gaging station Rio San Jose near Grants, N. Mex. is about 4,000 acre-feet. Tributaries to the Rio San Jose within the area probably contribute about 1,000 acre-feet per year. At the present time, most of the surface water is used for irrigation. Ground water is obtained from consolidated sedimentary rocks that range in age from Triassic to Cretaceous, and from unconsolidated alluvium of Quaternary age. The principal aquifers are the Dakota Sandstone, the Tres Hermanos Sandstone Member of the Mancos Shale, and the alluvium. The Dakota Sandstone yields 5 to 50 gpm (gallons per minute) of water to domestic and stock wells. The Tres Hermanos sandstone Member generally yields 5 to 20 gpm of water to domestic and stock wells. Locally, beds of sandstone in the Chinle and Morrison Formations, the Entrada Sandstone, and the Bluff Sandstone also yield small supplies of water to domestic and stock wells. The alluvium yields from 2 gpm to as much as 150 gpm of water to domestic and stock wells. Thirteen test wells were drilled in a search for usable supplies of ground water for pueblo and irrigation supply and to determine the geologic and hydrologic characteristics of the water-bearing material. The performance of six of the test wells suggests that the sites are favorable for pueblo or irrigation supply wells. The yield of the other seven wells was too small or the quality of the water was too poor for development of pueblo or irrigation supply to be feasible. However, the water from one of the seven wells was good in chemical quality, and the yield was large enough to supply a few homes with water. The tests suggest that the water in the alluvium of the Rio San Jose valley is closely related to the streamflow and that it might be possible to withdraw from the alluvium in summer and replenish it in winter. The surface flow in summer might be decreased by extensive pumpage of ground water, but on the other hand, more of the winter flow could be retained in the area by storage in the ground-water reservoir. Wells could be drilled along the axis of the valley, and the water could be pumped into systems for distribution to irrigated farms. The chemical quality of ground water in the area varies widely from one stratigraphic unit to another and laterally within each unit and commonly the water contains undesirably large amounts of sulfate. However, potable water has been obtained locally from all the aquifers. The water of best quality seemingly is in the Tres Hermanos Sandstone Member of the Mancos Shale and in the alluvium north of the Rio San Jose. The largest quantity of water that is suitable for irrigation is in the valley fill along the Rio San Jose. Intensive pumping of ground water from aquifers containing water of good quality may draw water of inferior chemical quality into the wells.

Dinwiddie, George A.; Motts, Ward Sundt.

1964-01-01

180

Arc fault detection system  

DOEpatents

An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard.

Jha, Kamal N. (Bethel Park, PA)

1999-01-01

181

Fault Tolerant Cache Schemes  

NASA Astrophysics Data System (ADS)

Most of modern microprocessors employ on—chip cache memories to meet the memory bandwidth demand. These caches are now occupying a greater real es tate of chip area. Also, continuous down scaling of transistors increases the possi bility of defects in the cache area which already starts to occupies more than 50% of chip area. For this reason, various techniques have been proposed to tolerate defects in cache blocks. These techniques can be classified into three different cat egories, namely, cache line disabling, replacement with spare block, and decoder reconfiguration without spare blocks. This chapter examines each of those fault tol erant techniques with a fixed typical size and organization of L1 cache, through extended simulation using SPEC2000 benchmark on individual techniques. The de sign and characteristics of each technique are summarized with a view to evaluate the scheme. We then present our simulation results and comparative study of the three different methods.

Tu, H.-Yu.; Tasneem, Sarah

182

Improving Multiple Fault Diagnosability using Possible Conflicts  

NASA Technical Reports Server (NTRS)

Multiple fault diagnosis is a difficult problem for dynamic systems. Due to fault masking, compensation, and relative time of fault occurrence, multiple faults can manifest in many different ways as observable fault signature sequences. This decreases diagnosability of multiple faults, and therefore leads to a loss in effectiveness of the fault isolation step. We develop a qualitative, event-based, multiple fault isolation framework, and derive several notions of multiple fault diagnosability. We show that using Possible Conflicts, a model decomposition technique that decouples faults from residuals, we can significantly improve the diagnosability of multiple faults compared to an approach using a single global model. We demonstrate these concepts and provide results using a multi-tank system as a case study.

Daigle, Matthew J.; Bregon, Anibal; Biswas, Gautam; Koutsoukos, Xenofon; Pulido, Belarmino

2012-01-01

183

Populations of faults and fault displacements and their effects on estimates of fault-related regional extension  

NASA Astrophysics Data System (ADS)

Measured populations of fault displacements, derived from regional seismic, oilfield seismic, coalmine plans and outcrop data show a power law distribution with exponents (- S) of -0.45 to -0.95 for singleline samples across an array of faults. The more negative values indicate relatively larger numbers of smaller faults. An expression for a population of active faults, derived from the Gutenberg-Richter magnitude-frequency relation for earthquakes, is log N = a - bD log D, where D = maximum displacement of a fault, N = number of faults of maximum displacement D or greater, and b D ? 1.0 and has the same value as b for the corresponding earthquake population. Populations of 'dead' faults existing at the end of a tectonic episode have been numerically derived, using a fault growth model, and satisfy the relation log N = a - E log D where E has a value between 1.6 and 2.0. Numerically derived populations of fault displacements in a dead fault population have slopes of - S where S = E - 1. The contribution of an individual fault to the regional strain varies with the lifetime seismic moment of the fault and is proportional to D2. Estimation of fault-related extension by summing heaves on faults of a limited size range is valid only if the measured size range of faults accommodates most of the extension. Correction can be made if the S value of the fault displacement population is known.

Walsh, J. J.; Watterson, J.

1992-06-01

184

Relationship between Bouguer anomaly and active fault ( source fault) - For the purpose of estimate of source fault -  

Microsoft Academic Search

Concepts of setting source fault parameters from active faults are discussed for predictions of strong ground motion. Estimation of ground motion plays important rule for the prevention of earthquake hazards. From recent developments in waveform inversion analysis of source fault rupture processes through large earthquakes, it is found that strong ground motion is strongly affected by fault geometry and slip

N. Kitada; N. Inoue; K. Takemura

2008-01-01

185

Fault Injection Campaign for a Fault Tolerant Duplex Framework  

NASA Technical Reports Server (NTRS)

Fault tolerance is an efficient approach adopted to avoid or reduce the damage of a system failure. In this work we present the results of a fault injection campaign we conducted on the Duplex Framework (DF). The DF is a software developed by the UCLA group [1, 2] that uses a fault tolerant approach and allows to run two replicas of the same process on two different nodes of a commercial off-the-shelf (COTS) computer cluster. A third process running on a different node, constantly monitors the results computed by the two replicas, and eventually restarts the two replica processes if an inconsistency in their computation is detected. This approach is very cost efficient and can be adopted to control processes on spacecrafts where the fault rate produced by cosmic rays is not very high.

Sacco, Gian Franco; Ferraro, Robert D.; von llmen, Paul; Rennels, Dave A.

2007-01-01

186

Method of locating ground faults  

NASA Technical Reports Server (NTRS)

The present invention discloses a method of detecting and locating current imbalances such as ground faults in multiwire systems using the Faraday effect. As an example, for 2-wire or 3-wire (1 ground wire) electrical systems, light is transmitted along an optical path which is exposed to magnetic fields produced by currents flowing in the hot and neutral wires. The rotations produced by these two magnetic fields cancel each other, therefore light on the optical path does not read the effect of either. However, when a ground fault occurs, the optical path is exposed to a net Faraday effect rotation due to the current imbalance thereby exposing the ground fault.

Patterson, Richard L. (inventor); Rose, Allen H. (inventor); Cull, Ronald C. (inventor)

1994-01-01

187

Evolution of Rhyolite at Laguna del Maule, a Rapidly Inflating Volcanic Field in the Southern Andes  

NASA Astrophysics Data System (ADS)

The Laguna del Maule Volcanic Field (LdM) is host to both the foremost example of post-glacial rhyolitic volcanism in the southern Andes and rapid, ongoing crustal deformation. The flare-up of high-silica eruptions was coeval with deglaciation at 24 ka. Rhyolite and rhyodacite domes and coulees totaling 6.5 km3 form a 20 km ring around the central lake basin. This spatial and temporal concentration of rhyolite is unprecedented in the history of the volcanic field. Colinear major and trace element variation suggests these lavas share a common evolutionary history (Hildreth et al., 2010). Moreover, geodetic observations (InSAR & GPS) have identified rapid inflation centered in the western side of the rhyolite dome ring at a rate of 17 cm/year for five years, which has accelerated to 30 cm/yr since April 2012. The best fit to the geodetic data is an expanding magma body located at 5 km depth (Fournier et al., 2010; Le Mevel, 2012). The distribution of high-silica volcanism, most notably geochemically similar high-silica rhyolite lavas erupted 12 km apart of opposite sides of the lake within a few kyr of each other, raises the possibility that the shallow magma intrusion represents only a portion of a larger rhyolitic body, potentially of caldera forming dimensions. We aim to combine petrologic models with a precise geochronology to formulate a model of the evolution of the LdM magma system to its current state. New 40Ar/39Ar age determinations show rhyolitic volcanism beginning at 23 ka with the eruption of the Espejos rhyolite, followed by the Cari Launa Rhyolite at 14.5 ka, two flows of the Barrancas complex at 6.4 and 3.9 ka, and the Divisoria rhyolite at 2.2 ka. In contrast, significant andesitic and dacitic volcanism is largely absent from the central basin of LdM since the early post-glacial period suggesting a coincident basin-wide evolution from andesite to dacite to rhyolite and is consistent with a shallow body of low-density rhyolite blocking the eruption of less evolved magma. Temporal trends in the major element compositions of the rhyolite domes show the most evolved was erupted early in the post-glacial period followed by slightly lower-silica rhyolites. Major element fractional crystallization modeling using the rhyolite calibration of the MELTS algorithm (Gualda et al., 2012) largely reproduces the high-silica compositions from a basaltic parental composition. The preferred model predicts 86% crystallization while cooling from 1290° to 800° C at a depth of 5-8 km resulting in a water content of 4-6 wt. % in the residual high-silica magma. Trace element assimilation fractional crystallization modeling predicts only moderate assimilation of anatectic melts and fractionation of zircon and apatite controlling trace element compositions at high silica contents. The suite of recent LdM lavas lies on a single evolutionary pathway supporting a cogenetic source; furthermore, the model parameters are consistent with a shallow magma chamber with the potential to fuel an explosive, caldera-forming eruption.

Andersen, N. L.; Singer, B. S.; Jicha, B. R.; Hildreth, E. W.; Fierstein, J.; Rogers, N. W.

2012-12-01

188

Fault-free performance validation of fault-tolerant multiprocessors  

NASA Technical Reports Server (NTRS)

A validation methodology for testing the performance of fault-tolerant computer systems was developed and applied to the Fault-Tolerant Multiprocessor (FTMP) at NASA-Langley's AIRLAB facility. This methodology was claimed to be general enough to apply to any ultrareliable computer system. The goal of this research was to extend the validation methodology and to demonstrate the robustness of the validation methodology by its more extensive application to NASA's Fault-Tolerant Multiprocessor System (FTMP) and to the Software Implemented Fault-Tolerance (SIFT) Computer System. Furthermore, the performance of these two multiprocessors was compared by conducting similar experiments. An analysis of the results shows high level language instruction execution times for both SIFT and FTMP were consistent and predictable, with SIFT having greater throughput. At the operating system level, FTMP consumes 60% of the throughput for its real-time dispatcher and 5% on fault-handling tasks. In contrast, SIFT consumes 16% of its throughput for the dispatcher, but consumes 66% in fault-handling software overhead.

Czeck, Edward W.; Feather, Frank E.; Grizzaffi, Ann Marie; Segall, Zary Z.; Siewiorek, Daniel P.

1987-01-01

189

Ground-Fault Feeder Detection With Fault-Current and Fault-Resistance Measurement in Mine Power Systems  

Microsoft Academic Search

Many mine power systems operate with a floating neutral or are high-resistance grounded, and earth fault current is no more than a few tens of amperes. Traditional earth-fault-detection methods based on zero-sequence current have poor sensitivity in this case. For improvement, a fault-detection scheme with fault-current and fault-resistance measurement is presented in this paper, which is capable of detecting high-impedance

Xiangjun Zeng; K. K. Li; W. L. Chan; Sheng Su; Yuanyuan Wang

2008-01-01

190

Creating Small Fault Dictionar-ies  

Microsoft Academic Search

Diagnostic fault simulation can generate enormous amounts of data. The techniques used to manage this data can have signi cant e ect on the outcome of the fault diagnosis procedure. We rst demonstrate that if information is removed from a fault dictionary, its ability to diagnose unmodeled faults may be severely curtailed even if dictionary quality metrics remain una ected;

B. Chess; T. Larrabee

1999-01-01

191

Inductive Fault Analysis of MOS Integrated Circuits  

Microsoft Academic Search

Inductive Fault Analysis (IFA) is a systematic Procedure to predict all the faults that are likely to occur in MOS integrated circuit or subcircuit The three major steps of the IFA procedure are: (1) generation of Physical defects using statistical data from the fabrication process; (2) extraction of circuit-level faults caused by these defects; and (3) classification of faults types

John Shen; W. Maly; F. J. Ferguson

1985-01-01

192

Composite fault location for Distribution Management Systems  

Microsoft Academic Search

The problem of fault location is an integral part of Distribution Management System (DMS) solutions. This paper presents a method of locating fault in unsymmetrical networks, including both radial and meshed parts of the network. The real-time information regarding the topological condition of the network and the status updates of the Fault Indicators are used as input to the fault

I. Dzafic; P. Mohapatra; H. T. Neisius

2010-01-01

193

Feedback bridging fault detection using current monitoring  

Microsoft Academic Search

Feedback bridging faults in CMOS circuits are difficult to detect by monitoring logic values. The authors study the possibility of detecting feedback bridging faults by using current monitoring. It is shown that by monitoring current, the feedback bridging faults that cause a metastable state can be detected. Using the same method, the feedback bridging faults can also be detected that

D. Lu; C. Q. Tong

1992-01-01

194

Sensitivity analysis of modular dynamic fault trees  

Microsoft Academic Search

Dynamic fault tree analysis, as currently supported by the Galileo software package, provides an effective means for assessing the reliability of embedded computer-based systems. Dynamic fault trees extend traditional fault trees by defining special gates to capture sequential and functional dependency characteristics. A modular approach to the solution of dynamic fault trees effectively applies Binary Decision Diagram (BOD) and Markov

Yong Ou; Joanne Bechta Dugan

2000-01-01

195

Variance analysis in software fault prediction models  

Microsoft Academic Search

Software fault prediction models play an important role in software quality assurance. They identify software subsystems (modules,components, classes, or files) which are likely to contain faults. These subsystems, in turn, receive additional resources for verification and validation activities. Fault prediction models are binary classifiers typically developed using one of the supervised learning techniques from either a subset of the fault

B Cukic; T Menzies; Y Jiang

2009-01-01

196

Spontaneous Rupture Processes on a Bending Fault  

Microsoft Academic Search

We simulated spontaneous rupture processes on vertical bending faults, using a 3-D finite-difference method. Since shear and normal stresses on the fault depend upon its angle to the principal stresses, rupture velocity and slip ahead of a bending point vary with strike change. Moreover, slip on a bending fault is less than one on a flat fault, since a bending

Y. Kase; S. M. Day

2004-01-01

197

Faults and folds, fact and fiction  

Microsoft Academic Search

After reviewing the microscopic and macroscopic texture of fault zones, the localisation of rupture and creep is described, and the reduced strength of fault zones is investigated. Simple strength and viscosity models for the whole lithosphere play a major role for the geometry of fault zones. Compressional faults (thrusts) show ramp- and flat structures, often soling in a (weak) detachment

R. Meissner

1996-01-01

198

Toward A Quantifiable Definition of Software Faults  

Microsoft Academic Search

An important aspect of developing models relating the number and type of faults in a software system to a set of structural measurement is defining what constitutes a fault. By definition, a fault is a structural imperfection in a software system that may lead to the system's eventually failing. A measurable and precise definition of what faults are makes it

John C. Munson; Allen P. Nikora

2002-01-01

199

Sr Isotopes and Migration of Prairie Mammoths (Mammuthus columbi) from Laguna de las Cruces, San Luis Potosi, Mexico  

NASA Astrophysics Data System (ADS)

Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years, Sr isotopes have been used as a resourceful tracer tool in this context. A comparison of the 87Sr/86Sr ratios found in tooth enamel and in bone is performed to determine if the human skeletal remains belonged to a local or a migrant. Sr in bone approximately reflects the isotopic composition of the geological region where the person lived before death; whereas the Sr isotopic system in tooth enamel is thought to remain as a closed system and thus conserves the isotope ratio acquired during childhood. Sr isotope ratios are obtained through the geologic substrate and its overlying soil, from where an individual got hold of food and water; these ratios are in turn incorporated into the dentition and skeleton during tissue formation. In previous studies from Teotihuacan, Mexico we have shown that a three-step leaching procedure on tooth enamel samples is important to assure that only the biogenic Sr isotope contribution is analyzed. The same Sr isotopic tools can function concerning ancient animal migration patterns. To determine or to discard the mobility of prairie mammoths (Mammuthus columbi) found at Laguna de las Cruces, San Luis Potosi, México the leaching procedure was applied on six molar samples from several fossil remains. The initial hypothesis was to use 87Sr/86Sr values to verify if the mammoth population was a mixture of individuals from various herds and further by comparing their Sr isotopic composition with that of plants and soils, to confirm their geographic origin. The dissimilar Sr results point to two distinct mammoth groups. The mammoth population from Laguna de Cruces was then not a family unit because it was composed by individuals originated from different localities. Only one individual was identified as local. Others could have walked as much as 100 km to find food and water sources.

Solis-Pichardo, G.; Perez-Crespo, V.; Schaaf, P. E.; Arroyo-Cabrales, J.

2011-12-01

200

Recovery of floral and faunal communities after placement of dredged material on seagrasses in Laguna Madre, Texas  

NASA Astrophysics Data System (ADS)

The objectives of this project were to determine how long alterations in habitat characteristics and use by fishery and forage organisms were detectable at dredged material placement sites in Laguna Madre, Texas. Water, sediment, seagrass, benthos, and nekton characteristics were measured and compared among newly deposited sediments and nearby and distant seagrasses each fall and spring over three years. Over this period, 75% of the estimated total surface area of the original deposits was either re-vegetated by seagrass or dispersed by winds and currents. Differences in water and sediment characteristics among habitat types were mostly detected early in the study. There were signs of steady seagrass re-colonization in the latter half of the study period, and mean seagrass coverage of deposits had reached 48% approximately three years after dredging. Clovergrass Halophila engelmannii was the initial colonist, but shoalgrass Halodule wrightii predominated after about one year. Densities of annelids and non-decapod crustaceans were generally significantly greater in close and distant seagrass habitats than in dredged material habitat, whereas densities of molluscs were not significantly related to habitat type. Nekton (fish and decapod) densities were almost always significantly greater in the two seagrass habitats than in dredged material deposits. Benthos and nekton communities in dredged material deposits were distinct from those in seagrass habitats. Recovery from dredged material placement was nearly complete for water column and sediment components after 1.5 to 3 years, but recovery of seagrasses, benthos, and nekton was predicted to take 4 to 8 years. The current 2 to 5 years dredging cycle virtually insures no time for ecosystem recovery before being disturbed again. The only way to ensure permanent protection of the high primary and secondary productivity of seagrass beds in Laguna Madre from acute and chronic effects of maintenance dredging, while ensuring navigation capability, is to remove dredged materials from the shallow waters of the ecosystem.

Sheridan, P.

2004-03-01

201

Implications for mechanical properties of brittle faults from observations of the Punchbowl fault zone, California  

Microsoft Academic Search

Field observations of the Punchbowl fault zone, an inactive trace of the San Andreas, are integrated with results from experimental deformation of naturally deformed Punchbowl fault rocks for a qualitative description of the mechanical properties of the fault and additional information for conceptual models of crustal faulting. The Punchbowl fault zone consists of a single, continuous gouge layer bounded by

F. M. Chester; J. M. Logan

1986-01-01

202

A Fault Prediction Approach for Process Plants using Fault Tree Analysis in Sensor Malfunction  

Microsoft Academic Search

In this paper, a fault prediction approach for process plants using fault tree analysis is presented in the presence of no or false information of certain sensor. The fault propagation model is constructed by causal relationships from fault tree analysis (FTA). Knowledge about system failure, which is obtained from the fault propagation model, is represented as abnormality patterns in process

Zongxiao Yang; Xiaobo Yuan; Zhiqiang Feng; Kazuhiko Suzuki; Akira Inoue

2006-01-01

203

Study on equivalent calculation model of voltage across faulted open port in power system fault analysis  

Microsoft Academic Search

The paper proposes a method to calculate voltage across faulted open port of short circuit fault and open conductor fault in detail. Based on the superposition theory, the formula is deduced to calculate voltage across faulted open port of short circuit fault when the potential values and the phrase angles of generators in power system unequal to each other. On

Li Linlin; Zhao Shiqi; Xing Shuntao; Yuan Wei

2010-01-01

204

Differential Fault Analysis on CLEFIA  

NASA Astrophysics Data System (ADS)

CLEFIA is a new 128-bit block cipher proposed by SONY corporation recently. The fundamental structure of CLEFIA is a generalized Feistel structure consisting of 4 data lines. In this paper, the strength of CLEFIA against the differential fault attack is explored. Our attack adopts the byte-oriented model of random faults. Through inducing randomly one byte fault in one round, four bytes of faults can be simultaneously obtained in the next round, which can efficiently reduce the total induce times in the attack. After attacking the last several rounds' encryptions, the original secret key can be recovered based on some analysis of the key schedule. The data complexity analysis and experiments show that only about 18 faulty ciphertexts are needed to recover the entire 128-bit secret key and about 54 faulty ciphertexts for 192/256-bit keys.

Chen, Hua; Wu, Wenling; Feng, Dengguo

205

Cell boundary fault detection system  

DOEpatents

A method determines a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

Archer, Charles Jens (Rochester, MN) [Rochester, MN; Pinnow, Kurt Walter (Rochester, MN) [Rochester, MN; Ratterman, Joseph D. (Rochester, MN) [Rochester, MN; Smith, Brian Edward (Rochester, MN) [Rochester, MN

2009-05-05

206

Fault Diagnosis in FET Modules.  

National Technical Information Service (NTIS)

The use of Field Effect Transistor (FET) devices in logic design has changed the design emphasis from networks composed of single logic gates to networks composed of complex functional modules. Fault diagnosis techniques which have been discussed in the l...

G. Metze M. Paige

1971-01-01

207

The intermediate principal stress effect on faulting and fault orientation  

NASA Astrophysics Data System (ADS)

We conducted true triaxial compression tests on rectangular prismatic specimens (19×19×38 mm) of siltstone core extracted from a depth of 1252 m, some 140 m below the borehole intersection with the Chelungpu Fault, Taiwan. Experiments consisted of four series of tests in each of which ?3 was kept constant and ?2 was varied from test to test. The major principal stress (?1), aligned with the long vertical side of the specimen, was raised at constant strain rate until a through-going, steeply dipping fault was initiated. As in igneous and metamorphic rocks previously tested, ?1 required to bring about faulting rose as ?2 was set at increasing levels above ?3. This observation reflects the significant contribution of ?2 to the compressive strength, and raises doubt about the suitability of the Mohr-Coulomb criterion. Rather, a strength criterion in terms of the invariants octahedral shear stress (?oct) as a function of mean stress (?oct) provides a good fit to the experimental data. In all tests fault strike was aligned with ?2 direction. The angle (or dip) ? of the fault was also strongly affected by ?2. For constant ?3 the angle rose with ?2, again departing from the Mohr-Coulomb criterion, which predicts a fault angle independent of the intermediate principal stress. The experimental results, revealing the dependence of fault angle ? on ?2, were compared with predictions based on shear localization theory incorporating a yield surface and plastic potential that depend on the following three stress invariants (rather than two, as in Rudnicki and Rice, 1975): ?oct, ?oct, and the Lode angle ?L (=arctan{[2?2 - ?1 - ?3]-[?3 (?1 - ?3)]}). Dependences of the yield surface and plastic potential on mean stress were inferred from the fault angles observed in axisymmetric compression and deviatoric pure shear. Using these relationships to predict fault angle ? for deviatoric stress states other than axisymmetric compression and pure shear, yields good agreement with the experimental observations. The results predict that for constant mean stress, the fault angle ? decreases as the deviatoric stress state varies from axisymmetric extension to axisymmetric compression. For fixed deviatoric stress states, ? decreases monotonically with increasing mean stress.

Haimson, Bezalel; Rudnicki, John

2010-05-01

208

Fault Diagnosis for Timed Automata  

Microsoft Academic Search

In this paper we study the problem of fault diagnosis in the context of dense-time automata. Our work is inspired from (SSL+95, SSL+96), who have studied the problem in the context of discrete event systems (DES) (RW87). We stick to the terminology used in the above papers, although we find the term fault detection, rather than diagnosis, more appropriate. Indeed,

Stavros Tripakis

2002-01-01

209

Types of Faults in California  

NSDL National Science Digital Library

This educational movie made using SCEC-VDO shows the differences between strike-slip faults and thrust faults in southern California.The Southern California Earthquake Center's Virtual Display of Objects SCEC-VDO is 3D visualization software that allows users to display study and make movies of earthquakes as they occur globally. SCEC-VDO was developed by interns of SCEC Undergraduate Studies in Earthquake Information Technology UseIT under the supervision of Sue Perry and Tom Jordan.

Jordan., Interns O.

210

Fault Tree Analysis: A Bibliography  

NASA Technical Reports Server (NTRS)

Fault tree analysis is a top-down approach to the identification of process hazards. It is as one of the best methods for systematically identifying an graphically displaying the many ways some things can go wrong. This bibliography references 266 documents in the NASA STI Database that contain the major concepts. fault tree analysis, risk an probability theory, in the basic index or major subject terms. An abstract is included with most citations, followed by the applicable subject terms.

2000-01-01

211

Software-controlled fault tolerance  

Microsoft Academic Search

adapt to the changing reliability and performance demands of a system. This paper proposes software-controlled fault tolerance, a concept allowing designers and users to tailor their perfor- mance and reliability for each situation. Several software-controllable fault detection techniques are then presented: SWIFT, a software-only technique, and CRAFT, a suite of hybrid hardware\\/ software techniques. Finally, the paper introduces PROFiT, a

George A. Reis; Jonathan Chang; Neil Vachharajani; Ram Rangan; David I. August; Shubhendu S. Mukherjee

2005-01-01

212

Nonlinear Network Dynamics on Earthquake Fault Systems  

SciTech Connect

Earthquake faults occur in interacting networks having emergent space-time modes of behavior not displayed by isolated faults. Using simulations of the major faults in southern California, we find that the physics depends on the elastic interactions among the faults defined by network topology, as well as on the nonlinear physics of stress dissipation arising from friction on the faults. Our results have broad applications to other leaky threshold systems such as integrate-and-fire neural networks.

Rundle, Paul B.; Rundle, John B.; Tiampo, Kristy F.; Sa Martins, Jorge S.; McGinnis, Seth; Klein, W.

2001-10-01

213

Tutorial: Advanced fault tree applications using HARP  

NASA Technical Reports Server (NTRS)

Reliability analysis of fault tolerant computer systems for critical applications is complicated by several factors. These modeling difficulties are discussed and dynamic fault tree modeling techniques for handling them are described and demonstrated. Several advanced fault tolerant computer systems are described, and fault tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that is capable of solving the fault tree models presented.

Dugan, Joanne Bechta; Bavuso, Salvatore J.; Boyd, Mark A.

1993-01-01

214

Earthquake Dynamics at Linked Fault Stepovers  

Microsoft Academic Search

Previous studies of strike-slip fault systems with linking dip-slip faults (Oglesby, 2003) have indicated that with equivalent shear and normal stresses on all segments, extensional stepovers with linking normal faults are more likely to produce multi-segment events that rupture the entire fault system, compared to compressive stepovers with linking thrust faults. This difference is due to the sign of the

D. D. Oglesby

2004-01-01

215

Passive fault current limiting device  

DOEpatents

A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.

Evans, D.J.; Cha, Y.S.

1999-04-06

216

Software Fault Tolerance: A Tutorial  

NASA Technical Reports Server (NTRS)

Because of our present inability to produce error-free software, software fault tolerance is and will continue to be an important consideration in software systems. The root cause of software design errors is the complexity of the systems. Compounding the problems in building correct software is the difficulty in assessing the correctness of software for highly complex systems. After a brief overview of the software development processes, we note how hard-to-detect design faults are likely to be introduced during development and how software faults tend to be state-dependent and activated by particular input sequences. Although component reliability is an important quality measure for system level analysis, software reliability is hard to characterize and the use of post-verification reliability estimates remains a controversial issue. For some applications software safety is more important than reliability, and fault tolerance techniques used in those applications are aimed at preventing catastrophes. Single version software fault tolerance techniques discussed include system structuring and closure, atomic actions, inline fault detection, exception handling, and others. Multiversion techniques are based on the assumption that software built differently should fail differently and thus, if one of the redundant versions fails, it is expected that at least one of the other versions will provide an acceptable output. Recovery blocks, N-version programming, and other multiversion techniques are reviewed.

Torres-Pomales, Wilfredo

2000-01-01

217

Static Rupture Model of the 2010 M7.2 El Mayor-Cucapah Earthquake from ALOS, ENVISAT, SPOT and GPS Data  

NASA Astrophysics Data System (ADS)

The April 4, 2010 "Easter Sunday" earthquake on the US-Mexico border was the largest event to strike Southern California in the last 18 years. The earthquake occurred on a northwest trending fault close to, but not coincident with the identified 1892 Laguna Salada rupture. We investigate coseismic deformation due to the 2010 El Mayor-Cucapah earthquake using Synthetic Aperture Radar (SAR) imagery form ENVISAT and ALOS satellites, optical imagery from SPOT-5 satellite, and continuous and campaign GPS data. The earliest campaign postseismic GPS survey was conducted within days after the earthquake, and provided the near-field cosesmic offsets. Along-track SAR interferograms and amplitude cross-correlation of optical images reveal a relatively simple continuous fault trace with maximum offsets of the order of 3 meters. This is in contrast to the results of geological mapping that portrayed a complex broad zone of distributed faulting. Also, SAR data indicate that the rupture propagated bi-laterally from the epicenter near the town of Durango both to the North-West into the Cucapah mountains and to the South-East into the Mexically valley. The inferred South-East part of the rupture was subsequently field-checked and associated with several fresh scarps, although overall the earthquake fault does not have a conspicuous surface trace South-East of the hypocenter. It is worth noting that the 2010 earthquake propagated into stress shadows of prior events - the Laguna Salada earthquake that ruptured the North-West part of the fault in 1892, and several M6+ earthquakes that ruptured the South-East part of the fault over the last century. Analysis of the coseismic displacement field at the Earth's surface (in particular, the full 3-component displacement field retrieved from SAR and optical imagery) shows a pronounced asymmetry in horizontal displacements across both nodal planes. The maximum displacements are observed in the North-Eastern and South-Western quadrants. This pattern cannot be explained by oblique slip on a quasi-planar fault. Multi-parametric inversions of the space geodetic data suggest that the El Mayor-Cucapah earthquake occurred on a helix-shaped rupture, with Eastward dip in the Northern section and Westward dip in the Southern section. This interpretation is consistent with field observations of the surface rupture and aftershock data, and provides an explanation for a strong non-double-couple component suggested by the seismic moment tensor solution. The total geodetic moment of our best-fitting model is in a good agreement with the seismic moment. We will also discuss effects of the elastic structure on the inferred static rupture model, and observations of early postseismic deformation.

Fialko, Y.; Gonzalez, A.; Gonzalez-Garcia, J. J.; Barbot, S.; Leprince, S.; Sandwell, D. T.; Agnew, D. C.

2010-12-01

218

Aplicacion del paquete de codigos para estimar el termino fuente (STCP) a la Central Nucleoelectrica da Laguna Verde. (Application of the source term code package to obtain a specific source term for the Laguna Verde Nuclear Power Plant. Final report for the period 1 December 1989 - 31 March 1991).  

National Technical Information Service (NTIS)

The main objective of the project was to use the Source Term Code Package (STCP) to obtain a specific source term for those accident sequences deemed dominant as a result of probabilistic safety analyses (PSA) for the Laguna Verde Nuclear Power Plant (CNL...

F. J. Souto

1991-01-01

219

Holocene Amazon rainforest-savanna dynamics and climatic implications: high-resolution pollen record from Laguna Loma Linda in eastern Colombia  

Microsoft Academic Search

We present a high-resolution pollen record of a 695-cm-long sediment core from Laguna Loma Linda, located at an altitude of 310 m in the transitional zone between the savannas of the Llanos Orientales and the Amazonian rainforest, about 100 km from the Eastern Cordillera. Based on eight AMS 14C ages, the record represents the last 8700 14C yr BP. During

Hermann Behling; Henry Hooghiemstra

2000-01-01

220

Incidence of organochlorine pesticides and the health condition of nestling ospreys ( Pandion haliaetus ) at Laguna San Ignacio, a pristine area of Baja California Sur, Mexico  

Microsoft Academic Search

We identified and quantified organochlorine (OC) pesticide residues in the plasma of 28 osprey (Pandion haliaetus) nestlings from a dense population in Laguna San Ignacio, a pristine area of Baja California Sur, Mexico, during the 2001\\u000a breeding season. Sixteen OC pesticides were identified and quantified. ?-, ?-, ?- and ?-hexachlorocyclohexane, heptaclor,\\u000a heptachlor epoxide, endosulfan I and II, endosulfan-sulfate, p,p?-DDE, p,p?-DDD,

Laura B. Rivera-Rodríguez

2011-01-01

221

Anisotropy of permeability in faulted porous sandstones  

NASA Astrophysics Data System (ADS)

Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (?1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

Farrell, N. J. C.; Healy, D.; Taylor, C. W.

2014-06-01

222

Software reliability through fault-avoidance and fault-tolerance  

NASA Technical Reports Server (NTRS)

Twenty independently developed but functionally equivalent software versions were used to investigate and compare empirically some properties of N-version programming, Recovery Block, and Consensus Recovery Block, using the majority and consensus voting algorithms. This was also compared with another hybrid fault-tolerant scheme called Acceptance Voting, using dynamic versions of consensus and majority voting. Consensus voting provides adaptation of the voting strategy to varying component reliability, failure correlation, and output space characteristics. Since failure correlation among versions effectively reduces the cardinality of the space in which the voter make decisions, consensus voting is usually preferable to simple majority voting in any fault-tolerant system. When versions have considerably different reliabilities, the version with the best reliability will perform better than any of the fault-tolerant techniques.

Vouk, Mladen A.; Mcallister, David F.

1991-01-01

223

Identifying wells downstream from Laguna Dam that yield water that will be replaced by water from the Colorado River, Arizona and California  

USGS Publications Warehouse

This report summarizes a comprehensive study and development of the method documented in Owen-Joyce and others (2000). That report and one for the area upstream from Laguna Dam (Wilson and Owen-Joyce, 1994) document the accounting-surface method to identify wells that yield water that will be replaced by water from the Colorado River. Downstream from Laguna Dam, the Colorado River is the source for nearly all recharge to the river aquifer. The complex surface-water and ground-water system that exists in the area is, in part, the result of more than 100 years of water-resources development. Agriculture is the principal economy and is possible only with irrigation. The construction and operation of canals provides the means to divert and distribute Colorado River water to irrigate agricultural lands on the flood plains and mesas along the Colorado and Gila Rivers, in Imperial and Coachella Valleys, and in the area upstream from Dome along the Gila River. Water is withdrawn from wells for irrigation, dewatering, and domestic use. The area downstream from Laguna Dam borders additional areas of agricultural development in Mexico where Colorado River water also is diverted for irrigation.

Owen-Joyce, Sandra J.

2000-01-01

224

Graphite as a fault lubricant  

NASA Astrophysics Data System (ADS)

Graphite is a well-known solid lubricant, and has been found in ~14 vol% of fraction from fault zones in a variety of geological settings (e.g. the Atotsugawa fault system, Japan: Oohashi et al., 2011a, submitted; the KTB borehole, Germany: Zulauf et al., 1990; and the Err nappe detachment fault, Switzerland: Manatschal, 1999). However, it received little attention even though friction of graphite gouge shows strikingly low (steady-state friction coefficient ?0.1) over seven orders of magnitude in slip rate (0.16 ?m/s to 1.3 m/s; Oohashi et al., 2011b). Thus the friction experiments were performed on mixed graphite and quartz gouges with different compositions in order to determine the minimum amount of graphite in reducing the frictional strength of faults dramatically, by using a rotary-shear low to high-velocity friction apparatus. Experimental result clearly indicates that the friction coefficient of the mixture gouge decreases with graphite content following a power-law relation irrespective of slip rate; it starts to reduce at the fraction of 5 vol% and reaches to the almost same level of pure graphite gouge at the fraction of more than 20 vol%. This result implies that the 14 vol% of graphite in natural fault rock is enough amount for reduce the shear strength to half of initial. According to the textural observation, slight weakening of 5-8 vol% of graphite mixture is associated with the development of partial connection of graphite matrix, forming a slip localized surface. On the other hand, the formation of through-going connection of diffused graphite-matrix zones along shear planes is most likely to have caused the dramatic weakening of gouge with graphite of more than 20 vol%. The non-linear power-law dependency of friction on graphite content leads to more efficient reduction of fault strength as compared with the previously reported almost linear dependency on the effects of clay minerals (e.g. Shimamoto & Logan, 1981). Hence the result demonstrates the potential importance of graphite as a weakening agent of mature faults as graphite can reduce friction efficiently as compared with other weak clay minerals. Such mechanical properties of graphite may explain the lack of pronounced heat flow in major crustal faults and the long-term fault weakening.

Oohashi, K.; Hirose, T.; Shimamoto, T.

2011-12-01

225

Transient Faults in Computer Systems  

NASA Technical Reports Server (NTRS)

A powerful technique particularly appropriate for the detection of errors caused by transient faults in computer systems was developed. The technique can be implemented in either software or hardware; the research conducted thus far primarily considered software implementations. The error detection technique developed has the distinct advantage of having provably complete coverage of all errors caused by transient faults that affect the output produced by the execution of a program. In other words, the technique does not have to be tuned to a particular error model to enhance error coverage. Also, the correctness of the technique can be formally verified. The technique uses time and software redundancy. The foundation for an effective, low-overhead, software-based certification trail approach to real-time error detection resulting from transient fault phenomena was developed.

Masson, Gerald M.

1993-01-01

226

Faulting in porous carbonate grainstones  

NASA Astrophysics Data System (ADS)

In the recent past, a new faulting mechanism has been documented within porous carbonate grainstones. This mechanism is due to strain localization into narrow tabular bands characterized by both volumetric and shear strain; for this reason, these features are named compactive shear bands. In the field, compactive shear bands are easily recognizable because they are lightly coloured with respect to the parent rock, and/or show a positive relief because of their increased resistance to weathering. Both characteristics, light colours and positive relief, are a consequence of the compaction processes that characterize these bands, which are the simplest structure element that form within porous carbonate grainstones. With ongoing deformation, the single compactive shear bands, which solve only a few mm of displacement, may evolve into zone of compactive shear bands and, finally, into well-developed faults characterized by slip surfaces and fault rocks. Field analysis conducted in key areas of Italy allow us to documented different modalities of interaction and linkage among the compactive shear bands: (i) a simple divergence of two different compactive shear bands from an original one, (ii) extensional and contractional jogs formed by two continuous, interacting compactive shear bands, and (iii) eye structures formed by collinear interacting compactive shear bands, which have been already described for deformation bands in sandstones. The last two types of interaction may localize the formation of compaction bands, which are characterized by pronounced component of compaction and negligible components of shearing, and/or pressure solution seams. All the aforementioned types of interaction and linkage could happen at any deformation stage, single bands, zone of bands or well developed faults. The transition from one deformation process to another, which is likely to be controlled by the changes in the material properties, is recorded by different ratios and distributions of the fault dimensional attributes. The results of field analysis are consistent with length (L), displacement (D) and thickness (T) of single compactive shear bands clustering around given values, peculiar to the individual lithologies, and does not point out to any scale relationship among these parameters. On the contrary, in zones of shear bands and well-developed faults the D values are maximum in the central portion of individual elements. Differently from what characterize the well-developed faults, in which the slip increments are solved along the main slip surfaces, within zones of compactive shear bands the displacement varies according to the number of individual single bands, so that an increased displacement is related to an higher number of bands. As a consequence, the T-D plot concerning zones of compactive shear bands and well-developed faults show two different populations, which suggest that well-developed faults are much efficient to resolve displacement, with respect the zone of shear bands, because they include sharp slip surfaces. The petrographical and petrophysical properties of the tectonic features described above, which have been assessed by mean of detailed laboratory analyses, are consistent with the single compactive shear bands and zones of shear bands behaving as seals for underground fluid flow with respect to the host rock. These features, strongly present within the fault damage zones of well-developed faults, may compartmentalize the fluid flow in faulted carbonate reservoirs.

Tondi, Emanuele; Agosta, Fabrizio

2010-05-01

227

InSAR measurements around active faults: creeping Philippine Fault and un-creeping Alpine Fault  

NASA Astrophysics Data System (ADS)

Recently, interferometric synthetic aperture radar (InSAR) time-series analyses have been frequently applied to measure the time-series of small and quasi-steady displacements in wide areas. Large efforts in the methodological developments have been made to pursue higher temporal and spatial resolutions by using frequently acquired SAR images and detecting more pixels that exhibit phase stability. While such a high resolution is indispensable for tracking displacements of man-made and other small-scale structures, it is not necessarily needed and can be unnecessarily computer-intensive for measuring the crustal deformation associated with active faults and volcanic activities. I apply a simple and efficient method to measure the deformation around the Alpine Fault in the South Island of New Zealand, and the Philippine Fault in the Leyte Island. I use a small-baseline subset (SBAS) analysis approach (Berardino, et al., 2002). Generally, the more we average the pixel values, the more coherent the signals are. Considering that, for the deformation around active faults, the spatial resolution can be as coarse as a few hundred meters, we can severely 'multi-look' the interferograms. The two applied cases in this study benefited from this approach; I could obtain the mean velocity maps on practically the entire area without discarding decorrelated areas. The signals could have been only partially obtained by standard persistent scatterer or single-look small-baseline approaches that are much more computer-intensive. In order to further increase the signal detection capability, it is sometimes effective to introduce a processing algorithm adapted to the signal of interest. In an InSAR time-series processing, one usually needs to set the reference point because interferograms are all relative measurements. It is difficult, however, to fix the reference point when one aims to measure long-wavelength deformation signals that span the whole analysis area. This problem can be solved by adding the displacement offset in each interferogram as a model parameter and solving the system of equations with the minimum norm condition. This way, the unknown offsets can be automatically determined. By applying this method to the ALOS/PALSAR data acquired over the Alpine Fault, I obtained the mean velocity map showing the right-lateral relative motion of the blocks north and south of the fault and the strain concentration (large velocity gradient) around the fault. The velocity gradient around the fault has along-fault variation, probably reflecting the variation in the fault locking depth. When one aims to detect fault creeps, i.e., displacement discontinuity in space, one can additionally introduce additional parameters to describe the phase ramps in the interferograms and solve the system of equations again with the minimum norm condition. Then, the displacement discontinuity appears more clearly in the result at the cost of suppressing long-wavelength displacements. By applying this method to the ALOS/PALSAR data acquired over the Philippine Fault in Leyte Island, I obtained the mean velocity map showing fault creep at least in the northern and central parts of Leyte at a rate of around 10 mm/year.

Fukushima, Y.

2013-12-01

228

Linking microbial assemblages to paleoenvironmental conditions from the Holocene and Last Glacial Maximum times in Laguna Potrok Aike sediments, Argentina  

NASA Astrophysics Data System (ADS)

Laguna Potrok Aike is a closed basin located in the southern hemisphere's mid-latitudes (52°S) where paleoenvironmental conditions were recorded as temporal sedimentary sequences resulting from variations in the regional hydrological regime and geology of the catchment. The interpretation of the limnogeological multiproxy record developed during the ICDP-PASADO project allowed the identification of contrasting time windows associated with the fluctuations of Southern Westerly Winds. In the framework of this project, a 100-m-long core was also dedicated to a detailed geomicrobiological study which aimed at a thorough investigation of the lacustrine subsurface biosphere. Indeed, aquatic sediments do not only record past climatic conditions, but also provide a wide range of ecological niches for microbes. In this context, the influence of environmental features upon microbial development and survival remained still unexplored for the deep lacustrine realm. Therefore, we investigated living microbes throughout the sedimentary sequence using in situ ATP assays and DAPI cell count. These results, compiled with pore water analysis, SEM microscopy of authigenic concretions and methane and fatty acid biogeochemistry, provided evidence for a sustained microbial activity in deep sediments and pinpointed the substantial role of microbial processes in modifying initial organic and mineral fractions. Finally, because the genetic material associated with microorganisms can be preserved in sediments over millennia, we extracted environmental DNA from Laguna Potrok Aike sediments and established 16S rRNA bacterial and archaeal clone libraries to better define the use of DNA-based techniques in reconstructing past environments. We focused on two sedimentary horizons both displaying in situ microbial activity, respectively corresponding to the Holocene and Last Glacial Maximum periods. Sequences recovered from the productive Holocene record revealed a microbial community adapted to subsaline conditions producing methane with a high potential of organic matter degradation. In contrast, sediments rich in volcanic detritus from the Last Glacial Maximum showed a substantial presence of lithotrophic microorganisms and sulphate-reducing bacteria mediating authigenic minerals. Together, these features suggested that microbial communities developed in response to climatic control of lake and catchment productivity at the time of sediment deposition. Prevailing climatic conditions exerted a hierarchical control on the microbial composition of lake sediments by regulating the influx of organic and inorganic material to the lake basin, which in turn determined water column chemistry, production and sedimentation of particulate material, resulting in the different niches sheltering these microbial assemblages. Moreover, it demonstrated that environmental DNA can constitute sedimentary archives of phylogenetic diversity and diagenetic processes over tens of millennia.

Vuillemin, Aurele; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda

2014-05-01

229

Analysis of the ecosystem structure of Laguna Alvarado, western Gulf of Mexico, by means of a mass balance model  

NASA Astrophysics Data System (ADS)

Alvarado is one of the most productive estuary-lagoon systems in the Mexican Gulf of Mexico. It has great economic and ecological importance due to high fisheries productivity and because it serves as a nursery, feeding, and reproduction area for numerous populations of fishes and crustaceans. Because of this, extensive studies have focused on biology, ecology, fisheries (e.g. shrimp, oysters) and other biological components of the system during the last few decades. This study presents a mass-balanced trophic model for Laguna Alvarado to determine it's structure and functional form, and to compare it with similar coastal systems of the Gulf of Mexico and Mexican Pacific coast. The model, based on the software Ecopath with Ecosim, consists of eighteen fish groups, seven invertebrate groups, and one group each of sharks and rays, marine mammals, phytoplankton, sea grasses and detritus. The acceptability of the model is indicated by the pedigree index (0.5) which range from 0 to 1 based on the quality of input data. The highest trophic level was 3.6 for marine mammals and snappers. Total system throughput reached 2680 t km -2 year -1, of which total consumption made up 47%, respiratory flows made up 37% and flows to detritus made up 16%. The total system production was higher than consumption, and net primary production higher than respiration. The mean transfer efficiency was 13.8%. The mean trophic level of the catch was 2.3 and the primary production required to sustain the catch was estimated in 31 t km -2 yr -1. Ecosystem overhead was 2.4 times the ascendancy. Results suggest a balance between primary production and consumption. In contrast with other Mexican coastal lagoons, Laguna Alvarado differs strongly in relation to the primary source of energy; here the primary producers (seagrasses) are more important than detritus pathways. This fact can be interpreted a response to mangrove deforest, overfishing, etc. Future work might include the compilation of fishing and biomass time trends to develop historical verification and fitting of temporal simulations.

Cruz-Escalona, V. H.; Arreguín-Sánchez, F.; Zetina-Rejón, M.

2007-03-01

230

The Supernova Spectropolarimetry Project: Photometric Followup in the Optical and Near-Infrared by the Mount Laguna Supernova Survey  

NASA Astrophysics Data System (ADS)

The SuperNova SpectroPOLarimetry project (SNSPOL) is a recently formed collaboration between observers and theorists that focuses on decoding the complex, time-dependent spectropolarimetric behavior of supernovae (SNe) of all types. Photometric followup of targeted SNe is provided by the MOunt LAguna SUpernova Survey (MOLASUS), which is carried out using Mount Laguna Observatory's 1-meter telescope. Here we present optical and near-infrared (NIR) photometric observations of three recent SNe that were observed as part of this coordinated effort: SN 2013ej, SN 2013dy, and SN 2014J. We discuss the multi-band light curves of these three SNe, with a particular focus on the use of NIRIM (Meixner et al. 1999), our NIR camera used to obtain the J, H, and K' data. SN 2013ej is a Type II supernova in M74, discovered by the Lick Observatory Supernova Search (LOSS) on 2013 July 25.45 (UT; UT dates are used throughout). Our monitoring of this object began 2013 August 07.88 and continued until 2013 December 13.74. The data provide evidence for aphotospheric phase lasting roughly 70 days from our first observation, with SN 2013ej then declining by about 3 magnitudes in H-band over the following 50 days. SN 2013dy is a Type Ia supernova in NGC 7250 discovered by LOSS on 2013 July 10.45. We monitored SN 2013dy from July 19.89 until 2013 December 13.62. Our observations show a characteristic type Ia light curve that declines in brightness by about 3 magnitudes in H through the course of our monitoring. Lastly, SN 2014J is a Type Ia-HV [High Velocity] (Takaki et. al (2014) - ATEL 5791) in M82, discovered on 2014 January 21.81, and the closest Type Ia supernovae in over three decades. Our monitoring of SN 2014J began on 2014 January 30.67.We acknowledge support from NSF grants AST-1009571 and AST-1210311, under which part of this research was carried out.

Khandrika, Harish G.; Leonard, Douglas C.; Horst, Chuck; Rachubo, Alisa; Duong, Nhieu; Williams, G. Grant; Smith, Paul S.; Smith, Nathan; Milne, Peter; Hoffman, Jennifer L.; Huk, Leah N.; Dessart, Luc

2014-06-01

231

Faulting at Mormon Point, Death Valley, California: A low-angle normal fault cut by high-angle faults  

NASA Astrophysics Data System (ADS)

New geophysical and fault kinematic studies indicate that late Cenozoic basin development in the Mormon Point area of Death Valley, California, was accommodated by fault rotations. Three of six fault segments recognized at Mormon Point are now inactive and have been rotated to low dips during extension. The remaining three segments are now active and moderately to steeply dipping. From the geophysical data, one active segment appears to offset the low-angle faults in the subsurface of Death Valley.

Keener, Charles; Serpa, Laura; Pavlis, Terry L.

1993-04-01

232

Update: San Andreas Fault experiment  

NASA Technical Reports Server (NTRS)

Satellite laser ranging techniques are used to monitor the broad motion of the tectonic plates comprising the San Andreas Fault System. The San Andreas Fault Experiment, (SAFE), has progressed through the upgrades made to laser system hardware and an improvement in the modeling capabilities of the spaceborne laser targets. Of special note is the launch of the Laser Geodynamic Satellite, LAGEOS spacecraft, NASA's only completely dedicated laser satellite in 1976. The results of plate motion projected into this 896 km measured line over the past eleven years are summarized and intercompared.

Christodoulidis, D. C.; Smith, D. E.

1984-01-01

233

Latent Sector Faults and Reliability of Disk Arrays.  

National Technical Information Service (NTIS)

This thesis studies the effects of latent sensor faults on reliability, performance, and combined performability of disk arrays. This is done by developing two novel reliability models that include two fault types: disk unit faults and sector faults. The ...

H. H. Kari

1997-01-01

234

Promises and Fault-Tolerant Database Access.  

National Technical Information Service (NTIS)

This paper studies the power of access, especially fault-tolerant access, to probabilistic databases and to unambiguous databases . We study fault-tolerant access to probabilistic computation, and completely characterize the complexity classes R and ZPP i...

J. Cai L. A. Hemachandra J. Vyskoc

1993-01-01

235

Yield Enhancement by Fault Tolerant Systolic Arrays.  

National Technical Information Service (NTIS)

In this paper interstitial fault tolerance (IFT), a technique for incorporating fault tolerance into systolic arrays in a natural manner, is discussed. IFT can be used for reliable computation or for yield enhancement. Here the author compares IFT used fo...

R. H. Kuhn

1983-01-01

236

Solar Dynamic Power System Fault Diagnosis  

NASA Technical Reports Server (NTRS)

The objective of this research is to conduct various fault simulation studies for diagnosing the type and location of faults in the power distribution system. Different types of faults are simulated at different locations within the distribution system and the faulted waveforms are monitored at measurable nodes such as at the output of the DDCU's. These fault signatures are processed using feature extractors such as FFT and wavelet transforms. The extracted features are fed to a clustering based neural network for training and subsequent testing using previously unseen data. Different load models consisting of constant impedance and constant power are used for the loads. Open circuit faults and short circuit faults are studied. It is concluded from present studies that using features extracted from wavelet transforms give better success rates during ANN testing. The trained ANN's are capable of diagnosing fault types and approximate locations in the solar dynamic power distribution system.

Momoh, James A.; Dias, Lakshman G.

1996-01-01

237

An experimental study of memory fault latency  

NASA Technical Reports Server (NTRS)

The difficulty with the measurement of fault latency is due to the lack of observability of the fault occurrence and error generation instants in a production environment. The authors describe an experiment, using data from a VAX 11/780 under real workload, to study fault latency in the memory subsystem accurately. Fault latency distributions are generated for stuck-at-zero (s-a-0) and stuck-at-one (s-a-1) permanent fault models. The results show that the mean fault latency of an s-a-0 fault is nearly five times that of the s-a-1 fault. An analysis of variance is performed to quantify the relative influence of different workload measures on the evaluated latency.

Chillarege, Ram; Iyer, Ravi K.

1989-01-01

238

Detection of faults and software reliability analysis  

NASA Technical Reports Server (NTRS)

Specific topics briefly addressed include: the consistent comparison problem in N-version system; analytic models of comparison testing; fault tolerance through data diversity; and the relationship between failures caused by automatically seeded faults.

Knight, J. C.

1987-01-01

239

Parametric Modeling and Fault Tolerant Control  

NASA Technical Reports Server (NTRS)

Fault tolerant control is considered for a nonlinear aircraft model expressed as a linear parameter-varying system. By proper parameterization of foreseeable faults, the linear parameter-varying system can include fault effects as additional varying parameters. A recently developed technique in fault effect parameter estimation allows us to assume that estimates of the fault effect parameters are available on-line. Reconfigurability is calculated for this model with respect to the loss of control effectiveness to assess the potentiality of the model to tolerate such losses prior to control design. The control design is carried out by applying a polytopic method to the aircraft model. An error bound on fault effect parameter estimation is provided, within which the Lyapunov stability of the closed-loop system is robust. Our simulation results show that as long as the fault parameter estimates are sufficiently accurate, the polytopic controller can provide satisfactory fault-tolerance.

Wu, N. Eva; Ju, Jianhong

2000-01-01

240

Scaling of fault damage zones with displacement and the implications for fault growth processes  

Microsoft Academic Search

Knowledge of the spatial extent of damage surrounding fault zones is important for understanding crustal fluid flow and also for understanding the physical processes and mechanics by which fault zones develop with slip. There are few data available on the scaling of the fault damage zone with fault displacement, and of those that exist, deriving scaling relationships is hampered by

D. R. Faulkner; T. M. Mitchell; E. Jensen; J. Cembrano

2011-01-01

241

Neural network based fault diagnosis and fault tolerant control for BLDC motor  

Microsoft Academic Search

A fault diagnostics and fault tolerant control system for controller of brushless direct current motor is designed. The neural network state observer is trained by real nonlinear control system. From the residual difference between outputs of actual system and neural network observer, the fault of control system is detected and determined. The simulation results and study on fault diagnostics are

Zheng Li

2009-01-01

242

Fast Protection of Strong Power Systems With Fault Current Limiters and PLL-Aided Fault Detection  

Microsoft Academic Search

In this paper, a new method is proposed that can be used to discriminate faults from switching transients. The method is primarily intended for use in systems where fast fault detection and fast fault clearing before the first peak of the fault current are required. An industrial system, in which high short-circuit power is desired but in which high short-circuit

Magnus Ohrstrom; Lennart Soder

2011-01-01

243

Curved Fault Dynamic Rupture Study: Wasatch Fault Salt Lake City Segment  

NASA Astrophysics Data System (ADS)

Faults are not planar; the curvature of the fault provides us useful information on the earthquake mechanics and faulting (Scholz, 1990). Fault geometry has a profound impact on both static aspect (stress distribution in the fault zone) and dynamic aspect (facilitation and impedance of the fault rupture process) of some fundamental earthquake problems. In most earthquake simulations, planar/piece-wise planar faults are used for numerical simplicity. For real earthquake scenarios, especially ground motion prediction, the eligibility of using simplified planar fault geometry needs to be validated, otherwise the simplification might bias the final conclusion. We analyze the rupture process and ground motion statistics in earthquake simulations for Wasatch Fault -Salt Lake City segment- with different fault configurations. We use a finite element method (Ma & Liu, 2006) to simulate the dynamics of a propagating rupture. We consider various initial stress distribution schemes on the fault (uniform, depth-dependent, random). We want to understand 1) how does the fault geometry itself influence the physical rupture process? and 2) what effect does the curvature have on redistributing the initial stresses on the fault? We will monitor the Coulomb stress change near the fault (Liu et al, 2010). This may provide some indication of the interaction between discontinuous fault segments and dynamic triggering as well as the distribution of aftershocks/foreshocks in relation to the fault geometry.

Liu, Q.; Archuleta, R. J.; Smith, R. B.

2011-12-01

244

Migrating Fault Trees To Decision Trees For Real Time Fault Detection On International Space Station  

Microsoft Academic Search

Fault Tree Analysis shows the possible causes of a system malfunction by enumerating the suspect components and their respective failure modes that may have induced the problem. Complex systems often use fault trees to analyze the faults. Fault diagnosis, when error occurs, is performed by engineers and analysts performing extensive examination of all data gathered during the mission. International Space

Charles Lee; Richard L. Alena; Peter Robinson

2005-01-01

245

Paleomagnetic Data From the Rinconada Fault in Central California: Evidence for Off-fault Deformation  

Microsoft Academic Search

The Rinconada fault is one of three major sub-parallel faults of the San Andreas fault system in central California. The fault has 18 km of dextral displacement since the Pliocene and up to 60 km of total displacement for the Tertiary. A fold and thrust best is well developed in Miocene and younger sedimentary rocks on either side of the

S. Crump; S. Titus; Z. McGuire; B. A. Housen

2009-01-01

246

Fault-tolerant wormhole routing in tori  

Microsoft Academic Search

We present a method to enhance wormhole routing algorithms for deadlock-free fault-tolerant routing in tori. We consider arbitrarily-located faulty blocks and assume only local knowledge of faults. Messages are routed via shortest paths when there are no faults, and this constraint is only slightly relaxed to facilitate routing in the presence of faults. The key concept we use is that,

Suresh Chalasani; Rajendra V. Boppana

1994-01-01

247

Low Angle Normal Fault, Fossil or Active?  

NASA Astrophysics Data System (ADS)

The Panamint Valley - Hunter Mountain - Saline Range (PHS) faults are, together with the Death Valley and Owens Valley faults, one of the three major fault zones within the Eastern California Shear Zone (ECSZ). The ECSZ is the most active fault system bounding the Basin and Range to the southwest with approximately 10 mm/yr of cumulative slip along strike-slip and trans-tensional segments. Previous work has identified the Panamint Valley and Saline Range faults as low angle normal faults and the Hunter Mountain as a transfer fault (Wesnousky and Jones, 1994). A debate exists whether this system is active at present time. Interferometry Synthetic Aperture Radar (InSAR) is a geodetic technique that allows measurement of ground motion at a mm/yr accuracy over large areas with a high measurement sampling. We processed a large number of data to investigate ground motion in the PHS fault system to shed light on the interseismic strain accumulation and its relation to the fault geometry. Preliminary results indicate high strain rate over the Hunter Mountain fault. The locking depth of the fault inferred from elastic modeling of interseismic strain accumulation is on the order of 4km, significantly shallower than for neighboring faults. In contrast, the long wavelength strain field across the Panamint and Saline faults indicates possibly deeper locking depths and/or shallower dip. The shallow locking depth of 4km inferred for the Hunter Mountain fault corresponds with the extension at depth of the two bounding low angle normal faults below Hunter Mountain, suggesting a control by the low angle normal fault system.

Gourmelen, N.; Falk, A.; Manzo, M.; Francesco, C.; Lanari, R.; Johnson, K.

2007-12-01

248

Automatic fault diagnosis of a switching regulator  

NASA Astrophysics Data System (ADS)

This paper describes a microprocessor-based system for the automatic fault diagnosis of a switching regulator. It covers the system from a test philosophy to a working breadboard that correctly identifies single simulated faults in the switching regulator. In addition to open circuit, short circuit, and stuck at faults, the system is capable of diagnosing faults due to excessive leakage, drift in critical components, and system instability.

Nienhaus, H. A.; Palmer, D. E.

249

Application of trishear fault-propagation folding to active reverse faults: examples from the Dalong Fault, Gansu Province, NW China  

NASA Astrophysics Data System (ADS)

Determining accurate fault slip rates at 1 ka to 1 Ma timescales requires well-constrained palinspastic reconstructions of dateable geomorphic and/or geologic markers. Although general kinematic models have been developed to simultaneously reconstruct both bedrock (e.g. bedding and fault attitudes) and neotectonic markers (e.g. strath terraces) along active strike-slip and thrust faults, it is not clear if these models can also account for deformation along steeply dipping (>45°) reverse faults. To address this problem, we have investigated the active, ˜50° dipping, Dalong reverse fault system. This ˜40-km-long fault system forms part of the Aksai restraining stepover along the active, left-slip Altyn Tagh Fault in northwestern China. Our geometric and kinematic analyses show that conventional fault-bend fold models cannot satisfy the steeply-dipping fault geometry we observe in the bedrock record. Likewise, standard fault-propagation fold models fail to match our measurements of a set of fluvial terraces. However, by expanding the trishear model of fault-propagation folding to track both bedrock and neotectonic markers, we are able to match both sets of records. In particular, we have developed trishear kinematic models for two sites (Liuchenzi and Qingyazi) using the numerical modeling program, Fault/Fold v.5.0. This work indicates that an important implication of active trishear fault-propagation folding is that terrace deformation extends for over 1 km on either side of the fault trace. Thus, to accurately measure the total magnitude of vertical separation between matching terraces in the hanging wall and footwall, terrace profiles across active reverse faults must extend 1-2 km on either side of this zone of deformation.

Gold, Ryan D.; Cowgill, Eric; Wang, Xiao-Feng; Chen, Xuan-Hua

2006-02-01

250

Study on fault induced rock bursts  

Microsoft Academic Search

In order to study the rules of rock bursts caused by faults by means of mechanical analysis of a roof rock-mass balanced structure and numerical simulation about fault slip destabilization, the effect of coal mining operation on fault plane stresses and slip displacement were studied. The results indicate that the slip displacement sharply increases due to the decrease of normal

Zhi-hua LI; Lin-ming DOU; Cai-ping LU; Zong-long MU; An-ye CAO

2008-01-01

251

Active faulting and tectonics in China  

Microsoft Academic Search

We present a study of the active tectonics of China based on an interpretation of Landsat (satellite) imagery and supplemented with seismic data. Several important fault systems can be identified, and most are located in regions of high historical seismicity. We deduce the type and sense of faulting from adjacent features seen on these photos, from fault plane solutions of

Paul Tapponnier; Peter Molnar

1977-01-01

252

Short failure analysis under fault isolation  

Microsoft Academic Search

Scanning superconducting quantum interference device (SQUID) microscopy, along with real time X-ray (RTX) microscopy and scanning acoustic microscopy (SAM), was used as a fault isolation tool for IC short circuit failure analysis. Fault isolation was carried out before physical analysis. Experimental procedures and results for both fault isolation and physical analysis are given in detail

Z. H. Mai; M. Palaniappan; J. M. Chin; C. E. Soh; L. A. Knauss; E. F. Fleet

2001-01-01

253

High temperature superconducting fault current limiter  

DOEpatents

A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

Hull, J.R.

1997-02-04

254

High temperature superconducting fault current limiter  

DOEpatents

A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

Hull, John R. (Hinsdale, IL)

1997-01-01

255

Lithospheric elasticity promotes episodic fault activity  

Microsoft Academic Search

Based on the agreement between geodetic and geological plate velocities, interplate fault slip rates are usually considered constant over long periods of time. However, measurements made at different time scales on intracontinental faults suggest that slip rate evolves with time. We examine the slip evolution of a fault embedded in an elastic lithosphere loaded by plate motion. We first assume

Jean Chéry; Philippe Vernant

2006-01-01

256

FAULT & COORDINATION STUDY FOR T PLANT COMPLEX  

SciTech Connect

A short circuit study is performed to determine the maximum fault current that the system protective devices, transformers, and interconnections would he subject to in event of a three phase, phase-to-phase, or phase-to-ground fault. Generally, the short circuit study provides the worst case fault current levels at each bus or connection point of the system.

MCDONALD, G.P.; BOYD-BODIAU, E.A.

2004-09-01

257

Predicting Where Faults Can Hide from Testing  

Microsoft Academic Search

Sensitivity analysis, which estimates the probability that a program location can hide a failure-causing fault, is addressed. The concept of sensitivity is discussed, and a fault\\/failure model that accounts for fault location is presented. Sensitivity analysis requires that every location be analyzed for three properties: the probability of execution occurring, the probability of infection occurring, and the probability of propagation

Jeffrey M. Voas; Larry J. Morell; Keith W. Miller

1991-01-01

258

Recurrent Faults in Objective Test Items.  

ERIC Educational Resources Information Center

A study of recurrent faults in multiple-choice items in Britain's Open University's computer-marked tests has led to a procedure for avoiding these faults. A description of the study covers the incidence and sources of faults (obviousness, memorization, unclear instruction, ambiguity, distractors, inter-item effects, and structure) and…

Stratton, N. J.

1981-01-01

259

Path delay fault simulation of sequential circuits  

Microsoft Academic Search

To analyze path delay faults in synchronous sequential circuits, stimuli are simulated in a dual-vector mode. The signal states represent the logic and transition conditions for two consecutive vectors. After the simulation of each vector, only the activated paths are traced and the corresponding fault effect, if propagated to a flip-flop, is added to its fault list. A path numbering

Soumitra Bose; Prathima Agrawal; Vishwani D. Agrawal

1993-01-01

260

Fault tolerant software modules for SIFT  

NASA Technical Reports Server (NTRS)

The implementation of software fault tolerance is investigated for critical modules of the Software Implemented Fault Tolerance (SIFT) operating system to support the computational and reliability requirements of advanced fly by wire transport aircraft. Fault tolerant designs generated for the error reported and global executive are examined. A description of the alternate routines, implementation requirements, and software validation are included.

Hecht, M.; Hecht, H.

1982-01-01

261

Field Trip to the Hayward Fault Zone  

NSDL National Science Digital Library

This guide provides directions to locations in Hayward, California where visitors can see evidence of creep along the Hayward Fault. There is also information about the earthquake hazards associated with fault zones, earthquake prediction, and landforms associated with offset along a fault. The guide is available in downloadable, printable format (PDF) in two resolutions

262

Fault-Tolerance in Universal Middleware Bridge  

Microsoft Academic Search

Universal middleware bridge (UMB) provides seamless interoperation among heterogeneous home network middleware. There have been high demands for the UMB components (UMB core and adaptors) to have fault- tolerance capabilities. This paper presents a TMO structuring approach together with new implementation techniques for the fault-tolerant TMO-replica structuring scheme called PSTR. PSTR implementations of UMB components provide fault tolerance capabilities essential

Kyung-deok Moon; Jun Hee Park; Liangchen Zheng; Qian Zhou

2008-01-01

263

Information Survivability, Security, and Fault Tolerance  

Microsoft Academic Search

Unlike traditional fault tolerant computing, fault tolerant computing in support of infor- mation survivability must provide access to information in the face of attacks on integrity and availability. One large class of fault tolerant techniques uses a quorum of redundant components to determine what the \\

Matt Bishop

264

Modular approach to fault tree analysis  

Microsoft Academic Search

An analytical method to describe fault tree diagrams in terms of their modular composition is developed. Fault tree structures are characterized by recursively relating the top tree event to all its basic component inputs through a set of equations defining each of the modules for the fault tree. It is shown that such a modular description is an extremely valuable

J. Olmes; L. Wolf

1977-01-01

265

Formal methodology for fault tree construction  

Microsoft Academic Search

A model is presented for formulating the Boolean failure logic, cailed ; the fault tree, for electrical systems from associated schematic diagrams and ; system-independent component information. The model is developed in detail for ; electrical systems, while its implication and terminology extend to all fault ; tree construction. The methodology is verified as formal by fault trees ; constructed

Fussell

1973-01-01

266

Cottage Grove Fault System in Southern Illinois.  

National Technical Information Service (NTIS)

The Cottage Grove Fault System is one of the major tectonic fault systems in southern Illinois. It extends from the Saline-Gallatin County line westward at least as far as Campbell Hill in Jackson County, a distance of about 70 miles. The zone of faulting...

W. J. Nelson H. F. Krausse H. M. Bristol

1981-01-01

267

A fault simulator for MOS LSI circuits  

Microsoft Academic Search

This paper describes a fault simulator for MOS LSI circuits. The basic primitives for this simulator are MOS transistor structures where the transistors are evaluated logically. The simulator provides the capability of modeling and simulating both the classical input\\/output stuck-at faults and the nonclassical transistor stuck-on and stuck-open faults.

A. K. Bose; P. Kozak; C.-Y. Lo; H. N. Nham; E. Pacas-Skewes

1988-01-01

268

A fault simulator for MOS LSI circuits  

Microsoft Academic Search

This paper describes a fault simulator for MOS LSI circuits. The basic primitives for this simulator are MOS transistor structures where the transistors are evaluated logically. The simulator provides the capability of modeling and simulating both the classical input\\/output stuck-at faults and the non-classical transistor stuck-on and stuck-open faults.

A. K. Bose; P. Kozak; C.-Y. Lo; H. N. Nham; E. Pacas-Skewes; K. Wu

1982-01-01

269

On fault detection in CMOS logic networks  

Microsoft Academic Search

This paper considers the problem of detecting faults in CMOS combinational networks. Effects of open and short faults in CMOS networks are analyzed. It is shown that the test sequence must be properly organized if the effects of all open faults are to be observable at the network output terminal. A simple and efficient heuristic method for organizing the test

Kuang-Wei Chiang; Zvonko G. Vranesic

1983-01-01

270

SOFTWARE EVOLUTION AND THE FAULT PROCESS  

Microsoft Academic Search

In developing a software system, we would like to estimate the way in which the fault content changes during its development, as well determine the locations having the highest concentration of faults. In the phases prior to test, however, there may be very little direct in- formation regarding the number and location of faults. This lack of direct information requires

John C. Munson

1998-01-01

271

Estimating Software Fault Content Before Coding  

Microsoft Academic Search

The standard software development process consists of multiple stages: requirements. design, coding, system test, first office. and finally delivery. An objective of this process is to minimize the number of faults in delivered code. Root cause analysis shows that many of the faults can be traced back to requirements or design faults. As part of the software development process, reviews

S. G. Eickt; Clive R. Loader; M. D. Long; Lawrence G. Votta; S. V. Wiel

1992-01-01

272

An empirical investigation of software fault distribution  

Microsoft Academic Search

The paper investigates the distribution of faults within three evolutionary versions or releases of a system software product. A greater concentration of faults was found in certain software program modules as compared to other modules. The fault rates are correlated to the percentage of new and changed lines of code, the module size, and the programming languages used. Additionally, a

Karl-Heinrich Moller; Daniel J. Paulish

1993-01-01

273

Estimating software fault content before coding  

Microsoft Academic Search

The standard software development process consists of multiple stages: requirements, design, coding, system test, first office, and finally delivery. An objective of this process is to minimize the number of faults in delivered code. Root cause analysis shows that many of the faults can be traced back to requirements or design faults. As part of the software development process, reviews

Stephen G. Eick; Clive R. Loader; M. David Long; Lawrence G. Votta; Scott A. Vander Wiel

1992-01-01

274

Measurement and application of fault latency  

NASA Technical Reports Server (NTRS)

The time interval between the occurrence of a fault and the detection of the error caused by the fault is divided by the generation of that error into two parts: fault latency and error latency. Since the moment of error generation is not directly observable, all related works in the literature have dealt with only the sum of fault and error latencies, thereby making the analysis of their separate effects impossible. To remedy this deficiency, (1) a new methodology for indirectly measuring fault latency is presented; the distribution of fault latency is derived from the methodology; and (3) the knowledge of fault latency is applied to the analysis of two important examples. The proposed methodology has been implemented for measuring fault latency in the Fault-Tolerant Multiprocessor (FTMP) at the NASA Airlab. The experimental results show wide variations in the mean fault latencies of different function circuits within FTMP. Also, the measured distributions of fault latency are shown to have monotone hazard rates. Consequently, Gamma and Weibull distributions are selected for the least-squares fit as the distribution of fault latency.

Shin, K. G.; Lee, Y.-H.

1986-01-01

275

COMMENTS ON STACKING FAULT ENERGY OF THORIUM  

Microsoft Academic Search

Transmission electron microscopic studies were made of foils made from ; cold-rolled thorium sheet. Tangled dislocations forming a crude cell structure ; were observed, but no fringes characteristic of stacking faults were visible. No ; example of cross-slip was observed. The results suggest that thorium has an ; intermediate stacking fault energy. The interpretation of stacking fault ; probability as

J. O. Stiegler; C. J. McHargue

1963-01-01

276

Denali Fault: Black Rapids Glacier  

USGS Multimedia Gallery

View eastward along Black Rapids Galcier. The Denali fault follows the trace of the glacier. These very large rockslides went a mile across the glacier on the right side. Investigations of the headwall of the middle landslide indicate a volume at least as large as that which fell, has dropped a mete...

2008-12-15

277

Unified Fault-Tolerance Protocol.  

National Technical Information Service (NTIS)

Davies and Wakerly show that Byzantine fault tolerance can be achieved by a cascade of broadcasts and middle value select functions. We present an extension of the Davies and Wakerly protocol, the unified protocol, and its proof of correctness. We prove t...

P. Miner A. Gedser L. Pike J. Maddalon

2004-01-01

278

Reflection Survey at Barracuda Fault.  

National Technical Information Service (NTIS)

This paper presents the results of a reconnaissance survey conducted by Western Geophysical Company over the Barracuda Fault structure, which is located about 200 miles east of Guadeloupe Island in the West Indies. This was one of the areas selected for e...

L. Paitson C. H. Savit D. M. Blue W. A. Knox

1965-01-01

279

Cell boundary fault detection system  

DOEpatents

An apparatus and program product determine a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

Archer, Charles Jens (Rochester, MN) [Rochester, MN; Pinnow, Kurt Walter (Rochester, MN) [Rochester, MN; Ratterman, Joseph D. (Rochester, MN) [Rochester, MN; Smith, Brian Edward (Rochester, MN) [Rochester, MN

2011-04-19

280

Software Fault Tolerance: A Tutorial  

Microsoft Academic Search

Because of our present inability to produce error-freesoftware, software fault tolerance is and will continue to be animportant consideration in software systems. The root cause ofsoftware design errors is the complexity of the systems.Compounding the problems in building correct software is thedifficulty in assessing the correctness of software for highlycomplex systems. This paper presents a review of software faulttolerance. After

Wilfredo Torres-Pomales

2000-01-01

281

SWIFT: Software Implemented Fault Tolerance  

Microsoft Academic Search

To improve performance and reduce power, processor designers employ advances that shrink feature sizes, lower voltage levels, reduce noise margins, and increase clock rates. However, these advances make processors more susceptible to transient faults that can affect correctness. While reliable systems typically employ hardware techniques to address soft-errors, software techniques can provide a lower-cost and more flexible alternative. This paper

George A. Reis; Jonathan Chang; Neil Vachharajani; Ram Rangan; David I. August

2005-01-01

282

SIFT: software implemented fault tolerance  

Microsoft Academic Search

Many computer applications have stringent requirements for continued correct operation of the computer in the presence of internal faults. The subject of design of such highly reliable computers has been extensively studied, and numerous techniques have been developed to achieve this high reliability. Such computers are termed \\

John H. Wensley

1972-01-01

283

Fault-crossing P delays, epicentral biasing, and fault behavior in Central California  

USGS Publications Warehouse

The P delays across the San Andreas fault zone in central California have been determined from travel-time differences at station pairs spanning the fault, using off-fault local earthquake or quarry blast sources. Systematic delays as large as 0.4 sec have been observed for paths crossing the fault at depths of 5-10 km. These delays can account for the apparent deviation of epicenters from the mapped fault trace. The largest delays occur along the San Andreas fault between San Juan Bautista and Bear Valley and Between Bitterwater Valley and Parkfield. Spatial variations in fault behavior correlate with the magnitude of the fault-crossing P delay. The delay decreases to the northwest of San Juan Bautista across the "locked" section of the San Andreas fault and also decreases to the southeast approaching Parkfield. Where the delay is large, seismicity is relatively high and the fault is creeping. ?? 1979.

Marks, S. M.; Bufe, C. G.

1979-01-01

284

Towards a late Quaternary tephrochronological framework for the southernmost part of South America - the Laguna Potrok Aike tephra record  

NASA Astrophysics Data System (ADS)

A total of 18 tephra samples have been analysed from the composite sediment sequence from Site 2 of the Laguna Potrok Aike ICDP expedition 5022 from southern Patagonia, Argentina, which extends back to ca 51 ka cal BP. Analyses of the volcanic glass show that all layers but one are rhyolitic in composition, with SiO2 contents ranging between ca 74.5 and 78 wt% and suggest an origin in the Austral Andean Volcanic Zone (AVZ; 49-55°S). Nonetheless, two main data clusters occur, one group with K2O contents between ca 1.5 and 2.0 wt%, indicating an origin in the Mt. Burney volcanic area, and one group with K2O contents between ca 2.7 and 3.9 wt%, tentatively correlated with Viedma/Lautaro and the Aguilera volcanoes in the northern part of the AVZ. The early Holocene Tephra, MB1 and the late Pleistocene Reclus R1 tephra occur in the upper part of the sequence. Periods with significant tephra deposition occurred between ca 51-44 ka cal BP, and ca 31-25 ka cal BP, with a decrease in tephra layer frequency between these two periods.

Wastegård, S.; Veres, D.; Kliem, P.; Hahn, A.; Ohlendorf, C.; Zolitschka, B.; Pasado Science Team

285

late Pleistocene and Holocene pollen record from Laguna de las Trancas, northern coastal Santa Cruz County, California  

USGS Publications Warehouse

A 2.1-m core from Laguna de las Trancas, a marsh atop a landslide in northern Santa Cruz County, California, has yielded a pollen record for the period between about 30,000 B. P. and roughly 5000 B. P. Three pollen zones are recognized. The earliest is characterized by high frequencies of pine pollen and is correlated with a mid-Wisconsinan interstade of the mid-continent. The middle zone contains high frequencies of both pine and fir (Abies, probably A. grandis) pollen and is correlated with the last full glacial interval (upper Wisconsinan). The upper zone is dominated by redwood (Sequoia) pollen and represents latest Pleistocene to middle Holocene. The past few thousand years are not represented in the core. The pollen evidence indicates that during the full glacial period the mean annual temperature at the site was about 2°C to 3°C lower than it is today. We attribute this small difference to the stabilizing effect of marine upwelling on the temperature regime in the immediate vicinity of the coast. Precipitation may have been about 20 percent higher as a result of longer winter wet seasons.

Adam, David P.; Byrne, Roger; Luther, Edgar

1981-01-01

286

Luminescence dating of the PASADO core 5022-1D from Laguna Potrok Aike (Argentina) using IRSL signals from feldspar  

NASA Astrophysics Data System (ADS)

We have measured and tested a luminescence chronology for the PASADO core 5022-1D from the maar lake of Laguna Potrok Aike. Because of unsuitable quartz OSL characteristics, sand-sized K-feldspar extracts were chosen as a dosimeter and the dose was measured using a post-IR IRSL (pIRIR290) measurement protocol. Using this approach we were able to access a stable signal and thus avoid the ubiquitous problem of feldspar signal instability. Extensive laboratory tests show that the chosen pIRIR290 protocol is applicable to these samples. We also developed a new criterion based on known relative bleaching rates of the conventional IRSL signal (IR50) and the pIRIR290 signal and the relationship between resulting equivalent doses; this is used to identify and reject poorly bleached samples. Eighteen samples out of 47 were rejected based on this criterion, without reference to absolute doses or stratigraphy; the resulting age-depth profile is self-consistent, increases smoothly with depth and is in agreement with independent age control based on volcanic ash layers (Reclús, Mt Burney and Hudson tephras) at the top and middle of the core. Our new luminescence chronology suggests that the 5022-1D core reaches back to ˜65 ka at ˜96 m below lake floor.

Buylaert, J.-P.; Murray, A. S.; Gebhardt, A. C.; Sohbati, R.; Ohlendorf, C.; Thiel, C.; Wastegård, S.; Zolitschka, B.

2013-07-01

287

A Fault Injection Technique for VHDL Behavioral-Level Models  

Microsoft Academic Search

Fault injection is an important technique for the evaluation of design metrics such as reliability,safety, and fault coverage. Fault injection involves inserting faults into a system and monitoringthe system to determine its behavior in response to the fault. Recently, designers are realizingthe advantages of using simulation to perform fault injection on a model of the design, as opposedto performing the

Todd A. Delong; Barry W. Johnson; Joseph A. Profeta III

1996-01-01

288

Facies composition and scaling relationships of extensional faults in carbonates  

Microsoft Academic Search

Fault seal evaluations in carbonates are challenged by limited input data. Our analysis of 100 extensional faults in shallow-buried layered carbonate rocks aims to improve forecasting of fault core characteristics in these rocks. We have analyzed the spatial distribution of fault core elements described using a Fault Facies classification scheme; a method specifically developed for 3D fault description and quantification,

Eivind Bastesen; Alvar Braathen

2010-01-01

289

Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington  

Microsoft Academic Search

Five trenches across a Holocene fault scarp yield the first radiocarbon-measured earthquake recurrence intervals for a crustal fault in western Washington. The scarp, the first to be revealed by laser im- agery, marks the Toe Jam Hill fault, a north-dipping backthrust to the Seattle fault. Folded and faulted strata, liquefac- tion features, and forest soil A horizons buried by hanging-wall-collapse

Alan R. Nelson; Samuel Y. Johnson; Harvey M. Kelsey; Ray E. Wells; Brian L. Sherrod; Silvio K. Pezzopane; Lee-Ann Bradley; Rich D. Koehler; Robert C. Bucknam

2003-01-01

290

Dynamic fault-tree models for fault-tolerant computer systems  

Microsoft Academic Search

Reliability analysis of fault-tolerant computer systems for critical applications is complicated by several factors. Systems designed to achieve high levels of reliability frequently employ high levels of redundancy, dynamic redundancy management, and complex fault and error recovery techniques. This paper describes dynamic fault-tree modeling techniques for handling these difficulties. Three advanced fault-tolerant computer systems are described: a fault-tolerant parallel processor,

Joanne Bechta Dugan; Salvatore J. Bavuso; Mark A. Boyd

1992-01-01

291

New geomorphic evidence for en échelon fault system in East Karakoram - Jiali Fault zone  

NASA Astrophysics Data System (ADS)

The Karakoram-Jiali Fault zone (KJFZ) is one of the important active fault systems in the Tibetan Plateau. This zone mainly consists of two major faults (i.e., Karakoram fault and Jiali fault) and other minor faults in between. In the middle of KJFZ, there are several en échelon minor faults, such as the faults of Beng Co, Gyaring Co, Lamu Co, and Awong Co. Those faults are all right-lateral strike-slip faults and striking N120°- 130°E. In the east of the Beng Co fault and Jiali Fault, there are still several lineations striking parallel to the Beng Co fault. They are located at 31-32°N, en échelon in configuration, similar in length, and subparallel to each other. In this study they are tentatively regarded as part of the KJFZ. Based on Landsat7 and ASTER satellite imagery, we find a number of geomorphic features to interpret them as active faults. One of above-mentioned minor faults located in the immediate west is identified with the offset of the last glacial moraine, many abandon channels, disrupted stream beds, and shutter ridges, etc. Based on a previously published TL date, the slip rate of this fault is ca. 15 ± 2 mm/yr. According to previous study, the Jiali Fault possesses rapid dextral slip rate (15-20mm/yr) and the maximum observed offset is ca. 1.5km. Both of our imagery analysis and field survey found no evidence to indicate the late Pleistocene activity of the main trace of the Jiali fault. We therefore incline to conclude that instead of the main Jiali Fault those en échelon faults in its west are relatively more active at least since late Pleistocene.

Chung, L.; Chen, Y.; Yu, T.; Cao, Z.; Yin, G.

2008-12-01

292

Architecture of small-scale fault zones in the context of the Leinetalgraben Fault System  

Microsoft Academic Search

Understanding fault zone properties in different geological settings is important to better assess the development and propagation of faults. In addition this allows better evaluation and permeability estimates of potential fault-related geothermal reservoirs. The Leinetalgraben fault system provides an outcrop analogue for many fault zones in the subsurface of the North German Basin. The Leinetalgraben is a N-S-trending graben structure,

Dorothea Reyer; Sonja L. Philipp

2010-01-01

293

Dealing with dormant faults in an embedded fault-tolerant computer system  

Microsoft Academic Search

Accumulation of dormant faults is a potential threat in a fault tolerant system, especially because most often fault tolerance is based on the single-fault assumption. We investigate this threat by the example of an automotive steer-by-wire application based on the Time-Triggered Architecture (TTA). By means of a Markov model we illustrate that the effect of fault dormancy can degrade the

C. Scherrer; A. Steininger

2003-01-01

294

Fault Diagnosis in HVAC Chillers  

NASA Technical Reports Server (NTRS)

Modern buildings are being equipped with increasingly sophisticated power and control systems with substantial capabilities for monitoring and controlling the amenities. Operational problems associated with heating, ventilation, and air-conditioning (HVAC) systems plague many commercial buildings, often the result of degraded equipment, failed sensors, improper installation, poor maintenance, and improperly implemented controls. Most existing HVAC fault-diagnostic schemes are based on analytical models and knowledge bases. These schemes are adequate for generic systems. However, real-world systems significantly differ from the generic ones and necessitate modifications of the models and/or customization of the standard knowledge bases, which can be labor intensive. Data-driven techniques for fault detection and isolation (FDI) have a close relationship with pattern recognition, wherein one seeks to categorize the input-output data into normal or faulty classes. Owing to the simplicity and adaptability, customization of a data-driven FDI approach does not require in-depth knowledge of the HVAC system. It enables the building system operators to improve energy efficiency and maintain the desired comfort level at a reduced cost. In this article, we consider a data-driven approach for FDI of chillers in HVAC systems. To diagnose the faults of interest in the chiller, we employ multiway dynamic principal component analysis (MPCA), multiway partial least squares (MPLS), and support vector machines (SVMs). The simulation of a chiller under various fault conditions is conducted using a standard chiller simulator from the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). We validated our FDI scheme using experimental data obtained from different types of chiller faults.

Choi, Kihoon; Namuru, Setu M.; Azam, Mohammad S.; Luo, Jianhui; Pattipati, Krishna R.; Patterson-Hine, Ann

2005-01-01

295

Fault-Tolerant Heat Exchanger  

NASA Technical Reports Server (NTRS)

A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

Izenson, Michael G.; Crowley, Christopher J.

2005-01-01

296

Fault tolerant control of spacecraft  

NASA Astrophysics Data System (ADS)

Autonomous multiple spacecraft formation flying space missions demand the development of reliable control systems to ensure rapid, accurate, and effective response to various attitude and formation reconfiguration commands. Keeping in mind the complexities involved in the technology development to enable spacecraft formation flying, this thesis presents the development and validation of a fault tolerant control algorithm that augments the AOCS on-board a spacecraft to ensure that these challenging formation flying missions will fly successfully. Taking inspiration from the existing theory of nonlinear control, a fault-tolerant control system for the RyePicoSat missions is designed to cope with actuator faults whilst maintaining the desirable degree of overall stability and performance. Autonomous fault tolerant adaptive control scheme for spacecraft equipped with redundant actuators and robust control of spacecraft in underactuated configuration, represent the two central themes of this thesis. The developed algorithms are validated using a hardware-in-the-loop simulation. A reaction wheel testbed is used to validate the proposed fault tolerant attitude control scheme. A spacecraft formation flying experimental testbed is used to verify the performance of the proposed robust control scheme for underactuated spacecraft configurations. The proposed underactuated formation flying concept leads to more than 60% savings in fuel consumption when compared to a fully actuated spacecraft formation configuration. We also developed a novel attitude control methodology that requires only a single thruster to stabilize three axis attitude and angular velocity components of a spacecraft. Numerical simulations and hardware-in-the-loop experimental results along with rigorous analytical stability analysis shows that the proposed methodology will greatly enhance the reliability of the spacecraft, while allowing for potentially significant overall mission cost reduction.

Godard

297

The occurrence of graphite-bearing fault rocks in the Atotsugawa fault system, Japan: Origins and implications for fault creep  

NASA Astrophysics Data System (ADS)

Graphite in fault zones has received little attention even though it is a well-known solid lubricant that could affect frictional properties of faults dramatically. This paper reports the presence of abundant graphite in fault zones of the Atotsugawa fault system, central Japan. Mesoscopic and microscopic observations of fault rocks revealed two processes of carbon enrichment in fault zones. One is a pressure solution process or diffusive mass transfer in general which removes water-soluble minerals such as quartz and carbonates from rocks, resulting in the enrichment of insoluble minerals including carbon. The other process is precipitation of graphite from a high-temperature carbon-rich fluid, forming graphite filling fractures within cataclasitic fault zones. The two processes have led to the concentration, up to 12 wt% of graphite, in the Atotsugawa fault zones, compared to 0 to 3 wt% of carbonaceous materials in the host rocks. This concentration is high enough for graphite to affect frictional properties at wide range of slip rates. The presence of graphite may provide an explanation for the low resistivity, the patterns of microearthquakes and fault creep along the western part of the Atotsugawa fault system. Graphite should receive more attention as a weakening and stabilizing agent of faults.

Oohashi, Kiyokazu; Hirose, Takehiro; Kobayashi, Kenta; Shimamoto, Toshihiko

2012-05-01

298

Predeployment validation of fault-tolerant systems through software-implemented fault insertion  

NASA Technical Reports Server (NTRS)

Fault injection-based automated testing (FIAT) environment, which can be used to experimentally characterize and evaluate distributed realtime systems under fault-free and faulted conditions is described. A survey is presented of validation methodologies. The need for fault insertion based on validation methodologies is demonstrated. The origins and models of faults, and motivation for the FIAT concept are reviewed. FIAT employs a validation methodology which builds confidence in the system through first providing a baseline of fault-free performance data and then characterizing the behavior of the system with faults present. Fault insertion is accomplished through software and allows faults or the manifestation of faults to be inserted by either seeding faults into memory or triggering error detection mechanisms. FIAT is capable of emulating a variety of fault-tolerant strategies and architectures, can monitor system activity, and can automatically orchestrate experiments involving insertion of faults. There is a common system interface which allows ease of use to decrease experiment development and run time. Fault models chosen for experiments on FIAT have generated system responses which parallel those observed in real systems under faulty conditions. These capabilities are shown by two example experiments each using a different fault-tolerance strategy.

Czeck, Edward W.; Siewiorek, Daniel P.; Segall, Zary Z.

1989-01-01

299

Deformation associated with continental normal faults  

NASA Astrophysics Data System (ADS)

Deformation associated with normal fault earthquakes and geologic structures provide insights into the seismic cycle as it unfolds over time scales from seconds to millions of years. Improved understanding of normal faulting will lead to more accurate seismic hazard assessments and prediction of associated structures. High-precision aftershock locations for the 1995 Kozani-Grevena earthquake (Mw 6.5), Greece image a segmented master fault and antithetic faults. This three-dimensional fault geometry is typical of normal fault systems mapped from outcrop or interpreted from reflection seismic data and illustrates the importance of incorporating three-dimensional fault geometry in mechanical models. Subsurface fault slip associated with the Kozani-Grevena and 1999 Hector Mine (Mw 7.1) earthquakes is modeled using a new method for slip inversion on three-dimensional fault surfaces. Incorporation of three-dimensional fault geometry improves the fit to the geodetic data while honoring aftershock distributions and surface ruptures. GPS Surveying of deformed bedding surfaces associated with normal faulting in the western Grand Canyon reveals patterns of deformation that are similar to those observed by interferometric satellite radar interferometry (InSAR) for the Kozani Grevena earthquake with a prominent down-warp in the hanging wall and a lesser up-warp in the footwall. However, deformation associated with the Kozani-Grevena earthquake extends ˜20 km from the fault surface trace, while the folds in the western Grand Canyon only extend 500 m into the footwall and 1500 m into the hanging wall. A comparison of mechanical and kinematic models illustrates advantages of mechanical models in exploring normal faulting processes including incorporation of both deformation and causative forces, and the opportunity to incorporate more complex fault geometry and constitutive properties. Elastic models with antithetic or synthetic faults or joints in association with a master normal fault illustrate how these secondary structures influence the deformation in ways that are similar to fault/fold geometry mapped in the western Grand Canyon. Specifically, synthetic faults amplify hanging wall bedding dips, antithetic faults reduce dips, and joints act to localize deformation. The distribution of aftershocks in the hanging wall of the Kozani-Grevena earthquake suggests that secondary structures may accommodate strains associated with slip on a master fault during postseismic deformation.

Resor, Phillip G.

300

Detection of faults and software reliability analysis  

NASA Technical Reports Server (NTRS)

Multiversion or N-version programming was proposed as a method of providing fault tolerance in software. The approach requires the separate, independent preparation of multiple versions of a piece of software for some application. Specific topics addressed are: failure probabilities in N-version systems, consistent comparison in N-version systems, descriptions of the faults found in the Knight and Leveson experiment, analytic models of comparison testing, characteristics of the input regions that trigger faults, fault tolerance through data diversity, and the relationship between failures caused by automatically seeded faults.

Knight, J. C.

1986-01-01

301

Expulsion of abnormally pressured fluids along faults  

NASA Astrophysics Data System (ADS)

Numerical simulations of fluid flow and heat transport in the South Eugene Island minibasin, offshore Louisiana, show that expulsion of geopressured fluids along faults can produce temperature and pressure anomalies similar to those observed in the area. In the simulations, abnormally pressured fluid moves along the fault through a fracture network. A thermal anomaly forms adjacent to the fault, while a larger fluid pressure anomaly extends into sediments on either side. Results from constant fault permeability simulations indicate that (1) geopressured sediments must be relatively permeable (5 × 10-17 m2) for expulsion to occur, (2) the size of thermal anomalies depend on the depth to which the fault is hydraulically open, and (3) fluid is vertically transported into shallow sediments when fault permeability is high, while lateral transport along deeper sands dominates when fault permeability is low. Excess fluid pressure in abnormally pressured sediments drops to half its original value throughout much of the minibasin after 10,000 years of expulsion; the associated thermal anomaly is also larger than observations, suggesting expulsion is not continuous. Variable fault permeability simulations, in which compaction of fault zone sediments closes the fracture network, indicate that fault permeability decreases by 1-2 orders of magnitude 1-200 years after expulsion begins. Thermal and baric anomalies from variable permeability simulations are smaller than from constant permeability simulations and are more consistent with available data. Faults must remain permeable for 20-30 years to produce thermal and baric anomalies similar to those observed in the area.

Roberts, Sheila J.; Nunn, Jeffrey A.; Cathles, Larry; Cipriani, Francois-Dominique

1996-12-01

302

Rupture dynamics of a geometrically complex fault  

NASA Astrophysics Data System (ADS)

We study the propagation of a two dimensional antiplane rupture along a complex geometrical fault containing a series of kinks of different angles and intervals between the kinks. Numerical solutions are obtained using the spectral element methods developed by Vilotte, Ampuero and Komatisch. We model both periodically kinked and simple versions of randomly kinked faults. We compare our simulations with the results obtained for rupture propagation along flat faults. We find that geometrically complex differ substantially from flat faults. First, complex faults emit high frequency radiation of ?-2 type every time they encounter geometrical discontinuities, this produces a strong damping of rupture propagation. Second, the average rupture speed along the overall direction of the fault is substantially reduced and, depending on the nature of the geometrical discontinuities, ruptures may be easily stopped. Energy release rates computed assuming that the fault is flat increase as the fault becomes increasingly complex. The stress field around the fault may be described as a corridor of strongly variable stress with patches of stress increase and decrease even if the slip on the fault is continuous. Contrary to flat faults, earthquake propagation leaves behind a complex final state of stress. Our model confirms the experimental findings of many authors who worked on high speed mode I fracture.

Madariaga, R. I.; Ampuero, J.

2005-12-01

303

Model-Based Fault Tolerant Control  

NASA Technical Reports Server (NTRS)

The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

Kumar, Aditya; Viassolo, Daniel

2008-01-01

304

Wrench faulting using seismic and Landsat  

SciTech Connect

Two high-multiplicity seismic profiles demonstrate the compressional nature of the faulting along the Double Mountain Lineament in northeast Garza County in the Permian basin. NASA high-altitude aircraft imagery using Landsat parameters delineate the traces of these faults on the surface. The drainage system also defines the fault traces by following the zones of fracture and weakness in the Permian and Triassic outcrops. A north-south seismic profile crosses the Double Mountain lineament (P Shear), defining two thrust faults, two high-angle reverse faults and a pop-up block (flow structure). NASA high-altitude imagery and stream drainage indicate the traces of these faults. The pattern developed fits the definition of left lateral wrench faulting. Overlying carbonate shelf margins are developed above the underlying structure, which further enhances the structural interpretation. An east-west seismic profile 3 mi southeast of the north-south profile again defines the Double Mountain Lineament or P Shear and the associated faulting. A 1-mi wide pop-up block with a high angle reverse fault on both sides demonstrates the compressional nature of the faulting, and the high-altitude imagery delineates the surface traces of the faults. This structure has been drilled with several Stawn and Ellenburger producers, confirming the seismic and surface interpretations in the subsurface.

Bolden, G.P.

1987-05-01

305

Experiments in fault tolerant software reliability  

NASA Technical Reports Server (NTRS)

Twenty functionally equivalent programs were built and tested in a multiversion software experiment. Following unit testing, all programs were subjected to an extensive system test. In the process sixty-one distinct faults were identified among the versions. Less than 12 percent of the faults exhibited varying degrees of positive correlation. The common-cause (or similar) faults spanned as many as 14 components. However, a majority of these faults were trivial, and easily detected by proper unit and/or system testing. Only two of the seven similar faults were difficult faults, and both were caused by specification ambiguities. One of these faults exhibited variable identical-and-wrong response span, i.e. response span which varied with the testing conditions and input data. Techniques that could have been used to avoid the faults are discussed. For example, it was determined that back-to-back testing of 2-tuples could have been used to eliminate about 90 percent of the faults. In addition, four of the seven similar faults could have been detected by using back-to-back testing of 5-tuples. It is believed that most, if not all, similar faults could have been avoided had the specifications been written using more formal notation, the unit testing phase was subject to more stringent standards and controls, and better tools for measuring the quality and adequacy of the test data (e.g. coverage) were used.

Mcallister, David F.; Vouk, Mladen A.

1989-01-01

306

Tool for Viewing Faults Under Terrain  

NASA Technical Reports Server (NTRS)

Multi Surface Light Table (MSLT) is an interactive software tool that was developed in support of the QuakeSim project, which has created an earthquake- fault database and a set of earthquake- simulation software tools. MSLT visualizes the three-dimensional geometries of faults embedded below the terrain and animates time-varying simulations of stress and slip. The fault segments, represented as rectangular surfaces at dip angles, are organized into collections, that is, faults. An interface built into MSLT queries and retrieves fault definitions from the QuakeSim fault database. MSLT also reads time-varying output from one of the QuakeSim simulation tools, called "Virtual California." Stress intensity is represented by variations in color. Slips are represented by directional indicators on the fault segments. The magnitudes of the slips are represented by the duration of the directional indicators in time. The interactive controls in MSLT provide a virtual track-ball, pan and zoom, translucency adjustment, simulation playback, and simulation movie capture. In addition, geographical information on the fault segments and faults is displayed on text windows. Because of the extensive viewing controls, faults can be seen in relation to one another, and to the terrain. These relations can be realized in simulations. Correlated slips in parallel faults are visible in the playback of Virtual California simulations.

Siegel, Herbert, L.; Li, P. Peggy

2005-01-01

307

Rule-based fault diagnosis of hall sensors and fault-tolerant control of PMSM  

NASA Astrophysics Data System (ADS)

Hall sensor is widely used for estimating rotor phase of permanent magnet synchronous motor(PMSM). And rotor position is an essential parameter of PMSM control algorithm, hence it is very dangerous if Hall senor faults occur. But there is scarcely any research focusing on fault diagnosis and fault-tolerant control of Hall sensor used in PMSM. From this standpoint, the Hall sensor faults which may occur during the PMSM operating are theoretically analyzed. According to the analysis results, the fault diagnosis algorithm of Hall sensor, which is based on three rules, is proposed to classify the fault phenomena accurately. The rotor phase estimation algorithms, based on one or two Hall sensor(s), are initialized to engender the fault-tolerant control algorithm. The fault diagnosis algorithm can detect 60 Hall fault phenomena in total as well as all detections can be fulfilled in 1/138 rotor rotation period. The fault-tolerant control algorithm can achieve a smooth torque production which means the same control effect as normal control mode (with three Hall sensors). Finally, the PMSM bench test verifies the accuracy and rapidity of fault diagnosis and fault-tolerant control strategies. The fault diagnosis algorithm can detect all Hall sensor faults promptly and fault-tolerant control algorithm allows the PMSM to face failure conditions of one or two Hall sensor(s). In addition, the transitions between health-control and fault-tolerant control conditions are smooth without any additional noise and harshness. Proposed algorithms can deal with the Hall sensor faults of PMSM in real applications, and can be provided to realize the fault diagnosis and fault-tolerant control of PMSM.

Song, Ziyou; Li, Jianqiu; Ouyang, Minggao; Gu, Jing; Feng, Xuning; Lu, Dongbin

2013-07-01

308

Multiple Fault Isolation in Redundant Systems  

NASA Technical Reports Server (NTRS)

We consider the problem of sequencing tests to isolate multiple faults in redundant (fault-tolerant) systems with minimum expected testing cost (time). It can be shown that single faults and minimal faults, i.e., minimum number of failures with a failure signature different from the union of failure signatures of individual failures, together with their failure signatures, constitute the necessary information for fault diagnosis in redundant systems. In this paper, we develop an algorithm to find all the minimal faults and their failure signatures. Then, we extend the Sure diagnostic strategies [1] of our previous work to diagnose multiple faults in redundant systems. The proposed algorithms and strategies are illustrated using several examples.

Shakeri, M.; Pattipati, Krishna R.; Raghavan, V.; Patterson-Hine, Ann; Iverson, David L.

1997-01-01

309

Naval weapons center active fault map series  

NASA Astrophysics Data System (ADS)

The NWC Active Fault Map Series shows the locations of active faults and features indicative of active faulting within much of Indian Wells Valley and portions of the Randsburg Wash/Mojave B test range areas of the Naval Weapons Center. Map annotations are used extensively to identify criteria employed in identifying the fault offsets, and to present other valuable data. All of the mapped faults show evidence of having moved during about the last 12,500 years or represent geologically young faults that occur within seismic gaps. Only faults that offset the surface or show other evidence of surface deformation were mapped. A portion of the City of Ridgecrest is recommended as being a Seismic Hazard Special Studies Zone in which detailed earthquake hazard studies should be required.

Roquemore, G. R.; Zellmer, J. T.

1987-08-01

310

Arc burst pattern analysis fault detection system  

NASA Technical Reports Server (NTRS)

A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

1997-01-01

311

Alp Transit: Crossing Faults 44 and 49  

NASA Astrophysics Data System (ADS)

This paper describes the crossing of faults 44 and 49 when constructing the 57 km Gotthard base tunnel of the Alp Transit project. Fault 44 is a permeable fault that triggered significant surface deformations 1,400 m above the tunnel when it was reached by the advancing excavation. The fault runs parallel to the downstream face of the Nalps arch dam. Significant deformations were measured at the dam crown. Fault 49 is sub-vertical and permeable, and runs parallel at the upstream face of the dam. It was necessary to assess the risk when crossing fault 49, as a limit was put on the acceptable dam deformation for structural safety. The simulation model, forecasts and action decided when crossing over the faults are presented, with a brief description of the tunnel, the dam, and the monitoring system.

El Tani, M.; Bremen, R.

2014-05-01

312

Silica Lubrication in Faults (Invited)  

NASA Astrophysics Data System (ADS)

Silica-rich rocks are common in the crust, so silica lubrication may be important for causing fault weakening during earthquakes if the phenomenon occurs in nature. In laboratory friction experiments on chert, dramatic shear weakening has been attributed to amorphization and attraction of water from atmospheric humidity to form a 'silica gel'. Few observations of the slip surfaces have been reported, and the details of weakening mechanism(s) remain enigmatic. Therefore, no criteria exist on which to make comparisons of experimental materials to natural faults. We performed a series of friction experiments, characterized the materials formed on the sliding surface, and compared these to a geological fault in the same rock type. Experiments were performed in the presence of room humidity at 2.5 MPa normal stress with 3 and 30 m total displacement for a variety of slip rates (10-4 - 10-1 m/s). The friction coefficient (?) reduced from >0.6 to ~0.2 at 10-1 m/s, but only fell to ~0.4 at 10-2 - 10-4 m/s. The slip surfaces and wear material were observed using laser confocal Raman microscopy, electron microprobe, X-ray diffraction, and transmission electron microscopy. Experiments at 10-1 m/s formed wear material consisting of ?1 ?m powder that is aggregated into irregular 5-20 ?m clumps. Some material disaggregated during analysis with electron beams and lasers, suggesting hydrous and unstable components. Compressed powder forms smooth pavements on the surface in which grains are not visible (if present, they are <100 nm). Powder contains amorphous material and as yet unidentified crystalline and non-crystalline forms of silica (not quartz), while the worn chert surface underneath shows Raman spectra consistent with a mixture of quartz and amorphous material. If silica amorphization facilitates shear weakening in natural faults, similar wear materials should be formed, and we may be able to identify them through microstructural studies. However, the sub-micron particles of unstable materials are unlikely to survive in the crust over geologic time, so a direct comparison of fresh experimental wear material and ancient fault rock needs to account for the alteration and crystallization of primary materials. The surface of the Corona fault is coated by a translucent shiny layer consisting of ~100 nm interlocking groundmass of dislocation-free quartz, 10 nm ellipsoidal particles, and interstitial patches of amorphous silica. We interpret this layer as the equivalent of the experimentally produced amorphous material after crystallizing to more stable forms over geological time.

Rowe, C. D.; Rempe, M.; Lamothe, K.; Kirkpatrick, J. D.; White, J. C.; Mitchell, T. M.; Andrews, M.; Di Toro, G.

2013-12-01

313

Frictional constraints on crustal faulting  

USGS Publications Warehouse

We consider how variations in fault frictional properties affect the phenomenology of earthquake faulting. In particular, we propose that lateral variations in fault friction produce the marked heterogeneity of slip observed in large earthquakes. We model these variations using a rate- and state-dependent friction law, where we differentiate velocity-weakening behavior into two fields: the strong seismic field is very velocity weakening and the weak seismic field is slightly velocity weakening. Similarly, we differentiate velocity-strengthening behavior into two fields: the compliant field is slightly velocity strengthening and the viscous field is very velocity strengthening. The strong seismic field comprises the seismic slip concentrations, or asperities. The two "intermediate" fields, weak seismic and compliant, have frictional velocity dependences that are close to velocity neutral: these fields modulate both the tectonic loading and the dynamic rupture process. During the interseismic period, the weak seismic and compliant regions slip aseismically, while the strong seismic regions remain locked, evolving into stress concentrations that fail only in main shocks. The weak seismic areas exhibit most of the interseismic activity and aftershocks but can also creep seismically. This "mixed" frictional behavior can be obtained from a sufficiently heterogenous distribution of the critical slip distance. The model also provides a mechanism for rupture arrest: dynamic rupture fronts decelerate as they penetrate into unloaded complaint or weak seismic areas, producing broad areas of accelerated afterslip. Aftershocks occur on both the weak seismic and compliant areas around a fault, but most of the stress is diffused through aseismic slip. Rapid afterslip on these peripheral areas can also produce aftershocks within the main shock rupture area by reloading weak fault areas that slipped in the main shock and then healed. We test this frictional model by comparing the seismicity and the coseismic slip for the 1966 Parkfield, 1979 Coyote Lake, and 1984 Morgan Hill earthquakes. The interevent seismicity and aftershocks appear to occur on fault areas outside the regions of significant slip: these regions are interpreted as either weak seismic or compliant, depending on whether or not they manifest interevent seismicity.

Boatwright, J.; Cocco, M.

1996-01-01

314

The Work Budget of Rough Faults  

NASA Astrophysics Data System (ADS)

Faults in nature, while generally idealized as planar displacement discontinuities, are indeed rough and non-planar. This roughness is observable over many orders of magnitude across faults that may vary in length from tens of microns to several kilometers. Stress distributions along these rough fault profiles are highly heterogeneous, reflecting the fractal nature of the fault roughness. Here we utilize the boundary element method to model the work budget of frictional slip and opening on synthetic fault profiles generated with known fractal parameters, including the Hurst exponent and the root mean square slope, a measure of roughness amplitude. Energy within the fault models is partitioned into frictional, external, gravitational, seismic, and internal elastic strain energy. Results show that external work, or the work done on the external model boundaries, is smallest for a perfectly planar fault, and steadily increases with increasing roughness amplitude. This pattern is also seen in the internal strain energy, the energy expended in deforming the host rock. The opposite is true for gravitational work, or the work done against gravity in uplifting host rock, as well as with frictional work, the energy dissipated with frictional slip on the fault. These patterns correlate with the decrease in total slip, an increasing number of fault elements experiencing opening, and increasing roughness amplitude of faults. Remarkably, however, for a narrow range of roughness amplitudes which are commonly observed along natural faults, the total work of the system remains approximately constant, while slightly larger than the total work of a planar fault. Faults evolve toward the most mechanically efficient configuration; therefore we argue that this range of roughness amplitudes may act as an energy barrier, preventing faults from removing asperities and evolving to smooth, planar discontinuities.

Newman, P. J.; Griffith, W. A.; Cooke, M. L.

2012-12-01

315

Tracing the Geomorphic Signature of Lateral Faulting  

NASA Astrophysics Data System (ADS)

Active strike-slip faults are among the most dangerous geologic features on Earth. Unfortunately, it is challenging to estimate their slip rates, seismic hazard, and evolution over a range of timescales. An under-exploited tool in strike-slip fault characterization is quantitative analysis of the geomorphic response to lateral fault motion to extract tectonic information directly from the landscape. Past geomorphic work of this kind has focused almost exclusively on vertical motion, despite the ubiquity of horizontal motion in crustal deformation and mountain building. We seek to address this problem by investigating the landscape response to strike-slip faulting in two ways: 1) examining the geomorphology of the Marlborough Fault System (MFS), a suite of parallel strike-slip faults within the actively deforming South Island of New Zealand, and 2) conducting controlled experiments in strike-slip landscape evolution using the CHILD landscape evolution model. The MFS offers an excellent natural experiment site because fault initiation ages and cumulative displacements decrease from north to south, whereas slip rates increase over four fold across a region underlain by a single bedrock unit (Torlesse Greywacke). Comparison of planform and longitudinal profiles of rivers draining the MFS reveals strong disequilibrium within tributaries that drain to active fault strands, and suggests that river capture related to fault activity may be a regular process in strike-slip fault zones. Simple model experiments support this view. Model calculations that include horizontal motion as well as vertical uplift demonstrate river lengthening and shortening due to stream capture in response to shutter ridges sliding in front of stream outlets. These results suggest that systematic variability in fluvial knickpoint location, drainage area, and incision rates along different faults or fault segments may be expected in catchments upstream of strike-slip faults and could act as useful indicators of fault activity.

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

2012-12-01

316

Structural anisotropy of normal fault surfaces  

NASA Astrophysics Data System (ADS)

Precise description of natural fault surfaces is indispensable to understanding the geometry, mechanics and fluid transport properties of faults. Profiles of fault surfaces in the Wasatch fault zone and Oquirrh Mountains, Utah, are measured at 30° increments within the fault plane to determine the directional anisotropy of surface roughness at wavelengths between 10 -3 m and 30 m, and then compared with profiles of larger-scale fault surfaces. Surface anisotropy and an increasing ratio of surface amplitude to wavelength are consistent with self-affine fault topography at wavelengths between 1 mm and approximately 5 km. Fractal dimension of surface profiles generally decreases systematically as the angle to the slip direction increases. Directional anisotropy is described by an azimuthal scaling function ?? = K sin( ?) + ?0 or AF? = ( AFmax -1) sin( ?) + 1, where ?? and AF? are the amplitude to wavelength ratio and anisotropy factor respectively at azimuth ?, measured clockwise relative to slip direction within the fault surface, and ?0 is the amplitude to wavelength ratio parallel to slip direction. K = ( ?90 - ?0) is an anisotropy coefficient and increases systematically with spatial wavelength on the fault surface. Characterization of natural fault surfaces provides parameters such as fractal dimension ( D), intercept (log( C)) of power spectra, profile variance, and variation in anisotropy factor ( AF), which are needed to generate fractal models of natural fault surfaces using spectral synthesis. We generate sample models which illustrate the differences between fault surfaces characterized by constant versus azimuthally varying fractal dimension. The latter model surfaces contain low amplitude corrugations superimposed on elongate ridges which parallel slip direction. This surface texture resembles that of natural fault surfaces that refract across lithologic layering or are cut by secondary faults such as R and R' shears.

Lee, Joong-Jeek; Bruhn, Ronald L.

1996-08-01

317

Has the San Gabriel fault been offset  

SciTech Connect

The San Gabriel fault (SGF) in southern California is a right-lateral, strike-slip fault extending for 85 mi in an arcuate, southwestward-bowing curve from near the San Andreas fault at Frazier Mountain to its intersection with the left-lateral San Antonio Canyon fault (SACF) in the eastern San Gabriel Mountains. Termination of the SGF at the presently active SACF is abrupt and prompts the question Has the San Gabriel Fault been offset. Tectonic and geometric relationships in the area suggest that the SGF has been offset approximately 6 mi in a left-lateral sense and that the offset continuation of the SGF, across the SACF, is the right-lateral, strike-slip San Jacinto fault (SJF), which also terminates at the SACF. Reversing the left-lateral movement on the SACF to rejoin the offset ends of the SGF and SJF reveals a fault trace that is remarkably similar in geometry and movement (and perhaps in tectonic history), to the trace of the San Andreas fault through the southern part of the San Bernardino Mountains. The relationship of the Sierra Madre-Cucamonga fault system to the restored SGF-SJF fault is strikingly similar to the relationship of the Banning fault to the Mission Creek-Mill Creek portion of the San Andreas fault. Structural relations suggest that the San Gabriel-San Jacinto system predates the San Andreas fault in the eastern San Gabriel Mountains and that continuing movement on the SACF is currently affecting the trace of the San Andreas fault in the Cajon Pass area.

Sheehan, J.R.

1988-03-01

318

3D simulation of near-fault strong ground motion: comparison between surface rupture fault and buried fault  

NASA Astrophysics Data System (ADS)

In this paper, near-fault strong ground motions caused by a surface rupture fault (SRF) and a buried fault (BF) are numerically simulated and compared by using a time-space-decoupled, explicit finite element method combined with a multi-transmitting formula (MTF) of an artificial boundary. Prior to the comparison, verification of the explicit element method and the MTF is conducted. The comparison results show that the final dislocation of the SRF is larger than the BF for the same stress drop on the fault plane. The maximum final dislocation occurs on the fault upper line for the SRF; however, for the BF, the maximum final dislocation is located on the fault central part. Meanwhile, the PGA, PGV and PGD of long period ground motions (?1 Hz) generated by the SRF are much higher than those of the BF in the near-fault region. The peak value of the velocity pulse generated by the SRF is also higher than the BF. Furthermore, it is found that in a very narrow region along the fault trace, ground motions caused by the SRF are much higher than by the BF. These results may explain why SRFs almost always cause heavy damage in near-fault regions compared to buried faults.

Liu, Qifang; Yuan, Yifan; Jin, Xing

2007-12-01

319

Fault Diagnosis on Multiple Fault Models by Using Pass/Fail Information  

NASA Astrophysics Data System (ADS)

In general, we do not know which fault model can explain the cause of the faulty values at the primary outputs in a circuit under test before starting diagnosis. Moreover, under Built-In Self Test (BIST) environment, it is difficult to know which primary output has a faulty value on the application of a failing test pattern. In this paper, we propose an effective diagnosis method on multiple fault models, based on only pass/fail information on the applied test patterns. The proposed method deduces both the fault model and the fault location based on the number of detections for the single stuck-at fault at each line, by performing single stuck-at fault simulation with both passing and failing test patterns. To improve the ability of fault diagnosis, our method uses the logic values of lines and the condition whether the stuck-at faults at the lines are detected or not by passing and failing test patterns. Experimental results show that our method can accurately identify the fault models (stuck-at fault model, AND/OR bridging fault model, dominance bridging fault model, or open fault model) for 90% faulty circuits and that the faulty sites are located within two candidate faults.

Takamatsu, Yuzo; Takahashi, Hiroshi; Higami, Yoshinobu; Aikyo, Takashi; Yamazaki, Koji

320

Stacking faults in Si nanocrystals  

SciTech Connect

Si nanocrystals (Si nc) were formed by the implantation of Si{sup +} into a SiO{sub 2} film on (100) Si, followed by high-temperature annealing. High-resolution transmission electron microscopy has been used to examine the microstructure of the Si nc produced by a high-dose (3x10{sup 17} cm{sup -2}) implantation. It is shown that there are only stacking-fault (SF) defects in some nanocrystals; while in others the stacking faults (SFs) coexist with twins. Two kinds of SFs, one being an intrinsic SF, the other being an extrinsic SF, have been observed inside the Si nc. More intrinsic SFs have been found in the Si nc, and the possible reasons are discussed. These microstructural defects are expected to play an important role in the light emission from the Si nc.

Wang, Y.Q.; Smirani, R.; Ross, G.G. [INRS-EMT, 1650, Boulevard Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada)

2005-05-30

321

Perspective View, San Andreas Fault  

NASA Technical Reports Server (NTRS)

The prominent linear feature straight down the center of this perspective view is California's famous San Andreas Fault. The image, created with data from NASA's Shuttle Radar Topography Mission (SRTM), will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, Calif., about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. Two large mountain ranges are visible, the San Gabriel Mountains on the left and the Tehachapi Mountains in the upper right. Another fault, the Garlock Fault lies at the base of the Tehachapis; the San Andreas and the Garlock Faults meet in the center distance near the town of Gorman. In the distance, over the Tehachapi Mountains is California's Central Valley. Along the foothills in the right hand part of the image is the Antelope Valley, including the Antelope Valley California Poppy Reserve. The data used to create this image were acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000.

This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: Varies in a perspective view Location: 34.70 deg. North lat., 118.57 deg. West lon. Orientation: Looking Northwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

2000-01-01

322

Fault trees and imperfect coverage  

NASA Technical Reports Server (NTRS)

A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated exactly. A dynamic state truncation technique is also presented; it produces bounds on the unreliability of the system by considering only part of the state space. Since the model is solved as the state space is generated, the process can be stopped as soon as the desired accuracy is reached.

Dugan, Joanne B.

1989-01-01

323

Superconducting fault-current limiter  

NASA Astrophysics Data System (ADS)

The use of superconductivity to limit fault currents in power systems was examined. The various types of superconducting fault current limiters (SCFCL) were identified through a literature search, then analyzed and compared. The following design parameters were developed: 2.75 ohms, 118 kV (rms, 163 MJ for resistive limiters; 14.5 mH, 110 kV (rms), 8.3 MJ for inductive limiters. The operating characteristics of the resistive SCFCL were derived using transient circuit and heat transfer analysis. Evaluation of SCFCL performance and materials evaluation are discussed. Nb3Sn on a sapphire substrate appears to be the most promising material. No insurmountable obstacles to the development of an SCFCL were revealed. A substantial amount of detailed design and process development will be required before a fully rated module is built for power testing.

1982-02-01

324

Uranium and lanthanides in surficial sediments of Laguna Ojo de Liebre and evaporation ponds of Exportadora de Sal, Guerrero Negro, México.  

NASA Astrophysics Data System (ADS)

To assess uranium and lanthanides behavior in hypersaline environments, surficial sediment samples were taken from Laguna Ojo de Liebre as well as from the evaporation ponds of Exportadora de Sal (the largest natural salt producing facility in the continent). A total of 63 surficial sediment samples from the laguna and 30 samples from the ponds were analyzed by inductive coupled plasma-mass spectrometry for uranium (sediments, deposits and solution) and instrumental neutron activation analysis for REEs in sediments and deposits. Results show that the behavior is all but similar between light and heavy REEs with the exception of Eu which shows a very different pattern of surficial distribution in Laguna Ojo de Liebre with a maximum concentrations in the sediments near the head of the lagoon. Data normalized with North American Shale Composite (NASC) show 3 distinct signature patterns on the surficial sediments, all of them enriched regarding the values of NASC. As for U total content in sediments and solid deposits it shows a higher concentration towards the head of the lagoon (3 mg/kg), from where the water is pumped to the sequence of evaporation ponds, with the lowest values being close to 1 mg/kg near the mouth of the lagoon. The interesting phenomenon begins in the evaporation ponds, where uranium is almost constant in sediments and deposits (0.15-1.5 mg/kg) but behaves conservately in the brine solution, increasing proportionally with salt content (U, 5-20 mg/kg; salt content, 40-250 g/kg). Non lithogenic U was calculated with Sc as reference. Most of the measured U was non lithogenic in the sediments of the lagoon and ponds. The distribution coefficient k= U(non-lith)/U(dis) shows a maximum value at ponds I and II (salt content 40-80 g/kg) decreasing with increasing salinity.

Grajeda-Muñoz, M. M.; Choumiline, E.; Zaposhnikov, D.

2007-05-01

325

Folding above faults, Rocky Mountains  

SciTech Connect

Asymmetric folds formed above basement faults can be observed throughout the Rocky Mountains. Several previous interpretations of the folding process made the implicit assumption that one or both fold hinges migrated or rolled'' through the steep forelimb of the fold as the structure evolved (rolling hinge model). Results of mapping in the Bighorn and Seminoe Mountains, WY, and Sangre de Cristo Range, CO, do not support this hypothesis. An alternative interpretation is presented in which fold hinges remained fixed in position during folding (fixed hinge model). Mapped folds share common characteristics: (1) axial traces of the folds intersect faults at or near the basement/cover interface, and diverge from faults upsection; (2) fold hinges are narrow and interlimb angles cluster around 80--100[degree] regardless of fold location; (3) fold shape is typically angular, despite published cross sections that show concentric folds; and, (4) beds within the folds show thickening and/or thinning, most commonly adjacent to fold hinges. The rolling hinge model requires that rocks in the fold forelimbs bend through narrow fold hinges as deformation progressed. Examination of massive, competent rock units such as the Ord. Bighorn Dolomite, Miss. Madison Limestone, and, Penn. Tensleep Sandstone reveals no evidence of the extensive internal deformation that would be expected if hinges rolled through rocks of the forelimb. The hinges of some folds (e.g. Golf Creek anticline, Bighorn Mountains) are offset by secondary faults, effectively preventing the passage of rocks from backlimb to forelimb. The fixed hinge model proposes that the fold hinges were defined early in fold evolution, and beds were progressively rotated and steepened as the structure grew.

McConnell, D.A. (Univ. of Akron, OH (United States). Dept. of Geology)

1992-01-01

326

Hydrologic, water-quality, and biological assessment of Laguna de las Salinas, Ponce, Puerto Rico, January 2003-September 2004  

USGS Publications Warehouse

The Laguna de Las Salinas is a shallow, 35-hectare, hypersaline lagoon (depth less than 1 meter) in the municipio of Ponce, located on the southern coastal plain of Puerto Rico. Hydrologic, water-quality, and biological data in the lagoon were collected between January 2003 and September 2004 to establish baseline conditions. During the study period, rainfall was about 1,130 millimeters, with much of the rain recorded during three distinct intense events. The lagoon is connected to the sea by a shallow, narrow channel. Subtle tidal changes, combined with low rainfall and high evaporation rates, kept the lagoon at salinities above that of the sea throughout most of the study. Water-quality properties measured on-site (temperature, pH, dissolved oxygen, specific conductance, and Secchi disk transparency) exhibited temporal rather than spatial variations and distribution. Although all physical parameters were in compliance with current regulatory standards for Puerto Rico, hyperthermic and hypoxic conditions were recorded during isolated occasions. Nutrient concentrations were relatively low and in compliance with current regulatory standards (less than 5.0 and 1.0 milligrams per liter for total nitrogen and total phosphorus, respectively). The average total nitrogen concentration was 1.9 milligrams per liter and the average total phosphorus concentration was 0.4 milligram per liter. Total organic carbon concentrations ranged from 12.0 to 19.0 milligrams per liter. Chlorophyll a was the predominant form of photosynthetic pigment in the water. The average chlorophyll a concentration was 13.4 micrograms per liter. Chlorophyll b was detected (detection limits 0.10 microgram per liter) only twice during the study. About 90 percent of the primary productivity in the Laguna de Las Salinas was generated by periphyton such as algal mats and macrophytes such as seagrasses. Of the average net productivity of 13.6 grams of oxygen per cubic meter per day derived from the diel study, the periphyton and macrophyes produced 12.3 grams per cubic meter per day; about 1.3 grams (about 10 percent) were produced by the phytoplankton (plant and algae component of plankton). The total respiration rate was 59.2 grams of oxygen per cubic meter per day. The respiration rate ascribed to the plankton (all organisms floating through the water column) averaged about 6.2 grams of oxygen per cubic meter per day (about 10 percent), whereas the respiration rate by all other organisms averaged 53.0 grams of oxygen per cubic meter per day (about 90 percent). Plankton gross productivity was 7.5 grams per cubic meter per day; the gross productivity of the entire community averaged 72.8 grams per cubic meter per day. Fecal coliform bacteria counts were generally less than 200 colonies per 100 milliliters; the highest concentration was 600 colonies per 100 milliliters.

Soler-Lopez, Luis R.; Gomez-Gomez, Fernando; Rodriguez-Martinez, Jesus

2005-01-01

327

DC superconducting fault current limiter  

NASA Astrophysics Data System (ADS)

There is a lack of satisfying solutions for fault currents using conventional technologies, especially in DC networks, where a superconducting fault current limiter could play a very important part. DC networks bring a lot of advantages when compared to traditional AC ones, in particular within the context of the liberalization of the electric market. Under normal operation in a DC network, the losses in the superconducting element are nearly zero and only a small, i.e. a low cost, refrigeration system is then required. The absence of zero crossing of a DC fault current favourably accelerates the normal zone propagation. The very high current slope at the time of the short circuit in a DC grid is another favourable parameter. The material used for the experiments is YBCO deposited on Al2O3 as well as YBCO coated conductors. The DC limitation experiments are compared to AC ones at different frequencies (50-2000 Hz). Careful attention is paid to the quench homogenization, which is one of the key issues for an SC FCL. The University of Geneva has proposed constrictions. We have investigated an operating temperature higher than 77 K. As for YBCO bulk, an operation closer to the critical temperature brings a highly improved homogeneity in the electric field development. The material can then absorb large energies without degradation. We present tests at various temperatures. These promising results are to be confirmed over long lengths.

Tixador, P.; Villard, C.; Cointe, Y.

2006-03-01

328

Method to identify wells that yield water that will be replaced by water from the Colorado River downstream from Laguna Dam in Arizona and California  

USGS Publications Warehouse

Accounting for the use of Colorado River water is required by the U.S. Supreme Court decree, 1964, Arizona v. California. Water pumped from wells on the flood plain and from certain wells on alluvial slopes outside the flood plain is presumed to be river water and is accounted for as Colorado River water. The accounting-surface method developed for the area upstream from Laguna Dam was modified for use downstream from Laguna Dam to identify wells outside the flood plain of the lower Colorado River that yield water that will be replaced by water from the river. Use of the same method provides a uniform criterion of identification for all users pumping water from wells by determining if the static water-level elevation in the well is above or below the elevation of the accounting surface. Wells that have a static water-level elevation equal to or below the accounting surface are presumed to yield water that will be replaced by water from the Colorado River. Wells that have a static water-level elevation above the accounting surface are presumed to yield river water stored above river level. The method is based on the concept of a river aquifer and an accounting surface within the river aquifer. The river aquifer consists of permeable sediments and sedimentary rocks that are hydraulically connected to the Colorado River so that water can move between the river and the aquifer in response to withdrawal of water from the aquifer or differences in water-level elevations between the river and the aquifer. The subsurface limit of the river aquifer is the nearly impermeable bedrock of the bottom and sides of the basins that underlie the Yuma area and adjacent valleys. The accounting surface represents the elevation and slope of the unconfined static water table in the river aquifer outside the flood plain of the Colorado River that would exist if the river were the only source of water to the river aquifer. The accounting surface was generated by using water-surface profiles of the Colorado River from Laguna Dam to about the downstream limit of perennial flow at Morelos Dam. The accounting surface extends outward from the edges of the flood plain to the subsurface boundary of the river aquifer. Maps at a scale of 1:100,000 show the extent of the river aquifer and elevation of the accounting surface downstream from Laguna Dam in Arizona and California.

Owen-Joyce, Sandra J.; Wilson, Richard P.; Carpenter, Michael C.; Fink, James B.

2000-01-01

329

Fault tolerant operation of switched reluctance machine  

NASA Astrophysics Data System (ADS)

The energy crisis and environmental challenges have driven industry towards more energy efficient solutions. With nearly 60% of electricity consumed by various electric machines in industry sector, advancement in the efficiency of the electric drive system is of vital importance. Adjustable speed drive system (ASDS) provides excellent speed regulation and dynamic performance as well as dramatically improved system efficiency compared with conventional motors without electronics drives. Industry has witnessed tremendous grow in ASDS applications not only as a driving force but also as an electric auxiliary system for replacing bulky and low efficiency auxiliary hydraulic and mechanical systems. With the vast penetration of ASDS, its fault tolerant operation capability is more widely recognized as an important feature of drive performance especially for aerospace, automotive applications and other industrial drive applications demanding high reliability. The Switched Reluctance Machine (SRM), a low cost, highly reliable electric machine with fault tolerant operation capability, has drawn substantial attention in the past three decades. Nevertheless, SRM is not free of fault. Certain faults such as converter faults, sensor faults, winding shorts, eccentricity and position sensor faults are commonly shared among all ASDS. In this dissertation, a thorough understanding of various faults and their influence on transient and steady state performance of SRM is developed via simulation and experimental study, providing necessary knowledge for fault detection and post fault management. Lumped parameter models are established for fast real time simulation and drive control. Based on the behavior of the faults, a fault detection scheme is developed for the purpose of fast and reliable fault diagnosis. In order to improve the SRM power and torque capacity under faults, the maximum torque per ampere excitation are conceptualized and validated through theoretical analysis and experiments. With the proposed optimal waveform, torque production is greatly improved under the same Root Mean Square (RMS) current constraint. Additionally, position sensorless operation methods under phase faults are investigated to account for the combination of physical position sensor and phase winding faults. A comprehensive solution for position sensorless operation under single and multiple phases fault are proposed and validated through experiments. Continuous position sensorless operation with seamless transition between various numbers of phase fault is achieved.

Wang, Wei

330

Fault plane processes and internal architecture of a "strong" paleoseismic fault  

NASA Astrophysics Data System (ADS)

Mature major faults are characterized by high values of displacement/fault thickness resulting by localized repeated slip along the same weakness horizon. A contrasting end-member is a fault where successive slip increments migrate to different discrete shear zone thus resulting in a fault zone with a low displacement/fault thickness ratio (strong fault?). An example of this second type of fault is studied in this work. The Gole Larghe-Val di Genova Fault (GGF) is an exhumed paleoseismic source crosscutting the whole northwestern Adamello batholith (Italian Southern Alps). Fault rocks are an association of indurated proto-ultracataclasites (PUC) and pseudotachylytes (PT). Seismic faulting occurred at 6-8km depth and 250-300^oC. In the studied zone, the GGF accommodates 900m of dextral strike slip displacement over a thickness of 550m. Within the fault displacement is localized into 3 hierarchically different sets of cataclastic horizons (rank 1-3 faults). Rank 1-2 faults nucleated on a pre-existing set of cooling joints. Rank 3 faults form a network of minor fractures newly produced during slip on rank 1-2 faults. Production of pseudotachylytes is usually the last event recorded by each of the GGF faults, and occurs at the host rock/cataclasite boundary. The matrix of PUC contains abundant K-feldspar+epidote+/-chlorite. PT and PUC have a similar chemical composition and are enriched in Loss On Ignition, K_2O, Rb, Ba, U and Fe_2O_3 compared to host rock. This indicates a strong fluid-rock interaction during fault deformation. Field data indicate that each rank 1-2 fault accommodates seismically a "significant" part of slip and, therefore, single faults within GGF were not contemporaneously active. Continuous migration of slip to new deformation horizons is related to the progressive induration of fault rocks during slip by precipitation of K-feldspar+epidote. The spatial evolution of cementation depends on the complex feedback between deformation, permeability and fluid-induced reactions. Progressive cementation enhanced localization within the fault, which finally led to seismic sliding and frictional melting. The production of PT welded the active fault and displacement migrated to nearby joints or less evolved faults of the GGF. The progressive induration and PT welding of the fault rock assemblage explains the bulk low displacement accommodation efficiency of the GGF.

di Toro, G.; Pennacchioni, G.

2003-04-01

331

[Specific diversity and culicidian nuisance in the villages of N'gatty and Allaba in laguna area of Ivory Coast].  

PubMed

Entomological surveys were undertaken between June and December 2006 in N'gatty and Allaba. These villages are located in southern Ivory Coast in a laguna area in Dabou department. In these villages, there are large swampy areas, which have caused the multiplication of anthropophilic Culicidae. Mosquitoes have been collected at preimaginal stage at the time of the larval prospecting and at adult stage through human landing catch. Larval collections have been made using the classic method of "dipping". Larvae have been identified to the genus level. Then, they have been bred in the laboratory to identify adults. Adults collection has been made once a month during three consecutive nights by human landing catch inside houses. Adults have been identified to the specific level. Eight genera of mosquitoes have been collected in these two villages: Aedes, Anopheles, Coquillettidia, Culex, Eretmapodites, Mansonia, Toxorhynchites and Uranotaenia. Twenty-four species have been listed during this stu y. The genus Mansonia is the most predominant with 86% (N = 15,811) and 80% (N = 1,385), respectively, in N'gatty and Allaba. The average biting rate per day varies between N'gatty and Allaba. It is estimated to 308 bites per human per night (b/h/n) in N'gatty and 72 b/h/n in Allaba. In these villages, mosquito nuisance is mainly due to Mansonia with 264 b/h/n and 58 b/h/n, respectively, in N'gatty and Allaba. However, Anopheles gambiae s.l. average rate was 12 b/h/n in N'gatty and 2 b/h/n in Allaba. PMID:20632142

Fofana, D; Konan, K L; Djohan, V; Konan, Y L; Koné, A B; Doannio, J M C; N'goran, K E

2010-12-01

332

Summer feeding ecology of Great Pampa-finches, Embernagra platensis at Laguna de Guaminí, Buenos Aires, Argentina.  

PubMed

The aim of this study was to assemble data on the summer feeding ecology of the Great Pampa-finch, Embernagra platensis at the Laguna de Guaminí, Buenos Aires, Argentina, and to explore the differences related to the dietary patterns for each sex between winter and summer when possible. The stomach contents of 43 birds were analyzed. The animal fraction was composed of Hymenoptera (45.1%), Coleoptera (32.4%), Lepidoptera (6.0%), Araneae (5%) and Orthoptera (3.2%). The application of the index of relative importance (IRI) resulted in 1490.4 for Coleoptera, 428.5 for Hymenoptera and 162.5 for Lepidoptera caterpillars. The vegetal fraction consisted of Triticum aestivum (26.9%), Cyperaceous (25%), Poaceae (Gramineae) (19.3%) and Panicum sp. (11.2%). The IRI values were 893.8 for Triticum aestivum, 174.5 for Gramineae, 126.5 for Panicum sp. and 112.8 for Scirpus sp. The food niche width was 0.33 for both sexes; the diversity index resulted in 1.06 for females and 1.33 for males and specific diversity ranged from 1.87 to 2.84. A canonical component analysis (CCA) was performed on environmental and morphometric variables, and a Monte Carlo test confirmed the canonical correlations. A t-test showed that some birds harmonized with a logarithmic model and some with a geometric curve. During the summer, Embernagra platensis ingests Hymenoptera and Coleoptera more often than seeds, suggesting that two biological mechanisms could be taking place in this bird. PMID:21562695

Ferman, Laura M; Montalti, Diego

2010-09-01

333

[Some attributes of community structure of fishes in Laguna Grande de Obispo, Golfo Cariaco, Sucre State, Venezuela].  

PubMed

Species composition, relative abundance, diversity and community structure of fishes were studied from monthly sampling during December 1995 to November 1996 in the Laguna Grande de Obispo, Gulf of Cariaco, Sucre State, Venezuela. Sampling were realised in 3 stations inside the lagoon with a small beach seine and the other 4 stations with a large beach seine. Seventy four species belonging to 33 families and 68 genera were identified of which 8 species dominated, constituting 90.43% of total catch. Mugil curema, Xenomelaniris brasiliensis, Opistonema oglinum, Atherinomorus stipes and Anchoa hepsetus were present in high abundance in the biomass. M. curema dominated the catch with large seine while X. brasiliensis, M. curema and Eucinostomus argenteus dominated the catch with small seine. Species diversity (H') ranged from 2.968-4.607 bits/ind and species richness of Margalef from 2.752-7.464. An inverse analysis realized on catches by small seine and based on nodal constancy and fidelity allowed to define a pattern of spatial distribution of 9 groups containing 1 to 11 species on the basis their abundance, frequency of appearance and ecological characteristics of each area. An analysis of correlation showed that the salinity, dissolved O2 and precipitation did not show any significant correlation with the ecological parameters studied but existed significant correlation with average surface water temperature (p < 0.05), number of species (S), individuals (N), diversity (H') and species richness (D). The positive correlation was found with surface temperature but no relationship with relative dominance (D1 and D2). The CPUE in biomass did not show any significant association with temperature. PMID:11510425

De Grado, A A; Bashirullah, A

2001-01-01

334

Neotectonics of Panama. I. Major fault systems  

SciTech Connect

The direction and rate of relative plate motion across the Caribbean-Nazca boundary in Panama is poorly known. This lack of understanding can be attributed to diffuse seismicity; lack of well constrained focal mechanisms from critical areas; and dense tropical vegetation. In order to better understand the relation of plate motions to major fault systems in Panama, the authors have integrated geologic, remote sensing, earthquake and UTIG marine seismic reflection data. Three areas of recent faulting can be distinguished in Panama and its shelf areas; ZONE 1 of eastern Panama consists of a 70 km wide zone of 3 discrete left-lateral strike-slip faults (Sanson Hills, Jaque River, Sambu) which strike N40W and can be traced as continuous features for distances of 100-150 km; ZONE 2 in central Panama consists of a diffuse zone of discontinuous normal(.) faults which range in strike from N40E, N70E; ZONE 3 in western Panama consists of a 60 km wide zone of 2 discrete, left-lateral(.) strike-slip faults which strike N60W and can be traced as continuous features for distances of 150 km; ZONE 3 faults appear to be continuous with faults bounding the forearc Teraba Trough of Costa Rica. The relation of faults of ZONE 3 to faults of ZONE 2 and a major fault bounding the southern Panama shelf is unclear.

Corrigan, J.; Mann, P.

1985-01-01

335

Perspective View, San Andreas Fault  

NASA Technical Reports Server (NTRS)

The prominent linear feature straight down the center of this perspective view is the San Andreas Fault in an image created with data from NASA's shuttle Radar Topography Mission (SRTM), which will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, California, about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. This area is at the junction of two large mountain ranges, the San Gabriel Mountains on the left and the Tehachapi Mountains on the right. Quail Lake Reservoir sits in the topographic depression created by past movement along the fault. Interstate 5 is the prominent linear feature starting at the left edge of the image and continuing into the fault zone, passing eventually over Tejon Pass into the Central Valley, visible at the upper left.

This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

Size: Varies in a perspective view Location: 34.78 deg. North lat., 118.75 deg. West lon. Orientation: Looking Northwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

2000-01-01

336

Paleomagnetic Data From the Rinconada Fault in Central California: Evidence for Off-fault Deformation  

NASA Astrophysics Data System (ADS)

The Rinconada fault is one of three major sub-parallel faults of the San Andreas fault system in central California. The fault has 18 km of dextral displacement since the Pliocene and up to 60 km of total displacement for the Tertiary. A fold and thrust best is well developed in Miocene and younger sedimentary rocks on either side of the Rinconada fault. We sampled ~150 sites from the Miocene Monterey Formation within this fold and thrust belt, a unit that is often used in regional paleomagnetic studies. The sites were located within 15 km of the fault trace along a segment of the Rinconada fault that stretches from Greenfield to Paso Robles. Because this unit was deposited while the San Andreas fault system was active at this latitude, any deformation recorded by these rocks is related to plate boundary deformation. Unlike the large (>90°) rotations observed in the Transverse Ranges to the south, vertical axis rotations adjacent to the Rinconada fault are smaller (<15°) and vary with distance from the fault as well as along strike. Thus, the model for rotations from the Transverse Ranges, where large fault-bound panels rotate within a system of conjugate strike-slip faults, does not apply for this region in central California. Instead, we believe rotations occur in small fault blocks and the magnitude of rotation may be affected by local parameters such as fault geometries, specific rock types, and structural complexities. One implication of these vertical axis rotations adjacent to the Riconada fault is that off-fault regions are accommodating some of the fault-parallel plate motion. This is important for our understanding of the partitioning of plate boundary deformation in California.

Crump, S.; Titus, S.; McGuire, Z.; Housen, B. A.

2009-12-01

337

Primary and secondary faulting in the Najd fault system, Kingdom of Saudi Arabia  

USGS Publications Warehouse

The Najd fault system is a major transcurrent (strike-slip) fault system of Proterozoic age in the Arabian Shield. The system is a braided complex of parallel and curved en echelon faults. Complex arrays of secondary structures including strike-slip, oblique-slip, thrust, and normal faults, together with folds and dike swarms, are associated with some major faults, particularly near their terminations. The secondary structures indicate that compressional and extensional and dilational conditions existed synchronously in different parts of the fault zone. The outcrop traces of faults and syntectonic dikes have been used to interpret the configuration of principal compressive stresses during formation of parts of the secondary fracture systems. Second-order deformation was a series of separate events in a complex episodic faulting history. Comparison with model studies indicates that master faults extended in length in stages and periodically developed arrays of secondary structures. Propagation of the major faults took place along splay trajectories, which inter-connected to form a subparallel sheeted and braided zone. Interpretation of the aeromagnetic maps indicates that the Najd system is broader at depth than the outcropping fault complex, and that more continuous structures underlie arrays of faults at surface. The fault pattern is mechanically explicable in terms of simple shear between rigid blocks beneath the exposed structures.

Moore, John McMahon

1979-01-01

338

Just add water and the Colorado River still reaches the sea.  

PubMed

A recent article in Environmental Management by All argued that flood flows in North America's Colorado River do not reach the Gulf of California because they are captured and evaporated in Laguna Salada, a below sea-level lakebed near the mouth of the river. We refute this hypothesis by showing that (1) due to its limited area, the Laguna Salada could have evaporated less than 10% of the flood flows that have occurred since 1989; (2) low flow volumes preferentially flow to the Gulf rather than Laguna Salada; (3) All's method for detecting water surface area in the Laguna Salada appears to be flawed because Landsat Thematic Mapper images of the lakebed show it to be dry when All's analyses said it was flooded; (4) direct measurements of salinity at the mouth of the river and in the Upper Gulf of California during flood flows in 1993 and 1998 confirm that flood waters reach the sea; and (5) stable oxygen isotope signatures in clam shells and fish otoliths recorded the dilution of seawater with fresh water during the 1993 and 1998 flows. Furthermore, All's conclusion that freshwater flows do not benefit the ecology of the marine zone is incorrect because the peer-reviewed literature shows that postlarval larval shrimp populations increase during floods, and the subsequent year's shrimp harvest increases. Furthermore, freshwater flows increase the nursery area for Gulf corvina (Cynoscion othonopterus), an important commercial fish that requires estuarine habitats with salinities in the range of 26-38 per thousand during its natal stages. Although flood flows are now much diminished compared to the pre-dam era, they are still important to the remnant wetland and riparian habitats of the Colorado River delta and to organisms in the intertidal and marine zone. Only a small fraction of the flood flows are evaporated in Laguna Salada. PMID:17546520

Glenn, Edward P; Flessa, Karl W; Cohen, Michael J; Nagler, Pamela L; Rowell, Kirsten; Zamora-Arroyo, Francisco

2007-07-01

339

Networking of Near Fault Observatories in Europe  

NASA Astrophysics Data System (ADS)

Networking of six European near-fault observatories (NFO) was established In the FP7 infrastructure project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation). This networking has included sharing of expertise and know-how among the observatories, distribution of analysis tools and access to data. The focus of the NFOs is on research into the active processes of their respective fault zones through acquisition and analysis of multidisciplinary data. These studies include the role of fluids in fault initiation, site effects, derived processes such as earthquake generated tsunamis and landslides, mapping the internal structure of fault systems and development of automatic early warning systems. The six fault zones are in different tectonic regimes: The South Iceland Seismic Zone (SISZ) in Iceland, the Marmara Sea in Turkey and the Corinth Rift in Greece are at plate boundaries, with strike-slip faulting characterizing the SISZ and the Marmara Sea, while normal faulting dominates in the Corinth Rift. The Alto Tiberina and Irpinia faults, dominated by low- and medium-angle normal faulting, respectively are in the Apennine mountain range in Italy and the Valais Region, characterized by both strike-slip and normal faulting is located in the Swiss Alps. The fault structures range from well-developed long faults, such as in the Marmara Sea, to more complex networks of smaller, book-shelf faults such as in the SISZ. Earthquake hazard in the fault zones ranges from significant to substantial. The Marmara Sea and Corinth rift are under ocean causing additional tsunami hazard and steep slopes and sediment-filled valleys in the Valais give rise to hazards from landslides and liquefaction. Induced seismicity has repeatedly occurred in connection with geothermal drilling and water injection in the SISZ and active volcanoes flanking the SISZ also give rise to volcanic hazard due to volcano-tectonic interaction. Organization among the NERA NFO's has led to their gaining working-group status in EPOS as the WG on Near Fault Observatories, representing multidisciplinary research of faults and fault zones.

Vogfjörd, Kristín; Bernard, Pascal; Chiraluce, Lauro; Fäh, Donat; Festa, Gaetano; Zulficar, Can

2014-05-01

340

POTENTIAL EFFECTS OF FAULTS ON GROUNDWATER FLOW FOR THE YUCCA FLAT BASIN, NEVADA TEST SITE, NEVADA  

Microsoft Academic Search

The permeability changes resulting from finely comminuted material in fault cores and the fractured and brecciated rock in fault damage zones allows faults to channelize groundwater flow along the plane of the fault. The efficiency of faults as permeability structures depends on fault zone width, fault offset, depth at which the fault developed, type of faulted rock, extent of secondary

R. P. Dickerson; W. Fryer

2009-01-01

341

Holocene fault scarps near Tacoma, Washington, USA  

USGS Publications Warehouse

Airborne laser mapping confirms that Holocene active faults traverse the Puget Sound metropolitan area, northwestern continental United States. The mapping, which detects forest-floor relief of as little as 15 cm, reveals scarps along geophysical lineaments that separate areas of Holocene uplift and subsidence. Along one such line of scarps, we found that a fault warped the ground surface between A.D. 770 and 1160. This reverse fault, which projects through Tacoma, Washington, bounds the southern and western sides of the Seattle uplift. The northern flank of the Seattle uplift is bounded by a reverse fault beneath Seattle that broke in A.D. 900-930. Observations of tectonic scarps along the Tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the Puget Sound region.

Sherrod, B. L.; Brocher, T. M.; Weaver, C. S.; Bucknam, R. C.; Blakely, R. J.; Kelsey, H. M.; Nelson, A. R.; Haugerud, R.

2004-01-01

342

Holocene fault scarps near Tacoma, Washington, USA  

NASA Astrophysics Data System (ADS)

Airborne laser mapping confirms that Holocene active faults traverse the Puget Sound metropolitan area, northwestern continental United States. The mapping, which detects forest-floor relief of as little as 15 cm, reveals scarps along geophysical lineaments that separate areas of Holocene uplift and subsidence. Along one such line of scarps, we found that a fault warped the ground surface between A.D. 770 and 1160. This reverse fault, which projects through Tacoma, Washington, bounds the southern and western sides of the Seattle uplift. The northern flank of the Seattle uplift is bounded by a reverse fault beneath Seattle that broke in A.D. 900 930. Observations of tectonic scarps along the Tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the Puget Sound region.

Sherrod, Brian L.; Brocher, Thomas M.; Weaver, Craig S.; Bucknam, Robert C.; Blakely, Richard J.; Kelsey, Harvey M.; Nelson, Alan R.; Haugerud, Ralph

2004-01-01

343

Systems approach to software fault tolerance  

NASA Technical Reports Server (NTRS)

Computing systems are employed for aerospace applications with high reliability requirements. In order to provide the needed reliability, it was necessary to make use of computing systems with fault-tolerance characteristics. Traditionally, fault tolerance is achieved through the use of hardware redundance. However, fault-tolerant techniques based on suitable software design considerations have also been developed. The present paper is concerned with the major issues arising in the context of an application of fault-tolerant software techniques to dynamic systems. Attention is given to fault-tolerant flight software, software component stability, system stability with fault-tolerant software, the preservation of functional performance, N-version vs. recovery blocks in flight software, systems-based software, static and dynamic models, static and dynamic consistency tests, and recovery block initialization.

Caglayan, A. K.; Eckhardt, D. E., Jr.

1985-01-01

344

Performance Analysis on Fault Tolerant Control System  

NASA Technical Reports Server (NTRS)

In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. In this paper, an FTC analysis framework is provided to calculate the upper bound of an induced-L(sub 2) norm of an FTC system with existence of false identification and detection time delay. The upper bound is written as a function of a fault detection time and exponential decay rates and has been used to determine which FTC law produces less performance degradation (tracking error) due to false identification. The analysis framework is applied for an FTC system of a HiMAT (Highly Maneuverable Aircraft Technology) vehicle. Index Terms fault tolerant control system, linear parameter varying system, HiMAT vehicle.

Shin, Jong-Yeob; Belcastro, Christine

2005-01-01

345

In-circuit fault injector user's guide  

NASA Technical Reports Server (NTRS)

A fault injector system, called an in-circuit injector, was designed and developed to facilitate fault injection experiments performed at NASA-Langley's Avionics Integration Research Lab (AIRLAB). The in-circuit fault injector (ICFI) allows fault injections to be performed on electronic systems without special test features, e.g., sockets. The system supports stuck-at-zero, stuck-at-one, and transient fault models. The ICFI system is interfaced to a VAX-11/750 minicomputer. An interface program has been developed in the VAX. The computer code required to access the interface program is presented. Also presented is the connection procedure to be followed to connect the ICFI system to a circuit under test and the ICFI front panel controls which allow manual control of fault injections.

Padilla, Peter A.

1987-01-01

346

Software reliability through fault-avoidance and fault-tolerance  

NASA Technical Reports Server (NTRS)

The use of back-to-back, or comparison, testing for regression test or porting is examined. The efficiency and the cost of the strategy is compared with manual and table-driven single version testing. Some of the key parameters that influence the efficiency and the cost of the approach are the failure identification effort during single version program testing, the extent of implemented changes, the nature of the regression test data (e.g., random), and the nature of the inter-version failure correlation and fault-masking. The advantages and disadvantages of the technique are discussed, together with some suggestions concerning its practical use.

Vouk, Mladen A.; Mcallister, David F.

1990-01-01

347

Identifiability of Additive Actuator and Sensor Faults by State Augmentation  

NASA Technical Reports Server (NTRS)

A class of fault detection and identification (FDI) methods for bias-type actuator and sensor faults is explored in detail from the point of view of fault identifiability. The methods use state augmentation along with banks of Kalman-Bucy filters for fault detection, fault pattern determination, and fault value estimation. A complete characterization of conditions for identifiability of bias-type actuator faults, sensor faults, and simultaneous actuator and sensor faults is presented. It is shown that FDI of simultaneous actuator and sensor faults is not possible using these methods when all sensors have unknown biases. The fault identifiability conditions are demonstrated via numerical examples. The analytical and numerical results indicate that caution must be exercised to ensure fault identifiability for different fault patterns when using such methods.

Joshi, Suresh; Gonzalez, Oscar R.; Upchurch, Jason M.

2014-01-01

348

Fluids and the Heart Mountain fault revisited  

Microsoft Academic Search

Stable isotopic results from the Heart Mountain fault in northwestern Wyoming show that fluids migrated along the detachment during faulting. We report herein calcite (delta18O and delta13C values in fault breccias, shifted by as much as -150\\/00o (relative to SMOW) and -50\\/00o (relative to PDB), respectively, which demonstrate focusing of meteoric waters along the detachment. The isotopic depletions systematically increase

Alexis S. Templeton; James Sweeney Jr.; Hans Manske; Jennifer Fox Tilghman; Adam Violich; C. Page Chamberlain

1995-01-01

349

Hydrogen Embrittlement And Stacking-Fault Energies  

NASA Technical Reports Server (NTRS)

Embrittlement in Ni/Cu alloys appears related to stacking-fault porbabilities. Report describes attempt to show a correlation between stacking-fault energy of different Ni/Cu alloys and susceptibility to hydrogen embrittlement. Correlation could lead to more fundamental understanding and method of predicting susceptibility of given Ni/Cu alloy form stacking-fault energies calculated from X-ray diffraction measurements.

Parr, R. A.; Johnson, M. H.; Davis, J. H.; Oh, T. K.

1988-01-01

350

Theory of fault-tolerant quantum computation  

Microsoft Academic Search

In order to use quantum error-correcting codes to improve the performance of a quantum computer, it is necessary to be able to perform operations fault-tolerantly on encoded states. I present a theory of fault-tolerant operations on stabilizer codes based on symmetries of the code stabilizer. This allows a straightforward determination of which operations can be performed fault-tolerantly on a given

Daniel Gottesman

1998-01-01

351

Fault location using digital relay data  

SciTech Connect

Power transmission lines form the backbone of electric utility operations. Individual lines may suffer short-circuit faults and must be switched out of the network by protective relays and power circuit breakers located in the terminating substations. Modern microprocessor-based relays are the brains of the line protection system, sampling and analyzing voltage and current signals from the line and making decisions to trip the breakers within tens of milliseconds when a fault occurs. The crew must find and fix the problem along a right-of-way that may be long or difficult to access. For some extra-high-voltage (EHV) lines, especially near generating plants, automatic reclosing of breakers cannot be used. Every fault trip requires inspection around the fault location by a maintenance crew before the line can be manually re-energized. This adversely impacts service reliability and operating costs, which are major concerns in today`s competitive and cost-conscious utility business environment. There is a tremendous cost benefit in having data-processing tools that analyze the saved fault voltage and current signals to deduce accurately the physical location of the fault on the line; the crew can travel directly to the site of the problem and take quick action. Accurate fault location also helps distinguish between random lightning-induced faults occurring close together versus a recurrent fault location resulting from a marginally contaminated insulator, a swaying or growing tree, or a fire under the line. This article presents new calculations that do not require synchronization of the records to achieve excellent accuracy. Following an overview of the technical problems in computing fault location from fault voltage and current signals, a sampling of the newest and most accurate techniques that are easily implemented in existing digital devices for calculating location from one-ended or two-ended line fault data records is given.

Novosel, D.; Hart, D.G. [ABB Transmission Technology Inst., Raleigh, NC (United States)] [ABB Transmission Technology Inst., Raleigh, NC (United States); Udren, E. [ABB Relay Div., Coral Springs, FL (United States)] [ABB Relay Div., Coral Springs, FL (United States); Saha, M.M.

1995-07-01

352

Negative Selection Algorithm for Aircraft Fault Detection  

Microsoft Academic Search

We investigated a real-valued Negative Selection Algorithm (NSA) for fault detection in man-in-the-loop aircraft operation. The de- tection algorithm uses body-axes angular rate sensory data exhibiting the normal flight behavior patterns, to generate probabilistically a set of fault detectors that can detect any abnormalities (including faults and damages) in the behavior pattern of the aircraft flight. We performed experiments with

D. Dasgupta; K. Krishnakumar; D. Wong; M. Berry

2004-01-01

353

Sequential testing algorithms for multiple fault diagnosis  

Microsoft Academic Search

We consider the problem of constructing optimal and near-optimal test sequences for multiple fault diagnosis. The computational complexity of solving the optimal multiple-fault isolation problem is super exponential, that is, it is much more difficult than the single-fault isolation problem, which, by itself, is NP-hard. By employing concepts from information theory and AND\\/OR graph search and by exploiting the single

Mojdeh Shakeri; Vijaya Raghavan; Krishna R. Pattipati; Ann Patterson-hine

2000-01-01

354

Classification of Aircraft Maneuvers for Fault Detection  

Microsoft Academic Search

Ensemble classifiers tend to outperform their component base classifiers when the training data are subject to variability.\\u000a This intuitively makes ensemble classifiers useful for application to the problem of aircraft fault detection. Automated fault\\u000a detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection\\u000a assume the availability of data produced during all possible faulty

Nikunj C. Oza; Kagan Tumer; Irem Y. Tumer; Edward M. Huff

2003-01-01

355

Diagnosing Multiple Faults in SSM\\/PMAD  

Microsoft Academic Search

This paper discusses multiple fault diagnosis for SSM\\/PMAD using the Knowledge Management Design System as applied to the SSM\\/PMAD domain ( KNOMAD-SSM\\/PMAD). KNOMAD-SSM\\/PMAD provides a powerful facility for knowledge representation and re* soning which has been used to build the second generation of FRAMES (Fault Recovery and Management Expert System). FRAMES now handles the diagnosis of multiple faults as well

Joel Riedesel

1990-01-01

356

DC zonal electrical system fault isolation and reconfiguration  

Microsoft Academic Search

Fault isolation and re-configuration on a DC bus distributed through an electrical system is studied. This paper builds upon previously proposed zonal architectures that ensure power continuity during a fault and isolation of a fault with minimal impact to un-faulted portions of the system. The approach utilizes no load switches for fault isolation aided by multiple power electronic converters feeding

Rob Cuzner; Aaron Jeutter

2009-01-01

357

Geometric and rheological asperities in an exposed fault zone  

Microsoft Academic Search

Earthquake dynamics are strongly affected by fault zone structure and fault surface geometry. Here we investigate the interplay of bulk deformation and surface topography using detailed structural analysis of a fault zone near Klamath Falls, Oregon, combined with LiDAR measurements of the fault surface. We find that the fault zone has a layered damage architecture. Slip primarily occurs inside a

Amir Sagy; Emily E. Brodsky

2009-01-01

358

Polyscale, polymodal fault geometries: evolution and predictive capability  

NASA Astrophysics Data System (ADS)

The Late Permian Rangal coal measures on the edge of the Nebo synclinorium in the Bowen basin, NE Queensland, Australia, are cut by normal faults. Mining operations allow 13 faults to be mapped in some detail to depths of 200m. These faults cut Tertiary intrusions and a reverse fault as well as the coal seams, and show no obvious signs of reactivation. The steeply dipping faults are clustered into groups of two to four, separated by hundreds of meters. The faults trend ENE and NE; both trends of faults dip in both directions, defining a quadrimodal geometry. The odd axis construction for these faults suggests that vertical shortening was accompanied by horizontal extension along both principal directions of 153° and 063°. The mapped extents of the faults are limited by erosion and the depth to which the faults have been drilled, but displacement profiles along the lengths of the faults show maxima within the fault planes. The displacement profiles suggest that the currently mapped faults have similar lengths to the total preserved lengths of the faults, and that they will continue into the unmined ground to a limited, but predictable extent. The fault planes have a complex geometry, with segments of individual faults showing a similar variability in orientation to the ensemble of fault planes: the fault planes themselves are polymodal. Displacement profiles show a good correlation with segment orientation. An odd axis construction based on fault segments, rather than individual faults, gives principal extension directions within 4° of the above results. The variable orientation of fault segments, the correlation of the displacement profiles with fault orientation, and the similarity between the segment and ensemble fault kinematics suggest that the faults have evolved by propagation and linking of smaller polymodal faults in the same bulk strain field.ross section of polymodal fault at Hail Creek coal mine

Blenkinsop, T. G.; Carvell, J.; Clarke, G.; Tonelli, M.

2012-12-01

359

Scaling of fault damage zones with displacement and the implications for fault growth processes  

NASA Astrophysics Data System (ADS)

Knowledge of the spatial extent of damage surrounding fault zones is important for understanding crustal fluid flow and also for understanding the physical processes and mechanics by which fault zones develop with slip. There are few data available on the scaling of the fault damage zone with fault displacement, and of those that exist, deriving scaling relationships is hampered by comparing faults that run through different lithologies, have formed at different crustal depths or tectonic regimes (e.g., normal versus strike-slip movement). We describe new data on the microfracture damage zone width from small displacement fault zones within the Atacama fault zone in northern Chile that formed at ˜6 km depth within a dioritic protolith. The microfracture damage zone is shown by an alteration halo surrounding the faults in which the density of the microfractures is much greater than background levels in the undeformed protolith. The data show that damage zone width increases with fault displacement and there appears to be a zero intercept to this relationship, meaning that at zero displacement, there is no microfracture damage zone. This is supported by field observations at fault tips that show a tapering out of fault damage zones. These data, combined with data from the literature, indicate that this same relationship might hold for much larger displacement faults. There is also a distinct asymmetry to the fracture damage. Several processes for the development of the observed scaling are discussed. The widely accepted theory of a process zone predicts that fault damage zone width increases with fault length and thus should always be largest at a propagating fault tip where displacement is lowest. This prediction is opposite to that seen in the current data set, leading to suggestion that other processes, such as damage zone growth with increasing displacement due to geometric irregularities or coseismic damage formation might better explain the spatial extent of damage surrounding even low-displacement faults.

Faulkner, D. R.; Mitchell, T. M.; Jensen, E.; Cembrano, J.

2011-05-01

360

The Coseismic Fault Weakening Processes Inferred from Frictional and Transport Properties of Fault Rocks, TCDP  

Microsoft Academic Search

Faults weaken during coseismic slip, and many factors affect the weakening process. Among these are the frictional properties and permeability of fault-consisting materials. The Taiwan Chelungpu-fault Drilling Project recovered cores from 500 m to 2000 m depth, penetrating several distinct major fault planes that are likely the slip planes from the 1999 Chi-Chi Earthquake (Ma et al., 2006). We measured

Hiroki Sone; Hiroyuki Noda; Toshihiko Shimamoto

2007-01-01

361

Variations in Frictional Behavior of Fault Gouge Along a low Angle Normal Fault System  

Microsoft Academic Search

The Panamint Valley fault system contributes up to ~2.0 mm\\/yr of slip to the Eastern California Shear Zone, and has been interpreted to have developed as a low-angle detachment system. More recent studies of young scarps suggest that the fault currently accommodates oblique normal slip. Recognizing the complications in explaining low angle normal faulting using classic fault mechanics we investigate

T. Numelin; C. Marone; E. Kirby

2003-01-01

362

Simulated fault injection: a methodology to evaluate fault tolerant microprocessor architectures  

Microsoft Academic Search

A simulation-based fault-injection methodology for validating fault-tolerant microprocessor architectures is described. The approach uses mixed-mode simulation (electrical\\/logic analysis), and injects transient errors in run-time to assess the resulting fault-impact. To exemplify the methodology, a fault-tolerant architecture which models the digital aspects of a dual-channel, real-time jet-engine controller is used. The level of effectiveness of the dual configuration with respect to

Gwan S. Choi; Ravishankar K. Iyer; Victor A. Carreno

1990-01-01

363

Faults Discovery By Using Mined Data  

NASA Technical Reports Server (NTRS)

Fault discovery in the complex systems consist of model based reasoning, fault tree analysis, rule based inference methods, and other approaches. Model based reasoning builds models for the systems either by mathematic formulations or by experiment model. Fault Tree Analysis shows the possible causes of a system malfunction by enumerating the suspect components and their respective failure modes that may have induced the problem. The rule based inference build the model based on the expert knowledge. Those models and methods have one thing in common; they have presumed some prior-conditions. Complex systems often use fault trees to analyze the faults. Fault diagnosis, when error occurs, is performed by engineers and analysts performing extensive examination of all data gathered during the mission. International Space Station (ISS) control center operates on the data feedback from the system and decisions are made based on threshold values by using fault trees. Since those decision-making tasks are safety critical and must be done promptly, the engineers who manually analyze the data are facing time challenge. To automate this process, this paper present an approach that uses decision trees to discover fault from data in real-time and capture the contents of fault trees as the initial state of the trees.

Lee, Charles

2005-01-01

364

Applications of Fault Detection in Vibrating Structures  

NASA Technical Reports Server (NTRS)

Structural fault detection and identification remains an area of active research. Solutions to fault detection and identification may be based on subtle changes in the time series history of vibration signals originating from various sensor locations throughout the structure. The purpose of this paper is to document the application of vibration based fault detection methods applied to several structures. Overall, this paper demonstrates the utility of vibration based methods for fault detection in a controlled laboratory setting and limitations of applying the same methods to a similar structure during flight on an experimental subscale aircraft.

Eure, Kenneth W.; Hogge, Edward; Quach, Cuong C.; Vazquez, Sixto L.; Russell, Andrew; Hill, Boyd L.

2012-01-01

365

Sequential Test Strategies for Multiple Fault Isolation  

NASA Technical Reports Server (NTRS)

In this paper, we consider the problem of constructing near optimal test sequencing algorithms for diagnosing multiple faults in redundant (fault-tolerant) systems. The computational complexity of solving the optimal multiple-fault isolation problem is super-exponential, that is, it is much more difficult than the single-fault isolation problem, which, by itself, is NP-hard. By employing concepts from information theory and Lagrangian relaxation, we present several static and dynamic (on-line or interactive) test sequencing algorithms for the multiple fault isolation problem that provide a trade-off between the degree of suboptimality and computational complexity. Furthermore, we present novel diagnostic strategies that generate a static diagnostic directed graph (digraph), instead of a static diagnostic tree, for multiple fault diagnosis. Using this approach, the storage complexity of the overall diagnostic strategy reduces substantially. Computational results based on real-world systems indicate that the size of a static multiple fault strategy is strictly related to the structure of the system, and that the use of an on-line multiple fault strategy can diagnose faults in systems with as many as 10,000 failure sources.

Shakeri, M.; Pattipati, Krishna R.; Raghavan, V.; Patterson-Hine, Ann; Kell, T.

1997-01-01

366

Fault-tolerant policies for optical grid  

NASA Astrophysics Data System (ADS)

Optical Grid has been thought as a promising technology to support large-scale data-intensive distributed applications. For such a system with so many heterogeneous resources involved, faults seem to be inevitable. A fault in Optical Grid may lead to the failure of the application. Therefore, fault-tolerant policies are necessary to improve the performance of Optical Grid and satisfy the SLA requirements of the applications. In this paper, we propose several fault-tolerant policies for Optical Grid. The performances of different polices are compared by simulation.

Guo, Wei; Jin, Yaohui; Sun, Weiqiang; Hu, Weisheng

2008-11-01

367

Lake records of Northern Hemisphere South American summer monsoon variability from the Cordillera Oriental, Colombia: Initial results from Lago de Tota and Laguna de Ubaque  

NASA Astrophysics Data System (ADS)

The lack of terrestrial paleoclimate records from the Northern Hemisphere Andes with decadal resolution has meant that our understanding of abrupt South American summer monsoon (SASM) variability during the Holocene is almost exclusively based on data from Southern Hemisphere sites. In order to develop a more integrated and complete picture of the SASM as a system and its response during rapid climate changes, high-resolution paleoclimate records are needed from the Northern Hemisphere Andes. We present initial results from analysis of lake sediment cores that were collected from Lago de Tota (N 5.554, W 72.916) and Laguna de Ubaque (N 4.500, W 73.935) in the Eastern Cordillera of the Colombian Andes. These sediment cores were collected in July 2013 as part on an ongoing paleoclimate research initiative in Colombia. Located in the Boyacá Provence, Lago de Tota is the largest high-altitude lake (3010 masl) in the Northern Hemisphere Andes and the second largest Andean lake in South America. As such, hydrologic changes recorded in the lake's sediment record reflect regional climate responses. Lago de Ubaque (2070 masl) is a small east facing moraine-dammed lake near the capital of Bogotá that contains finely laminated clastic sediments. The initial sedimentological and chronological results demonstrate that Lago de Tota and Laguna de Ubaque have excellent potential for resolving Northern Hemisphere SASM variability at decadal time scales or better. Such records will provide important counterparts to high-resolution paleoclimate records from the Southern Hemisphere Andes.

Escobar, J.; Rudloff, O.; Bird, B. W.

2013-12-01

368

Software reliability through fault-avoidance and fault-tolerance  

NASA Technical Reports Server (NTRS)

Strategies and tools for the testing, risk assessment and risk control of dependable software-based systems were developed. Part of this project consists of studies to enable the transfer of technology to industry, for example the risk management techniques for safety-concious systems. Theoretical investigations of Boolean and Relational Operator (BRO) testing strategy were conducted for condition-based testing. The Basic Graph Generation and Analysis tool (BGG) was extended to fully incorporate several variants of the BRO metric. Single- and multi-phase risk, coverage and time-based models are being developed to provide additional theoretical and empirical basis for estimation of the reliability and availability of large, highly dependable software. A model for software process and risk management was developed. The use of cause-effect graphing for software specification and validation was investigated. Lastly, advanced software fault-tolerance models were studied to provide alternatives and improvements in situations where simple software fault-tolerance strategies break down.

Vouk, Mladen A.; Mcallister, David F.

1993-01-01

369

Pore fluid and seismogenic characteristics of fault rock at depth on the Wasatch Fault, Utah  

Microsoft Academic Search

Fluid inclusions and structural fabric in fault rock in the exhumed footwall of the Wasatch fault allow measurement of fluid pressure, temperature, and composition and estimation of rheological characteristics of fault behavior. Hydrothermally altered and deformed Oligocene quartz monzonite of the Little Cottonwood stock forms a partially preserved footwall carapace at the southern end of the Salt Lake segment of

W. T. Parry; R. L. Bruhn

1986-01-01

370

FAULT LOCATION FOR RADIAL DISTRIBUTION SYSTEMS USING FAULT GENERATED HIGH-FREQUENCY TRANSIENTS AND WAVELET ANALYSIS  

Microsoft Academic Search

Fault location in radial distribution Systems can be divided into two important steps. The first is to identify the fault branch and the second one is to determine the location of the fault in the faulty branch. It is rarely less papers in the field of faulty branch identification. In this paper a new method based on previous works is

Davood JALALI; Niki MOSLEMI

2005-01-01

371

LATE QUATERNARY FAULTING AND THERMOLUMINESCENCE DATING OF THE EAST CACHE FAULT ZONE, NORTH-CENTRAL UTAH  

Microsoft Academic Search

The East Cache fault zone (ECFZ), the southernmost of five en-echelon Quaternary normal faults between the Wasatch and Teton faults, dis- plays evidence of two large paleoearthquakes in the last 15,000 years (15 ka). Stratigraphic data from a trench on the central segment of the ECFZ are augmented with one radiocarbon date, the regional radiocar- bon chronology, and 14 thermoluminescence

JAMES MCCALPIN; S. L. FORMAN

1991-01-01

372

Fault-Tolerant Structure and Modulation Strategies With Fault Detection Method for Matrix Converters  

Microsoft Academic Search

This paper proposes a fault-tolerant matrix converter with reconfigurable structure and modified switch control schemes, along with a fault diagnosis technique for open-circuited switch failures. The proposed fault recognition method can detect and locate a failed bidirectional switch with voltage error signals dedicated to each switch, based on a direct comparison of the input and the output voltages. Following the

Sangshin Kwak

2010-01-01

373

Fault Injection into VHDL Models: Experimental Validation of a Fault Tolerant Microcomputer System  

Microsoft Academic Search

This work presents a campaign of fault injection to validate the dependability of a fault tolerant microcomputer system. The system is duplex with cold stand-by sparing, parity detection and a watchdog timer. The faults have been injected on a chip-level VHDL model, using an injection tool designed with this purpose. We have carried out a set of injection experiments (with

Daniel Gil; R. Martínez; J. V. Busquets; Juan Carlos Baraza; Pedro J. Gil

1999-01-01

374

A fault diagnosis scheme for time-varying fault using output probability density estimation  

Microsoft Academic Search

In this paper, a fault diagnosis scheme for a class of time-varying faults using output probability density estimation is presented. The system studied is a nonlinear system with time delays. The measured output is viewed as a stochastic process and its probability density function (PDF) is modeled, which leads to a deterministic dynamical model including nonlinearities, uncertainties. The fault considered

Yumin Zhang; Qing-Guo Wang; Kai-Yew Lum

2008-01-01

375

A desktop environment for assessment of fault diagnosis based fault tolerant flight control laws  

Microsoft Academic Search

We present a simulation based software environment conceived to allow an easy assessment of fault diagnosis based fault tolerant control techniques. The new tool is primary intended for the development of advanced flight control applications with fault accommodation abilities, where the requirements for increased autonomy and safety play a premier role.

Simon Hecker; Andras Varga; Gertjan Looye

2008-01-01

376

Guided Waves from Sources Outside Faults: An Indication for Shallow Fault Zone Structure?  

Microsoft Academic Search

— Using 3-D numerical modeling of seismic wave propagation we investigate the possibility of generating fault zone (FZ) trapped wave energy from sources well outside a fault. The FZ is represented by a O(200 m) wide vertical low velocity layer in a half space. We find that FZ trapped waves can be excited from sources well outside the fault if

Miko Fohrmann; Heiner Igel; Gunnar Jahnke; Yehuda Ben-Zion

2004-01-01

377

Permeability of fault-related rocks, and implications for hydraulic structure of fault zones  

Microsoft Academic Search

The permeability structure of a fault zone in granitic rocks has been investigated by laboratory testing of intact core samples from the unfaulted protolith and the two principal fault zone components; the fault core and the damaged zone. The results of two test series performed on rocks obtained from outcrop are reported. First, tests performed at low confining pressure on

J. Goddard; C. Forster

1997-01-01

378

Surface roughness of ancient seismic faults exhumed from seismogenic depths (Gole Larghe Fault, Italian Alps)  

Microsoft Academic Search

Fault surface roughness is a principal factor controlling earthquake rupture nucleation, propagation and arrest, and, possibly, dynamic friction during seismic slip. However, the characterization of fault roughness is limited to a few examples of fault zones exhumed from <5 km depth and generally hosted in sedimentary and volcanic lithologies. Here we investigate the roughness of slip surfaces from the seismogenic

Andrea Bistacchi; William Ashley Griffith; Stefan Nielsen; Steven A. Smith; Giulio di Toro

2010-01-01

379

Normal Fault-Related Surface Monoclines: 3-D Developmental Controls and Implications for Fault Evolution  

Microsoft Academic Search

Fault-related folds are usually described in sedimentary sequences but surface folds are also associated with normal faults in volcanic rocks erupted at divergent plate boundaries or in continental rift zones. At the active plate boundary in SW Iceland, normal fault traces in basalt lava flows are commonly marked at the surface by laterally continuous, narrow monoclinal flexures that formed above

N. D. Boersma; S. A. Kattenhorn

2006-01-01

380

Earthquake Hazard and Segmented Fault Evolution, Hat Creek Fault, Northern California  

Microsoft Academic Search

Precise insight into surface rupture and the evolution and mechanical interaction of segmented normal fault systems is critical for assessing the potential seismic hazard. The Hat Creek fault is a ~35 km long, NNW trending segmented normal fault system located on the western boundary of the Modoc Plateau and within the extending backarc basin of the Cascadia subduction zone in

M. W. Blakeslee; S. A. Kattenhorn

2010-01-01

381

A novel KFCM based fault diagnosis method for unknown faults in satellite reaction wheels.  

PubMed

Reaction wheels are one of the most critical components of the satellite attitude control system, therefore correct diagnosis of their faults is quintessential for efficient operation of these spacecraft. The known faults in any of the subsystems are often diagnosed by supervised learning algorithms, however, this method fails to work correctly when a new or unknown fault occurs. In such cases an unsupervised learning algorithm becomes essential for obtaining the correct diagnosis. Kernel Fuzzy C-Means (KFCM) is one of the unsupervised algorithms, although it has its own limitations; however in this paper a novel method has been proposed for conditioning of KFCM method (C-KFCM) so that it can be effectively used for fault diagnosis of both known and unknown faults as in satellite reaction wheels. The C-KFCM approach involves determination of exact class centers from the data of known faults, in this way discrete number of fault classes are determined at the start. Similarity parameters are derived and determined for each of the fault data point. Thereafter depending on the similarity threshold each data point is issued with a class label. The high similarity points fall into one of the 'known-fault' classes while the low similarity points are labeled as 'unknown-faults'. Simulation results show that as compared to the supervised algorithm such as neural network, the C-KFCM method can effectively cluster historical fault data (as in reaction wheels) and diagnose the faults to an accuracy of more than 91%. PMID:22035775

Hu, Di; Sarosh, Ali; Dong, Yun-Feng

2012-03-01

382

GEOMECHANICAL AND MICROSTRUCTURAL PROPERTIES OF SILICICLASTIC FAULT ROCKS AND THEIR IMPACT ON PREDICTION OF FAULT REACTIVATION  

Microsoft Academic Search

Fault seal prediction has become one of the most important considerations in petroleum exploration in recent years. This has been the result of intensive research from seismic to core to micro scale and has resulted in such developments as robust fault juxtaposition analysis diagrams and an understanding of the microscale processes that result in fault rock development. Well constrained lithological

David N. Dewhurst; Richard R. Hillis; Richard M. Jones; Scott D. Mildren; Adelaide Terrace

2002-01-01

383

Lightning faults on distribution lines  

SciTech Connect

Until now, power engineers have been unable to quantify electrical system outages and damage caused by lightning. Determining the number of lightning strikes to overhead lines is a necessary first step in evaluating design options for lightning protection systems. Under contract to the Electric Power Research Institute (EPRI), the authors have developed low-cost instrumentation by lightning and those caused by other phenomena. The theories used to develop this coincident lightning events detector (CLED), the experiment design used for testing the CLED, and the test results are discussed. Shielding from nearby structures were found to be a major consideration in assessing the lightning fault rate on distribution lines.

Parrish, D.E.; Kvaltine, D.J. (CH2M Hill, Gainesville, FL (US))

1989-10-01

384

MEFISTO-L: A VHDL-Based Fault Injection Tool for the Experimental Assessment of Fault Tolerance  

Microsoft Academic Search

The early assessment of the adequacy of fault tolerance mechanisms (FTMs), and the subsequent removal of fault tolerance deficiency faults (ftd-faults), are essential tasks in the design process of dependable computer systems. The paper is centered on the description and application of the features of MEFISTO-L, the fault injection tool for VHDL models, being developed at LAAS for supporting the

Jérome Boué; Philippe Pétillon; Yves Crouzet

1998-01-01

385

An Accurate Fault Locator with Compensation for Apparent Reactance in the Fault Resistance Resulting from Remote-End Infeed  

Microsoft Academic Search

A microprocessor based fault locator is described, which uses novel compensation techniques to improve accuracy. It displays the distance to the fault in percent of transmission line length, for facilitating repair and restoration following a permanent fault. Also, it pinpoints weak spots following transient faults. This new method for fault location on electric power transmission lines uses recorded phase currents

Leif Eriksson; Murari Mohan Saha; G. D. Rockefeller

1985-01-01

386

Fault geometry and segmentation of the MTL active fault system in the Iyo_|nada Sea, western Shikoku, in Japan  

Microsoft Academic Search

The Median Tectonic Line (MTL) active fault system is one of the most active fault system in Japan, which is an east-west trending, 190 km-long fault system and consists of several rupture segments in Shikoku. A long active fault system such as the MTL active fault system may not rupture along its entire length in a single earthquake but instead

M. Ikeda; F. Nanayama; K. Miura; K. Outsuka; S. Kobayashi; Y. Ohno; S. Kanayama; T. Hasegawa; Y. Sugiyama; E. Tsukuda

2002-01-01

387

Moderately High Holocene Rate of Slip on the Western Garlock Fault Favors a Conjugate Fault Model  

NASA Astrophysics Data System (ADS)

The precise tectonic role of the left-lateral Garlock fault in southern California has been controversial. Three tectonic models that have been previously proposed in the literature yield significantly different predictions for the slip rate, history, orientation and total bedrock offset as a function of distance along strike. In an effort to test these models, I present the first slip-rate estimate for the western Garlock fault that is constrained by radiocarbon dating. The site is located 18 km northeast of the town of Mojave, and 3.5 km southwest of the point where Lone Tree Canyon crosses the fault. A channel (referred to here as Clark Wash) incised into a latest Pleistocene alluvial fan has been left-laterally offset at least 66 ± 6 m and no more than 100 meters across the western Garlock fault, indicating a left-lateral slip rate of 7.6 mm/yr (95 % confidence interval of 5.3-10.7 mm/yr) using bracketing dendrochronologically calibrated radiocarbon dates. Vertical slip has been negligible on the Garlock fault at Clark Wash during the Holocene. A few hundred meters to the north, however, the westward continuation of the central Garlock fault strand appears to be expressed as an active normal fault at the southern range front of the Sierra Nevada with a Holocene to latest Pleistocene dip-slip rate of 0.4-0.7 mm/yr. The relatively high left-lateral slip rate determined here indicates that the western segment of the Garlock fault shows a similar rate of Holocene movement to the central Garlock fault. The moderately high rate of motion on the western Garlock fault is most consistent with a model in which the Garlock fault (or at least the western Garlock fault) acts as a conjugate shear to the San Andreas system. Models in which left-slip on the Garlock fault accommodates extension north of the fault are problematic because present-day (geodetic) deformation reveals little or no Garlock-parallel extension north of the Garlock fault, and older strain markers yield an extension direction that is more closely parallel to some of the right-lateral faults north of the Garlock than to any segment of the Garlock fault. The western Garlock fault, in particular, is at a high angle (about 45 degrees) to the long-term extension direction north of the fault. Similarly, block rotation in the northeastern Mojave Desert, while important, cannot be the primary explanation for left slip on the western and central Garlock fault, because the east-west striking, left-lateral faults that accommodate clockwise rotation in the northeastern Mojave Desert are only capable of explaining left-slip on the easternmost one-third or less of the Garlock fault. Some other mechanism is necessary to explain the relatively high slip rate that we have measured on the western Garlock fault and to explain the large bedrock offsets that extend westward beyond the region of block rotation. The conjugate model for the Garlock fault seems to be the only model capable of explaining the moderately high slip rate reported here for the western Garlock fault. It may also provide a useful view point for investigating why the rates of left-lateral strain accumulation along the Garlock fault (measured geodetically) are significantly lower than the rates of left-lateral Holocene strain release along the fault. If the Garlock fault is a conjugate fault within the broader, northwest-trending system of right-lateral shear, should one expect to ever see left-lateral elastic strain accumulation along it, or might left-lateral strain release along the fault be driven by the stresses caused by northwest-trending, right-lateral strain accumulation (as has been previously suggested by Savage and others, 2001)?

McGill, S. F.

2008-12-01

388

Seismic images and fault relations of the Santa Monica thrust fault, West Los Angeles, California  

USGS Publications Warehouse

In May 1997, the US Geological Survey (USGS) and the University of Southern California (USC) acquired high-resolution seismic reflection and refraction images on the grounds of the Wadsworth Veterans Administration Hospital (WVAH) in the city of Los Angeles (Fig. 1a,b). The objective of the seismic survey was to better understand the near-surface geometry and faulting characteristics of the Santa Monica fault zone. In this report, we present seismic images, an interpretation of those images, and a comparison of our results with results from studies by Dolan and Pratt (1997), Pratt et al. (1998) and Gibbs et al. (2000). The Santa Monica fault is one of the several northeast-southwest-trending, north-dipping, reverse faults that extend through the Los Angeles metropolitan area (Fig. 1a). Through much of area, the Santa Monica fault trends subparallel to the Hollywood fault, but the two faults apparently join into a single fault zone to the southwest and to the northeast (Dolan et al., 1995). The Santa Monica and Hollywood faults may be part of a larger fault system that extends from the Pacific Ocean to the Transverse Ranges. Crook et al. (1983) refer to this fault system as the Malibu Coast-Santa Monica-Raymond-Cucamonga fault system. They suggest that these faults have not formed a contiguous zone since the Pleistocene and conclude that each of the faults should be treated as a separate fault with respect to seismic hazards. However, Dolan et al. (1995) suggest that the Hollywood and Santa Monica faults are capable of generating Mw 6.8 and Mw 7.0 earthquakes, respectively. Thus, regardless of whether the overall fault system is connected and capable of rupturing in one event, individually, each of the faults present a sizable earthquake hazard to the Los Angeles metropolitan area. If, however, these faults are connected, and they were to rupture along a continuous fault rupture, the resulting hazard would be even greater. Although the Santa Monica fault represents a hazard to millions of people, its lateral extent and rupture history are not well known, due largely to limited knowledge of the fault location, geometry, and relationship to other faults. The Santa Monica fault has been obscured at the surface by alluvium and urbanization. For example, Dolan et al. (1995) could find only one 200-m-long stretch of the Santa Monica fault that was not covered by either streets or buildings. Of the 19-km length onshore section of the Santa Monica fault, its apparent location has been delineated largely on the basis of geomorphic features and oil-well drilling. Seismic imaging efforts, in combination with other investigative methods, may be the best approach in locating and understanding the Santa Monica fault in the Los Angeles region. This investigation and another recent seismic imaging investigation (Pratt et al., 1998) were undertaken to resolve the near-surface location, fault geometry, and faulting relations associated with the Santa Monica fault.

Catchings, R. D.; Gandhok, G.; Goldman, M. R.; Okaya, D.

2001-01-01

389

Fault Management Techniques in Human Spaceflight Operations  

NASA Technical Reports Server (NTRS)

This paper discusses human spaceflight fault management operations. Fault detection and response capabilities available in current US human spaceflight programs Space Shuttle and International Space Station are described while emphasizing system design impacts on operational techniques and constraints. Preflight and inflight processes along with products used to anticipate, mitigate and respond to failures are introduced. Examples of operational products used to support failure responses are presented. Possible improvements in the state of the art, as well as prioritization and success criteria for their implementation are proposed. This paper describes how the architecture of a command and control system impacts operations in areas such as the required fault response times, automated vs. manual fault responses, use of workarounds, etc. The architecture includes the use of redundancy at the system and software function level, software capabilities, use of intelligent or autonomous systems, number and severity of software defects, etc. This in turn drives which Caution and Warning (C&W) events should be annunciated, C&W event classification, operator display designs, crew training, flight control team training, and procedure development. Other factors impacting operations are the complexity of a system, skills needed to understand and operate a system, and the use of commonality vs. optimized solutions for software and responses. Fault detection, annunciation, safing responses, and recovery capabilities are explored using real examples to uncover underlying philosophies and constraints. These factors directly impact operations in that the crew and flight control team need to understand what happened, why it happened, what the system is doing, and what, if any, corrective actions they need to perform. If a fault results in multiple C&W events, or if several faults occur simultaneously, the root cause(s) of the fault(s), as well as their vehicle-wide impacts, must be determined in order to maintain situational awareness. This allows both automated and manual recovery operations to focus on the real cause of the fault(s). An appropriate balance must be struck between correcting the root cause failure and addressing the impacts of that fault on other vehicle components. Lastly, this paper presents a strategy for using lessons learned to improve the software, displays, and procedures in addition to determining what is a candidate for automation. Enabling technologies and techniques are identified to promote system evolution from one that requires manual fault responses to one that uses automation and autonomy where they are most effective. These considerations include the value in correcting software defects in a timely manner, automation of repetitive tasks, making time critical responses autonomous, etc. The paper recommends the appropriate use of intelligent systems to determine the root causes of faults and correctly identify separate unrelated faults.

O'Hagan, Brian; Crocker, Alan

2006-01-01

390

Fault slip during a glacial cycle  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

391

Effects of Fault Displacement on Emplacement Drifts  

SciTech Connect

The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

F. Duan

2000-04-25

392

The effects of fault orientation and fluid infiltration on fault rock assemblages at seismogenic depths  

NASA Astrophysics Data System (ADS)

The factors controlling the development of different types of fault rock assemblages and, more specifically, the formation of friction melts are still not fully understood. In this study we compared two exhumed strike-slip faults in the Adamello batholith (Southern Alps): the Gole Larghe and the Passo Cercen fault zones, active at 9-11 km depth and temperatures of 250-300 °C. Each fault zone consists of hundreds of sub-parallel strands exploiting pre-existing joints. The Gole Larghe fault strikes N105 ± 5° and is dextral; the fault rocks are cataclasites and widespread, centimetre-thick pseudotachylytes. The Passo Cercen fault strikes on average N130° and is formed by multiple fault horizons: fault segments striking N105°-N130° are mainly dextral, whereas faults striking N135°-N140° are mainly sinistral. Microstructural, mineralogical and geochemical investigations show that the fault rocks are cataclasites associated with thick epidote + K-feldspar + quartz veins and rare, millimetre-thick pseudotachylytes. Field evidence suggests that in both fault zones, the direction of the maximum horizontal stress ?1 was N135°. The Gole Larghe fault strikes at about 30° to ?1 and is favourably oriented for reactivation. By contrast, the Passo Cercen fault strikes at low angles to ?1 and is unfavourably oriented for reactivation, therefore requiring the development of high pore pressures, as suggested by the occurrence of extensive epidote veining and hydraulic breccias. It is proposed that frictional melting in the Passo Cercen fault zone was inhibited by the development of high pore pressures and low effective normal stresses.

Mittempergher, Silvia; Pennacchioni, Giorgio; Di Toro, Giulio

2009-12-01

393

Paleoseismicity of two historically quiescent faults in Australia: Implications for fault behavior in stable continental regions  

USGS Publications Warehouse

Paleoseismic studies of two historically aseismic Quaternary faults in Australia confirm that cratonic faults in stable continental regions (SCR) typically have a long-term behavior characterized by episodes of activity separated by quiescent intervals of at least 10,000 and commonly 100,000 years or more. Studies of the approximately 30-km-long Roopena fault in South Australia and the approximately 30-km-long Hyden fault in Western Australia document multiple Quaternary surface-faulting events that are unevenly spaced in time. The episodic clustering of events on cratonic SCR faults may be related to temporal fluctuations of fault-zone fluid pore pressures in a volume of strained crust. The long-term slip rate on cratonic SCR faults is extremely low, so the geomorphic expression of many cratonic SCR faults is subtle, and scarps may be difficult to detect because they are poorly preserved. Both the Roopena and Hyden faults are in areas of limited or no significant seismicity; these and other faults that we have studied indicate that many potentially hazardous SCR faults cannot be recognized solely on the basis of instrumental data or historical earthquakes. Although cratonic SCR faults may appear to be nonhazardous because they have been historically aseismic, those that are favorably oriented for movement in the current stress field can and have produced unexpected damaging earthquakes. Paleoseismic studies of modern and prehistoric SCR faulting events provide the basis for understanding of the long-term behavior of these faults and ultimately contribute to better seismic-hazard assessments.

Crone, A. J.; De Martini, P. M.; Machette, M. M.; Okumura, K.; Prescott, J. R.

2003-01-01

394

Magnitude, geomorphologic response and climate links of lake level oscillations at Laguna Potrok Aike, Patagonian steppe (Argentina)  

NASA Astrophysics Data System (ADS)

Laguna Potrok Aike is a large maar lake located in the semiarid steppe of southern Patagonia known for its Lateglacial and Holocene lake level fluctuations. Based on sedimentary, seismic and geomorphological evidences, the lake level curve is updated and extended into the Last Glacial period and the geomorphological development of the lake basin and its catchment area is interpreted.Abrasion and lake level oscillations since at least ˜50 ka caused concentric erosion of the surrounding soft rocks of the Miocene Santa Cruz Formation and expanded the basin diameter by approximately 1 km. A high lake level and overflow conditions of the lake were dated by luminescence methods and tephra correlation to the early Lateglacial as well as to ˜45 ka. The lowest lake level of record occurred during the mid-Holocene. A further lake level drop was probably prevented by groundwater supply. This low lake level eroded a distinct terrace into lacustrine sediments. Collapse of these terraces probably caused mass movement deposits in the profundal zone of the lake. After the mid-Holocene lake level low stand a general and successive transgression occurred until the Little Ice Age maximum; i.e. ca 40 m above the local groundwater table. Frequent lake level oscillations caused deflation of emerged terraces only along the eastern shoreline due to prevailing westerly winds. Preservation of eolian deposits might be linked to relatively moist climate conditions during the past 2.5 ka.Precisely dated lake level reconstructions in the rain-shadow of the Andes document high Last Glacial and low Holocene lake levels that could suggest increased precipitation during the Last Glacial period. As permafrost in semiarid Patagonia is documented and dated to the Last Glacial period we argue that the frozen ground might have increased surficial runoff from the catchment and thus influenced the water balance of the lake. This is important for investigating the glacial to Holocene latitudinal shift and/or strengthening of the Southern Hemispheric Westerlies by using lake level reconstructions as a means to assess the regional water balance. Our interpretation explains the contradiction with investigations based on pollen data indicating drier climatic conditions for the Last Glacial period.

PASADO science Team Kliem, P.; Buylaert, J. P.; Hahn, A.; Mayr, C.; Murray, A. S.; Ohlendorf, C.; Veres, D.; Wastegård, S.; Zolitschka, B.

2013-07-01

395

Magnitude, geomorphologic response and climate links of lake level oscillations at Laguna Potrok Aike, Patagonian steppe (Argentina)  

NASA Astrophysics Data System (ADS)

Laguna Potrok Aike is a large maar lake located in the semiarid steppe of southern Patagonia known for its Lateglacial and Holocene lake level fluctuations. Based on sedimentary, seismic and geomorphological evidences, the lake level curve is updated and extended into the Last Glacial period and the geomorphological development of the lake basin and its catchment area is interpreted. Abrasion and lake level oscillations since at least ˜50 ka caused concentric erosion of the surrounding soft rocks of the Miocene Santa Cruz Formation and expanded the basin diameter by approximately 1 km. A high lake level and overflow conditions of the lake were dated by luminescence methods and tephra correlation to the early Lateglacial as well as to ˜45 ka. The lowest lake level of record occurred during the mid-Holocene. A further lake level drop was probably prevented by groundwater supply. This low lake level eroded a distinct terrace into lacustrine sediments. Collapse of these terraces probably caused mass movement deposits in the profundal zone of the lake. After the mid-Holocene lake level low stand a general and successive transgression occurred until the Little Ice Age maximum; i.e. ca 40 m above the local groundwater table. Frequent lake level oscillations caused deflation of emerged terraces only along the eastern shoreline due to prevailing westerly winds. Preservation of eolian deposits might be linked to relatively moist climate conditions during the past 2.5 ka. Precisely dated lake level reconstructions in the rain-shadow of the Andes document high Last Glacial and low Holocene lake levels that could suggest increased precipitation during the Last Glacial period. As permafrost in semiarid Patagonia is documented and dated to the Last Glacial period we argue that the frozen ground might have increased surficial runoff from the catchment and thus influenced the water balance of the lake. This is important for investigating the glacial to Holocene latitudinal shift and/or strengthening of the Southern Hemispheric Westerlies by using lake level reconstructions as a means to assess the regional water balance. Our interpretation explains the contradiction with investigations based on pollen data indicating drier climatic conditions for the Last Glacial period.

Kliem, P.; Buylaert, J. P.; Hahn, A.; Mayr, C.; Murray, A. S.; Ohlendorf, C.; Veres, D.; Wastegård, S.; Zolitschka, B.; The Pasado Science Team

396

Rainfall-runoff modeling of recent hydroclimatic change in a subtropical lake catchment: Laguna Mar Chiquita, Argentina  

NASA Astrophysics Data System (ADS)

SummaryThe 1970s abrupt lake level rise of Laguna Mar Chiquita in central Argentina was shown to be driven by an increase in the Rio Sali-Dulce discharge outflowing from the northern part of the lake catchment. This regional hydrological change was consistent with the 20th century hydroclimatic trends observed in southeastern South America. However, little is known about the impacts of climate or land cover changes on this regional hydrological change causing the sharp lake level rise. To address this question, the present study aims to provide an integrated basin-lake model. We used the physically-based SWAT model in order to simulate streamflow in the Sali-Dulce Basin. The ability of SWAT to simulate non-stationary hydrological conditions was evaluated by a cross-calibration exercise. Based on observed daily meteorological data over 1973-2004, two successive 9-year periods referred to as wet (P1976-1985 = 1205 mm/yr) and dry (P1986-1995 = 796 mm/yr) periods were selected. The calibration yielded similar Nash-Sutcliffe efficiencies (NSE) at the monthly time scale for both periods (NSEwet = 0.86; NSEdry = 0.90) supporting the model's ability to adapt its structure to changing climatic situations. The simulation was extended in scarce data conditions over 1931-1972 and the simulation of monthly discharge values was acceptable (NSE = 0.71). When precipitation in the model was increased until it reach the change observed in the 1970s (?P/P¯=22%), the resulting increase in streamflow was found to closely match the 1970s hydrological change (?Q/Q¯=45%). Sensitivity analyses revealed that the land cover changes had a minor impact on the 1970s hydrological changes in the Sali-Dulce Basin. Integrating the SWAT simulations within the lake model over 1973-2004 provided lake level variations similar to those obtained using observed discharge values. Over the longer period, going back to 1931, the main features of lake levels were still adequately reproduced, which suggests that this basin-lake model is a promising approach for simulating long-term lake level fluctuations in response to climate.

Troin, Magali; Vallet-Coulomb, Christine; Piovano, Eduardo; Sylvestre, Florence

2012-12-01

397

Intermittent/transient fault phenomena in digital systems  

NASA Technical Reports Server (NTRS)

An overview of the intermittent/transient (IT) fault study is presented. An interval survivability evaluation of digital systems for IT faults is discussed along with a method for detecting and diagnosing IT faults in digital systems.

Masson, G. M.

1977-01-01

398

A fault-tolerant RISC microprocessor for spacecraft applications  

NASA Technical Reports Server (NTRS)

Viewgraphs on a fault-tolerant RISC microprocessor for spacecraft applications are presented. Topics covered include: reduced instruction set computer; fault tolerant registers; fault tolerant ALU; and double rail CMOS logic.

Timoc, Constantin; Benz, Harry

1990-01-01

399

Fault Tolerant Homopolar Magnetic Bearings  

NASA Technical Reports Server (NTRS)

Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

2003-01-01

400

Fault-tolerant software - Experiment with the sift operating system. [Software Implemented Fault Tolerance computer  

NASA Technical Reports Server (NTRS)

Results are presented of an experiment conducted in the NASA Avionics Integrated Research Laboratory (AIRLAB) to investigate the implementation of fault-tolerant software techniques on fault-tolerant computer architectures, in particular the Software Implemented Fault Tolerance (SIFT) computer. The N-version programming and recovery block techniques were implemented on a portion of the SIFT operating system. The results indicate that, to effectively implement fault-tolerant software design techniques, system requirements will be impacted and suggest that retrofitting fault-tolerant software on existing designs will be inefficient and may require system modification.

Brunelle, J. E.; Eckhardt, D. E., Jr.

1985-01-01

401

Implementation of a model based fault detection and diagnosis technique for actuation faults of the SSME  

NASA Astrophysics Data System (ADS)

In a previous study, Guo, Merrill and Duyar, 1990, reported a conceptual development of a fault detection and diagnosis system for actuation faults of the Space Shuttle main engine. This study, which is a continuation of the previous work, implements the developed fault detection and diagnosis scheme for the real time actuation fault diagnosis of the Space Shuttle Main Engine. The scheme will be used as an integral part of an intelligent control system demonstration experiment at NASA Lewis. The diagnosis system utilizes a model based method with real time identification and hypothesis testing for actuation, sensor, and performance degradation faults.

Duyar, A.; Guo, T.-H.; Merrill, W.; Musgrave, J.

402

Implementation of a model based fault detection and diagnosis technique for actuation faults of the SSME  

NASA Technical Reports Server (NTRS)

In a previous study, Guo, Merrill and Duyar, 1990, reported a conceptual development of a fault detection and diagnosis system for actuation faults of the Space Shuttle main engine. This study, which is a continuation of the previous work, implements the developed fault detection and diagnosis scheme for the real time actuation fault diagnosis of the Space Shuttle Main Engine. The scheme will be used as an integral part of an intelligent control system demonstration experiment at NASA Lewis. The diagnosis system utilizes a model based method with real time identification and hypothesis testing for actuation, sensor, and performance degradation faults.

Duyar, A.; Guo, T.-H.; Merrill, W.; Musgrave, J.

1991-01-01

403

Intermittent/transient faults in digital systems  

NASA Technical Reports Server (NTRS)

Containment set techniques are applied to 8085 microprocessor controllers so as to transform a typical control system into a slightly modified version, shown to be crashproof: after the departure of the intermittent/transient fault, return to one proper control algorithm is assured, assuming no permanent faults occur.

Masson, G. M.; Glazer, R. E.

1982-01-01

404

Seismic faults in the Aegean area  

NASA Astrophysics Data System (ADS)

Reliable fault plane solutions of shallow earthquakes and information on surface fault traces in combination with other seismic, geomorphological and geological information have been used to determine the orientation and other properties of the seismic faults in the Aegean and surrounding area. Thrust faults having an about NW-SE strike occur in the outer seismic zone along western Albania-westernmost part of mainland of Greece-Ionian Sea-south of Crete-south of Rhodes. The inner part of the area is dominated by strike-slip and normal faulting. Strike-slip with an about NE-SW slip direction occurs in the inner part of the Hellenic arc along the line Peloponnesus-Cyclades-Dodecanese-southwest Turkey as well as along a zone which is associated with the northern Aegean trough and the northwesternmost part of Anatolia. All other regions in the inner part of the area are characterized by normal faulting. The slip direction of the normal faults has an about SW-NE direction in Crete (N38°E) and an about E-W direction (N81°E) in a zone which trends N-S in eastern Albania and its extension to western mainland of Greece. In all other regions (central Greece-southern Yugoslavia and Bulgaria, western Turkey) the slip of the normal faults has an about N-S direction.

Papazachos, B. C.; Kiratzi, A. A.; Hatzidimitriou, P. M.; Rocca, A. C.

1984-06-01

405

Fault Injection in VHDL Descriptions and Emulation  

Microsoft Academic Search

Analyzing at an early stage of the design the potential faulty behaviors of a circuit becomes a major concern due to the increasing probability of faults. It is proposed to carry out such an analysis using fault injections in RT-level VHDL descriptions and hardware prototyping of the circuit under design. Injection of erroneous transitions is automated and results are presented

Régis Leveugle

2000-01-01

406

Friction, overpressure and fault normal compression  

SciTech Connect

More than twenty-five years ago Miller and Low reported the existence of a threshold pore pressure gradient below which water would not flow through clay. Recent experimental observations of the shear strength of structured water on biotite surfaces have provided a physical basis for understanding this threshold gradient. The existence of this phenomenon has profound implications for the rheological properties of mature fault zones, such as the San Andreas, that contain large thickness of fault gouge. For example, a clay-filled fault zone about 1 km wide at the base of the surface could support core fluid pressure equal to the maximum principal stress over the entire seismogenic zone. As a result, the fault would have near-zero strength and the maximum principal stress measured on the flanks of the fault, would be oriented normal to the fault surface. Another consequence of the threshold gradient is that normal hydrostatic fluid pressures outside the fault zone could coexist with near-lithostatic fluid pressures in the interior of the fault zone without the need for continual replenishment of the overpressured fluid. In addition, the pore pressure at any point should never exceed the local minimum principal stress so that hydrofracture will not occur.

Byerlee, J. (Geological Survey, Menlo Park, CA (USA))

1990-11-01

407

Philippine fault: A key for Philippine kinematics  

Microsoft Academic Search

On the basis of new geologic data and a kinematic analysis, we establish a simple kinematic model in which the motion between the Philippine Sea plate and Eurasia is distributed on two boundaries: the Philippine Trench and the Philippine fault. This model predicts a velocity of 2 to 2.5 cm\\/yr along the fault. Geologic data from the Visayas provide an

E. Barrier; P. Huchon; M. Aurelio

1991-01-01

408

Diagnosis of Ambiguous Faults in Simple Networks  

Microsoft Academic Search

We propose a theory of how individuals diagnose faults, and we report two experiments that tested its application to the diagnosis of faults in simple Boolean systems. Participants were presented with simple network diagrams in which a signal was transmitted from a set of input nodes to an output node, via a set of connecting nodes. Their task was to

Geoffrey P. Goodwin

409

Thermal decomposition along natural faults during earthquakes  

NASA Astrophysics Data System (ADS)

Earthquake slip is facilitated by a number of thermally activated physicochemical processes that are triggered by temperature rise during fast fault motion, i.e. frictional heating. Most of our knowledge on these processes is derived from theoretical and experimental studies. However additional information can be provided by direct observation of ancient faults exposed at the Earth's surface. Although fault rock indicators of earthquake processes along ancient faults have been inferred, the only unambiguous and rare evidence of seismic sliding from natural faults is due to solidified friction melts or pseudotachylytes. Here we document a gamut of natural fault rocks produced by thermally activated processes during earthquake slip. These processes occurred at 2-3 km of depth, along a thin (0.3-1.0 mm) principal slip zone of a regional thrust fault that accommodated several kilometers of displacement. In the slip zone, composed of ultra fine-grained fault rocks made of calcite and minor clays, we observe the presence of relict calcite and clay, numerous vesicles, poorly crystalline/amorphous phases and newly formed calcite skeletal crystals. These observations indicate that during earthquake rupture, frictional heating induced calcite decarbonation and phyllosilicate dehydration producing a viscous, fluid-rich, layer able to lubricate the slip zone and facilitate earthquake slip.

Collettini, Cristiano; Viti, Cecilia; Tesei, Telemaco; Mollo, Silvio

2013-04-01

410

Detecting Latent Faults In Digital Flight Controls  

NASA Technical Reports Server (NTRS)

Report discusses theory, conduct, and results of tests involving deliberate injection of low-level faults into digital flight-control system. Part of study of effectiveness of techniques for detection of and recovery from faults, based on statistical assessment of inputs and outputs of parts of control systems. Offers exceptional new capability to establish reliabilities of critical digital electronic systems in aircraft.

Mcgough, John; Mulcare, Dennis; Larsen, William E.

1992-01-01

411

Land Seismic Profiling of the Tacoma Fault  

Microsoft Academic Search

Abstract This report summarizes,the results from seismic reflection profiling across the Tacoma fault zone (TFZ) during the summer,2005 field season. I collected three seismic transects to locate and characterize faults associated with the TFZ. Each transect crosses the northern portions of the Tacoma Basin and the projected location ofthe main strand of the TFZ. Additionally, I acquired one profile across

Lee M. Liberty

412

Holocene fault scarps near Tacoma, Washington, USA  

Microsoft Academic Search

Airborne laser mapping confirms that Holocene active faults traverse the Puget Sound metropolitan area, northwestern continental United States. The mapping, which detects forest-floor relief of as little as 15 cm, reveals scarps along geophysical lineaments that separate areas of Holocene uplift and subsidence. Along one such line of scarps, we found that a fault warped the ground surface between A.D.

Brian L. Sherrod; Thomas M. Brocher; Craig S. Weaver; Robert C. Bucknam; Richard J. Blakely; Harvey M. Kelsey; Alan R. Nelson; Ralph Haugerud

2004-01-01

413

Tectonics and Landforms: Types of Faults  

NSDL National Science Digital Library

This resource offers animations depicting the defining motions of five different types of faults. Also included is a data visualization showing the geographic patterns of faults and earthquakes, and a documentary video which discusses a series of great earthquakes that occurred between 1811 - 1812 and includes an animation of how the Mississippi River Valley was created.

Ritter, Michael

414

SDRAM Delay Fault Modeling and Performance Testing  

Microsoft Academic Search

DRAM timing parameter testing has always been considered a time-consuming process. This paper presents a systematic approach to analysis and classification of the synchronous DRAM (SDRAM) delay failure modes. Four delay fault models with March expression are proposed to cover important DRAM timing parameters. By at-speed March testing of these four types of delay faults, the authors can verify the

Yu-tsao Hsing; Chun-chieh Huang; Jen-chieh Yeh; Cheng-wen Wu

2007-01-01

415

A Game Theoretic Fault Detection Filter  

NASA Technical Reports Server (NTRS)

The fault detection process is modelled as a disturbance attenuation problem. The solution to this problem is found via differential game theory, leading to an H(sub infinity) filter which bounds the transmission of all exogenous signals save the fault to be detected. For a general class of linear systems which includes some time-varying systems, it is shown that this transmission bound can be taken to zero by simultaneously bringing the sensor noise weighting to zero. Thus, in the limit, a complete transmission block can he achieved, making the game filter into a fault detection filter. When we specialize this result to time-invariant system, it is found that the detection filter attained in the limit is identical to the well known Beard-Jones Fault Detection Filter. That is, all fault inputs other than the one to be detected (the "nuisance faults") are restricted to an invariant subspace which is unobservable to a projection on the output. For time-invariant systems, it is also shown that in the limit, the order of the state-space and the game filter can be reduced by factoring out the invariant subspace. The result is a lower dimensional filter which can observe only the fault to be detected. A reduced-order filter can also he generated for time-varying systems, though the computational overhead may be intensive. An example given at the end of the paper demonstrates the effectiveness of the filter as a tool for fault detection and identification.

Chung, Walter H.; Speyer, Jason L.

1995-01-01

416

Diagnostic expert systems from dynamic fault trees  

Microsoft Academic Search

A methodology for developing a diagnostic map for systems that can be analyzed via a dynamic fault tree is proposed in this paper. This paper shows how to automatically design a diagnostic decision tree from a dynamic fault tree used for reliability analysis. In particular the methodology makes use of Markov chains since they are mathematical models used for reliability

Tariq Assaf; Joanne Bechta Dugan

2004-01-01

417