Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

PubMed Central

Baresel, Björn; Bucher, Hugo; Bagherpour, Borhan; Brosse, Morgane; Guodun, Kuang; Schaltegger, Urs

2017-01-01

New high-resolution U-Pb dates indicate a duration of 89 ± 38 kyr for the Permian hiatus and of 14 ± 57 kyr for the overlying Triassic microbial limestone in shallow water settings of the Nanpanjiang Basin, South China. The age and duration of the hiatus coincides with the Permian-Triassic boundary (PTB) and the extinction interval in the Meishan Global Stratotype Section and Point, and strongly supports a glacio-eustatic regression, which best explains the genesis of the worldwide hiatus straddling the PTB in shallow water records. In adjacent deep marine troughs, rates of sediment accumulation display a six-fold decrease across the PTB compatible with a dryer and cooler climate as indicated by terrestrial plants. Our model of the Permian-Triassic boundary mass extinction (PTBME) hinges on the synchronicity of the hiatus with the onset of the Siberian Traps volcanism. This early eruptive phase released sulfur-rich volatiles into the stratosphere, thus simultaneously eliciting a short-lived ice age responsible for the global regression and a brief but intense acidification. Abrupt cooling, shrunk habitats on shelves and acidification may all have synergistically triggered the PTBME. Subsequently, the build-up of volcanic CO2 induced a transient cool climate whose early phase saw the deposition of the microbial limestone. PMID:28262815

Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

NASA Astrophysics Data System (ADS)

Baresel, Björn; Bucher, Hugo; Bagherpour, Borhan; Brosse, Morgane; Guodun, Kuang; Schaltegger, Urs

2017-03-01

New high-resolution U-Pb dates indicate a duration of 89 ± 38 kyr for the Permian hiatus and of 14 ± 57 kyr for the overlying Triassic microbial limestone in shallow water settings of the Nanpanjiang Basin, South China. The age and duration of the hiatus coincides with the Permian-Triassic boundary (PTB) and the extinction interval in the Meishan Global Stratotype Section and Point, and strongly supports a glacio-eustatic regression, which best explains the genesis of the worldwide hiatus straddling the PTB in shallow water records. In adjacent deep marine troughs, rates of sediment accumulation display a six-fold decrease across the PTB compatible with a dryer and cooler climate as indicated by terrestrial plants. Our model of the Permian-Triassic boundary mass extinction (PTBME) hinges on the synchronicity of the hiatus with the onset of the Siberian Traps volcanism. This early eruptive phase released sulfur-rich volatiles into the stratosphere, thus simultaneously eliciting a short-lived ice age responsible for the global regression and a brief but intense acidification. Abrupt cooling, shrunk habitats on shelves and acidification may all have synergistically triggered the PTBME. Subsequently, the build-up of volcanic CO2 induced a transient cool climate whose early phase saw the deposition of the microbial limestone.

On the age of the Jurassic-Cretaceous boundary

NASA Astrophysics Data System (ADS)

Lena, Luis; Ramos, Victor; Pimentel, Marcio; Aguirre-Urreta, Beatriz; Naipauer, Maximiliano; Schaltegger, Urs

2017-04-01

Calibrating the geologic time is of utmost importance to understanding geological and biological processes throughout Earth history. The Jurassic-Cretaceous boundary has proven to be one of the most problematic boundaries to calibrate in the geologic time. The present definition of the Jurassic-Cretaceous boundary still remains contentious mainly because of the dominant endemic nature of the flora and fauna in stratigraphic sections, which hinders an agreement on a GSSP. Consequently, an absolute and precise age for the boundary is yet to meet an agreement among the community. Additionally, integrating chemical, paleomagnetic or astronomical proxies to aid the definition of the boundary has also proven to be difficult because the boundary lacks any abrupt geochemical changes or recognizable geological events. However, the traditional Berriasella jacobi Subzone is disregarded as a primary marker and the use of calpionellids has been gaining momentum for defining the boundary. The Jurassic Cretaceous boundary in the Vaca Muerta Fm. in the Nuequen Basin of the Andes is a potential candidate for the boundary stratotype because of its high density of ammonites, nannofossils and interbedded datable horizons. Consequently, the Jurassic-Cretaceous boundary is very well defined in the Vaca Muerta Fm. On the basis of both ammonites and nannofossils. Here we present new high-precision U-Pb age determinations from two volcanic ash beds that bracket the age of the Jurassic-Cretaceous boundary: 1) ash bed LLT_14_9, with a 206Pb/238U age of 139.7 Ma, which is 2 meters above Jurassic-Cretaceous boundary based on the Argetiniceras noduliferum (Early Berriasian ) and Substeueroceras Koeneni (Late Tithonian) ammonites zone; and 2) bed LLT_14_10, with an age of 140.1 Ma, located 3m below the J-K boundary based on last occurrence of the nannofossils N. kamptneri minor and N. steinmanni minor. Therefore, we propose that the age of the Jurassic-Cretaceous boundary should be close to 140 Ma, which is in conflict with the currently set age of 145 Ma. Therefore, this suggests a revision of the age of the Jurassic-Cretaceous boundary.

Timing is everything - implications of a new correlation of Triassic-Jurassic boundary successions and the Central Atlantic Magmatic Province

NASA Astrophysics Data System (ADS)

Lindström, Sofie; van de Schootbrugge, Bas; Pedersen, Gunver K.; Alsen, Peter; Thibault, Nicolas; Hansen, Katrine H.; Dybkjær, Karen; Bjerrum, Christian J.; Nielsen, Lars Henrik

2017-04-01

Understanding mass extinctions requires a clear insight into the stratigraphy of boundary sections, which allows for long-distance correlations and correct distinction of the sequence of events. However, even after the ratification of a Global Stratotype Section and Point, global correlations of Triassic-Jurassic boundary (TJB) successions are hampered by the fact that many of the traditionally used fossil groups were severely affected by the end-Triassic mass extinction (ETE). Recently, a new correlation of key TJB successions in Europe, U.S.A. and Peru, based on a combination of biotic (palynology and ammonites), geochemical (δ13Corg) and radiometric (U/Pb ages) constraints, was presented. This new correlation has an impact on the causality and temporal development during the end-Triassic event, as it indicates that the bulk of the hitherto dated, high-titanium, quartz normalized volcanism of the Central Atlantic Magmatic Province (CAMP) preceded or was contemporaneous to the onset of the mass extinction. It further shows that the maximum phase of the mass extinction, which affected both the terrestrial and marine ecosystems, was associated with a major regression and repeated, enhanced earthquake activity in Europe. A subsequent transgression resulted in the formation of hiati or condensed successions in many areas in Europe. Later phases of volcanic activity of the CAMP, producing low titanium, quartz normalized and high-iron, quartz normalized basaltic rocks, continued close to the first occurrence of Jurassic ammonites and the defined TJB. This new correlations enables a reconstruction of the sequence of events; including records of e.g. pCO2 from soil carbonates and plant fossils, rare earth elements, biomarkers, charcoal, which allows an insight into the causality of this biotic crises.

The base of the Campanian: a magnetostratigraphic definition, integrated biostratigraphy and isotope stratigraphy

NASA Astrophysics Data System (ADS)

Wagreich, Michael; Dinarès-Turell, Jaume; Wolfgring, Erik; Omer Yilmaz, Ismail

2017-04-01

The base of the Campanian, the longest stage of the Late Cretaceous, is still not defined by a GSSP (Global Boundary Stratotype Section and Point). Furthermore, no consensus exists about the boundary criterion: macrofossils like ammonites and inoceramids suffer from bioprovincialism. The LAD of the crinoid Marsupites testudinarius was proposed as the primary fossil marker. But this marker is mainly a chalk facies fossil, which is rare to absent in pelagic low-latitudes, absent in oceanic sections, and the LAD may be influenced by palaeoenvironmental and palaecological settings. More recently, a boundary defined by magnetostratigraphy, i.e. the base of Chron C33r after the Long Cretaceous Normal Chron C34n, has been discussed. Western Tethyan pelagic sections from Austria and Turkey provide means for integrating various stratigraphic methods. A robust magnetostratigraphic signal was found at the Postalm section (Gosau Group, Northern Calcareous Alps, Austria) which may serve as a reference section for the northwestern Tethys. Including nearby complementary sections, palaeomagnetic data can be integrated with strontium isotope stratigraphy and stable isotope data, planktonic foraminifera and calcareous nannoplankton biostratigraphy, , and ammonite, crinoid and inoceramid data. The Postalm section shows a deepening trend from upper Santonian conglomerates and grey shelf marls to pelagic bathyal red marly limestones of Campanian age. Palaeomagnetic data allow identifying the top of Chron C34n and the following reversal in the lower part of the red marly limestones. A 1 m-thick interval of high magnetic susceptibility is present at the end of C34n. Two of the main suggested biomarkers to pinpoint the Santonian-Campanian boundary, i.e. the last occurrence of the planktonic foraminifer Dicarinella asymetrica and the first occurrence of the nannofossil Broinsonia parca parca, occur in close proximity to the reversal, which is suggested herein as the primary marker event for the base of the Campanian. Strontium isotope stratigraphy indicates a value of 0.707534. Both carbon and oxygen isotope values show a negative excursion just below the boundary. The positive Santonian-Campanian boundary carbon isotope event (SCBE) starts probably just at the boundary level. This interval is considered to correspond to a short sea-level high in the late Santonian followed by a lowstand at the Santonian-Campanian boundary. Macrofossil data from the nearby Schattau section indicate the late Santonian Paraplanum ammonite Subzone, the presence of the crinoid Marsupites laevigatus and inoceramids, e.g. Cordiceramus muelleri muelleri, below the boundary as defined by magnetostratigraphy. Sections from the western Tethyan Mudurnu-Göynük basin (NW Turkey) provide similar evidence for the Santonian-Campanian boundary interval. Near Göynük town, a reversal of the magnetic polarity was identified to represent the base of C33r within a pelagic section. Biostratigraphic data suggest an age from the late Santonian Dicarinella asymetrica to the early Campanian Globotruncanita elevata planktonic foraminifera zone, and nannofossil zones UC13-CC14. Results from the assessment of field magnetic susceptibility give evidence for Milankovitch cycles, presumably the 405 ka eccentricity cycle.

Sedimentary organic matter characterization of the Triassic-Jurassic boundary GSSP at Kuhjoch (Austria)

NASA Astrophysics Data System (ADS)

Ruhl, M.; Veld, H.; Kürschner, W. M.

2010-03-01

The Triassic-Jurassic (T-J) boundary interval coincides with enhanced extinction rates in the marine realm and pronounced changes in terrestrial ecosystems on the continents. It is further marked by distinct negative excursions in the δ13C org and δ13C carb signature that may represent strong perturbations of the global carbon cycle. We present integrated geochemical, stable-isotope and palynological data from the Kuhjoch section, the Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic (Northern Calcareous Alps, Austria). We show that the initial carbon isotope excursion (CIE), coinciding with the marine extinction interval and the formation of black shales in the western Tethys Eiberg Basin, is marked by only minor changes in kerogen type, which is mainly of terrestrial origin. Increased Total Organic Carbon (TOC) concentrations of 9% at the first half of the initial CIE coincide with Hydrogen Index (HI) values of over 600 mg HC/g TOC. The high correlation (with R2 = 0.93) between HI values and terrestrial Cheirolepidiaceaen conifer pollen suggests a terrestrial source for the hydrogen enriched organic compounds. The lack of major changes in source of the sedimentary organic matter suggests that changes in the δ13C org composition are genuine and represent true disturbances of the global C-cycle. The sudden decrease in total inorganic carbon (TIC) concentrations likely represents the onset of a biocalcification crisis. It coincides with a 4.5‰ negative shift in δ13C org values and possibly corresponds to the onset of CAMP related volcanic activity. The second half of the initial CIE is marked by the dramatic increase of green algae remains in the sediment. The simultaneous increase of the C org/N tot ratio suggests increased marine primary production at the final stage of black shale formation.

Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

NASA Astrophysics Data System (ADS)

Baresel, Bjoern; Bucher, Hugo; Bagherpour, Borhan; Brosse, Morgane; Guodun, Kuang; Schaltegger, Urs

2017-04-01

High-precision U-Pb dating of single-zircon crystals by chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) is applied to volcanic beds that are intercalated in sedimentary sequences across the Permian-Triassic boundary (PTB). By assuming that the zircon crystallization age closely approximate that of the volcanic eruption and subsequent deposition, U-Pb zircon geochronology is the preferred approach for dating abiotic and biotic events, such as the formational PTB and the Permian-Triassic boundary mass extinction (PTBME). We will present new U-Pb zircon dates for a series of volcanic ash beds in shallow-marine Permian-Triassic sections in the Nanpanjiang Basin, South China. These high-resolution U-Pb dates indicate a duration of 90 ± 38 kyr for the Permian sedimentary hiatus and a duration of 13 ± 57 kyr for the overlying Triassic microbial limestone in the shallow water settings of the Nanpanjiang pull apart Basin. The age and duration of the hiatus coincides with the formational PTB and the extinction interval in the Meishan Global Stratotype Section and Point, thus strongly supporting a glacio-eustatic regression, which best explains the genesis of the worldwide hiatus straddling the PTB in shallow water records. In adjacent deep marine troughs, rates of sediment accumulation display a six-fold decrease across the PTB compatible with a dryer and cooler climate during the Griesbachian as indicated by terrestrial plants. Our model of the PTBME hinges on the synchronicity of the hiatus with the onset of the Siberian Traps volcanism. This early eruptive phase likely released sulfur-rich volatiles into the stratosphere, thus simultaneously eliciting a short-lived ice age responsible for the global regression and a brief but intense acidification. Abrupt cooling, shrunk habitats on shelves and acidification may all have synergistically triggered the PTBME. Subsequently, the build-up of volcanic CO2 induced this transient cool climate whose early phase saw the deposition of the microbial limestone.

Intercalibration of radioisotopic and astrochronologic time scales for the Cenomanian-Turonian boundary interval, western interior Basin, USA

USGS Publications Warehouse

Meyers, S.R.; Siewert, S.E.; Singer, B.S.; Sageman, B.B.; Condon, D.J.; Obradovich, J.D.; Jicha, B.R.; Sawyer, D.A.

2012-01-01

We develop an intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian-Turonian boundary (CTB) interval near the Global Stratotype Section and Point in Colorado, USA, where orbitally influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for 40Ar/ 39Ar and U-Pb dating. Paired 40Ar/ 39Ar and U-Pb ages are determined from four bentonites that span the Vascoceras diartianum to Pseudaspidoceras flexuosum ammonite biozones, utilizing both newly collected material and legacy sanidine samples of J. Obradovich. Comparison of the 40Ar/ 39Ar and U-Pb results underscores the strengths and limitations of each system, and supports an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. The radioisotopic data and published astrochronology are employed to develop a new CTB time scale, using two statistical approaches: (1) a simple integration that yields a CTB age of 93.89 ?? 0.14 Ma (2??; total radioisotopic uncertainty), and (2) a Bayesian intercalibration that explicitly accounts for orbital time scale uncertainty, and yields a CTB age of 93.90 ?? 0.15 Ma (95% credible interval; total radioisotopic and orbital time scale uncertainty). Both approaches firmly anchor the floating orbital time scale, and the Bayesian technique yields astronomically recalibrated radioisotopic ages for individual bentonites, with analytical uncertainties at the permil level of resolution, and total uncertainties below 2???. Using our new results, the duration between the Cenomanian-Turonian and the Cretaceous-Paleogene boundaries is 27.94 ?? 0.16 Ma, with an uncertainty of less than one-half of a long eccentricity cycle. ?? 2012 Geological Society of America.

Berriasian (Early Cretaceous) radiometric ages from the Grindstone Creek Section, Sacramento Valley, California

USGS Publications Warehouse

Bralower, T.J.; Ludwig, K. R.; Obradovich, J.D.

1990-01-01

The Grindstone Creek Section, Glenn County, Northern California is a sequence of hemipelagic mudstone, siltstone and sandstone interbedded with concretionary limestone and a few thin tuffs and bentonites. Two tuffs have been collected from a narrow interval of this sequence and subjected to mineralogical and isotopic analyses. UPb isotopic analyses of zircon fractions from these volcanic horizons indicate an age of 137.1 + 1.6/-0.6 Ma. A detailed investigation has been conducted on the calcareous nannofossil stratigraphy of this section based on numerous samples with moderately preserved assemblages. The nannoflora is largely of Tethyan affinity, and allows direct correlation with the Berriasian stratotype section, with sections with published magnetostratigraphies and with a DSDP site drilled between known magnetic anomalies. The dated tuffs lie in the lower part of the upper Berriasian Cretarhabdus angustiforatus Zone (Assipetra infracretacea Subzone) and within the narrow range of Rhagodiscus nebulosus. At three different sections, this subzone can be correlated with M-sequence Polarity Zones M16 and M16n. An independent magnetostratigraphic correlation is provided at DSDP Site 387, drilled between anomalies M15 and M16, where basal sediments contain R. nebulosus. Buchia collected within a meter of the lower tuff lie within the B. uncitoides Zone which is Berriasian in age. The upper tuff level, which occurs 65 m above the lower tuff, is situated within the overlying B. pacifica Zone. This zone had previously been correlated with the early Valanginian, but is clearly also partly of Berriasian age based on nannofossil stratigraphy. Our results allow an estimate of the age of the Berriasian-Valanginian and Jurassic-Cretaceous boundaries of 135.1 Ma and 141.1 Ma, respectively, and these fall within the range of, but differ significantiy from, several published time-scales. ?? 1990.

High-precision timeline for Earth’s most severe extinction

PubMed Central

Burgess, Seth D.; Bowring, Samuel; Shen, Shu-zhong

2014-01-01

The end-Permian mass extinction was the most severe loss of marine and terrestrial biota in the last 542 My. Understanding its cause and the controls on extinction/recovery dynamics depends on an accurate and precise age model. U-Pb zircon dates for five volcanic ash beds from the Global Stratotype Section and Point for the Permian-Triassic boundary at Meishan, China, define an age model for the extinction and allow exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, and recovery at millennial timescales. The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Mya, an interval of 60 ± 48 ka. Onset of a major reorganization of the carbon cycle immediately precedes the initiation of extinction and is punctuated by a sharp (3‰), short-lived negative spike in the isotopic composition of carbonate carbon. Carbon cycle volatility persists for ∼500 ka before a return to near preextinction values. Decamillenial to millennial level resolution of the mass extinction and its aftermath will permit a refined evaluation of the relative roles of rate-dependent processes contributing to the extinction, allowing insight into postextinction ecosystem expansion, and establish an accurate time point for evaluating the plausibility of trigger and kill mechanisms. PMID:24516148

High-precision timeline for Earth's most severe extinction.

PubMed

Burgess, Seth D; Bowring, Samuel; Shen, Shu-zhong

2014-03-04

The end-Permian mass extinction was the most severe loss of marine and terrestrial biota in the last 542 My. Understanding its cause and the controls on extinction/recovery dynamics depends on an accurate and precise age model. U-Pb zircon dates for five volcanic ash beds from the Global Stratotype Section and Point for the Permian-Triassic boundary at Meishan, China, define an age model for the extinction and allow exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, and recovery at millennial timescales. The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Mya, an interval of 60 ± 48 ka. Onset of a major reorganization of the carbon cycle immediately precedes the initiation of extinction and is punctuated by a sharp (3‰), short-lived negative spike in the isotopic composition of carbonate carbon. Carbon cycle volatility persists for ∼500 ka before a return to near preextinction values. Decamillenial to millennial level resolution of the mass extinction and its aftermath will permit a refined evaluation of the relative roles of rate-dependent processes contributing to the extinction, allowing insight into postextinction ecosystem expansion, and establish an accurate time point for evaluating the plausibility of trigger and kill mechanisms.

Astrochronology and magnetostratigraphy of the Xujiahe Formation of South China and Newark Supergroup of North America: implications for the Late Triassic time scale

NASA Astrophysics Data System (ADS)

Li, M.; Zhang, Y.; Huang, C.; Ogg, J. G.; Hinnov, L.; Wang, Y.; Zou, Z.; Li, L.; Grasby, S. E.; Zhong, Y.; Huang, K.

2017-12-01

The astrochronology derived from lacustrine clastic successions tied to the geomagnetic polarity time scale of the Newark Supergroup of eastern North America, known as the Newark APTS provides a basis for the Late Triassic time scale. However, the Newark APTS has been challenged regarding its age scale and completeness; therefore an independent astronomically tuned magnetic polarity zonation is required to verify the upper Newark APTS reference scale. We have compiled a 6.5 million year (myr) APTS with magnetic stratigraphy from four sections of the lacustrine-fluvial, dinosaur-track-bearing Xujiahe Formation in the Sichuan Basin of South China that has dating from detrital zircons and regional biostratigraphy. Variations in natural gamma-ray and magnetic susceptibility that reflect variable continental weathering in the source regions of the Xujiahe Formation are paced by Milankovitch cycles, especially the 100-kyr short eccentricity and 405-kyr long eccentricity. The cycle-tuned magnetostratigraphy of the Xujiahe Formation is compared directly via the magnetic-polarity zones to the depth ranks of the Newark Supergroup that are indicative of relative depositional depths of lacustrine facies. The Sichuan APTS indicates that there is no significant hiatus between the sedimentary succession and the basalt flows at the top of the Newark Supergroup. The Sichuan APTS is compatible with the magnetostratigraphy from the candidate Global Boundary Stratotype Section and Point (GSSP) for the Norian-Rhaetian boundary interval at the Pignola-Abriola section of South Italy, but does not extend downward to the proposed GSSP in Austria associated with the longer Rhaetian option. The earliest dinosaur tracks in China are from the middle of the Xujiahe Formation, therefore are implied to be middle Rhaetian in age. The Sichuan APTS helps to resolve the controversy about the completeness and reliability of the Newark APTS, and can be used in the future to verify if isotopic excursions in organic carbon recorded in the Italian sections that are proposed as possible secondary markers for a base-Rhaetian definition are global in nature. Ref. Li, M., Zhang, Y., Huang, C., et al., 2017, Earth Planet Sc Lett doi:10.1016/j.epsl.2017.07.015. Kent, D., Olsen, P., Muttoni, G., 2017. Earth-Sci Rev 166, 153-180.

Allostratigraphy of the U.S. middle Atlantic continental margin; characteristics, distribution, and depositional history of principal unconformity-bounded upper Cretaceous and Cenozoic sedimentary units

USGS Publications Warehouse

Poag, C. Wylie; Ward, Lauck W.

1993-01-01

Publication of Volumes 93 and 95 ('The New Jersey Transect') of the Deep Sea Drilling Project's Initial Reports completed a major phase of geological and geophysical research along the middle segment of the U. S. Atlantic continental margin. Relying heavily on data from these and related published records, we have integrated outcrop, borehole, and seismic-reflection data from this large area (500,000 km^2 ) to define the regional allostratigraphic framework for Upper Cretaceous and Cenozoic sedimentary rocks. The framework consists of 12 alloformations, which record the Late Cretaceous and Cenozoic depositional history of the contiguous Baltimore Canyon trough (including its onshore margin) and Hatteras basin (northern part). We propose stratotype sections for each alloformation and present a regional allostratigraphic reference section, which crosses these basins from the inner edge of the coastal plain to the inner edge of the abyssal plain. Selected supplementary reference sections on the coastal plain allow observation of the alloformations and their bounding unconformities in outcrop. Our analyses show that sediment supply and its initial dispersal on the middle segment of the U. S. Atlantic margin have been governed, in large part, by hinterland tectonism and subsequently have been modified by paleoclimate, sea-level changes, and oceanic current systems. Notable events in the Late Cretaceous to Holocene sedimentary evolution of this margin include (1) development of continental-rise depocenters in the northern part of the Hatteras basin during the Late Cretaceous; (2) the appear ance of a dual shelf-edge system, a marked decline in siliciclastic sediment accumulation rates, and widespread acceleration of carbonate production during high sea levels of the Paleogene; (3) rapid deposition and progradation of thick terrigenous delta complexes and development of abyssal depocenters during the middle Miocene to Quaternary interval; and (4) deep incision of the shelf edge by submarine canyons, especially during the Pleistocene. Massive downslope gravity flows have dominated both the depositional and erosional history of the middle segment of the U. S. Atlantic Continental Slope and Rise during most of the last 84 million years. The importance of periodic widespread erosion is recorded by well-documented unconformities, many of which can be traced from coastal-plain outcrops to coreholes on the continental slope and lower continental rise. These unconformities form the boundaries of the 12 allostratigraphic units we formally propose herein. Seven of the unconformities correlate with supercycle boundaries (sequence boundaries) that characterize the Exxon sequence-stratigraphy model.

Astronomical tuning and magnetostratigraphy of the Upper Triassic Xujiahe Formation of South China and Newark Supergroup of North America: Implications for the Late Triassic time scale

NASA Astrophysics Data System (ADS)

Li, Mingsong; Zhang, Yang; Huang, Chunju; Ogg, James; Hinnov, Linda; Wang, Yongdong; Zou, Zhuoyan; Li, Liqin

2017-10-01

The time scale of the Late Triassic Epoch has a divergence of age models, especially for the durations of competing definitions for its Rhaetian Stage (uppermost Triassic). The astrochronology derived from relative depth of lacustrine-bearing clastic successions and astronomically tuned geomagnetic polarity time scale (APTS) of the Newark Supergroup of eastern North America provides a basis for the Late Triassic time scale. However, the Newark APTS has been challenged regarding its age scale and completeness; therefore an independent astronomical-tuned magnetic polarity zonation is required to verify the upper Newark APTS reference scale. We compiled a 6.5 million year (myr) APTS with magnetic stratigraphy from four sections of the lacustrine-fluvial, dinosaur-track-bearing Xujiahe Formation in the Sichuan Basin of South China that also has dating from detrital zircons and regional biostratigraphy. Variations in natural gamma-ray and magnetic susceptibility that reflect variable continental weathering in the source regions of the Xujiahe Formation are paced by Milankovitch cycles, especially the 100-kyr short eccentricity and 405-kyr long eccentricity. The cycle-tuned magnetostratigraphy of the Xujiahe Formation is compared directly via the magnetic-polarity zones to the depth ranks of the Newark Supergroup that are indicative of relative depths of lacustrine facies. The Sichuan APTS indicates that there is no significant hiatus between the sedimentary succession and the basalt flows at the top of the Newark Supergroup. The Sichuan APTS is compatible with the magnetostratigraphy from the candidate Global Boundary Stratotype Section and Point (GSSP) for the Norian-Rhaetian boundary interval at the Pignola-Abriola of South Italy, but does not extend downward to the proposed GSSP in Austria associated with the longer Rhaetian option. The earliest dinosaur tracks in China are from the middle of this Xujiahe Formation, therefore are implied to be middle Rhaetian in age. This Sichuan APTS helps to resolve the controversy about the completeness and reliability of the Newark-APTS, and can be used in the future to verify if isotopic excursions in organic carbon recorded in the Italian sections that are proposed as possible secondary markers for a base-Rhaetian definition are global in nature.

The Mohawkian Chronostratigraphic Problem: building a reliable timescale by combining biostratigraphy, chemostratigraphy, and tephrochronology

NASA Astrophysics Data System (ADS)

Sell, B. K.; Sadler, P.; Leslie, S.; Mitchell, C.; Samson, S. D.

2011-12-01

The abundant exposures of Mohawkian (late Sandbian to early Katian) sedimentary rocks in eastern North America have been well-studied for insights into the Taconic orogeny and potential petroleum sources. Considerable information has been published toward establishing the sequence stratigraphic architecture, biozones for conodonts, graptolites and chitinozoans, chemostratigraphic correlations and a tephrochronologic framework. And yet, correlation remains difficult. Problems arise from complex sedimentary facies changes across the Laurentian margin and associated provincalism of the faunas. The difficulties are exacerbated by some imprecise usage of bentonite names, the short time spans of key stratigraphic sections, and a paucity of sections with muliple kinds of information. Also, linking so many taxon range end, ash-fall, and stable isotope excursion events into a coherent stratigraphic sequence is a daunting numerical problem. It falls into the notorious "NP-Complete" category because the number of possible solutions grows so fast as the number of events increases. "Simulated annealing" is one of the algorithms developed for such problems. We adopt it to solve the stratigraphic sequencing problem as a constrained optimization (CONOP). Nevertheless, to realize the full potential, more bentonite charactization and dating is needed in sections with detailed range charts for fossil species. CONOP works best with the individual taxon ranges, not the derived biozone boundaries. We examine the potential resolving power of CONOP in the context of a re-evaluation of bentonite correlations and newly acquired CA-TIMS U-Pb zircon dates from sections with rich biostratigraphic data. In particular we use 206Pb/238U zircon dates from two bentonites in the Womble Shale at the Katian Global Stratotype Section and Point (452.8 ± 0.2 and 453.5 ± 0.3 Ma, weighted mean with 2σ internal error) to compare various correlations with other dated bentonites in eastern North America. Preliminary dates for five long-range (>1000 km) bentonite correlations made on the basis of single-crystal apatite trace-element analyses (Mg, Cl, Mn, Fe, Ce, Y) help resolve previous conflicts among various biostratgraphic data, but raise new questions about the interpretation of stratigraphic sequences and chemostratigraphic data.

Rock Magnetic Cyclostratigraphy of the Mid-Cretaceous Greenhorn Limestone, South-Central Colorado---Influence of Orbitally Induced Climate Variability for Chornostratigraphy

NASA Astrophysics Data System (ADS)

Sellers, T.; Geissman, J. W.; Jackson, J.

2015-12-01

We are testing the hypothesis that depositional processes of the mid-Cretaceous Greenhorn Limestone were influenced by orbitally-driven climate variations using rock magnetic data. Correlation of the data, including anhysteretic remanent magnetization (ARM), magnetic susceptibility, isothermal remanent magnetization in different DC fields to saturation, and hysteresis properties, from three continuously exposed sections of the full Greenhorn Limestone provides detailed spatial distribution for the depositional processes and magnetic mineral climate encoding. The Greenhorn Limestone includes the Lincoln Limestone, Hartland Shale, and the Bridge Creek Limestone members and consists of calcareous shales and limestones representing near maximum depths in the Cretaceous interior seaway. The sections, each about 30 m thick, extend from the upper Graneros Shale, through the Greenhorn Formation, to the lower Carlisle Shale, with samples collected at a two to five cm interval and are located at Badito, CO; north of Redwing, CO; and at the Global boundary Stratotype Section and Point (GSSP) at Lake Pueblo, CO. Our over 1000 samples were hand crushed to granule size pieces and packed into 7cc IODP boxes. Bulk magnetic susceptibility, anhysteretic remanent magnetization (ARM) intensity at different peak AF levels, and isothermal remanent magnetization (IRM) intensity record variations in magnetic mineral concentration and are proxies to determine orbital scale cycles and precise stratigraphic correlation between sections. ARM intensities in a peak field of 100 mT at both sites range between 1.2 x 10-3 and 1.3 x 10-4 A/m and better define periodic variation within the Greenhorn Limestone displaying differences in ferromagnetic mineral content of detrital origin. Magnetic susceptibility, which ranges from 3.5 x 10-2 to 2.86 x 10-3, also shows periodic variation with a strong correlation among the three sections. Saturation IRM at 100 mT ranges from 3.2 x 10-1 to 1.1x 10-2 A/m shows periodic variation with the greatest variability in the Bridge Creek Member. Preliminary spectral analysis of each data set indicates a dominant cyclicity that is of considerably lower frequency than the limestone/shale couplets characteristic of Greenhorn Limestone.

Incised valley fill interpretation for Mississippian Black Hand Sandstone, Appalachian Basin, USA: Implications for glacial eustasy at Kinderhookian-Osagean (Tn2-Tn3) boundary

USGS Publications Warehouse

Matchen, D.L.; Kammer, T.W.

2006-01-01

Lower Mississippian strata of east-central Ohio are predominantly fine-grained marine deposits of the Cuyahoga and Logan formations. Within these sediments is the Black Hand Sandstone of the Cuyahoga Formation. The Black Hand Sandstone is a multistory, crossbedded, coarse-grained conglomeratic sandstone. The contact between the Black Hand Sandstone and the subjacent Cuyahoga Formation is sharp and scoured, with intraclasts of the Cuyahoga Formation incorporated into the basal Black Hand Sandstone. The Black Hand Sandstone was previously thought to represent a distributary channel deposit; however, the combination of lithofacies and architectural elements indicates deposition in a braided stream setting. The Cuyahoga Formation was deposited in a shallow marine setting. The erosional basal contact of the Black Hand Sandstone and the juxtaposition of fluvial and marine sediments suggests a sequence boundary. The geographic distribution of the Black Hand Sandstone combined with the evidence for a sequence boundary suggests deposition in an incised valley. The age of the Black Hand Sandstone is key to inferring the causes of valley incision. The Black Hand Sandstone is nearly devoid of body fossils, necessitating a biostratigraphic analysis of the surrounding Cuyahoga and Logan formations. Analysis indicates the Logan Formation is early Osagean age. Data from the Cuyahoga Formation suggest a Kinderhookian age with a possible transition to the Osagean in the uppermost Cuyahoga Formation. This constrains the age of the Black Hand Sandstone to the transition at the Kinderhookian-Osagean boundary. Recent reports indicate late Kinderhookian (Tournaisian, Tn2) Gondwanan glaciation based upon tillites and sharp excursions in stable-isotope curves. A glacio-eustatic fall in sea level is inferred to have caused incision of the Cuyahoga Formation, followed by deposition of the Black Hand Sandstone and Logan Formation during the subsequent sea level rise. The associated unconformity correlates to the sequence boundary at the Kinderhookian-Osagean boundary in the stratotype area of North America, and the correlative Tn2-Tn3 boundary worldwide, supporting the hypothesis of a global eustatic event at this time. ?? 2006 Elsevier B.V. All rights reserved.

The Massignano Eocene-Oligocene golden spike section revisited

NASA Astrophysics Data System (ADS)

van Mourik, C. A.; Brinkhuis, H.

2004-12-01

In common practice, the Eocene/Oligocene (E/O) boundary is linked to the Oi-1 δ 18 O benthic isotope event, reflecting the oldest phase of major Antarctic glaciation, calibrated against magnetosubchron C13n. Yet, the IUGS-ratified, current E/O GSSP at the pelagic Massignano Quarry section, central Italy, occurs within the older magnetosubchron C13r, at metre 19 of the 23 m section. To promote further high-resolution stratigraphic and paleoecological studies at Massignano, and to extend the lower Oligocene record, the so-called Massicore was drilled about 110 m south of the stratotype section. By means of high-resolution organic-walled dinoflagellate cyst (dinocyst) analysis, in combination with biotite-rich horizons an almost perfect linear correlation between the core and the quarry was obtained, resulting in the establishment of the Massignano GSSP composite section, spanning from magnetosubchron16-2n to 12r (van Mourik and Brinkhuis, in press). The revised paleomagnetic ages of this interval (Pḋ {a}like et al., in prep) were used for a preliminary age model of the composite section. The paleoecological dinocysts proxies were plotted along this agemodel. A straightforward correlation of the (relative) Sea Surface Temperature (SST) curve to the 400 ky eccentricity curve of Laskar et al.'s (2004) was possible. In two intervals (5.60 to 10.50 m and 17 to 35 m) the correlation could be made to the 100 ky eccentricity curve (Laskar et al., 2004). The first astronomical timescale for the Massignano GSSP composite section could be composed, placing the GSSP (19 m) at age of 33.96 ± 0.05 Ma. The age of the onset of the Oi-1 event appears around 33.55 ± 0.01 Ma, and towards the top of the section the cold peaks in the SST get more and more pronounced. The cooler conditions are substantiated by the occurrence of restricted high latitude dinocyst species (G. inflata and Sv. cooksoniae) from 33.30 ± 0.01 Ma until the top of the section (van Mourik et al., in prep). Relying also on earlier studies, we demonstrate that the current E/O GSSP criterion, the local extinction of the tropical genus Hantkenina (planktonic foraminifera) represents an isolated event, not suitable for global correlation. Instead, we argue that selection of the Oi-1 event as E/O criterion, which is also related to the TA4.3/4.4 third order sequence boundary, and the last occurrence of the dinocyst A. diktyoplokum) would provide a much better basis for global correlation. Moreover, selection of this slightly younger Oi-1 event criterion would place the top of the classic Priabonian Stage back in the latest Eocene, and the base of the Rupelian Stage in the earliest Oligocene. However, since the correlative level is not represented by the surface (quarry) section, but only resides in the cored, not exposed, section at Massignano, a new GSSP site should be selected, for example in one of the other central Italian sections that does span C13n (van Mourik and Brinkhuis, in press).

Tephrochronology and the extended intimate (integration of ice-core, marine and terrestrial records) event stratigraphy 8-128 ka b2k

NASA Astrophysics Data System (ADS)

Blockley, Simon P. E.; Bourne, Anna J.; Brauer, Achim; Davies, Siwan M.; Hardiman, Mark; Harding, Poppy R.; Lane, Christine S.; MacLeod, Alison; Matthews, Ian P.; Pyne-O'Donnell, Sean D. F.; Rasmussen, Sune O.; Wulf, Sabine; Zanchetta, Giovanni

2014-12-01

The comparison of palaeoclimate records on their own independent timescales is central to the work of the INTIMATE (INTegrating Ice core, MArine and TErrestrial records) network. For the North Atlantic region, an event stratigraphy has been established from the high-precision Greenland ice-core records and the integrated GICC05 chronology. This stratotype provides a palaeoclimate signal to which the timing and nature of palaeoenvironmental change recorded in marine and terrestrial archives can be compared. To facilitate this wider comparison, without assuming synchroneity of climatic change/proxy response, INTIMATE has also focussed on the development of tools to achieve this. In particular the use of time-parallel marker horizons e.g. tephra layers (volcanic ash). Coupled with the recent temporal extension of the Greenland stratotype, as part of this special issue, we present an updated INTIMATE event stratigraphy highlighting key tephra horizons used for correlation across Europe and the North Atlantic. We discuss the advantages of such an approach, and the key challenges for the further integration of terrestrial palaeoenvironmental records with those from ice cores and the marine realm.

A calcium isotope test of end-Permian ocean acidification using biogenic apatite

NASA Astrophysics Data System (ADS)

Hinojosa, J.; Brown, S. T.; DePaolo, D. J.; Paytan, A.; Shen, S.; Chen, J.; Payne, J.

2011-12-01

Submarine erosional truncation of uppermost Permian carbonate strata has been interpreted to reflect ocean acidification coincident with the end-Permian mass extinction. Although this scenario is consistent with carbon isotope and paleontological data, several alternative scenarios, such as ocean overturn or collapse of the biological pump, can also account for the carbon isotope and paleontological evidence. Calcium isotopes provide a geochemical proxy to test between acidification and alternative scenarios. Specifically, a negative shift in the calcium isotope composition (δ44/40Ca) of seawater is predicted under the acidification scenario but not the alternatives. The δ44/40Ca of carbonate rocks from south China exhibits a negative excursion of approximately 0.3%, but this shift could result from either a change in the δ44/40Ca of seawater or a change in carbonate mineralogy because calcite and aragonite exhibit substantially different fractionation factors relative to seawater. To test whether the negative shift in δ44/40Ca reflects seawater δ44/40Ca or carbonate mineralogy, we measured the δ44/40Ca of conodont microfossils (calcium hydroxyapatite) from the global stratotype section for the Permian-Triassic boundary at Meishan, China. The conodont δ44/40Ca record shows a negative excursion similar in stratigraphic position and magnitude to that previously observed in carbonate rocks. Parallel negative excursions in the δ44/40Ca of carbonate rocks and conodont microfossils cannot be accounted for by a change in carbonate mineralogy but are consistent with a negative shift in the δ44/40Ca of seawater. These data add further support for the ocean acidification scenario, pointing toward strong similarities between the greatest catastrophe in the history of animal life and anticipated global change during the 21st century.

Short-term survival of ammonites in New Jersey after the end-Cretaceous bolide impact

USGS Publications Warehouse

Landman, Neil H.; Garb, Matthew P.; Rovelli, Remy; Ebel, Denton S.; Edwards, Lucy E.

2012-01-01

A section containing the Cretaceous/Paleogene (= Cretaceous/Tertiary) boundary in Monmouth County, New Jersey, preserves a record of ammonites extending from the end of the Cretaceous into possibly the beginning of the Danian. The section includes the upper part of the Tinton Formation and lower part of the Hornerstown Formation. The top of the Tinton Formation is represented by a richly fossiliferous unit (the Pinna Layer) that contains many bivalves in life position as well as ammonite jaws preserved inside body chambers. Ammonites include Pachydiscus (Neodesmoceras) mokotibensis, Sphenodiscus lobatus, Eubaculites carinatus, E. latecarinatus; Discoscaphites iris, D. sphaeroidalis; D. minardi, and D. jerseyensis. The Pinna Layer probably represents a relatively short interval of time lasting tens to hundreds of years; it is conformably overlain by the Burrowed Unit, which contains a single fragment of Discoscaphites sp. and several fragments of E. latecarinatus, as well as several isolated specimens of ammonite jaws including two of Eubaculites. Examination of the mode of preservation of the ammonites and jaws suggests that they were fossilized during deposition of the Burrowed Unit and were not reworked from older deposits. Based on the ammonites and dinoflagellates in the Pinna Layer and the Burrowed Unit, these strata traditionally would be assigned to the uppermost Maastrichtian, corresponding to calcareous nannofossil Subzone CC26b. However, a weak iridium anomaly (500–600 pg/g) is present at the base of the Pinna Layer, which presumably represents the record of the bolide impact. Correlation with the iridium layer at the Global Stratotype Section and Point at El Kef, Tunisia, would, therefore, imply that these assemblages are actually Danian, provided that the iridium anomaly is in place and the ammonites and dinoflagellates are not reworked. If the iridium anomaly is in place, or even if it has migrated downward from the top of the Pinna Layer, the ammonites would have survived the impact at this site for a brief interval of time lasting from a few days to hundreds of years.

New data on Callovian (Middle Jurassic) belemnites and palynomorphs from the Northern Caucasus, southwest Russia

NASA Astrophysics Data System (ADS)

Dzyuba, Oksana S.; Goryacheva, Anna A.; Ruban, Dmitry A.; Gnezdilova, Victoria V.; Zayats, Pavel P.

2016-03-01

Palaeontological data on the Caucasus are highly important for large-scale stratigraphical and palaeobiogeographical assessment of the northern Tethyan margin, but this information is often scarce and not available in English. Field studies in the Northern Caucasus have now permitted to amass some new data. Two belemnite species are described from the stratotype section of the Kamennomostskaja Formation (Callovian, Middle Jurassic) near the town of Kamennomostskij in Adygeja (Northern Caucasus). These are Belemnopsis subhastata (von Zieten, 1831) and Rhopaloteuthis ominosa Gustomesov, 1968. The latter is a rare species, and the present find allows new insights into its taxonomy. A palyno-logical analysis of the belemnite-bearing sample was carried out, and a diverse assemblage of dinocysts, acritarchs and prasinophytes, plus pollen and spores recognised. The most abundant palynomorphs are Micrhystridium and Classopollis. Data on belemnites coupled with those on palynomorphs indicate the early Callovian age of the sample level. This interpretation differs slightly from previous conclusions based on ammonites and dinocysts. If this age is correct, the degree of condensation of Callovian deposits in the section studied was lesser than previously assumed.

Benthic foraminiferal assemblages: a clue to the palaeoecology and palaeoenvironment of the Pliensbachian- Toarcian transition of Peniche (Lusitanian Basin, Portugal)

NASA Astrophysics Data System (ADS)

Rita, Patrícia; Reolid, Matias; Duarte, Luís V.

2015-04-01

The Lower Jurassic of the Peniche region (Lusitanian Basin, Portugal) constitutes one of the most worldwide references concerning the stratigraphy of the Lower Toarcian. In fact, the Peniche Section is the unique candidate to the Toarcian Global Boundary Stratotype Section and Point and records some important evidences about the palaeoenvironmental perturbations associated to the Toarcian Oceanic Anoxic Event (T-OAE) (e.g. Hesselbo et al., 2007). Despite the large number of micropaleontological studies developed in this section (e.g. ostracods, calcareous nannofossils), any relevant study of benthic foraminifera has been presented, even to the whole basin scale. Thus, based on a detailed stratigraphic analysis that includes 39 marly samples of the Emaciatum (= Spinatum) - Levisoni (= Serpentinum) ammonite zone interval (around 37 m thick), the aim of this work is the study of the foraminiferal assemblages from the Pliensbachian-Toarcian boundary and across the T-OAE. The results and main conclusions of this preliminary study show three different stages: 1) The uppermost Pliensbachian (Emaciatum Zone) is characterized by foraminiferal assemblages with high diversity and abundance (foram/g) dominated by Marginulina, Lenticulina, Dentalina and Ammobaculites, suggesting well-oxygenation and nutrient availability. 2) The beginning of the Toarcian (Polymorphum Zone) evidences a drastic decrease of the diversity and abundance of the foraminiferal assemblages. 3) This trend continues in the Levisoni Zone with decreasing diversity and abundance (some barren samples are recorded), but opportunistic forms such as Epistomina and Lenticulina, occasionally proliferate. This evolution suggests a clear perturbation in the palaeocological conditions at the sea-bottom during the Early Toarcian, feature that is observed in other basins (see Reolid et al., 2012). The fluctuations of foraminiferal assemblages recorded across the studied interval seems to correlate with the previous sequence stratigraphic interpretation of the series (e.g. Duarte, 2007) and the proliferation of opportunistic forms in some levels could be a reflex of the turbiditic sedimentation that took place in this area during this period (Wright & Wilson, 1984), which promotes the oxygenation of the sea-bottom. References Duarte, L.V. (2007). In R. B. Rocha (Ed.): The Peniche section (Portugal). Contributions to the definition of the Toarcian GSSP. International Subcommission on Jurassic Stratigraphy, ISBN 978-972-8893-14-9, 17-23; Hesselbo, S. P., Kenkyns, H. C., Duarte, L.V., Oliveira, L. C. V. (2007). Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal). Earth and Planetary Science Letters, 253: 455-470. Reolid, M., Sebane, A., Rodríguez-Tovar, F. J., Marok, A. (2012). Foraminiferal morphogroups as a tool to approach the Toarcian Anoxic Event in the Western Saharan Atlas (Algeria). Palaeogeography Palaeoclimatology Palaeoecology, 323-325: 87-99. Wright, V.P. & Wilson, R.C.L. (1984). A carbonate submarine-fan sequence from the Jurassic of Portugal, Journal of Sedimentary Petrology, 54: 394-412.

Global Peak in Atmospheric Radiocarbon Provides a Potential Definition for the Onset of the Anthropocene Epoch in 1965.

PubMed

Turney, Chris S M; Palmer, Jonathan; Maslin, Mark A; Hogg, Alan; Fogwill, Christopher J; Southon, John; Fenwick, Pavla; Helle, Gerhard; Wilmshurst, Janet M; McGlone, Matt; Bronk Ramsey, Christopher; Thomas, Zoë; Lipson, Mathew; Beaven, Brent; Jones, Richard T; Andrews, Oliver; Hua, Quan

2018-02-19

Anthropogenic activity is now recognised as having profoundly and permanently altered the Earth system, suggesting we have entered a human-dominated geological epoch, the 'Anthropocene'. To formally define the onset of the Anthropocene, a synchronous global signature within geological-forming materials is required. Here we report a series of precisely-dated tree-ring records from Campbell Island (Southern Ocean) that capture peak atmospheric radiocarbon ( 14 C) resulting from Northern Hemisphere-dominated thermonuclear bomb tests during the 1950s and 1960s. The only alien tree on the island, a Sitka spruce (Picea sitchensis), allows us to seasonally-resolve Southern Hemisphere atmospheric 14 C, demonstrating the 'bomb peak' in this remote and pristine location occurred in the last-quarter of 1965 (October-December), coincident with the broader changes associated with the post-World War II 'Great Acceleration' in industrial capacity and consumption. Our findings provide a precisely-resolved potential Global Stratotype Section and Point (GSSP) or 'golden spike', marking the onset of the Anthropocene Epoch.

Ice-volume-forced erosion of the Chinese Loess Plateau global Quaternary stratotype site.

PubMed

Stevens, T; Buylaert, J-P; Thiel, C; Újvári, G; Yi, S; Murray, A S; Frechen, M; Lu, H

2018-03-07

The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time. The reliability of these records is fundamental to understand past global change. Here we use the most detailed luminescence dating age model yet published to show that the ICS chronology for the Quaternary terrestrial type section at Jingbian, desert marginal Chinese Loess Plateau, is inaccurate. There are large hiatuses and depositional changes expressed across a dynamic gully landform at the site, which demonstrates rapid environmental shifts at the East Asian desert margin. We propose a new independent age model and reconstruct monsoon climate and desert expansion/contraction for the last ~250 ka. Our record demonstrates the dominant influence of ice volume on desert expansion, dust dynamics and sediment preservation, and further shows that East Asian Summer Monsoon (EASM) variation closely matches that of ice volume, but lags insolation by ~5 ka. These observations show that the EASM at the monsoon margin does not respond directly to precessional forcing.

Anthropocene: Shifting Paradigms in Geoscience, Philosophy, History and Geopolitics

NASA Astrophysics Data System (ADS)

Maslin, M. A.; Lewis, S. L.

2015-12-01

The concept of the Anthropocene has created a profound paradigm shift within the scientific community that we argue will create equally important changes in philosophy, history and politics. There is general scientific agreement that human activity has been a geologically recent, yet profound, influence on the Earth System. The magnitude, variety and longevity of human-induced changes, to the lithosphere, hydrosphere, cryosphere, biosphere and atmosphere suggests that we should refer to the present, not as within the Holocene Epoch (as it is currently formally referred to), but instead as within the Anthropocene Epoch. Discussion is now centred on defining the start of the epoch using the fundamental principles of stratigraphy. These must include (i) a near permanent change to the Earth system that sets it on to a new trajectory and (ii) global changes to the Earth system recorded in a number of stratigraphic deposits worldwide to provide a correlative boundary event or marker called a Global Stratotype Section & Point (GSSP) or 'golden spike'. Using this framework we conclude that just two time-periods are likely adhere to the criteria. These are 1) the irreversible cross-ocean exchange of species alongside the globally synchronous coolest part of the Little Ice Age in the 17th century, marked by the 1610 minima of CO2 (Orbis Spike), and 2) the accelerating atmospheric, oceanic and terrestrial changes in the second half of the 20th century, referred to as the Great Acceleration and conveniently marked by the 1964 peak radionuclide fallout (Bomb Spike). We seek to clear up misconceptions and misunderstandings about geological criteria and relevant evidence that have crept into the literature. We also argue that there are multiple definitions of the Anthropocene and even if a formal definition of the Anthropocene Epoch is agreed by geoscientists, this would in no way invalidate other definitions or uses. It is the utility and wide appeal that makes the Anthropocene such an important concept.

Upper Cretaceous to Lower Miocene of the Subsilesian Unit (Western Carpathians, Czech Republic): stratotypes of formations revised

NASA Astrophysics Data System (ADS)

Bubík, Miroslav; Franců, Juraj; Gilíková, Helena; Otava, Jiří; Švábenická, Lilian

2016-06-01

Type sections/areas for all four formations distinguished in the sedimentary succession of the Subsilesian Unit on Czech territory were revisited and described. New data on lithology, sedimentology, fossil record, biostratigraphy, heavy-minerals and geochemical proxies are based on observations and analysis of these sections. The historical type section of the Frýdek Formation was destroyed during railway construction in 19th century. Outcrops of Campanian to Maastrichtian marls and sandstones on the southwestern slope of "Castle hill" at Frýdek, are proposed as a new type section. The Ostravice riverbed in Frýdlant nad Ostravicí was originally designated as the type area, not mentioning the particular section. This area, even when supplemented with Sibudov Creek, does not show all typical facies of the formation. The outcrops range from lowermost Eocene to Eocene-Oligocene transition. In the original description of the Menilite Formation Glocker mentioned several localities in the area covering the Ždanice, Subsilesian and Silesian units, not mentioning the principal one. The single sections, each not exceeding a thickness of 2 m, are not sufficient to be a type section. Instead of that, we propose the area between Paršovice and Bystřice pod Hostýnem, covering the historical localities, as the type area. The type locality of the Ženklava Formation is an outcrop in an unnamed creek in Ženklava according to the original definition. It seems to be reasonable to extend the type section to the whole 500 m long section of the creek with the outcrops that better illustrate the lithological variability of the formation. New biostratigraphic data allow assignment to late Egerian (Eggenburgian?).

Stratigraphy and facies development of the marine Late Devonian near the Boulongour Reservoir, northwest Xinjiang, China

NASA Astrophysics Data System (ADS)

Suttner, Thomas J.; Kido, Erika; Chen, Xiuqin; Mawson, Ruth; Waters, Johnny A.; Frýda, Jiří; Mathieson, David; Molloy, Peter D.; Pickett, John; Webster, Gary D.; Frýdová, Barbora

2014-02-01

Late Devonian to Early Carboniferous stratigraphic units within the 'Zhulumute' Formation, Hongguleleng Formation (stratotype), 'Hebukehe' Formation and the Heishantou Formation near the Boulongour Reservoir in northwestern Xinjiang are fossil-rich. The Hongguleleng and 'Hebukehe' formations are biostratigraphically well constrained by microfossils from the latest Frasnian linguiformis to mid-Famennian trachytera conodont biozones. The Hongguleleng Formation (96.8 m) is characterized by bioclastic argillaceous limestones and marls (the dominant facies) intercalated with green spiculitic calcareous shales. It yields abundant and highly diverse faunas of bryozoans, brachiopods and crinoids with subordinate solitary rugose corals, ostracods, trilobites, conodonts and other fish teeth. The succeeding 'Hebukehe' Formation (95.7 m) consists of siltstones, mudstones, arenites and intervals of bioclastic limestone (e.g. 'Blastoid Hill') and cherts with radiolarians. A diverse ichnofauna, phacopid trilobites, echinoderms (crinoids and blastoids) together with brachiopods, ostracods, bryozoans and rare cephalopods have been collected from this interval. Analysis of geochemical data, microfacies and especially the distribution of marine organisms, which are not described in detail here, but used for facies analysis, indicate a deepening of the depositional environment at the Boulongour Reservoir section. Results presented here concern mainly the sedimentological and stratigraphical context of the investigated section. Additionally, one Late Devonian palaeo-oceanic and biotic event, the Upper Kellwasser Event is recognized near the section base.

Learning to tell Neoproterozoic time

NASA Technical Reports Server (NTRS)

Knoll, A. H.

2000-01-01

In 1989, the International Commission on Stratigraphy established a Working Group on the Terminal Proterozoic Period. Nine years of intensive, multidisciplinary research by scientists from some two dozen countries have markedly improved the framework for the correlation and calibration of latest Proterozoic events. Three principal phenomena--the Marinoan ice age, Ediacaran animal diversification, and the beginning of the Cambrian Period--specify the limits and character of this interval, but chemostratigraphy and biostratigraphy based on single-celled microfossils (acritarchs), integrated with high-resolution radiometric dates, provide the temporal framework necessary to order and evaluate terminal Proterozoic tectonic, biogeochemical, climatic, and biological events. These data also provide a rational basis for choosing the Global Stratotype Section and Point (GSSP) that will define the beginning of this period. A comparable level of stratigraphic resolution may be achievable for the preceding Cryogenian Period, providing an opportunity to define this interval, as well, in chronostratigraphic terms--perhaps bounded at beginning and end by the onset of Sturtian glaciation and the decay of Marinoan ice sheets, respectively. Limited paleontological, isotopic, and radiometric data additionally suggest a real but more distant prospect of lower Neoproterozoic correlation and stratigraphic subdivision.

Cenomanian-Turonian transition in a shallow water sequence of the Sinai, Egypt

NASA Astrophysics Data System (ADS)

Gertsch, B.; Keller, G.; Adatte, T.; Berner, Z.; Kassab, A. S.; Tantawy, A. A. A.; El-Sabbagh, A. M.; Stueben, D.

2010-01-01

Environmental and depositional changes across the Late Cenomanian oceanic anoxic event (OAE2) in the Sinai, Egypt, are examined based on biostratigraphy, mineralogy, δ13C values and phosphorus analyses. Comparison with the Pueblo, Colorado, stratotype section reveals the Whadi El Ghaib section as stratigraphically complete across the late Cenomanian-early Turonian. Foraminifera are dominated by high-stress planktic and benthic assemblages characterized by low diversity, low-oxygen and low-salinity tolerant species, which mark shallow-water oceanic dysoxic conditions during OAE2. Oyster biostromes suggest deposition occurred in less than 50 m depths in low-oxygen, brackish, and nutrient-rich waters. Their demise prior to the peak δ13C excursion is likely due to a rising sea-level. Characteristic OAE2 anoxic conditions reached this coastal region only at the end of the δ13C plateau in deeper waters near the end of the Cenomanian. Increased phosphorus accumulations before and after the δ13C excursion suggest higher oxic conditions and increased detrital input. Bulk-rock and clay mineralogy indicate humid climate conditions, increased continental runoff and a rising sea up to the first δ13C peak. Above this interval, a dryer and seasonally well-contrasted climate with intermittently dry conditions prevailed. These results reveal the globally synchronous δ13C shift, but delayed effects of OAE2 dependent on water depth.

The Lindi Formation (upper Albian-Coniacian) and Tanzania Drilling Project Sites 36-40 (Lower Cretaceous to Paleogene): Lithostratigraphy, biostratigraphy and chemostratigraphy

NASA Astrophysics Data System (ADS)

Jiménez Berrocoso, Álvaro; Huber, Brian T.; MacLeod, Kenneth G.; Petrizzo, Maria Rose; Lees, Jacqueline A.; Wendler, Ines; Coxall, Helen; Mweneinda, Amina K.; Falzoni, Francesca; Birch, Heather; Haynes, Shannon J.; Bown, Paul R.; Robinson, Stuart A.; Singano, Joyce M.

2015-01-01

The 2009 Tanzania Drilling Project (TDP) expedition to southeastern Tanzania cored a total of 572.3 m of sediments at six new mid-Cretaceous to mid-Paleocene boreholes (TDP Sites 36, 37, 38, 39, 40A, 40B). Added to the sites drilled in 2007 and 2008, the new boreholes confirm the common excellent preservation of planktonic and benthic foraminifera and calcareous nannofossils from core samples that will be used for biostratigraphy, evolutionary studies, paleoceanography and climatic reconstructions from the Tanzanian margin, with implications elsewhere. The new sites verify the presence of a relatively expanded Upper Cretaceous succession in the region that has allowed a new stratigraphic unit, named here as the Lindi Formation (Fm), to be formally defined. The Lindi Fm (upper Albian to Coniacian), extending ∼120 km between Kilwa and Lindi, comprises a 335-m-thick, outer-shelf to upper-slope unit, consisting of dark gray claystone and siltstone interbeds, common finely-laminated intervals, minor cm-thick sandstones and up to 2.6% organic carbon in the Turonian. A subsurface, composite stratotype section is proposed for the Lindi Fm, with a gradational top boundary with the overlying Nangurukuru Fm (Santonian to Maastrichtian) and a sharp bottom contact with underlying upper Albian sandstones. The section cored at TDP Sites 36 and 38 belongs to the Lindi Fm and are of lower to middle Turonian age (planktonic foraminifera Whiteinella archaeocretacea to Helvetoglobotruncana helvetica Zones and nannofossils subzones UC6b ± UC7). The lower portion of TDP Site 39 (uppermost part of the Lindi Fm) is assigned to the lower to upper Coniacian (planktonic foraminifera Dicarinella concavata Zone and nannofossils zone UC 10), while the remaining part of this site is attributed to the Coniacian-Santonian transition and younger Santonian (planktonic foraminifera D. asymetrica Zone and upper part of nannofossils zone UC10). TDP Site 37 recovered relatively expanded (150 m thick), monotonous calcareous claystones from the lower to upper Maastrichtian (planktonic foraminifera Pseudoguembelina palpebra to Abathomphalus mayaroensis Zones and nannofossils zones UC19 to UC20aTP) that were separated by a hiatus and/or a faulted contact from overlying brecciated carbonates of the Selandian (middle Paleocene: PF Zone P3 and nannofossil zone NP5). The lower portion of TDP Sites 40A and 40B recovered sandstones and conglomerates barren of microfossils. Their overlying parts were assigned to incomplete sections of the nannofossil zones NC6A to NC8 (uppermost Barremian to lower Albian). Benthic foraminiferal assemblages allowed the Barremian to lower Aptian to be identified in TDP Sites 40A and 40B, while the upper Aptian to middle Albian (Hedbergella trocoidea to Ticinella primula Zones) were assigned using planktonic foraminifera. Cores recovered at TDP 39 (Coniacian-Santonian) and at TDP Sites 40A and 40B (Barremian-middle Albian) represent the first time that these two intervals have been continuously cored and publicly documented in Tanzania. Bulk sediment isotope records generated for the new sites show lower δ18Ocarb values in the Turonian and Santonian (∼-3.5‰ to -5‰) than in the Maastrichtian (∼-3‰), a situation consistent with extreme global warmth in the older intervals and cooling toward the end of the Cretaceous. Also, similar to Turonian sites from previous TDP expeditions, a negative δ13Corg excursion was detected across the W. archaeocretacea-H. helvetica boundary of TDP Site 36 (close to, but above, the Cenomanian-Turonian boundary). This excursion probably responded to local processes in the region, but it is unknown whether they were related to the recovery phase from Ocean Anoxic Event 2.

The Miocene Extraterrestrial Dust Deposition Event Tracked by Helium, Neon, Chromium and Extraterrestrial Insoluble Organic Matter at the Monte Dei Corvi Beach Section

NASA Astrophysics Data System (ADS)

Meier, M. M. M.; Steele, R. C. J.; Schmitz, B.; Piani, L.; Maden, C.; Plant, A. A.; Schönbächler, M.; Busemann, H.

2017-12-01

A temporarily increased flux of extraterrestrial dust to Earth can lead to tell-tale clues in sediments of the same age. A common example is peaks of 3He in sediments, which occur because extraterrestrial material is rich in implanted solar wind that has a high 3He/4He ratio compared to the atmosphere. One of two known 3He-peaks in Cenozoic sediments is found within the Miocene, at an age of about 8 Ma (Tortonian stage). This peak has been tied to the asteroid break-up event which formed the Veritas family (Farley et al., Nature, 2006). The Global Boundary Stratotype Section and Point for the Tortonian is located near Monte Dei Corvi, in Ancona, Italy. It has previously been well characterized using both magneto- and cyclostratigraphy (Hüsing et al., EPSL, 2009), and can thus provide excellent time-constraints on the age of the event, now dated to have started at 8.47±0.05 Ma (Montanari et al., GSA Bulletin, 2017). In this project, we study these sediments with the primary goal of determining the meteoritic type of the extraterrestrial dust. We have been following three different avenues towards that goal: (1) light noble gas (He, Ne) analyses of bulk sediments (Meier et al., Annual Meeting of the Meteoritical Society, 2016), which are used as tracers of dust flux. The measured He vs. Ne allows us to characterize the preservation state of the extraterrestrial noble gases in the sediments (see Chavrit et al., EPSL, 2016); (2) Cr abundance and isotope analysis of bulk sediments and residues, which should allow us to determine the meteoritic type of the deposited dust (e.g., Rotaru et al., Nature, 1992); (3) an attempt to isolate and characterize potentially surviving meteoritic organic matter in the bulk sediments from Monte Dei Corvi. Insoluble organic matter, which contributes 1-2% of the mass in some carbonaceous chondrites (tied to C- and D-type asteroids, like the ones found abundantly in the Veritas family; Ziffer et al., Icarus, 2011) is strongly acid- and temperature-resistant, and shows D/H and 14N/15N isotopic anomalies (e.g., Piani et al., EPSL, 2015). It thus has potential as a new tracer for dust deposition events from carbonaceous chondrite parent asteroids. We will provide an update for all three projects at the conference.

Stratotype for the Mérida Glaciation at Pueblo Llano in the northern Venezuelan Andes

NASA Astrophysics Data System (ADS)

Mahaney, W. C.; Milner, M. W.; Voros, J.; Kalm, V.; Hütt, G.; Bezada, M.; Hancock, R. G. V.; Aufreiter, S.

2000-12-01

The Mérida Glaciation (cf. Wisconsinan, Weichselian) as proposed by Schubert (1974b) culminated at about 18 ka during the last glacial maximum (LGM) and ended at about 13 ka as indicated by 14C dating and correlation with the Cordillera Oriental of Colombia. Moraines of an early stade of Mérida Glaciation reached to 2800 m a.s.l. and were largely overrun or eradicated by the maximum Wisconsinan advance (LGM); where they outcrop, the older moraines are characterized by eroded, weathered glacial diamictons and outwash fans. At Pueblo Llano in the central Mérida Andes (Cordillera de Trujillo), older to younger beds of contorted glacitectonized diamict, overlying beds of bouldery till and indurated outwash, all belong to the early Mérida stade. Overlying the early Mérida stade, deposits of rhythmically bedded glaciolacustrine sediments are in turn overlain with contorted sand and silt beds capped with outwash. Above the outwash terrace a loop moraine of LGM age completely encircles the margins of the basin. A stream cut exposed by catastrophic (tectonic or surge?) release of meltwater displays a lithostratigraphic succession that is bereft of organic material for radiocarbon dating. Five optically-stimulated luminescence (OSL) dates place the maximum age of the lowest till at 81 ka. Particle size distributions allow clear distinctions between major lithic units. Heavy mineral analysis of the middle and lower coarse units in the section provide information on sediment sourcing and on major lithostratigraphic divisions. Trace element concentrations provide information on the relative homogeneity of the deposits. The HREE (heavy rare earth element) concentrations allow discrimination of the lower till from the rest of the section; the LREE (light rare earth element) concentrations highlight differences between the lower till, LGM till, and the rest of the section.

OWL representation of the geologic timescale implementing stratigraphic best practice

NASA Astrophysics Data System (ADS)

Cox, S. J.

2011-12-01

The geologic timescale is a cornerstone of the earth sciences. Versions are available from many sources, with the following being of particular interest: (i) The official International Stratigraphic Chart (ISC) is maintained by the International Commission for Stratigraphy (ICS), following principles developed over the last 40 years. ICS provides the data underlying the chart as part of a specialized software package, and the chart itself as a PDF using the standard colours; (ii) ITC Enschede has developed a representation of the timescale as a thesaurus in SKOS, used in a Web Map Service delivery system; (iii) JPL's SWEET ontology includes a geologic timescale. This takes full advantage of the capabilities of OWL. However, each of these has limitations - The ISC falls down because of incompatibility with web technologies; - While SKOS supports multilingual labelling, SKOS does not adequately support timescale semantics, in particular since it does not include ordering relationships; - The SWEET version (as of version 2) is not fully aligned to the model used by ICS, in particular not recognizing the role of the Global Boundary Stratotype Sections and Point (GSSP). Furthermore, it is distributed as static documents, rather than through a dynamic API using SPARQL. The representation presented in this paper overcomes all of these limitations as follows: - the timescale model is formulated as an OWL ontology - the ontology is directly derived from the UML representation of the ICS best practice proposed by Cox & Richard [2005], and subsequently included as the Geologic Timescale package in GeoSciML (http://www.geosciml.org); this includes links to GSSPs as per the ICS process - key properties in the ontology are also asserted to be subProperties of SKOS properties (topConcept and broader/narrower relations) in order to support SKOS-based queries; SKOS labelling is used to support multi-lingual naming and synonyms - the International Stratigraphic Chart is implemented as a set of instances of classes from the ontology, and published through a SPARQL end-point - the elements of the Stratigraphic chart are linked to the corresponding elements in SWEET (Raskin et al., 2011) and DBpedia to support traceability between different commonly accessed representations. The ontology builds on standard geospatial information models, including the Observations and Measurements model (ISO 19156), and GeoSciML. This allows the ages given in the chart to be linked to the evidence basis found in the associated GeoSciML features.

76 FR 19124 - United States Section, Notice of Availability of a Draft Supplemental Environmental Assessment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-06

... INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO United States Section... States Section, International Boundary and Water Commission, United States and Mexico (USIBWC). ACTION..., Environmental Management Division, United States Section, International Boundary and Water Commission; 4171 N...

75 FR 77662 - United States Section; Notice of Availability of a Final Environmental Assessment and Finding of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-13

... INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO United States Section... States Section, International Boundary and Water Commission, United States and Mexico (USIBWC). ACTION... States Section, International Boundary and Water Commission; 4171 N. Mesa, C-100; El Paso, Texas 79902...

Faunal and erosional events in the Eastern Tethyan Sea across the K/T boundary

NASA Technical Reports Server (NTRS)

Keller, G.; Benjamini, C.

1988-01-01

A regional pattern of three closely spaced erosional events at and above the K/T boundary was determined from six Cretaceous/Tertiary boundary sections in the Negev of Israel. The sections were collected from locations throughout the central and northern Negev. All sections are lithologically similar. The Maastrichtian consists of a sequence of limestone beds intercalated with thin marly beds. In some sections, the last limestone bed is followed by 1 to 2 m of calcareous marls grading upwards into several meters of grey shale. In other sections the limestone bed is followed directly by grey shale with the contact containing particles of limestone and marl. A 5 to 20 cm thick dark grey organic-rich clay layer is present about 1.5 to 2.5 m above the base of the grey shale. The grey shale grades upwards into increasingly carbonate rich marls. No unconformities are apparent in field outcrops. During field collection the dark grey clay layer was believed to represent the K/T boundary clay. Microfossil analysis however identified the boundary at the base of the grey shale. The black shale represents a low productivity anoxic event similar to, but younger than, the K/T boundary clay in other K/T boundary sections. High resolution planktic foraminiferal and carbonate analysis of these sections (at 5 to 10 cm intervals) yield surprising results. The K/T boundary is marked by an erosional event which removed part or all of the uppermost Maastrichtian marls above the last limestone bed. Percent carbonate data for four Negev sections are illustrated and show the regional similarities in carbonate sedimentation. Faunal and carbonate data from the Negev sections thus show three closely spaced short erosional events at the K/T boundary and within the first 50,000 to 100,000 years of the Danian. These K/T boundary erosional events may represent global climatic or paleoceanographic events.

Conodont biostratigraphy of a more complete Reef Trail Member section near the type section, latest Guadalupian Series type region

USGS Publications Warehouse

Wardlaw, Bruce R.; Lambert, L.L.; Bell, G.L.; Fronimos, J.A.; Yisa, M.O.

2010-01-01

The original type section of the Reef Trail Member (uppermost part of the Bell Canyon Formation) is called the Park Boundary Section, and is less than satisfactory in several aspects. We propose a new reference section designated Reef Trail Reference section 1 (RTR1) on the same hill as the original type section. Section RTR1 compensates for some of the Park Boundary Section’s shortcomings, including better exposure of a single measured section with only minor offset. The conodont biostratigraphy of section RTR1 is presented that, when combined with a better set of described correlation intervals, allows for improved correlation to recently discovered, complete, basinal sections in the Patterson Hills. In comparison with the South Boundary basin section, both the Park Boundary and RTR1 sections are missing approximately the upper third of the Reef Trail Member. Transitional conodonts from the basin demonstrate that Jinogondolella crofti evolved directly from J. altudaensis. We formally elevate Clarkina postbitteri hongshuiensis to C. hongshuiensis.

3 CFR - Designation of Officers of the United States Section, International Boundary and Water Commission...

Code of Federal Regulations, 2010 CFR

2010-01-01

..., International Boundary and Water Commission, United States and Mexico To Act as the Commissioner of the United... States and Mexico To Act as the Commissioner of the United States Section Memorandum for the Commissioner of the United States Section, International Boundary and Water Commission, United States and Mexico...

An experimental investigation of a two and a three-dimensional low speed turbulent boundary layer

NASA Technical Reports Server (NTRS)

Winkelmann, A. E.; Melnik, W. L.

1976-01-01

Experimental studies of a two and a three-dimensional low speed turbulent boundary layer were conducted on the side wall of a boundary layer wind tunnel. The 20 ft. long test section, with a rectangular cross section measuring 17.5 in. x 46 in., produced a 3.5 in. thick turbulent boundary layer at a free stream Reynolds number. The three-dimensional turbulent boundary layer was produced by a 30 deg swept wing-like model faired into the side wall of the test section. Preliminary studies in the two-dimensional boundary layer indicated that the flow was nonuniform on the 46 in. wide test wall. The nonuniform boundary layer is characterized by transverse variations in the wall shear stress and is primarily caused by nonuniformities in the inlet damping screens.

27 CFR 9.153 - Redwood Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Highway 20 with the eastern boundary of Section 13, T16N/R12W located in the extreme northeast portion of....S. map, “Laughlin, Range, Calif.”; (7) Then south along the western boundary line of Sections 1 and... beginning point at the eastern boundary of Section 13, T16N/R12W located in the extreme northeast portion of...

Nature of the Paleocene/Eocene (P/E) boundary in Sinai, Egypt

NASA Astrophysics Data System (ADS)

Obaidalla, Nageh A.; Abdel-Maksoud, Nasr A.; Hosny, Atef M.; Mahfouz, Kamel H.

2017-12-01

The P/E boundary is studied at eight stratigraphic sections in Sinai, Egypt, which are nearly distributed in a stratigraphic profile from north to south as follows: Al-Hasanah, Sudr Al-Hitan, Wadi Sudr, Al-Thamad, Abu Qada, Wadi Matulla, Wadi Nukhul and Wadi Feiran. This study includes field, litho- and bio-stratigraphic analyses that enabled to delineate several hiatuses which may be due to the occurrence of tectonic activity that may be related to the echo of the Syrian Arc Orogeny at the P/E boundary. Generally, in Egypt the P/E boundary is marked by the occurrence of distinctive five beds, named by El Dababiya Quarry Member. At Wadi Nukhul, Wadi Matulla and Wadi Feiran sections, El Dababiya Quarry Member is well represented and the P/E boundary is conformable and resembles the GSSP section. Although El Dababiya Quarry Member is represented at Al-Hasanah section, the P/E boundary is marked by the occurrence of a minor hiatus at the end of Paleocene. Moreover, at Al Thamad section, El Dababiya Quarry Member is partially represented. On the other hand, at Sudr Al-Hitan, Wadi Sudr and Abu Qada sections, El Dababiya Quarry Member is completely absent due to a major hiatus.

Impact and extinction signatures in complete Cretaceous-Tertiary (K-T) boundary sections

NASA Technical Reports Server (NTRS)

Smit, J.; Groot, H.; Dejonge, R.; Smit, P.

1988-01-01

The Zumaya, Caravaca and Agost sections in Spain, the El Kef section in Tunisia and the Negev (Nahal Avdat) sections in Israel are among the most continuous, expanded and complete K-T boundary sections. The distribution patterns of the planktic faunas were quantitatively analyzed in closely spaced samples across the K-T boundary in these sections, in conjuction with the geochemistry, stable isotopes, mineralogy and magnetostratigraphy. Three hundred foraminiferal specimens were randomly selected and determined. Reliable estimates for the foraminiferal productivity changes across the K-T boundary and for the 1 to 2 Ma interval preceding the K-T boundary were made from the numbers of individuals/gram of sediment corrected for the sedimentation rates (calculated from magnetic reversals and lithology). No gradual or stepwise extinction is seen below the K-T boundary nor any productivity decrease. Stable isotope analyses show a warming just after deposition of the ejecta layer, not cooling as predicted by nuclear winter scenarios, although the duration of such cooling may be too short to be observed even in these complete sections. Low REE values and cpx spherules with quench textures idential to quench-textures in diagenetically altered spherules, strongly indicate an oceanic site of (one of) the impactor(s).

Stratigraphic Units in Las Vegas Valley, Nevada

NASA Astrophysics Data System (ADS)

Donovan, D.

2013-12-01

Using 25 well logs, 15 of which also had accompanying geophysical and aquifer test data were used to describe and establish three alloformations including the Tule Spring and Paradise Valley Alloformations and four aquiformations, the most well defined being, the Las Vegas Springs Aquiformation, in the west central part of the bolson (Donovan, 1996), primarily in Township 20 South, Range 60 East, Mount Diablo Baseline and Meridian (MDBLM), with the stratotypes designated in T20S, R61E S31 MDBLM (36° 9'59.89"N 115°11'26.34"W). The allostratigraphic units were developed using the recommendations in the North American Code of Stratigraphic Nomenclature (NACSN, 1983 and 2005). The hydrostratigraphic units were developed following the recommendations of Seaber (1992). The units constitute the bulk of the upper 500 meter section. Twenty additional wells in the same geographic area, drilled and completed between 1995 and 2005 with detailed geologic and hydrologic information provided confirmation of these units. The proposed stratigraphic units are not part of either, and are located between, the two previously named and non-contiguous formations in the bolson (the Miocene Muddy Creek Formation and the late Pleistocene Las Vegas Formation) (Longwell et al 1965). Las Vegas Valley contains a metropolitan area of approximately two million people. The deeper part of the alluvial basin below 300 ft below ground surface is of interest for supply and storage. The shallower part is of interest for water quality and the interaction between the ground water system and engineered structures.

Examining early-diagenetic processes as a chief sink for carbonate in the aftermath of the Triassic-Jurassic crisis: Hettangian concretions of Muller Canyon, NV, USA

NASA Astrophysics Data System (ADS)

Ritterbush, K. A.; Loyd, S. J.; Corsetti, F. A.; Bottjer, D. J.; Berelson, W.

2015-12-01

Tectonic, climate, and biotic changes across the Triassic-Jurassic transition appear to have resulted in a "carbonate gap" in the rock record of many shallow marine environments. Ecological state changes documented in near-shore settings in both Tethys and Panthassa show an earliest Jurassic switch to sponge-dominated biosiliceous sedimentation regimes. The Sunrise Formation exposed in the Gabbs Valley Range of Nevada (USA) records a peculiar juxtaposition of Hettangian carbonate-rich strata that contain demosponge spicules as the primary bioclast. It is unclear 1) why biocalcifiers were not recorded in higher abundance in this near-shore back-arc basin setting; 2) why carbonates formed following a biosiliceous regime; and 3) what the lithology indicates about post-extinction marine geochemical dynamics. Detailed sedimentological, paleontological, and geochemical analyses were applied to a 20-m thick sequence of limestone and chert in the Muller Canyon area, which is the Auxiliary Stratotype for the Triassic/Jurassic boundary. Concretion anatomy, bioclast microfacies, and oxygen and carbon isotopic signatures all indicate the Hettangian limestones are chiefly diagenetic concretions that all formed very shallowly, some essentially at the sediment-water interface. We infer that local bottom waters and/or pore waters were supersaturated with respect to calcium carbonate and that this contributed to widespread concretion sedimentation independent of biomineralization. Ecological incumbency of the demosponge meadows may have been supported by concurrent augmentation of marine silica concentration and this apparently proved inhospitable to re-colonization of benthic biocalcifying macrofauna. Together the biotic and lithologic consequences of the extinction represent million-year scale ecological restructuring and highlight early diagenetic precipitation as a major sink in long-term regional carbonate cycling. Perhaps the widespread 'carbonate gap' is actually a gap in calcifying macrofauna and the ocean managed to dump alkalinity as diagenetic carbonate.

Geochemistry of K/T boundaries in India and contributions of Deccan volcanism

NASA Technical Reports Server (NTRS)

Bhandari, N.; Gupta, M.; Pandey, J.; Shukla, P. N.

1988-01-01

Three possible Cretaceous/Tertiary (K/T) boundary sections in the Indian subcontinent were studied for their geochemical and fossil characteristics. These include two marine sections of Meghalaya and Zanskar and one continental section of Nagpur. The Um Sohryngkew river section of Meghalaya shows a high iridium, osmium, iron, cobalt, nickel and chromium concentration in a 1.5 cm thick limonitic layer about 30 cm below the planktonic Cretaceous-Palaeocene boundary identified by the characteristic fossils. The Bottaccione and Contessa sections at Gubbio were also analyzed for these elements. The geochemical pattern at the boundary at the Um Sohryngkew river and Gubbio sections are similar but the peak concentrations and the enrichment factors are different. The biological boundary is not as sharp as the geochemical boundary and the extinction appears to be a prolonged process. The Zanskar section shows, in general, similar concentration of the siderophile, lithophile and rare earth elements but no evidence of enrichment of siderophiles has so far been observed. The Takli section is a shallow inter-trappean deposit within the Deccan province, sandwiched between flow 1 and flow 2. The geochemical stratigraphy of the inter-trappeans is presented. The various horizons of ash, clay and marl show concentration of Fe and Co, generally lower than the adjacent basalts. Two horizons of slight enrichment of iridium are found within the ash layers, one near the contact of flow 1 and other near the contact of flow 2, where iridium occurs at 170 and 260 pg/g. These levels are lower by a factor of 30 compared to Ir concentration in the K/T boundary in Meghalaya section. If the enhanced level of some elements in a few horizons of the ash layer are considered as volcanic contribution by some fractionation processes than the only elements for which it occurs are REE, Ir and possibly Cr.

22 CFR 1103.101 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Purpose. 1103.101 Section 1103.101 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.101 Purpose. This...

22 CFR 1103.140 - Employment.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Employment. 1103.140 Section 1103.140 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.140 Employment. No...

22 CFR 1103.111 - Notice.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Notice. 1103.111 Section 1103.111 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.111 Notice. The...

22 CFR 1103.102 - Application.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Application. 1103.102 Section 1103.102 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.102 Application. This...

Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

NASA Technical Reports Server (NTRS)

Dolling, David S.; Barter, John W.

1995-01-01

The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-layer separators' on the same interaction.

Extended period of K/T boundary mass extinction in the marine realm

NASA Technical Reports Server (NTRS)

Keller, G.

1988-01-01

The Cretaceous/Tertiary (K/T) boundary mass extinction has been widely recognized as a nearly instantaneous catastrophy among marine plankton such as foraminifera. However, the suddenness of this extinction event may have been overemphasized because most pelagic K/T boundary sequences are stratigraphically incomplete and generally lack the earliest Tertiary (Zones P0 and P1a) either due to carbonate dissolution and/or non-deposition. Stratigraphically complete sections appear to be restricted to continental shelf regions with high sedimentation rates and deposition well above the CCD. Such sections have been recovered from El Kef, Tunisia (1) and Brazos River, Texas. Quantitative foraminiferal analysis of these sections indicate an extinction pattern beginning below the K/T boundary and ending above the boundary. These data imply that the mass extinction event was not geologically instantaneous, but occurred over an extended period of time. Evidence supporting this conclusion is discussed.

27 CFR 9.52 - Chalk Hill.

Code of Federal Regulations, 2011 CFR

2011-04-01

... the south line of Section 2, Township 8 North (T. 8 N.), Range 9 West (R. 9 W.) at the intersection of... boundary proceeds— (1) Southeasterly along Redwood Highway through Section 11, T. 8 N., R. 9 W., to the... boundary of Section 11, T. 8 N., R. 9 W., to the point of intersection with Starr Road; (3) The southerly...

27 CFR 9.52 - Chalk Hill.

Code of Federal Regulations, 2010 CFR

2010-04-01

... the south line of Section 2, Township 8 North (T. 8 N.), Range 9 West (R. 9 W.) at the intersection of... boundary proceeds— (1) Southeasterly along Redwood Highway through Section 11, T. 8 N., R. 9 W., to the... boundary of Section 11, T. 8 N., R. 9 W., to the point of intersection with Starr Road; (3) The southerly...

27 CFR 9.52 - Chalk Hill.

Code of Federal Regulations, 2014 CFR

2014-04-01

... the south line of Section 2, Township 8 North (T. 8 N.), Range 9 West (R. 9 W.) at the intersection of... boundary proceeds— (1) Southeasterly along Redwood Highway through Section 11, T. 8 N., R. 9 W., to the... boundary of Section 11, T. 8 N., R. 9 W., to the point of intersection with Starr Road; (3) The southerly...

27 CFR 9.52 - Chalk Hill.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the south line of Section 2, Township 8 North (T. 8 N.), Range 9 West (R. 9 W.) at the intersection of... boundary proceeds— (1) Southeasterly along Redwood Highway through Section 11, T. 8 N., R. 9 W., to the... boundary of Section 11, T. 8 N., R. 9 W., to the point of intersection with Starr Road; (3) The southerly...

27 CFR 9.52 - Chalk Hill.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the south line of Section 2, Township 8 North (T. 8 N.), Range 9 West (R. 9 W.) at the intersection of... boundary proceeds— (1) Southeasterly along Redwood Highway through Section 11, T. 8 N., R. 9 W., to the... boundary of Section 11, T. 8 N., R. 9 W., to the point of intersection with Starr Road; (3) The southerly...

27 CFR 9.187 - Covelo.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Highway 162 and the southern boundary of section 25, T22N, R13W (labeled Inspiration Point on the map... southern boundary of section 25, T22N, R13W (labeled Inspiration Point), on the Dos Rios map. [T.D. TTB-42...

27 CFR 9.187 - Covelo.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Highway 162 and the southern boundary of section 25, T22N, R13W (labeled Inspiration Point on the map... southern boundary of section 25, T22N, R13W (labeled Inspiration Point), on the Dos Rios map. [T.D. TTB-42...

Irradiation stratigraphy in the Apollo 16 deep drill section 60002

NASA Technical Reports Server (NTRS)

Blanford, G. E.; Wood, G. C.

1978-01-01

Particle track density frequency distributions, abundance of track rich grains and minimum track densities are reported for the upper 20 cm of the 60002 section of the Apollo 16 deep drill core. The principal stratigraphic feature is a boundary approximately 7 cm from the top of the section. Experimental evidence does not conclusively determine whether this contact is an ancient regolith surface or is simply a depositional boundary. If it is an ancient surface, it has a model exposure age of 3 to 7 million years and a reworking depth of about 0.5 cm. However, because track density frequency distributions indicate the mixing of soils of different maturities, we favor interpreting this contact as a depositional boundary. There may be a second depositional boundary approximately 19 cm below the top of 60002.

22 CFR 1101.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... and Mexico. (d) Commissioner means head of the United States Section, International Boundary and Water Commission, United States and Mexico. (e) Individual means a citizen of the United States or an alien...

22 CFR 1103.170 - Compliance procedures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES... INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.170... Mexico, United States Section, The Commons, Building C, Suite 310, 4171 North Mesa, El Paso, Texas 79902...

22 CFR 1103.130 - General prohibitions against discrimination.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... 1103.130 Section 1103.130 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO...

22 CFR 1103.149 - Program accessibility: Discrimination prohibited.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... 1103.149 Section 1103.149 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO...

22 CFR 1101.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... and Mexico. (d) Commissioner means head of the United States Section, International Boundary and Water Commission, United States and Mexico. (e) Individual means a citizen of the United States or an alien...

22 CFR 1101.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... and Mexico. (d) Commissioner means head of the United States Section, International Boundary and Water Commission, United States and Mexico. (e) Individual means a citizen of the United States or an alien...

22 CFR 1101.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... and Mexico. (d) Commissioner means head of the United States Section, International Boundary and Water Commission, United States and Mexico. (e) Individual means a citizen of the United States or an alien...

Conodonts of the Mississippian/Pennsylvanian boundary interval in Central Iran

NASA Astrophysics Data System (ADS)

Bahrami, A.; Boncheva, I.; Königshof, P.; Yazdi, M.; Ebrahimi Khan-Abadi, A.

2014-10-01

The record of conodonts related to the Mississippian/Pennsylvanian boundary interval was investigated in four sections in Central Iran from two different structural units. Two sections from the Sanandaj-Sirjan trend zone (Asad-abad, and Darchaleh sections) and two from the East-Central Iran Microplate (Shesh-angosht and Kale-Sardar sections) exhibit a nearly complete record previously described across the Mississippian/Pennsylvanian boundary in Iran. The investigated sections can be subdivided in three formations (Ghaleh-, Absheni-, and Zaluda Formation) which belong to the Sardar Group. The mid-Carboniferous boundary was defined by the occurrence of Declinognathus noduliferus s.l.. Bio-event characteristics of the Carboniferous conodont fauna (Mississippian genera Gnathodus and Lochriea have been replaced by Pennsylvanian genera Declinognathus and Idiognathodus) as well as sedimentological changes within overall shallow water deposits were located approximately 33° S of the paleoequator and suggest sea-level changes within the framework of the Late Paleozoic Ice Age (LPIA). Furthermore, a widespread crinoid marker horizon previously described from two localities in Iran can be subdivided into three units of different ages.

Cross-sectional scanning tunneling microscopy of antiphase boundaries in epitaxially grown GaP layers on Si(001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prohl, Christopher; Lenz, Andrea, E-mail: alenz@physik.tu-berlin.de; Döscher, Henning

2016-05-15

In a fundamental cross-sectional scanning tunneling microscopy investigation on epitaxially grown GaP layers on a Si(001) substrate, differently oriented antiphase boundaries are studied. They can be identified by a specific contrast and by surface step edges starting/ending at the position of an antiphase boundary. Moreover, a change in the atomic position of P and Ga atoms along the direction of growth is observed in agreement with the structure model of antiphase boundaries in the GaP lattice. This investigation opens the perspective to reveal the orientation and position of the antiphase boundaries at the atomic scale due to the excellent surfacemore » sensitivity of this method.« less

22 CFR 1103.141-1103.148 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.141-1103.148 Section 1103.141-1103.148 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.151 - Program accessibility: New construction and alterations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... alterations. 1103.151 Section 1103.151 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO...

22 CFR 1103.110 - Self-evaluation.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Self-evaluation. 1103.110 Section 1103.110 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES... INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION § 1103.110 Self...

22 CFR 1103.104-1103.109 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.104-1103.109 Section 1103.104-1103.109 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.131-1103.139 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.131-1103.139 Section 1103.131-1103.139 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.161-1103.169 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.161-1103.169 Section 1103.161-1103.169 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.152-1103.159 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.152-1103.159 Section 1103.152-1103.159 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.112-1103.129 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.112-1103.129 Section 1103.112-1103.129 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

22 CFR 1103.171-1103.999 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true [Reserved] 1103.171-1103.999 Section 1103.171-1103.999 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO... CONDUCTED BY INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...

75 FR 7522 - United States Section; Notice of Availability of the Final Environmental Impact Statement, Flood...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-19

... Final EIS: Biological resources, cultural resources, water resources, land use, socioeconomic resources... INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO United States Section..., International Boundary and Water Commission (USIBWC). ACTION: Notice of Availability of Final Environmental...

23 CFR 1.7 - Urban area boundaries.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Urban area boundaries. 1.7 Section 1.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GENERAL MANAGEMENT AND ADMINISTRATION GENERAL § 1.7 Urban area boundaries. Boundaries of an urban area shall be submitted by the State highway department...

23 CFR 1.7 - Urban area boundaries.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Urban area boundaries. 1.7 Section 1.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GENERAL MANAGEMENT AND ADMINISTRATION GENERAL § 1.7 Urban area boundaries. Boundaries of an urban area shall be submitted by the State highway department...

23 CFR 1.7 - Urban area boundaries.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Urban area boundaries. 1.7 Section 1.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GENERAL MANAGEMENT AND ADMINISTRATION GENERAL § 1.7 Urban area boundaries. Boundaries of an urban area shall be submitted by the State highway department...

34 CFR 222.8 - What action must an applicant take upon a change in its boundary, classification, control...

Code of Federal Regulations, 2010 CFR

2010-07-01

... boundary, classification, control, governing authority, or identity? 222.8 Section 222.8 Education... in its boundary, classification, control, governing authority, or identity? (a) Any applicant that is... its boundaries, classification, control, governing authority, or identity must provide the following...

23 CFR 1.7 - Urban area boundaries.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Urban area boundaries. 1.7 Section 1.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GENERAL MANAGEMENT AND ADMINISTRATION GENERAL § 1.7 Urban area boundaries. Boundaries of an urban area shall be submitted by the State highway department...

34 CFR 222.8 - What action must an applicant take upon a change in its boundary, classification, control...

Code of Federal Regulations, 2013 CFR

2013-07-01

... boundary, classification, control, governing authority, or identity? 222.8 Section 222.8 Education... in its boundary, classification, control, governing authority, or identity? (a) Any applicant that is... its boundaries, classification, control, governing authority, or identity must provide the following...

34 CFR 222.8 - What action must an applicant take upon a change in its boundary, classification, control...

Code of Federal Regulations, 2011 CFR

2011-07-01

... boundary, classification, control, governing authority, or identity? 222.8 Section 222.8 Education... in its boundary, classification, control, governing authority, or identity? (a) Any applicant that is... its boundaries, classification, control, governing authority, or identity must provide the following...

34 CFR 222.8 - What action must an applicant take upon a change in its boundary, classification, control...

Code of Federal Regulations, 2012 CFR

2012-07-01

... boundary, classification, control, governing authority, or identity? 222.8 Section 222.8 Education... in its boundary, classification, control, governing authority, or identity? (a) Any applicant that is... its boundaries, classification, control, governing authority, or identity must provide the following...

34 CFR 222.8 - What action must an applicant take upon a change in its boundary, classification, control...

Code of Federal Regulations, 2014 CFR

2014-07-01

... boundary, classification, control, governing authority, or identity? 222.8 Section 222.8 Education... in its boundary, classification, control, governing authority, or identity? (a) Any applicant that is... its boundaries, classification, control, governing authority, or identity must provide the following...

Development of a Flow Field for Testing a Boundary-Layer-Ingesting Propulsor

NASA Technical Reports Server (NTRS)

Hirt, Stefanie M.; Arend, David J.; Wolter, John D.

2017-01-01

The test section of the 8- by 6-Foot Supersonic Wind Tunnel at NASA Glenn Research Center was modified to produce the test conditions for a boundary-layer-ingesting propulsor. A test was conducted to measure the flow properties in the modified test section before the propulsor was installed. Measured boundary layer and freestream conditions were compared to results from computational fluid dynamics simulations of the external surface for the reference vehicle. Testing showed that the desired freestream conditions and boundary layer thickness could be achieved; however, some non-uniformity of the freestream conditions, particularly the total temperature, were observed.

The Cretaceous-Paleogene transition and Chicxulub impact ejecta in the northwestern Gulf of Mexico: Paleoenvironments, sequence stratigraphic setting and target lithologies

NASA Astrophysics Data System (ADS)

Schulte, Peter

2003-07-01

The Cretaceous-Paleogene (K-P) transition is characterized by a period of mass extinctions, the Chicxulub impact event, sea-level changes, and considerable climate changes (e.g., cooling). The Gulf of Mexico region is a key area for addressing these issues, specifically because of the proximity to the large Chicxulub impact structure in southern Mexico, and because of its shallow shelf areas throughout the Maastrichtian to Danian period. This study presents the results of a multidisciplinary investigation of Chicxulub impact ejecta and marine sediments from the K-P transition in the western Gulf of Mexico. Sedimentological, mineralogical, and geochemical aspects of K-P sections and cores from northeastern Mexico, Texas, and Alabama have been by studied with focus on Chicxulub ejecta, long- or short-term facies change, and sequence stratigraphic setting. CHICXULUB EJECTA: The Chicxulub ejecta (or impact spherule) deposits from northeastern Mexico and Texas revealed an unexpected complex and localized ejecta composition. Fe-Mg-rich chlorite- as well as Si-Al-K-rich glass-spherules are the predominant silicic ejecta components in northeastern Mexico, whereas in Texas, spherules of Mg-rich smectite compositions were encountered. Spherules contain Fe-Ti-K-rich schlieren, Fe-Mg-rich globules, and rare µm-sized metallic and sulfidic Ni-Co-(Ir-?) rich inclusions. This composition provides evidence for a distinct range of target rocks of mafic to intermediate composition, presumably situated in the northwestern sector of the Chicxulub impact structure, in addition to the possibility of contamination by meteoritic material. The absence of spinels and the ubiquitous presence of hematite and goethite points to high oxygen fugacity during the impact process. Besides these silicic phases, the most prominent ejecta component is carbonate.! Carbonate is found in ejecta deposits as unshocked clasts, accretionary lapilli-like grains, melt globules (often with quenching textures), and as microspar, suggesting that this area received ejecta mainly from shallow, carbonate-rich lithologies at the impact site on the Yucatán carbonate platform. Albeit the ejecta spherules are mostly altered to clay minerals and iron oxides, the microfacies and internal textures of the ejecta particles show a variety of distinct features, including welding and fusing of components and evidence for liquid immiscibility between silicic-silicic and carbonate-silicic melts. No evidence for binary mixing of ejecta phases was found. Therefore, it is assumed that ejecta in northeastern Mexico derived from less energetic parts of the ejecta curtain. The welding features of ejecta particles suggest an initial ground surge-like ejecta-dispersion mode. The specific morphological features and the compositional range of Chicxulub ejecta, as well as the results of petrological and rock magnetic characteristics reveal similarities to Chicxulub ejecta from K-P sections in the Gulf of Mexico area, the Caribbean, the Atlantic, the Pacific, and Northern America (Western Interior). In addition, Mg-rich smectite, K-feldspar, and iron oxide-rich microspherules are characteristic for the K-P boundary clay layer in sections from the Atlantic and Tethyan realm, suggestive of a relationship between the Chicxulub impact event and the basal K-P boundary clay layer. EJECTA DEPOSITS: The Chicxulub ejecta deposits are commonly associated with an event deposit that shows a complex succession of deposition from high-energetic (channelized) debris flows or turbidity currents derived from multiple source areas, followed by a period of decreasing current energy and intermittent periods of reworking. The uppermost parts of these deposits are often bioturbated, pointing to longer periods of deposition, as also sustained by the complex internal subdivision of the K-P event deposits. In northeastern Mexico, Chicxulub ejecta is also locally embedded within latest Maastrichtian marls, though common soft-sediment deformation opposes a clear age assignation of these deposits. However, individual spherule layers in the slumped and in the channelized spherule deposits are of similar petrological, mineralogical, and geochemical composition with no size-sorting and abrasion of ejecta, hence pointing to an origin from a single impact event (Chicxulub) and providing no evidence for extended periods between reworking of individual spherule layers. In the Brazos core from Texas, a m-thick shale interval, almost devoid of micro- and macrofossils and therefore of unclear stratigraphic age, is sandwiched between Chicxulub impact ejecta and the first appearance of Paleocene microfossils, indicating a period (of enhanced reworking?) between these two events. However, no mm-thick ferruginous layer with Ni-rich spinels, smectite spherules, and shocked quartz that defines the K-P boundary in the Global Stratotype Section and Point (GSSP) at El Kef, Tunisia, and elsewhere has been observed in any of the sections and cores studied. Therefore, an unequivocal positioning of the K-P boundary is difficult for the northwestern Gulf of Mexico region. PALEOCLIMATE RECORD: The long-term record of clay mineral species during the K-P transition of northeastern Mexico, Texas, and Alabama shows remarkably localized compositional patterns, indicating local sediment influx from topographically, petrologically, and probably climatically distinct source regions. Chlorite-illite-dominated clay assemblages in northwestern Mexico indicate mafic source rocks, predominance of physical weathering, and cooler climates, probably associated with the uplift of the Sierra Madre Oriental, whereas a smectite-dominated clay assemblage in Texas indicates semiarid-humid climates. In central Alabama, a distinct trend from tropically humid and warm climates to more seasonal and drier climate that already started in the late Maastrichtian was inferred from a prominent change of a kaolinite- to a smectite-dominated clay mineral assemblage. Hence, no unique climate conditions and distinct climate trends can be inferred for the northwestern Gulf of Mexico area from the data provided by this study. SEQUENCE STRATIGRAPHY: The sequence stratigraphic setting of the Maastrichtian to Danian strata in northeastern Mexico, Texas, and Alabama is also quite complex. The deep-water marls in northeastern Mexico were not amenable to a clear sequence stratigraphic subdivision, though the similar mineralogical (and geochemical) composition of the Maastrichtian to Danian marls provided no evidence for a distinct major facies change during this interval. In Texas, no facies change was observed for the (highstand) shale interval that includes the event bed, though a gradual sea-level lowering took place upon the appearance of the earliest Paleocene microfossils. A sequence boundary is present in the earliest Danian and overlain by transgressive systems tract. In central Alabama, a pronounced sea-level shallowing was recognized during a highstand systems tract in the late Maastrichtian, topped by a sequence boundary and subsequent (strongly) rising sea level throughout the latest Maastrichtian and the early Danian. Rapid and intense water-depth fluctuations are inferred from middle Danian carbonate-rich strata concomitant to a change from a mixed siliciclastic-carbonate depositional system to a more stable carbonate platform in central Alabama during this period. In summary, no universal pattern of facies and related sea-level changes was obtained from the northwestern Gulf of Mexico area, and particularly, no evidence for adverse an- or dysoxic sedimentary conditions were observed for the Maastrichtian to Danian interval governed by this study.

49 CFR 372.201 - Albany, NY.

Code of Federal Regulations, 2010 CFR

2010-10-01

... section, thence along the western and northern boundary of Cohoes to the Mohawk River thence along such river to the northern boundary of the Town of Waterford thence along the northern and eastern boundaries of the Town of Waterford to the northern boundary of the City of Troy (all of which city is included...

A boundary integral method for numerical computation of radar cross section of 3D targets using hybrid BEM/FEM with edge elements

NASA Astrophysics Data System (ADS)

Dodig, H.

2017-11-01

This contribution presents the boundary integral formulation for numerical computation of time-harmonic radar cross section for 3D targets. Method relies on hybrid edge element BEM/FEM to compute near field edge element coefficients that are associated with near electric and magnetic fields at the boundary of the computational domain. Special boundary integral formulation is presented that computes radar cross section directly from these edge element coefficients. Consequently, there is no need for near-to-far field transformation (NTFFT) which is common step in RCS computations. By the end of the paper it is demonstrated that the formulation yields accurate results for canonical models such as spheres, cubes, cones and pyramids. Method has demonstrated accuracy even in the case of dielectrically coated PEC sphere at interior resonance frequency which is common problem for computational electromagnetic codes.

A sharp and flat section of the core-mantle boundary

USGS Publications Warehouse

Vidale, J.E.; Benz, H.M.

1992-01-01

THE transition zone between the Earth's core and mantle plays an important role as a boundary layer for mantle and core convection1. This zone conducts a large amount of heat from the core to the mantle, and contains at least one thermal boundary layer2,3; the proximity of reactive silicates and molten iron leads to the possibility of zones of intermediate composition4. Here we investigate one region of the core-mantle boundary using seismic waves that are converted from shear to compressional waves by reflection at the boundary. The use of this phase (known as ScP), the large number of receiving stations, and the large aperture of our array all provide higher resolution than has previously been possible5-7. For the 350-km-long section of the core-mantle boundary under the northeast Pacific sampled by the reflections, the local boundary topography has an amplitude of less than 500 m, no sharp radial gradients exist in the 400 km above the boundary, and the mantle-lo-core transition occurs over less than 1 km. The simplicity of the structure near and above the core-mantle boundary argues against chemical heterogeneity at the base of the mantle in this location.

Section-constrained local geological interface dynamic updating method based on the HRBF surface

NASA Astrophysics Data System (ADS)

Guo, Jiateng; Wu, Lixin; Zhou, Wenhui; Li, Chaoling; Li, Fengdan

2018-02-01

Boundaries, attitudes and sections are the most common data acquired from regional field geological surveys, and they are used for three-dimensional (3D) geological modelling. However, constructing topologically consistent 3D geological models from rapid and automatic regional modelling with convenient local modifications remains unresolved. In previous works, the Hermite radial basis function (HRBF) surface was introduced for the simulation of geological interfaces from geological boundaries and attitudes, which allows 3D geological models to be automatically extracted from the modelling area by the interfaces. However, the reasonability and accuracy of non-supervised subsurface modelling is limited without further modifications generated through explanations and analyses performed by geology experts. In this paper, we provide flexible and convenient manual interactive manipulation tools for geologists to sketch constraint lines, and these tools may help geologists transform and apply their expert knowledge to the models. In the modified modelling workflow, the geological sections were treated as auxiliary constraints to construct more reasonable 3D geological models. The geometric characteristics of section lines were abstracted to coordinates and normal vectors, and along with the transformed coordinates and vectors from boundaries and attitudes, these characteristics were adopted to co-calculate the implicit geological surface function parameters of the HRBF equations and form constrained geological interfaces from topographic (boundaries and attitudes) and subsurface data (sketched sections). Based on this new modelling method, a prototype system was developed, in which the section lines could be imported from databases or interactively sketched, and the models could be immediately updated after the new constraints were added. Experimental comparisons showed that all boundary, attitude and section data are well represented in the constrained models, which are consistent with expert explanations and help improve the quality of the models.

An evaluation of four single element airfoil analytic methods

NASA Technical Reports Server (NTRS)

Freuler, R. J.; Gregorek, G. M.

1979-01-01

A comparison of four computer codes for the analysis of two-dimensional single element airfoil sections is presented for three classes of section geometries. Two of the computer codes utilize vortex singularities methods to obtain the potential flow solution. The other two codes solve the full inviscid potential flow equation using finite differencing techniques, allowing results to be obtained for transonic flow about an airfoil including weak shocks. Each program incorporates boundary layer routines for computing the boundary layer displacement thickness and boundary layer effects on aerodynamic coefficients. Computational results are given for a symmetrical section represented by an NACA 0012 profile, a conventional section illustrated by an NACA 65A413 profile, and a supercritical type section for general aviation applications typified by a NASA LS(1)-0413 section. The four codes are compared and contrasted in the areas of method of approach, range of applicability, agreement among each other and with experiment, individual advantages and disadvantages, computer run times and memory requirements, and operational idiosyncrasies.

47 CFR 22.912 - Service area boundary extensions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Service area boundary extensions. 22.912 Section 22.912 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.912 Service area boundary extensions. This...

47 CFR 22.912 - Service area boundary extensions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Service area boundary extensions. 22.912 Section 22.912 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.912 Service area boundary extensions. This...

47 CFR 22.912 - Service area boundary extensions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Service area boundary extensions. 22.912 Section 22.912 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.912 Service area boundary extensions. This...

27 CFR 9.192 - Wahluke Slope.

Code of Federal Regulations, 2011 CFR

2011-04-01

... boundary line of section 15, which forms a portion of the boundary line of the Hanford Site, T15N/R26E, Wahatis Peak map; then (4) Proceed generally southwest along the Hanford Site boundary in a series of 90... Bridge map, and continue onto the Priest Rapids NE map to the intersection of the Hanford Site boundary...

27 CFR 9.192 - Wahluke Slope.

Code of Federal Regulations, 2010 CFR

2010-04-01

... boundary line of section 15, which forms a portion of the boundary line of the Hanford Site, T15N/R26E, Wahatis Peak map; then (4) Proceed generally southwest along the Hanford Site boundary in a series of 90... Bridge map, and continue onto the Priest Rapids NE map to the intersection of the Hanford Site boundary...

27 CFR 9.192 - Wahluke Slope.

Code of Federal Regulations, 2012 CFR

2012-04-01

... boundary line of section 15, which forms a portion of the boundary line of the Hanford Site, T15N/R26E, Wahatis Peak map; then (4) Proceed generally southwest along the Hanford Site boundary in a series of 90... Bridge map, and continue onto the Priest Rapids NE map to the intersection of the Hanford Site boundary...

27 CFR 9.192 - Wahluke Slope.

Code of Federal Regulations, 2013 CFR

2013-04-01

... boundary line of section 15, which forms a portion of the boundary line of the Hanford Site, T15N/R26E, Wahatis Peak map; then (4) Proceed generally southwest along the Hanford Site boundary in a series of 90... Bridge map, and continue onto the Priest Rapids NE map to the intersection of the Hanford Site boundary...

27 CFR 9.192 - Wahluke Slope.

Code of Federal Regulations, 2014 CFR

2014-04-01

... boundary line of section 15, which forms a portion of the boundary line of the Hanford Site, T15N/R26E, Wahatis Peak map; then (4) Proceed generally southwest along the Hanford Site boundary in a series of 90... Bridge map, and continue onto the Priest Rapids NE map to the intersection of the Hanford Site boundary...

36 CFR 293.16 - Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest, Minnesota. 293.16 Section 293.16... Forest, Minnesota. (a) Motorboat use. (1) For purposes of this section, motorboats permitted to operate...

36 CFR 293.16 - Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest, Minnesota. 293.16 Section 293.16... Forest, Minnesota. (a) Motorboat use. (1) For purposes of this section, motorboats permitted to operate...

36 CFR 293.16 - Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Special provisions governing the Boundary Waters Canoe Area Wilderness, Superior National Forest, Minnesota. 293.16 Section 293.16... Forest, Minnesota. (a) Motorboat use. (1) For purposes of this section, motorboats permitted to operate...

75 FR 21659 - Notice of Availability of a Draft Environmental Assessment and Finding of No Significant Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

... INTERNATIONAL BOUNDARY AND WATER COMMIISSION UNITED STATES AND MEXICO; UNITED STATES SECTION... States Section, International Boundary and Water Commission, United States and Mexico (USIBWC). ACTION... Water Commission; 4171 N. Mesa, C-100; El Paso, Texas 79902. Telephone: (915) 832-4707; e-mail: lisa...

A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy

NASA Astrophysics Data System (ADS)

Rasmussen, Sune O.; Bigler, Matthias; Blockley, Simon P.; Blunier, Thomas; Buchardt, Susanne L.; Clausen, Henrik B.; Cvijanovic, Ivana; Dahl-Jensen, Dorthe; Johnsen, Sigfus J.; Fischer, Hubertus; Gkinis, Vasileios; Guillevic, Myriam; Hoek, Wim Z.; Lowe, J. John; Pedro, Joel B.; Popp, Trevor; Seierstad, Inger K.; Steffensen, Jørgen Peder; Svensson, Anders M.; Vallelonga, Paul; Vinther, Bo M.; Walker, Mike J. C.; Wheatley, Joe J.; Winstrup, Mai

2014-12-01

Due to their outstanding resolution and well-constrained chronologies, Greenland ice-core records provide a master record of past climatic changes throughout the Last Interglacial-Glacial cycle in the North Atlantic region. As part of the INTIMATE (INTegration of Ice-core, MArine and TErrestrial records) project, protocols have been proposed to ensure consistent and robust correlation between different records of past climate. A key element of these protocols has been the formal definition and ordinal numbering of the sequence of Greenland Stadials (GS) and Greenland Interstadials (GI) within the most recent glacial period. The GS and GI periods are the Greenland expressions of the characteristic Dansgaard-Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. We present here a more detailed and extended GS/GI template for the whole of the Last Glacial period. It is based on a synchronization of the NGRIP, GRIP, and GISP2 ice-core records that allows the parallel analysis of all three records on a common time scale. The boundaries of the GS and GI periods are defined based on a combination of stable-oxygen isotope ratios of the ice (δ18O, reflecting mainly local temperature) and calcium ion concentrations (reflecting mainly atmospheric dust loading) measured in the ice. The data not only resolve the well-known sequence of Dansgaard-Oeschger events that were first defined and numbered in the ice-core records more than two decades ago, but also better resolve a number of short-lived climatic oscillations, some defined here for the first time. Using this revised scheme, we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the Last Glacial period that are represented in the Greenland ice records. The final product constitutes an extended and better resolved Greenland stratotype sequence, against which other proxy records can be compared and correlated. It also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations.

The structure of a turbulent flow in a channel of complex shape

USGS Publications Warehouse

Tracy, Hubert Jerome

1976-01-01

Measurements of the Reynolds stresses and the mean motion pattern were made in a uniform turbulent motion in a conduit consisting of a large, nearly square section joined by a smaller rectangular section. The results indicate that the boundary shearing stress is nearly constant over large segments of the boundaries. The magnitudes of the lateral and the vertical components of turbulence are not the same near a boundary and the component normal to the boundary is smaller than the component parallel to the boundary. The difference in the two components in the corner regions of the channel produces secondary mean motions in the plane of the channel section. The strength of the motion depends upon the angle subtended by the corner. A principal function of the secondary motions is to transfer momentum into the corner regions and, elsewhere, to compensate for the excess force due to the shear gradients. In the absence of the secondary motions, the fluid must stagnate and separate from the boundaries in certain regions and be greatly accelerated in others. The secondary motions are conventionally described in terms of symmetrical rotations in cells bounded by the corner bisectors. The measured motion pattern is at variance with this view, unless the symmetry is confined to a very local region. (Woodard-USGS)

Magnetostratigraphic correlations of Permian-Triassic marine-to-terrestrial sections from China

USGS Publications Warehouse

Glen, J.M.G.; Nomade, S.; Lyons, J.J.; Metcalfe, I.; Mundil, R.; Renne, P.R.

2009-01-01

We have studied three Permian–Triassic (PT) localities from China as part of a combined magnetostratigraphic, 40Ar/39Ar and U–Pb radioisotopic, and biostratigraphic study aimed at resolving the temporal relations between terrestrial and marine records across the Permo-Triassic boundary, as well as the rate of the biotic recovery in the Early Triassic. The studied sections from Shangsi (Sichuan Province), Langdai (Guihzou Province), and the Junggar basin (Xinjiang Province), span marine, paralic, and terrestrial PT environments, respectively. Each of these sections was logged in detail in order to place geochronologic, paleomagnetic, geochemical, conodont and palynologic samples within a common stratigraphic context. Here we present rock-magnetic, paleomagnetic and magnetostratigraphic results from the three localities.At Shangsi, northern Sichuan Province, we sampled three sections spanning Permo-Triassic marine carbonates. Magnetostratigraphic results from the three sections indicate that the composite section contains at least eight polarity chrons and that the PT boundary occurs within a normal polarity chron a short distance above the mass extinction level and a reversed-to-normal (R-N) polarity reversal. Furthermore, the onset of the Illawarra mixed interval lies below the sampled section indicating that the uppermost Permian Changhsingian and at least part of the Wuchiapingian stages postdate the end of the Kiaman Permo-Carboniferous Reversed Superchron.At Langdai, Guizhou Province, we studied magnetostratigraphy of PT paralic mudstone and carbonate sediments in two sections. The composite section spans an R-N polarity sequence. Section-mean directions pass a fold test at the 95% confidence level, and the section-mean poles are close to the mean PT pole for the South China block. Based on biostratigraphic constraints, the R-N transition recorded at Langdai is consistent with that at Shangsi and demonstrates that the PT boundary occurred within a normal polarity chron a short distance above the mass extinction level.In the southern Junggar basin, Xinjiang Province, in northwest China, we determined the magnetostratigraphy of three sections of a terrestrial sequence. Normal and reversed polarity directions are roughly antipodal, and magnetostratigraphies from the three sections are highly consistent. Combined bio- and magneto-stratigraphy used to correlate this sequence to other PT sequences suggests that the previously-proposed biostratigraphic PT boundary in the Junggar sections was most likely misplaced by earlier workers suggesting that further work is necessary to confidently place the PT boundary there.

K-T impact(s): Continental, oceanic or both

NASA Technical Reports Server (NTRS)

Sharpton, V. L.; Schuraytz, B. C.; Murali, A. V.; Ryder, G.; Burke, K.

1988-01-01

Although geochemical and mineralogical evidence indicate that a major accretionary event occurred at the K-T boundary, no impact crater of suitable size and age was recognized. The 35 km Manson Structure, Iowa, was suggested recently as a possibility and Ar-40/Ar-39 determinations indicate that its formation age is indistinguishable from that of the K-T boundary. In order to test a possible association between Manson and the K-T boundary clay, the geochemistry and mineralogy of the K-T boundary clays at the Scollard Canyon section, Alberta and the Starkville South section, Colorado are compared with three dominant lithologies affected by the Manson impact: Proterozoic red clastics, underlying late-state granites, and gneisses. The chemical and mineralogical makeup of the Scollard Canyon boundary clay and its clastic constituents are presented, commenting on the implications for impact models. An impact into crystalline material of continental affinity appears to be required to explain the mineralogy and chemistry of the Scollard Canyon (and other Western N. American K-T sections). The low REE abundances of some K-T boundary layers are unusual but perhaps attempts should be made to understand the contributions of individual crustal components (e.g., carbonates, arkoses) as well as the potential for alteration involving these and other elements during and after impact-induced vaporization, before mantle excavation is invoked. If further studies confirm the results of published studies of marine boundary clays that indicate an oceanic target, attention must be paid to the possibility that multiple impacts occurred at the K-T boundary - one or more on the continents and one or more in the ocean.

10 CFR 300.4 - Selecting organizational boundaries.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Selecting organizational boundaries. 300.4 Section 300.4 Energy DEPARTMENT OF ENERGY CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.4 Selecting organizational boundaries. (a) Each reporting entity must disclose in its entity...

10 CFR 300.4 - Selecting organizational boundaries.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Selecting organizational boundaries. 300.4 Section 300.4 Energy DEPARTMENT OF ENERGY CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.4 Selecting organizational boundaries. (a) Each reporting entity must disclose in its entity...

10 CFR 300.4 - Selecting organizational boundaries.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Selecting organizational boundaries. 300.4 Section 300.4 Energy DEPARTMENT OF ENERGY CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.4 Selecting organizational boundaries. (a) Each reporting entity must disclose in its entity...

10 CFR 300.4 - Selecting organizational boundaries.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Selecting organizational boundaries. 300.4 Section 300.4 Energy DEPARTMENT OF ENERGY CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.4 Selecting organizational boundaries. (a) Each reporting entity must disclose in its entity...

10 CFR 300.4 - Selecting organizational boundaries.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Selecting organizational boundaries. 300.4 Section 300.4 Energy DEPARTMENT OF ENERGY CLIMATE CHANGE VOLUNTARY GREENHOUSE GAS REPORTING PROGRAM: GENERAL GUIDELINES § 300.4 Selecting organizational boundaries. (a) Each reporting entity must disclose in its entity...

49 CFR 71.1 - Limits defined; exceptions authorized for certain rail operating purposes only.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Transportation STANDARD TIME ZONE BOUNDARIES § 71.1 Limits defined; exceptions authorized for certain rail... zones established by section 1 of the Standard Time Act, as amended by section 4 of the Uniform Time Act... carriers, whose operations cross the time zone boundaries prescribed by this part, authorizing them to...

Macrofossil extinction patterns at Bay of Biscay Cretaceous-Tertiary boundary sections

NASA Technical Reports Server (NTRS)

Ward, Peter D.; Macleod, Kenneth

1988-01-01

Researchers examined several K-T boundary cores at Deep Sea Drilling Project (DSDP) core repositories to document biostratigraphic ranges of inoceramid shell fragments and prisms. As in land-based sections, prisms in the deep sea cores disappear well before the K-T boundary. Ammonites show a very different extinction pattern than do the inoceramids. A minimum of seven ammonite species have been collected from the last meter of Cretaceous strata in the Bay of Biscay basin. In three of the sections there is no marked drop in either species numbers or abundance prior to the K-T boundary Cretaceous strata; at the Zumaya section, however, both species richness and abundance drop in the last 20 m of the Cretaceous, with only a single ammonite specimen recovered to date from the uppermost 12 m of Cretaceous strata in this section. Researchers conclude that inoceramid bivalves and ammonites showed two different times and patterns of extinction, at least in the Bay of Biscay region. The inoceramids disappeared gradually during the Early Maestrichtian, and survived only into the earliest Late Maestrichtian. Ammonites, on the other hand, maintained relatively high species richness throughout the Maestrichtian, and then disappeared suddenly, either coincident with, or immediately before the microfossil extinction event marking the very end of the Cretaceous.

Natural laminar flow and airplane stability and control

NASA Technical Reports Server (NTRS)

Vandam, Cornelis P.

1986-01-01

Location and mode of transition from laminar to turbulent boundary layer flow have a dominant effect on the aerodynamic characteristics of an airfoil section. The influences of these parameters on the sectional lift and drag characteristics of three airfoils are examined. Both analytical and experimental results demonstrate that when the boundary layer transitions near the leading edge as a result of surface roughness, extensive trailing-edge separation of the turbulent boundary layer may occur. If the airfoil has a relatively sharp leading-edge, leading-edge stall due to laminar separation can occur after the leading-edge suction peak is formed. These two-dimensional results are used to examine the effects of boundary layer transition behavior on airplane longitudinal and lateral-directional stability and control.

Experimental Research on Boundary Shear Stress in Typical Meandering Channel

NASA Astrophysics Data System (ADS)

Chen, Kai-hua; Xia, Yun-feng; Zhang, Shi-zhao; Wen, Yun-cheng; Xu, Hua

2018-06-01

A novel instrument named Micro-Electro-Mechanical System (MEMS) flexible hot-film shear stress sensor was used to study the boundary shear stress distribution in the generalized natural meandering open channel, and the mean sidewall shear stress distribution along the meandering channel, and the lateral boundary shear stress distribution in the typical cross-section of the meandering channel was analysed. Based on the measurement of the boundary shear stress, a semi-empirical semi-theoretical computing approach of the boundary shear stress was derived including the effects of the secondary flow, sidewall roughness factor, eddy viscosity and the additional Reynolds stress, and more importantly, for the first time, it combined the effects of the cross-section central angle and the Reynolds number into the expressions. Afterwards, a comparison between the previous research and this study was developed. Following the result, we found that the semi-empirical semi-theoretical boundary shear stress distribution algorithm can predict the boundary shear stress distribution precisely. Finally, a single factor analysis was conducted on the relationship between the average sidewall shear stress on the convex and concave bank and the flow rate, water depth, slope ratio, or the cross-section central angle of the open channel bend. The functional relationship with each of the above factors was established, and then the distance from the location of the extreme sidewall shear stress to the bottom of the open channel was deduced based on the statistical theory.

Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

NASA Astrophysics Data System (ADS)

Hamers, M. F.; Pennock, G. M.; Drury, M. R.

2017-04-01

The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

75 FR 5173 - Public Notice for Waiver of Aeronautical Land-Use Assurance; Indianapolis International Airport...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-01

... seconds East 1,328.93 feet along the south line of said quarter section to the prolonged west boundary of... the west boundary of said I-465 meets the north boundary of Hanna Avenue; thence South 90 degrees 00... line to the west boundary of said I-465; thence South 2 degrees 09 minutes 28 seconds East 390.53 feet...

Effect of Annealing Treatment on Σ3-Type CSL Boundaries and Its Interactions in 304HCu Grade Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Dash, Manmath Kumar; Mythili, R.; Dasgupta, Arup; Saroja, S.

2018-04-01

This paper presents the results of a study on grain boundary characteristics in cold deformed and annealed 304HCu grade austenitic stainless steel (SS 304HCu) using electron backscatter diffraction. The microstructure exhibited an increasing fraction of Σ1 to 29 coincidence site lattice boundaries with annealing temperature, resulting up to 60 pct at 1573 K with 92 pct contribution from Σ3-type twin boundary. However, the twin boundary interaction at the triple points with a network of Σ3-Σ3-Σ9 was found to decrease from 4 to 0.5 pct with annealing temperature. To understand the resultant boundary advancement of the Σ3 n (n = 1, 2, 3) boundaries, their migration was traced in the annealed specimen. However, in the specimen with extended annealing Σ3 boundary fraction was found to be higher with a concomitant decrease in the boundary fraction generated by the Σ3 interactions. In this study, a procedure to analyze the coherency of Σ3 boundaries and its interfaces that form due to Σ3 interactions has been evolved based on single-section analysis using the pole concentration across the grains. Further, a crystallographic description of the two planes meeting at the interface of Σ3-type boundary has been provided by adopting serial sectioning methods, which help to understand the morphological changes. The quantitative deviation from exact coherent Σ3 has been estimated to be within 6 deg in this study.

Effect of Annealing Treatment on Σ3-Type CSL Boundaries and Its Interactions in 304HCu Grade Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Dash, Manmath Kumar; Mythili, R.; Dasgupta, Arup; Saroja, S.

2018-07-01

This paper presents the results of a study on grain boundary characteristics in cold deformed and annealed 304HCu grade austenitic stainless steel (SS 304HCu) using electron backscatter diffraction. The microstructure exhibited an increasing fraction of Σ1 to 29 coincidence site lattice boundaries with annealing temperature, resulting up to 60 pct at 1573 K with 92 pct contribution from Σ3-type twin boundary. However, the twin boundary interaction at the triple points with a network of Σ3-Σ3-Σ9 was found to decrease from 4 to 0.5 pct with annealing temperature. To understand the resultant boundary advancement of the Σ3 n ( n = 1, 2, 3) boundaries, their migration was traced in the annealed specimen. However, in the specimen with extended annealing Σ3 boundary fraction was found to be higher with a concomitant decrease in the boundary fraction generated by the Σ3 interactions. In this study, a procedure to analyze the coherency of Σ3 boundaries and its interfaces that form due to Σ3 interactions has been evolved based on single-section analysis using the pole concentration across the grains. Further, a crystallographic description of the two planes meeting at the interface of Σ3-type boundary has been provided by adopting serial sectioning methods, which help to understand the morphological changes. The quantitative deviation from exact coherent Σ3 has been estimated to be within 6 deg in this study.

29 CFR 776.13 - Commerce crossing international boundaries.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 3 2014-07-01 2014-07-01 false Commerce crossing international boundaries. 776.13 Section... Engaging âin Commerceâ § 776.13 Commerce crossing international boundaries. Under the Act, as amended, an employee engaged in “trade commerce, transportation, transmission, or communication” between any State and...

29 CFR 776.13 - Commerce crossing international boundaries.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 3 2012-07-01 2012-07-01 false Commerce crossing international boundaries. 776.13 Section... Engaging âin Commerceâ § 776.13 Commerce crossing international boundaries. Under the Act, as amended, an employee engaged in “trade commerce, transportation, transmission, or communication” between any State and...

29 CFR 776.13 - Commerce crossing international boundaries.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 3 2010-07-01 2010-07-01 false Commerce crossing international boundaries. 776.13 Section... Engaging âin Commerceâ § 776.13 Commerce crossing international boundaries. Under the Act, as amended, an employee engaged in “trade commerce, transportation, transmission, or communication” between any State and...

29 CFR 776.13 - Commerce crossing international boundaries.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 3 2011-07-01 2011-07-01 false Commerce crossing international boundaries. 776.13 Section... Engaging âin Commerceâ § 776.13 Commerce crossing international boundaries. Under the Act, as amended, an employee engaged in “trade commerce, transportation, transmission, or communication” between any State and...

29 CFR 776.13 - Commerce crossing international boundaries.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 3 2013-07-01 2013-07-01 false Commerce crossing international boundaries. 776.13 Section... Engaging âin Commerceâ § 776.13 Commerce crossing international boundaries. Under the Act, as amended, an employee engaged in “trade commerce, transportation, transmission, or communication” between any State and...

46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

Code of Federal Regulations, 2013 CFR

2013-10-01

... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively. ...

46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

Code of Federal Regulations, 2014 CFR

2014-10-01

... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively. ...

46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

Code of Federal Regulations, 2011 CFR

2011-10-01

... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively. ...

46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

Code of Federal Regulations, 2012 CFR

2012-10-01

... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively. ...

46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

Code of Federal Regulations, 2010 CFR

2010-10-01

... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively. ...

23 CFR 470.105 - Urban area boundaries and highway functional classification.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Urban area boundaries and highway functional classification. 470.105 Section 470.105 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH HIGHWAY SYSTEMS Federal-aid Highway Systems § 470.105 Urban area boundaries and...

23 CFR 470.105 - Urban area boundaries and highway functional classification.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Urban area boundaries and highway functional classification. 470.105 Section 470.105 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH HIGHWAY SYSTEMS Federal-aid Highway Systems § 470.105 Urban area boundaries and...

23 CFR 470.105 - Urban area boundaries and highway functional classification.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Urban area boundaries and highway functional classification. 470.105 Section 470.105 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH HIGHWAY SYSTEMS Federal-aid Highway Systems § 470.105 Urban area boundaries and...

23 CFR 470.105 - Urban area boundaries and highway functional classification.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 23 Highways 1 2012-04-01 2012-04-01 false Urban area boundaries and highway functional classification. 470.105 Section 470.105 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH HIGHWAY SYSTEMS Federal-aid Highway Systems § 470.105 Urban area boundaries and...

27 CFR 9.204 - Tracy Hills.

Code of Federal Regulations, 2010 CFR

2010-04-01

... and Lammers Ferry Road, along the western boundary line of section 6, T3S/R5E. From the beginning... Western Pacific Railway line along the southern boundary line of section 6, T3S/R5E (Tracy map); then (2) Proceed 5.6 miles straight east along the Western Pacific Railway line and then along Linne Road to the...

Position of the Upper Devonian Frasnian--Famennian boundary in the central Appalachians

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossbach, T.J.

Biostratigraphic analysis of eight Upper Devonian sections in VA and WV reveals that the section at Huttonsville, Randolph County, WV, is a key locality for determining the Frasnian-Famennian boundary. The Foreknobs Formation at Huttonsville indicates a higher stratigraphic placement of the Frasnian-Famennian boundary than has been generally assumed. Conodonts are not known within that section, so placement of the boundary uses the last occurrence of tentaculitids and the last and first occurrences of several species of brachiopods. It is believed that the Frasnian-Famennian boundary can be identified independently of the atrypoid brachiopods. Stratigraphic ranges of the cricoconarid Tentaculites discusses andmore » the brachiopod Tropidoleptus carinatus, both considered Frasnian marker fossils, indicate that the Frasnian extends well into the Red Lick Member of the Foreknobs Formation at Huttonsville, with T. carinatus occurring up to 70% of the stratigraphic thickness of the Red Lick. The Famennian marker fossils A. angelica and C. sulcifer are both found at Huttonsville above the last recorded occurrence of all the Frasnian marker fossils. To the northeast of Huttonsville the Frasnian-Famennian series boundary has been placed by other workers within or at the top of the Pound Member of the Foreknobs Formation. This discrepancy implies that either the Pound Member is diachronous or that to the northeast paleoecologic factors caused local disappearances of critical fossils before their extinction at Huttonsville.« less

Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition.

PubMed

Dong, Yajie; Wu, Naiqin; Li, Fengjiang; Huang, Linpei; Wen, Wenwen

2015-01-01

The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS) has previously been assumed to be synchronous with the Marine Isotope Stage (MIS) 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP). However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR) protocol to the 45-63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL) samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3-4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast.

Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition

PubMed Central

Dong, Yajie; Wu, Naiqin; Li, Fengjiang; Huang, Linpei; Wen, Wenwen

2015-01-01

The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS) has previously been assumed to be synchronous with the Marine Isotope Stage (MIS) 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP). However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR) protocol to the 45–63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL) samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3–4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast. PMID:26186443

The Permian-Triassic boundary & mass extinction in China

USGS Publications Warehouse

Metcalfe, I.; Nicoll, R.S.; Mundil, R.; Foster, C.; Glen, J.; Lyons, J.; Xiaofeng, W.; Cheng-Yuan, W.; Renne, P.R.; Black, L.; Xun, Q.; Xiaodong, M.

2001-01-01

The first appearance of Hindeodus parvus (Kozur & Pjatakova) at the Permian-Triassic (P-T) GSSP level (base of Bed 27c) at Meishan is here confirmed. Hindeodus changxingensis Wang occurs from Beds 26 to 29 at Meishan and appears to be restricted to the narrow boundary interval immediately above the main mass extinction level in Bed 25. It is suggested that this species is therefore a valuable P-T boundary interval index taxon. Our collections from the Shangsi section confirm that the first occurrence of Hindeodus parvus in that section is about 5 in above the highest level from which a typical Permian fauna is recovered. This may suggest that that some section may be missing at Meishan. The age of the currently defined Permian-Triassic Boundary is estimated by our own studies and a reassessment of previous worker's data at c. 253 Ma, slightly older than our IDTIMS 206Pb/238U age of 252.5 ??0.3 Ma for Bed 28, just 8 cm above the GSSP boundary (Mundil et al., 2001). The age of the main mass extinction, at the base of Bed 25 at Meishan, is estimated at slightly older than 254 Ma based on an age of >254 Ma for the Bed 25 ash. Regardless of the absolute age of the boundary, it is evident that the claimed <165,000 y short duration for the negative carbon isotope excursion at the P-T boundary (Bowring et al., 1998) cannot be confirmed. Purportedly extraterrestrial fullerenes at the boundary (Hecker et al., 2001) have equivocal significance due to their chronostratigraphic non-uniqueness and their occurrence in a volcanic ash.

Dislocation Content Measured Via 3D HR-EBSD Near a Grain Boundary in an AlCu Oligocrystal

NASA Technical Reports Server (NTRS)

Ruggles, Timothy; Hochhalter, Jacob; Homer, Eric

2016-01-01

Interactions between dislocations and grain boundaries are poorly understood and crucial to mesoscale plasticity modeling. Much of our understanding of dislocation-grain boundary interaction comes from atomistic simulations and TEM studies, both of which are extremely limited in scale. High angular resolution EBSD-based continuum dislocation microscopy provides a way of measuring dislocation activity at length scales and accuracies relevant to crystal plasticity, but it is limited as a two-dimensional technique, meaning the character of the grain boundary and the complete dislocation activity is difficult to recover. However, the commercialization of plasma FIB dual-beam microscopes have made 3D EBSD studies all the more feasible. The objective of this work is to apply high angular resolution cross correlation EBSD to a 3D EBSD data set collected by serial sectioning in a FIB to characterize dislocation interaction with a grain boundary. Three dimensional high angular resolution cross correlation EBSD analysis was applied to an AlCu oligocrystal to measure dislocation densities around a grain boundary. Distortion derivatives associated with the plasma FIB serial sectioning were higher than expected, possibly due to geometric uncertainty between layers. Future work will focus on mitigating the geometric uncertainty and examining more regions of interest along the grain boundary to glean information on dislocation-grain boundary interaction.

Modification of Classical SPM for Slightly Rough Surface Scattering with Low Grazing Angle Incidence

NASA Astrophysics Data System (ADS)

Guo, Li-Xin; Wei, Guo-Hui; Kim, Cheyoung; Wu, Zhen-Sen

2005-11-01

Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classical perturbation method at grazing angle is overcome for the vertical polarization at a rough Neumann boundary of infinite extent. The derivation of the formulae and the numerical results show that the backscattering cross section depends on the grazing angle to the fourth power for both Neumann and Dirichlet boundary conditions with low grazing angle incidence. Our results can reduce to that of the classical small perturbation method by neglecting the Neumann and Dirichlet boundary conditions. The project supported by National Natural Science Foundation of China under Grant No. 60101001 and the National Defense Foundation of China

An experimental investigation of turbulent boundary layers along curved surfaces

NASA Technical Reports Server (NTRS)

So, R. M. C.; Mellor, G. L.

1972-01-01

A curved wall tunnel was designed, and an equilibrium turbulent boundary layer was set up on the straight section preceding the curved test section. Turbulent boundary layer flows with uniform and adverse pressure distributions along convex and concave walls were investigated. Hot-wire measurements along the convex surface indicated that turbulent mixing between fluid layers was very much reduced. However, the law of the wall held and the skin friction, thus determined, correlated well with other measurements. Hot-wire measurements along the concave test wall revealed a system of longitudinal vortices inside the boundary layer and confirmed that concave curvature enhances mixing. A self-consistent set of turbulent boundary layer equations for flows along curved surfaces was derived together with a modified eddy viscosity. Solution of these equations together with the modified eddy viscosity gave results that correlated well with the present data on flows along the convex surface with arbitrary pressure distribution. However, it could only be used to predict the mean characteristics of the flow along concave walls because of the existence of the system of longitudinal vortices inside the boundary layer.

Osmium Isotopic Composition of the Sumbar Cretaceous- Tertiary Boundary, Turkmenia

NASA Astrophysics Data System (ADS)

Meisel, T.; Krahenbuhl, U.; Nazarov, M. A.

1992-07-01

Turekian (1982) propagated the use of the osmium isotopic composition as a cosmic indicator for the origin of the high osmium (and iridium) layers at the K/T boundaries. He did not consider the osmium isotopic signature of the terrestrial mantle, which also has a chondritic evolution of the Re-Os system. Osmium cannot serve alone as an infallible indicator of the impact theory, but interesting results can be obtained from their investigation. Different K/T boundary section have been analyzed so far for ^187Os/^186Os. An overview of the values is presented in the table. Boundary Clay layer Os ratio Reference Stevns Klint fish clay 1.66 Luck and Turekian, 1983 Woodside Creek 1.12 Lichte et al., 1986 Raton Basin 1.23 Kraehenbuehl et al., 1988 Raton Basin (several) 1.15-1.23 Esser and Turekian, 1989 Sumbar (0-1 cm) 1.16 This work We obtained a complete marine section of the K/T boundary in southern Turkmenia (decribed by Alekseyev, 1988). It shows a very high Ir concentration (66 ppb) at the boundary layer and a remarkable Ir enrichment over crustal rocks continuing up to 30 cm above the boundary. Our aim of this investigation is to analyze several samples from above and below the boundary for the ^187Os/^186Os ratio to obtain a complete picture of the isotopic evolution of the section. We want to evaluate mixing of Os with chondritic ratios with Os from upper crustal rocks. Another goal is to investigate a mobilization of Os. So far only one sample has been analyzed with NTI-MS after fire assay digestion of the sample. The sample 0 to 1 cm has an ^187Os/^186Os ratio of 1.162 +- 13, which is quite low. We expect an even lower value for the boundary clay (0 cm) itself not taking into account a contribution of radiogenic osmium from the decay of terrestrial rhenium. This might put this K/T boundary section closest of all to the present day chondritic value (approx. 1.05). Further analysis will be presented at the meeting. References Alekseyev A. S., Nazarov M. A., Barsukova L. D., Koselov G. M., Nizhegorodova I. V. and Amanniyazov K. N. (1988) The Cretaceous- Paleogene boundary in southern Turkmenia and its geochemical characteristics. Int. Geol. Rev. 30, 121-135. Esser B. K. and Turekian K. K. (1989) Osmium isotopic composition of the Raton Basin Cretaceous-Tertiary boundary interval. 70, 717. Kraehenbuehl U., Geissbuehler M., Buehler F. and Eberhardt P. (1988) The measurement of osmium isotopes in samples from a Cretaceous/Tertiary (K/T) section of the Raton Basin, USA. Meteoritics 23, 282. Lichte F. E., Wilson S. M., Brooks R. R., Reeves R. D., Holzbecher J. and Ryan D. E. (1986) New method for the measurement of osmium isotopes applied to a New Zealand Cretaceous/Tertiary boundary shale. Nature 322, 816-817. Luck J. M. and Turekian K. K. (1983) Osmium-^187/Osmium-^186 in manganese nodules and the Cretaceous-Tertiary boundary. Science 222, 613- 615. Turekian K. K. (1982) Potential of ^187Os/^186Os as a cosmic versus terrestrial indicator in high iridium layers of sedimentary strata. Geol. Bull. Am. Spec. Pap. 190, 243-249.

27 CFR 9.213 - Snipes Mountain.

Code of Federal Regulations, 2014 CFR

2014-04-01

... beginning point, proceed south along the eastern boundary of section 34 for less than 0.1 mile to its intersection with the 750-foot elevation line, T10N, R22E; then (2) Proceed along the 750-foot elevation line... boundary of section 27, T10N, R21E; then (4) Proceed north in a straight line for less than 0.1 mile to the...

27 CFR 9.213 - Snipes Mountain.

Code of Federal Regulations, 2011 CFR

2011-04-01

... beginning point, proceed south along the eastern boundary of section 34 for less than 0.1 mile to its intersection with the 750-foot elevation line, T10N, R22E; then (2) Proceed along the 750-foot elevation line... boundary of section 27, T10N, R21E; then (4) Proceed north in a straight line for less than 0.1 mile to the...

27 CFR 9.213 - Snipes Mountain.

Code of Federal Regulations, 2012 CFR

2012-04-01

... beginning point, proceed south along the eastern boundary of section 34 for less than 0.1 mile to its intersection with the 750-foot elevation line, T10N, R22E; then (2) Proceed along the 750-foot elevation line... boundary of section 27, T10N, R21E; then (4) Proceed north in a straight line for less than 0.1 mile to the...

27 CFR 9.213 - Snipes Mountain.

Code of Federal Regulations, 2010 CFR

2010-04-01

... beginning point, proceed south along the eastern boundary of section 34 for less than 0.1 mile to its intersection with the 750-foot elevation line, T10N, R22E; then (2) Proceed along the 750-foot elevation line... boundary of section 27, T10N, R21E; then (4) Proceed north in a straight line for less than 0.1 mile to the...

27 CFR 9.213 - Snipes Mountain.

Code of Federal Regulations, 2013 CFR

2013-04-01

... beginning point, proceed south along the eastern boundary of section 34 for less than 0.1 mile to its intersection with the 750-foot elevation line, T10N, R22E; then (2) Proceed along the 750-foot elevation line... boundary of section 27, T10N, R21E; then (4) Proceed north in a straight line for less than 0.1 mile to the...

Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA

USGS Publications Warehouse

Lucas, S.G.; Tanner, L.H.; Donohoo-Hurley, L.; Geissman, J.W.; Kozur, H.W.; Heckert, A.B.; Weems, R.E.

2011-01-01

Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave Formation outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These data include palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four overlapping magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracans) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation, stratigraphically well above the highest occurrence of crurotarsan body fossils or footprints. Correlation to marine sections based on this placement indicates that major terrestrial vertebrate extinctions preceded marine extinctions across the Triassic-Jurassic boundary and therefore were likely unrelated to the Central Atlantic Magmatic Province (CAMP) volcanism. ?? 2011 Elsevier B.V.

Devonian-Carboniferous boundary succession in Eastern Taurides, Turkey

NASA Astrophysics Data System (ADS)

Atakul-Özdemir, Ayşe; Altıner, Demir; Özkan-Altıner, Sevinç

2015-04-01

The succession covering the Devonian-Carboniferous boundary in Eastern Taurides comprises mainly limestones, shales and siltstones. The studied section starts at the base with bioturbated limestones alternating with shales and is followed upwards by platy limestones, and continues with the alternations of bioturbated and platy limestones. Towards the upper part of the succession the alternations of limestone, shales and siltstones reappear again and the top of the section is capped by quartz arenitic sandstone. The studied section spanning the Uppermost Devonian-Lower Carboniferous interval yields a not very abundant, but quite important assemblage of conodont taxa including species of Bispathodus, Polygnathus, Palmatolepis, Spathognathodus and Vogelgnathus. The uppermost Devonian part of the succession is characterized by the presence of Bispathodus costatus, Bispathodus aculeatus aculeatus, Polygnathus communis communis, Palmatolepis gracilis gracilis and Spathognathodus sp.. The Lower Carboniferous in the studied section is represented by the appearance of Polygnathus inornatus and Polygnathus communis communis. Based on the recovered conodont assemblages, Devonian-Carboniferous boundary in Eastern Turides has been determined by the appearance and disappearance of major conodont species.

Calpionellid distribution and microfacies across the Jurassic/ Cretaceous boundary in western Cuba (Sierra de los Órganos)

NASA Astrophysics Data System (ADS)

López-Martínez, Rafael; Barragán, Ricardo; Reháková, Daniela; Cobiella-Reguera, Jorge Luis

2013-06-01

A detailed bed-by-bed sampled stratigraphic section of the Guasasa Formation in the Rancho San Vicente area of the "Sierra de los Órganos", western Cuba, provides well-supported evidence about facies and calpionellid distribution across the Jurassic/Cretaceous boundary. These new data allowed the definition of an updated and sound calpionellid biozonation scheme for the section. In this scheme, the drowning event of a carbonate platform displayed by the facies of the San Vicente Member, the lowermost unit of the section, is dated as Late Tithonian, Boneti Subzone. The Jurassic/Cretaceous boundary was recognized within the facies of the overlying El Americano Member on the basis of the acme of Calpionella alpina Lorenz. The boundary is placed nearly six meters above the contact between the San Vicente and the El Americano Members, in a facies linked to a sea-level drop. The recorded calpionellid bioevents should allow correlations of the Cuban biozonation scheme herein proposed, with other previously published schemes from distant areas of the Tethyan Domain.

Performance tests for the NASA Ames Research Center 20 cm x 40 cm oscillating flow wind tunnel

NASA Technical Reports Server (NTRS)

Cook, W. J.; Giddings, T. A.

1984-01-01

An evaluation is presented of initial tests conducted to assess the performance of the NASA Ames 20 cm x 40 cm oscillating flow wind tunnel. The features of the tunnel are described and two aspects of tunnel operation are discussed. The first is an assessment of the steady mainstream and boundary layer flows and the second deals with oscillating mainstream and boundary layer flows. Experimental results indicate that in steady flow the test section mainstream velocity is uniform in the flow direction and in cross section. The freestream turbulence intensity is about 0.2 percent. With minor exceptions the steady turbulent boundary layer generated on the top wall of the test section exhibits the characteristics of a zero pressure gradient turbulent boundary layer generated on a flat plate. The tunnel was designed to generate sinusoidal oscillating mainstream flows. Experiments confirm that the tunnel produces sinusoidal mainstream velocity variations for the range of frequencies (up to 15 Hz). The results of this study demonstrate that the tunnel essentially produces the flows that it was designed to produce.

78 FR 56650 - Boundary Description and Final Map for Roaring Wild and Scenic River, Mount Hood National Forest...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-13

... DEPARTMENT OF AGRICULTURE Forest Service Boundary Description and Final Map for Roaring Wild and... availability. SUMMARY: In accordance with section 3(b) of the Wild and Scenic Rivers Act, the USDA Forest Service, Washington Office, is transmitting the final boundary description and map of the Roaring Wild and...

78 FR 56650 - Boundary Description and Final Map for Sandy Wild and Scenic River, Upper Portion, Mount Hood...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-13

... DEPARTMENT OF AGRICULTURE Forest Service Boundary Description and Final Map for Sandy Wild and...: Notice of availability. SUMMARY: In accordance with section 3(b) of the Wild and Scenic Rivers Act, the... Sandy Wild and Scenic River, Upper Portion, to Congress. DATES: The boundaries and classification of the...

77 FR 49775 - Boundary Technical Correction for the McKenzie Wild and Scenic River “Lower and Upper Portions...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-17

... DEPARTMENT OF AGRICULTURE Forest Service Boundary Technical Correction for the McKenzie Wild and... Service, USDA. ACTION: Notice of availability. SUMMARY: In accordance with Section 3(b) of the Wild and... for the boundary of the McKenzie Wild and Scenic River ``Lower Portion'' and ``Upper Portion'' to...

Flood boundaries and water-surface profile for the computed 100-year flood, Swift Creek at Afton, Wyoming, 1986

USGS Publications Warehouse

Rankl, James G.; Wallace, Joe C.

1989-01-01

Flood flows on Swift Creek near Afton, Wyoming, were analyzed. Peak discharge with an average recurrence interval of 100 years was computed and used to determine the flood boundaries and water surface profile in the study reach. The study was done in cooperation with Lincoln County and the Town of Afton to determine the extent of flooding in the Town of Afton from a 100-year flood on Swift Creek. The reach of Swift Creek considered in the analysis extends upstream from the culvert at Allred County Road No. 12-135 to the US Geological Survey streamflow-gaging station located in the Bridger National Forest , a distance of 3.2 miles. Boundaries of the 100-year flood are delineated on a map using the computed elevation of the flood at each cross section, survey data, and a 1983 aerial photograph. The computed water surface elevation for the 100-year flood was plotted at each cross section, then the lateral extent of the flood was transferred to the flood map. Boundaries between cross sections were sketched using information taken from the aerial photograph. Areas that are inundated, but not part of the active flow, are designated on the cross sections. (Lantz-PTT)

Analysis of Ground Effects on Aerodynamic Characteristics of Aerofoils Using Boundary Layer Approximation

NASA Astrophysics Data System (ADS)

Takahashi, Yuji; Kikuchi, Masanori; Hirano, Kimitaka

A study of a new high-speed zero-emission transportation “Aerotrain” is being carried out in Tohoku University and the University of Miyazaki. Because the aerotrain utilizes the ground effect, research on the aerofoil section, which can harness the ground effect effectively, is important. The aerotrain moves along a U-shaped guideway, which has a ground and sidewalls, so it has many viscous interference elements. In an analysis of the ground effects on the aerodynamic characteristics of aerofoils, the boundary layers on the aerofoil surface must be considered. At first, velocity distributions on the surfaces of aerofoils in potential flows are computed using the vortex method, then the momentum integration equations of the boundary layer are solved with experimental formulas. This procedure has the following advantages: modifications of the aerofoil section are easy because it is not necessary to make complicated computational grids, boundary layer transition and separation can be predicted using empirical procedures. The aerodynamic characteristics of four types of aerofoil sections are investigated to clarify the relationship between aerofoil sections and ground effects. Computational results are compared with experimental results obtained using a towing wind tunnel to verify computational precisions. In addition, aerofoil characteristics at an actual cruise speed are analyzed.

Asteroid impact vs. Deccan eruptions: The origin of low magnetic susceptibility beds below the Cretaceous-Paleogene boundary revisited

NASA Astrophysics Data System (ADS)

Abrajevitch, Alexandra; Font, Eric; Florindo, Fabio; Roberts, Andrew P.

2015-11-01

The respective roles of an asteroid impact and Deccan Traps eruptions in biotic changes at the Cretaceous-Paleogene (K-Pg) boundary are still debated. In many shallow marine sediments from around the world, the K-Pg boundary is marked by a distinct clay layer that is often underlain by a several decimeter-thick low susceptibility zone. A previous study of the Gubbio section, Italy (Lowrie et al., 1990), attributed low magnetization intensity in this interval to post-depositional dissolution of ferrimagnetic minerals. Dissolution was thought to be a consequence of downward infiltration of reducing waters that resulted from rapid accumulation of organic matter produced by mass extinctions after the K-Pg event. We compare the magnetic properties of sediments from the Gubbio section with those of the Bidart section in southern France. The two sections are similar in their carbonate lithology and the presence of a boundary clay and low susceptibility zone. When compared to background Cretaceous sediments, the low susceptibility zone in both sections is marked by an absence of biogenic magnetite, a decrease in total ferrimagnetic mineral content, and a preferential loss of magnetite with respect to hematite - features that are consistent with reductive dissolution. However, unlike the Gubbio section, where the low susceptibility zone starts immediately below the boundary clay, the low susceptibility zone and the clay layer at Bidart are separated by a ∼4-cm carbonate interval that contains abundant biogenic magnetite. Such separation casts doubt on a causal link between the impact and sediment bleaching. More likely, the low susceptibility layer marks a different environmental event that preceded the impact. An episode of increased atmospheric and oceanic acidity associated with Deccan Traps volcanism that occurred well before the K-Pg impact is argued here to account for the distinct magnetic properties of the low susceptibility intervals.

Computation of airfoil buffet boundaries

NASA Technical Reports Server (NTRS)

Levy, L. L., Jr.; Bailey, H. E.

1981-01-01

The ILLIAC IV computer has been programmed with an implicit, finite-difference code for solving the thin layer compressible Navier-Stokes equation. Results presented for the case of the buffet boundaries of a conventional and a supercritical airfoil section at high Reynolds numbers are found to be in agreement with experimentally determined buffet boundaries, especially at the higher freestream Mach numbers and lower lift coefficients where the onset of unsteady flows is associated with shock wave-induced boundary layer separation.

Carbon isotopic shift and its cause at the Wuchiapingian-Changhsingian boundary in the Upper Permian at the Zhaojiaba section, South China: Evidences from multiple geochemical proxies

NASA Astrophysics Data System (ADS)

Wei, Hengye; Yu, Hao; Wang, Jianguo; Qiu, Zhen; Xiang, Lei; Shi, Guo

2015-06-01

The Late Permian environmental change, connecting the Guadalupian-Lopingian (G-L) (Middle-Upper Permian) boundary mass extinction and the Permain-Triassic (P-Tr) boundary mass extinction, has attracted more and more attentions. A significant negative shift for carbon isotope had been found at the Wuchiapingian-Changhsingian (W-C) boundary in the Upper Permian recently. However, the cause(s) of this negative excursion is still unknown. To resolve this problem, we analyzed the bulk organic carbon isotope, total organic carbon (TOC) content, pyritic sulfur (Spy) content, major element concentrations, and molecular organic biomarkers in the Wujiaping and Dalong formations in the Upper Permian from the Zhaojiaba section in western Hubei province, South China. Our results show that (1) there was a significant negative excursion in organic carbon isotopes at the W-C boundary and again a negative excursion at the top of Changhsingian stage; (2) the significant negative excursion at the W-C boundary was probably a global signal and mainly caused by the low primary productivity; and (3) the negative carbon isotope excursion at the top of Changhsingian was probably caused by the Siberian Traps eruptions. A decline in oceanic primary productivity at the W-C boundary probably represents a disturbance of the marine food web, leading to a vulnerable ecosystem prior to the P-Tr boundary mass extinction.

27 CFR 9.50 - Temecula Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., to the north-south section line dividing Section 23 from Section 24 in Township 8 South, Range 2 West... section line dividing Section 12 from Section 13 in Township 7 South, Range 2 West). (17) The boundary follows this road west to the north-south section line dividing Section 13 from Section 14 in Township 7...

27 CFR 9.50 - Temecula Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., to the north-south section line dividing Section 23 from Section 24 in Township 8 South, Range 2 West... section line dividing Section 12 from Section 13 in Township 7 South, Range 2 West). (17) The boundary follows this road west to the north-south section line dividing Section 13 from Section 14 in Township 7...

Magnetostratigraphy of the Willwood Formation, Bighorn Basin, Wyoming: new constraints on the location of Paleocene/Eocene boundary

USGS Publications Warehouse

Tauxe, L.; Gee, J.; Gallet, Y.; Pick, T.; Bown, T.

1994-01-01

The lower Eocene Willwood Formation in the Bighorn Basin of Wyoming preserves a rich and diverse mammalian and floral record. The paleomagnetic behavior of the sequence of floodplain paleosols of varying degrees of maturation ranges from excellent to poor. We present a magnetostratigraphic section for a composite section near Worland, Wyoming, by using a set of strict criteria for interpreting the step-wise alternating field and thermal demagnetization data of 266 samples from 90 sites throughout the composite section. Correlation to the geomagnetic reversal time scale was achieved by combining magnetostratigraphic and biostratigraphic data from this section, from a section in the Clark's Fork Basin in northern Wyoming, and from DSDP Site 550, with the isotopic data determined on a tuff near the top of our section. Our correlation suggests that the Bighorn Basin composite section in the Worland area spans from within Chron C24r to near the top of Chron C24n, or from approximately 55 to 52 Ma. This correlation places the Paleocene/Eocene boundary within the vicinity of the base of the section. Cryptochron C24r.6 of Cande and Kent is tentatively identified some 100 m above the base of the section. The temporal framework provided here enables correlation of the mammalian biostratigraphy of the Bighorn Basin to other continental sequences as well as to marine records. It also provides independent chronological information for the calculation of sediment accumulation rates to constrain soil maturation rates. We exclude an age as young as 53 Ma for the Paleocene/Eocene boundary and support older ages, as recommended in recent time scales. The location of a tuff dated at 52.8 ?? 0.3 Ma at the older boundary C24n.1 is consistent with the age of 52.5 Ma estimated by Cande and Kent and inconsistent with that of 53.7 Ma, from Harland et al. ?? 1994.

Statistical investigation of avalanches of three-dimensional small-world networks and their boundary and bulk cross-sections

NASA Astrophysics Data System (ADS)

Najafi, M. N.; Dashti-Naserabadi, H.

2018-03-01

In many situations we are interested in the propagation of energy in some portions of a three-dimensional system with dilute long-range links. In this paper, a sandpile model is defined on the three-dimensional small-world network with real dissipative boundaries and the energy propagation is studied in three dimensions as well as the two-dimensional cross-sections. Two types of cross-sections are defined in the system, one in the bulk and another in the system boundary. The motivation of this is to make clear how the statistics of the avalanches in the bulk cross-section tend to the statistics of the dissipative avalanches, defined in the boundaries as the concentration of long-range links (α ) increases. This trend is numerically shown to be a power law in a manner described in the paper. Two regimes of α are considered in this work. For sufficiently small α s the dominant behavior of the system is just like that of the regular BTW, whereas for the intermediate values the behavior is nontrivial with some exponents that are reported in the paper. It is shown that the spatial extent up to which the statistics is similar to the regular BTW model scales with α just like the dissipative BTW model with the dissipation factor (mass in the corresponding ghost model) m2˜α for the three-dimensional system as well as its two-dimensional cross-sections.

Wind-tunnel interference with particular reference to off-center positions of the wing and to the downwash at the tail

NASA Technical Reports Server (NTRS)

Silverstein, Abe; White, James A

1937-01-01

The theory of wind tunnel boundary influence on the downwash from a wing has been extended to provide more complete corrections for application to airplane test data. The first section of the report gives the corrections of the lifting line for wing positions above or below the tunnel center line; the second section shows the manner in which the induced boundary influence changes with distance aft of the lifting line. Values of the boundary corrections are given for off-center positions of the wing in circular, square, 2:1 rectangular, and 2:1 elliptical tunnels. Aft of the wing the corrections are presented for only the square and the 2:1 rectangular tunnels, but it is believed that these may be applied to jets of circular and 2:1 elliptical cross sections. In all cases results are included for both open and closed tunnels.

Heat transfer through turbulent boundary layers - The effects of introduction of and recovery from convex curvature

NASA Technical Reports Server (NTRS)

Simon, T. W.; Moffat, R. J.

1979-01-01

Measurements have been made of the heat transfer through a turbulent boundary layer on a convexly curved isothermal wall and on a flat plate following the curved section. Data were taken for one free-stream velocity and two different ratios of boundary layer thickness to radius of curvature delta/R = 0.051 and delta/R = 0.077. Only small differences were observed in the distribution of heat transfer rates for the two boundary layer thicknesses tested, although differences were noted in the temperature distributions within the boundary layer

Inverse Thermal Analysis of Alloy 690 Laser and Hybrid Laser-GMA Welds Using Solidification-Boundary Constraints

NASA Astrophysics Data System (ADS)

Lambrakos, S. G.

2017-08-01

An inverse thermal analysis of Alloy 690 laser and hybrid laser-GMA welds is presented that uses numerical-analytical basis functions and boundary constraints based on measured solidification cross sections. In particular, the inverse analysis procedure uses three-dimensional constraint conditions such that two-dimensional projections of calculated solidification boundaries are constrained to map within experimentally measured solidification cross sections. Temperature histories calculated by this analysis are input data for computational procedures that predict solid-state phase transformations and mechanical response. These temperature histories can be used for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes.

Shock wave boundary layer interaction on suction side of compressor profile in single passage test section

NASA Astrophysics Data System (ADS)

Flaszynski, Pawel; Doerffer, Piotr; Szwaba, Ryszard; Kaczynski, Piotr; Piotrowicz, Michal

2015-11-01

The shock wave boundary layer interaction on the suction side of transonic compressor blade is one of the main objectives of TFAST project (Transition Location Effect on Shock Wave Boundary Layer Interaction). In order to investigate the flow structure on the suction side of a profile, a design of a generic test section in linear transonic wind tunnel was proposed. The experimental and numerical results for the flow structure investigations are shown for the flow conditions as the existing ones on the suction side of the compressor profile. Near the sidewalls the suction slots are applied for the corner flow structure control. It allows to control the Axial Velocity Density Ratio (AVDR), important parameter for compressor cascade investigations. Numerical results for Explicit Algebraic Reynolds Stress Model with transition modeling are compared with oil flow visualization, schlieren and Pressure Sensitive Paint. Boundary layer transition location is detected by Temperature Sensitive Paint.

Prediction of the Stress-Strain Behavior of Open-Cell Aluminum Foam under Compressive Loading and the Effects of Various RVE Boundary Conditions

NASA Astrophysics Data System (ADS)

Hamidi Ghaleh Jigh, Behrang; Farsi, Mohammad Ali; Hosseini Toudeshky, Hossein

2018-05-01

The prediction of the mechanical behavior of metallic foams with realistic microstructure and the effects of various boundary conditions on the mechanical behavior is an important and challenging issue in modeling representative volume elements (RVEs). A numerical investigation is conducted to determine the effects of various boundary conditions and cell wall cross sections on the compressive mechanical properties of aluminum foam, including the stiffness, plateau stress and onset strain of densification. The open-cell AA6101-T6 aluminum foam Duocel is used in the analyses in this study. Geometrical characteristics including the cell size, foam relative density, and cross-sectional shape and thickness of the cell walls are extracted from images of the foam. Then, the obtained foam microstructure is analyzed as a 2D model. The ligaments are modeled as shear deformable beams with elastic-plastic material behavior. To prevent interpenetration of the nodes and walls inside the cells with large deformations, self-contact-type frictionless interaction is stipulated between the internal surfaces. Sensitivity analyses are performed using several boundary conditions and cells wall cross-sectional shapes. The predicted results from the finite element analyses are compared with the experimental results. Finally, the most appropriate boundary conditions, leading to more consistent results with the experimental data, are introduced.

Prediction of the Stress-Strain Behavior of Open-Cell Aluminum Foam under Compressive Loading and the Effects of Various RVE Boundary Conditions

NASA Astrophysics Data System (ADS)

Hamidi Ghaleh Jigh, Behrang; Farsi, Mohammad Ali; Hosseini Toudeshky, Hossein

2018-04-01

The prediction of the mechanical behavior of metallic foams with realistic microstructure and the effects of various boundary conditions on the mechanical behavior is an important and challenging issue in modeling representative volume elements (RVEs). A numerical investigation is conducted to determine the effects of various boundary conditions and cell wall cross sections on the compressive mechanical properties of aluminum foam, including the stiffness, plateau stress and onset strain of densification. The open-cell AA6101-T6 aluminum foam Duocel is used in the analyses in this study. Geometrical characteristics including the cell size, foam relative density, and cross-sectional shape and thickness of the cell walls are extracted from images of the foam. Then, the obtained foam microstructure is analyzed as a 2D model. The ligaments are modeled as shear deformable beams with elastic-plastic material behavior. To prevent interpenetration of the nodes and walls inside the cells with large deformations, self-contact-type frictionless interaction is stipulated between the internal surfaces. Sensitivity analyses are performed using several boundary conditions and cells wall cross-sectional shapes. The predicted results from the finite element analyses are compared with the experimental results. Finally, the most appropriate boundary conditions, leading to more consistent results with the experimental data, are introduced.

Late Quaternary Surface Displacement Across a Normal-Fault Structural Boundary on the Northern Lost River Fault Zone (Idaho, USA)

NASA Astrophysics Data System (ADS)

DuRoss, C. B.; Bunds, M. P.; Reitman, N. G.; Gold, R. D.; Personius, S. F.; Briggs, R. W.; Toke, N. A.; Johnson, K. L.; Lajoie, L. J.

2017-12-01

In 1983, about 36 km of the 130-km-long multisegment Lost River fault zone (LRFZ) (Idaho, USA) ruptured in the M 6.9 Borah Peak earthquake. Normal-faulting surface rupture propagated along the entire 24-km-long Thousand Springs section, then branched to the northwest along a 4-km-long fault (western section) that continues into the Willow Creek Hills, a prominent bedrock ridge that forms a structural boundary between the Thousand Springs section and Warms Springs section to the north. North of the Willow Creek Hills, the 1983 rupture continued onto the southern 8 km of the 16-km-long Warm Springs section. To improve our understanding of the Borah Peak earthquake and the role of structural boundaries in normal-fault rupture propagation, we acquired low-altitude aerial imagery of the southern 8 km of the Warm Springs section and northern 6 km of the Thousand Springs section, including the western section branch fault. Using 5-10-cm-pixel digital surface models generated from this dataset, we measured vertical surface offsets across both 1983 and prehistoric scarps. On the Warm Springs section, 1983 displacement is minor (mean of 0.3 m) compared to at least two prehistoric events having mean displacements of 1.1 m and 1.7 m inferred from displacement difference curves. Prehistoric scarps on the western section indicate rupture of this branch fault prior to 1983. Correcting for 1983 displacement, mean prehistoric displacement on the western section is 0.9 m compared to a mean of 0.7 m in 1983. Using these data and previous paleoseismic displacements, we evaluate the spatial distribution of cumulative and per-earthquake displacement. Our results suggest that at least one prehistoric rupture of the Thousand Springs section occurred with a similar length and displacement to that in 1983. Further, the 1983 spillover rupture from the Thousand Springs section to the southernmost Warm Springs section appears unique from larger displacement, prehistoric ruptures that may have spanned the majority of the Warm Springs section and possibly continued south into the Willow Creek Hills based on paleoseismic and surface-offset data. We conclude that the Willow Creek Hills structural boundary has likely moderated, but not completely impeded both prehistoric and 1983 ruptures of the northern LRFZ.

Fluctuating disturbances in a Mach 5 wind tunnel

NASA Technical Reports Server (NTRS)

Anders, J. B.; Stainback, P. C.; Beckwith, I. E.; Keefe, L. R.

1976-01-01

An experimental investigation has been conducted to determine the source and nature of disturbances in the settling chamber and test section of a Mach 5 wind tunnel. Various changes in the air supply piping to the wind tunnel are shown to influence the disturbance levels in the settling chamber. These levels were reduced by the use of an acoustic muffler section in the settling chamber. Three nozzles were tested with the same settling chamber and hot-wire measurements indicated that the test section disturbances were entirely acoustic. Significant reductions in the test section noise levels were obtained with an electroplated nozzle utilizing boundary-layer removal upstream of the throat. The source of test section noise is shown to be different for laminar and turbulent nozzle-wall boundary layers.

Investigation of a marine magnetic polarity reversal boundary in cross-section at the northern boundary of the Kane Megamullion, Mid-Atlantic Ridge 23°40'N

NASA Astrophysics Data System (ADS)

Xu, M.; Tivey, M.

2016-12-01

Near-bottom magnetic field measurements made by the submersible Nautile during the 1992 Kanaut Expedition define the cross-sectional geometry of magnetic polarity reversal boundaries and the vertical variation of crustal magnetization in lower oceanic crust exposed along the Kane Transform Fault (TF) at the northern boundary of the Kane Megamullion (KMM). The KMM exposes lower crust and upper mantle rocks on a low-angle normal fault that was active between 3.3 Ma and 2.1 Ma. The geometry of the polarity boundaries is estimated from an inversion of the submarine magnetic data for crustal magnetization. In general, the polarity boundaries dip away from the ridge axis along the Kane TF scarp, with a west-dipping angle of 45° in the shallow (<1 km) crust and <20° in the deeper crust. The existence of the magnetic polarity boundaries (e.g. C2r.2r/C2An.1n, 2.581 Ma) indicates that the lower crustal gabbros and upper mantle serpentinized peridotites are able to record a coherent magnetic signal. Our results support the conclusion of Williams [2007] that the lower crust cools through the Curie temperature of magnetite to become magnetic, with the polarity boundaries representing both frozen isotherms and isochrons. We also test the effects of the rotation of this isotherm structure and/or footwall rotation, and find that the magnetic polarity boundary geometry is not sensitive to these directional changes.

Investigation of a marine magnetic polarity reversal boundary in cross section at the northern boundary of the Kane Megamullion, Mid-Atlantic Ridge, 23°40'N

NASA Astrophysics Data System (ADS)

Xu, Min; Tivey, M. A.

2016-05-01

Near-bottom magnetic field measurements made by the submersible Nautile during the 1992 Kanaut Expedition define the cross-sectional geometry of magnetic polarity reversal boundaries and the vertical variation of crustal magnetization in lower oceanic crust exposed along the Kane Transform Fault (TF) at the northern boundary of the Kane Megamullion (KMM). The KMM exposes lower crust and upper mantle rocks on a low-angle normal fault that was active between 3.3 Ma and 2.1 Ma. The geometry of the polarity boundaries is estimated from an inversion of the submarine magnetic data for crustal magnetization. In general, the polarity boundaries dip away from the ridge axis along the Kane TF scarp, with a west dipping angle of ~45° in the shallow (<1 km) crust and <20° in the deeper crust. The existence of the magnetic polarity boundaries (e.g., C2r.2r/C2An.1n, ~2.581 Ma) indicates that the lower crustal gabbros and upper mantle serpentinized peridotites are able to record a coherent magnetic signal. Our results support the conclusion of Williams (2007) that the lower crust cools through the Curie temperature of magnetite to become magnetic, with the polarity boundaries representing both frozen isotherms and isochrons. We also test the effects of the rotation of this isotherm structure and/or footwall rotation and find that the magnetic polarity boundary geometry is not sensitive to these directional changes.

Application of a boundary element method to the study of dynamical torsion of beams

NASA Technical Reports Server (NTRS)

Czekajski, C.; Laroze, S.; Gay, D.

1982-01-01

During dynamic torsion of beam elements, consideration of nonuniform warping effects involves a more general technical formulation then that of Saint-Venant. Nonclassical torsion constants appear in addition to the well known torsional rigidity. The adaptation of the boundary integral element method to the calculation of these constants for general section shapes is described. The suitability of the formulation is investigated with some examples of thick as well as thin walled cross sections.

An Observational Study of the Kuroshio in the East China Sea: Local, Regional, and Basin-Wide Perspectives on a Western Boundary Current

DTIC Science & Technology

2008-01-01

a seamount (summit ~320 m depth); the northern section reaches ~460 m depth while the southern section reaches ~1400 m (Oka and Kawabe, 2003). East...AN OBSERVATIONAL STUDY OF THE KUROSHIO IN THE EAST CHINA SEA: LOCAL, REGIONAL, AND BASIN-WIDE PERSPECTIVES ON A WESTERN BOUNDARY CURRENT...BY MAGDALENA ANDRES A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF

Physics of magnetospheric boundary layers

NASA Technical Reports Server (NTRS)

Cairns, I. H.

1993-01-01

The central ideas of this grant are that the magnetospheric boundary layers link disparate regions of the magnetosphere together, and the global behavior of the magnetosphere can be understood only by understanding the linking mechanisms. Accordingly the present grant includes simultaneous research on the global, meso-, and micro-scale physics of the magnetosphere and its boundary layers. These boundary layers include the bow shock, magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical and simulation projects have been performed on these subjects, as well as comparison of theoretical results with observational data. Very good progress has been made, with four papers published or in press and two additional papers submitted for publication during the six month period 1 June - 30 November 1993. At least two projects are currently being written up. In addition, members of the group have given papers at scientific meetings. The further structure of this report is as follows: section two contains brief accounts of research completed during the last six months, while section three describes the research projects intended for the grant's final period.

Characterization of the Boundary Layers on Full-Scale Bluefin Tuna

DTIC Science & Technology

2014-09-30

NUWC-NPT Technical Report 12,163 30 September 2014 Characterization of the Boundary Layers on Full-Scale Bluefin Tuna Kimberly M. Cipolla...Center Division Newport, under Section 219 Research Project, “Characterization of the Boundary Layers on Full-Scale Bluefin Tuna ,” principal...K. Amaral (Code 1522). The author thanks Barbara Block (Stanford University), head of the Tuna Research and Conservation Center (TRCC) at the

Importance of carbon isotopic data of the Permian-Triassic boundary layers in the Verkhoyansk region for the global correlation of the basal Triassic layer

NASA Astrophysics Data System (ADS)

Zakharov, Yu. D.; Biakov, A. S.; Richoz, S.; Horacek, M.

2015-01-01

This paper is dedicated to a global correlation of marine Permian-Triassic boundary layers on the basis of partially published and original data on the δ13Corg and δ13Ccarb values of the Suol section (Setorym River, South Verkhoyansk region). The section consists of six carbon isotopic intervals, which are easily distinguishable in the carbon isotopic curves for a series of Permian-Triassic reference sections of Eurasia and Northern America, including paleontologically described sections of Central Iran, Kashmir, and Southern China. This suggests that the Permian-Triassic boundary in the Suol section is close to the carbon isotopic minimum of interval IV. In light of new data, we suggest considering the upper part of the Late Permian Changhsingian Stage and the lower substage of the Early Triassic Induan Stage of Siberia in the volumes of the rank Otoceras concavum zone and the Tompophiceras pascoei and Wordieoceras decipiens zones, respectively. The O. concavum zone of the Verkhoyansk region probably corresponds to the Late Changhsingian Hypophiceras triviale zone of Greenland. The carbon isotopic intervals II, III, IV, and V in the Permian-Triassic boundary layers of the Verkhoyansk region traced in a series of the reference sections of Eurasia correspond, most likely, to intensification of volcanic activity at the end of the Late Changhsingian and to the first massive eruptions of Siberian traps at the end of the Changhsingian and the beginning of the Induan Stages. New data indicate the possible survival of ammonoids of the Otoceratoidea superfamily at the species level after mass extinction of organisms at the end of the Permian.

Water-surface profile and flood boundaries for the computed 100-year flood, lower Salt River, Lincoln County, Wyoming

USGS Publications Warehouse

Miller, Kirk A.; Mason, John P.

2000-01-01

The water-surface profile and flood boundaries for the computed 100-year flood were determined for a part of the lower Salt River in Lincoln County, Wyoming. Channel cross-section data were provided by Lincoln County. Cross-section data for bridges and other structures were collected and compiled by the U.S. Geological Survey. Roughness coefficients ranged from 0.034 to 0.100. The 100-year flood was computed using standard methods, ranged from 5,170 to 4,120 cubic feet per second through the study reach, and was adjusted proportional to contributing drainage area. Water-surface elevations were determined by the standard step-backwater method. Flood boundaries were plotted on digital basemaps.

Calculations of Laminar Heat Transfer Around Cylinders of Arbitrary Cross Section and Transpiration-Cooled Walls with Application to Turbine Blade Cooling

NASA Technical Reports Server (NTRS)

Eckert, E.R.G.; Livingood, John N.B.

1951-01-01

An approximate method for development of flow and thermal boundary layers in laminar regime on cylinders with arbitrary cross section and transpiration-cooled walls is obtained by use of Karman's integrated momentum equation and an analogous heat-flow equation. Incompressible flow with constant property values throughout boundary layer is assumed. Shape parameters for approximated velocity and temperature profiles and functions necessary for solution of boundary-layer equations are presented as charts, reducing calculations to a minimum. The method is applied to determine local heat-transfer coefficients and surface temperature-cooled turbine blades for a given flow rate. Coolant flow distributions necessary for maintaining uniform blade temperatures are also determined.

Flow study in the cross sectional planes of a turbine scroll

NASA Technical Reports Server (NTRS)

Hamed, A.; Abdallah, S.; Tabakoff, W.

1977-01-01

A numerical study of the nonviscous flow characteristics in the cross-sectional planes of a radial inflow turbine scroll is presented. The velocity potential is used in the formulation to determine the flow velocity in these planes resulting from the continuous mass discharge. The effect of the through flow velocity is simulated by a continuous distribution of source/sink in the cross-section. A special iterative procedure is devised to handle the solution of the resulting Poisson's differential equation with Neumann boundary conditions in a domain with generally curved boundaries. The analysis is used to determine the effects of the radius of curvature, the location of the scroll section and its geometry on the flow characteristics in the turbine scroll.

The liquid fuel jet in subsonic crossflow

NASA Technical Reports Server (NTRS)

Nguyen, T. T.; Karagozian, A. R.

1990-01-01

An analytical/numerical model is described which predicts the behavior of nonreacting and reacting liquid jets injected transversely into subsonic cross flow. The compressible flowfield about the elliptical jet cross section is solved at various locations along the jet trajectory by analytical means for free-stream local Mach number perpendicular to jet cross section smaller than 0.3 and by numerical means for free-stream local Mach number perpendicular to jet cross section in the range 0.3-1.0. External and internal boundary layers along the jet cross section are solved by integral and numerical methods, and the mass losses due to boundary layer shedding, evaporation, and combustion are calculated and incorporated into the trajectory calculation. Comparison of predicted trajectories is made with limited experimental observations.

Is there evidence for Cretaceous-Tertiary boundary-age deep-water deposits in the Caribbean and Gulf of Mexico?

NASA Astrophysics Data System (ADS)

Keller, G.; MacLeod, N.; Lyons, J. B.; Officer, C. B.

1993-09-01

Over most of the Gulf of Mexico and Caribbean a hiatus is present between the lower upper Maastrichtian and lowermost Tertiary deposits; sedimentation resumed ˜200 ka (upper zone Pla) after the K-T boundary. Current-bedded volcaniclastic sedimentary rocks at Deep Sea Drilling Project (DSDP) Sites 536 and 540, which were previously interpreted as impact-generated megawave deposits of K-T boundary age, are biostratigraphically of pre-K-T boundary age and probably represent turbidite or gravity-How deposits. The top 10 to 20 cm of this deposit at Site 536 contains very rare Micula prinsii, the uppermost Maastrichtian index taxon, as well as low values of Ir (0.6 pbb) and rare Ni-rich spinels. These indicate possible reworking of sediments of K-T boundary age at the hiatus. Absence of continuous sediment accumulation across the K-T boundary in the 16 Gulf of Mexico and Caribbean sections examined prevents their providing evidence of impact-generated megawave deposits in this region. Our study indicates that the most complete trans-K-T stratigraphic records may be found in onshore marine sections of Mexico, Cuba, and Haiti. The stratigraphic records of these areas should be investigated further for evidence of impact deposits.

How to teach geocomplexity at two opposite levels? The 'Klippen of Cabrières' case study (Hérault, France).

NASA Astrophysics Data System (ADS)

Giusti, Christian

2014-05-01

The starting point of this essay is a question from a school teacher who came in contact with me via my photo gallery online. His question, "What is the origin of the Roc de Murviel?" actually covers three or four separate problems, and requires to devise simple and specific comparisons in order to help children of 8 years old to understand a bunch of difficult and abstract concepts. But, in contrast, Carboniferous marine sedimentary deposits of the so-called unit "Klippen of Cabrières" are known of geologists worldwide, due to the presence of a Global boundary Stratotype Section and Point (GSSP) located not far from the "Roc de Murviel", the "La Serre" section, where is defined the base of the Carboniferous System, Mississippian Sub-System and Tournaisien Stage. In this case, to remind how the conceptions about the formation of the "Klippen of Cabrières" evolved may serve as an introduction to the explanation of syntectonic sedimentation and to the history of the concept of thrust nappe for the well-trained public as well as academics or engineers not experts in the specificities of regional geology. Difficulty (at least in France) will come from the scarcity of naturalists, a species in danger of extinction, and from the small number of historians concerned by the natural sciences. At the public school, the first method is to decompose the problem into independent issues (Cartesian reductionism) such as: nature and age of the rock? mode of sedimentation? part of an ancient mountain chain? existence as a landform in the current landscape? Concerning the specific question of geological time, because most children of this age do not yet know how to read the time, a second method is to replace the model of the clock (the entire history of the planet Earth reduced to one year) by the metaphor of either the staircase or the ladder, both adapted from the international stratigraphic scale. A third method is to use the concept of "toolbox" for each sub-disciplines or specialties required: inorganic chemistry, paleontology, structural geology, geomorphology. For the public of motivated adults, it may be helpful to remember the key milestones of one century of regional geology: first detailed geological mapping by Paul Gervais de Rouville in the 1870s, Jules Bergeron's "nappe de recouvrement" inspired by the work of Marcel Bertrand in Provence and Switzerland, Bernard Gèze's "nappe-pli couché" derived on Pierre Termier's "nappe du premier genre" in the Alps, the widespread use of sedimentological and micro-tectonic criteria after Second World War (though formerly implemented by André Demay in the Cévennes before 1939), with the studies of Lamoraal Ulbo Sitter, Rodolphe Trümpy and John Rodgers in the 1950s up to those of Maurice Mattauer, François Proust and François Arthaud in the early 1970s. Regarding the teaching of geological time, the issue will be addressed ex situ with the help of the clock model defined above, and could be completed by fieldwork with the observation in situ of one of the real "bars" of the stratigraphic "ladder", i.e. the GSSP's of La Serre section. Two other points are situated nearby: the Coumiac quarry near Cessenon (base of the Famennian Stage) and the Col du Puech de la Suque (base of the Frasnian Stage and Upper Devonian Sub-System). Fieldwork is aimed to link the study of geodiversity to that of biodiversity, in addition to paleontology, paleogeography and the reconstruction of palaeoenvironments.

Paleomagnetic data from the Pignola 2 section (Southern Apennines, Italy) and the Dibona section (Dolomites, Italy): a contribution to the Carnian magnetostratigraphy

NASA Astrophysics Data System (ADS)

Maron, Matteo; Muttoni, Giovanni; Guido, Roghi; Mazza, Michele; Manuel, Rigo

2015-04-01

New magnetostratigraphic data for the Carnian have been obtained from the Pignola 2 section (Southern Apennines, Italy) and the Dibona section (Dolomites, Italy), obtaining 6 and 9 magnetozones respectively, both calibrated with conodonts and pollens. These new data cover the Julian/Tuvalian interval (Carnian) that is currently lacking of a clear magnetostratigraphic record. The Pignola 2 and Dibona sections have been compared with the magnetostratigraphy of other Tethyan sections from literature (e.g. Pizzo Mondello, Silická Brezová, Bolücektasi Tepe), integrating the magnetostratigraphy of the Carnian around the Julian/Tuvalian boundary. Considering also the sections of Mayerling and Prati di Stuores, containing the Ladinian/Carnian boundary, we obtained a continuous magnetostratigraphy for the Carnian Stage. Sections like Pizzo Mondello and Silická Brezová span from the late Carnian to the late Norian and have been correlated with Norian/Rhaetian sections up to the Hettangian base, like Pignola-Abriola, Steinbergkogel, Brumano-Italcementi Quarry. This sequence of correlations reveals a continuous magnetostratigraphic record along the whole Late Triassic valid for the Tethyan realm. The radiometric age from the Pignola 2 section (230.91±0.33 Ma from the "green clay-radiolaritic horizon") and the recent proposal for the age of the Rhaetian base (205.7 Ma from the Pignola-Abriola section, obtained by means of correlation with the Newark Astrochronological Polarity Time Scale and coherent with recent radiometric ages around the Norian/Rhaetian boundary), constrain our Late Triassic Tethyan composite magnetostratigraphy to a well-defined time interval, therefore improving current versions of the Triassic time scale.

Grain boundary engineering for control of tellurium diffusion in GH3535 alloy

NASA Astrophysics Data System (ADS)

Fu, Cai-Tao; Yinling, Wang; Chu, Xiang-Wei; Jiang, Li; Zhang, Wen-Zhu; Bai, Qin; Xia, Shuang; Leng, Bin; Li, Zhi-Jun; Ye, Xiang-Xi; Liu, Fang

2017-12-01

The effect of grain boundary engineering (GBE) on the Te diffusion along the surface grain boundaries was investigated in GH3535 alloy. It can be found that GBE treatment increases obviously the fraction of low-Σ coincidence site lattice (CSL) boundaries, especially the Σ3 ones, and introduces the large-size grain clusters. When the as-received (AR) and GBE-treated (GBET) specimens were exposed to Te vapor, only Σ3 boundaries were found to be resistant to Te diffusion. From the cross section and the surface, the fewer Te-attacked grain boundaries and the thinner corrosion layer can be observed in the GBET sample. The improvement of resistance to Te diffusion in the GBET sample can be attributed to the large size grain-clusters associated with high proportion of the Σ3n boundaries.

The Cretaceous/Paleogene Transition on the East Tasman Plateau, Southwestern Pacific

NASA Technical Reports Server (NTRS)

Schellenberg, Stephen A.; Brinkhuis, Henk; Stickley, Catherine E.; Fuller, Michael; Kyte, Frank T.; Williams, Graham L.

2004-01-01

Ocean Drilling Program Leg 189 recovered a potentially complete shallow marine record of the Cretaceous-Paleogene boundary (KPB) at Site 1172 on the East Tasman Plateau. Here we present high-resolution (cm-scale) data from micropaleontology, geochemistry, sedimentology, and paleomagnetism that provide no evidence for a complete KPB, but instead suggest a boundary-spanning hiatus of at least 0.8 Ma. We interpret this hiatus to represent the sequence boundary between the uppermost Maastrichtian Tal.1 and lowermost Danian Ta1.2/ Da- 1 3rd-order sequence stratigraphic cycles. Microfloral assemblages indicate generally shallow paleodepths, restricted circulation, and eutrophic conditions through the section. Paleodepths progressively shallow through the late Maastrichtian, while more oceanic and warmer conditions dominate the early Danian. The Site 1172 KPB section is broadly comparable to other southern highlatitude sections in Antarctica and New Zealand, but appears to record a shallower and more restricted environment that permitted a eustatically-driven hiatus across the KPB mass extinction event.

22 CFR 1104.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION... Commission, United States and Mexico, and his delegate. (d) Public lands means lands to which the United... Boundary and Water Commission, United States and Mexico. (e) Indian tribe as defined in the Act means any...

Timing of the End-Triassic Extinctions on Land: the Moenave Formation on the Southern Colorado Plateau, USA

NASA Astrophysics Data System (ADS)

Lucas, S. G.; Tanner, L. H.; Geissman, J. W.; Hurley, L. L.; Kozur, H.; Heckert, A.; Kuerschner, W.; Weems, R.

2010-12-01

Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, USA represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present here a synthesis of new biostratigraphic and magnetostratigraphic data collected from the Moenave Formation across the outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These include, palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracan) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation. This placement supports the conclusion that terrestrial extinctions preceded marine extinctions across the Triassic-Jurassic boundary and likely were unrelated to CAMP volcanism.

LDV measurement of boundary layer on rotating blade surface in wind tunnel

NASA Astrophysics Data System (ADS)

Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Suzuki, Daiki; Kaga, Norimitsu; Kagisaki, Yosuke

2014-12-01

Wind turbines generate electricity due to extracting energy from the wind. The rotor aerodynamics strongly depends on the flow around blade. The surface flow on the rotating blade affects the sectional performance. The wind turbine surface flow has span-wise component due to span-wise change of airfoil section, chord length, twisted angle of blade and centrifugal force on the flow. These span-wise flow changes the boundary layer on the rotating blade and the sectional performance. Hence, the thorough understanding of blade surface flow is important to improve the rotor performance. For the purpose of clarification of the flow behaviour around the rotor blade, the velocity in the boundary layer on rotating blade surface of an experimental HAWT was measured in a wind tunnel. The velocity measurement on the blade surface was carried out by a laser Doppler velocimeter (LDV). As the results of the measurement, characteristics of surface flow are clarified. In optimum tip speed operation, the surface flow on leading edge and r/R=0.3 have large span-wise velocity which reaches 20% of sectional inflow velocity. The surface flow inboard have three dimensional flow patterns. On the other hand, the flow outboard is almost two dimensional in cross sectional plane.

Use of Section 18 Emergency Exemption and Section 24(c) Special Local Need Products in Indian Country

EPA Pesticide Factsheets

This finding provides for use of registered section 18 and section 24(c) products in areas of Indian country that are within the geographic boundaries of the state(s) or county(ies) where the emergency exemption or special local need registration applies.

Antecedents of Emotional Intelligence: An Empirical Study

ERIC Educational Resources Information Center

Barbuto, John E., Jr.; Story, Joana S.

2010-01-01

This study examined the relationships between emotional intelligence, locus of control, and mental boundaries. Three hundred and eighty-two county employees were sampled using a cross-sectional survey design. The results indicated internal locus of control and thin mental boundaries are positively related to emotional intelligence. A hierarchical…

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of changing field boundaries. When field boundaries are changed to include areas of land that were... Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria. (a...

23 CFR 450.312 - Metropolitan planning area boundaries.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Metropolitan planning area boundaries. 450.312 Section 450.312 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH... descriptions shall be submitted either as a geo-spatial database or described in sufficient detail to enable...

15 CFR 922.181 - Boundary.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the east side of Lanai; to the waters seaward of the three nautical mile limit north of Kahoolawe, to... MARINE SANCTUARY PROGRAM REGULATIONS Hawaiian Islands Humpback Whale National Marine Sanctuary § 922.181 Boundary. (a) Except for excluded areas described in paragraph (b) of this section, the Hawaiian Islands...

15 CFR 922.181 - Boundary.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the east side of Lanai; to the waters seaward of the three nautical mile limit north of Kahoolawe, to... MARINE SANCTUARY PROGRAM REGULATIONS Hawaiian Islands Humpback Whale National Marine Sanctuary § 922.181 Boundary. (a) Except for excluded areas described in paragraph (b) of this section, the Hawaiian Islands...

15 CFR 922.181 - Boundary.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the east side of Lanai; to the waters seaward of the three nautical mile limit north of Kahoolawe, to... MARINE SANCTUARY PROGRAM REGULATIONS Hawaiian Islands Humpback Whale National Marine Sanctuary § 922.181 Boundary. (a) Except for excluded areas described in paragraph (b) of this section, the Hawaiian Islands...

15 CFR 922.181 - Boundary.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the east side of Lanai; to the waters seaward of the three nautical mile limit north of Kahoolawe, to... MARINE SANCTUARY PROGRAM REGULATIONS Hawaiian Islands Humpback Whale National Marine Sanctuary § 922.181 Boundary. (a) Except for excluded areas described in paragraph (b) of this section, the Hawaiian Islands...

Computer program for design of two-dimensional supersonic turbine rotor blades with boundary-layer correction

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Scullin, V. J.

1971-01-01

A FORTRAN 4 computer program for the design of two-dimensional supersonic rotor blade sections corrected for boundary-layer displacement thickness is presented. The ideal rotor is designed by the method of characteristics to produce vortex flow within the blade passage. The boundary-layer parameters are calculated by Cohen and Reshotoko's method for laminar flow and Sasman and Cresci's method for turbulent flow. The program input consists essentially of the blade surface Mach number distribution and total flow conditions. The primary output is the corrected blade profile and the boundary-layer parameters.

Backscattering and extinction cross sections of two swimbladdered fishes at the lowest resonance, as modeled by the boundary-element method

NASA Astrophysics Data System (ADS)

Foote, Kenneth G.; Francis, David T. I.

2003-04-01

The boundary-element method has been applied to backscattering and extinction of sound by swimbladdered fish at the lowest, breathing-mode resonance. Corresponding cross sections have been computed for specimens of two representative kinds of swimbladder-bearing fish, namely physostomes and physoclists, which, respectively, possess and lack an external duct. The respective fishes are herring (Clupea harengus) and pollack (Pollachius pollachius), for which swimbladder morphometric data are available. The depth dependences of the cross sections are computed over the range 0-500 m. Comparisons are made with measurements and other modeled results for a number of species. [Work supported by ONR.

22 CFR 1102.7 - The Section's determination and appeal procedures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true The Section's determination and appeal procedures. 1102.7 Section 1102.7 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.7 The Section's determination and appeal procedures. Upon receipt of any reques...

Temperature Reconstruction and Biomarker Variation across the Cretaceous-Paleogene Boundary, Mid-Waipara River, New Zealand

NASA Astrophysics Data System (ADS)

Taylor, K. W.; Hollis, C. J.; Pancost, R. D.

2010-12-01

The Cretaceous-Paleogene (K/Pg) boundary marks a catastrophic global extinction event, believed to be caused by an asteroid impact in northern Yucatan. Whilst the extent of mass extinction is well documented, there is ongoing debate about the immediate and longer term climatic and environmental changes triggered by the event. The northern South Island of New Zealand has several records of the K/Pg boundary, representing a range of terrestrial and marine environments. Previous studies of terrestrial palynomorphs and siliceous microfossils from these sections suggested significant cooling and terrestrial vegetation reconfiguration in the earliest Paleocene. Extinctions or local disappearances of thermophilic taxa at the K/Pg boundary are consistent with the hypothesis of a short-lived “impact winter”. The Mid-Waipara K/Pg boundary section, north Canterbury, has been identified as suitable for organic geochemical study because sufficient organic carbon is present in the siliciclastic sediments and is thermally immature. Sediments were deposited in outer shelf to upper slope depths under a neritic watermass. New estimates of sea surface temperature variation based on TEX86 elucidate the relationship between biological and climatic changes that followed the K/Pg event. Within the 0.25 m-thick interval identified as the “fern spike” in basal Paleocene sediments in this section there is no indication of a significant change in temperature relative to the Cretaceous (22-25°C). Foraminiferal and radiolarian biostratigraphy indicates that this interval spans ~100 kyrs and includes a fern succession from colonising ground ferns to tree ferns, the latter suggesting a temperate, humid climate. The transition from ferns to a conifer-dominated pollen assemblage corresponds with a remarkable decrease in temperature recorded in the TEX86 record. These cool temperatures persist over 10 m. The dominant conifer pollen type over this interval is Phyllocladites mawsonii, indicative of cool-temperate conditions. Preliminary biostratigraphic correlation suggests that this interval is condensed, possibly truncated at the base, and may be correlated to a more expanded biogenic silica-rich interval in the pelagic K/Pg boundary sections in eastern Marlborough, northeastern South Island. These results support siliceous microfossil evidence for pronounced cooling in early Paleocene in New Zealand. Organic biomarker records provide further insight into terrestrial and marine ecological reconfiguration through the K/Pg boundary transition at Mid-Waipara River. Major reorganisations of the phytoplankton and archaeal communities are indicated by pronounced changes in sterol and tetraether distributions following the K/Pg boundary. Transient disruption of higher plants at the boundary is verified by suppression of n-alkane and triterpenoid biomarker concentrations, succeeded by a gradual recovery into the Early Paleocene. The scenario envisaged may be summarised as climate instability following the K/Pg boundary event, culminating in cool climatic conditions and a strengthened local upwelling regime leading to widespread deposition of diatom-rich siliceous sediments, lasting for around 1 Myr.

Boundary Layer Structure and Its Relation to Precipitation Over the St. Louis Area.

DTIC Science & Technology

1980-10-01

of METEORO LOGY SECTION 0i{1J ( 0I~) AT THE mp UNI VERSITY OV ILLINOIS0 SMISContract Report 241 T - BOUNDARY LAYER STRUCTURE AND ITS RELATION TO...PRECIPITATION OVER THE ST. LOUIS AREA Gary L. Achtemeier Meteorology Section Ill1inois State Water &uIvey, DTII CLeELEC T E C.> JAN 15 1981( Technical...in f r ’TNil PA&F rlhImm Does Rnteredl 𔄃. -. , .’.-..,. -.- -/" . ECumITYv CLASSFICATIOW Of TH t PAGE(Wfhn Date Entr,.e) 15529. 4-GS ?0. ABSTRACT

Separable Ernst-Shakin-Thaler expansions of local potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bund, G.W.

The boundary condition Ernst-Shakin-Thaler method, introduced previously to generate separable expansions of local potentials of finite range, is applied to the study of the triplet s-wave Malfliet-Tjon potential. The effect of varying the radius where the boundary condition is applied on the T matrix is analyzed. Further, we compare the convergence of the n-d scattering cross sections in the quartet state below the breakup threshold for expansions corresponding to two different boundaries.

The Cretaceous-Tertiary (K/T) impact: One or more source craters?

NASA Technical Reports Server (NTRS)

Koeberl, Christian

1992-01-01

The Cretaceous-Tertiary (K/T) boundary is marked by signs of a worldwide catastrophe, marking the demise of more than 50 percent of all living species. Ever since Alvarez et al. found an enrichment of IR and other siderophile elements in rocks marking the K/T boundary and interpreted it as the mark of a giant asteroid (or comet) impact, scientists have tried to understand the complexities of the K/T boundary event. The impact theory received a critical boost by the discovery of shocked minerals that have so far been found only in association with impact craters. One of the problems of the K/T impact theory was, and still is, the lack of an adequate large crater that is close to the maximum abundance of shocked grains in K/T boundary sections, which was found to occur in sections in Northern America. The recent discovery of impact glasses from a K/T section in Haiti has been crucial in establishing a connection with documented impact processes. The location of the impact-glass findings and the continental nature of detritus found in all K/T sections supports at least one impact site near the North American continent. The Manson Impact Structure is the largest recognized in the United States, 35 km in diameter, and has a radiometric age indistinguishable from that of the Cretaceous-Tertiary (K/T) boundary. Although the Manson structure may be too small, it may be considered at least one element of the events that led to the catastrophic loss of life and extinction of many species at that time. A second candidate for the K/T boundary crater is the Chicxulub structure, which was first suggested to be an impact crater more than a decade ago. Only recently, geophysical studies and petrological (as well as limited chemical) analyses have indicated that this buried structure may in fact be of impact origin. At present we can conclude that the Manson crater is the only confirmed crater of K/T age, but Chicxulub is becoming a strong contender; however, detailed geochemical, geochronological, and isotopic data are necessary to provide definitive evidence.

The Cretaceous-Tertiary (K/T) impact: One or more source craters?

NASA Astrophysics Data System (ADS)

Koeberl, Christian

The Cretaceous-Tertiary (K/T) boundary is marked by signs of a worldwide catastrophe, marking the demise of more than 50 percent of all living species. Ever since Alvarez et al. found an enrichment of IR and other siderophile elements in rocks marking the K/T boundary and interpreted it as the mark of a giant asteroid (or comet) impact, scientists have tried to understand the complexities of the K/T boundary event. The impact theory received a critical boost by the discovery of shocked minerals that have so far been found only in association with impact craters. One of the problems of the K/T impact theory was, and still is, the lack of an adequate large crater that is close to the maximum abundance of shocked grains in K/T boundary sections, which was found to occur in sections in Northern America. The recent discovery of impact glasses from a K/T section in Haiti has been crucial in establishing a connection with documented impact processes. The location of the impact-glass findings and the continental nature of detritus found in all K/T sections supports at least one impact site near the North American continent. The Manson Impact Structure is the largest recognized in the United States, 35 km in diameter, and has a radiometric age indistinguishable from that of the Cretaceous-Tertiary (K/T) boundary. Although the Manson structure may be too small, it may be considered at least one element of the events that led to the catastrophic loss of life and extinction of many species at that time. A second candidate for the K/T boundary crater is the Chicxulub structure, which was first suggested to be an impact crater more than a decade ago. Only recently, geophysical studies and petrological (as well as limited chemical) analyses have indicated that this buried structure may in fact be of impact origin. At present we can conclude that the Manson crater is the only confirmed crater of K/T age, but Chicxulub is becoming a strong contender; however, detailed geochemical, geochronological, and isotopic data are necessary to provide definitive evidence.

27 CFR 9.98 - Monterey.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Monterey. 9.98 Section 9.98 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE... western boundary of the Cienega del Gabilan Land Grant and the eastern boundary of the El Alisal Land...

27 CFR 9.98 - Monterey.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Monterey. 9.98 Section 9.98 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE... western boundary of the Cienega del Gabilan Land Grant and the eastern boundary of the El Alisal Land...

7 CFR 25.101 - Data utilized for eligibility determinations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 1 2014-01-01 2014-01-01 false Data utilized for eligibility determinations. 25.101 Section 25.101 Agriculture Office of the Secretary of Agriculture RURAL EMPOWERMENT ZONES AND ENTERPRISE... statistics on boundaries. The boundary of a rural area nominated for designation as an Empowerment Zone or...

7 CFR 25.101 - Data utilized for eligibility determinations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 1 2012-01-01 2012-01-01 false Data utilized for eligibility determinations. 25.101 Section 25.101 Agriculture Office of the Secretary of Agriculture RURAL EMPOWERMENT ZONES AND ENTERPRISE... statistics on boundaries. The boundary of a rural area nominated for designation as an Empowerment Zone or...

7 CFR 25.101 - Data utilized for eligibility determinations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 1 2013-01-01 2013-01-01 false Data utilized for eligibility determinations. 25.101 Section 25.101 Agriculture Office of the Secretary of Agriculture RURAL EMPOWERMENT ZONES AND ENTERPRISE... statistics on boundaries. The boundary of a rural area nominated for designation as an Empowerment Zone or...

36 CFR 261.19 - Boundary Waters Canoe Area Wilderness.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Boundary Waters Canoe Area Wilderness. 261.19 Section 261.19 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF... or other mechanical device capable of propelling a watercraft through water by any means, except by...

36 CFR 261.19 - Boundary Waters Canoe Area Wilderness.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Boundary Waters Canoe Area Wilderness. 261.19 Section 261.19 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF... or other mechanical device capable of propelling a watercraft through water by any means, except by...

14 CFR 420.21 - Launch site location review-launch site boundary.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Launch site location review-launch site boundary. 420.21 Section 420.21 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... the debris dispersion radius of the largest launch vehicle type and weight class proposed for the...

14 CFR 420.21 - Launch site location review-launch site boundary.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Launch site location review-launch site boundary. 420.21 Section 420.21 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... the debris dispersion radius of the largest launch vehicle type and weight class proposed for the...

14 CFR 420.21 - Launch site location review-launch site boundary.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Launch site location review-launch site boundary. 420.21 Section 420.21 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... the debris dispersion radius of the largest launch vehicle type and weight class proposed for the...

27 CFR 9.207 - Outer Coastal Plain.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Outer Coastal Plain. (a) Name. The name of the viticultural area described in this section is “Outer...,000 scale. (c) Boundary. The Outer Coastal Plain viticultural area includes all of Cumberland, Cape... Counties in the State of New Jersey. The boundary of the Outer Coastal Plain viticultural area is as...

77 FR 38035 - Boundary Establishment for the Allegheny National Wild and Scenic River, Allegheny National...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-26

... DEPARTMENT OF AGRICULTURE Forest Service Boundary Establishment for the Allegheny National Wild... Section 3(b) of the Wild and Scenic Rivers Act, the USDA Forest Service, Allegheny National Forest... Allegheny National Wild and Scenic River. This document was published before sufficient consultation with...

49 CFR 372.239 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... pursuant to general State laws, or which is recognized as such, under the Constitution or by the laws of... (a) of this section, which have at some point a common municipal or corporate boundary. (c) Unincorporated area means any area not within the corporate or municipal boundaries of any municipality as...

Interfacing the NRL 1-D High Vertical Resolution Aerosol Model with COAMPS

DTIC Science & Technology

2006-09-30

model integrated with mesoscale meterological data to study marine boundary layer aerosol dynamics, J. Geophys. Res., in press, 2006. Hoppel, W. A...W.A. Hoppel, J.J. Shi: A one-dimensional sectional aerosol model integrated with mesoscale meterological data to study marine boundary layer aerosol

14 CFR 420.21 - Launch site location review-launch site boundary.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Launch site location review-launch site boundary. 420.21 Section 420.21 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... the debris dispersion radius of the largest launch vehicle type and weight class proposed for the...

14 CFR 420.21 - Launch site location review-launch site boundary.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Launch site location review-launch site boundary. 420.21 Section 420.21 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... the debris dispersion radius of the largest launch vehicle type and weight class proposed for the...

7 CFR 25.101 - Data utilized for eligibility determinations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 1 2010-01-01 2010-01-01 false Data utilized for eligibility determinations. 25.101 Section 25.101 Agriculture Office of the Secretary of Agriculture RURAL EMPOWERMENT ZONES AND ENTERPRISE... statistics on boundaries. The boundary of a rural area nominated for designation as an Empowerment Zone or...

7 CFR 25.101 - Data utilized for eligibility determinations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 1 2011-01-01 2011-01-01 false Data utilized for eligibility determinations. 25.101 Section 25.101 Agriculture Office of the Secretary of Agriculture RURAL EMPOWERMENT ZONES AND ENTERPRISE... statistics on boundaries. The boundary of a rural area nominated for designation as an Empowerment Zone or...

22 CFR 1104.11 - Relationship to section 106 of the National Historic Preservation Act.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Relationship to section 106 of the National Historic Preservation Act. 1104.11 Section 1104.11 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.11...

22 CFR 1104.11 - Relationship to section 106 of the National Historic Preservation Act.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Relationship to section 106 of the National Historic Preservation Act. 1104.11 Section 1104.11 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.11...

Perception of hierarchical boundaries in music and its modulation by expertise.

PubMed

Zhang, Jingjing; Jiang, Cunmei; Zhou, Linshu; Yang, Yufang

2016-10-01

Hierarchical structure with units of different timescales is a key feature of music. For the perception of such structures, the detection of each boundary is crucial. Here, using electroencephalography (EEG), we explore the perception of hierarchical boundaries in music, and test whether musical expertise modifies such processing. Musicians and non-musicians were presented with musical excerpts containing boundaries at three hierarchical levels, including section, phrase and period boundaries. Non-boundary was chosen as a baseline condition. Recordings from musicians showed CPS (closure positive shift) was evoked at all the three boundaries, and their amplitude increased as the hierarchical level became higher, which suggest that musicians could represent music events at different timescales in a hierarchical way. For non-musicians, the CPS was only elicited at the period boundary and undistinguishable negativities were induced at all the three boundaries. The results indicate that a different and less clear way was used by non-musicians in boundary perception. Our findings reveal, for the first time, an ERP correlate of perceiving hierarchical boundaries in music, and show that the phrasing ability could be enhanced by musical expertise. Copyright © 2016 Elsevier Ltd. All rights reserved.

Semiconductor P-I-N detector

DOEpatents

Sudharsanan, Rengarajan; Karam, Nasser H.

2001-01-01

A semiconductor P-I-N detector including an intrinsic wafer, a P-doped layer, an N-doped layer, and a boundary layer for reducing the diffusion of dopants into the intrinsic wafer. The boundary layer is positioned between one of the doped regions and the intrinsic wafer. The intrinsic wafer can be composed of CdZnTe or CdTe, the P-doped layer can be composed of ZnTe doped with copper, and the N-doped layer can be composed of CdS doped with indium. The boundary layers is formed of an undoped semiconductor material. The boundary layer can be deposited onto the underlying intrinsic wafer. The doped regions are then typically formed by a deposition process or by doping a section of the deposited boundary layer.

Astronomical tuning and carbon isotope stratigraphy of the Maastrichtian in Sopelana and Zumaia (Basque country, N-Spain)

NASA Astrophysics Data System (ADS)

Batenburg, S. J.; Gale, A. S.; Hilgen, F. J.; Hüsing, S. K.; Laskar, J.; Orue-Etxebarria, X.; Sprovieri, M.; Voigt, S.

2012-04-01

Astronomical tuning has led to significant refinement of the Geological Time Scale for the Cenozoic, however the Late Cretaceous time scale still has potential errors of ~0.5 Myr. The Basque sections of Sopelana and Zumaia (N-Spain) provide a high-resolution sedimentary archive encompassing the Maastrichtian up to the Cretaceous/Paleogene boundary. Rhythmic limestone-marl alternations, deposited in a hemipelagic setting, reflect the influence of the periodicities of eccentricity modulated precession. Starting from a K/Pg boundary age of 66.0 Ma, consecutive 405-kyr minima are tuned to the new astronomical solution La2011. This orbital tuning, together with the expression of individual precessional cycles, allows for unprecedented refinement of the Geologic Time Scale for the Maastrichtian with errors <100 kyr. The cyclostratigraphic interpretation is thoroughly tested by time series analysis of magnetic susceptibility and colour reflectance data. A cyclostratigraphic framework and orbital tuning of the Zumaia section has recently been obtained. This is extended further back in time by correlation to the Sopelana section by recognition of orbital patterns and marker beds. The total amount of time represented by the two sections is 5 Myr. The lower boundary falls within chron C32N1n, almost reaching the Campanian/Maastrichtian boundary. Magnetostratigraphic and biostratigraphic data allow for application of the cyclostratigraphic framework worldwide, and comparison to previously published Maastrichtian time scales. Additionally, we present an orbitally tuned bulk carbon isotope curve. The high resolution and large amplitude of shifts in δ13C on the 405-kyr and 1.2-Myr scales enables correlation to deep marine oceanic sites, several sections from the Boreal chalk sea and Italy and, importantly, the Campanian/Maastrichtian boundary GSSP at Tercis, France. This will provide a globally applicable cyclostratigraphic framework for the entire Maastrichtian. We will discuss the implications for the orbital pacing theory of the late Cretaceous climate system. Furthermore we will elaborate on the enigmatic presence of a strong 1.2-Myr cyclicity in lithological and proxy record data and its possible relation to carbon cycle dynamics and/or orbital forcing.

27 CFR 9.218 - Sierra Pelona Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

... north across a trail and an unimproved dirt road, to the line's intersection with the section 21 south... National Forest boundary line, an unnamed stream running through Rowher Canyon, and the section 17 south...

Molluscan extinction patterns across the Cenomanian-Turonian stage boundary in the western interior of the United States

USGS Publications Warehouse

Elder, W.P.

1989-01-01

High-resolution stratigraphic analysis of 18 sections spanning the Cenomanian-Turonian Stage boundary in the western interior of the United States has allowed determination of the magnitude and pattern of molluscan extinction and disruption. Composite range data from all sections show that the faunal turnover across the stage boundary occurs in a series of narrow stratigraphic zones, defined by multiple first and last occurrences, separated by intervals displaying little or no taxonomic turnover. Two of the apparent extinction steps (bottom and top of the Neocardioceras juddii Zone) may be intercontinentally developed. The additional steps apparently reflect cyclic changes in water mass and substrate characteristics in the western interior basin produced in response to orbital forcing of climate. The most affected mollusks were those having intercontinental distributions. -Author

Flowfield measurements in the NASA Lewis Research Center 9- by 15-foot low-speed wind tunnel

NASA Technical Reports Server (NTRS)

Hughes, Christopher E.

1989-01-01

An experimental investigation was conducted in the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel to determine the flow characteristics in the test section during wind tunnel operation. In the investigation, a 20-probe horizontally-mounted Pitot-static flow survey rake was used to obtain cross-sectional total and static pressure surveys at four axial locations in the test section. At each axial location, the cross-sectional flowfield surveys were made by repositioning the Pitot-static flow survey rake vertically. In addition, a calibration of the new wind tunnel rake instrumentation, used to determine the wind tunnel operating conditions, was performed. Boundary laser surveys were made at three axial locations in the test section. The investigation was conducted at tunnel Mach numbers 0.20, 0.15, 0.10, and 0.05. The test section profile results from the investigation indicate that fairly uniform total pressure profiles (outside the test section boundary layer) and fairly uniform static pressure and Mach number profiles (away from the test section walls and downstream of the test section entrance) exist throughout in the wind tunnel test section.

Benthic foraminifera at the Cretaceous-Tertiary boundary around the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Alegret, Laia; Molina, Eustoquio; Thomas, Ellen

2001-10-01

Cretaceous-Tertiary (K-T) boundary sections in northeastern Mexico contain marly formations separated by a controversial clastic unit. Benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls, with the exception of the upper bathyal northernmost section. Mixed neritic-bathyal faunas were present in the clastic unit, indicating redeposition in the deep basin by mass-wasting processes resulting from the K-T bolide impact in the Gulf of Mexico. Benthic foraminifera in the Mexican sections, and at other deep-sea locations, were not subject to major extinction at the time of impact, but there were temporary changes in assemblage composition. Benthic faunas indicate well- oxygenated bottom waters and mesotrophic conditions during the late Maastrichtian and increased food supply during the latest Maastrichtian. The food supply decreased drastically just after the K-T boundary, possibly because of the collapse of surface productivity. Cretaceous and early Paleogene benthic foraminifera, however, did not exhibit the benthic-pelagic coupling of present-day faunas, as documented by the lack of significant extinction at the K-T collapse of surface productivity. Much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions. The decrease in food supply at the K-T boundary might be associated with the processes of mass wasting, which removed surface, food-rich sediment. Benthic faunas show a staggered pattern of faunal recovery in the lowermost Paleogene, consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment.

Sequence stratigraphy of the Maastrichtian-Paleocene succession at the Dakhla Oasis, Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Hewaidy, Abdel Galil A.; Farouk, Sherif; Bazeen, Youssef S.

2017-12-01

The Maastrichtian-Paleocene succession at the Dakhla Oasis is marked by the presence of a typical Nile Valley Facies represented by the Dakhla and Tarawan formations in Edmonstone and Qur El Malik sections in the central and western parts of the oasis, while a mixed Nile Valley and Garra Al-Arbain facies represented by Dakhla, Kurkur and Tarawan formations in Teneida section in the eastern part of the oasis adjacent to the Abu Tartur Plateau. These sections were examined for their foraminiferal contents, lithologic characters and stratigraphic boundaries. The distribution of foraminifera in the studied sections is variable and inconstant, as the planktonics are concentrated only at certain levels, which may be considered as a time intervals of transgression and maximum flooding surfaces. Eight planktonic biozones are distinguished in this work; of theses two are of Maastrichtain age and six are of Paleocene age. Eight 3rd order depositional sequences are recognized in the studied Maastrichtian-Paleocene succession based on the time stratigraphic boundaries released from the planktonic foraminifera and sea level changes which are released from the paleoecologic interpretations. The distinguished sequences are subdivided into their systems tracts based on the paleobathymetric interpretations of P/B% and benthic biofacies analysis. These sequences are bounded by eight sequence boundaries (SB A - SB H) represented by unconformity surfaces and depositional hiatuses. The correlation of the sequence boundaries of the established depositional sequences with the eustatic sea level curve, suggesting that these depositional sequences were resulted from the interplay of eustatic sea-level changes and local tectonic activities.

Residual interference and wind tunnel wall adaption

NASA Technical Reports Server (NTRS)

Mokry, Miroslav

1989-01-01

Measured flow variables near the test section boundaries, used to guide adjustments of the walls in adaptive wind tunnels, can also be used to quantify the residual interference. Because of a finite number of wall control devices (jacks, plenum compartments), the finite test section length, and the approximation character of adaptation algorithms, the unconfined flow conditions are not expected to be precisely attained even in the fully adapted stage. The procedures for the evaluation of residual wall interference are essentially the same as those used for assessing the correction in conventional, non-adaptive wind tunnels. Depending upon the number of flow variables utilized, one can speak of one- or two-variable methods; in two dimensions also of Schwarz- or Cauchy-type methods. The one-variable methods use the measured static pressure and normal velocity at the test section boundary, but do not require any model representation. This is clearly of an advantage for adaptive wall test section, which are often relatively small with respect to the test model, and for the variety of complex flows commonly encountered in wind tunnel testing. For test sections with flexible walls the normal component of velocity is given by the shape of the wall, adjusted for the displacement effect of its boundary layer. For ventilated test section walls it has to be measured by the Calspan pipes, laser Doppler velocimetry, or other appropriate techniques. The interface discontinuity method, also described, is a genuine residual interference assessment technique. It is specific to adaptive wall wind tunnels, where the computation results for the fictitious flow in the exterior of the test section are provided.

Geographic boundary of the “Pacific Anomaly” near the Earth’s core-mantle boundary

NASA Astrophysics Data System (ADS)

He, Y.; Wen, L.

2009-12-01

Seismic tomography have revealed a broad, seismically low velocity anomaly in the Earth’s lower mantle beneath the Pacific (we term it the “Pacific Anomaly”), surrounded by the circum-Pacific high velocity zone. Here, we determine geographical boundary and average shear velocity structure of the Pacific Anomaly near the core-mantle boundary based on travel time analysis of ScSH-SH and ScS2-SS phases. We further constrain the detailed structure of the transition from the base of the Pacific Anomaly to the northern high velocity zone along two perpendicular cross sections on the basis of forward waveform modeling of the seismic data. Two cross-sections include one great arc across the Anomaly from New Zealand to Alaska and another from Solomon Islands to North America. Our seismic data are collected from those recorded in the China National Digital Seismographic Network, and many permanent and temporal arrays from the Incorporated Research Institutions for Seismology. The observed ScS-SH and ScS2-SS differential travel time residuals allow the entire geographic boundary of the anomaly to be clearly defined. The seismic data suggest that the average shear velocity reduction inside the anomaly reaches -5% in the lowermost 300 km of the mantle. Waveform analysis of the seismic data sampling the edge of the anomaly further validates the model of the boundary previously deduced by differential-travel-time-residual data, and suggests that the northern boundary is characterized by a shear velocity model with the low-velocity region accompanied by a high velocity structure.

Application of the Boundary Element Method to Fatigue Crack Growth Analysis

DTIC Science & Technology

1988-09-01

III, and Noetic PROBE in Section IV. Correlation of the boundary element method and modeling techniques employed in this study were shown with the...distribution unlimited I I I Preface! 3 The purpose of this study was to apply the boundary element method (BEM) to two dimensional fracture mechanics...problems, and to use the BEM to analyze the interference effects of holes on cracks through a parametric study of a two hole 3 tension strip. The study

22 CFR 1104.16 - Other penalties and rewards.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Other penalties and rewards. 1104.16 Section 1104.16 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.16 Other penalties and rewards. (a) Section...

22 CFR 1104.16 - Other penalties and rewards.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Other penalties and rewards. 1104.16 Section 1104.16 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.16 Other penalties and rewards. (a) Section...

Palynologically calibrated vertebrate record from North Dakota consistent with abrupt dinosaur extinction at the Cretaceous-Tertiary boundary

USGS Publications Warehouse

Pearson, D.A.; Schaefer, T.; Johnson, K.R.; Nichols, D.J.

2001-01-01

New data from 17 Cretaceous-Tertiary (K-T) boundary sections and 53 vertebrate sites in the Hell Creek and Fort Union Formations in southwestern North Dakota document a 1.76 m barren interval between the highest Cretaceous vertebrate fossils and the palynologically recognized K-T boundary. The boundary is above the formational contact at 15 localities and coincident with it at two, demonstrating that the formational contact is diachronous. Dinosaurs are common in the highest Cretaceous vertebrate samples and a partial dinosaur skeleton in the Fort Union Formation is the highest recorded Cretaceous vertebrate fossil in this area.

Separated flows receptivity for external disturbances

NASA Astrophysics Data System (ADS)

Zanin, B. Yu.

2017-10-01

Results of experimental investigations of the flow over a straight-wing model in a low-turbulence wind tunnel are reported. The influence of a turbulent wake due to a thin filament on the structure of boundary layer on the model surface was examined. Also the fishing line was installed in the test section of the wind tunnel and the effect of line on the boundary-layer flow structure is considered. Flow visualization in boundary layer and hot-wire measurements were performed. The wake and the grid substantially modified the boundary layer flow pattern: the separation disappeared from the wing surface, and the formation of longitudinal structures was observed.

Reduction of acoustic disturbances in the test section of supersonic wind tunnels by laminarizing their nozzle and test section wall boundary layers by means of suction

NASA Technical Reports Server (NTRS)

Pfenninger, W.; Syberg, J.

1974-01-01

The feasibility of quiet, suction laminarized, high Reynolds number (Re) supersonic wind tunnel nozzles was studied. According to nozzle wall boundary layer development and stability studies, relatively weak area suction can prevent amplified nozzle wall TS (Tollmien-Schlichting) boundary layer oscillations. Stronger suction is needed in and shortly upstream of the supersonic concave curvature nozzle area to avoid transition due to amplified TG (Taylor-Goertler) vortices. To control TG instability, moderately rapid and slow expansion nozzles require smaller total suction rates than rapid expansion nozzles, at the cost of larger nozzle length Re and increased TS disturbances. Test section mean flow irregularities can be minimized with suction through longitudinal or highly swept slots (swept behind local Mach cone) as well as finely perforated surfaces. Longitudinal slot suction is optimized when the suction-induced crossflow velocity increases linearly with surface distance from the slot attachment line toward the slot (through suitable slot geometry). Suction in supersonic blowdown tunnels may be operated by one or several individual vacuum spheres.

40 CFR 257.3-4 - Ground water.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an underground drinking water source beyond the solid waste boundary or beyond an alternative boundary specified in...

40 CFR 257.3-4 - Ground water.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an underground drinking water source beyond the solid waste boundary or beyond an alternative boundary specified in...

36 CFR 28.3 - Boundaries: The Community Development District; The Dune District; The Seashore District.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Boundaries: The Community Development District; The Dune District; The Seashore District. 28.3 Section 28.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR FIRE ISLAND NATIONAL SEASHORE: ZONING STANDARDS...

49 CFR 71.7 - Boundary line between central and mountain zones.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Boundary line between central and mountain zones. 71.7 Section 71.7 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE... mountain standard time zone, except Murdo, S. Dak., which is in the central standard time zone. [Amdt. 71...

40 CFR 257.3-4 - Ground water.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an underground drinking water source beyond the solid waste boundary or beyond an alternative boundary specified in...

40 CFR 257.3-4 - Ground water.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an underground drinking water source beyond the solid waste boundary or beyond an alternative boundary specified in...

40 CFR 257.3-4 - Ground water.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an underground drinking water source beyond the solid waste boundary or beyond an alternative boundary specified in...

36 CFR 28.3 - Boundaries: The Community Development District; The Dune District; The Seashore District.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Boundaries: The Community Development District; The Dune District; The Seashore District. 28.3 Section 28.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR FIRE ISLAND NATIONAL SEASHORE: ZONING STANDARDS...

77 FR 21522 - Boundary Establishment for the Allegheny National Wild and Scenic River, Allegheny National...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-10

... Venango Counties, PA AGENCY: Forest Service, USDA. ACTION: Notice of availability. SUMMARY: In accordance with Section 3(b) of the Wild and Scenic Rivers Act, the USDA Forest Service, Washington Office, is... Allegheny Wild and Scenic River boundary is available for review at the following offices: USDA Forest...

Flight Measurement of Wall-Pressure Fluctuations and Boundary-Layer Turbulence

NASA Technical Reports Server (NTRS)

Mull, Harold R.; Algranti, Joseph S.

1960-01-01

The results are presented for a flight test program using a fighter type jet aircraft flying at pressure altitudes of 10,000, 20,000, and 30,000 feet at Mach numbers from 0.3 to 0.8. Specially designed apparatus was used to measure and record the output of microphones and hot-wire anemometers mounted on the forward-fuselage section and wing of the airplane. Mean-velocity profiles in the boundary layers were obtained from total-pressure measurements. The ratio of the root-mean-square fluctuating wall pressure to the free-stream dynamic pressure is presented as a function of Reynolds number and Mach number. The longitudinal component of the turbulent-velocity fluctuations was measured, and the turbulence-intensity profiles are presented for the wing and forward-fuselage section. In general, the results are in agreement with wind-tunnel measurements which have been-reported in the literature. For example, the variation the square root of p(sup 2)/q times the square root of p(sup 2) is the root mean square of the wall-pressure fluctuation, and q is the free-stream dynamic pressure) with Reynolds number was found to be essentially constant for the forward-fuselage-section boundary layer, while variations at the wing station were probably unduly affected by the microphone diameter (5/8 in.), which was large compared with the boundary-layer thickness.

Mach Number effects on turbulent superstructures in wall bounded flows

NASA Astrophysics Data System (ADS)

Kaehler, Christian J.; Bross, Matthew; Scharnowski, Sven

2017-11-01

Planer and three-dimensional flow field measurements along a flat plat boundary layer in the Trisonic Wind Tunnel Munich (TWM) are examined with the aim to characterize the scaling, spatial organization, and topology of large scale turbulent superstructures in compressible flow. This facility is ideal for this investigation as the ratio of boundary layer thickness to test section spanwise extent ratio is around 1/25, ensuring minimal sidewall and corner effects on turbulent structures in the center of the test section. A major difficulty in the experimental investigation of large scale features is the mutual size of the superstructures which can extend over many boundary layer thicknesses. Using multiple PIV systems, it was possible to capture the full spatial extent of large-scale structures over a range of Mach numbers from Ma = 0.3 - 3. To calculate the average large-scale structure length and spacing, the acquired vector fields were analyzed by statistical multi-point methods that show large scale structures with a correlation length of around 10 boundary layer thicknesses over the range of Mach numbers investigated. Furthermore, the average spacing between high and low momentum structures is on the order of a boundary layer thicknesses. This work is supported by the Priority Programme SPP 1881 Turbulent Superstructures of the Deutsche Forschungsgemeinschaft.

Geochemistry of pyrite from diamictites of the Hamersley Basin, Western Australia with implications for the GOE and Paleoproterozoic ice ages.

NASA Astrophysics Data System (ADS)

Swanner, Elizabeth; Cates, Nicole; Pecoits, Ernesto; Bekker, Andrey; Konhauser, Kurt O.; Mojzsis, Stephen J.

2013-04-01

Sediments of the ca. 2400 Ma Turee Creek Group of Western Australia span the oxygenation of Earth's surface resulting from the 'Great Oxidation Event' (GOE). Diamictite within the Boolgeeda Iron Formation from the Boundary Ridge section at Duck Creek Syncline have been correlated to the glaciogenic Meteorite Bore Member of the Turee Creek Group at Hardey Syncline (Martin, 1999). The Meteorite Bore Member is thought to be correlative and time-equivalent with the Paleoproterozoic glacial diamictites of North America. If diamictite units at Boundary Ridge represent worldwide Paleoproterozoic glaciations, they should record the disappearance of mass independently fractionated (MIF) sulfur. Triple S-isotope compositions for pyrites from the Boundary Ridge sections measured by in situ multi-collector ion microprobe yielded both mass-dependent and mass-independently fractionated (MIF) S isotope values (Δ33S values from -0.65 to 6.27). Trace element heterogeneities were found by measurements at multiple spatial scales within rounded pyrites in the Boundary Ridge section, signifying multiple generations of pyrite from sulfur processed in an anoxic atmosphere. S-isotope data from pyrite in the Boundary Ridge diamictites analyzed in this study and previous work (Williford et al., 2011) define multiple δ34S vs. δ33S arrays, linked to a source of detrital pyrite from the overlying Hamersley and Fortescue groups. Authigenic pyrite in an overlying shale unit from Boundary Ridge plot along the terrestrial fractionation line but retain positive MIF-S and detrital pyrite, results that are incompatible with a correlation to North American Paleoproterozoic glacially-influenced successions where the MIF-S signal permanently disappears. The diamictites at the Duck Creek Syncline are older than the Meteorite Bore Member because of their stratigraphic position within the Boolgeeda Iron Formation underlying the Turee Creek Group, which is separated from the Meteorite Bore Member by nearly 1000 m of Kungarra shale at Hardey Syncline.

Mise en oeuvre et etalonnage d'une soufflerie de recherche sur les couches limites

NASA Astrophysics Data System (ADS)

Pioton, Julien

In order to reproduce a turbulent boundary layer separation bubble in a laboratory at the École de Technologie Supérieure of Montreal, an open-circuit wind tunnel equipped with a blow-down centrifugal fan has been implemented and calibrated for this research project. The methodology for the conception of the wind tunnel components, based on the results obtained from previous experiments, has been validated by the comparison between experimental and theoretical pressure losses along the wind tunnel. Dimensionless mean axial velocity measurements in the working section have showed an irrotational uniform flow zone at the contraction end, which demonstrates the satisfactory performance of the flowconditioning components located upstream from the working section. Mean axial velocity and total pressure measurements along the working section have allowed for estimates of the location of boundary between irrotational and rotational flow at the separation bubble. The maximum mean height of the boundary layer has been estimated at around 15 cm. Oil film visualisations have revealed a mean bubble separation length of approximately 52 cm. Theses oil visualisations, supported by mean lateral velocity measurements in the current configuration of the working section, have indicated important three-dimensional effects and significant dissymmetry in the vicinity of the separation and reattachment zones at the separation bubble.

An investigation of the effects of the propeller slipstream of a laminar wing boundary layer

NASA Technical Reports Server (NTRS)

Howard, R. M.; Miley, S. J.; Holmes, B. J.

1985-01-01

A research program is in progress to study the effects of the propeller slipstream on natural laminar flow. Flight and wind tunnel measurements of the wing boundary layer have been made using hot-film velocity sensor probes. The results show the boundary layer, at any given point, to alternate between laminar and turbulent states. This cyclic behavior is due to periodic external flow turbulence originating from the viscous wake of the propeller blades. Analytic studies show the cyclic laminar/turbulent boundary layer to result in a significantly lower wing section drag than a fully turbulent boundary layer. The application of natural laminar flow design philosophy yields drag reduction benefits in the slipstream affected regions of the airframe, as well as the unaffected regions.

Features of bicrystal growth during the directional crystallization of metal melts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gubernatorov, V. V.; Sycheva, T. S., E-mail: sych@imp.uran.ru; Gundyrev, V. M.

2017-03-15

The factors responsible for the formation of different configurations of boundaries between adjacent crystallites during their growth from melt by Bridgman and Czochralski methods have been considered by an of example Fe–20 wt % Ga alloy and Ni bicrystals. It is found that the configuration of intercrystallite boundary is related to the features of crystallite growth, caused by the strained state of intercrystallite and interphase (crystal–melt) boundaries, the difference in the linear thermal expansion coefficients of the crystallite boundaries and bulk, and the shape (geometry) of the bicrystal cross section. It is suggested that the strained state of boundaries andmore » the formation of substructure in crystallites during directional crystallization from metal melt are significantly affected by their deformation under the melt weight.« less

Experimental measurements of unsteady turbulent boundary layers near separation

NASA Technical Reports Server (NTRS)

Simpson, R. L.

1982-01-01

Investigations conducted to document the behavior of turbulent boundary layers on flat surfaces that separate due to adverse pressure gradients are reported. Laser and hot wire anemometers measured turbulence and flow structure of a steady free stream separating turbulent boundary layer produced on the flow of a wind tunnel section. The effects of sinusoidal and unsteadiness of the free stream velocity on this separating turbulent boundary layer at a reduced frequency were determined. A friction gage and a thermal tuft were developed and used to measure the surface skin friction and the near wall fraction of time the flow moves downstream for several cases. Abstracts are provided of several articles which discuss the effects of the periodic free stream unsteadiness on the structure or separating turbulent boundary layers.

Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus(Trademark) Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Garg, Anita; Lin, Peter; Provenzano, virgil; Heard, Robert; Miller, Herbert M.

2010-01-01

Grain Boundary Engineering can enhance the population of structurally-ordered "low S" Coincidence Site Lattice (CSL) grain boundaries in the microstructure. In some alloys, these "special" grain boundaries have been reported to improve overall resistance to corrosion, oxidation, and creep resistance. Such improvements could be quite beneficial for superalloys, especially in conditions which encourage damage and cracking at grain boundaries. Therefore, the effects of GBE processing on high-temperature mechanical properties of the cast and wrought superalloy Allvac 718Plus (Allvac ATI) were screened. Bar sections were subjected to varied GBE processing, and then consistently heat treated, machined, and tested at 650 C. Creep, tensile stress relaxation, and dwell fatigue crack growth tests were performed. The influences of GBE processing on microstructure, mechanical properties, and associated failure modes are discussed.

Grain Boundary Evolution of Cold-Rolled FePd Alloy during Recrystallization at Disordering Temperature

PubMed Central

Lin, Hung-Pin; Chen, Delphic; Kuo, Jui-Chao

2015-01-01

In this study, the grain boundary character and texture of 50% and 90% cold-rolled FePd alloy was investigated during recrystallization at 700 °C. Electron backscatter diffraction (EBSD) measurements were performed on the rolling direction to normal direction section. Kernel average misorientation (KAM) calculated from EBSD measurements was employed to determine the recrystallization fraction. The Avrami exponent n of recrystallization is 1.9 and 4.9 for 50% and 90% cold rolling, respectively. The new formation of texture reveals random texture during the recrystallization process. As annealing time increased, the number of high angle boundary (HAGB) and coincidence site lattice (CSL) increased with consumption of low angle boundary (LAGB). In addition, possible transformations between different grain boundaries are observed here.

Partial Section Through Stack, Water Tank, and Privy; Plan ...

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

Partial Section Through Stack, Water Tank, and Privy; Plan - Stack, Privies, & Changing Rooms; Elevation - Central of Georgia Railway, Savannah Repair Shops & Terminal Facilities, Bounded by West Broad, Jones, West Boundary & Hull Streets, Savannah, Chatham County, GA

Morning view of the exterior of the westernmost wall section ...

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

Morning view of the exterior of the westernmost wall section to be removed; camera facing south. Unpaved road in foreground; tree canopy in background. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC

Depositional systems and stratigraphy of Paleozoic and Lower Mesozoic rocks in outcrop, Tassili region, southwest Algeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hertig, S.P.; Tye, R.S.; Coffield, D.Q.

1991-08-01

Paleozoic to Lower Mesozoic strata of the southeastern Algerian Tassili are traditionally subdivided by regionally extensive unconformities such as the Pan African, Taconic, Caledonian, and Hercynian. Using outcrop data from southeastern Algeria, this classic approach is modified by reinterpreting the genesis of these unconformities and rock sequences. Five prominent sequences, defined within the Paleozoic and lower Mesozoic section, usually consist of a succession of lowstand, transgressive, and highstand system tracts separated by sequence boundaries or transgressive surfaces. The Pan-African, Taconic, Caledonian, and Hercynian unconformities are sequence boundaries. Important sequence boundaries also occur within the Ordovician and Silurian sections. These sequencesmore » correlate with subsurface data in the Illizi basin and provide a framework for renewed exploration in the subsurface of the Algerian Sahara, where more than 30 billion bbl of recoverable oil and oil equivalent have been generated and trapped.« less

A study of the factors affecting boundary layer two-dimensionality in wind tunnels

NASA Technical Reports Server (NTRS)

Mehta, R. D.; Hoffmann, P. H.

1986-01-01

The effect of screens, honeycombs, and centrifugal blowers on the two-dimensionality of a boundary layer on the test section floors of low-speed blower tunnels is studied. Surveys of the spanwise variation in surface shear stress in three blower tunnels revealed that the main component responsible for altering the spanwise properties of the test section boundary layer was the last screen, thus confirming previous findings. It was further confirmed that a screen with varying open-area ratio, produced an unstable flow. However, contrary to popular belief, it was also found that for given incoming conditions and a screen free of imperfections, its open-area ratio alone was not enough to describe its performance. The effect of other geometric parameters such as the type of screen, honeycomb, and blower were investigated. In addition, the effect of the order of components in the settling chamber, and of wire Reynolds number were also studied.

F-8 supercritical wing flight pressure, Boundary layer, and wake measurements and comparisons with wind tunnel data

NASA Technical Reports Server (NTRS)

Montoya, L. C.; Banner, R. D.

1977-01-01

Data for speeds from Mach 0.50 to Mach 0.99 are presented for configurations with and without fuselage area-rule additions, with and without leading-edge vortex generators, and with and without boundary-layer trips on the wing. The wing pressure coefficients are tabulated. Comparisons between the airplane and model data show that higher second velocity peaks occurred on the airplane wing than on the model wing. The differences were attributed to wind tunnel wall interference effects that caused too much rear camber to be designed into the wing. Optimum flow conditions on the outboard wing section occurred at Mach 0.98 at an angle of attack near 4 deg. The measured differences in section drag with and without boundary-layer trips on the wing suggested that a region of laminar flow existed on the outboard wing without trips.

Definition and means of maintaining the supply ventilation system seismic shutdown portion of the PFP safety envelope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keck, R.D.

1997-01-21

The purpose of this document is to record the technical evaluation of the Limiting Condition for Operation (LCO) described in the Plutonium Finishing Plant (PFP) Operational Safety Requirements, WHC-SD-CP-OSR- 010, Rev. 0. Kay 1994, Section 3.2.3, `Supply Ventilation System Seismic Shutdown.` This document, with its appendices, provides the following: 1. The system functional requirements for determining system operability (Section 3). 2. Evaluations of equipment to determine the safety boundary for the system (Section 4). 3. A list of annotated drawings which show the safety envelope boundaries (Appendix C). 4. A list of the safety envelope equipment (Appendix B). 5. Functionalmore » requirements for the individual safety envelope equipment, including appropriate setpoints and process parameters (Section 4.1). 6. A list of the operational, maintenance and surveillance procedures necessary to operate and maintain the system equipment within the safety envelope (Sections 5 and 6 and Appendix A).« less

27 CFR 9.218 - Sierra Pelona Valley.

Code of Federal Regulations, 2013 CFR

2013-04-01

... line 0.15 mile, crossing over the Agua Dulce Road, to the line's intersection with the 2,400-foot... boundary line onto the Sleepy Valley map 0.6 mile to the line's intersection with the 2,800-foot elevation... the section 22 north boundary line 0.2 mile to the line's intersection with the 2,600-foot elevation...

27 CFR 9.218 - Sierra Pelona Valley.

Code of Federal Regulations, 2012 CFR

2012-04-01

... line 0.15 mile, crossing over the Agua Dulce Road, to the line's intersection with the 2,400-foot... boundary line onto the Sleepy Valley map 0.6 mile to the line's intersection with the 2,800-foot elevation... the section 22 north boundary line 0.2 mile to the line's intersection with the 2,600-foot elevation...

27 CFR 9.218 - Sierra Pelona Valley.

Code of Federal Regulations, 2014 CFR

2014-04-01

... line 0.15 mile, crossing over the Agua Dulce Road, to the line's intersection with the 2,400-foot... boundary line onto the Sleepy Valley map 0.6 mile to the line's intersection with the 2,800-foot elevation... the section 22 north boundary line 0.2 mile to the line's intersection with the 2,600-foot elevation...

19 CFR 122.23 - Certain aircraft arriving from areas south of the U.S.

Code of Federal Regulations, 2012 CFR

2012-04-01

... U.S. 122.23 Section 122.23 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... inner boundary of the Atlantic (Coastal) Air Defense Identification Zone (ADIZ) south of 30 degrees north latitude, anywhere outside of the inner boundary of the Gulf of Mexico (Coastal) ADIZ, or anywhere...

19 CFR 122.23 - Certain aircraft arriving from areas south of the U.S.

Code of Federal Regulations, 2011 CFR

2011-04-01

... U.S. 122.23 Section 122.23 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... inner boundary of the Atlantic (Coastal) Air Defense Identification Zone (ADIZ) south of 30 degrees north latitude, anywhere outside of the inner boundary of the Gulf of Mexico (Coastal) ADIZ, or anywhere...

19 CFR 122.23 - Certain aircraft arriving from areas south of the U.S.

Code of Federal Regulations, 2014 CFR

2014-04-01

... U.S. 122.23 Section 122.23 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... inner boundary of the Atlantic (Coastal) Air Defense Identification Zone (ADIZ) south of 30 degrees north latitude, anywhere outside of the inner boundary of the Gulf of Mexico (Coastal) ADIZ, or anywhere...

19 CFR 122.23 - Certain aircraft arriving from areas south of the U.S.

Code of Federal Regulations, 2013 CFR

2013-04-01

... U.S. 122.23 Section 122.23 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... inner boundary of the Atlantic (Coastal) Air Defense Identification Zone (ADIZ) south of 30 degrees north latitude, anywhere outside of the inner boundary of the Gulf of Mexico (Coastal) ADIZ, or anywhere...

19 CFR 122.23 - Certain aircraft arriving from areas south of the U.S.

Code of Federal Regulations, 2010 CFR

2010-04-01

... U.S. 122.23 Section 122.23 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... inner boundary of the Atlantic (Coastal) Air Defense Identification Zone (ADIZ) south of 30 degrees north latitude, anywhere outside of the inner boundary of the Gulf of Mexico (Coastal) ADIZ, or anywhere...

A Transfer Subject: Tracing Boundary-Work and Micro-Transfer in First-Year Composition

ERIC Educational Resources Information Center

Medina, Dylan London

2017-01-01

This dissertation draws on data from a quarter-long case study implementing a number of social science and humanities research methods. This study was conducted at the University of Washington in two sections of First-Year Composition and investigates the boundary-marking interactions that occur in a writing class by tracing the experiences of…

Final Finding of No Significant Impact for Military Housing Privatization Initiative at Malmstrom Air Force Base, Montana

DTIC Science & Technology

2011-12-15

boundaries. Adjacent to the northern boundary of Jupiter Village lays Site 24CA264, which is an old section of the Chicago , Milwaukee, St. Paul...Ecological Services Montana Field Office 585 Shepard Way Heletla, Montana 59601 -6287 Phone: (406) 449-5225 Fax: (406) 449-5339 July 2, 2009

7 CFR 25.103 - Area size and boundary requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... requirements. A nominated area: (1) May not exceed one thousand square miles in total land area; (2) Must have... section to Round II, Round IIS and Round III designations: (i) A Census tract larger than 1,000 square miles shall be reduced to a 1,000 square mile area with a continuous boundary, if necessary, after...

7 CFR 25.103 - Area size and boundary requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... requirements. A nominated area: (1) May not exceed one thousand square miles in total land area; (2) Must have... section to Round II, Round IIS and Round III designations: (i) A Census tract larger than 1,000 square miles shall be reduced to a 1,000 square mile area with a continuous boundary, if necessary, after...

7 CFR 25.103 - Area size and boundary requirements

Code of Federal Regulations, 2010 CFR

2010-01-01

... requirements. A nominated area: (1) May not exceed one thousand square miles in total land area; (2) Must have... section to Round II, Round IIS and Round III designations: (i) A Census tract larger than 1,000 square miles shall be reduced to a 1,000 square mile area with a continuous boundary, if necessary, after...

7 CFR 25.103 - Area size and boundary requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... requirements. A nominated area: (1) May not exceed one thousand square miles in total land area; (2) Must have... section to Round II, Round IIS and Round III designations: (i) A Census tract larger than 1,000 square miles shall be reduced to a 1,000 square mile area with a continuous boundary, if necessary, after...

77 FR 18997 - Boundary Establishment for the Presque Isle National Wild and Scenic River, Ottawa National...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-29

... AGENCY: Forest Service, USDA. ACTION: Notice of availability. SUMMARY: In accordance with Section 3(b) of the Wild and Scenic Rivers Act, the USDA Forest Service, Washington Office, is transmitting the final... Wild and Scenic River boundary is available for review at the following offices: USDA Forest Service...

Species Boundaries and Interrelationships of Solanum Sect. Petota (Wild and Cultivated Potatoes) are Drastically Altered as a Result of PBI-Funded Research

USDA-ARS?s Scientific Manuscript database

In 1990, the latest comprehensive taxonomic monograph of Solanum section Petota Dumort, recognized 232 species partitioned into 21 series. PBI-sponsored research has drastically altered knowledge of their species boundaries and interrelationships. The series contains diploids (2n = 2x = 24), tetrapl...

Species Boundaries and Interrelationships of Solanum Sect. Petota (Wild and Cultivated Potatoes) are Drastically Altered as a Result of PBI-Funded Research

USDA-ARS?s Scientific Manuscript database

In 1990, the latest comprehensive taxonomic monograph of Solanum section Petota Dumort recognized 232 species partitioned into 21 series. PBI-sponsored research has drastically altered knowledge of their species boundaries and interrelationships. The series contains diploids (2n = 2x = 24), tetraplo...

Stable isotope evidence for gradual environmental changes and species survivorship across the Cretaceous/Tertiary Boundary

NASA Astrophysics Data System (ADS)

Barrera, Enriqueta; Keller, Gerta

1990-12-01

High-resolution δ13C and δ18O records have been generated from analyses of the planktonic foraminiferal species Heterohelix globulosa and the benthonic foraminiferal taxon Lenticulina spp from 3 m of a cored section spanning the Cretaceous/Tertiary (K/T) boundary at Brazos River, Texas. These are the first stable isotope records across the K/T boundary based on monospecific and monogeneric foraminiferal samples. They show a gradual decrease in δ13C values of about 2.5 permil beginning at the K/T boundary, as defined by the first appearance of Tertiary planktonic foraminifera, and continuing 17-20 cm above the boundary, approximately 40,000 years later. Gradual 13C depletion contrasts with the sudden δ13C drop at the K/T boundary observed in many deep-sea sections. The surface-to-bottom δ13C gradient decreased to less than zero approximately 25,000-30,000 years after the K/T boundary and remained negative for at least the next 140,000 years. Concomitant with change in δ13C values is a gradual decrease of about 2.5 permil in δ18C values which has not been observed at other localities. This 18O depletion suggests changes in temperature and/or salinity in the earliest Paleocene Gulf of Mexico. No extinction of foraminiferal species is associated with the K/T boundary or the onset of 18O and 13C depletions. Instead, two phases of Cretaceous species extinctions occur. One extinction phase is below the K/T boundary and below the tsunami bed of Bourgeois et al. [1988] and may be linked to sea level regression and environmental perturbations. The second extinction phase coincides with the minimum in δ13C and δ18O values in the Early Danian (Zone P0/Pla) and appears directly related to environmental changes reflected in the isotopic record. H. globulosa, which is commonly present in Maastrichtian and Danian sediments, exhibits significantly lower 18O/16O and 13C/12C ratios in Tertiary sediments relative to specimens from Maastrichtian sediments, demonstrating the survival of this important Cretaceous taxon after the K/T boundary event.

General stability of composite panels reinforced with flexible rods taking account of the side boundary conditions

NASA Astrophysics Data System (ADS)

Dudchenko, A. A.; Elpat'evskii, A. N.

1995-07-01

Reinforced panels are the basic load-bearing elements of various structures. Optimization of massive structures requires consideration of deformation of the panel cross-sections. This is particularly important in determining the bearing strength at buckling. The load scheme, conditions for fixation of the panel cross-section, and bend-torsional stiffness taking account of the deformation of the rod cross-section affect the buckling load in real structures. The stress distribution prior to buckling must be known to solve the buckling problem properly. The stress in the panel is proportional to the active load. The stress distribution is assumed to be known according to our previous method [1]. The load scheme and panel dimensions are shown in Fig. 1. The stress distribution in the panel prior to buckling can be found using Eqs. (1)-(3). A view of the cross-section is given in Fig. 1. The displacements in the panel at buckling for the boundary area are found using Eqs. (4)-(6), while the stresses in the skin and stiffness are found using Eq. (7). Roots k1 and k2 are those of the characteristic equation and β is a dimensionless coordinate. The problem was solved using variational theory. The potential energy is given by Eqs. (8) and (9) by orihogonalization of Eqs. (5). The basic equations are converted to Eqs. (10) by evaluation of the components in Eqs. (8) and (9). Its calculation (11) gives the compression load. Optimization of parameter α gives the critical strength P1 = 6.93 kN (without taking account of the boundary area) and P2 = 5.31 kN (taking account of the boundary area).

Impact ejecta at the Paleocene-Eocene boundary.

PubMed

Schaller, Morgan F; Fung, Megan K; Wright, James D; Katz, Miriam E; Kent, Dennis V

2016-10-14

Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E boundary. Copyright © 2016, American Association for the Advancement of Science.

A one-dimensional sectional model to simulate multicomponent aerosol dynamics in the marine boundary layer 3. Numerical methods and comparisons with exact solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelbard, F.; Fitzgerald, J.W.; Hoppel, W.A.

1998-07-01

We present the theoretical framework and computational methods that were used by {ital Fitzgerald} {ital et al.} [this issue (a), (b)] describing a one-dimensional sectional model to simulate multicomponent aerosol dynamics in the marine boundary layer. The concepts and limitations of modeling spatially varying multicomponent aerosols are elucidated. New numerical sectional techniques are presented for simulating multicomponent aerosol growth, settling, and eddy transport, coupled to time-dependent and spatially varying condensing vapor concentrations. Comparisons are presented with new exact solutions for settling and particle growth by simultaneous dynamic condensation of one vapor and by instantaneous equilibration with a spatially varying secondmore » vapor. {copyright} 1998 American Geophysical Union« less

27 CFR 9.38 - Cienega Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... southeast portion of Section 21, Township 14 South, Range 6 East. (1) From the beginning point, the boundary... Township 14 South, Range 6 East, Section 21; (2) Thence in a straight line to the southwest portion of Section 28, Township 14 South, Range 6 East, where the 1400-foot contour line intersects the south border...

27 CFR 9.38 - Cienega Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

... southeast portion of Section 21, Township 14 South, Range 6 East. (1) From the beginning point, the boundary... Township 14 South, Range 6 East, Section 21; (2) Thence in a straight line to the southwest portion of Section 28, Township 14 South, Range 6 East, where the 1400-foot contour line intersects the south border...

Automated boundary detection of the optic disc and layer segmentation of the peripapillary retina in volumetric structural and angiographic optical coherence tomography.

PubMed

Zang, Pengxiao; Gao, Simon S; Hwang, Thomas S; Flaxel, Christina J; Wilson, David J; Morrison, John C; Huang, David; Li, Dengwang; Jia, Yali

2017-03-01

To improve optic disc boundary detection and peripapillary retinal layer segmentation, we propose an automated approach for structural and angiographic optical coherence tomography. The algorithm was performed on radial cross-sectional B-scans. The disc boundary was detected by searching for the position of Bruch's membrane opening, and retinal layer boundaries were detected using a dynamic programming-based graph search algorithm on each B-scan without the disc region. A comparison of the disc boundary using our method with that determined by manual delineation showed good accuracy, with an average Dice similarity coefficient ≥0.90 in healthy eyes and eyes with diabetic retinopathy and glaucoma. The layer segmentation accuracy in the same cases was on average less than one pixel (3.13 μm).

Automated boundary detection of the optic disc and layer segmentation of the peripapillary retina in volumetric structural and angiographic optical coherence tomography

PubMed Central

Zang, Pengxiao; Gao, Simon S.; Hwang, Thomas S.; Flaxel, Christina J.; Wilson, David J.; Morrison, John C.; Huang, David; Li, Dengwang; Jia, Yali

2017-01-01

To improve optic disc boundary detection and peripapillary retinal layer segmentation, we propose an automated approach for structural and angiographic optical coherence tomography. The algorithm was performed on radial cross-sectional B-scans. The disc boundary was detected by searching for the position of Bruch’s membrane opening, and retinal layer boundaries were detected using a dynamic programming-based graph search algorithm on each B-scan without the disc region. A comparison of the disc boundary using our method with that determined by manual delineation showed good accuracy, with an average Dice similarity coefficient ≥0.90 in healthy eyes and eyes with diabetic retinopathy and glaucoma. The layer segmentation accuracy in the same cases was on average less than one pixel (3.13 μm). PMID:28663830

A Gaussian Mixture Model-based continuous Boundary Detection for 3D sensor networks.

PubMed

Chen, Jiehui; Salim, Mariam B; Matsumoto, Mitsuji

2010-01-01

This paper proposes a high precision Gaussian Mixture Model-based novel Boundary Detection 3D (BD3D) scheme with reasonable implementation cost for 3D cases by selecting a minimum number of Boundary sensor Nodes (BNs) in continuous moving objects. It shows apparent advantages in that two classes of boundary and non-boundary sensor nodes can be efficiently classified using the model selection techniques for finite mixture models; furthermore, the set of sensor readings within each sensor node's spatial neighbors is formulated using a Gaussian Mixture Model; different from DECOMO [1] and COBOM [2], we also formatted a BN Array with an additional own sensor reading to benefit selecting Event BNs (EBNs) and non-EBNs from the observations of BNs. In particular, we propose a Thick Section Model (TSM) to solve the problem of transition between 2D and 3D. It is verified by simulations that the BD3D 2D model outperforms DECOMO and COBOM in terms of average residual energy and the number of BNs selected, while the BD3D 3D model demonstrates sound performance even for sensor networks with low densities especially when the value of the sensor transmission range (r) is larger than the value of Section Thickness (d) in TSM. We have also rigorously proved its correctness for continuous geometric domains and full robustness for sensor networks over 3D terrains.

Taxonomic changes in Solanum section Petota

USDA-ARS?s Scientific Manuscript database

In 1990, the latest comprehensive taxonomic monograph of Solanum section Petota Dumort. recognized 236 species partitioned into 21 series. Of these, 227 were tuber-bearing and nine non-tuber-bearing. NSF-sponsored research has drastically altered knowledge of their species boundaries and interrelati...

On 3-D inelastic analysis methods for hot section components (base program)

NASA Technical Reports Server (NTRS)

Wilson, R. B.; Bak, M. J.; Nakazawa, S.; Banerjee, P. K.

1986-01-01

A 3-D Inelastic Analysis Method program is described. This program consists of a series of new computer codes embodying a progression of mathematical models (mechanics of materials, special finite element, boundary element) for streamlined analysis of: (1) combustor liners, (2) turbine blades, and (3) turbine vanes. These models address the effects of high temperatures and thermal/mechanical loadings on the local (stress/strain)and global (dynamics, buckling) structural behavior of the three selected components. Three computer codes, referred to as MOMM (Mechanics of Materials Model), MHOST (Marc-Hot Section Technology), and BEST (Boundary Element Stress Technology), have been developed and are briefly described in this report.

Harmonic oscillations of a longitudinal shear infinite hollow cylinder arbitrary cross-section with a tunnel crack

NASA Astrophysics Data System (ADS)

Kyrylova, O. I.; Popov, V. G.

2018-04-01

An effective analytical-numerical method for determining the dynamic stresses in a hollow cylindrical body of arbitrary cross-section with a tunnel crack under antiplane strain conditions is proposed. The method allows separately solving the integral equations on the crack faces and satisfying the boundary conditions on the body boundaries. It provides a convenient numerical scheme. Approximate formulas for calculating the dynamic stress intensity factors in a neighborhood of the crack are obtained and the influence of the crack geometry and wave number on these quantities is investigated, especially from the point of view of the resonance existence.

Solutions of the Helmholtz equation with boundary conditions for force-free magnetic fields

NASA Technical Reports Server (NTRS)

Rasband, S. N.; Turner, L.

1981-01-01

It is shown that the solution, with one ignorable coordinate, for the Taylor minimum energy state (resulting in a force-free magnetic field) in either a straight cylindrical or a toroidal geometry with arbitrary cross section can be reduced to the solution of either an inhomogeneous Helmholtz equation or a Grad-Shafranov equation with simple boundary conditions. Standard Green's function theory is, therefore, applicable. Detailed solutions are presented for the Taylor state in toroidal and cylindrical domains having a rectangular cross section. The focus is on solutions corresponding to the continuous eigenvalue spectra. Singular behavior at 90 deg corners is explored in detail.

New Cricetid Rodents from Strata near the Eocene-Oligocene Boundary in Erden Obo Section (Nei Mongol, China).

PubMed

Li, Qian; Meng, Jin; Wang, Yuanqing

2016-01-01

New cricetids (Eucricetodon wangae sp. nov., Eucricetodon sp. and Pappocricetodon siziwangqiensis sp. nov.) are reported from the lower and middle parts of the "Upper Red" beds of the Erden Obo section in Nei Mongol, China. Eucricetodon wangae is more primitive than other known species of the genus from lower Oligocene of Asia and Europe in having a single anterocone on M1, a single connection between the protocone and the paracone, the anterior metalophule connection in M1-2 and weaker anteroconid and ectomesolophid in lower molars. Pappocricetodon siziwangqiensis is more advanced than other species of the genus in permanently missing P4 and having posterior protolophule connection. These fossils suggest that the age of the "Upper Red" of the Erden Obo section is younger than the age of the Upper Eocene Houldjin and Caijiachong formations, but older than those containing the Shandgolian faunas; the "Upper Red" is most closely correlative to the Ergilian beds in age, and probably close to the Eocene/Oligocene boundary. Given the age estimate, Eucricetodon wangae provides the new evidence to support that cricetid dispersal from Asia to Europe occurred prior to the Eocene-Oligocene boundary.

15 CFR 921.33 - Boundary changes, amendments to the management plan, and addition of multiple-site components.

Code of Federal Regulations, 2010 CFR

2010-01-01

... management plan, and addition of multiple-site components. 921.33 Section 921.33 Commerce and Foreign Trade... management plan, and addition of multiple-site components. (a) Changes in the boundary of a Reserve and major... management plan shall address goals and objectives for all components of the multi-site Reserve and the...

27 CFR 9.215 - Lake Chelan.

Code of Federal Regulations, 2014 CFR

2014-04-01

... section 10 for 0.3 mile to its intersection with the 2,520-foot contour line and a 90-degree turn in the... boundary line 0.3 mile to its intersection with the 2,600-foot contour line and a 90-degree turn in the WNF... Landing. From the beginning point, proceed straight east 1.6 miles along the northern boundary line of...

Theoretical Calculation of Viscous-Inviscid Transonic Flows.

DTIC Science & Technology

1980-08-01

Taylor Naval Ship Research and Development Center Aviation and Surface Effects Department / (See reverse side) Bethesda, Maryland 20084 ! CONTROLLING...Interactions ... .......... ... 46 18 -ffect of Boundary Layer on Blade Surface Pressures in a Transonic Fan Rotor Tip Section Cascade...complicated by the viscous effect . The strong viscous-inviscid interaction caused by the shock wave thickens the boundary layer rapidly, and the flow eventually

Application of boundary integral equations to elastoplastic problems

NASA Technical Reports Server (NTRS)

Mendelson, A.; Albers, L. U.

1975-01-01

The application of boundary integral equations to elastoplastic problems is reviewed. Details of the analysis as applied to torsion problems and to plane problems is discussed. Results are presented for the elastoplastic torsion of a square cross section bar and for the plane problem of notched beams. A comparison of different formulations as well as comparisons with experimental results are presented.

Active electromagnetic invisibility cloaking and radiation force cancellation

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2018-03-01

This investigation shows that an active emitting electromagnetic (EM) Dirichlet source (i.e., with axial polarization of the electric field) in a homogeneous non-dissipative/non-absorptive medium placed near a perfectly conducting boundary can render total invisibility (i.e. zero extinction cross-section or efficiency) in addition to a radiation force cancellation on its surface. Based upon the Poynting theorem, the mathematical expression for the extinction, radiation and amplification cross-sections (or efficiencies) are derived using the partial-wave series expansion method in cylindrical coordinates. Moreover, the analysis is extended to compute the self-induced EM radiation force on the active source, resulting from the waves reflected by the boundary. The numerical results predict the generation of a zero extinction efficiency, achieving total invisibility, in addition to a radiation force cancellation which depend on the source size, the distance from the boundary and the associated EM mode order of the active source. Furthermore, an attractive EM pushing force on the active source directed toward the boundary or a repulsive pulling one pointing away from it can arise accordingly. The numerical predictions and computational results find potential applications in the design and development of EM cloaking devices, invisibility and stealth technologies.

Vehicle cabin cooling system for capturing and exhausting heated boundary layer air from inner surfaces of solar heated windows

DOEpatents

Farrington, Robert B.; Anderson, Ren

2001-01-01

The cabin cooling system includes a cooling duct positioned proximate and above upper edges of one or more windows of a vehicle to exhaust hot air as the air is heated by inner surfaces of the windows and forms thin boundary layers of heated air adjacent the heated windows. The cabin cooling system includes at least one fan to draw the hot air into the cooling duct at a flow rate that captures the hot air in the boundary layer without capturing a significant portion of the cooler cabin interior air and to discharge the hot air at a point outside the vehicle cabin, such as the vehicle trunk. In a preferred embodiment, the cooling duct has a cross-sectional area that gradually increases from a distal point to a proximal point to the fan inlet to develop a substantially uniform pressure drop along the length of the cooling duct. Correspondingly, this cross-sectional configuration develops a uniform suction pressure and uniform flow rate at the upper edge of the window to capture the hot air in the boundary layer adjacent each window.

Morphology of Proeutectoid Ferrite

NASA Astrophysics Data System (ADS)

Yin, Jiaqing; Hillert, Mats; Borgenstam, Annika

2017-03-01

The morphology of grain boundary nucleated ferrite particles in iron alloys with 0.3 mass pct carbon has been classified according to the presence of facets. Several kinds of particles extend into both grains of austenite and have facets to both. It is proposed that they all belong to a continuous series of shapes. Ferrite plates can nucleate directly on the grain boundary but can also develop from edges on many kinds of particles. Feathery structures of parallel plates on both sides of a grain boundary can thus form. In sections, parallel to their main growth direction, plates have been seen to extend the whole way from the nucleation site at the grain boundary and to the growth front. This happens in the whole temperature range studied from 973 K to 673 K (700 °C to 400 °C). The plates thus grow continuously and not by subunits stopping at limited length and continuing the growth by new ones nucleating. Sometimes, the plates have ridges and in oblique sections they could be mistaken for the start of new plates. No morphological signs were observed indicating a transition between Widmanstätten ferrite and bainitic ferrite. It is proposed that there is only one kind of acicular ferrite.

Deciphering the magnetic and mineralogical record of the Deccan Traps at the Cretaceous-Paleogene boundary of the Zumaia section, Basque-Cantabric basin (Spain)

NASA Astrophysics Data System (ADS)

Font, Eric; Adatte, Thierry; Andrade, Mariana; Keller, Gerta; Mbabi Bitchong, André; Carvallo, Claire; Ferreira, Joana; Diogo, Zenaida; Mirão, José

2017-04-01

The Deccan Traps Magmatic Province coincides with the Cretaceous-Paleogene (KPg) boundary and probably contributed to the associated mass extinctions by inducing rapid and abrupt climate changes, including continental and superficial seawater acidification. However, how such environmental acidification is expressed in the marine sedimentary record is still poorly constrained. Recent environmental magnetic studies of the Bidart (France) and Gubbio (Italy) sections proposed new benchmarks to identify the Deccan Traps fingerprint in the marine sedimentary record, namely anomalous concentration in mercury, presence of akagenéite (a Cl-rich oxy-hydroxide forming in hyper-chlorinated and acid conditions) and the loss of detrital and biogenic magnetite by acid reductive dissolution. Here we test this scenario on the Zumaia section, Spain, a reference KPg section cropping out in the Basque-Cantabric basin. Our results confirm the presence of an iron-depleted interval located just below the KPg boundary, similarly to Bidart and Gubbio, and which contains significant amounts of akaganéite grains as well as high content in mercury. These results consolidate the use of the previously cited benchmarks to identify environmental and climate changes induced by the Deccan volcanism. It also suggests that the main eruptive Deccan phase began just before the KPg extinction, reinforcing its contribution in the KPg mass extinction. Publication supported by FCT- project UID/GEO/50019/2013 - Instituto Dom Luiz

33 CFR 162.210 - Lake Tahoe, Calif.; restricted areas along south shore.

Code of Federal Regulations, 2011 CFR

2011-07-01

... line of Lot 2, Section 26, Township 13 North (Mount Diablo Base Line), Range 17 East (Mount Diablo..., Section 6, Township 12 North (Mount Diablo Base Line), Range 18 East (Mount Diablo Meridian); thence north... boundary line of Lot 1, Section 32, Township 13 North (Mount Diablo Base Line), Range 18 East (Mount Diablo...

33 CFR 162.210 - Lake Tahoe, Calif.; restricted areas along south shore.

Code of Federal Regulations, 2010 CFR

2010-07-01

... line of Lot 2, Section 26, Township 13 North (Mount Diablo Base Line), Range 17 East (Mount Diablo..., Section 6, Township 12 North (Mount Diablo Base Line), Range 18 East (Mount Diablo Meridian); thence north... boundary line of Lot 1, Section 32, Township 13 North (Mount Diablo Base Line), Range 18 East (Mount Diablo...

LayTracks3D: A new approach for meshing general solids using medial axis transform

DOE PAGES

Quadros, William Roshan

2015-08-22

This study presents an extension of the all-quad meshing algorithm called LayTracks to generate high quality hex-dominant meshes of general solids. LayTracks3D uses the mapping between the Medial Axis (MA) and the boundary of the 3D domain to decompose complex 3D domains into simpler domains called Tracks. Tracks in 3D have no branches and are symmetric, non-intersecting, orthogonal to the boundary, and the shortest path from the MA to the boundary. These properties of tracks result in desired meshes with near cube shape elements at the boundary, structured mesh along the boundary normal with any irregular nodes restricted to themore » MA, and sharp boundary feature preservation. The algorithm has been tested on a few industrial CAD models and hex-dominant meshes are shown in the Results section. Work is underway to extend LayTracks3D to generate all-hex meshes.« less

22 CFR 1104.1 - Purpose.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Purpose. 1104.1 Section 1104.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.1 Purpose. (a) The regulations in this part implement...

Development of an integrated BEM approach for hot fluid structure interaction

NASA Technical Reports Server (NTRS)

Dargush, Gary F.; Banerjee, Prasanta K.; Honkala, Keith A.

1988-01-01

In the present work, the boundary element method (BEM) is chosen as the basic analysis tool, principally because the definition of temperature, flux, displacement and traction are very precise on a boundary-based discretization scheme. One fundamental difficulty is, of course, that a BEM formulation requires a considerable amount of analytical work, which is not needed in the other numerical methods. Progress made toward the development of a boundary element formulation for the study of hot fluid-structure interaction in Earth-to-Orbit engine hot section components is reported. The primary thrust of the program to date has been directed quite naturally toward the examination of fluid flow, since boundary element methods for fluids are at a much less developed state.

Zero-G experiments in two-phase fluids flow regimes

NASA Technical Reports Server (NTRS)

Heppner, D. B.; King, C. D.; Littles, J. W.

1975-01-01

The two-phase flows studied were liquid and gas mixtures in a straight flow channel of circular cross-section. Boundaries between flow regimes have been defined for normogravity on coordinates of gas quality and total mass velocity; and, when combined with boundary expressions having a Froude number term, an analytical model was derived predicting boundary shifts with changes in gravity level. Experiments with air and water were performed, first in the normogravity environment of a ground laboratory and then in 'zero gravity' aboard a KC-135 aircraft flying parabolic trajectories. Data reduction confirmed regime boundary shifts in the direction predicted, although the magnitude was a little less than predicted. Pressure drop measurements showed significant increases for the low gravity condition.

Abrupt Changes at the Permian/Triassic Boundary: Tempo of Events from High-Resolution Cyclostratigraphy

NASA Technical Reports Server (NTRS)

Rampino, M. R.; Prokoph, A.; Adler, A. C.

2000-01-01

The Permian/Triassic (P/Tr) boundary (251.4 +/- 3 Myr) is marked by the most severe mass extinction in the geologic record. Recently, precise absolute dating has bracketed the marine extinctions and associated carbon-isotope anomaly within less than 1 Myr. We improve this resolution through high-resolution stratigraphy across the P/Tr boundary in the 331-m Gartnerkofel-1 core and nearby Reppwand outcrop section (Carnic Alps, Austria) utilizing FFT and wavelet timeseries analyses of cyclic components in down-hole core logs of density and natural gamma-ray intensity, and carbon-isotopic ratios of bulk samples. The wavelet analysis indicates continuity of deposition across the P/Tr boundary interval, and the timeseries analyses show evidence for persistent cycles in the ratio of approximately 40: 10: 4.7: 2.3 meters, correlated with Milankovitch-band orbital cycles of approximately 412: 100: 40: 20 kyr (eccentricity 1 and 2, obliquity, and precession), and giving a consistent average sedimentation rate of approximately 10 cm/1,000 yr. Milankovitch periods in delta C-13 and density in these shallow-water carbonates were most likely the result of climatically induced oscillations of sea level and climate, coupled with changes in ocean circulation and productivity, that affected sedimentation. Fluctuations in gamma radiation reflect varying input of clay minerals and the presence of shaly interbeds. Throughout the P/Tr boundary interval in the core, the 100,000-year eccentricity cycle seems to be dominant. Weaker obliquity and precession cycles are in line with the location of the Austrian section in the latest Permian, close to the Equator in the western bight of the Tethys, where obliquity and precessional effects on seasonal contrast might be subdued. Using the improved resolution provided by cycle analysis in the GK-1 core, we find that the dramatic change in the faunal record that marks the P/Tr boundary takes place over less than 6m, or less than 60,000 years. In the nearby Reppwand outcrop section, the same faunal changes occurs over only 0.8 m or about 8,000 years, close to the limit of time-resolution induced by bioturbation and reworking in these sediments. The sharp negative global carbon-isotope shift took place within less than or equal to 40,000 yr, and the isotope excursions persisted for approximately 480,000 yr into the Early Triassic. The results indicate that the severe marine faunal event that marks the P/Tr boundary was very sudden, perhaps less than the resolution window in the GK-1 core, and suggest a catastrophic cause. The wavelet-analysis approach to high-resolution cyclostratigraphy can be applied to other P/Tr boundary sections, and when combined with precise absolute dating and magnetostratigraphic methods promises a significant increase in resolution in determining the correlation and tempo of the end-Permian extinctions and related events worldwide.

The Disposition of Pt, Pd, Ir, Os, and Ru in Marine Sediments and the K/T Boundary

NASA Technical Reports Server (NTRS)

Lee, Cin-Ty; Wasserburg, Gerald; Kyte, Frank

2003-01-01

The marine record of platinum group elements (PGEs) and Os isotopic compositions provides information on different inputs of PGEs into the oceans. Some studies based on a smaller subset of the PGEs suggest that the PGEs may suffer post-depositional mobility during diagenesis. In some K/T boundary clays, Kyte and others showed that the relative abundances of Pt, Pd, Ir, and Os can differ significantly from chondritic, which is the signature expected from fallout of the meteorite impact. In some K/T boundary sections, elevated Ir concentrations are observed as far as 1 meter from the cm-thick boundary clay containing the meteoritic ejecta. The purpose of this study was to characterize Pt, Pd, Ir, Os, and Ru abundances in zones including the K/T boundary. We determined PGE abundances of boundary clays at two hemipelagic sites (Stevns Klint, Denmark and Caravaca, Spain) in which previous studies by Kyte and others showed that the Ir anomaly is confined to within a few cm. We also analyzed two pelagic Pacific sites: a boundary clay from the north Pacific (Hole 465A) characterized by a 0.5 m thick Ir anomaly and a transect across the K/T boundary from the south Pacific (Hole 596) where the Ir anomaly spans 2 m. The Stevns Klint, Caravaca, and north Pacific sites are characterized by abundant marls and limestones in the section, whereas the south Pacific site is dominated by clays. Samples were spiked with isotopic tracers, mixed with a flux, S and Ni, and equilibrated by fusion. PGEs were extracted from the Ni and analyzed on a Finnigan Element ICP-MS. We find that the narrow Caravaca and Stevns Klint boundary clays have relative PGE abundance patterns indistinguishable from chondritic values. The two Pacific sites were found to have nearly identical PGE patterns but have ratios at the peak, which differ from chondritic values as found earlier by Evans et al. The Pacific sites were found to have nearly identical PGE patterns but are extremely depleted in OS (Os/Ir = 0.07-0.15) and slightly enriched in Pd and Pt relative to Ir.

Towards a definition of the Induan-Olenekian Boundary: The potential of Eurygnathodus costatus and Eurygnathodus hamadai as index fossils

NASA Astrophysics Data System (ADS)

Horacek, Micha; Krystyn, Leopold

2017-04-01

Extended research in Spiti, Himalaya and published data from sections in other Tethys regions demonstrate a convincing timely correspondence between the FO of Nv.w. waageni and that of Eurygnathodus costatus and E. hamadai. Presence of the latter two species appearing successively has been documented in detail in several Tethyan sections, e.g. China (Chaohu), India (Mud) and Slovenia (Ciri). Occurrences of E. costatus and/or E. hamadei additionally are known from various other sections in Fareast Russia (South Primoye), Japan, China (e.g. Daxiakou, Guandao), Malaysia, Vietnam, Oman, Croatia and Italy (Southern Alps). They have been reported as occurring over only a short period around the Induan-Olenekian Boundary (IOB) and are present even in very shallow marine sections that are generally poor in time diagnostic offshore conodonts. E. costatus usually occurs at the onset of the steep increase in carbon isotopes in the shallow water sections and E. hamadai follows immediately after the maximum of the IOB positive carbon isotope peak. The common occurrence of the two Eurygnathodus species around the IOB - and their restriction to the boundary interval - makes them potential candidates as index fossils or at least as primary proxies for the IOB, yet in need to be internationally defined. Furthermore, and adverse to the Nv. waageni group, both species are very easily recognizable. Disadvantageous are the absence of the Eurygnathodus species in the Boreal region and it thus cannot be used there. A still open question is the presence of Eurygnathodus in the Panthalassa realm: despite both its species have been reported from sections in Japan they still have to be detected in North America.

Marine ostracod turnover tracks orbitally forced palaeoenvironmental changes at the Lower-Middle Pleistocene transition: the case study of the Valle di Manche section (Calabria, southern Italy)

NASA Astrophysics Data System (ADS)

Rossi, Veronica; Scarponi, Daniele; Capraro, Luca; Ferretti, Patrizia; Macrì, Patrizia

2017-04-01

Ostracods, small crustaceans living in almost every aquatic depositional setting, are widely used in palaeoenvironmental reconstructions due to their well-known ecological sensitivity. A close connection between the composition of ostracod fauna and the Milankovitch climate-eustatic variability has been documented in several Plio-Pleistocene marine sections of the Central Mediterranean area. The Valle di Manche section (VdM; Calabria, southern Italy), one of the suitable candidates to host the Global Stratotype Section and Point (GSSP) of the Ionian Stage-Middle Pleistocene, represents an ideal venue where to investigate ostracod turnover in relation to orbitally forced palaeoenvironmental changes, being firmly constrained in time and well documented by a number of independent climatic proxy. A high-resolution, quantitative analysis of the ostracod fauna has been undertaken on the middle part of the VdM, ca. 30 m-thick and showing two T-R cycles developed at the Lower-Middle Pleistocene transition (late MIS 21 to early MIS 18). Within each cycle, a relatively thin, fining-upward transgressive muddy unit is overlain by gradually coarsening upward and more expanded regressive silty to sand packages. A total of 40 samples have been selected to characterise the whole spectrum of lithofacies and detect high-frequency palaeoenvironmental variations especially within homogeneous clayey stratigraphic intervals. Taxa typical of circalittoral (>70/100 m) depths (e.g., Bosquetina dentata, Cytherella vulgatella, Cytheropteron monoceros, Pterygocythereis ceratoptera and Krithe species), commonly accompanied by the lower circalittoral-bathyal species Henryhowella sarsii, occur within the fine-grained units developed during the full interglacials of MIS 21 and MIS 19. Furthermore, ostracod assemblages document that the oxygen availability at the sea floor changed during MIS 19. In contrast, a less-diversified ostracod fauna dominated by Aurila convexa, a species preferring vegetated sandy substrates in the upper circalittoral zone, characterises coarser glacial deposits. Atop the sandy successions A. convexa is partially replaced by Semicytherura ruggierii, suggesting a further decrease in palaeobathymetry and, possibly, an increase in riverine influence. Within each T-R cycle vertical changes in ostracod fauna track both an overall deepening-shallowing upward trend and high-frequency variations in stratal stacking patterns, allowing the precise identification of key sequence stratigraphic surfaces: Transgressive Surface (TS) and Maximum Flooding Surface (MFS). The former, which is marked by a sharp increase in Krithe, Cytherella and Cytheropteron species, develops during the late d18O glacial termination. The MFS, invariably highlighted by concomitant highest and lowest percentages of H. sarsii and A. convexa respectively, matches the lightest d18O values recorded by foraminifers and corresponding to full interglacial conditions. Within the MIS 19 muddy unit, the MFS is identified few decimeters above the Pitagora ash layer, a prominent bed close to the Matuyama-Brunhes geomagnetic reversal.

Wind tunnel-sidewall-boundary-layer effects in transonic airfoil testing-some correctable, but some not

NASA Technical Reports Server (NTRS)

Lynch, F. T.; Johnson, C. B.

1988-01-01

The need to correct transonic airfoil wind tunnel test data for the influence of the tunnel sidewall boundary layers, in addition to the wall accepted corrections for the analytical investigation was carried out in order to evaluate sidewall boundary layer effects on transonic airfoil characteristics, and to validate proposed correction and the limit to their applications. This investigation involved testing of modern airfoil configurations in two different transonic airfoil test facilities, the 15 x 60 inch two-dimensional insert of the National Aeronautical Establishment (NAE) 5 foot tunnel in Ottawa, Canada, and the two-dimensional test section of the NASA Langley 0.3 m Transonic Cryogenic Tunnel (TCT). Results presented included effects of variations in sidewall-boundary layer bleed in both facilities, different sidewall boundary layer correction procedures, tunnel-to tunnel comparisons of correcte results, and flow conditions with and without separation.

Nonlinear power flow feedback control for improved stability and performance of airfoil sections

DOEpatents

Wilson, David G.; Robinett, III, Rush D.

2013-09-03

A computer-implemented method of determining the pitch stability of an airfoil system, comprising using a computer to numerically integrate a differential equation of motion that includes terms describing PID controller action. In one model, the differential equation characterizes the time-dependent response of the airfoil's pitch angle, .alpha.. The computer model calculates limit-cycles of the model, which represent the stability boundaries of the airfoil system. Once the stability boundary is known, feedback control can be implemented, by using, for example, a PID controller to control a feedback actuator. The method allows the PID controller gain constants, K.sub.I, K.sub.p, and K.sub.d, to be optimized. This permits operation closer to the stability boundaries, while preventing the physical apparatus from unintentionally crossing the stability boundaries. Operating closer to the stability boundaries permits greater power efficiencies to be extracted from the airfoil system.

International boundary experiences by the United Nations

NASA Astrophysics Data System (ADS)

Kagawa, A.

2013-12-01

Over the last few decades, the United Nations (UN) has been approached by Security Council and Member States on international boundary issues. The United Nations regards the adequate delimitation and demarcation of international boundaries as a very important element for the maintenance of peace and security in fragile post-conflict situations, establishment of friendly relationships and cross-border cooperation between States. This paper will present the main principles and framework the United Nations applies to support the process of international boundary delimitation and demarcation activities. The United Nations is involved in international boundary issues following the principle of impartiality and neutrality and its role as mediator. Since international boundary issues are multi-faceted, a range of expertise is required and the United Nations Secretariat is in a good position to provide diverse expertise within the multiple departments. Expertise in different departments ranging from legal, political, technical, administrative and logistical are mobilised in different ways to provide support to Member States depending on their specific needs. This presentation aims to highlight some of the international boundary projects that the United Nations Cartographic Section has been involved in order to provide the technical support to different boundary requirements as each international boundary issue requires specific focus and attention whether it be in preparation, delimitation, demarcation or management. Increasingly, the United Nations is leveraging geospatial technology to facilitate boundary delimitation and demarcation process between Member States. Through the presentation of the various case studies ranging from Iraq - Kuwait, Israel - Lebanon (Blue Line), Eritrea - Ethiopia, Cyprus (Green Line), Cameroon - Nigeria, Sudan - South Sudan, it will illustrate how geospatial technology is increasingly used to carry out the support. In having applied a range of geospatial solutions, some of the good practices that have been applied in preceding projects, but there have been challenges and limitations faced. However, these challenges need to be seen as an opportunity to improve the geospatial technology solutions in future international boundary projects. This presentation will also share the aspirations that the United Nations Cartographic Section has in becoming a facilitator in geospatial technical aspects related to international boundary issues as we increasingly develop our geospatial institutional knowledge base and expertise. The presentation will conclude by emphasizing the need for more collaboration between different actors dealing with geospatial technology on borderland issues in order to meet the main goal of the United Nations - to live and work together as "We the Peoples of the United Nations".

40 CFR 55.14 - Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Requirements that apply to OCS sources... REGULATIONS § 55.14 Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by State. (a) The requirements of this section shall apply to OCS sources as set forth below. In...

A recurrence matrix method for the analysis of longitudinal and torsional vibrations in non-uniform multibranch beams with variable boundary conditions

NASA Technical Reports Server (NTRS)

Davis, R. B.; Stephens, M. V.

1974-01-01

An approximate method for calculating the longitudinal and torsional natural frequencies and associated modal data of a beamlike, variable cross section multibranch structure is presented. The procedure described is the numerical integration of the first order differential equations that characterize the beam element in longitudinal motion and that satisfy the appropriate boundary conditions.

33 CFR 161.55 - Vessel Traffic Service Puget Sound and the Cooperative Vessel Traffic Service for the Juan de...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Sound and the Cooperative Vessel Traffic Service for the Juan de Fuca Region. 161.55 Section 161.55... the Juan de Fuca Region. The Vessel Traffic Service Puget Sound area consists of the navigable waters... International Boundary through the waters known as the Strait of Juan de Fuca, Haro Strait, Boundary Pass, and...

33 CFR 161.55 - Vessel Traffic Service Puget Sound and the Cooperative Vessel Traffic Service for the Juan de...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Sound and the Cooperative Vessel Traffic Service for the Juan de Fuca Region. 161.55 Section 161.55... the Juan de Fuca Region. The Vessel Traffic Service Puget Sound area consists of the navigable waters... International Boundary through the waters known as the Strait of Juan de Fuca, Haro Strait, Boundary Pass, and...

A Computer Program for the Prediction of Solid Propellant Rocket Motor Performance. Volume 3

DTIC Science & Technology

1975-07-01

following losses: two-dimensional/two-phase (coupled), nozzle erosion, kinetics, boundary layer, combustion efficiency, submergence . The program...loss •Two dimensional or divergence less •Finite Rate Kinetics loss •Boundary Layer Loss •Combustion Efficiency - • Submergence Loss •Erosion...counted twice. The iforcmcr.tioned assumptions are describ- ed In Section US, The submergence efficiency, ijgno* ^* rased on an empirical

Three-dimensional Stress Analysis Using the Boundary Element Method

NASA Technical Reports Server (NTRS)

Wilson, R. B.; Banerjee, P. K.

1984-01-01

The boundary element method is to be extended (as part of the NASA Inelastic Analysis Methods program) to the three-dimensional stress analysis of gas turbine engine hot section components. The analytical basis of the method (as developed in elasticity) is outlined, its numerical implementation is summarized, and the approaches to be followed in extending the method to include inelastic material response indicated.

Dipping Magnetic Reversal Boundaries at Endeavor Deep: Implications for Crustal Accretion

NASA Astrophysics Data System (ADS)

Pockalny, R. A.; Shields, A. C.; Larson, R. L.; Popham, C.

2005-12-01

Endeavor Deep, created by ongoing rifting along the northeastern boundary of the Juan Fernandez Microplate, provides a generous 75-km long view of the upper 1-3 km of oceanic crust created ~3 Ma at a fast-spreading ridge (~80 km/Myr, half-rate). Recent near-bottom surveys with the ROV Jason collected high-resolution video, rock samples, and 3-component magnetometer data along a 5 km-wide section of the southern wall of the deep. The video and rock samples define a crustal section with 300-500 m of primarily pillows and flows overlying a 400-500 m transition zone of extrusives and dykes. Forward modeling of the total magnetic intensity calculated from the 3-component magnetometer data identifies a magnetic polarity reversal that corresponds to a reversal boundary within magnetic anomaly 2a (C2An.2r - C2AN.3n , ~3.33 Ma). The location of the modeled polarity transition suggests the reversal boundary dips downward toward the original ridge axis with shallow dips (15 degrees) in the extrusive layer becoming increasingly steeper (25 degrees) in the deeper transition zone. The dipping character of the reversal boundary has also been observed along the walls of the Blanco Fracture Zone and is consistent with evolving crustal accretion models for seafloor created at intermediate- and fast-spreading rates, which predicts the rotation of the upper extrusive layer back toward the ridge axis. As a consequence of this rotation, originally horizontal flow boundaries will dip back toward the ridge axis and the magnitude of the dip will increase with depth into the crustal section. A small reversed magnetic polarity is also observed deeper within normally magnetized C2AN.3n chron, but with a very shallow dip (3-5 degrees). We doubt this is another normal-reverse-normal polarity transition, since the anomaly suspiciously coincides with the transition from dykes to extrusives. Therefore, we believe this anomaly is either the result of an edge-effect created by the different magnetic properties of the dykes and extrusives or evidence off-axis volcanism that occurred during a more recent period of normal magnetization.

22 CFR 1104.4 - Permit requirements and exceptions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Permit requirements and exceptions. 1104.4 Section 1104.4 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.4 Permit requirements and exceptions...

22 CFR 1104.12 - Custody of archaeological resources.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Custody of archaeological resources. 1104.12 Section 1104.12 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.12 Custody of archaeological...

22 CFR 1104.17 - Confidentiality of archaeological resource information.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Confidentiality of archaeological resource information. 1104.17 Section 1104.17 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.17 Confidentiality...

Cotton fibre cross-section properties

USDA-ARS?s Scientific Manuscript database

From a structural perspective the cotton fibre is a singularly discrete, elongated plant cell with no junctions or inter-cellular boundaries. Its form in nature is essentially unadulterated from the field to the spinning mill where its cross-section properties, as for any textile fibre, are central ...

22 CFR 1104.4 - Permit requirements and exceptions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Permit requirements and exceptions. 1104.4 Section 1104.4 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.4 Permit requirements and exceptions...

22 CFR 1104.17 - Confidentiality of archaeological resource information.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Confidentiality of archaeological resource information. 1104.17 Section 1104.17 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.17 Confidentiality...

22 CFR 1104.12 - Custody of archaeological resources.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Custody of archaeological resources. 1104.12 Section 1104.12 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.12 Custody of archaeological...

The melting and solidification of nanowires

NASA Astrophysics Data System (ADS)

Florio, B. J.; Myers, T. G.

2016-06-01

A mathematical model is developed to describe the melting of nanowires. The first section of the paper deals with a standard theoretical situation, where the wire melts due to a fixed boundary temperature. This analysis allows us to compare with existing results for the phase change of nanospheres. The equivalent solidification problem is also examined. This shows that solidification is a faster process than melting; this is because the energy transfer occurs primarily through the solid rather than the liquid which is a poorer conductor of heat. This effect competes with the energy required to create new solid surface which acts to slow down the process, but overall conduction dominates. In the second section, we consider a more physically realistic boundary condition, where the phase change occurs due to a heat flux from surrounding material. This removes the singularity in initial melt velocity predicted in previous models of nanoparticle melting. It is shown that even with the highest possible flux the melting time is significantly slower than with a fixed boundary temperature condition.

Effects of microstructural variation on Charpy impact properties in heavy-section Mn-Mo-Ni low alloy steel for reactor pressure vessel

NASA Astrophysics Data System (ADS)

Hong, Seokmin; Song, Jaemin; Kim, Min-Chul; Choi, Kwon-Jae; Lee, Bong-Sang

2016-03-01

The effects of microstructural changes in heavy-section Mn-Mo-Ni low alloy steel on Charpy impact properties were investigated using a 210 mm thick reactor pressure vessel. Specimens were sampled from 5 different positions at intervals of 1/4 thickness from the inner surface to the outer surface. A detailed microstructural analysis of impact-fractured specimens showed that coarse carbides along the lath boundaries acted as fracture initiation sites, and cleavage cracks deviated at prior-austenite grain boundaries and bainite lath boundaries. Upper shelf energy was higher and energy transition temperature was lower at the surface positon, where fine bainitic microstructure with homogeneously distributed fine carbides were present. Toward the center, coarse upper bainite and precipitation of coarse inter-lath carbides were observed, which deteriorated impact properties. At the 1/4T position, the Charpy impact properties were worse than those at other positions owing to the combination of elongated-coarse inter-lath carbides and large effective grain size.

Theoretical study of nonadiabatic boundary-layer stabilization times in a cryogenic wind tunnel for typical stainless steel wing and fuselage models

NASA Technical Reports Server (NTRS)

Johnson, C. B.

1980-01-01

The time varying effect of nonadiabatic wall conditions on boundary layer properties was studied for a two dimensional wing section and an axisymmetric fuselage. The wing and fuselage sections are representative of the wing root chord and fuselage of a typical transport model for the National Transonic Facility. The analysis was made with a solid wing and three fuselage configurations (one solid and two hollow with varying skin thicknesses) all made from AISI type 310S stainless steel. The displacement thickness and local skin friction were investigated at a station on the model in terms of the time required for these two boundary layer properties to reach an adiabatic wall condition after a 50 K step change in total temperature. The analysis was made for a free stream Mach number of 0.85, a total temperature of 117 K, and stagnation pressures of 2, 6, and 9 atm.

Vegetation, climatic and floral changes at the Cretaceous-Tertiary boundary

USGS Publications Warehouse

Wolfe, J.A.; Upchurch, G.R.

1986-01-01

he western interior of North America has the only known non-marine sections that contain the iridium-rich clay interpreted as the Cretaceous-Tertiary (K-T) boundary1-7. Because vegetation and climate can be directly inferred from physiognomy of leaves8-15 and because leaf species typically represent low taxonomic categories, studies of leaf floras in these sections provide data on the effects of a terminal Cretaceous event on the land flora, vegetation and climate. A previous study based on detailed sampling of leaves and their dispersed cuticle16 in the Raton Basin provides a framework for interpretation of other leaf sequences over 20 degrees of latitude. We conclude that at the boundary there were: (1) High levels of extinction in the south and low levels in the north; (2) major ecological disruption followed by long-term vegetational changes that mimicked normal ecological succession; (3) a major increase in precipitation; and (4) a brief, low-temperature excursion, which supports models of an 'impact winter'. ?? 1986 Nature Publishing Group.

22 CFR 1101.6 - Requests for access to records.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Requests for access to records. 1101.6 Section 1101.6 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.6 Requests for access to records. (a) Any individual may submit an inquiry to the Section to ascertain...

Astronomical calibration of Gauss to Matuyama sapropels in the Mediterranean and implication for the Geomagnetic Polarity Time Scale

NASA Astrophysics Data System (ADS)

Hilgen, F. J.

1991-06-01

The astronomically calibrated age of the Olduvai Subchron is established by correlating the cyclic sapropel patterns in the Vrica section and in the sections of Semaforo (Italy), Singa (Italy), Punta Piccola (Sicily), and Francocastello (Crete) to the new astronomical solutions for the precession of the equinox and eccentricity of the earth's orbit, using inferred phase relationships between the sapropel cycles and orbital cycles. The resultant ages for the Olduvai and for older boundaries are then compared with conventional, as well as other orbitally tuned ages, for these polarity transitions. It is shown that this astronomically calibrated time scale can be extended back to the Miocene/Pliocene boundary.

Characterisation of Ga-coated and Ga-brazed aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferchaud, E.; Christien, F., E-mail: frederic.christien@univ-nantes.fr; Barnier, V.

This work is devoted to the brazing of aluminium using liquid gallium. Gallium was deposited on aluminium samples at {approx} 50 Degree-Sign C using a liquid gallium 'polishing' technique. Brazing was undertaken for 30 min at 500 Degree-Sign C in air. EDS (Energy Dispersive X-ray Spectroscopy) and AES (Auger Electron Spectroscopy) characterisation of Ga-coated samples has shown that the Ga surface layer thickness is of ten (or a few tens of) nanometres. Furthermore, aluminium oxide layer (Al{sub 2}O{sub 3}) was shown to be 'descaled' during Ga deposition, which ensures good conditions for further brazing. Cross-section examination of Ga-coated samples showsmore » that liquid gallium penetrates into the aluminium grain boundaries during deposition. The thickness of the grain boundary gallium film was measured using an original EDS technique and is found to be of a few tens of nanometres. The depth of gallium grain boundary penetration is about 300 {mu}m at the deposition temperature. The fracture stress of the brazed joints was measured from tensile tests and was determined to be 33 MPa. Cross-section examination of brazed joints shows that gallium has fully dissolved into the bulk and that the joint is really autogenous. - Highlights: Black-Right-Pointing-Pointer Aluminium can be brazed using liquid gallium deposited by a 'polishing' technique. Black-Right-Pointing-Pointer The aluminium oxide layer is 'descaled' during liquid Ga 'polishing' deposition. Black-Right-Pointing-Pointer EDS can be used for determination of surface and grain boundary Ga film thickness. Black-Right-Pointing-Pointer The surface and grain boundary Ga film thickness is of a few tens of nm. Black-Right-Pointing-Pointer Surface and grain boundary gallium dissolves in the bulk during brazing.« less

22 CFR 1101.15 - Judicial review.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Judicial review. 1101.15 Section 1101.15 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.15 Judicial review. After having exhausted all administrative remedies set...

22 CFR 1104.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Purpose. 1104.1 Section 1104.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.1 Purpose. (a) The regulations in this part implement provisions of the...

22 CFR 1104.3 - Prohibited acts.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Prohibited acts. 1104.3 Section 1104.3 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.3 Prohibited acts. (a) No person may excavate, remove, damage...

22 CFR 1104.10 - Appeals relating to permits.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Appeals relating to permits. 1104.10 Section 1104.10 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.10 Appeals relating to permits. Any affected...

22 CFR 1104.5 - Application for permits and information collection.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Application for permits and information collection. 1104.5 Section 1104.5 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.5 Application for...

22 CFR 1104.14 - Assessment of civil penalties.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Assessment of civil penalties. 1104.14 Section 1104.14 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.14 Assessment of civil penalties. (a) The...

22 CFR 1104.3 - Prohibited acts.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Prohibited acts. 1104.3 Section 1104.3 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.3 Prohibited acts. (a) No person may excavate, remove, damage...

22 CFR 1101.15 - Judicial review.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Judicial review. 1101.15 Section 1101.15 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.15 Judicial review. After having exhausted all administrative remedies set...

22 CFR 1104.15 - Civil penalty amounts.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Civil penalty amounts. 1104.15 Section 1104.15 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.15 Civil penalty amounts. (a) Maximum amount of...

22 CFR 1101.10 - Accounting for disclosures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Accounting for disclosures. 1101.10 Section 1101.10 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.10 Accounting for disclosures. (a) Each system manager shall...

22 CFR 1104.9 - Suspension and revocation of permits.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Suspension and revocation of permits. 1104.9 Section 1104.9 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.9 Suspension and revocation of...

22 CFR 1101.15 - Judicial review.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Judicial review. 1101.15 Section 1101.15 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.15 Judicial review. After having exhausted all administrative remedies set...

22 CFR 1104.10 - Appeals relating to permits.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Appeals relating to permits. 1104.10 Section 1104.10 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.10 Appeals relating to permits. Any affected...

22 CFR 1101.10 - Accounting for disclosures.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Accounting for disclosures. 1101.10 Section 1101.10 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.10 Accounting for disclosures. (a) Each system manager shall...

22 CFR 1104.5 - Application for permits and information collection.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Application for permits and information collection. 1104.5 Section 1104.5 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.5 Application for...

Rock magnetism and magnetostratigraphy of the loess-sol series of Ukraine (Roksolany, Boyanychi, and Korshev sections)

NASA Astrophysics Data System (ADS)

Bakhmutov, V. G.; Kazanskii, A. Yu.; Matasova, G. G.; Glavatskii, D. V.

2017-11-01

The results of the rock magnetic and paleomagnetic studies for the Quaternary loess-sol deposits of Ukraine are reported. The magnetic properties of the rocks composing the sections in the Pre-Black-Sea Depression (Roksolany) and Volyn Upland (Boyanychi and Korshev) are compared. Based on the highly precise measurements by modern instruments, the primary magnetization component is isolated in the rocks and its polarity is reliably determined in both the loess and soil horizons. The position of the Matuyama-Brunhes boundary in the Roksolany section is determined at a depth of 46.6 m at the contact of the Lubenskii and Martonoshskii soil horizons. This is consistent with the present-day notions of the group of Ukrainian scientists about the Quaternary stratigraphy of the south of Ukraine and inconsistent with the previous results that placed this boundary at a depth of 34 m in loesses above the PK7 level.

The TORSED method for construction of TORT boundary sources from external DORT flux files

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhoades, W.A.

1993-08-01

The TORSED method provides a means of coupling cylindrical two-dimensional DORT fluxes or fluences to a three-dimensional TORT calculation in Cartesian geometry through construction of external boundary sources for TORT. This can be important for several reasons. The two-dimensional environment may be too large for TORT simulation. The two-dimensional environment may be truly cylindrical in nature, and thus, better treated in that geometry. It may be desired to use a single environment calculation to study numerous local perturbations. In Section I the TORSED code is described in detail and the diverse demonstration problems that accompany the code distribution are discussed.more » In Section II, an updated discussion of the VISA code is given. VISA is required to preprocess the DORT files for use in TORSED. In Section III, the references are listed.« less

Deviations from LTE in a stellar atmosphere

NASA Technical Reports Server (NTRS)

Kalkofen, W.; Klein, R. I.; Stein, R. F.

1979-01-01

Deviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.

Extinction cross-section suppression and active acoustic invisibility cloaking

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-10-01

Invisibility in its canonical form requires rendering a zero extinction cross-section (or energy efficiency) from an active or a passive object. This work demonstrates the successful theoretical realization of this physical effect for an active cylindrically radiating acoustic body, undergoing periodic axisymmetric harmonic vibrations near a flat rigid boundary. Radiating, amplification and extinction cross-sections of the active source are defined. Assuming monopole and dipole modal oscillations of the circular source, conditions are found where the extinction energy efficiency factor of the active source vanishes, achieving total invisibility with minimal influence of the source size. It also takes positive or negative values, depending on its size and distance from the boundary. Moreover, the amplification energy efficiency factor is negative for the acoustically-active source. These effects also occur for higher-order modal oscillations of the active source. The results find potential applications in the development of acoustic cloaking devices and invisibility.

Definition and Means of Maintaining the Emergency Notification and Evacuation System Portion of the Plutonium Finishing Plant (PFP) Safety Envelope

DOE Office of Scientific and Technical Information (OSTI.GOV)

WHITE, W.F.

2000-04-04

The purpose of this document is to provide the definition and means of maintaining the safety envelope (SE) for the Emergency Notification and Evacuation System (ENES). Together with the appendices, it provides: (1) The system requirements for determining system operability (Section 3.0); (2) Evaluations of equipment to determine the safety boundary for the system (Section 4.0); (3) List of system drawings that are annotated to show the SE boundaries (Appendix A); (4) Identification of the SE equipment by reference to systems and drawings (Appendix B); (5) Requirements for the individual SE equipment (Section 4.0); and (6) A list of themore » operational and surveillance procedures necessary to operate and maintain the system equipment within the SE (Sections 5.0 and 6.0). The Private Automatic Exchange (PAX) phones and PAX switchers are outside the safety envelope defined in WHC-SD-CP-OSR-010, Section 5.4.10, ''Safety Communication and Alarm Systems,'' Section 5.4.1 0.1, ''Major Components and Operating Characteristics,'' and Section 5.4.10.1.12, ''PAX System.'' The PAX override microphone system maintains the safety envelope, and functions as a backup to the evacuation sirens during an emergency.« less

Advanced Gradient Heating Facility (AGHF)

NASA Technical Reports Server (NTRS)

1998-01-01

This section of the publication includes papers entitled: (1) Coupled growth in hypermonotectics; (2) Directional solidification of refined Al-4 wt.% Cu alloys; (3) Effects of convection on interface curvature during growth of concentrated ternary compounds; (4) Directional solidification of Al-1.5 wt.% Ni alloys; (5) Interactive response of advancing phase boundaries to particles; (6) INTeractive Response of Advancing Phase boundaries to Particles-INTRAPP; and (7) Particle engulfment and pushing by solidifying interfaces.

An interactive multi-block grid generation system

NASA Technical Reports Server (NTRS)

Kao, T. J.; Su, T. Y.; Appleby, Ruth

1992-01-01

A grid generation procedure combining interactive and batch grid generation programs was put together to generate multi-block grids for complex aircraft configurations. The interactive section provides the tools for 3D geometry manipulation, surface grid extraction, boundary domain construction for 3D volume grid generation, and block-block relationships and boundary conditions for flow solvers. The procedure improves the flexibility and quality of grid generation to meet the design/analysis requirements.

Transit traverse in Missouri, 1900-1937. Part 6, Northeastern Missouri, 1900-37

USGS Publications Warehouse

Staack, John George

1940-01-01

This bulletin, which for convenience is to be published in eight parts, contains the results of all transit traverse* done In Missouri through 1937 by the Geological Survey, United States Department of the Interior, including those heretofore published. (See page X.) Each of the parts deals with one of eight sections into which the State has been divided for this purpose and which have been designated northeastern, northwestern, southeastern, southwestern, central, east-central, south-central, and west-central Missouri. In each part descriptions of the points for which geodetic positions have been determined are listed according to the quadrangles in which the points occur. Results of transit traverse other than that done by the Geological Survey have not been included.Northeastern Missouri, as the term is used in this bulletin and as the subject of part 6 of the bulletin, is, as its name indicates, the north-easternmost section of the State. Its north and east boundaries are the boundaries of the State; its west and south boundaries are formed by a line that runs south along longitude 93°15' to latitude 39°30', thence east to longitude 92°00', thence south to latitude 39°15', thence east to the east boundary of the State.

Active control of panel vibrations induced by a boundary layer flow

NASA Technical Reports Server (NTRS)

Chow, Pao-Liu

1995-01-01

The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to consider the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. Although the sound radiation has not been included, the vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings are presented in three sections. In section two we describe results on the boundary control of nonlinear panel vibration, with or without flow excitation. Sections three and four are concerned with some analytical and numerical results in the optimal control of the linear and nonlinear panel vibrations, respectively, excited by the flow pressure fluctuations. Finally, in section five, we draw some conclusions from research findings.

Timing of Neogene Manganese Deposit Formation in the Paleo-Japan Sea, northeast Japan

NASA Astrophysics Data System (ADS)

Ito, T.; Orihashi, Y.; Yanagisawa, Y.; Sakai, S.; Motoyama, I.; Kamikuri, S. I.; Komuro, K.; Suzuki, K.

2017-12-01

The generation ages of the two Neogene manganese deposits in northeast Japan were determined by diatom and radiolarian biostratigraphic analyses and zircon U-Pb dating. The manganese deposits analyzed were from the Kitaichi and Maruyama mines in the Fukaura district, northeast Japan. Manganese oxide layers of 0.5 m (Kitaichi) and 1.5 m (Maruyama) in thickness were predominantly composed of todorokite and occur conformably within volcanogenic sediments, which stratigraphically had correlated to middle Miocene in previous studies. The ages of the manganese oxide layers were 12.4 Ma. There was no time gap between the Kitaichi and the Maruyama manganese oxide layers, between the manganese oxide layer and the underlying tuffaceous sandstone in the Kitaichi mine, or within the manganese oxide layer of ca. 1.5 m thickness in the Maruyama mine. On the other hand, the overlying tuffaceous sandstone was dated at 4.5 Ma. The results suggest that the manganese oxide layers were formed immediately after the deposition of the tuffaceous sandstone at 12.4 Ma and that the restricted supply of volcanogenic and/or other detrital matter had kept for a long time (ca. 7 m.y.). The timing of the manganese deposit generation, 12.4 Ma, is identical to the age of the base of the Onnagawa Stage on the Nishikurosawa Stage in the Neogene stratotype section on the Japan Sea side, northeast Japan. And this is equivalent to the age of the start of diatom blooming. Paleogeographically, the manganese oxide deposition happened in a shallower area on a paleo-hill or a small island surrounded by stagnant mid to deep basins with diatom and organically carbon-rich, laminated, and fine-grained mud. It is highly probable that upwelling of mid to deep water rich in both dissolved manganese and nutrients is the trigger for the manganese deposit generation in shallower areas and the deposition of diatomaceous sediments in mid and deep basins. Eustatic regression might be the reason for the short-term formation of manganese deposits in shallower areas compared to continuous sedimentation ( several million years) of diatomaceous and organic carbon-rich mud in the surrounding mid to deep basins.

Newly combined 40Ar/39Ar and U-Pb ages of the Upper Cretaceous timescale from Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Gaylor, J. R.; Heredia, B. D.; Quidelleur, X.; Takashima, R.; Nishi, H.; Mezger, K.

2011-12-01

The main targets for GTS next project (www.gtsnext.eu) are to develop highly refined geological time scales, including the Upper Cretaceous. The Cretaceous period is characterised by numerous global anoxic events in the marine realm, rich ammonitic fossil assemblages and specialised foraminifera. However, lack of age diagnostic macro and micro fossils in the North Pacific sections has made it difficult to link these with global sections such as the Western Interior Basin (North America). Using advances with terrestrial C-isotope and planktic foraminifera records within Central Hokkaido we are able to correlate these sections globally. The Cretaceous Yezo group in Central Hokkaido comprises deep marine mudstones and turbidite sandstones interbedded with acidic volcanic tuffs. Using various sections within the Yezo group, we radiometrically dated tuffs at the main stage boundaries in the Upper Cretaceous. The samples derive from the Kotanbetsu, Shumarinai, Tiomiuchi and the Hakkin river sections, spanning the time from the Albian-Cenomanian up until the Campanian-Santonian boundaries, and were dated using 40Ar/39Ar, K/Ar and U-Pb techniques. Recent age constraints in the Hokkaido counterparts (Kotanbetsu sections) show good coherence between radiometric chronometers on the various Upper Cretaceous stage boundaries. These additional ages together with our isotope ages from the different sections around the Hokkaido basin are well linked by the various faunal assemblages and C-isotope curves. The combined radio isotope ages contribute to previous attempts (such as those focused in the Western Interior Basin) supporting the synchronicity of events such as global oceanic anoxic events. Finally, the ages obtained here also compliment the previous C-isotope and planktic foraminifera records allowing for a more precise climatic history of the Northwest Pacific during the Cretaceous. The research within the GTSnext project is funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement no. 215458.

Physical modeling of the atmospheric boundary layer in the UNH Flow Physics Facility

NASA Astrophysics Data System (ADS)

Taylor-Power, Gregory; Gilooly, Stephanie; Wosnik, Martin; Klewicki, Joe; Turner, John

2016-11-01

The Flow Physics Facility (FPF) at UNH has test section dimensions W =6.0m, H =2.7m, L =72m. It can achieve high Reynolds number boundary layers, enabling turbulent boundary layer, wind energy and wind engineering research with exceptional spatial and temporal instrument resolution. We examined the FPF's ability to experimentally simulate different types of the atmospheric boundary layer (ABL) using upstream roughness arrays. The American Society for Civil Engineers defines standards for simulating ABLs for different terrain types, from open sea to dense city areas (ASCE 49-12). The standards require the boundary layer to match a power law shape, roughness height, and power spectral density criteria. Each boundary layer type has a corresponding power law exponent and roughness height. The exponent and roughness height both increase with increasing roughness. A suburban boundary layer was chosen for simulation and a roughness element fetch was created. Several fetch lengths were experimented with and the resulting boundary layers were measured and compared to standards in ASCE 49-12: Wind Tunnel Testing for Buildings and Other Structures. Pitot tube and hot wire anemometers were used to measure average and fluctuating flow characteristics. Velocity profiles, turbulence intensity and velocity spectra were found to compare favorably.

The behavior of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient. Ph.D. Thesis - Washington Univ., Seattle, Aug. 1972

NASA Technical Reports Server (NTRS)

Rose, W. C.

1973-01-01

The results of an experimental investigation of the mean- and fluctuating-flow properties of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient are presented. The turbulent boundary layer developed on the wall of an axially symmetric nozzle and test section whose nominal free-stream Mach number and boundary-layer thickness Reynolds number were 4 and 100,000, respectively. The adverse pressure gradient was induced by an externally generated conical shock wave. Mean and time-averaged fluctuating-flow data, including the complete experimental Reynolds stress tensor and experimental turbulent mass- and heat-transfer rates are presented for the boundary layer and external flow, upstream, within and downstream of the pressure gradient. The mean-flow data include distributions of total temperature throughout the region of interest. The turbulent mixing properties of the flow were determined experimentally with a hot-wire anemometer. The calibration of the wires and the interpretation of the data are discussed. From the results of the investigation, it is concluded that the shock-wave - boundary-layer interaction significantly alters the turbulent mixing characteristics of the boundary layer.

Identification and characterization of adolescents' sexual boundaries.

PubMed

Wolf, Hilary T; Morrell, Holly E R; Halpern-Felsher, Bonnie L

2013-07-01

Adolescents' decisions to have sex may be based on a priori boundaries placed on sex. This study addresses: (1) to what extent adolescents set vaginal sexual boundaries; (2) the types of sexual boundaries most and least likely to be endorsed; and (3) to what extent sexual boundaries vary by sex, race/ethnicity, and sexual experience. A cross-sectional study of 518 students attending 10th grade. Survey measures queried about demographics, ever having sex, and existence of sexual boundaries (e.g., being in love, having an attractive partner) that must be in place before having vaginal sex. The most frequently endorsed boundaries were maturity, commitment, trust, love, and marriage. These boundaries were more frequently endorsed than having a safer-sex method. Compared with females, males were more likely to choose boundaries based on partner attractiveness (p < .001) and avoiding trouble (p < .04). Compared with Asians and Pacific Islanders, whites were more likely to endorse wanting to be a certain age to have sex (p < .01 and p < .05, respectively); Asians and Pacific Islanders were more likely to choose sexual boundaries based on marriage (p's < .05). Adolescents who were sexually experienced were more likely than inexperienced adolescents to endorse boundaries related to relationship characteristics and partner attractiveness (OR = 2.5), and less likely to endorse boundaries related to feeling mature (OR = .34) and waiting until marriage (OR = .34). Identifying adolescents' sexual boundaries should help healthcare professionals better understand under what circumstances adolescents are more or less likely to have sex; and this information should ultimately inform the development of new interventions. Copyright © 2013 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

10 CFR 50.55a - Codes and standards.

Code of Federal Regulations, 2012 CFR

2012-01-01

... commitments must be applied to Section XI activities. (xi) [Reserved] (xii) Underwater welding. The provisions in IWA-4660, “Underwater Welding,” of Section XI, 1997 Addenda through the latest edition and addenda... performed by welding or brazing on a pressure retaining boundary using the 2003 Addenda through the latest...

10 CFR 50.55a - Codes and standards.

Code of Federal Regulations, 2013 CFR

2013-01-01

... commitments must be applied to Section XI activities. (xi) [Reserved] (xii) Underwater welding. The provisions in IWA-4660, “Underwater Welding,” of Section XI, 1997 Addenda through the latest edition and addenda... performed by welding or brazing on a pressure retaining boundary using the 2003 Addenda through the latest...

50 CFR 660.78 - EFH Conservation Areas off the Coast of Oregon.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Oregon. 660.78 Section 660.78 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... West Coast Groundfish Fisheries § 660.78 EFH Conservation Areas off the Coast of Oregon. Boundary line coordinates for EFH Conservation Areas off Oregon are provided in this section. Fishing activity that is...

50 CFR 660.78 - EFH Conservation Areas off the Coast of Oregon.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Oregon. 660.78 Section 660.78 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... West Coast Groundfish Fisheries § 660.78 EFH Conservation Areas off the Coast of Oregon. Boundary line coordinates for EFH Conservation Areas off Oregon are provided in this section. Fishing activity that is...

50 CFR 660.78 - EFH Conservation Areas off the Coast of Oregon.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Oregon. 660.78 Section 660.78 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... West Coast Groundfish Fisheries § 660.78 EFH Conservation Areas off the Coast of Oregon. Boundary line coordinates for EFH Conservation Areas off Oregon are provided in this section. Fishing activity that is...

22 CFR 1101.16 - Criminal penalties.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Criminal penalties. 1101.16 Section 1101.16 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.16 Criminal penalties. (a) Under the provisions of the Act, it is a...

22 CFR 1102.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Purpose. 1102.1 Section 1102.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.1 Purpose. The purpose of this part is to prescribe rules, guidelines and procedures to...

22 CFR 1102.4 - Fees.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Fees. 1102.4 Section 1102.4 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.4 Fees. (a) The following shall be applicable with respect to services rendered to...

22 CFR 1101.9 - Exemptions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Exemptions. 1101.9 Section 1101.9 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.9 Exemptions. The following are exempt from disclosure under 5 U.S.C. 552a (j...

22 CFR 1101.1 - Purpose and scope.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Purpose and scope. 1101.1 Section 1101.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.1 Purpose and scope. The purpose of these regulations is to prescribe...

22 CFR 1102.10 - Examination of records.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Examination of records. 1102.10 Section 1102.10 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.10 Examination of records. When a request to examine records is...

22 CFR 1104.8 - Terms and conditions of permits.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Terms and conditions of permits. 1104.8 Section 1104.8 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.8 Terms and conditions of permits. (a) In...

27 CFR 9.172 - West Elks.

Code of Federal Regulations, 2014 CFR

2014-04-01

... W.); (1) The boundary proceeds east following the center subdivision lines of Sections 20 and 21 to its intersection with Colorado Highway 133; (2) Then northeasterly following Colorado Highway 133 to its intersection with the N-S center subdivision line of Section 14, T. 13 S., R. 91 W., near Juanita...

27 CFR 9.172 - West Elks.

Code of Federal Regulations, 2011 CFR

2011-04-01

... W.); (1) The boundary proceeds east following the center subdivision lines of Sections 20 and 21 to its intersection with Colorado Highway 133; (2) Then northeasterly following Colorado Highway 133 to its intersection with the N-S center subdivision line of Section 14, T. 13 S., R. 91 W., near Juanita...

27 CFR 9.172 - West Elks.

Code of Federal Regulations, 2013 CFR

2013-04-01

... W.); (1) The boundary proceeds east following the center subdivision lines of Sections 20 and 21 to its intersection with Colorado Highway 133; (2) Then northeasterly following Colorado Highway 133 to its intersection with the N-S center subdivision line of Section 14, T. 13 S., R. 91 W., near Juanita...

27 CFR 9.172 - West Elks.

Code of Federal Regulations, 2012 CFR

2012-04-01

... W.); (1) The boundary proceeds east following the center subdivision lines of Sections 20 and 21 to its intersection with Colorado Highway 133; (2) Then northeasterly following Colorado Highway 133 to its intersection with the N-S center subdivision line of Section 14, T. 13 S., R. 91 W., near Juanita...

27 CFR 9.172 - West Elks.

Code of Federal Regulations, 2010 CFR

2010-04-01

... W.); (1) The boundary proceeds east following the center subdivision lines of Sections 20 and 21 to its intersection with Colorado Highway 133; (2) Then northeasterly following Colorado Highway 133 to its intersection with the N-S center subdivision line of Section 14, T. 13 S., R. 91 W., near Juanita...

22 CFR 1102.8 - Exemptions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Exemptions. 1102.8 Section 1102.8 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.8 Exemptions. (a) 5 U.S.C. 552(b) provides that the requirements of the...

22 CFR 1101.16 - Criminal penalties.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Criminal penalties. 1101.16 Section 1101.16 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.16 Criminal penalties. (a) Under the provisions of the Act, it is a...

22 CFR 1101.16 - Criminal penalties.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Criminal penalties. 1101.16 Section 1101.16 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.16 Criminal penalties. (a) Under the provisions of the Act, it is a...

22 CFR 1101.9 - Exemptions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Exemptions. 1101.9 Section 1101.9 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.9 Exemptions. The following are exempt from disclosure under 5 U.S.C. 552a (j...

22 CFR 1101.1 - Purpose and scope.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Purpose and scope. 1101.1 Section 1101.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.1 Purpose and scope. The purpose of these regulations is to prescribe...

22 CFR 1101.1 - Purpose and scope.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Purpose and scope. 1101.1 Section 1101.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.1 Purpose and scope. The purpose of these regulations is to prescribe...

22 CFR 1102.1 - Purpose.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Purpose. 1102.1 Section 1102.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.1 Purpose. The purpose of this part is to prescribe rules, guidelines and procedures to...

22 CFR 1102.5 - Categories of requesters for fee purposes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Categories of requesters for fee purposes. 1102.5 Section 1102.5 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.5 Categories of requesters for fee...

22 CFR 1101.9 - Exemptions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Exemptions. 1101.9 Section 1101.9 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.9 Exemptions. The following are exempt from disclosure under 5 U.S.C. 552a (j...

22 CFR 1102.1 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Purpose. 1102.1 Section 1102.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION FREEDOM OF INFORMATION ACT § 1102.1 Purpose. The purpose of this part is to prescribe rules, guidelines and procedures to...

22 CFR 1101.1 - Purpose and scope.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Purpose and scope. 1101.1 Section 1101.1 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.1 Purpose and scope. The purpose of these regulations is to prescribe...

22 CFR 1104.8 - Terms and conditions of permits.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Terms and conditions of permits. 1104.8 Section 1104.8 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.8 Terms and conditions of permits. (a) In...

22 CFR 1102.8 - Exemptions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Exemptions. 1102.8 Section 1102.8 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION...) Requires that the matters be withheld from the public in such a manner as to leave no discretion on the...

Influence of a heated leading edge on boundary layer growth, stability, and transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landrum, D.B.; Macha, J.M.

1987-06-01

This paper presents the results of a combined theoretical and experimental study of the influence of a heated leading edge on the growth, stability, and transition of a two-dimensional boundary layer. The findings are directly applicable to aircraft wings and nacelles that use surface heating for anti-icing protection. The potential effects of the non-adiabatic condition are particularly important for laminar-flow sections where even small perturbations can result in significantly degraded aerodynamic performance. The results of the study give new insight to the fundamental coupling between streamwise pressure gradient and surface heat flux in laminar and transitional boundary layers. 13 references.

Influence of a heated leading edge on boundary layer growth, stability, and transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landrum, D.B.; Macha, J.M.

1987-01-01

This paper presents the results of a combined theoretical and experimental study of the influence of a heated leading edge on the growth, stability, and transition of a two-dimensional boundary layer. The findings are directly applicable to aircraft wings and nacelles that use surface heating for anti-icing protection. The potential effects of the non-adiabatic condition are particularly important for laminar-flow sections where even small perturbations can result in significantly degraded aerodynamic performance. The results of the study give new insight to the fundamental coupling between streamwise pressure gradient and surface heat flux in laminar and transitional boundary layers.

Cooling History of Almahata Sitta Ureilite as Inferred from Transmission Electron Microscopy of Iron Metal

NASA Technical Reports Server (NTRS)

Mikouchi, T.; Aoyagi, Y.; Goodrich, C. A.; Yubuta, K.; Sugiyama, K.; Zolensky, M. E.; Goldstein, J. I.

2013-01-01

Almahata Sitta (AS) is a polymict breccia mainly composed of various ureilite lithologies with lesser chondritic lithologies [1]. In the ureilite lithologies, Fe metal is a common accessory phase present either as large grain boundary grains or small particles formed by reduction of olivine and pyroxene. In our earlier studies on grain boundary metals in one of AS fragments (#44) we found unique features never seen in other ureilites [2,3]. In order to further characterize these metal grains, we performed a detailed TEM study on a FIB section prepared from one of AS #44 grain boundary metals and here discuss its thermal history.

High-resolution leaf-fossil record spanning the Cretaceous/Tertiary boundary

USGS Publications Warehouse

Johnson, K.R.; Nichols, D.J.; Attrep, M.; Orth, C.J.

1989-01-01

THEORIES that explain the extinctions characterizing the Cretaceous/Tertiary (K/T) boundary1-3 need to be tested by analyses of thoroughly sampled biotas. Palynological studies are the primary means for stratigraphic placement of the terrestrial boundary and for estimates of plant extinction4-12, but have not been combined with quantitative analyses of fossil leaves (megaflora). Megafloral studies complement palynology by representing local floras with assemblages capable of high taxonomic resolution13, but have previously lacked the sample size and stratigraphic spacing needed to resolve latest Cretaceous floral history5,14-18. We have now combined megafloral data from a 100-m-thick composite K/T boundary section in North Dakota with detailed palynological analysis. Here the boundary is marked by a 30% palynofloral extinction coincident with iridium and shocked-mineral anomalies and lies ???2 m above the highest dinosaur remains. The megaflora undergoes a 79% turnover across the boundary, and smaller changes 17- and 25-m below it. This pattern is consistent with latest Cretaceous climatic warming preceding a bolide impact. ?? 1989 Nature Publishing Group.

Development of an integrated BEM approach for hot fluid structure interaction

NASA Technical Reports Server (NTRS)

Dargush, Gary F.; Banerjee, Prasanta K.; Honkala, Keith A.

1991-01-01

The development of a boundary element formulation for the study of hot fluid-structure interaction in earth-to-orbit engine hot section components is described. The initial primary thrust of the program to date was directed quite naturally toward the examination of fluid flow, since boundary element methods for fluids are at a much less developed state. This required the development of integral formulations for both the solid and fluid, and some preliminary infrastructural enhancements to a boundary element code to permit coupling of the fluid-structure problem. Boundary element formulations are implemented in two dimensions for both the solid and the fluid. The solid is modeled as an uncoupled thermoelastic medium under plane strain conditions, while several formulations are investigated for the fluid. For example, both vorticity and primitive variable approaches are implemented for viscous, incompressible flow, and a compressible version is developed. All of the above boundary element implementations are incorporated in a general purpose two-dimensional code. Thus, problems involving intricate geometry, multiple generic modeling regions, and arbitrary boundary conditions are all supported.

Quantum gravity in three dimensions, Witten spinors and the quantisation of length

NASA Astrophysics Data System (ADS)

Wieland, Wolfgang

2018-05-01

In this paper, I investigate the quantisation of length in euclidean quantum gravity in three dimensions. The starting point is the classical hamiltonian formalism in a cylinder of finite radius. At this finite boundary, a counter term is introduced that couples the gravitational field in the interior to a two-dimensional conformal field theory for an SU (2) boundary spinor, whose norm determines the conformal factor between the fiducial boundary metric and the physical metric in the bulk. The equations of motion for this boundary spinor are derived from the boundary action and turn out to be the two-dimensional analogue of the Witten equations appearing in Witten's proof of the positive mass theorem. The paper concludes with some comments on the resulting quantum theory. It is shown, in particular, that the length of a one-dimensional cross section of the boundary turns into a number operator on the Fock space of the theory. The spectrum of this operator is discrete and matches the results from loop quantum gravity in the spin network representation.

Pressure-sensing performance of upright cylinders in a Mach 10 boundary-layer

NASA Technical Reports Server (NTRS)

Johnson, Steven; Murphy, Kelly

1994-01-01

An experimental research program to provide basic knowledge of the pressure-sensing performance of upright, flushported cylinders in a hypersonic boundary layer is described. Three upright cylinders of 0.25-, 0.5- and l.0-in. diameters and a conventional rake were placed in the test section sidewall boundary layer of the 31 Inch Mach 10 Wind Tunnel at NASA Langley Research Center, Hampton, Virginia. Boundary-layer pressures from these cylinders were compared to those measured with a conventional rake. A boundary-layer thickness-to-cylinder-diameter ratio of 8 proved sufficient to accurately measure an overall pressure profile and ascertain the boundary-layer thickness. Effects of Reynolds number, flow angularity, and shock wave impingement on pressure measurement were also investigated. Although Reynolds number effects were negligible at the conditions studied, flow angularity above 10 deg significantly affects the measured pressures. Shock wave impingement was used to investigate orifice-to-orifice pressure crosstalk. No crosstalk was measured. The lower pressure measured above the oblique shock wave impingement showed no influence of the higher pressure generated at the lower port locations.

Three-dimensional transformation optics for arbitrary coordinate systems: transforming conductive materials and boundaries.

PubMed

Kazemzadeh, Mohammad-Rahim; Alighanbari, Abbas

2018-04-16

A three-dimensional transformation optics method, leading to homogeneous materials, applicable to any non-Cartesian coordinate systems or waveguides/objects of arbitrary cross-sections is presented. Both the conductive boundary and internal material of the desired device is determined by the proposed formulation. The method is applicable to a wide range of waveguide, radiation, and cloaking problems, and is demonstrated for circular waveguide couplers and an external cloak. An advantage of the present method is that the material properties are simplified by appropriately selecting the conductive boundaries. For instance, a right-angle circular waveguide bend is presented which uses only one homogenous material. Also, transformation of conductive materials and boundaries are studied. The conditions in which the transformed boundaries remain conductive are discussed. In addition, it is demonstrated that negative infinite conductivity can be replaced with positive conductivity, without affecting the field outside the conductive boundary. It is also observed that a negative finite conductivity can be replaced with a positive one, by accepting some small errors. The general mathematical procedure and formulation for calculating the parametric surface equations of the conductive peripheries are presented.

A multistratigraphic approach to pinpoint the Permian-Triassic boundary in continental deposits: The Zechstein-Lower Buntsandstein transition in Germany

NASA Astrophysics Data System (ADS)

Scholze, Frank; Wang, Xu; Kirscher, Uwe; Kraft, Johannes; Schneider, Jörg W.; Götz, Annette E.; Joachimski, Michael M.; Bachtadse, Valerian

2017-05-01

The Central European Basin is very suitable for high-resolution multistratigraphy of Late Permian to Early Triassic continental deposits. Here the well exposed continuous transition of the lithostratigraphic Zechstein and Buntsandstein Groups of Central Germany was studied for isotope-chemostratigraphy (δ13Corg, δ13Ccarb, δ18Ocarb), major and trace element geochemistry, magnetostratigraphy, palynology, and conchostracan biostratigraphy. The analysed material was obtained from both classical key sections (abandoned Nelben clay pit, Caaschwitz quarries, Thale railway cut, abandoned Heinebach clay pit) and a recent drill core section (Caaschwitz 6/2012) spanning the Permian-Triassic boundary. The Zechstein-Buntsandstein transition of Central Germany consists of a complex sedimentary facies comprising sabkha, playa lake, aeolian, and fluvial deposits of predominantly red-coloured siliciclastics and intercalations of lacustrine oolitic limestones. The new data on δ13Corg range from - 28.7 to - 21.7 ‰ showing multiple excursions. Most prominent negative shifts correlate with intercalations of oolites and grey-coloured clayey siltstones, while higher δ13Corg values correspond to an onset of palaeosol overprint. The δ13Ccarb values range from - 9.7 to - 1.3 ‰ with largest variations recorded in dolomitic nodules from the Zechstein Group. In contrast to sedimentary facies shifts across the Zechstein-Buntsandstein boundary, major element values used as a proxy (CIA, CIA*, CIA-K) for weathering conditions indicate climatic stability. Trace element data used for a geochemical characterization of the Late Permian to Early Triassic transition in Central Germany indicate a decrease in Rb contents at the Zechstein-Buntsandstein boundary. New palynological data obtained from the Caaschwitz quarry section reveal occurrences of Late Permian palynomorphs in the Lower Fulda Formation, while Early Triassic elements were recorded in the upper part of the Upper Fulda Formation. The present study confirms an onset of a normal-polarized magnetozone in the Upper Fulda Formation of the Caaschwitz quarry section supporting an interregional correlation of this crucial stratigraphic interval with the normal magnetic polarity of the basal Early Triassic known from marine sections in other regions. Based on a synthesis of the multistratigraphic data, the Permian-Triassic boundary is proposed to be placed in the lower part of the Upper Fulda Formation, which is biostratigraphically confirmed by the first occurrence date of the Early Triassic Euestheria gutta-Palaeolimnadiopsis vilujensis conchostracan fauna. Rare records of conchostracans reported from the siliciclastic deposits of the lower to middle Zechstein Group may point to its potential for further biostratigraphic subdivision of the Late Permian continental deposits.

The long way of planktonic Foraminifera from biostratigraphy to paleoceanography (Jean Baptiste Lamarck Medal Lecture)

NASA Astrophysics Data System (ADS)

Premoli Silva, Isabella

2014-05-01

The mid of the last century was a time of flourishing studies concerning the importance of planktonic foraminifera in precisely dating and correlating sedimentary successions after the publication of the first biostratigraphic schemes provided by the Suisse Group (i.e. Kugler, Bolli, Broennimann) from the Caribbean region and former Southern USSR (Subbotina). Soon after Bolli's Trinidad scheme was widespread, planktonic foraminiferal distribution from Upper Cretaceous to Miocene was investigated intensively for dating the Neogene stratotypes, whose identifications were mainly based on poorly age-diagnostic, facies-controlled macrofossils, and for calibrating Paleogene larger foraminiferal distributions. Since these early works planktonic foraminiferal biostratigraphy was continously ameliorated, extended in time from Early Cretaceous to Recent by several authors and from different settings and domains, reaching progressively the current higher resolution, now calibrated to calcareous nannofossil distributions. To be mentioned, the detailed biostratigraphic studies on the Gubbio section (central Italy) provided (1) the first carefull documentation of the mass extinction of Cretaceous planktonic foraminifera, the presence of tiny Cretaceous survivors, and the rapid recovery of Danian assemblages, and (2) the first calibration of the Upper Cretaceous to Eocene reversal polarity scale in which the K/Pg boundary was demonstrated to fall within the magnetic reversal C29r. A major step forward was the recovery, since 1968, of several thousand of cores from over 1000 holes drilled in all oceans by the DSDP, ODP and IODP projects. The recovery of deep-sea sediments from all latitudes opened a new research field, the paleoceanography. Based on the large knowledge acquired on modern organisms in the '60s, for the Paleogene and Cretaceous reconstructions we started from the assumption that these extinct organisms lived in the water column like their modern counterpart and were controlled by similar environmental factors (temperature, nutrient supply, current system, etc.), then the fluctuations in abundance and composition of planktonic foraminiferal assemblages could be interpreted in term of paleobiogeography and paleoceanography. The first studies, rigorously quantitative, have been conducted in the '70s on the Paleogene of the Atlantic Ocean, the interval with the best latitudinal coverage at that time. From the areal distribution and variations in assemblage composition through time we (with A. Boersma) were able to identify first the biogeographic indices, then their paleoclimatic significances, from which we could reconstruct the paleoclimatic and paleoceanographic evolution. The associated isotope analyses (with N. Shackleton) on single species allowed to confirm the species latitudinal connotations as well as their position within the water column (mixed layer vs deep dwelling habitats) and preferences for nutrient supply. In the '90s we (with W.V. Sliter) extended the paleoceanographic reconstructions to the Cretaceous exploring the planktonic foraminiferal evolutionary patterns and latitudinal changes in assemblage composition through time. Like in the Paleogene, it was possibile to identify that the more ornamented keeled forms were very sensitive to temperature, liked warm waters and were more abundant in the tropics, the simpler morphologies were less sensitive, more tolerant and cosmopolitan, while, for instance, whiteinellids proliferated in upwelling regions. In the last decade, taking advantage of the wealth of paleoecological and biogeographical data previously collected, we started a new phase of deep taxonomical and stratigraphical revision of planktonic foraminifera. Increased biostratigraphic resolution from tropics to high latitudes is facilitated by the integration with other fossil group biostratigraphies and magneto-, isotope-stratigraphies.

Digital floodplain mapping and an analysis of errors involved

USGS Publications Warehouse

Hamblen, C.S.; Soong, D.T.; Cai, X.

2007-01-01

Mapping floodplain boundaries using geographical information system (GIS) and digital elevation models (DEMs) was completed in a recent study. However convenient this method may appear at first, the resulting maps potentially can have unaccounted errors. Mapping the floodplain using GIS is faster than mapping manually, and digital mapping is expected to be more common in the future. When mapping is done manually, the experience and judgment of the engineer or geographer completing the mapping and the contour resolution of the surface topography are critical in determining the flood-plain and floodway boundaries between cross sections. When mapping is done digitally, discrepancies can result from the use of the computing algorithm and digital topographic datasets. Understanding the possible sources of error and how the error accumulates through these processes is necessary for the validation of automated digital mapping. This study will evaluate the procedure of floodplain mapping using GIS and a 3 m by 3 m resolution DEM with a focus on the accumulated errors involved in the process. Within the GIS environment of this mapping method, the procedural steps of most interest, initially, include: (1) the accurate spatial representation of the stream centerline and cross sections, (2) properly using a triangulated irregular network (TIN) model for the flood elevations of the studied cross sections, the interpolated elevations between them and the extrapolated flood elevations beyond the cross sections, and (3) the comparison of the flood elevation TIN with the ground elevation DEM, from which the appropriate inundation boundaries are delineated. The study area involved is of relatively low topographic relief; thereby, making it representative of common suburban development and a prime setting for the need of accurately mapped floodplains. This paper emphasizes the impacts of integrating supplemental digital terrain data between cross sections on floodplain delineation. ?? 2007 ASCE.

Reconstruction of 3d grain boundaries from rock thin sections, using polarised light

NASA Astrophysics Data System (ADS)

Markus Hammes, Daniel; Peternell, Mark

2016-04-01

Grain boundaries affect the physical and chemical properties of polycrystalline materials significantly by initiating reactions and collecting impurities (Birchenall, 1959), and play an essential role in recrystallization (Doherty et al. 1997). In particular, the shape and crystallographic orientation of grain boundaries reveal the deformation and annealing history of rocks (Kruhl and Peternell 2002, Kuntcheva et al. 2006). However, there is a lack of non-destructive and easy-to-use computer supported methods to determine grain boundary geometries in 3D. The only available instrument using optical light to measure grain boundary angles is still the polarising microscope with attached universal stage; operated manually and time-consuming in use. Here we present a new approach to determine 3d grain boundary orientations from 2D rock thin sections. The data is recorded by using an automatic fabric analyser microscope (Peternell et al., 2010). Due to its unique arrangement of 9 light directions the highest birefringence colour due to each light direction and crystal orientation (retardation) can be determined at each pixel in the field of view. Retardation profiles across grain boundaries enable the calculation of grain boundary angle and direction. The data for all positions separating the grains are combined and further processed. In combination with the lateral position of the grain boundary, acquired using the FAME software (Hammes and Peternell, in review), the data is used to reconstruct a 3d grain boundary model. The processing of data is almost fully automatic by using MATLAB®. Only minor manual input is required. The applicability was demonstrated on quartzite samples, but the method is not solely restricted on quartz grains and other birefringent polycrystalline materials could be used instead. References: Birchenall, C.E., 1959: Physical Metallurgy. McGraw-Hill, New York. Doherty, R.D., Hughes, D.A., Humphreys, F.J., Jonas, J.J., Juul Jensen, D., Kassner, M.E., King, W.E., McNelley, T.R., McQueen, H.J., Rollett, A.D., 1997: Current issues in recrystallization: a review. Materials Science and Engineering A 238, 219-274. Hammes, D.M., Peternell, M., in review. FAME: Software for analysing rock microstructures. Computers & Geoscience. Kruhl, J.H., Peternell, M., 2002. The equilibration of high-angle grain boundaries in dynamically recrystallized quartz: the effect of crystallography and temperature. Journal of Structural Geology 24, 1125-1137. Kuntcheva, B., Kruhl, J.H. & Kunze, K., 2006. Crystallographic orientation of high-angle grain boundaries in dynamically recrystallized quartz: First results. Tectonophysics 421, 331-346. Peternell, M., Hasalová, P., Wilson, J.L., Piaziolo, S., Schulmann, K., 2010. Evaluating quartz crystallographic preferred orientations and the role of deformation partitioning using EBSD and fabric analyser techniques. Journal of Structural Geology 32, 803-817.

A design method for entrance sections of transonic wind tunnels with rectangular cross sections

NASA Technical Reports Server (NTRS)

Lionel, L.; Mcdevitt, J. B.

1975-01-01

A mathematical technique developed to design entrance sections for transonic or high-speed subsonic wind tunnels with rectangular cross sections is discribed. The transition from a circular cross-section setting chamber to a rectangular test section is accomplished smoothly so as not to introduce secondary flows (vortices or boundary-layer separation) into a uniform test stream. The results of static-pressure measurements in the transition region and of static and total-pressure surveys in the test section of a pilot model for a new facility at the Ames Research Center are presented.

Santa Margarita Lagoon Water Quality Monitoring Data

DTIC Science & Technology

2012-08-01

sits entirely within the boundaries of Marine Corps Base Camp Pendleton. It forms up where the Santa Margarita River meets the Pacific Ocean just north...of Oceanside, California. The western boundary of the lagoon is the beach berm that borders the ocean . The estuarine lagoon is usually open to the... ocean through a limited section of berm, although there are occasions when the lagoon is effectively closed to exchange with the ocean . The eastern

Free Vibrations of Nonthin Elliptic Cylindrical Shells of Variable Thickness

NASA Astrophysics Data System (ADS)

Grigorenko, A. Ya.; Efimova, T. L.; Korotkikh, Yu. A.

2017-11-01

The problem of the free vibrations of nonthin elliptic cylindrical shells of variable thickness under various boundary conditions is solved using the refined Timoshenko-Mindlin theory. To solve the problem, an effective numerical approach based on the spline-approximation and discrete-orthogonalization methods is used. The effect of the cross-sectional shape, thickness variation law, material properties, and boundary conditions on the natural frequency spectrum of the shells is analyzed.

Role of Grain Boundaries under Long-Time Radiation

NASA Astrophysics Data System (ADS)

Zhu, Yichao; Luo, Jing; Guo, Xu; Xiang, Yang; Chapman, Stephen Jonathan

2018-06-01

Materials containing a high proportion of grain boundaries offer significant potential for the development of radiation-resistant structural materials. However, a proper understanding of the connection between the radiation-induced microstructural behavior of a grain boundary and its impact at long natural time scales is still missing. In this Letter, point defect absorption at interfaces is summarized by a jump Robin-type condition at a coarse-grained level, wherein the role of interface microstructure is effectively taken into account. Then a concise formula linking the sink strength of a polycrystalline aggregate with its grain size is introduced and is well compared with experimental observation. Based on the derived model, a coarse-grained formulation incorporating the coupled evolution of grain boundaries and point defects is proposed, so as to underpin the study of long-time morphological evolution of grains induced by irradiation. Our simulation results suggest that the presence of point defect sources within a grain further accelerates its shrinking process, and radiation tends to trigger the extension of twin boundary sections.

Principal Eigenvalue Minimization for an Elliptic Problem with Indefinite Weight and Robin Boundary Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hintermueller, M., E-mail: hint@math.hu-berlin.de; Kao, C.-Y., E-mail: Ckao@claremontmckenna.edu; Laurain, A., E-mail: laurain@math.hu-berlin.de

2012-02-15

This paper focuses on the study of a linear eigenvalue problem with indefinite weight and Robin type boundary conditions. We investigate the minimization of the positive principal eigenvalue under the constraint that the absolute value of the weight is bounded and the total weight is a fixed negative constant. Biologically, this minimization problem is motivated by the question of determining the optimal spatial arrangement of favorable and unfavorable regions for a species to survive. For rectangular domains with Neumann boundary condition, it is known that there exists a threshold value such that if the total weight is below this thresholdmore » value then the optimal favorable region is like a section of a disk at one of the four corners; otherwise, the optimal favorable region is a strip attached to the shorter side of the rectangle. Here, we investigate the same problem with mixed Robin-Neumann type boundary conditions and study how this boundary condition affects the optimal spatial arrangement.« less

Stratigraphy and sedimentology of the K/T boundary deposit in Haiti

NASA Technical Reports Server (NTRS)

Carey, S.; Sigurdsson, H.; Dhondt, S.; Espindola, J. M.

1993-01-01

The K/T boundary sequence is exposed in uplifted carbonate sediments of the southwest peninsula of Haiti. It is found at 15 localities within the Beloc formation, a sequence of limestone and marls interpreted as a monoclinal nappe structure thrust to the north. This tectonic deformation has affected the K/T boundary deposit to varying degrees. In some cases the less competent K/T deposit has acted as a slip plane leading to extensive shearing of the boundary layer, as well as duplication of the section. The presence of glassy tektites, shocked quartz, and an Ir anomaly directly link the deposit to a bolide impact. Stratigraphic and sedimentological features of the tripartite sequence indicate that it was formed by deposition from ballistic fallout of coarse tektites, emplacement of particle gravity flows and fine grained fallout of widely dispersed impact ejecta.

Optimization of bump and blowing to control the flow through a transonic compressor blade cascade

NASA Astrophysics Data System (ADS)

Mazaheri, K.; Khatibirad, S.

2018-03-01

Shock control bump (SCB) and blowing are two flow control methods, used here to improve the aerodynamic performance of transonic compressors. Both methods are applied to a NASA rotor 67 blade section and are optimized to minimize the total pressure loss. A continuous adjoint algorithm is used for multi-point optimization of a SCB to improve the aerodynamic performance of the rotor blade section, for a range of operational conditions around its design point. A multi-point and two single-point optimizations are performed in the design and off-design conditions. It is shown that the single-point optimized shapes have the best performance for their respective operating conditions, but the multi-point one has an overall better performance over the whole operating range. An analysis is given regarding how similarly both single- and multi-point optimized SCBs change the wave structure between blade sections resulting in a more favorable flow pattern. Interactions of the SCB with the boundary layer and the wave structure, and its effects on the separation regions are also studied. We have also introduced the concept of blowing for control of shock wave and boundary-layer interaction. A geometrical model is introduced, and the geometrical and physical parameters of blowing are optimized at the design point. The performance improvements of blowing are compared with the SCB. The physical interactions of SCB with the boundary layer and the shock wave are analyzed. The effects of SCB on the wave structure in the flow domain outside the boundary-layer region are investigated. It is shown that the effects of the blowing mechanism are very similar to the SCB.

The Mars Crustal Magnetic Field Control of Plasma Boundary Locations and Atmospheric Loss: MHD Prediction and Comparison with MAVEN

NASA Technical Reports Server (NTRS)

Fang, Xiaohua; Ma, Yingjuan; Masunaga, Kei; Dong, Chuanfei; Brain, David; Halekas, Jasper; Lillis, Robert; Jakosky, Bruce M.; Connerney, Jack; Grebowsky, Joseph;

Rapid Shifts in Oxygen and Hydrogen Isotopes, and Chemical Components in Pore Waters During mid-Oligocene in Sediments from IODP 351drilling

NASA Astrophysics Data System (ADS)

Zhang, Z.

2017-12-01

A total of 65 pore water samples were obtained from a sediment sequence in the Amami-Sankaku Basin during the IODP 351 Expedition, which consists of a 160 m thick section of terrestrial origin and underlying 1.3 km thick volcaniclastic section sampled at site U1438. Downcore variations of chemical compositions are characterized by increasing salinity/pH, increasing concentrations of Cl and Ca, and decreasing concentrations of Mg, K and Na, as well as decreasing d18O and dD. The rapid changes in those chemical components and isotopic composition occurred deeper than the lithology boundary between Unit III and Unit II, most likely as a result of substantial difference in extent of alteration above and below this boundary. The strong alterations of volcanicalstic minerals below the boundary not only result in diminishment of K, Mg, Si, and Mn, and an increase of Ca and Cl, but also depleted d18O in pore water. However, hydrogen fractionation factors between pore water and secondary minerals are less 1, and depleted dD values in pore water most likely reflect the signal of paleo-seawater. As a result, samples below the boundary are all plotted on the left side of the meteorite water line (MWL) on the dD vs. d18O plot. Above the boundary, they are placed to the right side of MWL due to substantially weakened alteration, reflecting an evolving trend in sediment setting from the predominance of alterated volcaniclasts to terrestrial pelagic sediments.

Multi-contrast MRI registration of carotid arteries based on cross-sectional images and lumen boundaries

NASA Astrophysics Data System (ADS)

Wu, Yu-Xia; Zhang, Xi; Xu, Xiao-Pan; Liu, Yang; Zhang, Guo-Peng; Li, Bao-Juan; Chen, Hui-Jun; Lu, Hong-Bing

2017-02-01

Ischemic stroke has great correlation with carotid atherosclerosis and is mostly caused by vulnerable plaques. It's particularly important to analysis the components of plaques for the detection of vulnerable plaques. Recently plaque analysis based on multi-contrast magnetic resonance imaging has attracted great attention. Though multi-contrast MR imaging has potentials in enhanced demonstration of carotid wall, its performance is hampered by the misalignment of different imaging sequences. In this study, a coarse-to-fine registration strategy based on cross-sectional images and wall boundaries is proposed to solve the problem. It includes two steps: a rigid step using the iterative closest points to register the centerlines of carotid artery extracted from multi-contrast MR images, and a non-rigid step using the thin plate spline to register the lumen boundaries of carotid artery. In the rigid step, the centerline was extracted by tracking the crosssectional images along the vessel direction calculated by Hessian matrix. In the non-rigid step, a shape context descriptor is introduced to find corresponding points of two similar boundaries. In addition, the deterministic annealing technique is used to find a globally optimized solution. The proposed strategy was evaluated by newly developed three-dimensional, fast and high resolution multi-contrast black blood MR imaging. Quantitative validation indicated that after registration, the overlap of two boundaries from different sequences is 95%, and their mean surface distance is 0.12 mm. In conclusion, the proposed algorithm has improved the accuracy of registration effectively for further component analysis of carotid plaques.

Pushing Boundaries: Introduction to the Global Service-Learning Special Section

ERIC Educational Resources Information Center

Hartman, Eric; Kiely, Richard

2014-01-01

In this introduction to the "Michigan Journal of Community Service Learning's" Special Section: "Global Service-Learning" (GSL), Hartman and Kiely describe how they each came to the field of GSL, some of its emphases and values that drew them to and sustain their commitment with this work, discuss some highlights of what GSL…

Greatly reduced phylogenetic structure in the cultivated potato clade of potatoes, Solanum section Petota

USDA-ARS?s Scientific Manuscript database

The species boundaries of wild and cultivated potatoes, Solanum section Petota, are controversial with most of the taxonomic problems in a clade containing cultivated potatoes. We here provide the first in-depth phylogenetic study of the cultivated potato clade to explore possible causes of these pr...

27 CFR 9.169 - Red Hills Lake County.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-foot contour line with the section 17 east boundary line, and continue for about 0.45 miles along the...-foot elevation line (Kelseyville Quadrangle); then (18) Proceed about 1.35 miles straight easterly to... 4, T12N, R7W, proceed approximately 0.1 miles due south along the common section line to its...

22 CFR 1101.6 - Requests for access to records.

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2010-04-01

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22 CFR 1101.17 - Annual report to Congress.

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2010-04-01

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2010-04-01

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22 CFR 1104.13 - Determination of archaeological or commercial value and cost of restoration and repair.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Determination of archaeological or commercial value and cost of restoration and repair. 1104.13 Section 1104.13 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL...

22 CFR 1101.8 - Disclosure of records to third-parties.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Disclosure of records to third-parties. 1101.8 Section 1101.8 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.8 Disclosure of records to third-parties. (a) The...

22 CFR 1104.18 - Report to the Secretary of the Interior.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 2 2014-04-01 2014-04-01 false Report to the Secretary of the Interior. 1104.18 Section 1104.18 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PROTECTION OF ARCHAEOLOGICAL RESOURCES § 1104.18 Report to the Secretary of...

22 CFR 1101.6 - Requests for access to records.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Requests for access to records. 1101.6 Section 1101.6 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.6 Requests for access to records. (a) Any individual may submit...

22 CFR 1101.11 - Fees.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Fees. 1101.11 Section 1101.11 Foreign Relations INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, UNITED STATES SECTION PRIVACY ACT OF 1974 § 1101.11 Fees. (a) Under the Act, fees can only be charged for the cost of copying records. No fees may...

27 CFR 9.39 - Paicines.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... The beginning point is the northwestern-most point of the proposed area at Township 14 South, Range 6... beginning point the boundary runs east along the north border of Sections 3, 2, and 1, Township 14 South, Range 6 East; (2) Thence south along the east border of Section 1, Township 14 South, Range 6 East...

27 CFR 9.39 - Paicines.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... The beginning point is the northwestern-most point of the proposed area at Township 14 South, Range 6... beginning point the boundary runs east along the north border of Sections 3, 2, and 1, Township 14 South, Range 6 East; (2) Thence south along the east border of Section 1, Township 14 South, Range 6 East...

Commentary on Special Section: Deficit or Difference? Interpreting Diverse Developmental Paths

ERIC Educational Resources Information Center

Callanan, Maureen; Waxman, Sandra

2013-01-01

In this special section, 6 articles address the provocative question of how to determine the boundary between difference and deficiency, for children who differ from the mainstream in some way--language, hearing, cultural background, socioeconomic status, or social understanding. Our commentary considers these articles in light of current models…

27 CFR 9.170 - Long Island.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) Boundaries. The Long Island viticultural area includes approximately 1,170 square miles or 749,146 acres and... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Long Island. 9.170 Section... Island. (a) Name. The name of the viticultural area described in this section is “Long Island.” (b...

27 CFR 9.170 - Long Island.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Boundaries. The Long Island viticultural area includes approximately 1,170 square miles or 749,146 acres and... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Long Island. 9.170 Section... Island. (a) Name. The name of the viticultural area described in this section is “Long Island.” (b...

27 CFR 9.170 - Long Island.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) Boundaries. The Long Island viticultural area includes approximately 1,170 square miles or 749,146 acres and... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Long Island. 9.170 Section... Island. (a) Name. The name of the viticultural area described in this section is “Long Island.” (b...

27 CFR 9.170 - Long Island.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) Boundaries. The Long Island viticultural area includes approximately 1,170 square miles or 749,146 acres and... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Long Island. 9.170 Section... Island. (a) Name. The name of the viticultural area described in this section is “Long Island.” (b...

27 CFR 9.170 - Long Island.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Boundaries. The Long Island viticultural area includes approximately 1,170 square miles or 749,146 acres and... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Long Island. 9.170 Section... Island. (a) Name. The name of the viticultural area described in this section is “Long Island.” (b...

77 FR 3497 - Notice of Availability of a Draft Environmental Assessment and Finding of No Significant Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-24

... Boundary and Water Commission (USIBWC) and Bureau of Land Management (BLM) Lands in Seldon Canyon, Do... through 1508); and the United States Section, Operational Procedures for Implementing Section 102 of NEPA... Water Commission and Bureau of Land Management Lands are available. An environmental impact statement...

Wall interference and boundary simulation in a transonic wind tunnel with a discretely slotted test section

NASA Technical Reports Server (NTRS)

Al-Saadi, Jassim A.

1993-01-01

A computational simulation of a transonic wind tunnel test section with longitudinally slotted walls is developed and described herein. The nonlinear slot model includes dynamic pressure effects and a plenum pressure constraint, and each slot is treated individually. The solution is performed using a finite-difference method that solves an extended transonic small disturbance equation. The walls serve as the outer boundary conditions in the relaxation technique, and an interaction procedure is used at the slotted walls. Measured boundary pressures are not required to establish the wall conditions but are currently used to assess the accuracy of the simulation. This method can also calculate a free-air solution as well as solutions that employ the classical homogeneous wall conditions. The simulation is used to examine two commercial transport aircraft models at a supercritical Mach number for zero-lift and cruise conditions. Good agreement between measured and calculated wall pressures is obtained for the model geometries and flow conditions examined herein. Some localized disagreement is noted, which is attributed to improper simulation of viscous effects in the slots.

Final results on the Jurassic-Cretaceous boundary in the Gresten Klippenbelt (Austria): Macro-, micro-, nannofossils, isotopes, geochemistry, susceptibility, gamma-log and palaeomagnetic data as environmental proxies of the early Penninic Ocean history

NASA Astrophysics Data System (ADS)

Lukeneder, A.; Halásová, E.; Kroh, A.; Mayrhofer, S.; Pruner, P.; Reháková, D.; Schnabl, P.; Sprovieri, M.

2009-04-01

Jurassic to Lower Cretaceous pelagic sediments are well known to form a major element of the northernmost tectonic units of the Gresten Klippenbelt (Lower Austria). The Penninic Ocean was a side tract of the Central Atlantic Oceanic System intercalated between the European and the Austroalpine plates. Its opening started during the Mid Jurrasic, as rifting of the of the oceanic crust between the European and the Austroalpine plates. The turnover of the deposition on the European shelf (Helvetic Zone) from deep-water siliciclastics into pelagic carbonates is correlated with the deepening of this newly arising ocean. Within the Gresten Klippenbelt Unit, this transition is reflected by the lithostratigraphic boundary between the Tithonian marl-limestone succession and the Berriasian limestones of the Blassenstein Formation. This boundary is well exposed in a newly discovered site at Nutzhof, in the heart of Lower Austria (Kroh and Lukeneder 2009, Lukeneder 2009, Pruner, Schnabl, and Lukeneder 2009, Reháková, Halásová and Lukeneder 2009). Biostratigraphy. According to microfossil (calcareous dinoflagellates, calpionellids) and palaeomagnetic data, the association indicates that the cephalopod-bearing beds of the Nutzhof section belong to the Carpistomiosphaera tithonica-Zone of the Early Tithonian up to the Calpionella Zone of the Middle Berriasian. This interval corresponds to the ammonoid zones from the Early Tithonian Hybonoticeras hybonotum-Zone up to the Middle Berriasian Subthurmannia occitanica-Zone. Ammonoids. Late Jurassic to Early Cretaceous ammonoids were collected at the Nutzhof locality in the eastern part of the Gresten Klippenbelt in Lower Austria. The cephalopod fauna from the Blassenstein Formation, correlated with micro- and nannofossil data from the marly unit and the limestone unit, indicates Early Tithonian to Middle Berriasian age (Hybonoticeras hybonotum Zone up to the Subthurmannia occitanica Zone). According to the correlation of the fossil and magnetostratigraphic data, the entire succession of the Nutzhof section embraces a duration of approx. 8 million years (approx. 150-142 Ma). The deposition of the limestones, marly limestones and marls in this interval occurred during depositionally (e.g. tectonics) unstable conditions.The ammonite fauna comprises 6 different genera, each apparently represented by a single species. The occurrence at the Nutzhof section is dominated by ammonites of the perisphinctid-type. Ammonitina are the most frequent component (60 per cent; Subplanites and Haploceras), followed by the Phylloceratina (25per cent; Ptychophylloceras and Phylloceras), and the Lytoceratina (15 per cent; represented by Lytoceras and Leptotetragonites). The ammonite fauna consists solely of Mediterranean elements. Crinoids. Only the Tithonian part of the section proved suitable for bulk sampling. Four crinoid taxa (Margocrinus cf. pentagonalis, Saccocoma tenella, Crassicoma ? sp., and Phyllocrinus belbekensis could be documented. Among these only S. tenella and probably Crassicoma ? sp. appear to be autochthonous, the others are interpreted as transported based on preservation and size range. Observed changes in lithology and microfauna may be reflect geodynamically induced palaeogeographic changes and/or basinal deepening. Microfossils. The biostratigraphic study based on the distribution of calpionellids allowed us to distinguish the Boneti Subzone of the Chitinoidella Zone in the Nutzhof section. The J/K boundary in this section is situated between the Crassicollaria and Calpionella Zone (interval limited by samples 7.0-5.6). This base is defined by the morphological change of Calpionella alpina tests. The base of the Crassicollaria Zone approximately coincides with the onset of Tintinnopsella remanei and the base of the standard Calpionella Zone, with the monospecific calpionellid association being dominated by Calpionella alpina. Two further Subzones (Ferasini and Elliptica) of the standard Calpionella Zone were recognized in radiolarian-calpionellid and calpionellid-radiolarian wackestones in the overlying topmost part of the investigated sequence. Nannofossils. Calcareous nannofossils from the Nutzhof section belong to low poorly diversified, because of the lithology. Nonetheless, the appearance of several important genera was determined, allowing the studied deposits to be attributed to the Early, Middle and Late Tithonian, the approximation of the Tithonian-Berriasian boundary, and the definition of the Early Berriasian nannofossil zones. The results show the major role of the coccoliths of the family Watznaueriaceae and nannoliths of the genera Conusphaera, Nannoconus and Polycostella in the assemblage composition. The interval between the FAD of Nannoconus wintereri co-occurring with small nannoconids in sample No 9 (the uppermost Tithonian) and the FAD of Nannoconus kamptneri minor in sample No 5 (lowermost Berriasian; 143.92 Ma after Hardenbol et al. 1998) is interpreted as the Tithonian-Berriasian boundary interval. The nannoconid dominance ("Nannoconus world") starts, also in Nutzhof profile, in the lowermost Berriasian. Palaeomagnetic data. The principal aim of detailed magnetostratigraphic and micropalaeontological investigation on the Jurassic/Cretaceous (J/K) boundary is precisely determine the boundaries of magnetozones and narrow reverse subzones, and find global correlation across the J/K boundary. A high resolution study focusing on the detailed biostratigraphy of the limestone-, marly limestone- and marl succession at Nutzhof has been carried out. Eleven magnetic polarity zones, six reverse (R) and five normal (N) polarity - are included in the whole interval (18 m) around J/K boundary of Nutzhof section. The J/K boundary (the Berriasian Stage base), located near Calpionella Zone base roughly corresponds to magnetozone M19N a succession of M-zones correlative with M17N to M22R. Low-field magnetic susceptibility (k) ranges from -5.9 to 94.9×10-6 SI and the intensity of the natural remanent magnetization (NRM) varies between 31 and 615×10-6 A/m. The samples display a two- to three-component remanence. The average sampling density for the whole section was around two samples per 1 m of true thickness of limestone strata in these preliminary results. The next step of investigation will be to precisely determine the boundaries of magnetozones M19 and M20 including narrow reverse subzones with the high resolution sampling density for the whole section. Stable isotope data (C, O, Sr). High-resolution reconstruction of the carbon cycle, by isotope stratigraphy, is the key for drawing conclusions on the palaeooceanography of the Nutzhof area. The approach using oxygen isotope analysis, by constraining diagenesis impacts, will yield a picture of the Lower Cretaceous palaeoclimatology here. The investigations on istopes will be rigorously linked and networked with measurements and results of cyclostratigraphy and lithostratigraphy. C-istopes are extremely important calibration tools between ammonoids and magnetostratigraphy (Henning et al. 1999). Cyclostratigraphy is crucial in comparing the lithologic appearance of different units and the carbon isotope records. A detailed cyclostratigraphic reconstruction of the record will be carried out by comparing (1) the results obtained by time series analysis of the collected faunal and isotope proxy records with (2) the reconstructed lithologic cycle patterns of the studied sedimentary sections. A first-order floating cyclostratigraphy will be refined using a tentative calibration of the record to the available numerical solutions of the insolation curve. This approach should provide an absolute age for the different stratigraphic events recognised throughout the record. Gamma-log and Geochemistry. We conducted geochemical analyses of the carbonate, sulphur and organic carbon content in the limestones and marls of the different lithological units. The gamma log measures the radioactivity of the rock and represents a direct function of its clay-mineral content. Higher radioactivity reflects a higher clay content. The gamma-log curve supports the biostratigraphic data very well. The gamma response becomes gradually weaker in the upper, undisturbed part of the section (Nu10-Nu0, Berriasian). The lower part (Nu18-Nu10, Tithonian) of the section shows the highest gamma responses. The gamma curve pattern at Nutzhof therefore shows decreasing values what corresponds well with decreasing values of susceptibility as well with the contrastingly, increasing values in carbonate content (from 50 per cent up to 95 per cent CaCo3) and increasing grey scale values (up to 250). The above reported results strongly suggest that the section mirrors a change of the depositional position of the Nutzhof section from a shallower into a deeper region, and a more stable environment on the European Helvetic shelf to slope during the Late Jurassic to Early Cretaceous time. References Hardenbol, J., Thierry, J., Farley, M. B., Jacquin, T., de Graciansky, P. C. & Vail, P. R. (1998): Mesozoic and Cenozoic sequence stratigraphy of European basins. - SEMP, Special Publications, 60, 1998. Tulsa. Henning, S., Weissert, H., Bulot, L. 1999. C-isotope stratigraphy, a calibration tool between ammonite- and magnethostratigraphy: the Valanginian-Hauterivian transition. Geologica Carpathica, 50 (1), 91-96. Kroh, A., Lukeneder, A. 2009. Crinoids from the Late Jurassic of the Nutzhof section (Lower Austria, Gresten Klippenbelt). - Annalen des Naturhistorischen Museums in Wien, Serie A, 110: 383-399. Lukeneder A. 2009. New biostratigraphic ammonite data from the Jurassic/Cretaceous boundary at Nutzhof (Gresten Klippenbelt, Lower Austria) Annalen des Naturhistorischen Museums in Wien, Serie A, 110: 313-329. Pruner, P. Schnabl, P., Lukeneder A. 2009. Preliminary results of magnetostratigraphic investigations across the Jurassic/Cretaceous boundary strata at Nutzhof, Austria. Annalen des Naturhistorischen Museums in Wien, Serie A, 110: 331-344. Reháková, D., Halásová, E., Lukeneder, A. 2009. The Jurassic-Cretaceous boundary in the Gresten Klippen Belt (Nutzhof, Lower Austria): Implications for Micro- and Nannofacies analysis. Annalen des Naturhistorischen Museums in Wien, Serie A, 110: 345-381.

Hypersonic Wind-Tunnel Measurements of Boundary-Layer Pressure Fluctuations

DTIC Science & Technology

2009-08-01

experiments. The third and fourth sections of the cone are designed to hold the instrumentation. The model can be run as a 0.102-m base-diameter cone...using the third section only, or 28 Figure 3.10. Glow-perturber section the fourth section can be added to increase the cone base diameter to 0.127 m...the second sensor. The third sensor shows an increase in frequency components above 15 kHz as well as a rise in lower frequencies. As transition

Cyclostratigraphic calibration of the Famennian stage (Late Devonian, Illinois Basin, USA)

NASA Astrophysics Data System (ADS)

Pas, Damien; Hinnov, Linda; Day, James E. (Jed); Kodama, Kenneth; Sinnesael, Matthias; Liu, Wei

2018-04-01

The Late Devonian biosphere was affected by two of the most severe biodiversity crises in Earth's history, the Kellwasser and Hangenberg events near the Frasnian-Famennian (F-F) and the Devonian-Carboniferous (D-C) boundaries, respectively. Current hypotheses for the causes of the Late Devonian extinctions are focused on climate changes and associated ocean anoxia. Testing these hypotheses has been impeded by a lack of sufficient temporal resolution in paleobiological, tectonic and climate proxy records. While there have been recent advances in astronomical calibration that have improved the accuracy of the Frasnian time scale and part of the Famennian, the time duration of the entire Famennian Stage remains poorly constrained. During the Late Devonian, a complete Late Frasnian-Early Carboniferous succession of deep-shelf deposits accumulated in the epieric sea in Illinois Basin of the central North-American mid-continent. A record of this sequence is captured in three overlapping cores (H-30, Sullivan and H-32). The H-30 core section spans the F-F boundary; the Sullivan section spans almost all of the Famennian and the H-32 section sampled spans the interval of the Upper Famennian and the D-C boundary. To have the best chance of capturing Milankovitch cycles, 2000 rock samples were collected at minimum 5-cm-interval across the entire sequence. Magnetic susceptibility (MS) was measured on each sample and the preservation of climatic information into the MS signal was verified through geochemical analyses and low-temperature magnetic susceptibility acquisition. To estimate the duration of the Famennian Stage, we applied multiple spectral techniques and tuned the MS signal using the highly stable 405 kyr cycle for Sullivan and the obliquity cycle for the H-30 and H-32 cores. Based on the correlation between the cores we constructed a Famennian floating astronomical time scale, which indicates a duration of 13.5 ± 0.5 myr. An uncertainty of 0.5 myr was estimated for the uncertainties arising from the errors in the stratigraphic position of the F-F and D-C boundaries, and the 405 kyr cycle counting. Interpolated from the high-resolution U-Pb radiometric ages available for the Devonian-Carboniferous boundary we recalibrated the Frasnian-Famennian boundary numerical age to 372.4 ± 0.9 Ma.

Studies of the phase gradient at the boundary of the phase diffusion equation, motivated by peculiar wave patterns of rhythmic contraction in the amoeboid movement of Physarum polycephalum

NASA Astrophysics Data System (ADS)

Iima, Makoto; Kori, Hiroshi; Nakagaki, Toshiyuki

2017-04-01

The boundary of a cell is the interface with its surroundings and plays a key role in controlling the cell movement adaptations to different environments. We propose a study of the boundary effects on the patterns and waves of the rhythmic contractions in plasmodia of Physarum polycephalum, a tractable model organism of the amoeboid type. Boundary effects are defined as the effects of both the boundary conditions and the boundary shape. The rhythmicity of contraction can be modulated by local stimulation of temperature, light and chemicals, and by local deformation of cell shape via mechanosensitive ion channels as well. First, we examined the effects of boundary cell shapes in the case of a special shape resembling a tadpole, while requiring that the natural frequency in the proximity of the boundary is slightly higher and uniform. The simulation model reproduced the approximate propagated wave, from the tail to the head, while the inward waves were observed only near the periphery of the head section of the tadpole-shape. A key finding was that the frequency of the rhythmic contractions depended on the local shape of cell boundary. This implies that the boundary conditions of the phase were not always homogeneous. To understand the dependency, we reduced the two-dimensional model into a one-dimensional continuum model with Neumann boundary conditions. Here, the boundary conditions reflect the frequency distribution at the boundary. We described the analytic solutions and calculated the relationship between the boundary conditions and the wave propagation for a one-dimensional model of the continuous oscillatory field and a discrete coupled oscillator system. The results obtained may not be limited to cell movement of Physarum, but may be applicable to the other physical systems since the analysis used a generic phase diffusion equation.

User-guided automated segmentation of time-series ultrasound images for measuring vasoreactivity of the brachial artery induced by flow mediation

NASA Astrophysics Data System (ADS)

Sehgal, Chandra M.; Kao, Yen H.; Cary, Ted W.; Arger, Peter H.; Mohler, Emile R.

2005-04-01

Endothelial dysfunction in response to vasoactive stimuli is closely associated with diseases such as atherosclerosis, hypertension and congestive heart failure. The current method of using ultrasound to image the brachial artery along the longitudinal axis is insensitive for measuring the small vasodilatation that occurs in response to flow mediation. The goal of this study is to overcome this limitation by using cross-sectional imaging of the brachial artery in conjunction with the User-Guided Automated Boundary Detection (UGABD) algorithm for extracting arterial boundaries. High-resolution ultrasound imaging was performed on rigid plastic tubing, on elastic rubber tubing phantoms with steady and pulsatile flow, and on the brachial artery of a healthy volunteer undergoing reactive hyperemia. The area of cross section of time-series images was analyzed by UGABD by propagating the boundary from one frame to the next. The UGABD results were compared by linear correlation with those obtained by manual tracing. UGABD measured the cross-sectional area of the phantom tubing to within 5% of the true area. The algorithm correctly detected pulsatile vasomotion in phantoms and in the brachial artery. A comparison of area measurements made using UGABD with those made by manual tracings yielded a correlation of 0.9 and 0.8 for phantoms and arteries, respectively. The peak vasodilatation due to reactive hyperemia was two orders of magnitude greater in pixel count than that measured by longitudinal imaging. Cross-sectional imaging is more sensitive than longitudinal imaging for measuring flow-mediated dilatation of brachial artery, and thus may be more suitable for evaluating endothelial dysfunction.

Ureilite Thin Section Preparation

NASA Technical Reports Server (NTRS)

Harrington, R.; Righter, K.

2014-01-01

Preparing thin and thick sections of ureilite type meteorites is a challenge that can confound even the most experienced section preparer. A common characteristic of these samples is the presence of carbon phases, particularly nanodiamonds, in the matrix along silicate grain boundaries, fractures, and cleavage plains [1]. The extreme hardness of the nanodiamonds presents a challenge to the section preparer in the form of high surface relief on the section. This hard material also causes considerable wear and tear on equipment and materials that are used for making the sections. These issues will be discussed and potentially helpful measures will be presented.

Numerical investigations of shock wave interaction with laminar boundary layer on compressor profile

NASA Astrophysics Data System (ADS)

Piotrowicz, M.; Flaszyński, P.

2016-10-01

The investigation of shockwave boundary layer interaction on suction side of transonic compressor blade is one of main objectives of TFAST project (Transition Location Effect on Shock Wave Boundary Layer Interaction). In order to look more closely into the flow structure on suction side of a profile, a design of generic test section in linear transonic wind tunnel was proposed. The experimental and numerical results of flow structure on a suction side of the compressor profile investigations are presented. The numerical simulations are carried out for EARSM (Explicit Algebraic Reynolds Stress Model) turbulence model with transition model. The result are compared with oil flow visualisation, schlieren pictures, Pressure Sensitive Paint (PSP) and static pressure.

Cenozoic Polarity Time Scale (CPTS) as the Tool of Dating and Correlation of the Cenozoic Strata in North-Eastern Russia

NASA Astrophysics Data System (ADS)

Minyuk, P.

2004-12-01

About 70 sections of continental and marine sediments covering he age through Paleocene to Pleistocene have been studied in North-Eastern Russia. Zones of polarity were used to determine the age and regional correlation of the strata with different biostratigraphic characteristic. On the basis of relation of magnetic zones to the CPTS, the dating of the major paleoclimatic and stratigraphic boundaries of the region fixed in the local stratons, has been obtained. There are the following events: chrones 25-24r - warming of the climate (boundary layers between Paleocene and Eocene ); chrones 13r - the beginning of the Eocene-Oligocene climatic pessimum; the boundary of the chrones 6Cn-6Cr - the climatic pessimum at the boundary of the Paleogene and Neogene; chrones 5Br - the middle of the chrone 5Adn - the first climatic optimum of the Miocene (the boundary of the Lower and Middle Miocene); chrones 5r - the lower part of the chrone 5n - the second climatic optimum of the Miocene ( the boundary interval between Middle and Lower Miocene). According to the paleomagnetic data, the supposed boundaries of the Miocene and Pliocene, Pliocene and Pleistocene are considered to be problematic and are fixed in the unique

Application of the Program Profile for the Design of Low-Speed, Low- Observable Configuration Airfoils

DTIC Science & Technology

1992-12-01

112 61 . Airfoil T503 - t/c = 3.79% .... ........... .. 113 62. Airfoil T503 Leading-Edge - t/c = 3.79% ..... ... 114 63. Pressure...points on C unit circle, 6 slope of airfoil surface near trailing edge 61 boundary-layer displacement thickness 62 boundary-layer momentum thickness 63...equivalent thickness NACA 4-digit airfoils . 4 II. Theory Potential-Flow Design Method This section will overview the basic theory used in PROFILE. Eppler

Computational Fluid Dynamics (CFD) Simulations of a Finned Projectile with Microflaps for Flow Control

DTIC Science & Technology

2016-04-01

fields associated with these control mechanisms for US Army weapons are complex, involving 3-dimensional (3-D) shock- boundary layer interactions...distribution over the rear finned section and thus produce control forces and moments. Dykes et al.6 used a flat - plate fin interaction design of...cells—tetrahedrals, triangular prisms, and pyramids—were used in the mesh. Grid points shown in Fig. 3a were clustered in the boundary layer region

Direct imaging of Cl- and Cu-induced short-circuit efficiency changes in CdTe solar cells

DOE PAGES

Poplawsky, Jonathan D.; Parish, Chad M.; Leonard, Donovan N.; ...

2014-05-30

To achieve high-efficiency polycrystalline CdTe-based thin-film solar cells, the CdTe absorbers must go through a post-deposition CdCl 2 heat treatment followed by a Cu diffusion step. To better understand the roles of each treatment with regard to improving grains, grain boundaries, and interfaces, CdTe solar cells with and without Cu diffusion and CdCl 2 heat treatments are investigated using cross-sectional electron beam induced current, electron backscatter diffraction, and scanning transmission electron microscope techniques. The evolution of the cross-sectional carrier collection profile due to these treatments that cause an increase in short-circuit current and higher open-circuit voltage are identified. Additionally, anmore » increased carrier collection in grain boundaries after either/both of these treatments is revealed. The increased current at the grain boundaries is shown to be due to the presence of a space charge region with an intrinsic carrier collection profile width of ≈350 nm. Scanning transmission electron microscope electron-energy loss spectroscopy shows a decreased Te and increased Cl concentration in grain boundaries after treatment, which causes the inversion. Furthermore, each treatment improves the overall carrier collection efficiency of the cell separately, and, therefore, the benefits realized by each treatment are shown to be independent of each other.« less

Further investigation of a finite difference procedure for analyzing the transonic flow about harmonically oscillating airfoils and wings

NASA Technical Reports Server (NTRS)

Weatherill, W. H.; Ehlers, F. E.; Yip, E.; Sebastian, J. D.

1980-01-01

Analytical and empirical studies of a finite difference method for the solution of the transonic flow about harmonically oscillating wings and airfoils are presented. The procedure is based on separating the velocity potential into steady and unsteady parts and linearizing the resulting unsteady equations for small disturbances. The steady velocity potential is obtained first from the well-known nonlinear equation for steady transonic flow. The unsteady velocity potential is then obtained from a linear differential equation in complex form with spatially varying coefficients. Since sinusoidal motion is assumed, the unsteady equation is independent of time. An out-of-core direct solution procedure was developed and applied to two-dimensional sections. Results are presented for a section of vanishing thickness in subsonic flow and an NACA 64A006 airfoil in supersonic flow. Good correlation is obtained in the first case at values of Mach number and reduced frequency of direct interest in flutter analyses. Reasonable results are obtained in the second case. Comparisons of two-dimensional finite difference solutions with exact analytic solutions indicate that the accuracy of the difference solution is dependent on the boundary conditions used on the outer boundaries. Homogeneous boundary conditions on the mesh edges that yield complex eigenvalues give the most accurate finite difference solutions. The plane outgoing wave boundary conditions meet these requirements.

Representation of Nucleation Mode Microphysics in a Global Aerosol Model with Sectional Microphysics

NASA Technical Reports Server (NTRS)

Lee, Y. H.; Pierce, J. R.; Adams, P. J.

2013-01-01

In models, nucleation mode (1 nm

Flight-measured laminar boundary-layer transition phenomena including stability theory analysis

NASA Technical Reports Server (NTRS)

Obara, C. J.; Holmes, B. J.

1985-01-01

Flight experiments were conducted on a single-engine turboprop aircraft fitted with a 92-in-chord, 3-ft-span natural laminar flow glove at glove section lift coefficients from 0.15 to 1.10. The boundary-layer transition measurement methods used included sublimating chemicals and surface hot-film sensors. Transition occurred downstream of the minimum pressure point. Hot-film sensors provided a well-defined indication of laminar, laminar-separation, transitional, and turbulent boundary layers. Theoretical calculations of the boundary-layer parameters provided close agreement between the predicted laminar-separation point and the measured transition location. Tollmien-Schlichting (T-S) wave growth n-factors between 15 and 17 were calculated at the predicted point of laminar separation. These results suggest that for many practical airplane cruise conditions, laminar separation (as opposed to T-S instability) is the major cause of transition in predominantly two-dimensional flows.

Airfoil self-noise and prediction

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.; Pope, D. Stuart; Marcolini, Michael A.

1989-01-01

A prediction method is developed for the self-generated noise of an airfoil blade encountering smooth flow. The prediction methods for the individual self-noise mechanisms are semiempirical and are based on previous theoretical studies and data obtained from tests of two- and three-dimensional airfoil blade sections. The self-noise mechanisms are due to specific boundary-layer phenomena, that is, the boundary-layer turbulence passing the trailing edge, separated-boundary-layer and stalled flow over an airfoil, vortex shedding due to laminar boundary layer instabilities, vortex shedding from blunt trailing edges, and the turbulent vortex flow existing near the tip of lifting blades. The predictions are compared successfully with published data from three self-noise studies of different airfoil shapes. An application of the prediction method is reported for a large scale-model helicopter rotor, and the predictions compared well with experimental broadband noise measurements. A computer code of the method is given.

Detritus in K/T boundary clays of western North America - Evidence against a single oceanic impact

NASA Technical Reports Server (NTRS)

Sharpton, V. L.; Schuraytz, B. C.; Burke, K.; Murali, A. V.; Ryder, G.

1990-01-01

Understanding the crustal signature of impact ejecta contained in the Cretaceous/Tertiary (K/T) boundary layer is crucial to constraining the possible site(s) of the postulated K/T impact event. The relatively unaltered clastic constituents of the boundary layer at widely separated outcrops within the western interior of North America are not compatible with a single oceanic impact but require instead an impact site on a continent or continental margin. On the other hand, chemical compositions of highly altered K/T boundary layer components in some marine sections have suggested to others an impact into oceanic crust. We suspect that post-depositional alteration within the marine setting accounts for this apparent oceanic affinity. If, however, this is not the case, multiple simultaneous impacts, striking continent as well as ocean floor, would seem to be required.

Determination of Boundary-Layer Transition on Three Symmetrical Airfoils in the NACA Full-Scale Wind Tunnel

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Becker, John V

1938-01-01

For the purpose of studying the transition from laminar to turbulent flow, boundary-layer measurements were made in the NACA full-scale wind tunnel on three symmetrical airfoils of NACA 0009, 0012, and 0018 sections. The effects of variations in lift coefficient, Reynolds number, and airfoil thickness on transition were investigated. Air speed in the boundary layer was measured by total-head tubes and by hot wires; a comparison of transition as indicated by the two techniques was obtained. The results indicate no unique value of Reynolds number for the transition, whether the Reynolds number is based upon the distance along the chord or upon the thickness of the boundary layer at the transition point. In general, the transition is not abrupt and occurs in a region that varies in length as a function of the test conditions.

Repulsive Casimir effect from extra dimensions and Robin boundary conditions: From branes to pistons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizalde, E.; Odintsov, S. D.; Institucio Catalana de Recerca i Estudis Avanccats

2009-03-15

We evaluate the Casimir energy and force for a massive scalar field with general curvature coupling parameter, subject to Robin boundary conditions on two codimension-one parallel plates, located on a (D+1)-dimensional background spacetime with an arbitrary internal space. The most general case of different Robin coefficients on the two separate plates is considered. With independence of the geometry of the internal space, the Casimir forces are seen to be attractive for special cases of Dirichlet or Neumann boundary conditions on both plates and repulsive for Dirichlet boundary conditions on one plate and Neumann boundary conditions on the other. For Robinmore » boundary conditions, the Casimir forces can be either attractive or repulsive, depending on the Robin coefficients and the separation between the plates, what is actually remarkable and useful. Indeed, we demonstrate the existence of an equilibrium point for the interplate distance, which is stabilized due to the Casimir force, and show that stability is enhanced by the presence of the extra dimensions. Applications of these properties in braneworld models are discussed. Finally, the corresponding results are generalized to the geometry of a piston of arbitrary cross section.« less

A spectrally accurate boundary-layer code for infinite swept wings

NASA Technical Reports Server (NTRS)

Pruett, C. David

1994-01-01

This report documents the development, validation, and application of a spectrally accurate boundary-layer code, WINGBL2, which has been designed specifically for use in stability analyses of swept-wing configurations. Currently, we consider only the quasi-three-dimensional case of an infinitely long wing of constant cross section. The effects of streamwise curvature, streamwise pressure gradient, and wall suction and/or blowing are taken into account in the governing equations and boundary conditions. The boundary-layer equations are formulated both for the attachment-line flow and for the evolving boundary layer. The boundary-layer equations are solved by marching in the direction perpendicular to the leading edge, for which high-order (up to fifth) backward differencing techniques are used. In the wall-normal direction, a spectral collocation method, based upon Chebyshev polynomial approximations, is exploited. The accuracy, efficiency, and user-friendliness of WINGBL2 make it well suited for applications to linear stability theory, parabolized stability equation methodology, direct numerical simulation, and large-eddy simulation. The method is validated against existing schemes for three test cases, including incompressible swept Hiemenz flow and Mach 2.4 flow over an airfoil swept at 70 deg to the free stream.

Domain pinning near a single-grain boundary in tetragonal and rhombohedral lead zirconate titanate films

DOE PAGES

Marincel, Dan M.; Zhang, H. R.; Briston, J.; ...

2015-04-27

The interaction of grain boundaries with ferroelectric domain walls strongly influences the extrinsic contribution to piezoelectric activity in Pb(Zr,Ti)O 3 (PZT), ubiquitous in modern transducers and actuators. However, the fundamental understanding of these phenomena has been limited by complex mechanisms originating from the interplay of atomic-level domain wall pinning, collective domain wall dynamics, and emergent mesoscopic behavior. This contribution utilizes engineered grain boundaries created by depositing epitaxial PZT films with various Zr:Ti ratio onto 24º SrTiO 3 tilt bicrystals. The nonlinear piezoelectric response and surface domain structure across the boundary are investigated using piezoresponse force microscopy whilst cross section domainmore » structure is studied using transmission electron microscopy. The grain boundary reduces domain wall motion over a width of 800±70 nm for PZT 45:55 and 450±30 nm for PZT 52:48. Phase field modeling provides an understanding of the elastic and electric fields associated with the grain boundary and local domain configurations. In conclusion, this study demonstrates that complex mesoscopic behaviors can be explored to complement atomic-level pictures of the material system.« less

Dynamic Stall on Advanced Airfoil Sections,

DTIC Science & Technology

1980-05-01

that travel downstream from the regime, where the boundary-layer charac- leading-edge region; throughout the teristics differ the most. Before compar...largest chord lengths of travel . As we shall see value of CL, , but it also has very large in later sections, the onset of super- negative pitc-iing...or chordlengths of travel , and the or deep dynamic stall characteristics of curves are phased so that the angles of any of the helicopter sections. The

Numerical analysis of residual stresses in preforms of stress applying part for PANDA-type polarization maintaining optical fibers in view of technological imperfections of the doped zone geometry

NASA Astrophysics Data System (ADS)

Trufanov, Aleksandr N.; Trufanov, Nikolay A.; Semenov, Nikita V.

2016-09-01

The experimental data analysis of the stress applying rod section geometry for the PANDA-type polarization maintaining optical fiber has been performed. The dependencies of the change in the radial dimensions of the preform and the doping boundary on the angular coordinate have been obtained. The original algorithm of experimental data statistic analysis, which enables determination of the specimens' characteristic form of section, has been described. The influence of actual doped zone geometry on the residual stress fields formed during the stress rod preform fabrication has been investigated. It has been established that the deviation of the boundary between pure silica and the doped zone from the circular shape results in dissymmetry and local concentrations of the residual stress fields along the section, which can cause preforms destruction at high degrees of doping. The observed geometry deviations of up to 10% lead to the increase of the maximum stress intensity value by over 20%.

Real-Time Flight Envelope Monitoring System

NASA Technical Reports Server (NTRS)

Kerho, Michael; Bragg, Michael B.; Ansell, Phillip J.

2012-01-01

The objective of this effort was to show that real-time aircraft control-surface hinge-moment information could be used to provide a robust and reliable prediction of vehicle performance and control authority degradation. For a given airfoil section with a control surface -- be it a wing with an aileron, rudder, or elevator -- the control-surface hinge moment is sensitive to the aerodynamic characteristics of the section. As a result, changes in the aerodynamics of the section due to angle-of-attack or environmental effects such as icing, heavy rain, surface contaminants, bird strikes, or battle damage will affect the control surface hinge moment. These changes include both the magnitude of the hinge moment and its sign in a time-averaged sense, and the variation of the hinge moment with time. The current program attempts to take the real-time hinge moment information from the aircraft control surfaces and develop a system to predict aircraft envelope boundaries across a range of conditions, alerting the flight crew to reductions in aircraft controllability and flight boundaries.

Hydraulic, geomorphic, and trout habitat conditions of the Lake Fork of the Gunnison River in Hinsdale County, Lake City, Colorado, Water Years 2010-2011

USGS Publications Warehouse

Williams, Cory A.; Richards, Rodney J.; Schaffrath, Keelin R.

2015-01-01

Sediment mobility is an important process for flushing fine sediments from within the gravel frameworks. Evaluations of channel and flow characteristics at cross-section locations 2–8 show a range of streambed mobility. In general, boundary shear stress and streambed mobility increase with increases in streamflow. Within the cross sections, the greatest boundary shear stress occurs towards the center of the channel. Reach-scale assessment of sediment mobility in the lower reach shows increased streambed mobility. This is due in part to smaller grain sizes in the lower reach, but may also reflect the greater extent of channel alterations, specifically the temporary berms constructed by CDOT in the late 1980s and 1990s, present in this reach.

High-Fidelity PIV of a Naturally Grown High Reynolds Number Turbulent Boundary Layer

NASA Astrophysics Data System (ADS)

Biles, Drummond; White, Chris; Klewicki, Joeseph

2017-11-01

High-fidelity particle image velocimetry data acquired in the Flow Physics Facility (FPF) at the University of New Hampshire is presented. Having a test section length of 72m, the FPF employs the ``big and slow'' approach to obtain well-resolved turbulent boundary layer measurements at high Reynolds number. We report on PIV measurements acquired in the streamwise-wall-normal plane at a downstream position 59m from the test-section inlet over the friction Reynolds number range 7000 < Reτ < 15000 . Local flow tracer seeding is employed through a wall-mounted slot fed by a large volume plenum located 13.4m upstream of the PIV measurement station. Both time-independent and time-dependent turbulent flow statistics are presented and compared to existing data.