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Sample records for calvert bluff formation

  1. The origin and distribution of HAPs elements in relation to maceral composition of the A1 lignite bed (Paleocene, Calvert Bluff Formation, Wilcox Group), Calvert mine area, east-central Texas

    USGS Publications Warehouse

    Crowley, S.S.; Warwick, P.D.; Ruppert, L.F.; Pontolillo, J.

    1997-01-01

    The origin and distribution of twelve potentially Hazardous Air Pollutants (HAPs; As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb Sb, Se, and U) identified in the 1990 Clean Air Act Amendments were examined in relation to the maceral composition of the A1 bed (Paleocene, Calvert Bluff Formation, Wilcox Group) of the Calvert mine in east-central Texas. The 3.2 m-thick A1 bed was divided into nine incremental channel samples (7 lignite samples and 2 shaley coal samples) on the basis of megascopic characteristics. Results indicate that As, Cd, Cr, Ni, Pb, Sb, and U are strongly correlated with ash yield and are enriched in the shaley coal samples. We infer that these elements are associated with inorganic constituents in the coal bed and may be derived from a penecontemporaneous stream channel located several kilometers southeast of the mining block. Of the HAPs elements studied, Mn and Hg are the most poorly correlated to ash yield. We infer an organic association for Mn; Hg may be associated with pyrite. The rest of the trace elements (Be, Co, and Se) are weakly correlated with ash yield. Further analytical work is necessary to determine the mode of occurrence for these elements. Overall, concentrations of the HAPs elements are generally similar to or less than those reported in previous studies of lignites of the Wilcox Group, east-central region, Texas. Petrographic analysis indicates the following ranges in composition for the seven lignite samples: liptinites (5-8%), huminites (88-95%), and inertinites (trace amounts to 7%). Samples from the middle portion of the A1 bed contain abundant crypto-eugelinite compared to the rest of the samples; this relationship suggests that the degradation of plant material was an important process during the development of the peat mire. With the exception of Hg and Mn, relatively low levels of the HAPs elements studied are found in the samples containing abundant crypto-eugelinite. We infer that the peat-forming environment for this portion of the coal bed was very wet with minimal detrital input. Relatively high concentrations of crypto-humotelinite were found in samples from the top and base of the coal bed. The presence of abundant crypto-humotelinite in this part of the coal bed suggests the accumulation of wood-rich peat under conditions conducive to a high degree of tissue preservation in the peat mire. Although several of the trace elements (Be, Co, Ni, and Sb) exhibit enrichment in these samples, they are not necessarily chemically associated with humotelinite. We infer that these elements, with the exception of Be, are possibly associated with deposition of the roof and floor rock of the coal bed; however, further analytical work would be necessary to confirm this hypothesis. Beryllium may have an organic origin. ?? 1997 Elsevier Science B.V.

  2. Coal geology of the Paleocene-Eocene Calvert Bluff Formation (Wilcox Group) and the Eocene Manning Formation (Jackson Group) in east-central Texas; field trip guidebook for the Society for Organic Petrology, Twelfth Annual Meeting, The Woodlands, Texas, August 30, 1995

    USGS Publications Warehouse

    Warwick, Peter D.; Crowley, Sharon S.

    1995-01-01

    The Jackson and Wilcox Groups of eastern Texas (fig. 1) are the major lignite producing intervals in the Gulf Region. Within these groups, the major lignite-producing formations are the Paleocene-Eocene Calvert Bluff Formation (Wilcox) and the Eocene Manning Formation (Jackson). According to the Keystone Coal Industry Manual (Maclean Hunter Publishing Company, 1994), the Gulf Coast basin produces about 57 million short tons of lignite annually. The state of Texas ranks number 6 in coal production in the United States. Most of the lignite is used for electric power generation in mine-mouth power plant facilities. In recent years, particular interest has been given to lignite quality and the distribution and concentration of about a dozen trace elements that have been identified as potential hazardous air pollutants (HAPs) by the 1990 Clean Air Act Amendments. As pointed out by Oman and Finkelman (1994), Gulf Coast lignite deposits have elevated concentrations of many of the HAPs elements (Be, Cd, Co, Cr, Hg, Mn, Se, U) on a as-received gm/mmBtu basis when compared to other United States coal deposits used for fuel in thermo-electric power plants. Although regulations have not yet been established for acceptable emissions of the HAPs elements during coal burning, considerable research effort has been given to the characterization of these elements in coal feed stocks. The general purpose of the present field trip and of the accompanying collection of papers is to investigate how various aspects of east Texas lignite geology might collectively influence the quality of the lignite fuel. We hope that this collection of papers will help future researchers understand the complex, multifaceted interrelations of coal geology, petrology, palynology and coal quality, and that this introduction to the geology of the lignite deposits of east Texas might serve as a stimulus for new ideas to be applied to other coal basins in the U.S. and abroad.

  3. Wind Erosion and Dune Formation on High Frozen Bluffs

    NASA Technical Reports Server (NTRS)

    Marsh, W. M.; Marsh, B. D.

    1984-01-01

    Frost penetration increases upslope on barren, windswept bluffs in cold environments. Along the south shore of Lake Superior, near the brow of 100 m high bluffs it typically exceeds 5 m. Frost increases the shear strength of damp sand to a level comparable to that of concrete, making winter slopes highly stable despite undercutting by waves and ground-water sapping along the footslope. Sublimation of interparticle ice in the slope face increases with wind speed and lower vapor pressures. The cold and dry winter winds of Lake Superior ablate these slopes through loss of binding ice. Wind erosion rates, based on measurements of sand accumulation on the forest floor downwind of the brow, show most airborne sand falls out within several meters of the brow, forming a berm 1 to 3 m high after many years. The spatial pattern of sand deposition, however, varies considerably over distances of several hundred meters along the top bluffs in response to frost conditions and the build-up of gravel lag on the slope face, sand exposure from mass movements, and local aerodynamics of the crest slope. The formation of perched sand dunes in the Great Lakes region is clearly related to wind erosion of sand from high bluffs in winter. Broadly similar processes may operate on Mars.

  4. Stratigraphy and Facies of Cretaceous Schrader Bluff and Prince Creek Formations in Colville River Bluffs, North Slope, Alaska

    USGS Publications Warehouse

    Flores, Romeo M.; Myers, Mark D.; Houseknecht, David W.; Stricker, Gary D.; Brizzolara, Donald W.; Ryherd, Timothy J.; Takahashi, Kenneth I.

    2007-01-01

    Stratigraphic and sedimentologic studies of facies of the Upper Cretaceous rocks along the Colville River Bluffs in the west-central North Slope of Alaska identified barrier shoreface deposits consisting of vertically stacked, coarsening-upward parasequences in the Schrader Bluff Formation. This vertical stack of parasequence deposits represents progradational sequences that were affected by shoaling and deepening cycles caused by fluctuations of sea level. Further, the vertical stack may have served to stabilize accumulation of voluminous coal deposits in the Prince Creek Formation, which formed braided, high-sinuosity meandering, anastomosed, and low-sinuosity meandering fluvial channels and related flood plain deposits. The erosional contact at the top of the uppermost coarsening-upward sequence, however, suggests a significant drop of base level (relative sea level) that permitted a semiregional subaerial unconformity to develop at the contact between the Schrader Bluff and Prince Creek Formations. This drop of relative sea level may have been followed by a relative sea-level rise to accommodate coal deposition directly above the unconformity. This rise was followed by a second drop of relative sea level, with formation of incised valley topography as much as 75 ft deep and an equivalent surface of a major marine erosion or mass wasting, or both, either of which can be traced from the Colville River Bluffs basinward to the subsurface in the west-central North Slope. The Prince Creek fluvial deposits represent late Campanian to late Maastrichtian depositional environments that were affected by these base level changes influenced by tectonism, basin subsidence, and sea-level fluctuations.

  5. Depositional environments and reservoir properties of the upper Queen Formation, Concho Bluff and Concho Bluff North fields, Midland basin, Texas

    SciTech Connect

    Mazzullo, J.; Newsom, D.; Harper, J.; McKone, C.; Price, B. )

    1992-04-01

    The upper Queen Formation (Upper Permian) in Concho Bluff and Concho Bluff North fields (Crane, Upton, and Ector counties, Texas) consists of four thick (6-11 m) clastic members separated by evaporite members, and contains several major sandstone reservoirs. A study of cores and logs from the upper Queen was done to determine its depositional environments and the properties of its sandstone reservoirs. Four facies are present in the upper Queen. Facies 1 consists of planar- and wavy-laminated fine and very fine sandstones and silty sandstones deposited in fluvial sandflats and delta-plains. Facies 2 consists of wavy-laminated siltstones and haloturbated mudstones with anhydrite nodules deposited in subaqueous prodelta environments and subaerial saline mudflats. Facies 3 consists of well-sorted fine to very fine sandstones with horizontal and inclined planar laminae deposited in eolian sand sheets. Facies 4 consists of massive to laminated halite and anhydrite deposited in hypersaline playas. The vertical sequence of these facies indicates that the upper Queen was deposited during four cycles of fan-delta progradation into and retreat from coastal-plain playas during a sea level lowstand in the Midland basin. The sandstones of the fluvial sandflat and eolian sand-sheet facies constitute the reservoirs of the upper Queen in the fields. The average cumulative thickness of these facies is 8 m, and the fields average 16% porosity and 40-50 md of permeability. The remaining facies are all nonproductive with averagge porosities of less than 10% and average permeabilities of less than 1 md.

  6. Pumice in the interglacial Whidbey Formation at Blowers Bluff, central Whidbey Island, WA, USA

    USGS Publications Warehouse

    Dethier, D.P.; Dragovich, J.D.; Sarna-Wojcicki, A. M.; Fleck, R.J.

    2008-01-01

    A new 40Ar/39Ar age of 128??9 ka and chemical analyses of pumice layers from interglacial alluvium at Blowers Bluff, Whidbey Island, WA, show that the deposits are part of the Whidbey Formation, a widespread, mainly subsurface unit. Glass chemistry of the dated dacitic pumice does not match any analyzed northern Cascade source, but upper Pleistocene dacites from Glacier Peak and early Pleistocene silicic rocks from the Kulshan caldera are chemically similar. The chemistry of pumiceous dacite in younger units, including the latest Pleistocene Partridge Gravel, is similar to that of the dated material. The deep troughs of the modern northern Puget lowland must have been filled during deposition of the Whidbey Formation, allowing volcanic-rich sediment to reach what is now Whidbey Island. Topographic analysis of LIDAR images demonstrates that extensive erosion occurred during latest Pleistocene ice retreat. The Partridge Gravel likely records subglacial fluvial erosion along an ice tunnel and ice-marginal deposition into adjacent marine waters. Pumice in the Partridge Gravel probably was reworked from stratigraphically and topographically lower deposits, including those at Blowers Bluff. ?? 2007 Elsevier Ltd and INQUA.

  7. Bluff formation and long-term recession rates, southwestern Lake Michigan

    SciTech Connect

    Rovey, C.W. II )

    1992-01-01

    Where eroding cohesive sediments are present, Lake Michigan bluffs range up to 140 ft. in height and expose multiple stratigraphic units. According to the model presented here, bluffs form as a wave cut terrace erodes inland from a point near the original shoreline. The erosion plane is nearly horizontal, in contrast with the eastward dip of the glacial units inherited from underlying bedrock. Therefore, terraces eroding inland (west) produce progressively higher bluffs and expose successively older units at the toe and beneath the lake. This process repeated several times as lake levels sequentially dropped to their modern stage. The initial modern shoreline, and hence the width of the wave cut terrace, was determined from 4 offshore seismic profiles. It is picked as an inflection point in the slope of the lake bed, occurring offshore of dipping reflectors intersecting the lake bottom. The calculated average recession rate over the 2,500 year duration of the modern stage is 5 ft/yr in contrast to average rates of 2 ft/yr measured over the last century. Thus rates decrease through time as the terrace widens and wave energy is damped. By correlating bluff height to amount of recession of modern bluffs, a third rate of 12 ft/yr of the first 800 years of a recession is calculated for relict bluffs formed at the Nipissing II level. The 3 rates define a steeply decaying exponential curve in early stages of bluff retreat, flattening into a nearly linear function after 1,000 years.

  8. Sentinel Hill Core Test 1: Facies Descriptions and Stratigraphic Reinterpretations of the Prince Creek and Schrader Bluff Formations, North Slope, Alaska

    USGS Publications Warehouse

    Flores, Romeo M.; Stricker, Gary D.; Decker, Paul L.; Myers, Mark D.

    2007-01-01

    The Sentinel Hill Core Test 1 well penetrated an intertonguing sequence of (1) the marine Schrader Bluff Formation in the depth intervals 950?1,180 ft and 690?751 ft, which consists of shoreface and offshore deposits that accumulated along a storm-dominated, barred shoreline; and (2) the nonmarine Prince Creek Formation in the depth intervals 751?950 ft and surface to 690 ft, which consists of fluvial channel, crevasse splay, backswamp, and ash fall deposits. The strata range in age from early Campanian to early Maastrichtian. An erosional contact at a depth of 690 ft at the base of the upper unit of the Prince Creek Formation is interpreted as a major regional sequence boundary, and the overlying conglomeratic fluvial channel deposits are interpreted to have accumulated in a paleovalley. In its more proximal reaches along the Colville River, channels of this paleovalley cut down 75 ft into the lowermost Prince Creek Formation and the uppermost Schrader Bluff Formation. Farther offshore, the equivalent surface to the aforementioned paleovalley appears to be a subtle discontinuity between middle and lower Schrader Bluff Formation shelfal marine strata. Still farther offshore, the equivalent paleovalley surface is interpreted as a marine mass-wasting surface that locally cuts through the lowermost Schrader Bluff Formation and into the underlying Seabee Formation.

  9. Bluff evolution along coastal drumlins: Boston Harbor Islands, Massachusetts

    USGS Publications Warehouse

    Himmelstoss, E.A.; FitzGerald, D.M.; Rosen, P.S.; Allen, J.R.

    2006-01-01

    A series of partially drowned drumlins forms the backbone of the inner islands within Boston Harbor. The shoreline of these rounded glacial deposits is composed of actively retreating bluffs formed by continual wave attack. Comparisons of bluffs reveal variability in their height and lateral extent, as well as in the dominant mechanism causing their retreat. Two processes are responsible for bluff erosion and yield distinct bluff morphologies: (1) wave attack undercuts the bluff and causes episodic slumping, yielding planar bluff slopes, and (2) subaerial processes such as rainfall create irregular slopes characterized by rills and gullies. We propose a model of drumlin bluff evolution that is based on processes of erosion and physical characteristics such as bluff height, slope morphology, and the orientation of the bluff with respect to the long axis of the drumlin and its topographic crest. The four phases of drumlin bluff evolution consist of (1) initial formation of bluff, with retreat dominated by wave notching and slumping processes; (2) rill and gully development as bluff heights exceed 10 m and slumped sediment at bluff base inhibits wave attack; (3) return of wave notching and slumping as bluff heights decrease; and (4) final development of boulder retreat lag as last remnants of drumlin are eroded by wave action. These phases capture the important physical processes of drumlin evolution in Boston Harbor and could apply to other eroding coastal drumlin deposits.

  10. 6. SOUTHEAST ABUTMENT AT CALVERT STREET, SHOWING LEON HERMANT ALLEGORICAL ...

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

    6. SOUTHEAST ABUTMENT AT CALVERT STREET, SHOWING LEON HERMANT ALLEGORICAL RELIEF OF TRANSPORTATION BY AUTOMOBILE - Calvert Street Bridge, Spanning Rock Creek & Potomac Parkway, Washington, District of Columbia, DC

  11. 75 FR 66802 - Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-29

    ... COMMISSION Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2... Regulatory Commission (the Commission) has granted the request of Calvert Cliffs Nuclear Power Plant, LLC... Operating License Nos. DPR-53 and DPR-69 for the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and...

  12. 76 FR 39908 - Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-07

    ... COMMISSION Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2.... DPR-53 and DPR-69, for the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (CCNPP), respectively... (ISFSI), currently held by Calvert Cliffs Nuclear Power Plant, LLC as owner and licensed...

  13. Planar Deformation Feature Orientations and Distribution in Quartz Grains from the Carrizo Sand Formation in South Texas: Relation to the Bee Bluff Structure

    NASA Astrophysics Data System (ADS)

    Jurena, D. J.; French, B. M.; Gaffey, M. J.

    2001-03-01

    The Bee Bluff structure has been debated as to its possible impact origin. We have found PDF's there in a higher concentration than in other locations and having dominant orientation patterns consistent with impacts in porous sedimentary rocks.

  14. From Bluff to Backwater

    USGS Multimedia Gallery

    This is an aerial view of Pool 7 of the Mississippi River south of Trempealeau, WI. This photo highlights the different habitats for plants and wildlife from the bluffs that parallel the river to its quiet backwaters. Balanced with that is the fact that the Mississippi River is a commercial highway ...

  15. Historic bluff retreat and stabilization at Flag Harbor, Chesapeake Bay, Maryland

    USGS Publications Warehouse

    Clark, Inga; Larsen, Curtis E.; McRae, Michele

    2002-01-01

    Studies of bluff erosion and slope stability along the western shore of Chesapeake Bay suggest relative evolution from steep, eroding coastal bluffs to stable slopes at angles of repose ca. 35 degrees over decades. Because of the dating methods in those studies, it was impossible to precisely define rates of change. The present study provides historic age control. A pair of small harbor structures were constructed in the early 1950's at Chesapeake Beach, MD to maintain a dredged channel to a small marina occupying a ravine in the Calvert Cliffs. Prior to construction, this section of shoreline was comprised of eroding steep bluffs cut into Miocene-age sediments. Downdrift erosion is now apparent south of the structures as is updrift deposition behind the northern jetty. Since construction the updrift sand body has prograded northward and progressively deposited protective beaches along the toes of the bluffs. Former eroding bluffs nearest the harbor are now stable, vegetated slopes at angles near 35 degrees. Slope angles widen to the north and to the northern limit of the sand body. Beyond this are eroding bluffs standing at angles of 70-80 degrees. The relative time required for eroding bluffs to reach stability is estimated by interpolating the distance and time for the sand body to prograde northward since harbor construction. We measured slope angles at intervals northward from the updrift structure for a distance of 2000 feet. A least squares regression of slope angle vs distance showed progressive decrease in angle from north to south. Actively eroding 70-80 degree bluffs gave way to vegetated, but slumping slopes, and finally to stable 35-degree slopes at the harbor. A relationship between time and distance along the shore allowed us to estimate a stabilization time for this location of 35-40 years. The shortness of this time scale allows us to suggest that attempts to artificially stabilize eroding bluffs along this coast is not a simple task of protecting the toes of slopes from wave action. Once shoreline retreat ends, sloughing of sediment from bluff faces gives way to longer-term landslide processes. The bluff top recedes until a stable 35-degree slope is attained. Thus, simple shoreline protection methods may not preserve property at the bluff edge.

  16. 76 FR 1469 - Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-10

    ... the aquatic or terrestrial habitat in the vicinity of the plant, or to threatened, endangered, or... COMMISSION Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2... Cliffs Nuclear Power Plant, LLC, the licensee, for operation of the Calvert Cliffs Nuclear Power...

  17. Calvert Cliffs zooplankton entrainment study. Final report

    SciTech Connect

    Bradley, B.P.

    1980-01-01

    Entrainment studies to evaluate plant effects on zooplankton were conducted at the Calvert Cliffs Nuclear Plant. Specific effects tested were (a) the spatial and temporal variation of zooplankton density; (b) pump sampling efficiency; (c) delayed mortality; (d) vital staining as an indicator of mortality.

  18. A model of tephra dispersal from an early Palaeogene shallow submarine Surtseyan-style eruption(s), the Red Bluff Tuff Formation, Chatham Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Sorrentino, Leonor; Stilwell, Jeffrey D.; Mays, Chris

    2014-03-01

    The Red Bluff Tuff Formation, an early Palaeogene volcano-sedimentary shallow marine succession from the Chatham Islands (New Zealand), provides a unique framework, in eastern 'Zealandia', to explore tephra dispersal processes associated with ancient small phreatomagmatic explosions (i.e. Surtseyan-style eruptions). Detailed sedimentological mapping, logging and sampling integrated with the results of extensive laboratory analyses (i.e. grain-size, componentry and applied palaeontological methods) elucidated the complex mechanisms of transport and deposition of nine identified resedimented fossiliferous volcaniclastic facies. These facies record the subaqueous reworking and deposition of tephra from the erosion and degradation of a proximal, entirely submerged ancient Surtseyan volcanic edifice (Cone II). South of this volcanic cone, the lowermost distal facies provides significant evidence of deposition as water-supported volcanic- or storm-driven mass flows (e.g. turbidity currents and mud/debris flows) of volcaniclastic and bioclastic debris, whereas the uppermost distal facies exhibit features of tractional sedimentary processes caused by shallow subaqueous currents. Further north, within the proximity of the volcanic edifice, the uppermost facies are represented by an abundant, diverse, large, and well preserved in situ fauna of shallow marine sessile invertebrates (e.g. corals and sponges) that reflect the protracted biotic stabiliszation and rebound following pulsed volcanic events. Over a period of time, these stable and wave-eroded volcanic platforms were inhabited by a flourishing and diversifying marine community of benthic and sessile pioneers (corals, bryozoans, molluscs, brachiopods, barnacles, sponges, foraminifera, etc.). This succession exhibits a vertical progression of sedimentary structures (i.e. density, cohesive and mass flows, and cross-bedding) and our interpretations indicate a shallowing upwards succession. This study reports for the first time mechanisms of degradation of a Surtseyan volcano on Chatham Islands and contributes to a better understanding of complex ancient volcano-sedimentary subaqueous terrains. This model of deposition (i.e. onlapping/overlapping features onto the remains of volcanic edifice(s), a vertical transition of structures from deeper- to shallower-marine environments, disaster faunas and subsequent preferential colonisation of diverse biota, including large in situ sessile invertebrates, on the summit), characterises an extraordinary example to be applied to other ancient subaqueous volcanic environments.

  19. 33 CFR 165.505 - Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Security Zone; Calvert Cliffs... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas Fifth Coast Guard District § 165.505 Security Zone; Calvert Cliffs Nuclear Power Plant,...

  20. 33 CFR 165.505 - Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Security Zone; Calvert Cliffs... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas Fifth Coast Guard District § 165.505 Security Zone; Calvert Cliffs Nuclear Power Plant,...

  1. 33 CFR 165.505 - Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone; Calvert Cliffs... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas Fifth Coast Guard District § 165.505 Security Zone; Calvert Cliffs Nuclear Power Plant,...

  2. 33 CFR 165.505 - Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland. 165.505 Section 165.505 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED...

  3. 33 CFR 165.505 - Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone; Calvert Cliffs... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas Fifth Coast Guard District § 165.505 Security Zone; Calvert Cliffs Nuclear Power Plant,...

  4. A Bluff-Bidding Exercise

    ERIC Educational Resources Information Center

    Meister, J. Patrick

    2011-01-01

    Consider an auction in which one potential buyer wishes to participate, but the other potential buyer would rather the bidding not start. However, once bidding starts, the reluctant firm participates (submits "bluff bids") simply to make the eventual winner pay more. This incentive exists when the marginal effect of the winning bid is to increase

  5. Gosses Bluff impact structure, Australia.

    NASA Technical Reports Server (NTRS)

    Milton, D. J.; Barlow, B. C.; Brown, A. R.; Glikson, A. Y.; Manwaring, E. A.; Moss, F. J.; Sedmik, E. C. E.; Van Son, J.; Brett, R.; Young, G. A.

    1972-01-01

    A comprehensive study has been carried out of the Gosses Bluff structure in Central Australia, which is a typical cryptoexplosion structure. The study included detailed geologic mapping, and seismic reflection and refraction, gravity, aeromagnetic, and ground magnetic surveys. It is concluded that the structure is an eroded crater formed by a single nearly instantaneous shock event, and that the event can be explained only by impact.

  6. 75 FR 21372 - Calvert Social Investment Fund, et al.; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-23

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Calvert Social Investment Fund, et al.; Notice of Application April 19, 2010. AGENCY: Securities... invest in certain financial instruments. Applicants: Calvert Social Investment Fund (the...

  7. Red Bluff, Marion County, Mississippi: a Citronelle braided-stream deposit

    SciTech Connect

    Smith, M.L.; Meylan, M.A.

    1983-09-01

    Red Bluff is an erosional escarpment located on the western margin of the Pearl River flood plain in northwestern Marion County, Mississippi. The sand grains are composed primarily of quartz, with small amounts of heavy minerals and feldspar. The gravel is composed of varying percentages of chert, flint, jasper, rip-up clasts, quartz, and tripoli, including a small fraction of silicified Paleozoic fossils. Grain-size analysis of the sediment and investigation of the sedimentary structures suggest a braided-fluvial environment of deposition. The most conspicuous sedimentary structures at Red Bluff are graded bedding, low-angle to medium-angle cross-bedding, and well-developed paleochannels. A statistical comparison (discriminant analysis) of the seven most abundant heavy minerals of Red Bluff, with the same suite of heavy minerals found at the type section of the Citronelle Formation (Pliocene-Pleistocene), and outcrops of a known Miocene coarse clastic unit indicates a correlation of Red Bluff to the Citronelle Formation. These heavy minerals are kyanite, staurolite, rutile, tourmaline, zircon, black opaques (primarily ilmenite and magnetite), and white opaques (primarily leucoxene). The suite of heavy minerals present at Red Bluff belongs to the east Gulf province. This metamorphic assemblage of heavy minerals implies the source area of the sediments at Red Bluff to be the southern Appalachians. The silicified pebble-size Devonian-Mississippian fossils were derived most likely from formations flanking the southern Appalachians in northern Alabama.

  8. Calvert Cliffs RELAP5/MOD3/SCDAP plant deck

    SciTech Connect

    Hendrix, C.E.; Determan, J.C.

    1992-12-01

    This report documents the development of a RELAP5/MOD3/SCDAP input deck for the Calvert Cliffs nuclear power plant. Through the addition of SCDAP inputs, NPA interactive capabilities, and significant nodalization enhancements the range of applicability; of this input deck has been greatly increased.

  9. Conversations with Rep. Ken Calvert. Interview by Frank Sietzen Jr.

    PubMed

    Calvert, Ken

    2005-07-01

    Rep. Calvert, chair of the House aeronautics and space subcommittee of the Science Committee, answers questions related to priorities for space in the current congressional session: the Vision for Space Exploration, development of the Crew Exploration Vehicle (CEV) and other heavy-lift launch vehicles, entrepreneurial alliances in the space transportation industry, the U.S. aerospace industry, space tourism, entrepreneurs and NASA, U.S. aeronautics research, a service mission to the Hubble Space Telescope, and priority military space programs. PMID:16044613

  10. Aerodynamics of two-dimensional slotted bluff bodies

    SciTech Connect

    Takahashi, F.; Higuchi, H.

    1988-04-30

    Aerodynamic characteristics of two-dimensional, slotted bluff bodies were experimentally investigated. Flow visualizations, base pressure measurements, mean velocity vector measurements, and drag force measurements were conducted to analyze effects of spacing ratio (i.e., porosity), curvature, and vent. Low porosity model configurations produced stable near-wake patterns with enhanced vortex sheddings of overall wake formations. Model curvature reduced drag forces and weakened the vortex sheddings. Stabilizing effect of curvature on the near-wake patterns was also found. A vent combined with large model curvature was found to control drag force effectively, as well as suppressing vortex sheddings. 10 refs., 52 figs., 1 tab.

  11. 78 FR 41397 - Moss Bluff Hub, LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ... Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Filing Take notice that on June 28, 2013, Moss Bluff Hub, LLC (Moss Bluff) filed a revised Statement of Operating Conditions (SOC) pursuant to sections 284.123 and 284.224 of the Commission's regulations, (18 CFR 284.123 and 284.224). Moss...

  12. 77 FR 70431 - Moss Bluff Hub, LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Filing Take notice that on November 15, 2012, Moss Bluff Hub, LLC, (Moss Bluff) filed to revise its Statement of Operating Conditions (SOC)...

  13. Particle size and X-ray analysis of Feldspar, Calvert, Ball, and Jordan soils

    NASA Technical Reports Server (NTRS)

    Chapman, R. S.

    1977-01-01

    Pipette analysis and X-ray diffraction techniques were employed to characterize the particle size distribution and clay mineral content of the feldspar, calvert, ball, and jordan soils. In general, the ball, calvert, and jordan soils were primarily clay size particles composed of kaolinite and illite whereas the feldspar soil was primarily silt-size particles composed of quartz and feldspar minerals.

  14. 77 FR 34093 - License Renewal for Calvert Cliffs Nuclear Power Plant, LLC's

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-08

    ... COMMISSION License Renewal for Calvert Cliffs Nuclear Power Plant, LLC's AGENCY: Nuclear Regulatory... Cliffs Nuclear Power Plant site near Lusby, Maryland. The NRC has prepared an Environmental Assessment... dated September 17, 2010, Calvert Cliffs Nuclear Power Plant, LLC (CCNPP) submitted an application...

  15. The Hydrogen Economy as a Technological Bluff

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2006-01-01

    The hydrogen economy is a technological bluff in its implied assurance that, despite the accelerating pace at which we are depleting the remaining half of our fossil fuels, our energy future is secure. Elementary thermodynamic considerations are developed to show that a hydrogen economy is about as feasible as a perpetual motion machine. Hydrogen…

  16. The Hydrogen Economy as a Technological Bluff

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2006-01-01

    The hydrogen economy is a technological bluff in its implied assurance that, despite the accelerating pace at which we are depleting the remaining half of our fossil fuels, our energy future is secure. Elementary thermodynamic considerations are developed to show that a hydrogen economy is about as feasible as a perpetual motion machine. Hydrogen

  17. Interactions of bluff-body obstacles with turbulent airflows affecting evaporative fluxes from porous surfaces

    NASA Astrophysics Data System (ADS)

    Haghighi, Erfan; Or, Dani

    2015-11-01

    Bluff-body obstacles interacting with turbulent airflows are common in many natural and engineering applications (from desert pavement and shrubs over natural surfaces to cylindrical elements in compact heat exchangers). Even with obstacles of simple geometry, their interactions within turbulent airflows result in a complex and unsteady flow field that affects surface drag partitioning and transport of scalars from adjacent evaporating surfaces. Observations of spatio-temporal thermal patterns on evaporating porous surfaces adjacent to bluff-body obstacles depict well-defined and persistent zonation of evaporation rates that were used to construct a simple mechanistic model for surface-turbulence interactions. Results from evaporative drying of sand surfaces with isolated cylindrical elements (bluff bodies) subjected to constant turbulent airflows were in good agreement with model predictions for localized exchange rates. Experimental and theoretical results show persistent enhancement of evaporative fluxes from bluff-rough surfaces relative to smooth flat surfaces under similar conditions. The enhancement is attributed to formation of vortices that induce a thinner boundary layer over part of the interacting surface footprint. For a practical range of air velocities (0.5-4.0 m/s), low-aspect ratio cylindrical bluff elements placed on evaporating sand surfaces enhanced evaporative mass losses (relative to a flat surface) by up to 300% for high density of elements and high wind velocity, similar to observations reported in the literature. Concepts from drag partitioning were used to generalize the model and upscale predictions to evaporation from surfaces with multiple obstacles for potential applications to natural bluff-rough surfaces.

  18. ORAM-SENTINEL development at Calvert Cliffs. Final report

    SciTech Connect

    1998-05-01

    Baltimore Gas and Electric, in cooperation with EPRI, has installed ORAM-SENTINEL{trademark} software at Calvert Cliffs Nuclear Power Plant. This software incorporates models of the safety and support systems that are used to display the defense-in-depth present in the plant and a quantitative assessment of plant risks during proposed on-line maintenance. During 1997, Baltimore Gas and Electric personnel became familiar with the formal computerized Safety Assessment process associated with on-line and outage maintenance. The report describes the motivation for and the development of ORAM-SENTINEL software. It describes generation of Safety Function Assessment Trees and Plant Transient Assessment Trees and their use in evaluating the level of defense-in-depth of key plant safety functions and plant susceptibility to critical transient events. To show decreasing safety conditions, their results are displayed by color indicators ranging from green through yellow and orange to red. The report describes use of the Calvert Probabilistic Safety Assessment with ORAM-SENTINEL code to calculate an instantaneous core damage frequency and the criteria by which this frequency is translated to a color indicator.

  19. Geology and paleoecology of the Cottonwood Creek delta in the Eocene Tipton Tongue of the Green River Formation and a mammalian fauna from the Eocene Cathedral Bluffs Tongue of the Wasatch Formation, Southeast Washakie Basin, Wyoming

    SciTech Connect

    Roehler, H.W.; Hanley, J.H.; Honey, J.G.

    1988-01-01

    Nonmarine mollusks are used to interpret paleoenvironments and patterns of sedimentation of a fan delta on the east margin of Eocene Lake Gosiute. The delta is composed of a lens of quartzose sandstone intertongued with oil shale. Delta morphology is illustrated by cross sections and paleogeographic maps. A fossil fauna representing five mammalian orders is described and used to establish the age of parts of the Wasatch and Green River formations. There are three chapters in this bulletin.

  20. 76 FR 10581 - Moss Bluff Hub, LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Filing Take notice that on February 11, 2011, Moss Bluff Hub, LLC filed to revise its Statement of General Terms and Standard Operating Conditions...

  1. 78 FR 21930 - Moss Bluff Hub, LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Filing Take notice that on March 29, 2013, Moss Bluff Hub, LLC filed to revise its Statement of Operating Conditions to modify Sections 3.4.4,...

  2. Bluff Body Flow Control Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Thomas, Flint

    2005-11-01

    In this study, the use of single dielectric barrier discharge plasma actuators for the control of bluff body flow separation is investigated. In particular, surface mounted plasma actuators are used to reduce both drag and unsteady vortex shedding from circular cylinders in cross-flow. It is demonstrated that the plasma-induced surface blowing gives rise to a local Coanda effect that promotes the maintenance of flow attachment. Large reductions in vortex shedding and drag are demonstrated for Reynolds numbers 10^410^5. Both steady and unsteady plasma-induced surface blowing is explored. Results are presented from experiments involving both two and four surface mounted actuators.

  3. Map showing recent and historic landslide activity on coastal bluffs of Puget Sound between Shilshole Bay and Everett, Washington

    USGS Publications Warehouse

    Baum, R.L.; Harp, E.L.; Hultman, W.A.

    2000-01-01

    Many landslides occurred on the coastal bluffs between Seattle and Everett, Washington during the winters of 1996 and 1997. Shallow earth slides and debris flows were the most common, but a few deep-seated rotational earth slides also occurred. The landslides caused significant property damage and interfered with rail traffic; future landslides in the area pose significant hazards to property and public safety. Field observations indicate that ground-water seepage, runoff concentration, and dumping at the tops of the bluffs all contributed to instability of the bluffs. Most landslides in the study area occurred in colluvium, residuum, and landslide deposits derived from the Vashon Drift, particularly the advance outwash. In the northern part of the area, colluvium derived from the Pleistocene Whidbey Formation was also involved in shallow landslides. Comparison of recent activity with historic records in the southern part of the map area indicates that landslides tend to occur in many of the same areas as previous landslides.

  4. 77 FR 1748 - Atomic Safety and Licensing Board; Calvert Cliffs 3 Nuclear Project, LLC, and UniStar Nuclear...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-11

    ... Meetings/Hearings, 66 FR 31,719 (June 12, 2001) [hereinafter Meeting Security Guidelines]. All individuals... COMMISSION Atomic Safety and Licensing Board; Calvert Cliffs 3 Nuclear Project, LLC, and UniStar Nuclear... Calvert Cliffs 3 Nuclear Project, L.L.C., and UniStar Nuclear Operating Services, L.L.C. (Applicants)...

  5. 78 FR 4467 - UniStar Nuclear Energy, Combined License Application for Calvert Cliffs Power Plant, Unit 3...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-22

    ... COMMISSION UniStar Nuclear Energy, Combined License Application for Calvert Cliffs Power Plant, Unit 3, Exemption 1.0 Background UniStar Nuclear Energy (UNE), on behalf of Calvert Cliffs Nuclear Project, LLC and... Register notice (FR) 76 FR 81994 (December 29, 2011). 2.0 Request/Action The regulations specified in...

  6. 76 FR 29279 - Calvert Cliffs 3 Nuclear Project, LLC and Unistar Nuclear Operating Services, LLC; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-20

    ... Availability of the Final Environmental Impact Statement for the Combined License Application for Calvert... inform the public that NUREG-1936, ``Environmental Impact Statement for the Combined License for the... impact statement (EIS), NUREG- 1936, for the Calvert Cliffs Nuclear Power Plant (CCNPP), Unit 3...

  7. 77 FR 10784 - Calvert Cliffs Nuclear Power Plant, LLC; Notice of Withdrawal of Application for Amendment to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... COMMISSION Calvert Cliffs Nuclear Power Plant, LLC; Notice of Withdrawal of Application for Amendment to... of Calvert Cliffs Nuclear Power Plant, LLC, the licensee, to withdraw its application dated October... of Amendment published in the Federal Register on April 19, 2011 (76 FR 21919). However, by...

  8. Evaluation of In Situ Combustion for Schrader Bluff

    SciTech Connect

    Sarathi, P.; Strycker, A.; Wang, S.

    1999-03-11

    The focus of this report is on the results related to evaluation of in situ combustion processes applied to Schrader Bluff. Initially, overall screening processes were applied to determine which of the EOR methods, were most appropriate for Schrader Bluff. In situ combustion was among the methods considered potentially favorable and was evaluated further. Laboratory scale tube runs were conducted to determine if the kinetic parameters for the crude oil were favorable. Additional sensitivity studies were conducted to evaluate the recovery potential. Described in this report are the results of the (1) initial screening,(2) experimental tube runs, and (3) simulation sensitivity studies as related to in situ combustion in Schrader Bluff.

  9. Overview from bluff east of facility. Note buildings #35 (left). ...

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

    Overview from bluff east of facility. Note buildings #35 (left). #33 (center), and #31 A (right) VIEW WEST - Department of Energy, Grand Junction Office, 2597 B3/4 Road, Grand Junction, Mesa County, CO

  10. National Uranium Resource Evaluation: Poplar Bluff Quadrangle, Arkansas and Missouri

    SciTech Connect

    Gustavson, J.B.

    1982-08-01

    Uranium resources of the Poplar Bluff Quadrangle, in southeastern Missouri and northeastern Arkansas, were evaluated to a depth of 1500 m using all available surface and subsurface geologic information. No uranium occurrences had been reported. On the surface, a scintillometer survey and a geochemical sampling program were conducted and these data, as well as data from the Hydrogeochemical and Stream Sediment Reconnaissance program, were evaluated for anomalous radioactivity and uranium occurrences. The subsurface was evaluated for favorability using gamma-ray logs, descriptive logs prepared from analyses of well sample cuttings, and previously published and new groundwater sample data. One area of uranium favorability was delineated within the quadrangle. The basis for delineation included uranium source, medium of transportation, host rock, and precipitating conditions. This area lies in the delta-platform facies of the Cretaceous McNairy Sand. No uranium occurrences were found within the favorable area, probably because of limited subsurface data. Geologic units considered unfavorable include all Quaternary, Tertiary, and Cretaceous (except the McNairy Sand) formations, and all Paleozoic rocks extending to the Precambrian basement rocks.

  11. 75 FR 60147 - Calvert Cliffs Nuclear Power Plant, LLC; Independent Spent Fuel Storage Installation; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-29

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Calvert Cliffs Nuclear Power Plant, LLC; Independent Spent Fuel Storage Installation; Notice of Issuance of Amendment to Materials License No. SNM-2505 AGENCY: Nuclear Regulatory Commission. ACTION: Notice of Issuance of Amendment to...

  12. 78 FR 23563 - LWD, Inc. Superfund Site; Calvert City, Marshall County, Kentucky; Notice of Settlement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ...Under 122(h) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the United States Environmental Protection Agency has entered into a settlement with one hundred twenty-five (125) parties and nineteen (19) Federal Agencies addressing past costs concerning the LWD, Inc., Superfund Site located in Calvert City, Marshall County, Kentucky. The settlement addresses......

  13. Disposal of chemical agents and munitions stored at Pine Bluff Arsenal, Pine Bluff, Arkansas

    SciTech Connect

    Ensminger, J.T.; Hillsman, E.L.; Johnson, R.D.; Morrisey, J.A.; Staub, W.P.; Boston, C.R.; Hunsaker, D.B.; Leibsch, E.; Rickert, L.W.; Tolbert, V.R.; Zimmerman, G.P.

    1991-09-01

    The Pine Bluff Arsenal (PBA) near Pine Bluff, Arkansas, is one of eight continental United States (CONUS) Army installations where lethal unitary chemical agents and munitions are stored and where destruction of agents and munitions is proposed under the Chemical Stockpile Disposal Program (CSDP). The chemical agent inventory at PBA consists of approximately 12%, by weight, of the total US stockpile. The destruction of the stockpile is necessary to eliminate the risk to the public from continued storage and to dispose of obsolete and leaking munitions. In 1988 the US Army issued a Final Programmatic Environmental Impact Statement (FPEIS) for the CSDP that identified on-site disposal of agents and munitions as the environmentally preferred alternative (i.e., the alternative with the least potential to cause significant adverse impacts). The purpose of this report is to examine the proposed implementation of on-site disposal at PBA in light of more recent and more detailed data than those on which the FPEIS is based. New population data were used to compute fatalities using the same computation methods and values for all other parameters as in the FPEIS. Results indicate that all alternatives are indistinguishable when the potential health impacts to the PBA community are considered. However, risks from on-site disposal are in all cases equal to or less than risks from other alternatives. Furthermore, no unique resources with the potential to prevent or delay implementation of on-site disposal at PBA have been identified.

  14. Gas Turbine Engine Staged Fuel Injection Using Adjacent Bluff Body and Swirler Fuel Injectors

    NASA Technical Reports Server (NTRS)

    Snyder, Timothy S. (Inventor)

    2015-01-01

    A fuel injection array for a gas turbine engine includes a plurality of bluff body injectors and a plurality of swirler injectors. A control operates the plurality of bluff body injectors and swirler injectors such that bluff body injectors are utilized without all of the swirler injectors at least at low power operation. The swirler injectors are utilized at higher power operation.

  15. 3. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W ...

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

    3. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W of Ms. 25 on dirt road 2.5 mi. N of Bull Mtn. Cr. View from S side of E approach. Sarcone Photography, Columbus, Ms. September 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  16. 4. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W ...

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

    4. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W of Ms. 25 on dirt road 2.5 mi. N of Bull Mtn. Cr. View from N, wide angle. Sarcone Photography, Columbus, Ms. September 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  17. 5. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W ...

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

    5. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W of Ms. 25 on dirt road 2.5 mi. N of Bull Mtn. Cr. View of underside from NE shore, showing lower panel point, lateral bracing. Sarcone Photography, Columbus, Ms. September 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  18. 1. IRONWOOD BLUFFS BRIDGE Tombigbee R. MISSISSIPPI, ITAWAMBA CO. One ...

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

    1. IRONWOOD BLUFFS BRIDGE Tombigbee R. MISSISSIPPI, ITAWAMBA CO. One mile W of Ms. 25 on dirt road 2.5 mi. N of Bull Mtn. Cr. Detail of upper panel point, showing components of members. Sarcone Photography, Columbus, Ms. September 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  19. 2. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W ...

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

    2. IRONWOOD BLUFFS BRIDGE MISSISSIPPI, ITAWAMBA CO. One mile W of Ms. 25 on dirt road 2.5 mi. N of Bull Mtn. Cr. Oblique view of N truss from E end. Sarcone Photography, Columbus, Ms. September 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  20. Overview of the Grand Junction Office from Bluff east of ...

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

    Overview of the Grand Junction Office from Bluff east of facility. Note Buildings #35. #33 and #31A in lower left of photograph. VIEW WEST - Department of Energy, Grand Junction Office, 2597 B3/4 Road, Grand Junction, Mesa County, CO

  1. 78 FR 33121 - Staff Requirements-SECY-12-0168-Calvert Cliffs 3 Nuclear Project, LLC & UniStar Nuclear Operating...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-03

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Staff Requirements--SECY-12-0168--Calvert Cliffs 3 Nuclear Project, LLC & UniStar Nuclear.... On March 11, 2013, in SRM-12-0168, ``Calvert Cliffs 3 Nuclear Project, LLC & UniStar...

  2. Measurements of aerodynamic forces on unsteadily moving bluff parachute canopies

    NASA Astrophysics Data System (ADS)

    Cockrell, D. J.; Harwood, R. J.; Shen, C. Q.

    1987-06-01

    Equations which describe the unsteady motion of bluff bodies through fluids contain certain components, termed added mass coefficients, which can only be determined by experiment. From the solutions to such equations the ways in which the shapes of parachute canopies influence the frequency of their oscillatory motion in pitch and their corresponding damping rates are required. Although a full-scale parachute canopy descends through air, oscillating in pitch as it does, experiments necessary to determine these added mass coefficients have been performed under water, using for this purpose a large ship tank from the towing carriage of which the model parachute canopies were suspended. These experiments showed that the added mass coefficients for bluff parachute canopies differed appreciably from their corresponding potential flow values. The latter were obtained from the analysis of inviscid, fluid flow around regular shapes which were representative of those parachute canopies. The significance for the prediction of the parachute's dynamic behavior in pitch is outlined.

  3. Bluff-body flow simulations using vortex methods

    NASA Astrophysics Data System (ADS)

    Akbari, Mohammad Hadi

    Incompressible, viscous, two-dimensional unsteady flows over bluff bodies are simulated via the use of vortex methods. The vorticity domain is discretized into a number of Lagrangian point vortices. The vorticity transport equation is split into convection and diffusion parts, and each part is solved sequentially, rather than simultaneously, in each time step. The convection equation is solved using a ``vortex-in-cell'' method, and the diffusion equation is either simulated by a random walk method, or solved using a finite-difference ADI scheme. New vorticity is created on the body surface during each time step in order to satisfy the no-slip boundary condition. The no-flow boundary condition is satisfied through proper adjustment of the stream- function on the body surface. Impulsively started flow over an isolated circular cylinder is simulated, and early stages of flow development are studied. Also, the variation of force coefficients and vortex shedding frequency with Reynolds number for fully-developed flows are obtained. Transverse oscillations of a circular cylinder in a cross-flow are investigated, and a lock-in diagram is obtained. Effects of the frequency and amplitude of oscillation on force coefficients and Strouhal frequency are studied. In-line oscillations of a circular cylinder are also simulated, and a similar investigation is performed. Unsteady flow over elliptic cylinders at high angles of attack is simulated. A conformal transformation is used to map the body onto a unit circle, and computations are conducted in the transformed plane. Detailed information on the velocity and vorticity fields around stationary and pitching elliptic cylinders are given. The effects of several parameters on the flow field are investigated. The dynamic stall flow over a pitching NACA 0012 airfoil is simulated. A similar conformal transformation to that employed for the elliptic cylinder is also used in this case. The process of flow separation, vortex formation and release, and flow reattachment during pitching cycles are studied, through streamline and vorticity contour plots. Hysteresis loops for the force and pitching moment coefficients are obtained, and the effects of several parameters on the dynamic stall characteristics of the airfoil are investigated.

  4. The recirculation dynamics of bluff body stabilized premixed combustion.

    NASA Astrophysics Data System (ADS)

    Soteriou, Marios

    2005-11-01

    Bluff body stabilized premixed combustion is present in many power generation and propulsion systems such as gas turbines and afterburners. In this environment, flow recirculation behind the bluff body provides low speed, hot products that act as an ignition source for the incoming reactants and help anchor the flame. Beyond this coarse phenomenological description, however, understanding of bluff body flame stabilization via recirculation is rather limited. This is particularly so for non-swirling systems which are the focus of this work. To investigate this problem we use numerical simulation. The computational model is Lagrangian, employing the vortex element method for the simulation of the low Mach number exothermic flow field and a G-equation flamesheet for the reacting field. Numerical results are contrasted to experimental and analytical findings to demonstrate the ability of the model to reproduce the flow unsteady behavior in both the reacting and non-reacting environments. Analysis focuses on the differences in the recirculation dynamics between the reacting (symmetric shedding) and non reacting (asymmetric shedding) flow. It is shown that these differences are sensitive to both internal flow parameters such as heat release and flame speed but also to boundary conditions such as inlet temperature and confinement.

  5. Bluff Body Fluid Interactions Modelling for Micro Energy Harvesting Application

    NASA Astrophysics Data System (ADS)

    Bhuyan, M. S.; Majlis, B. Y.; Othman, M.; Ali, Sawal H. Md; Kalaivani, C.; Islam, S.

    2013-04-01

    In this paper, we have presented a MEMS-based piezoelectric fluid-flow based micro energy harvester. The design and modelling of the energy harvester structure was based on a piezoelectric cantilever affixed to a bluff-body. In a cross fluid flow, pressure in the flow channel, in the wake of the bluff body, fluctuates with the same frequency as the pressure variation caused by the Kármán Vortex Street. This fluctuation of pressure in the flow channel causes the piezoelectric cantilever, trailing the bluff-body, to vibrate in a direction normal to the fluid flow direction. COMSOL finite element analysis software are used for the evaluation of various mechanical analysis of the micro energy harvester structure like, physical the Stress and Strain state in the cantilever structures, Eigen frequency Analysis, Transient analysis to demonstrate the feasibility of the design. Detailed steps of modelling and simulation results of the uniform cantilever were explained. The results confirm the probability of the fluid flow based MEMS energy harvester.

  6. Long-term benthic monitoring programs near the Morgantown and Calvert Cliffs power plants. Annual report, 1980-1984

    SciTech Connect

    Holland, A.F.; Shaughnessy, A.T.; Hiegel, M.H.; Stroup, C.F.

    1985-07-01

    Macrobenthos and physical/chemical factors known to affect them were monitored near Calvert Cliffs on the mainstem of the Chesapeake Bay (1971-1984). These data, along with data collected near Morgantown on the Potomac River (1980-1984), were used to quantify variation in macrobenthic abundance due to spatial patterns, season, year, and power plant operations. Macrobenthos were persistent within bounds determined by year-to-year variation in salinity and dissolved oxygen. All species responded to anoxia by declines in abundance. Species that prefer high mesohaline salinity increased in abundance at Calvert Cliffs; freshwater and estuarine species increased in abundance at Morgantown.

  7. Characterizing Morphology and Erosional Trends of Permafrost Bluffs, Barter Island, Alaska

    NASA Astrophysics Data System (ADS)

    Gibbs, A.; Erikson, L. H.; Jones, B.; Richmond, B. M.

    2010-12-01

    Recession of coastal permafrost bluffs along portions of the North Slope of Alaska are highly variable, and recent studies have found increased retreat rates since the early 2000s along the western Beaufort Sea coastline, yet the mechanisms and processes driving the increased retreat rates remain poorly understood. The Native village of Kaktovik and adjacent U.S. Air Force radar site are situated on Barter Island and bound by an eroding coastal bluff where attempts to control bluff erosion with shore protection structures were undertaken more than a decade ago. In an effort to gain insight into the physical controls driving or limiting bluff recession in this region, a suite of field data was collected in August 2010 to characterize the beaches, bluffs, and nearshore setting. Data collected at 13 transect locations along the 3 km section of coastal bluffs include general bluff morphology and stratigraphy, detailed surveys of bluff edge and bluff face morphology, sediment grain size of the fronting beach, water/ice content and sediment grain size of the massive ice within the bluffs, and nearshore bathymetry. The bluffs here range in height from a few meters to more than ten meters and consist of a very complex sequence of material ranging from dense marine clay at the base, sands and gravel thought to be of fluvial origin, massive units of sand of unknown origin, massive ice which has recently been interpreted as buried glacial ice, wedge ice, thermokarst cave ice, aeolian silts and sands, and peat. At one site, thermistor arrays were installed to evaluate temperature gradients in response to solar radiation and heat flux transfers through characteristic bluff material. Aerial lidar DEMs obtained in 2009 (USGS) revealed a rise in bluff elevation across the central portion of the island where field observations of bluff stratigraphy showed multi-layered stratification. At the lower elevation outer flanks the exposed bluff face consisted of homogenous layers of sandy-silt below the surface peat layer. Comparison of historical bluff edge lines (1947, 1987, 2003), 2009 lidar derived bluff lines, and differential GPS surveys collected in August 2010 suggest increased erosion rates of the bluff top in recent years near the topographically-higher central portion of the island. Maximum beach widths were observed at the flanks of the island where east-west trending spits have formed, likely by way of longshore transport driven by variations in wave direction at the terminus of the spits. Beach width ranged from a maximum of 80 m at the eastern boundary of the bluffs to no beach in front of the former radar station landfill where shore protection structures are emplaced. Beach surface material consisted of fine sands in the back beach region and gravels to pebble-sized material in the mid-beach and swash zone areas. Primary failure modes of Barter Island bluffs appear to be a combination of thermal degradation and thawing of permafrost in the exposed bluff face, mechanical and thermal niching at the toe, followed by rotational slumping of the higher bluffs near the central portion of the island and block collapse of the lower bluffs at the flanks of the island.

  8. Indicator tests for the creep of rock salt from borehole Moss Bluff 2, Moss Bluff Dome, Texas

    SciTech Connect

    Wawersik, W.R.

    1992-11-01

    Creep tests were performed on a representative sample of rock salt from borehole Moss Bluff 2 (MB2), Moss Bluff dome near Houston, Texas. Moss Bluff 2 is located at the site of a compressed gas storage cavern of Tejas Power Corporation. Four triaxial experiments were conducted at two values of principal stress difference and two representative temperatures. The minimum observed creep rates at the end of each test varied between 5.2{times}10{sup {minus}9} 1/s and 2.14{times}10{sup {minus}8} 1/s. Comparisons of the present results with existing data for rock salt from other locations suggest that the steadystate creep characteristics of MB2 salt, depth 3349 ft (1098.8 m), are intermediate to those measured for the US Strategic Petroleum Reserve at West Hackberry and Bryan Hound, which included the most creep resistant rock salt ever tested at Sandia National Laboratories. Creep parameters are suggested for first-order sensitivity calculations.

  9. Indicator tests for the creep of rock salt from borehole Moss Bluff 2, Moss Bluff Dome, Texas

    SciTech Connect

    Wawersik, W.R.

    1992-11-01

    Creep tests were performed on a representative sample of rock salt from borehole Moss Bluff 2 (MB2), Moss Bluff dome near Houston, Texas. Moss Bluff 2 is located at the site of a compressed gas storage cavern of Tejas Power Corporation. Four triaxial experiments were conducted at two values of principal stress difference and two representative temperatures. The minimum observed creep rates at the end of each test varied between 5.2[times]10[sup [minus]9] 1/s and 2.14[times]10[sup [minus]8] 1/s. Comparisons of the present results with existing data for rock salt from other locations suggest that the steadystate creep characteristics of MB2 salt, depth 3349 ft (1098.8 m), are intermediate to those measured for the US Strategic Petroleum Reserve at West Hackberry and Bryan Hound, which included the most creep resistant rock salt ever tested at Sandia National Laboratories. Creep parameters are suggested for first-order sensitivity calculations.

  10. 76 FR 81994 - UniStar Nuclear Energy; Combined License Application for Calvert Cliffs Nuclear Power Plant, Unit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ... COMMISSION UniStar Nuclear Energy; Combined License Application for Calvert Cliffs Nuclear Power Plant, Unit 3; Exemption 1.0 Background: UniStar Nuclear Energy (UNE) submitted to the U.S. Nuclear Regulatory... in a violation of the Atomic Energy Act of 1954, as amended, or the NRC's regulations. Therefore,...

  11. Thermal Modeling of NUHOMS HSM-15 and HSM-1 Storage Modules at Calvert Cliffs Nuclear Power Station ISFSI

    SciTech Connect

    Suffield, Sarah R.; Fort, James A.; Adkins, Harold E.; Cuta, Judith M.; Collins, Brian A.; Siciliano, Edward R.

    2012-10-01

    As part of the Used Fuel Disposition Campaign of the Department of Energy (DOE), visual inspections and temperature measurements were performed on two storage modules in the Calvert Cliffs Nuclear Power Station’s Independent Spent Fuel Storage Installation (ISFSI). Detailed thermal models models were developed to obtain realistic temperature predictions for actual storage systems, in contrast to conservative and bounding design basis calculations.

  12. 76 FR 53426 - Moss Bluff Hub, LLC; Notice of Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Baseline Filing Take notice that on August 17, 2011, Moss Bluff Hub, LLC submitted a revised Statement of Operating Conditions, that governs...

  13. 75 FR 33799 - Moss Bluff Hub, LLC; Notice of Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moss Bluff Hub, LLC; Notice of Baseline Filing June 8, 2010. Take notice that on June 1, 2010, Moss Bluff Hub, LLC submitted a baseline filing of its Statement of General...

  14. 33 CFR 207.170 - Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170 Navigation and Navigable Waters CORPS OF ENGINEERS..., Moss Bluff, Fla.; pool level. (a) The level of the pool shall normally be maintained at elevation...

  15. 33 CFR 207.170 - Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a)...

  16. 33 CFR 207.170 - Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a)...

  17. 33 CFR 207.170 - Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a)...

  18. Axisymmetric bluff-body drag reduction through geometrical modifications

    NASA Astrophysics Data System (ADS)

    Howard, F. G.; Goodman, W. L.

    1984-08-01

    The effect of shoulder radiusing and grooving (longitudinally or circumferentially) the afterbodies of bluff bodies of reduce the base drag at low speeds is discussed. Shoulder radii as large as 2.75 body diameters are examined. Reynolds number based on body diameter varied from 20,000 to 200,000. Results indicate that increasing the shoulder radius to 2.75 body diameters can reduce the drag levels to those of a streamline body having 67 percent greater fineness ratio. For the relatively sharp shoulder case, body drag reductions as large as 50% are obtained using circumferential or longitudinal grooves.

  19. Monte Carlo simulation for neutrino detection from Minna Bluff, Antarctica

    NASA Astrophysics Data System (ADS)

    Barrella, Taylor; Vieregg, Abigail; Saltzberg, David

    2012-03-01

    We present a simple Monte Carlo simulation for a possible neutrino detection experiment. The detector would be composed of an array of radio antennas on Minna Bluff, Antarctica, designed to detect Cherenkov radiation from ultra-high-energy neutrinos. The simulation generates neutrino interactions in the Ross Ice Shelf below the antennas to determine the expected number of detected events per year. Though the results predict less than one event per year, the detection of tau neutrinos should increase the event rate for detectors embedded in the ice.

  20. Secondary sulfate minerals from Alum Cave Bluff: Microscopy and microanalysis

    SciTech Connect

    Lauf, R.J.

    1997-07-01

    Microcrystals of secondary sulfate minerals from Alum Cave Bluff, Great Smoky Mountains National Park, were examined by scanning electron microscopy and identified by X-ray fluorescence (XRF) in the SEM. Among the samples the author discovered three new rare-earth sulfates: coskrenite-(Ce), levinsonite-(Y), and zugshunstite-(Ce). Other minerals illustrated in this report include sulfur, tschermigite, gypsum, epsomite, melanterite, halotrichite, apjohnite, jarosite, slavikite, magnesiocopiapite, and diadochite. Additional specimens whose identification is more tentative include pickeringite, aluminite, basaluminite, and botryogen. Alum Cave is a ``Dana locality`` for apjohnite and potash alum, and is the first documented North American occurrence of slavikite.

  1. Plasma actuators for bluff body flow control

    NASA Astrophysics Data System (ADS)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding noise. A tandem cylinder configuration with the plasma actuation on the upstream cylinder is investigated using surface dynamic pressure sensors. As a result of the plasma actuation, the surface pressure fluctuations on the downstream cylinder are reduced by about two times at the free-stream velocity of 40 m/s (ReD = 164,000). In addition, this study presents the results of a parametric experimental investigation aimed at optimizing the body force produced by single dielectric barrier discharge (SDBD) plasma actuators used for aerodynamic flow control. A primary goal of the study is the improvement of actuator authority for flow control applications at higher Reynolds number than previously possible. The study examines the effects of dielectric material and thickness, applied voltage amplitude and frequency, voltage waveform, exposed electrode geometry, covered electrode width and multiple actuator arrays. The metric used to evaluate the performance of the actuator in each case is the measured actuator-induced thrust which is proportional to the total body force. It is demonstrated that actuators constructed with thick dielectric material of low dielectric constant and operated at low frequency AC voltage produce a body force that is an order of magnitude larger than that obtained by the Kapton-based actuators used in many previous plasma flow control studies. These actuators allow operation at much higher applied voltages without the formation of discrete streamers which lead to body force saturation.

  2. Coastal erosion: Processes, timing and magnitudes at the bluff toe

    USGS Publications Warehouse

    Carter, C.H.; Guy, D.E., Jr.

    1988-01-01

    Five Lake Erie bluffs (one interlaminated clay and silt, three clay-rich diamicts and one shale) were surveyed at about 2-week intervals and after wind storms for up to 5 years. Erosion of the bluff toes along this low-energy coast occurred during northeast wind storms, which produced surges of up to 1 m and surf-zone waves of up to 1.2 m. Wave impact and/or uprush caused quarrying, which removed most of the toe material, and abrasion. There were from 1 to 23 erosion events/sites, with maximum magnitudes of erosion ranging from 12 to 55 cm/event. Timing and magnitude were linked to erodibility, maximum water level, storm surge, storm duration and beach width. A threshold maximum water level and a threshold surge were necessary for erosion. At these thresholds, the beach was submerged and wave energy was directly expended on the toe. Erosion did not take place when there was shorefast ice or when debris slopes shielded the toe from waves. The originally cohesive toe materials are easily eroded when they weather to an essentially noncohesive state. Wave erosion is the crucial erosion process; removal of material from the toe prevents the development of a stable slope. ?? 1988.

  3. Hydrodynamic Mass of Bluff Bodies with a Cavity

    NASA Astrophysics Data System (ADS)

    Elgabaili, Mohamed; Desabrais, Kenneth; Johari, Hamid

    2012-11-01

    Hydrodynamic mass of an object may be used to compute the contribution of unsteady drag resulting from potential flow. Even though the hydrodynamic mass of certain bluff bodies such as cylinder and sphere have been available from analytical considerations for a long time, there are no analytical solutions for a general bluff body with a cavity such as a cup facing the flow or a round parachute canopy. There is, however, an analytical solution for spherical shells of various concavities. The translational hydrodynamic mass of cups having various depth and thickness as well as round parachute canopies during inflation was computed using a finite element solver. The kinetic energy of the potential flow around the body was used to extract the hydrodynamic mass. Results indicate that the hydrodynamic mass of a cup can be decomposed into two components, the hydrodynamic mass of a cylinder whose axis is aligned with the flow and the mass of fluid within the cup cavity. Similarly, the hydrodynamic mass of a parachute canopy during various stages of inflation may be written as the hydrodynamic mass of a disk having the same area as the projected area of the canopy plus the mass of fluid enclosed by the canopy. Sponsored by the US Army Natick RDEC.

  4. Blowoff dynamics of bluff body stabilized turbulent premixed flames

    SciTech Connect

    Chaudhuri, Swetaprovo; Kostka, Stanislav; Renfro, Michael W.; Cetegen, Baki M.

    2010-04-15

    This article concerns the flame dynamics of a bluff body stabilized turbulent premixed flame as it approaches lean blowoff. Time resolved chemiluminescence imaging along with simultaneous particle image velocimetry and OH planar laser-induced fluorescence were utilized in an axisymmetric bluff body stabilized, propane-air flame to determine the sequence of events leading to blowoff and provide a quantitative analysis of the experimental results. It was found that as lean blowoff is approached by reduction of equivalence ratio, flame speed decreases and the flame shape progressively changes from a conical to a columnar shape. For a stably burning conical flame away from blowoff, the flame front envelopes the shear layer vortices. Near blowoff, the columnar flame front and shear layer vortices overlap to induce high local stretch rates that exceed the extinction stretch rates instantaneously and in the mean, resulting in local flame extinction along the shear layers. Following shear layer extinction, fresh reactants can pass through the shear layers to react within the recirculation zone with all other parts of the flame extinguished. This flame kernel within the recirculation zone may survive for a few milliseconds and can reignite the shear layers such that the entire flame is reestablished for a short period. This extinction and reignition event can happen several times before final blowoff which occurs when the flame kernel fails to reignite the shear layers and ultimately leads to total flame extinguishment. (author)

  5. Pressurized thermal shock evaluation of the Calvert Cliffs Unit 1 Nuclear Power Plant

    SciTech Connect

    Abbott, L

    1985-09-01

    An evaluation of the risk to the Calvert Cliffs Unit 1 nuclear power plant due to pressurized thermal shock (PTS) has been completed by Oak Ridge National Laboratory (ORNL) with the assistance of several other organizations. This evaluation was part of a Nuclear Regulatory Commission program designed to study the PTS risk to three nuclear plants, the other two plants being Oconee Unit 1 and H.B. Robinson Unit 2. The specific objectives of the program were to (1) provide a best estimate of the frequency of a through-the-wall crack in the pressure vessel at each of the three plants, together with the uncertainty in the estimated frequency and its sensitivity to the variables used in the evaluation; (2) determine the dominant overcooling sequences contributing to the estimated frequency and the associated failures in the plant systems or in operator actions; and (3) evaluate the effectiveness of potential corrective measures.

  6. Description of the larva of Argia chelata Calvert, 1902 (Odonata: Coenagrionidae).

    PubMed

    Novelo-Gutiérrez, Rodolfo

    2013-01-01

    The larva of Argia chelata is described and figured. It falls into the group of Argia larvae with a moderately prominent ligula and two palpal seta, but it differs from its closest relatives by having labial palp with 2 setae plus one basal setella; the length of the ligula is 30% of its maximum width; basal tergites (1-5) lacking long, fine setae, mainly on midline; S8-10 mostly dark brown; paraprocts with spiniform setae on basal 0.25 and 0.55 of dorsal and ventral borders, respectively. Larvae were found in 2nd to 4th order shallow streams in cloud forest, crawling among debris, fine sand and mud where the water flow is slow or still, close to the shoreline. The larva is compared with A. lacrimans (Hagen), A. pima Garrison, and A. tonto Calvert, species apparently closely related.  PMID:25113363

  7. Laboratory measurements of upwelled radiance and reflectance spectra of Calvert, Ball, Jordan, and Feldspar soil sediments

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Usry, J. W.; Witte, W. G.; Gurganus, E. A.

    1977-01-01

    An effort to investigate the potential of remote sensing for monitoring nonpoint source pollution was conducted. Spectral reflectance characteristics for four types of soil sediments were measured for mixture concentrations between 4 and 173 ppm. For measurements at a spectral resolution of 32 mm, the spectral reflectances of Calvert, Ball, Jordan, and Feldspar soil sediments were distinctly different over the wavelength range from 400 to 980 nm at each concentration tested. At high concentrations, spectral differences between the various sediments could be detected by measurements with a spectral resolution of 160 nm. At a low concentration, only small differences were observed between the various sediments when measurements were made with 160 nm spectral resolution. Radiance levels generally varied in a nonlinear manner with sediment concentration; linearity occurred in special cases, depending on sediment type, concentration range, and wavelength.

  8. Disposal of chemical agents and munitions stored at Pine Bluff Arsenal, Pine Bluff, Arkansas. Final phase 1, Environmental report

    SciTech Connect

    Ensminger, J.T.; Hillsman, E.L.; Johnson, R.D.; Morrisey, J.A.; Staub, W.P.; Boston, C.R.; Hunsaker, D.B.; Leibsch, E.; Rickert, L.W.; Tolbert, V.R.; Zimmerman, G.P.

    1991-09-01

    The Pine Bluff Arsenal (PBA) near Pine Bluff, Arkansas, is one of eight continental United States (CONUS) Army installations where lethal unitary chemical agents and munitions are stored and where destruction of agents and munitions is proposed under the Chemical Stockpile Disposal Program (CSDP). The chemical agent inventory at PBA consists of approximately 12%, by weight, of the total US stockpile. The destruction of the stockpile is necessary to eliminate the risk to the public from continued storage and to dispose of obsolete and leaking munitions. In 1988 the US Army issued a Final Programmatic Environmental Impact Statement (FPEIS) for the CSDP that identified on-site disposal of agents and munitions as the environmentally preferred alternative (i.e., the alternative with the least potential to cause significant adverse impacts). The purpose of this report is to examine the proposed implementation of on-site disposal at PBA in light of more recent and more detailed data than those on which the FPEIS is based. New population data were used to compute fatalities using the same computation methods and values for all other parameters as in the FPEIS. Results indicate that all alternatives are indistinguishable when the potential health impacts to the PBA community are considered. However, risks from on-site disposal are in all cases equal to or less than risks from other alternatives. Furthermore, no unique resources with the potential to prevent or delay implementation of on-site disposal at PBA have been identified.

  9. Thermal Modeling Studies for Active Storage Modules in the Calvert Cliffs ISFSI

    SciTech Connect

    Adkins, Harold E.; Fort, James A.; Suffield, Sarah R.; Cuta, Judith M.; Collins, Brian A.

    2013-06-14

    Temperature measurements obtained for two storage modules in the Calvert Cliffs Nuclear Power Stations Independent Spent Fuel Storage Installation (ISFSI) as part of the Used Fuel Disposition Campaign of the Department of Energy (DOE) were used to perform validation and sensitivity studies on detailed computational fluid dynamics (CFD) models of the concrete storage modules, including the dry storage canister within the modules. The storage modules in the Calvert Cliffs Nuclear Power Stations ISFSI are a site-specific version of the standard NUHOMS HSM. The two modules inspected each contained a 24P DSC loaded with 24 CE 14x14 spent fuel assemblies. The thermal analysis was performed using the STAR-CCM+ package, and the models developed for the specific ISFSI modules yielded temperature predictions in actual storage conditions for the concrete structure, the DSC and its contents, including preliminary estimates of fuel cladding temperatures for the used nuclear fuel. The results of this work demonstrate that existing CFD modeling tools can be used to obtain reasonable and accurate detailed representations of spent fuel storage systems with realistic decay heat loadings when the model omits specific conservatisms and bounding assumptions normally used in design-basis and safety-basis calculations. This paper presents sensitivity studies on modeling detail (for the storage module and the DSC), boundary conditions, and decay heat load, to evaluate the effect of the modeling approach on predicted temperatures and temperature distributions. Because nearly all degradation mechanisms for materials and structures comprising dry storage and transportation systems are dependent on temperature, accurate characterization of local temperatures and temperature gradients that the various components of these systems will experience over the entire storage period has been identified as a primary requirement for evaluation of very long term storage of used nuclear fuel.

  10. Combustion heat release effects on asymmetric vortex shedding from bluff bodies

    NASA Astrophysics Data System (ADS)

    Cross, Caleb Nathaniel

    2011-07-01

    This thesis describes an investigation of oscillatory combustion processes due to vortex shedding from bluff body flame holders. The primary objective of this study was to elucidate the influence of combustion process heat release upon the Benard-von Karman (BVK) instability in reacting bluff body wakes. For this purpose, spatial and temporal heat release distributions in bluff body-stabilized combustion of liquid Jet-A fuel with high-temperature, vitiated air were characterized over a wide range of operating conditions. Two methods of fuel injection were investigated. In the first method, referred to as close-coupled fuel injection, the fuel was supplied via discrete liquid jets injected perpendicular to the cross-flowing air stream just upstream of the bluff body trailing edge, thereby limiting fuel and air mixing prior to burning. The fuel was introduced well upstream (0.5 m) of the bluff body in the second fuel injection mode, resulting in a well-evaporated and mixed reactants stream. The resulting BVK heat release dynamics were compared between these fuel injection modes in order to investigate their dependence upon the spatial distributions of fuel-air ratio and heat release in the reacting wake. When close-coupled fuel injection was used, the BVK heat release dynamics increased in amplitude with increasing global equivalence ratio, reaching a maximum just before globally rich blow out of the combustion process occurred. This was due to a decrease in fuel entrainment into the near-wake as the fuel spray penetrated further into the cross-flow, which reduced the local heat release and equivalence ratio (indicated by CH* and C2*/CH* chemiluminescence, respectively). As a result, the density gradient across the near-wake reaction zone decreased, resulting in less damping of vorticity due to dilatation. In addition, unburned reactants were entrained into the recirculation zone due to the injection of discrete liquid fuel jets in close proximity to the wake. This reduced the temperature of the recirculating gases further, resulting in large (i.e., near-unity) products-to-reactants density ratios in the near-wake. When the fuel was introduced upstream of the bluff body, the BVK heat release dynamics significantly decreased in amplitude. In this case the fuel was, in all likelihood, fully evaporated and well-mixed with the air prior to burning, resulting in greater amounts of fuel entrainment and subsequent heat release in the near-wake than in the close-coupled fuel injection case. In addition, the heat release was distributed more uniformly across the combustor span, which led to stronger density gradients across the near-wake reaction zone than in close-coupled-fuelled flames due to a lack of reactants entrainment into the recirculation zone. This enhanced the damping of vorticity due to dilatation, which inhibited the formation and shedding of the large-scale, coherent vortices. When the local density gradient was large enough, the BVK instability was completely suppressed. A parallel, linear stability analysis was performed in order to further understand the influence of the near-wake combustion process heat release upon the wake instability characteristics. The results of this analysis indicate that the products-to-reactants density and velocity ratios in the near-wake are the primary parameters controlling the onset of local absolute instability (a necessary condition for the global, BVK instability) in reacting wakes. Upon comparing these results to the measured data, absolute instability was predicted for all operating conditions in which relatively high-amplitude BVK heat release dynamics were observed. This was the case for close-coupled fuel injection at all global equivalence ratios, as well as upstream fuel injection at lean equivalence ratios, due to the low temperature rise across the reacting shear layers in these cases. Only upstream fuel injection at near stoichiometric fuel-air ratios resulted in local products-to-reactants density ratios low enough to suppress absolute instability and, thus, BVK vort

  11. A study of a bluff-body combustor using laser sheet lighting

    NASA Astrophysics Data System (ADS)

    Roquemore, W. M.; Tankin, R. S.; Chiu, H. H.; Lottes, S. A.

    1986-07-01

    Laser sheet lighting is used to study reacting flows with and without heat release in an axisymmetric, unducted and vertically mounted bluff-body combustor. The fuel, which is seeded with titanium tetrachloride vapor, is ejected from a jet located in the center of the bluff-body. The TiCl4 in the dry fuel reacts spontaneously with the water in the annulus air to form titanium dioxide particles. High speed movies and visual observations of vertically and horizontally located sheets of laser light provided remarkably detailed visualization (via Mie scattering) of the vortex dynamics in the near-wake region of the bluff-body.

  12. Jackson Bluff Hydroelectric Project: emergency action plan, City of Tallahassee

    SciTech Connect

    Not Available

    1984-05-01

    Jackson Bluff Dam is located on the Ochlockonee River about 66 miles upstream from its mouth at the Gulf of Mexico and approximately 20 miles west-southwest of the City of Tallahassee. The site is situated in Leon, Gadsden, and Liberty counties. The dam consists of a 3600 ft long earth embankment with the crest at EL. 77 (MSL). About 1000 ft north of the end of the main dam is a saddle dam. The saddle dam is approximately 550 ft long and has crest at EL 72.3 (4.7 ft below the main dam). The gated spillway and the powerhouse are located at the southeast end of the dam. The purpose of the Emergency Action Plan is to specify actions to be taken in the event of flooding of the downstream of the Ochlockonee River due to failure of the dam.

  13. Axisymmetric bluff-body drag reduction using circumferential grooves

    NASA Technical Reports Server (NTRS)

    Howard, F. G.; Goodman, W. L.; Walsh, M. J.

    1983-01-01

    The effect of shoulder radiusing and circumferentially grooving the afterbodies of bluff bodies to reduce the base drag at low speeds is discussed. Shoulder radii as large as 2.75 body diameters are examined. Reynolds number based on body diameter varied from 20,000 to 200,000. Results indicate that increasing the shoulder radius to 2.75 body diameters can reduce the drag levels to those of a streamline body having 67 percent greater fineness ratio. For zero shoulder radius, circumferential grooves were found to be effective in reducing body drag for zero shoulder radius in both laminar and tripped flow. Circumferential grooves on the afterbody with a shoulder radius of one-half the body diameter were only effective in reducing drag for laminar flow.

  14. On point vortex models of exotic bluff body wakes

    NASA Astrophysics Data System (ADS)

    Stremler, Mark A.; Basu, Saikat

    2014-12-01

    Exotic vortex wakes, in which three or more vortices are generated during each shedding cycle, are frequently found in the wake of an oscillating bluff body. Two common examples are P+S wakes (with 3 vortices) and 2P wakes (with 4 vortices). We consider mathematical models of these wakes consisting of N = 3 or 4 point vortices with constant strengths in an inviscid fluid that is otherwise at rest in a singly-periodic domain. By enforcing constraints on the vortex strengths and, in the case of N = 4, on the symmetry of the vortex locations, the mathematical models reduce to integrable Hamiltonian systems. We compare the point vortex trajectories with two exotic wake patterns reported in the literature. Results support the use of point vortex modeling to investigate vortex dynamics in exotic wakes and suggest the need for additional classification of experimental wake patterns.

  15. Visualization of turbulence in flow about a bluff body

    NASA Technical Reports Server (NTRS)

    Sadeh, W. Z.; Brauer, H. J.

    1979-01-01

    A visual diagnostic investigation of turbulence in flow about a circular cylinder was conducted in order to gain a physical insight into the model for the structure of turbulence in flow around a bluff body advanced by the vorticity-amplification theory. A frame-by-frame qualitative and quantitative examination of selected movie strips over time intervals up to more than 800 ms was performed. The selective stretching of cross-vortex tubes, their streamwise tilting, the emergence of an organized turbulent flow pattern near the stagnation zone and the growth of a turbulent boundary layer were clearly revealed by the visualization. In particular, the visualization indicated that the cross-vortex tubes conveyed by the diverging stagnation flow constitute a coherent substructure within the overall turbulent flow that is triggered to its fullest manifestation by the stretching mechanism.

  16. Comparison of active flow control devices on bluff body shapes

    NASA Astrophysics Data System (ADS)

    Haack, Sarah J.; Flatau, Alison B.

    2007-04-01

    Results from experimental studies on the performance of plasma and synthetic jet actuators for active control of flow over a circular cylinder in subcritical flow conditions ranging from a Reynolds Number of 2.5 x 10 4 to 7.3x10 4 are presented. The experiments were conducted at the NASA Langley Research Center in the 20" x 28" Shear Flow Wind Tunnel and the results provide an indication of the effectiveness of, as well as the similarities and differences between these two active flow control (AFC) methods for reducing pressure drag on a bluff body shape. Flows over a cylinder are well understood and in particular flow separation characteristics for cylinders are well documented both experimentally and theoretically. The effect of the flow control devices is quantified by measuring the pressure distribution around the bluff bodies using a multi-port piezoelectric pressure scanner and integrating the distribution for drag analysis. This comparison consists of operating the two types of actuators in the same range of Reynolds Numbers (Re) over the cylinder and for the same actuator angular positions on the cylinder. The applied voltages and frequencies to the actuators varies based on the individual actuator operating conditions. At low Re, the plasma actuators have a strong effect on the pressure distribution reducing the drag up to 32% relative to the drag with no actuators on the surface. The synthetic jet reduces drag up to 25% but with lower voltage and frequency. For both actuator cases, the actuator is the most effective 5 to 10 upstream of the baseline separation point.

  17. The Role of Bluff-Body Roughness Elements on Turbulent Evaporative Fluxes from Porous Surfaces: Momentum and Energy Partitioning

    NASA Astrophysics Data System (ADS)

    Or, D.; Haghighi, E.; Lagela, S.; Aminzadeh, M.

    2014-12-01

    Bluff body obstacles in turbulent flows are common in many natural and engineering applications (from desert pavement and boulders to shrubs). The deceivingly simple geometry of a surface-mounted obstacle in a boundary layer induces a complex and unsteady flow field that affect the surface drag partitioning and transport of scalars form surrounding evaporating surfaces. The readily observable spatio-temporal distribution of localized evaporation rates from infrared measured thermal signatures provide the impetus for a simple zonation scheme that enables estimates of evaporative fluxes around an obstacle. Results from evaporation experiments from sand surfaces with isolated cylindrical elements (bluff bodies) subjected to constant turbulent airflows were in good agreement with model predictions for localized exchange rates. The results show consistent enhancement of evaporating fluxes relative to a smooth surface to formation of vortices that induce thinner boundary layers. We also considered effects of obstacles on (solar) short wave radiation and energy partitioning over surfaces and successfully represented zonation of surface exchange due to momentum (drag partitioning) and variable surface energy balance on localized evaporation. A scheme for upscaling the results to evaporation from surfaces with multiple obstacles will be presented.

  18. PIV measurement of flow around an irregularly rotating disk with bluff bodies

    NASA Astrophysics Data System (ADS)

    Im, Sunghyuk; Jeon, Young Jin; Sung, Hyung Jin

    2011-11-01

    Flow structure interaction between a rotating disk with bluff bodies and surrounding flow has been evaluated by using a tomographic PIV. To examine the dynamics of disks and the fluid flow simultaneously, fluorescence tracer particles and long pass filters were used. Particles and a marked surface pattern were separated by an image processing. The geometries of the bluff bodies and the disk were then obtained by analyzing the marked pattern. Subsequently, a particle volume was reconstructed by MLOS-SMART. The particle displacement was then calculated by the PIV algorithm from the reconstructed particle volume. Rotating disk dynamics and fluid flow were discussed with variety of bluff body shapes and arrangements. Furthermore, the influence of bluff bodies on the flow field was also considered. This study was supported by the Creative Research Initiatives of NRF/MEST (No. 2011-0000423) of Korea.

  19. Processes of coastal bluff erosion in weakly lithified sands, Pacifica, California, USA

    NASA Astrophysics Data System (ADS)

    Collins, Brian D.; Sitar, Nicholas

    2008-05-01

    Coastal bluff erosion and landsliding are currently the major geomorphic processes sculpting much of the marine terrace dominated coastline of northern California. In this study, we identify the spatial and temporal processes responsible for erosion and landsliding in an area of weakly lithified sand coastal bluffs located south of San Francisco, California. Using the results of a five year observational study consisting of site visits, terrestrial lidar scanning, and development of empirical failure indices, we identify the lithologic and process controls that determine the failure mechanism and mode for coastal bluff retreat in this region and present concise descriptions of each process. Bluffs composed of weakly cemented sands (unconfined compressive strength UCS between 5 and 30 kPa) fail principally due to oversteepening by wave action with maximum slope inclinations on the order of 65 at incipient failure. Periods of significant wave action were identified on the basis of an empirical wave run-up equation, predicting failure when wave run-up exceeds the seasonal average value and the bluff toe elevation. The empirical relationship was verified through recorded observations of failures. Bluffs composed of moderately cemented sands (UCS up to 400 kPa) fail due to precipitation-induced groundwater seepage, which leads to tensile strength reduction and fracture. An empirical rainfall threshold was also developed to predict failure on the basis of a 48-hour cumulative precipitation index but was found to be dependent on a time delay in groundwater seepage in some cases.

  20. Bluff evolution and long-term recession rates, southwestern Lake Michigan

    NASA Astrophysics Data System (ADS)

    Rovey, C. W.; Borucki, M. K.

    1994-06-01

    Where eroding cohesive sediments are present, Lake Michigan bluffs range up to 40 m in height, exposing multiple glacial stratigraphic units. Following the model presented here, bluffs form as a wave-cut terrace erodes inland from a point near the original shoreline. The erosion plane is nearly horizontal, in contrast with the eastward dip of the glacial units inherited from underlying bedrock. Therefore, terraces eroding inland produce progressively higher bluffs and expose successively older units at the toe and beneath the lake. This process was repeated several times as lake levels sequentially dropped to their modern stage. The initial modern shoreline, and hence the width of the wave-cut terrace, was determined from four offshore seismic and bottom-sampling profiles. It was picked as an inflection point in the lake bed, occurring offshore of dipping reflectors intersecting the lake bottom. The calculated average recession rate over a 2500-year duration of the modern stage is 1.5 m/yr in contrast to average rates of approximately 0.6 m/yr measured over the last century. Thus rates decrease through time as the terrace widens and wave energy is dampened. By correlating bluff height to recession distance, a third rate of approximately 2.7 m/yr for the first 940 years of recession is calculated from relict Nipissing bluffs. The three rates define a steeply decaying exponential curve in early stages of bluff retreat, flattening into a nearly linear function after 1000 years.

  1. Apparatus And Method For Reducing Drag Of A Bluff Body In Ground Effect Using Counter-Rotating Vortex Pairs

    DOEpatents

    Ortega, Jason M. (Pacifica, CA); Sabari, Kambiz (Livermore, CA)

    2005-12-27

    An aerodynamic base drag reduction apparatus and method for bluff bodies, such as tractor-trailer trucks, utilizing a pair of lift surfaces extending to lift surface tips and located alongside the bluff body such as on opposing left and right side surfaces. In a flowstream substantially parallel to the longitudinal centerline of the bluff body, the pair of lift surfaces generate a pair of counter-rotating trailing vortices which confluence together in the wake of the bluff body in a direction orthogonal to the flowstream. The confluence draws or otherwise turns the flowstream, such as the flowstream passing over a top surface of the bluff body, in and around behind a trailing end of the bluff body to raise the pressure on a base surface at the trailing end and thereby reduce the aerodynamic base drag.

  2. Apparatus And Method For Reducing Drag Of A Bluff Body In Ground Effect Using Counter-Rotating Vortex Pairs

    DOEpatents

    Ortega, Jason M. (Pacifica, CA); Salari, Kambiz (Livermore, CA)

    2005-08-09

    An aerodynamic base drag reduction apparatus and method for bluff bodies, such as tractor-trailer trucks, utilizing a pair of lift surfaces extending to lift surface tips and located alongside the bluff body such as on opposing left and right side surfaces. In a flowstream substantially parallel to the longitudinal centerline of the bluff body, the pair of lift surfaces generate a pair of counter-rotating trailing vortices which confluence together in the wake of the bluff body in a direction orthogonal to the flowstream. The confluence draws or otherwise turns the flowstream, such as the flowstream passing over a top surface of the bluff body, in and around behind a trailing end of the bluff body to raise the pressure on a base surface at the trailing end and thereby reduce the aerodynamic base drag.

  3. Spark ignition of turbulent nonpremixed bluff-body flames

    SciTech Connect

    Ahmed, S.F.; Marchione, T.; Mastorakos, E.; Balachandran, R.

    2007-10-15

    Spark ignition of turbulent nonpremixed bluff-body flames with radial fuel injection for different fuel and air bulk velocities and swirl conditions has been investigated in terms of stability and ignitability limits and ignition probability (P{sub ign}, defined as the probability of igniting the whole flame from a localized 2-mm spark). The velocity field and the mixture fraction distributions have been measured with laser Doppler velocimetry and planar laser-induced fluorescence (PLIF) of acetone, respectively. Successful and failed ignition events have been visualized by high-speed and OH PLIF imaging. The results show that the stability limits are much wider than the ignitability limits, but with swirl, they become closer. The mixture fraction distribution shows high sensitivity to any change in the fuel and air velocities, with the mixture inside the central recirculation zone (CRZ) tending to be relatively well-mixed and rich. Visualization of different spark realizations shows that successful ignition events manage to initiate a flame at the separation corner of the bluff body and that the direction of initial flame propagation depends more on the ignition location than on the flow conditions due to the convection of the flame kernel by the mean flow. With successful spark events inside the CRZ the flame expands in all directions, up to a certain point, when it starts forming the shape of the stable flame. The highest P{sub ign} was close to the CRZ boundaries with low P{sub ign} or no ignition inside CRZ when the mixture there was rich. Under conditions where the CRZ is not close to the rich flammability limit, P{sub ign} is substantial. Downstream of the CRZ, P{sub ign} is uniform but low due to the adverse velocity. The probability of just initiating a kernel is higher than P{sub ign}, especially, in the area above the CRZ. With swirl, the highest P{sub ign} is at the burner exit, with no ignition inside the CRZ because the mixture is too lean. The data highlight the difference between P{sub ign} and the probability of kernel initiation and the flammability factor F (the probability of finding a mixture within the nominal flammability limits) and emphasize that flame propagation in inhomogeneous mixtures must be captured by any model that aims to simulate ignition of nonpremixed flame burners. (author)

  4. a Hybrid Vortex Method for Flows Over a Bluff Body

    NASA Astrophysics Data System (ADS)

    Cheng, M.; Chew, Y. T.; Luo, S. C.

    1997-02-01

    A hybrid vortex method was developed to simulate the two-dimensional viscous incompressible flows over a bluff body numerically. It is based on a combination of the diffusion-vortex method and the vortex-in-cell method by dividing the flow field into two regions. In the region near the body surface the diffusion-vortex method is used to solve the Navier-Stokes equations, while the vortex-in-cell method is used in the exterior domain. Comparison with results obtained by the finite difference method, other vortex methods and experiments shows that the present method is well adapted to calculate two-dimensional external flows at high Reynolds number. It is capable of calculating not only the global characteristics of the separated flow but also the evolution of the fine structure of the flow field with time precisely. The influence of the grid system and region decomposition on the results will also be discussed. by 1997 John Wiley & Sons, Ltd.

  5. White Bluffs Pickling Acid Cribs expedited response action proposal

    SciTech Connect

    Not Available

    1993-07-01

    The US Environmental Protection Agency (EPA) and Washington State Department of Ecology (Ecology) recommended in a letter dated March 4, 1992 (Attachment 1) that the US Department of Energy (DOE) prepare an expedited response action (ERA) for the White Bluffs Pickling Acid Cribs Site. The lead regulatory agency for this ERA is the EPA, with Ecology providing support. The goal of this ERA is to reduce the potential of any residual contaminant migration from the cribs to the soil column and groundwater. The cribs are the only waste site within the 100-IU-5 operable unit. Since the operable unit is surrounded by other waste units, tracing the potential groundwater contamination from the 100-IU-5 operable unit for this ERA would not be effective. Groundwater will be investigated with the 100-IU-2 operable unit. This ERA proposal presents the characterization data from the site investigations conducted in November of 1992. This information is evaluated to present the best method for reducing potential of contaminant migration from the disposal unit, ensuring both protection of human health and the environment. The ERA proposal will undergo a public review. EPA and Ecology will issue an Action Agreement Memorandum after comment resolution. This Action Memorandum may authorize implementation of the ERA proposal`s recommended alternative. The ERA may also provide a No Further Action Interim Record of Decision (IROD) of the 100-IU-5 operable unit.

  6. Short-Term Bluff Recession Behavior Along Pennsylvania's Great Lakes Coastline, USA

    NASA Astrophysics Data System (ADS)

    Foyle, A. M.; Naber, M. D.; Pluta, M. J.

    2011-12-01

    Coastal bluff retreat is a common problem along the world's unconsolidated coastlines. On the Great Lakes coast of Pennsylvania, Quaternary clay-rich glacial till, paleo-lake plain, and sandy strandplain sequences overlie Devonian bedrock. These Quaternary strata are subject to subaerial and lacustrine erosional processes that cause permanent coastal land loss at spatially variable rates, with the former (runoff, slumping, groundwater focusing, etc) dominating over the latter (wave and current scour, abrasion, etc). Land loss is of concern to environmental agencies because land-use planning should account for spatial and temporal variability in land-loss rates, and because bluff erosion contributes to a temporary degradation in coastal water quality. The goal of this study is to evaluate spatial variability in bluff retreat rates along a 20 km sector of Pennsylvania's short Great Lakes coast. High resolution LiDAR data covering a one-decade time frame (1998-2007) permit bluff-crest mapping on two comparable data sets that captures change within a timeframe similar to CZM planning intervals. Short-term recession data can be more useful, cost-effective, and accurate than long-term analyses that use lower-resolution field measurements, T-sheets, and historical aerial photography. Bluffs along the 20 km coastal study site consist of up to 26 m of unlithified Quaternary sediments overlying a 1-4 m ledge of sub-horizontal Devonian shale and sandstone. Bluff slopes range from 20-90 degrees, beaches are narrow (<8 m wide) or absent, and the bluffs are seasonally shielded by ground-freeze and lake ice. DEMs, hillshades, and slope and contour maps were generated from bare-earth 1998 and 2007 LiDAR data, and checked against 2005 aerial ortho-photography. Maps were analyzed at a scale of 1:120 in ArcGIS and the bluff crest was identified primarily by the visual-break-in-slope method. Rates of bluff retreat derived using DSAS vary from unresolvable to as much as 2.2 m/yr, averaging less than 0.3 m/yr which is consistent with known long-term rates. Very-short term rates of recession can locally exceed 11 m/yr. In general, bluffs retreat relatively linearly where poorly-vegetated glacial till dominates the bluff stratigraphy, while along higher-elevation strandplain-capped bluff sections, rotational earth slumps (<100 m diameter) are well developed. Retreat rates are highest at slump areas and at 1st - 2nd order ravines (100-300 m in length). Both of these settings are associated with focused groundwater discharge from thin lake plain and strandplain aquifers in particular. Other factors do influence bluff retreat temporally, but are not important at the scale of this study.

  7. 33 CFR 207.169 - Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207.169 Section 207.169 Navigation... REGULATIONS § 207.169 Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration,...

  8. Real-time monitoring of bluff stability at Woodway, Washington, USA

    USGS Publications Warehouse

    Baum, R.L.; Harp, E.L.; Likos, W.J.; Powers, P.S.; LaHusen, R.G.

    1998-01-01

    On January 15, 1997, a landslide of approximately 100,000-m3 from a coastal bluff swept five cars of a freight train into Puget Sound at Woodway, Washington, USA, 25 km north of downtown Seattle. The landslide resulted from failure of a sequence of dense sands and hard silts of glacial and non-glacial origin, including the Lawton Clay, a hard, jointed clayey silt that rarely fails in natural slopes. Joints controlled ground-water seepage through the silt and break-up of the landslide mass. During September of 1997, the US Geological Survey began measuring rainfall, ground-water pressures, and slope movement at the bluff where the landslide occurred. Data are collected every 15 minutes and updated hourly on the World-Wide-Web. Pore pressures observed from September 1997 to February 1998 generally were low and pressures near the bluff face, in the upper few meters of the hard clayey silt, increased gradually.

  9. Symmetry breaking of rigid/flexible plates in bluff body wakes generates rotation and drift

    NASA Astrophysics Data System (ADS)

    Brosse, Nicolas; Lacis, Ugis; Lundell, Fredrik; Bagheri, Shervin; Ingremeau, Francois; Kellay, Hamid; Mazzino, Andrea

    2013-11-01

    Bluff body wakes have historically been important for understanding nature and aiding industry. For Reynolds numbers above approximately Re ~ 10 , a recirculation bubble develops behind the bluff body. If a solid or elastic appendage is attached to the bluff body, it may exert a torque and a side force on the body. We use theory, numerical simulations and experiments to investigate and explain this phenomenon. More specifically, numerical simulations are carried out for a freely falling cylinder with an attached splitter plate for Re ~ 50 . Experiments of a fixed cylinder with an attached elastic filament are preformed using a vertical soap-film tunnel for Re ~ 2000 . Both experiments and simulations reveal that if a body has an appendage smaller than or of the same order as the body it is attached to, the body rotates and drifts. We explain our findings with a simple model and discuss the implications for propulsion.

  10. Alteration of volcaniclastic deposits at Minna Bluff: Geochemical insights on mineralizing environment and climate during the Late Miocene in Antarctica

    NASA Astrophysics Data System (ADS)

    Antibus, Joanne V.; Panter, Kurt S.; Wilch, Thomas I.; Dunbar, Nelia; McIntosh, William; Tripati, Aradhna; Bindeman, Ilya; Blusztajn, Jerzy

    2014-08-01

    minerals in volcaniclastic deposits at Minna Bluff, a 45 km long peninsula in the Ross Sea, are used to infer processes of alteration and environmental conditions in the Late Miocene. Glassy volcaniclastic deposits are altered and contain phillipsite and chabazite, low to high-Mg carbonates, chalcedony, and clay. The ?18O of carbonates and chalcedony is variable, ranging from -0.50 to 21.53 and 0.68 to 10.37, respectively, and ?D for chalcedony is light (-187.8 to -220.6), corresponding to Antarctic meteoric water. A mean carbonate 87Sr/86Sr ratio of 0.70327 0.0009 (1?, n = 12) is comparable to lava and suggests freshwater, as opposed to seawater, caused the alteration. Minerals were precipitated at elevated temperatures (91 and 104C) based on quartz-calcite equilibrium, carbonate 13C-18C thermometry (?47 derived temperature = 5 to 43C) and stability of zeolites in geothermal systems (>10 to 100C). The alteration was a result of isolated, ephemeral events involving the exchange between heated meteoric water and glass during or soon after the formation of each deposit. Near-surface evaporative distillation can explain 18O-enriched compositions for some Mg-rich carbonates and chalcedony. The ?18Owater calculated for carbonates (-15.8 to -22.9) reveals a broad change, becoming heavier between 12 and 7 Ma, consistent with a warming climate. These findings are independently corroborated by the interpretation of Late Miocene sedimentary sequences recovered from nearby sediment cores. However, in contrast to a cold-based thermal regime proposed for ice flow at core sites, wet-based conditions prevailed at Minna Bluff; a likely consequence of high heat flow associated with an active magma system.

  11. Twin solution calorimeter determines heats of formation of alloys at high temperatures

    NASA Technical Reports Server (NTRS)

    Darby, J. B., Jr.; Kleb, R.; Kleppa, O. J.

    1968-01-01

    Calvert-type, twin liquid metal solution calorimeter determines the heats of formation of transition metal alloys at high temperatures. The twin differential calorimeter measures the small heat effects generated over extended periods of time, has maximum operating temperature of 1073 degrees K and an automatic data recording system.

  12. Experiments to investigate direct containment heating phenomena with scaled models of the Calvert Cliffs Nuclear Power Plant

    SciTech Connect

    Blanchat, T.K.; Pilch, M.M.; Allen, M.D.

    1997-02-01

    The Surtsey Test Facility is used to perform scaled experiments simulating High Pressure Melt Ejection accidents in a nuclear power plant (NPP). The experiments investigate the effects of direct containment heating (DCH) on the containment load. The results from Zion and Surry experiments can be extrapolated to other Westinghouse plants, but predicted containment loads cannot be generalized to all Combustion Engineering (CE) plants. Five CE plants have melt dispersal flow paths which circumvent the main mitigation of containment compartmentalization in most Westinghouse PWRs. Calvert Cliff-like plant geometries and the impact of codispersed water were addressed as part of the DCH issue resolution. Integral effects tests were performed with a scale model of the Calvert Cliffs NPP inside the Surtsey test vessel. The experiments investigated the effects of codispersal of water, steam, and molten core stimulant materials on DCH loads under prototypic accident conditions and plant configurations. The results indicated that large amounts of coejected water reduced the DCH load by a small amount. Large amounts of debris were dispersed from the cavity to the upper dome (via the annular gap). 22 refs., 84 figs., 30 tabs.

  13. Calvert Cliffs Nuclear Power Plant Life Cycle Management/License Renewal Program: System, structure, and component screening. Final report

    SciTech Connect

    Doroshuk, B.W.; Tilden, B.M.; Hostetler, D.R.; Klein, D.J.; Negin, C.A.

    1994-09-01

    Central to the Life Cycle Management (LCM) Program for the Calvert Cliffs Nuclear Plant is its Integrated Plant Assessment (IPA) process; a comprehensive, systematic evaluation of the effectiveness of age-related degradation management for the plant`s important systems, structures, and components. The first step in this process is the screening of functionally important systems, structures that warrant further evaluation of aging issues. A detailed method and procedures for conducting this screening have been developed and thoroughly tested. The development and application of these procedures at Calvert Cliffs should permit other utilities to avoid implementation problems and avoid substantial front-end development costs. The IPA process is initiated by a screening step that identifies important systems, structures, and components for further evaluation. This report contains the screening methodology, provides procedures for System Level Screening and Component Level Screening, and summarizes results for five systems that represent a wide range of use. These are the Reactor Coolant System, Compressed Air System, Saltwater Cooling System, Electrical 4 Kv Transformers and Buses, and the Reactor Protective System. Examples of component screening are included for the Reactor Coolant System. These screening results show how to determine which equipment`s maintenance programs should be checked for degradation management effectiveness.

  14. 78 FR 20942 - Niobrara Confluence and Ponca Bluffs Conservation Areas, NE and SD; Draft Environmental Impact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ...We, U.S. Fish and Wildlife Service (FWS) and the National Park Service (NPS), as lead agencies, announce the availability of a draft environmental impact statement (DEIS) and land protection plan (LPP) for the proposed Niobrara Confluence Conservation Area and Ponca Bluffs Conservation Area in Nebraska and South Dakota for public review and comment. In these documents, we describe......

  15. 75 FR 65230 - Drawbridge Operation Regulation; Arkansas Waterway, Pine Bluff, AR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    ...) entitled Drawbridge Operation Regulation; Arkansas Waterway, Pine Bluff, AR in the Federal Register (75 FR... has a substantial direct effect on State or local governments and would either preempt State law or... effect on one or more Indian tribes, on the relationship between the Federal Government and Indian...

  16. 33 CFR 207.170 - Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Bluff, Fla.; pool level. 207.170 Section 207.170 Navigation and Navigable Waters CORPS OF ENGINEERS... above sea level at such times as may be authorized in writing by the District Engineer, Jacksonville... Engineer, an emergency exists requiring the lowering of the pool level to an elevation less than 56.5...

  17. Maastrichtian ammonites chiefly from the Prairie Bluff Chalk in Alabama and Mississippi

    USGS Publications Warehouse

    Cobban, W.A.; Kennedy, W.J.

    1995-01-01

    The Prairie Bluff Chalk of Alabama and Mississippi yields a diverse ammonite fauna of Maastrichtian age. Twenty-eight species, of which three are new, are recorded. The bulk of the fauna can be referred to a Discoscaphites conradi assemblage zone, but some elements in the fauna are significantly older. -Authors

  18. Flow structure and combustion in nonpremixed turbulent bluff-body stabilized flames

    SciTech Connect

    Namazian, M.; Kelly, J.; Schefer, R.W; Johnston, S.C.

    1986-04-01

    The flow structures and combustion characteristics of bluff-body stabilized flames were studied using planar flow visualization and direct flame photography. In the planar flow visualization the fuel was seeded with alumina particles and a thin sheet of laser light was used to illuminate the field of view. Mie scattering from the particles in the illuminated plane was then recorded on photographic film. For fixed fuel velocity and low air velocity the particle streak photographs showed a three-dimensional vortical flow structure near the burner face that acted to stabilize the flame at the bluff-body face. For high air velocity, the vortical structures were not observed and the flames were detached. In this case, the fuel jet stagnates on the axis, which stabilizes the flame away from the burner face. Short-exposure Mie scattering images were used to provide detailed information about the turbulent structures that occur in bluff-body flames. These structures can be large, irregular and time varying. It is concluded that instantaneous planar imaging diagnostic techniques are very useful for the characterization of these flames. The experimental results obtained in this study are anticipated to provide new insight into the combustion characteristics of bluff-body flames, insight that should prove useful in developing the next generation of computer models describing such flames. 8 refs., 6 figs., 4 tabs.

  19. Reinvestigation of the Bee Bluff Structure South of Uvalde, Texas, `The Uvalde Crater.'

    NASA Astrophysics Data System (ADS)

    Graham, R. A.; Wilson, W. F.

    2005-03-01

    Investigation of the Bee Bluff Structure provides new evidence for an impact crater origin. A 300 kg rock preserving numerous impactite features called the 'Uvalde Crater Rosetta Stone,' promises to provide detail on the first billion nanoseconds of the impact events.

  20. Acoustic wave excitation during the aerodynamic interaction between a fan blade and a bluff obstacle

    NASA Astrophysics Data System (ADS)

    Chukhlantsev, S. G.

    1990-08-01

    The forces generated by flow over the surface of a fan blade and a bluff obstacle are calculated using the discrete vortex method. The results are then used to determine the sound source and the acoustic field formed. Results of an experimental verification of the analytical relations are presented.

  1. Investigations of air flow behavior past a conical bluff body using particle imaging velocimetry

    NASA Astrophysics Data System (ADS)

    Dutka, Marcin; Ditaranto, Mario; Lvs, Terese

    2015-11-01

    An annular jet flow past conical bluff body in an original configuration was investigated using particle imaging velocimetry for Reynolds ( Re) numbers between 4900 and 58,800. The studied geometrical configuration finds its application in a novel low NO x burner; therefore, the flow conditions corresponding to burner operation were investigated in detail. It was found that the flow is laminar at Re = 4900 and the transition from a laminar to a turbulent flow regime starts at Re = 9800-14,700. The length of the recirculation zone increases abruptly when the flow becomes turbulent and is independent of the Re number within the turbulent flow regime. The fraction of the total flow rate representing flow circulating in the recirculation zone is relatively constant for the investigated flows. An increase in main stream velocity implies proportional decrease in the residence time in the recirculation zone observed within the turbulent flow regime. Two types of coherent structures shed from the trailing edge of the bluff body are identified using proper orthogonal decomposition technique. The first is vortices that cross the centerline of the bluff body and travel downstream along the centerline. The second is smaller vortex structures that are shed alternately from the trailing edge of the bluff body.

  2. Sedimentological indicators of paleoenvironments and siliciclastic stratigraphic sequences in some Miocene deposits of the Calvert Cliffs, southern Maryland

    USGS Publications Warehouse

    Shideler, G.L.

    1994-01-01

    Middle Miocene siliciclastic deposits comprising the Calvert Cliffs section at the Baltimore Gas and Electric Company's (BG&E) nuclear power plant site in southern Maryland were analyzed in terms of lithostratigraphy, sedimentary structures, and granulometric parameters, to interprete paleo-environments within a sequence-stratigraphic framework. In terms of sequence-stratigraphic models, the BG&E section can be interpreted as consisting of two genetic stratigraphic sequences (Galloway model), namely, a shelf sequence and an overlying deltaic sequence. Using the Exxon model, the section consists of two third-order (1-5 m.y. duration) depositional sequences. The stratigraphic sequences of the BG&E section reflect both relatively short-term eustatic transgressive events, as well as a long-term regressive trend with associated local deltation and coastal progradation. The regression probably signified a regional basinward shift of depocenters within the Salisbury embayment during Miocene time. -from Author

  3. Environmental radionuclide concentrations in the vicinity of the calvert cliffs nuclear power plant: 1985-1986. Final report

    SciTech Connect

    Domotor, S.L.; McLean, R.I.

    1988-11-01

    High-resolution gamma spectroscopy was used to determine radionuclide concentrations in sediment, finfish, shellfish, and aquatic vegetation collected from the Chesapeake Bay in the vicinity of the Calvert Cliffs Nuclear Power Plant (CCNPP) during 1985-1986. Low concentrations of radionuclides attributable to CCNPP (Ag-110m, Co-58, Co-60, and Zn-65) were detected in all biota (except edible finfish) and in sediments. Silver-110m was the principal CCNPP-related radionuclide detected in biota (particularly oysters); Co-58 and Co-60 were the principal CCNPP-related radionuclides detected in sediments. CCNPP-related radionuclide concentrations detected in Bay biota and sediments were within ranges observed in previous years and represent small increments to radionuclide concentrations in the Bay relative to natural and weapons test levels.

  4. Bluff body fluid dynamics of a D-section with moving surface boundary-layer control

    SciTech Connect

    Munshi, S.R.; Modi, V.J.; Yokomizo, Toshio

    1995-12-01

    Wind effects on bluff structures include higher drag force, vortex resonance and galloping type instabilities. Vibrations of tall buildings, bridges, smokestacks etc. have been of interest to scientists and engineers. Recent advances in material science and structural design have led to structures with reduced stiffness making them prone to wind, earthquake, as well as ocean waves and current excited oscillations. The present paper addresses this issue fundamentally through a comprehensive study aimed at the Moving Surface Boundary-layer Control (MSBC) of the classical D-section type bluff geometry which is susceptible to both vortex resonance and galloping type of instabilities. Extensive wind tunnel, numerical and flow visualization studies suggest that the concept of the MSBC represents a versatile tool for drag reduction and vibration control of the D-section.

  5. Large eddy simulation of flows around ground vehicles and other bluff bodies.

    PubMed

    Krajnovic, Sinisa

    2009-07-28

    A brief review of large eddy simulation (LES) applications for different bluff-body flows performed by the author and his co-workers is presented. Examples of flows range from simple cube flows characterized by sharp edge separation over a three-dimensional hill where LES relies on good near-wall resolution, to complex flows of a tall, finite cylinder that contains several flow regimes that cause different challenges to LES. The second part of the paper is devoted to flows around ground vehicles at moderate Reynolds numbers. Although the present review proves the applicability of LES for various bluff-body flows, an increase of the Reynolds number towards the operational speeds of ground vehicles requires accurate near-wall modelling for a successful LES. PMID:19531512

  6. Orientation of bluff body for designing efficient energy harvesters from vortex-induced vibrations

    NASA Astrophysics Data System (ADS)

    Dai, H. L.; Abdelkefi, A.; Yang, Y.; Wang, L.

    2016-02-01

    The characteristics and performances of four distinct vortex-induced vibrations (VIVs) piezoelectric energy harvesters are experimentally investigated and compared. The difference between these VIV energy harvesters is the installation of the cylindrical bluff body at the tip of cantilever beam with different orientations (bottom, top, horizontal, and vertical). Experiments show that the synchronization regions of the bottom, top, and horizontal configurations are almost the same at low wind speeds (around 1.5 m/s). The vertical configuration has the highest wind speed for synchronization (around 3.5 m/s) with the largest harvested power, which is explained by its highest natural frequency and the smallest coupled damping. The results lead to the conclusion that to design efficient VIV energy harvesters, the bluff body should be aligned with the beam for low wind speeds (<2 m/s) and perpendicular to the beam at high wind speeds (>2 m/s).

  7. Aerodynamic drag reduction apparatus for gap-divided bluff bodies such as tractor-trailers

    DOEpatents

    Ortega, Jason M. (Pacifica, CA); Salari, Kambiz (Livermore, CA)

    2006-07-11

    An apparatus for reducing the aerodynamic drag of a bluff-bodied vehicle such as a tractor-trailer in a flowstream, the bluff-bodied vehicle of a type having a leading portion, a trailing portion connected to the leading portion, and a gap between the leading and trailing portions defining a recirculation zone. The apparatus is preferably a baffle assembly, such as a vertical panel, adapted to span a width of the gap between the leading and trailing portions so as to impede cross-flow through the gap, with the span of the baffle assembly automatically adjusting for variations in the gap width when the leading and trailing portions pivot relative to each other.

  8. Calvert Cliffs Nuclear Power Plant Life Cycle Management/License Renewal Program: Containment system component evaluation and program evaluation. Final report

    SciTech Connect

    Doroshuk, B.W.; Tilden, B.M.; Tucker, R.L.; Hostetler, D.R.; Tai, T.

    1995-03-01

    Central to the Life Cycle Management (LCM) Program for the Calvert Cliffs Nuclear Power Plant (CCNPP) plant is its Integrated Plant Assessment (IPA) process. The IPA is a comprehensive, systematic evaluation of the effectiveness of age-related degradation management for the plant`s important systems, structures, and components. Components of structures identified as functionally important and within the scope of license renewal in the screening step are evaluated to determine if they are subject to aging management review. For those that are, further evaluations of aging issues are performed. At Calvert Cliffs, a detailed method and procedures for conducting component evaluations of structures have been developed and thoroughly tested. The development and application of these procedures have resolved problems that other utilities can avoid by adapting these methods to their own plants. The first report of this series contains an overview of the LCM and IPA process. This report, which is another in the series of EPRI reports on the Calvert Cliffs IPA process, describes the methodology for performing component and program evaluations for structures.

  9. A localized corrosion assessment of 6% molybdenum stainless steel condenser tubing at the Calvert Cliffs Nuclear Power Plant

    SciTech Connect

    Klein, P.A.; Krause, C.D.; Friant, C.L.; Kain, R.M.

    1994-12-31

    A condition assessment was performed on the Calvert Cliffs Nuclear Power Plant Unit 1 Main Steam Condenser 6% molybdenum stainless steel tubing. This work consisted of eddy current (EC) examination, in-situ visual examination of tubes, and destructive analysis of pulled tubes. The assessment objectives were as follows: to determine the tubing degradation mechanism, to render the condenser leak-tight, to identify methods of improving condenser life management, and to develop a basis for projecting the remaining condenser life. Once the corrosion mechanism was identified, seawater corrosion tests were performed on UNS N08366 and N08367 tubing using vinyl sleeves, Type 316 stainless compression fittings, and epoxy paint as crevice formers. Based on eddy current examination results, greater than 95% of the 49,500 tubes in the condenser had no detectable degradation. Over 1,200 tubes were plugged with either eddy current indications measuring greater than 60% wall loss or with obstructions. One waterbox (11A) contained 52% of all eddy current indications with over half of these in one section (B). Destructive analysis of pulled tubes revealed crevice corrosion, a form of localized corrosion that initiated under deposits. This type of corrosion occurred most often and had the deepest penetration in the weld seam. This was attributed to molybdenum and chromium segregation in the as-welded tubes and to deleterious secondary phases formed during weld solidification.

  10. Review of thermal-hydraulic calculations for Calvert Cliffs and H. B. Robinson PTS study. [Pressurized thermal shock

    SciTech Connect

    Jo, J.H.; Yuelys-Miksis, C.; Rohatgi, U.S.

    1984-01-01

    Thermal-hydraulic transient calculations performed by LANL using the TRAC-PF1 code and by INEL using the RELAP5 code for the USNRC pressurized thermal shock (PTS) study of the Calvert Cliffs and H.B. Robinson Nuclear Power Plants have been reviewed at BNL including the input decks and steady state calculations. Furthermore, six transients for each plant have been selected for the in-depth review. Simple hand calculations based on the mass and energy balances of the entire reactor system, have been performed to predict the temperature and pressure of the reactor system, and the results have been compared with those obtained by the code calculation. In general, the temperatures and pressures of the primary system calculated by the codes have been very reasonable. The secondary pressures calculated by TRAC appear to indicate that the codes have some difficulty with the condensation model and further work is needed to assess the code calculation of the U-tube steam generator pressure when the cold auxiliary feedwater is introduced to the steam generator. However, it is not expected that this uncertainty would affect the transient calculations significantly.

  11. A RETRAN model of the Calvert Cliffs-1 pressurized water reactor for assessing the safety implications of control systems

    SciTech Connect

    Renier, J P.A.; Smith, O L

    1987-03-01

    The failure mode and effects analysis of Calvert Cliffs-1 identified sequences of events judged sufficiently complex to merit further analysis in detailed dynamic simulations. This report describes the RETRAN model developed for this purpose and the results obtained. The mathematical tool was RETRAN2/Mod3, the latest version of a widely used and extensively validated thermal-hydraulics production code obtained by license agreement with the developer, Electric Power Research Institute, and installed on the ORNL BM-3033 computers. RETRAN2 is based on a first-principles methodology that treats two-phase flow with slip. Thermal equilibrium of phases is assumed except in the pressurizer, where non-equilibrium processes are important and special methodology is used. Heat transfer in solids is obtained from the conventional conduction equation. Point or 1-D kinetics is available for the reactor core. The fundamental methodology is supplemented with a broad list of process submodels that calculate heat transfer coefficients, fluid and metal state properties, choked flow, form and wall friction losses, and other parameters. Also supplied are component submodels for various types of valves and pumps, the latter of which incorporate four-quadrant characteristics for components in which two-phase or reverse flow may be expected, and head versus flow curves for others. Extensive input allows the code to be highly particularized to a specific plant. The major investment in time and manpower occurs in setting up the base case; changes are comparatively easy to implement.

  12. Dry-surface coating method for visualization of separation on a bluff body

    NASA Technical Reports Server (NTRS)

    Sadeh, W. Z.; Brauer, H. J.; Durgin, J. R.

    1981-01-01

    A simple and relatively accurate dry-surface coating method for visualization of the flow separation on a circular cylinder (or any bluff body) during wind tunnel tests is described. The technique consists of (1) application of a thin coating composed of an indicator and a paint carrier; (2) drying of the film; (3) conditioning of the coating with an acidic solution to ensure a suitable color reaction; (4) release into the body wake of a gas able to produce a base through chemical reaction with the solvent of the conditioning solution; and (5) color reaction according to pH.

  13. 230. CCC Camp NP21 was established at the Bluffs (Doughton ...

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

    230. CCC Camp NP-21 was established at the Bluffs (Doughton Park) located on what is now the Doughton Park Maintenance Area. It opened September 1, 1938 and was abandoned July 17, 1942. Crews were assigned to the first landscape development on the parkway in the Cumberland Knob Area. This work entailed removal of debris and downed wood, slope flattening and rounding, seeding shoulders and planting along the road, and improvement of fields and forest to the side of the roadway. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  14. A vortex panel analysis of circular-arc bluff-bodies in unsteady flow

    SciTech Connect

    Strickland, J.H.

    1989-01-01

    A method which is capable of calculating the unsteady flow field around circular-arc bluff bodies of zero thickness is presented. This method utilizes linear vortex panels to model the body surface and a portion of the wake surfaces. Discrete vortices are used to model the remainder of the wake surfaces. Separation is assumed to occur at the sharp edges of the bodies. Numerical results for circular-arc bodies with included angles of less than 180/degree/ are compared with experimental data and found to be in good agreement. 31 refs., 15 figs.

  15. On vortex structures and processes over bluff bodies in impulsive flow

    NASA Astrophysics Data System (ADS)

    Finaish, F.

    1991-07-01

    An experimental system that generates and visualizes unsteady motions in air was employed to visualize vortex developments over bluff bodies in impulsive started flow. The study presents photographic sequences of impulsive flow over circular and square cyliners for a flow-Reynolds number of 200. A comparison of physical and numerical visualization for impulsive flow over a flat plate at a 50-degree angle of attack and for a flow-Reynolds number of 1000 is also presented. The visualization examples reveal the details of vortex separation and subsequent devlopments and may be utilized as a reference to guide and economize computer visualization efforts on unsteady separated flows.

  16. Reduction of Aerodynamic Noise Generated by a Bluff-Shaped Pantograph Head Using Synthetic Jet Actuators

    NASA Astrophysics Data System (ADS)

    Kishige, Hiroaki; Minobe, Takayuki; Ikeda, Mitsuru; Suzuki, Masahiro

    With an increase in the maximum speed of Shinkansen trains, it becomes imperative to resolve aerodynamic and aeroacoustic problems related to pantographs. Hence, some methods based on flow control have been studied to improve the aerodynamic and aeroacoustic characteristics. In this study, the authors attempted to control the flow around a pantograph by using synthetic jets. The results of numerical and experimental tests indicate that the synthetic jets can stabilize the flow around the bluff-shaped pantograph head, thus resulting in a reduction in aerodynamic noise.

  17. Return to Coalsack Bluff and the Permian Triassic boundary in Antarctica

    NASA Astrophysics Data System (ADS)

    Retallack, Gregory J.; Greaver, Tara; Jahren, A. Hope

    2007-01-01

    Coalsack Bluff was the first discovery site in Antarctica for the latest Permian to earliest Triassic reptile Lystrosaurus. This together with discovery of Permian Glossopteris leaves during the heroic age of Antarctic exploration, indicated not only that Antarctica was part of Gondwanaland, but also that Antarctic rocks recorded faunas from the greatest of all mass extinctions at the Permian-Triassic boundary. Pinpointing the exact stratigraphic level of this life crisis has recently become possible using δ 13C values in terrestrial organic matter. Multiple, short-lived events of 13C depletion may reflect carbon cycle crises, with the isotopic change a measure of terrestrial and atmospheric disequilibrium. Additional evidence for ecosystem reorganization came from changes in paleosol types and their root traces. Such studies previously completed at the Antarctic localities of Graphite Peak, Mount Crean, Portal Mountain, Shapeless Mountain and Allan Hills, are here extended to Coalsack Bluff. Carbon isotopic values in Permian rocks at Coalsack Bluff average - 23.08 ± 0.25‰, but begin to decline within the last coal with leaves ( Glossopteris), roots ( Vertebraria) and permineralized stumps ( Araucarioxylon) of glossopterids. The low point in ä 13C values is - 27.19‰ at 5.6 m above the last coal, which is capped by unusually abundant pyrite, and a claystone breccia with common clasts of redeposited clayey soils. Above this are massive quartz-rich sandstones of braided streams, considered a geomorphic response to deforestation and soil erosion following the mass extinction. Distinctive berthierine-bearing paleosols (Dolores pedotype) within these sandstones have unoxidized iron taken as evidence of severe groundwater hypoxia. Other paleosols at this stratigraphic level are like those in other Early Triassic rocks of Antarctica, which indicate unusually warm and humid conditions for such high paleolatitude lowlands. Waterlogging is also indicated by newly discovered kinds of paleosol (Ernest pedotype) with groundwater calcretes. The lack of peat accumulation in such waterlogged lowlands, berthierine in paleosols and large negative carbon isotopic shift at Coalsack Bluff support the idea of atmospheric pollution with methane from submarine and permafrost clathrates as a cause for the Permian-Triassic mass extinction. Hypoxic soils would have killed lowland plants by preventing root respiration and hypoxic air would have challenged vertebrates with pulmonary edema. Causes for catastrophic methane release remain unclear. Flood basalt eruptions, dolerite intrusions into coal measures, submarine landslides, tectonic faulting, and bolide impact suggested for episodes of methane release at other times are also plausible for the Permian-Triassic boundary.

  18. Flow field behind a fixed bluff body in a vertical pipe simulating a wake of a Taylor bubble

    NASA Astrophysics Data System (ADS)

    Babin, V.; Barnea, D.; Shemer, L.

    2013-10-01

    The hydrodynamic structure of the wake of an axisymmetric bluff body that simulates the shape of a moving elongated (Taylor) bubble in a vertical pipe was studied using Particle Image Velocimetry in laminar and turbulent background flows. The distribution of the mean axial and radial velocity components in the wake, as well as the spatial variation of the normal and shear stresses are presented and compared with the corresponding quantities in the wake of the gas bubble. The accumulated results enable estimates of the spatial variation of turbulent energy production term in the undeveloped separated flow in the wake of the bluff body.

  19. Environmental radionuclide concentrations in the vicinity of the Calvert Cliffs Nuclear Power Plant and the Peach Bottom Atomic Power station: 1995

    SciTech Connect

    Jones, T.S.; Frithsen, J.B.; McLean, R.I.

    1997-02-01

    The Maryland Power Plant Research Program monitors concentrations of natural, weapons, and power plant produced radionuclides in environmental samples collected from the Chesapeake Bay in the vicinity of the Calvert Cliffs Nuclear Power Plant (CCNPP) and from the Susquehanna River-Chesapeake Bay system in the vicinity of Peach Bottom Atomic Power Station (PBAPS). The purpose of this monitoring is to determine the fate, transport, and potential effects of power plant produced radionuclides. Radionuclide concentrations in shellfish, finfish, aquatic vegetation, and sediment were measured using high-resolution gamma spectrometry. Radionuclides in environmental samples originated from natural sources, atmospheric weapons testing, and normal operations of CCNPP and PBAPS.

  20. The use of plasma actuators for bluff body broadband noise control

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhang, Xin; Huang, Xun

    2010-08-01

    Experiments were conducted using plasma actuators to control broadband noise generated by a bluff body flow. The motivation behind the study was to explore the potential of plasma actuators to reduce landing gear noise during approach phase of an aircraft. The control effectiveness of both dielectric barrier discharge and sliding discharge plasma actuators were tested in laboratory environment, using a representative bluff body consisting of a circular cylinder and an oblique strut. Noise measurements were taken in an anechoic chamber using a phased microphone array and far-field microphones. Results showed that the upstream directed plasma forcing, located at 90 deg on the upstream cylinder with respect to the approaching flow, could effectively attenuate the broadband noise radiated from the wake flow interaction with the downstream strut. With the same AC electrical power consumption, the sliding discharge with additional DC voltage was found to be more effective due to its elongated plasma distribution and higher induced flow momentum. Measurements using particle image velocimetry suggested that the flow speed impinging on the downstream strut was reduced by the upstream plasma forcing, contributing to the reduced noise.

  1. The molluscan fauna of the Alum Bluff group of Florida, Part II, Astartacea, Carditacea, Chamacea

    USGS Publications Warehouse

    Gardner, Julia

    1926-01-01

    The first of the series of papers upon the Mollusca of the Alum Bluff group covered the orders of the Prionodesmacea and the Anomalodesmacea. The Mollusca were by the beginning of Miocene time so far advances in development that the great majority are included under the highest of the three orders, the Teleodesmacea, characterized in the adult stages by the differentiation of the hinge teeth into distinct cardinals and laterals. This paper, the second of the series, covers the most primitive of the Teleodesmacea in the Alum Bluff group. All three of the superfamilies considered - the Astartacea, the Carditaeea, and the Chamacea-are included under Dall's group of the Diogenodonta, which is characterized in the normal forms by one or two laterals and not more than three cardinals. The Carditacea are very closely related to the Astartacea in hinge armature but differ in the development of a pronounced radial sculpture. The Chamacea have until recently been considered an offshooting group from the Carditacea that have been greatly modified by their sessile habit. Some doubt has been thrown upon this relationship by the late morphologic studies of Odhner.

  2. Data supporting the screening risk assessment for the Pine Bluff Arsenal Chemical Demilitarization Facility. Final report

    SciTech Connect

    Legg, W.E.

    1995-08-01

    The Pine Bluff Arsenal is a U.S. Army Armament, Munitions, and Chemical Command (AMCCOM) facility located in Jefferson County, Arkansas; 30 miles southeast of Little Rock and eight miles northwest of Pine Bluff, Arkansas. The arsenal encompasses 14,956 acres of land, most of which (61 percent) is designated as open space/clearance zones. Most of this area is managed for forest products under the arsenal`s timber management program. Approximately 21 percent of the facility supports the munitions supply and storage operations (18 percent conventional munitions, 3 percent chemical agent and munitions). Six percent of the facility contains the conventional munitions maintenance and production areas. The remaining 15 percent of the property is comprised of other administrative, operational, and housing areas along with the Food and Drug Administration`s National Center for Toxicological Research. The arsenal has been in operation since 1941 and has been storing lethal unitary chemical agents since 1942. The arsenal is one of eight sites that stores lethal unitary agents in the United States.

  3. Characteristics of suspended sediment in the San Juan River near Bluff, Utah

    USGS Publications Warehouse

    Thompson, K.R.; Mundorff, J.C.

    1982-01-01

    Fluvial-sediment data were collected for the San Juan River near Bluff beginning in 1914 and terminating in 1980. A double-mass curve showed a change in relationship between annual suspended-sediment discharge and annual stream discharge between the water years 1941-44 and 73. Possible causes for these changes in laboratory procedures, and unusually large runoff that occurred in 1941 and 1972. An unknown or unidentified factor may also be involved. The actual reason for this change in relationship may never be fully understood. Navajo Dam apparently has had no significant effect on fluvial sediment at the sampling site. Mean annual suspended sediment discharge in the San Juan River near Bluff was about 25,410,000 tons ranging from 3,234,000 tons in 1978 to 112,400,000 tons in 1941. The use of annual stream discharge to predict annual suspended-sediment discharge at the site will produce poor results because of size and diversity of the basin and the quality of records available. A positive correlation exists between sand concentration and stream discharge at this site, however, considerable variability is evident. This relationship does not exist when stream discharge exceeds 6,000 cubic feet per second. It is recommended that if collection of suspended-sediment records be resumed in this reach of the river an alternative sampling site should be selected and the use of pumping samplers considered because of the remoteness of the area. (USGS)

  4. Power production locality of bluff body flutter mills using fully coupled 2D direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Kuhl, J. M.; Desjardin, P. E.

    2012-01-01

    Two-dimensional, fully coupled direct numerical simulations (DNS) are conducted to examine the local energy dynamics of a flexible cantilevered plate in the wake of a two-dimensional circular cylinder. The motion of the cantilevered plate is described using a finite element formulation and a fully compressible, finite volume Navier Stokes solver is used to compute the flow field. A sharp interface level set method is employed in conjunction with a ghost fluid method to describe the immersed boundaries of the bluff body and flexible plate. DNS is first conducted to validate the numerical methodology and compared with previous studies of flexible cantilevered plates and flow over bluff bodies; excellent agreement with previous results is observed. A newly defined power production/loss geometry metric is introduced based on surface curvature and plate velocity. The metric is found to be useful for determining which sections of the plate will produce energy based on curvature and deflection rate. Scatter plots and probability measures are presented showing a high correlation between the direction of energy transfer (i.e., to or from the plate) and the sign of the newly defined curvature-deflection-rate metric. The findings from this study suggest that a simple local geometry/kinematic based metric can be devised to aid in the development and design of flexible wind energy harvesting flutter mills.

  5. 33 CFR 207.169 - Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207.169 Section 207.169 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.169 Oklawaha River,...

  6. 33 CFR 207.169 - Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207.169 Section 207.169 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.169 Oklawaha River,...

  7. 33 CFR 207.169 - Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207.169 Section 207.169 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.169 Oklawaha River,...

  8. The Illinois Natural Heritage Conservation Education Kit V. [Ecology and Management of Special Habitats: Dune, Cave, Cliff, Bluff, and Urban.

    ERIC Educational Resources Information Center

    Stone, Sally F.

    The ecology and management of special habitats is the theme of this instructional guide. It contains 24 activities designed to help teachers familiarize their students with dune, cave, cliff, bluff, and urban habitats in Illinois. Each activity (which is ready to be copied and given to students) includes an objective (called a mission) and

  9. Calvert Cliffs Nuclear Power Plant Life Cycle Management/License Renewal Program: Structure scoping and aging management review: Volume 2. Final report

    SciTech Connect

    Doroshuk, B.W.; Tilden, B.M.; Tucker, R.L.; Hostetler, D.R.

    1995-10-01

    Central to the Life Cycle Management (LCM) Program for the Calvert Cliffs Nuclear Power Plant (CCNPP) plant is its Integrated Plant Assessment (EPA) process. The IPA is a comprehensive, systematic evaluation of the effectiveness of age-related degradation management for the plant`s important systems, structures, and components. Components of structures are identified as functionally important and within the scope of license renewal in the scoping (screening) step and are evaluated to determine if they are subject to aging management review. For those that are, further evaluations of aging issues are performed. At Calvert Cliffs, a detailed methodology and procedures for conducting component level scoping and evaluations of structures have been developed and thoroughly tested. The development and application of these procedures have resolved problems that other utilities can avoid by adapting these methods to their own plants. In recognition of this, the CCNPP LCM processes and results are being presented in a series of EPRI reports. The first report of this series, which provided an overview of the then current CCNPP LCM/IPA process, will be revised to reflect the final CCNPP process. This report, which is another in the CCNPP LCM series of EPRI reports, describes the methodology for performing scoping and component aging management reviews for structures. A review of the CCNPP processes will assist other nuclear power plant operators in establishing their own LCM programs. This Volume 2 provides appendices F through T and Attachments 1 through 8 of this report.

  10. Calvert Cliffs Nuclear Power Plant life cycle management/license renewal program: Structure scoping and aging management review. Volume 1, Final report

    SciTech Connect

    Doroshuk, B.W.; Tilden, B.M.; Tucker, R.L.; Hostetler, D.R.

    1995-10-01

    Central to the Life Cycle Management (LCM) Program for the Calvert Cliffs Nuclear Power Plant (CCNPP) plant is its Integrated Plant Assessment (IPA) process. The IPA is a comprehensive, systematic evaluation of the effectiveness of age-related degradation management for the plant`s important systems, structures, and components. Components of structures are identified as functionally important and within the scope of license renewal in the scoping (screening) step and are evaluated to determine if they are subject to aging management review. For those that are, further evaluations of aging issues are performed. At Calvert Cliffs, a detailed methodology and procedures for conducting component level scoping and evaluations of structures have been developed and thoroughly tested. The development and application of these procedures have resolved problems that other utilities can avoid by adapting these methods to their own plants. In recognition of this, the CCNPP LCM processes and results are being presented in a series of EPRI reports. The first report of this series, which provided an overview of the then current CCNPP LCM/IPA process, will be revised to reflect the final CCNPP process. This first set of steps in the IPA process, scoping, (called screening in earlier versions of the LR rule), identifies systems, structures, and components that are within the scope of license renewal.

  11. Alteration and geochemical zoning in Bodie Bluff, Bodie mining district, eastern California

    USGS Publications Warehouse

    Herrera, P.A.; Closs, L.G.; Silberman, M.L.

    1993-01-01

    Banded, epithermal quartz-adularia veins have produced about 1.5 million ounces of gold and 7 million ounces of silver from the Bodie mining district, eastern California. The veins cut dacitic lava flows, pyroclastic rocks and intrusions. Sinter boulders occur in a graben structure at the top of Bodie Bluff and fragments of sinter and mineralized quartz veins occur in hydrothermal breccias nearby. Explosive venting evidently was part of the evolution of the ore-forming geothermal systems which, at one time, must had reached the paleosurface. Previous reconnaissance studies at Bodie Bluff suggested that the geometry of alteration mineral assemblages and distribution of some of the major and trace elements throughout the system correspond to those predicted by models of hot-spring, volcanic rock hosted precious metal deposits (Silberman, 1982; Silberman and Berger, 1985). The current study was undertaken to evaluate these sugestions further. About 500 samples of quartz veins and altered rocks, including sinter, collected over a vertical extent of 200 meters within Bodie Bluff were petrographically examined and chemically analyzed for trace elements by emission spectrographic and atomic absorption methods. Sixty-five samples were analyzed for major elements by X-ray fluorescence methods. The results of these analyses showed that, in general, alteration mineral assemblage and vertical geochemical zoning patterns follow those predicted for hot-spring deposits, but that geochemical zoning patterns for sinter and quartz veins (siliceous deposits), and altered wall rocks are not always similar. The predicted depth-concentration patterns for some elements, notably Au, Ag, Hg, and Tl in quartz veins, and Hg, As and Ag in wall rocks were not as expected, or were perturbed by the main ore producing zone. For both quartz veins and altered wall rocks, the main ore zone had elevated metal contents. Increased concentration of many of these elements could indicate proximity to this zone. However, irregularities in the distribution of some key elements, such as Au and Ag, relative to the predictive models suggest that a larger suite of elements be considered for exploration for ore zones within the district. ?? 1993.

  12. High-Speed Linear Raman Spectroscopy for Instability Analysis of a Bluff Body Flame

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Fischer, David

    2013-01-01

    We report a high-speed laser diagnostics technique based on point-wise linear Raman spectroscopy for measuring the frequency content of a CH4-air premixed flame stabilized behind a circular bluff body. The technique, which primarily employs a Nd:YLF pulsed laser and a fast image-intensified CCD camera, successfully measures the time evolution of scalar parameters (N2, O2, CH4, and H2O) in the vortex-induced flame instability at a data rate of 1 kHz. Oscillation of the V-shaped flame front is quantified through frequency analysis of the combustion species data and their correlations. This technique promises to be a useful diagnostics tool for combustion instability studies.

  13. Monte Carlo studies for neutrino detection from Minna Bluff and other mountainsides in Antarctica

    NASA Astrophysics Data System (ADS)

    Barrella, Taylor; Vieregg, Abigail; Saltzberg, David; Anita Collaboration

    2011-04-01

    We present a simple Monte Carlo simulation for a possible neutrino detection experiment. The detector would be composed of an array of radio antennas on Minna Bluff, Antarctica, designed to detect Cherenkov radiation from ultra-high-energy neutrinos. The location, overlooking the Ross Ice Shelf, is ideal because of its proximity to McMurdo station. We show the validity of the results by comparing with the Monte Carlo simulation established for the ANITA (Antarctic Impulsive Transient Antenna) experiment. We also present new results on an attenuation length measurement of the ice shelf in the 200-1200 MHz range. Though the results predict less than one event per year, we discovered a possible alternative of placing the detector on the Transantarctic Mountains to overlook the deeper ice sheet.

  14. Numerical Investigation of Base Drag for an Axisymmetric Underwater Vehicle with Bluff Afterbody

    NASA Astrophysics Data System (ADS)

    Kim, Min-Jae; Lee, Kurnchul

    2009-11-01

    The objective of this study is to predict the drag of an axisymmetric underwater vehicle with bluff afterbody. FLUENT, commercial CFD code, is used to simulate high Reynolds number turbulent flows around the vehicle. The computed drag coefficients are compared to available experimental data at various Reynolds numbers. Four widely used two-equation turbulence models are investigated to evaluate their performance of predicting the anisotropic turbulence in a recirculating flow region, which is caused by flow separation arising from the base of the vehicle. The simulations with Realizable k-? and k-? SST turbulence models predict the anisotropic turbulent flows comparatively well and the drag prediction results with those models show good agreements with the experimental data.

  15. Wavelet-based adaptive numerical simulation of unsteady 3D flow around a bluff body

    NASA Astrophysics Data System (ADS)

    de Stefano, Giuliano; Vasilyev, Oleg

    2012-11-01

    The unsteady three-dimensional flow past a two-dimensional bluff body is numerically simulated using a wavelet-based method. The body is modeled by exploiting the Brinkman volume-penalization method, which results in modifying the governing equations with the addition of an appropriate forcing term inside the spatial region occupied by the obstacle. The volume-penalized incompressible Navier-Stokes equations are numerically solved by means of the adaptive wavelet collocation method, where the non-uniform spatial grid is dynamically adapted to the flow evolution. The combined approach is successfully applied to the simulation of vortex shedding flow behind a stationary prism with square cross-section. The computation is conducted at transitional Reynolds numbers, where fundamental unstable three-dimensional vortical structures exist, by well-predicting the unsteady forces arising from fluid-structure interaction.

  16. Flow and mixing structures in bluff-body stabilized gas flames

    SciTech Connect

    Namazian, M.; Kelly, J.; Schefer, R.W.; Johnston, S.C.; Long, M.B.

    1986-01-01

    The mixing and combustion process has been studied in a bluff-body stabilized, nonpremixed flame using direct flame photography and planar flow visualization. The burner consisted of a central jet of CH4 and an outer coflowing air stream. Direct flame photography was used to study the effects of fuel and air flowrate on the global characteristics of the flame. Planar flow visualization techniques using Mie scattering from seed particles added to the fuel jet and Raman scattering from C4 provided information on the interaction between turbulent mixing and combustion chemistry. The results show that the flow is highly three dimensional. Roll-up structures, which form randomly, are evident on the fuel and combustion air boundaries. Stabilization of the flame is dominated by large-scale turbulent mixing structures which are irregular and time-varying. 4 figs.

  17. Energy harvesting of wind-driven piezoelectric membranes in the wake of bluff bodies.

    NASA Astrophysics Data System (ADS)

    Novak, Todd; Marusic, Ivan; Robbins, William

    2006-11-01

    In recent years a unique method of passive energy harvesting has been developed for off-grid applications. This method utilizes piezoelectric membranes, commonly called piezoelements or bimorphs, placed in a fluid flow. The resulting strain from the periodic undulations of the membrane is converted into a voltage across the surfaces of the membrane via the piezoelectric effect. In our present study we have examined the oscillatory nature of the membrane when placed in the wake of a bluff body in an air flow. Our aim has been to determine the appropriate geometry and spacing given a range of wind speeds such as to achieve optimal power harvesting. We present results from experiments using high-speed digital photography and hotwire anemometry where we analyze the motion of the membrane under varying wind speeds, aspect ratios, and membrane stiffness.

  18. A dry-surface coating method for visualization of separation. [bluff bodies

    NASA Technical Reports Server (NTRS)

    Sadeh, W. Z.; Brauer, H. J.; Durgin, J. R.

    1980-01-01

    A relatively simple and reasonably accurate dry-surface coating method for visualization of the separation line on a bluff body was devised and successfully tested. This technique is based on the color reaction of a dry film containing a pH indicator with an appropriate gas released in the body wake. The dry-surface coating method is effective at any Reynolds number and for both incident laminar and turbulent flows. It further supplies a colorful permanent of consistently good photographic quality of the separation line. The effectiveness and accuracy of this technique were tested in visualizing the separation angle on a circular cylinder in both laminar and turbulent crossflows at subcritical Reynolds numbers. Separation angles revealed by the visualization were within + or - 4 percent of their counterparts deduced from the mean wall pressure distribution.

  19. Calculations of turbulent mass transport in a bluff-body diffusion-flame combustor

    NASA Technical Reports Server (NTRS)

    Sturgess, G. J.; Mcmanus, K. R.

    1984-01-01

    Experimental measurements of turbulent mass transit in a bluff-body diffusion-flame combustor (using CO2 instead of fuel) are analyzed to evaluate the accuracy of physical models used in flow computations. The data of Lightman and Magill (1981), Lightman et al. (1983), and Roquemore et al. (1983) are used to calculate apparent turbulent Schmidt numbers (TSN) for a series of flow conditions by a modified TEACH viscous-flow code. The modeling principles, calculation grid, and boundary conditions are discussed, and the results are presented in graphs comparing calculated and measured values. It is shown that models such as the two-equation (K - epsilon) model which use a single value of the TSN are inappropriate for conditions typical of gas-turbine combustors: local TSN variations due to turbulence behavior must be taken into account in improved models.

  20. Experimental and Numerical Investigation of Flow Structures around Cylindrical Bluff Bodies

    NASA Astrophysics Data System (ADS)

    Yagmur, Sercan; Dogan, Sercan; Aksoy, Muharrem H.; Canli, Eyub; Ozgoren, Muammer

    2015-05-01

    The understanding and quantitative prediction of velocity and pressure fluctuations in turbulent flows around such bluff bodies have been evolving over the years. The main aim of the present work is to investigate experimentally and numerically the flow field in the wake region of different bluff bodies such as circular, square and triangle cross section cylinders placed horizontally perpendicular to the uniform flow. The experimental studies were performed by Particle Image Velocimetry (PIV) method in an open water channel at Reynolds numbers 5000 and 10000 defined according to the characteristic lengths of the cylinders in the facilities of Selcuk University of Advanced Technology Research and Application Center in Turkey. The experimental results are compared to the numerical results obtained by means of transient simulation with LES turbulence model of ANSYS-Fluent Software. It is shown that the numerical and experimental results have a good agreement in respect of the instantaneous and time-averaged flow field patterns of vorticity, velocity component streamwise direction and streamline topology. In addition, drag coefficient of the geometries were also numerically calculated. For all geometries the wake length in x and y directions and size of the foci of the streamlines are decreasing by increasing Reynolds numbers in time-averaged results. The time-averaged flow patterns of both experimental and numerical results have considerable symmetry with respect to the centerline of each cylinder. Contours of the time-averaged stream wise velocity for Re=10000 demonstrate that the stagnation point around the symmetry plane moves further upstream for all cylinders in accordance with Re=5000. The maximum drag coefficient value was yielded for the square cross-section cylinder as 1.78 due to the sharp-edged geometry.

  1. Experimental investigation of galloping piezoelectric energy harvesters with square bluff bodies

    NASA Astrophysics Data System (ADS)

    Ewere, Felix; Wang, Gang; Cain, Brian

    2014-10-01

    In this paper, both a baseline galloping piezoelectric energy harvester (GPEH) with a square bluff body and an improved GPEH with an impact bump stop are tested in a wind tunnel in order to determine the system damping, electrical response and limit cycle oscillation (LCO) amplitude. In the baseline GPEH, harvested voltage, LCO amplitude and damping ratio vary with wind velocity and electrical load. They all increase with increasing wind velocity under the same electrical load. Under each wind velocity, the damping ratio increases from the short circuit load, reaches a peak value at the electrical load resulting in a maximum voltage, and reduces the value at the open circuit load. The LCO amplitude shows the opposite trend compared to the damping case. It decreases as the electrical resistance load increases and reaches the minimum value when the damping ratio is highest. A resistance load of 100 k? yields a maximum peak power output. The impact stop is introduced to reduce bending stresses and improve the fatigue life of the baseline GPEH. The performance of the improved GPEH depends on the stop design parameters such as gap size, stop location and contact area. Comprehensive tests were conducted to investigate the effect of each parameter on the performance of the improved GPEH and an optimal bump stop configuration was determined. Compared to the expected proportional reduction in both electrical and structural responses, a maximum 70% reduction in LCO amplitude and only a maximum 20% reduction in harvested voltage are achieved in our optimal improved GPEH. The time variable and motion dependent aerodynamic forces acting on the bluff body could contribute to this. In summary, comprehensive experimental evaluations were conducted to characterize the performance of both baseline GPEHs and improved GPEHs. The baseline GPEH service life can be significantly improved by incorporating an impact bump stop. The improved GPEH design provides a practical solution to harvest electricity from wind-induced vibration.

  2. Response dynamics of bluff-body stabilized conical premixed turbulent flames with spatial mixture gradients

    SciTech Connect

    Chaudhuri, Swetaprovo; Cetegen, Baki M.

    2009-03-15

    Response of bluff-body stabilized conical turbulent premixed flames was experimentally studied for a range of excitation frequencies (10-400 Hz), mean flow velocities (5, 10 and 15 m/s) and three different spatial mixture distributions (uniform, inner and outer enrichment). Upstream excitation was provided by a loudspeaker producing velocity oscillation amplitudes of about 8% of the mean flow velocity. Flame response was detected by a photomultiplier observing the CH{sup *} emission from the flame. The studied turbulent flames exhibited transfer function characteristics of a low-pass filter with a cutoff Strouhal number between 0.08 and 0.12. The amplification factors at low frequencies ranged from 2 to 20 and generally increased for mean flow velocities from 5 to 15 m/s. The highest levels of amplification were found for the outer mixture enrichment followed in decreasing order by uniform and inner mixture gradient cases. The high levels of flame response for the outer enrichment case were attributed to the enhanced flame-vortex interaction in outer jet shear layer. At high excitation levels (u{sup '}/U{sub m}{approx}0.3) for U{sub m}=5 m/ s where non-linear flame response is expected, the flame exhibited a reduced amplitude response in the frequency range between 40 and 100 Hz for the uniform and outer equivalence ratio gradient cases and no discernible effect for the inner equivalence ratio gradient. In all cases, transfer function phase was found to vary linearly with excitation frequency. Finally, a relationship between the amplitude characteristics of the bluff-body wake transfer function and flame blowoff equivalence ratio was presented. (author)

  3. Eulerian particle flamelet modeling of a bluff-body CH{sub 4}/H{sub 2} flame

    SciTech Connect

    Odedra, Anand; Malalasekera, W.

    2007-11-15

    In this paper an axisymmetric RANS simulation of a bluff-body stabilized flame has been attempted using steady and unsteady flamelet models. The unsteady effects are considered in a postprocessing manner through the Eulerian particle flamelet model (EPFM). In this model the transient history of scalar dissipation rate, conditioned by stoichiometric mixture fraction, is required to generate unsteady flamelets and is obtained by tracing Eulerian particles. In this approach unsteady convective-diffusive transport equations are solved to consider the transport of Eulerian particles in the domain. Comparisons of the results of steady and unsteady calculations show that transient effects do not have much influence on major species, including OH, and the structure of the flame therefore can be successfully predicted by steady or unsteady approaches. However, it appears that slow processes such as NO formation can only be captured accurately if unsteady effects are taken into account, while steady simulations tend to overpredict NO. In this work turbulence has been modeled using the Reynolds stress model. Predictions of velocity, velocity rms, mean mixture fraction, and its rms show very good agreement with experiments. Performance of three detailed chemical mechanisms, the GRI Mech 2.11, the San Diego mechanism, and the GRI Mech 3.0, has also been evaluated in this study. All three mechanisms performed well with both steady and unsteady approaches and produced almost identical results for major species and OH. However, the difference between mechanisms and flamelet models becomes clearly apparent in the NO predictions. The unsteady model incorporating the GRI Mech 2.11 provided better predictions of NO than steady calculations and showed close agreement with experiments. The other two mechanisms showed overpredictions of NO with both unsteady and steady models. The level of overprediction is severe with the steady approach. GRI Mech 3.0 appears to overpredict NO by a factor of 2 compared to GRI Mech 2.11. The NO predictions by the San Diego mechanism fall between those of the two GRI mechanisms. The present study demonstrates the success of the EPFM model and when used with the GRI 2.11 mechanism predicts all flame properties and major and minor species very well, and most importantly the correct NO levels. (author)

  4. Theoretical analysis and experimental verification on valve-less piezoelectric pump with hemisphere-segment bluff-body

    NASA Astrophysics Data System (ADS)

    Ji, Jing; Zhang, Jianhui; Xia, Qixiao; Wang, Shouyin; Huang, Jun; Zhao, Chunsheng

    2014-05-01

    Existing researches on no-moving part valves in valve-less piezoelectric pumps mainly concentrate on pipeline valves and chamber bottom valves, which leads to the complex structure and manufacturing process of pump channel and chamber bottom. Furthermore, position fixed valves with respect to the inlet and outlet also makes the adjustability and controllability of flow rate worse. In order to overcome these shortcomings, this paper puts forward a novel implantable structure of valve-less piezoelectric pump with hemisphere-segments in the pump chamber. Based on the theory of flow around bluff-body, the flow resistance on the spherical and round surface of hemisphere-segment is different when fluid flows through, and the macroscopic flow resistance differences thus formed are also different. A novel valve-less piezoelectric pump with hemisphere-segment bluff-body (HSBB) is presented and designed. HSBB is the no-moving part valve. By the method of volume and momentum comparison, the stress on the bluff-body in the pump chamber is analyzed. The essential reason of unidirectional fluid pumping is expounded, and the flow rate formula is obtained. To verify the theory, a prototype is produced. By using the prototype, experimental research on the relationship between flow rate, pressure difference, voltage, and frequency has been carried out, which proves the correctness of the above theory. This prototype has six hemisphere-segments in the chamber filled with water, and the effective diameter of the piezoelectric bimorph is 30mm. The experiment result shows that the flow rate can reach 0.50 mL/s at the frequency of 6 Hz and the voltage of 110 V. Besides, the pressure difference can reach 26.2 mm H2O at the frequency of 6 Hz and the voltage of 160 V. This research proposes a valve-less piezoelectric pump with hemisphere-segment bluff-body, and its validity and feasibility is verified through theoretical analysis and experiment.

  5. Terrestrial LIDAR investigation of the December 2003 and January 2007 activations of the Northridge Bluff landslide, Daly City, California

    USGS Publications Warehouse

    Collins, Brian D.; Kayen, Robert; Reiss, Thomas; Sitar, Nicholas

    2007-01-01

    On December 20, 2003 and again on January 1, 2007, landslides occurred along the coastal bluff that forms the west boundary of Daly City, California sending debris as far as 290 meters downhill and 90 meters into the ocean. This area is known for large landslide events where 150-meter tall coastal bluffs extend southward along the west boundary of San Francisco and San Mateo Counties (Fig. 1). The 2003 and 2007 landslide events occurred west of Northridge Drive in Daly City and just south of Avalon Canyon, which bisects the bluffs in this area (Fig. 2). Residential development, utility lines and roads occupy the land immediately east of this location. As part of a comprehensive project to investigate the failure mechanisms of coastal bluff landslides in weakly lithified sediments along the west coast of the United States, members of the U.S. Geologic Survey (USGS) Coastal and Marine Geology (CMG) Program performed reconnaissance mapping of these landslide events including collection of high-resolution topographic data using CMG's terrestrial LIDAR laser scanning system. This report provides a brief background on each landslide event and presents topographic datasets collected following each event. Downloadable contour data, images, and FGDC-compliant metadata of the surfaces generated from the LIDAR data are also provided. LIDAR data collection and processing techniques used to generate the datasets are outlined. Geometric and volumetric measurements are also presented along with high-resolution cross-sections through various areas of the slide masses and discussion concerning the slides present (2007) configuration is provided.

  6. Long-term benthic monitoring programs near the Morgantown and Calvert Cliffs power plants - third annual report. Volume 2. Appendices. Annual report, July 1982-June 1983

    SciTech Connect

    Holland, A.F.; Hiegel, M.H.; Shaughnessy, A.T.; Stroup, C.F.; Ross, E.A.

    1985-01-01

    Macrobenthos and physical/chemical factors known to affect their abundance were monitored near the Calvert Cliffs nuclear power plant on the mainstem of the Chesapeake Bay between 1971 and 1982. These data, along with data collected near the Morgantown power plant on the Potomac between 1980 and 1983, were used to quantify the variation in macrobenthos due to natural spatial patterns, seasonal dynamics, year-to-year fluctuations in abundance, and power plant operations, as well as to determine if long-term trends in populations or communities occurred. Macrobenthic community structure was persistent over the 11 years within bounds determined chiefly by year-to-year variation in salinity and dissolved oxygen concentration. Most of the species responded to changes in salinity by predictable increases or decreases in abundance.

  7. Long-term benthic monitoring programs near the Morgantown and Calvert Cliffs power plants - third annual report. Volume 1. Text. Annual report, July 1982-June 1983

    SciTech Connect

    Holland, A.F.; Hiegel, M.H.; Shaughnessy, A.T.; Stroup, C.F.; Ross, E.A.

    1985-01-01

    Macrobenthos and physical/chemical factors known to affect their abundance were monitored near the Calvert Cliffs nuclear power plant on the mainstem of the Chesapeake Bay between 1971 and 1982. These data, along with data collected near the Morgantown power plant on the Potomac between 1980 and 1983, were used to quantify the variation in macrobenthos due to natural spatial patterns, seasonal dynamics, year-to-year fluctuations in abundance, and power plant operations, as well as to determine if long-term trends in populations or communities occurred. Macrobenthic community structure was persistent over the 11 years within bounds determined chiefly by year-to-year variation in salinity and dissolved oxygen concentration. Most of the species responded to changes in salinity by predictable increases or decreases in abundance.

  8. Environmental radionuclide concentrations in the vicinity of the Calvert Cliffs Nuclear Power Plant and the Peach Bottom Atomic Power Station: 1996--1997. Final report

    SciTech Connect

    McLean, R.I.; Jones, T.S.

    1998-11-20

    The Maryland Power Plant Research Program monitors concentrations of natural, weapons, and power plant produced radionuclides in environmental samples collected from the Chesapeake Bay in the vicinity of the Calvert Cliffs Nuclear Power Plant (CCNPP) and from the Susquehanna River-Chesapeake Bay system in the vicinity of Peach Bottom Atomic Power Station (PBAPS). The purpose of this monitoring is to determine the fate, transport, and potential effects of power plant-produced radionuclides. This report contains a description of monitoring activities and data collected during the 1996 and 1997 calendar years. Radionuclide concentrations in shellfish, finfish, aquatic vegetation, and sediment were measured using high-resolution gamma spectrometry. Radionuclides in environmental samples originated from natural sources, historic atmospheric weapons testing, and normal operations of CCNPP and PBAPS.

  9. Boattail Plates With Non-Rectangular Geometries For Reducing Aerodynamic Base Drag Of A Bluff Body In Ground Effect

    DOEpatents

    Ortega, Jason M. (Pacifica, CA); Sabari, Kambiz (Livermore, CA)

    2006-03-07

    An apparatus for reducing the aerodynamic base drag of a bluff body having a leading end, a trailing end, a top surface, opposing left and right side surfaces, and a base surface at the trailing end substantially normal to a longitudinal centerline of the bluff body, with the base surface joined (1) to the left side surface at a left trailing edge, (2) to the right side surface at a right trailing edge, and (3) to the top surface at a top trailing edge. The apparatus includes left and right vertical boattail plates which are orthogonally attached to the base surface of the bluff body and inwardly offset from the left and right trailing edges, respectively. This produces left and right vertical channels which generate, in a flowstream substantially parallel to the longitudinal centerline, respective left and right vertically-aligned vortical structures, with the left and right vertical boattail plates each having a plate width defined by a rear edge of the plate spaced from the base surface. Each plate also has a peak plate width at a location between top and bottom ends of the plate corresponding to a peak vortex of the respective vertically-aligned vortical structures.

  10. Spatio-temporal Dynamics of Coastal Bluff Erosion near Barrow Alaska over the Past Decade

    NASA Astrophysics Data System (ADS)

    Kofoed, K. B.; Lopez, A. F.; Aguirre, A.; Aiken, Q.; Cody, R. P.; Gaylord, A. G.; Manley, W. F.; Green, E.; Nelson, L.; Lougheed, V.; Velasco, A. A.; Tweedie, C. E.

    2014-12-01

    Arctic coastal systems are recognized as being one of the most climate change - vulnerable ecosystems on Earth and represent a complex nexus for examining change at the interface between marine, terrestrial, atmospheric, cryospheric and social systems. Although coastal erosion has received increased attention in the Arctic, few studies have examined the fine scale spatiotemporal dynamics and variability in erosion rates relative to the range of factors that act concomitantly to control erosion (e.g. duration of ice free seas, bathymetry, wave action, sea and air temperature, landscape morphology). This study reports on the spatiotemporal dynamics of annual DGPS surveys of eroding coastal bluffs in northern Alaska near the city of Barrow. Surveys along ca. 11km of the Elson Lagoon coast have been conducted since 2002 and additional surveys along ca. 120km of Elson Lagoon and Chuckhi Sea coast have been conducted since 2013. There has been strong inter-annual spatiotemporal variability in erosion rates with no indication of a long term change in erosion rates over time. Factors controlling wave intensity (e.g. wind run, off shore bathymetry, aspect of the coast relative to prevailing winds) explain most variability in erosion rates over time but during relatively calm periods, landscape history and morphology become more important. These findings highlight the extreme fine scale spatiotemporal heterogeneity in erosion rates along the Arctic Coast, and the importance of incorporating both storm-related climatic events and landscape characteristics when forecasting future environmental states in Arctic coastal landscapes. Case studies outlining new remote sensing technologies and future directions of study will also be outlined including terrestrial and airborne LiDAR, and Kite, UAV, and satellite imagery that is being used to derive and monitor topographic and hydrological change near eroding coastal bluffs; a wireless sensor network of micrometeorological and optical sensors; low cost tri-axial accelerometers that measure wave amplitude, period and azimuth; a survey vessel for mapping near shore bathymetry and water chemistry; and a web-based decision tool for improving management and planning of the coastal zone near Barrow.

  11. Multi-Point Velocity Correlations in the Wake of a Three-Dimensional Bluff Body

    NASA Astrophysics Data System (ADS)

    Shea, Patrick; Glauser, Mark

    2013-11-01

    Three-dimensional bluff-bodies known as turrets are commonly used for housing optical systems on airborne platforms. These geometries generate highly turbulent wakes that decrease the performance of the optical systems and the aircraft. The current experimental study used dynamic suction in both open and closed-loop control configurations to actively control the wake turret. The experiments were carried out at a Reynolds number of 5 105, and the flow field was characterized using stereoscopic PIV measurements acquired in the wake of the turret. These data were processed using traditional single-point statistics which showed that the active control system was able to significantly alter the wake of the turret. Using multi-point correlations, turbulent characteristics such as the integral length scale can be calculated. For the turret wake, estimates of the integral length scales were found to be highly dependent upon the region of the flow that was evaluated, especially when comparing the shear layers to the center of the wake. With the application of the active control, the integral length scales were generally found to increase.

  12. Large eddy simulation of forced ignition of an annular bluff-body burner

    SciTech Connect

    Subramanian, V.; Domingo, P.; Vervisch, L.

    2010-03-15

    The optimization of the ignition process is a crucial issue in the design of many combustion systems. Large eddy simulation (LES) of a conical shaped bluff-body turbulent nonpremixed burner has been performed to study the impact of spark location on ignition success. This burner was experimentally investigated by Ahmed et al. [Combust. Flame 151 (2007) 366-385]. The present work focuses on the case without swirl, for which detailed measurements are available. First, cold-flow measurements of velocities and mixture fractions are compared with their LES counterparts, to assess the prediction capabilities of simulations in terms of flow and turbulent mixing. Time histories of velocities and mixture fractions are recorded at selected spots, to probe the resolved probability density function (pdf) of flow variables, in an attempt to reproduce, from the knowledge of LES-resolved instantaneous flow conditions, the experimentally observed reasons for success or failure of spark ignition. A flammability map is also constructed from the resolved mixture fraction pdf and compared with its experimental counterpart. LES of forced ignition is then performed using flamelet fully detailed tabulated chemistry combined with presumed pdfs. Various scenarios of flame kernel development are analyzed and correlated with typical flow conditions observed in this burner. The correlations between, velocities and mixture fraction values at the sparking time and the success or failure of ignition, are then further discussed and analyzed. (author)

  13. A rotating, bluff-body disc for reduced variability in wind tunnel aerosol studies

    PubMed Central

    Koehler, Kirsten A.; Anthony, T. Renee; van Dyke, Michael; Volckens, John

    2016-01-01

    A rotating bluff-body disc (RBD) was developed to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. The RBD is designed to rotate eight personal aerosol samplers around a circular path in a forward-facing plane aligned with the wind tunnel cross section. Rotation of the RBD allows each sampler to traverse an identical path about the wind tunnel cross section, which reduces the effects of spatial heterogeneity associated with dispersing supermicron aerosol in low-velocity wind tunnels. Samplers are positioned on the face of the RBD via sampling ports, which connect to an air manifold on the back of the disc. Flow through each sampler was controlled with a critical orifice or needle valve, allowing air to be drawn through the manifold with a single pump. A metal tube, attached to this manifold, serves as both the axis of rotation and the flow conduction path (between the samplers and the vacuum source). Validation of the RBD was performed with isokinetic samplers and 37-mm cassettes. For facing-the-wind tests, the rotation of the RBD significantly decreased intra-sampler variability when challenged with particle diameters from 1 to 100 μm. The RBD was then employed to determine the aspiration efficiency of Institute of Occupational Medicine (IOM) personal samplers under a facing-the-wind condition. Operation of IOM samplers on the RBD reduced the between-sampler variability for all particle sizes tested. PMID:21097990

  14. Erosional history of Cape Halkett and contemporary monitoring of bluff retreat, Beaufort Sea coast, Alaska

    USGS Publications Warehouse

    Jones, Benjamin M.; Arp, Christopher D.; Beck, Richard A.; Grosse, Guido; Webster, James M.; Urban, Frank E.

    2009-01-01

    Cape Halkett is located along the Beaufort Sea at the end of a low-lying tundra landscape. The area has been subject to major modifications over the last century as a result of erosion and migration of the coastline inland. Long-term mean annual erosion rates (1955-2009) for the entire cape are 7.6 m/yr, with a gradual increase in rates over the first five time periods of remotely sensed imagery analyzed and a large increase during the most recent time period. Division of the cape into three distinct coastal zones shows very different erosional patterns: the northeast-facing segment (Zone 1) showing a consistent and large increase; the southeast-facing segment (Zone 3) showing a gradual increase with recent, heightened erosion rates; and the east-facing segment (Zone 2) showing decreased rates due to the reformation of a sand and gravel spit. Monitoring of bluff erosion with time-lapse photography, differential GPS surveys, terrestrial and bathymetric surveys, and water level, sea and permafrost temperature data provide insights into the processes driving contemporary patterns of erosion and will provide valuable information for the prediction of future shoreline positions.

  15. A rotating bluff-body disc for reduced variability in wind tunnel aerosol studies.

    PubMed

    Koehler, Kirsten A; Anthony, T Renee; van Dyke, Michael; Volckens, John

    2011-01-01

    A rotating bluff-body disc (RBD) was developed to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. The RBD is designed to rotate eight personal aerosol samplers around a circular path in a forward-facing plane aligned with the wind tunnel cross section. Rotation of the RBD allows each sampler to traverse an identical path about the wind tunnel cross section, which reduces the effects of spatial heterogeneity associated with dispersing supermicron aerosol in low-velocity wind tunnels. Samplers are positioned on the face of the RBD via sampling ports, which connect to an air manifold on the back of the disc. Flow through each sampler was controlled with a critical orifice or needle valve, allowing air to be drawn through the manifold with a single pump. A metal tube, attached to this manifold, serves as both the axis of rotation and the flow conduction path (between the samplers and the vacuum source). Validation of the RBD was performed with isokinetic samplers and 37-mm cassettes. For facing-the-wind tests, the rotation of the RBD significantly decreased intra-sampler variability when challenged with particle diameters from 1 to 100 ?m. The RBD was then employed to determine the aspiration efficiency of Institute of Occupational Medicine (IOM) personal samplers under a facing-the-wind condition. Operation of IOM samplers on the RBD reduced the between-sampler variability for all particle sizes tested. PMID:21097990

  16. Axisymmetric bluff-body flow: A vortex solver for thin shells

    SciTech Connect

    Strickland, J.H.

    1992-05-01

    A method which is capable of solving the axisymmetric flow field over bluff bodies consisting of thin shells such as disks, partial spheres, rings, and other such shapes is presented in this report. The body may be made up of several shells whose edges are separated by gaps. The body may be moved axially according to arbitrary velocity time histories. In addition, the surfaces may posses axial and radial degrees of flexibility such that points on the surfaces may be allowed to move relative to each other according to some specified function of time. The surfaces may be either porous or impervious. The present solution technique is based on the axisymmetric vorticity transport equation. Physically, this technique simulates the generation of vorticity at body surfaces in the form of discrete ring vortices which are subsequently diffused and convected into the boundary layers and wake of the body. Relatively large numbers of vortices (1000 or more) are required to obtain good simulations. Since the direct calculation of perturbations from large numbers of ring vortices is computationally intensive, a fast multipole method was used to greatly reduce computer processing time. Several example calculations are presented for disks, disks with holes, hemispheres, and vented hemispheres. These results are compared with steady and unsteady experimental data. 45 refs.

  17. Supersonic Flow past Flat- and Concave-Nosed Bluff-Bodies

    NASA Astrophysics Data System (ADS)

    Hiraki, Koju; Hinada, Motoki; Higuchi, Hiroshi

    1996-11-01

    Investigation on supersonic flowfield ahead of and behind axisymmetric bluff-bodies was carried out at ISAS. The effect of concave front surface was first examined using a cup-shaped geometry as well as the blunt-nosed cylinder having various levels of concavity. Nominally a steady, symmetrical detached shock wave formed in front of the body, but under certain conditions, in particular, with increased concavity at higher Mach numbers, unsteady asymmetrical bow shock was also observed. Period of the latter shock oscillation varied over a wide range. This phenomenon is believed to be associated with an often catastrophic breathing phenomenon of supersonic parachute. Multi-point pressure measurements and an oil-flow visualization indicated a presence of off-axis tangential flow inside concavity to be distinguished from symmetric oscillations often cited. Further study is being made both experimentally and numerically. The investigation on supersonic wake behind a disk was started in conjunction and results of the initial phase of the experiment will be discussed. *Part of this study was carried out during HH's stay at ISAS funded by the NSF International Program.

  18. Axisymmetric bluff-body flow: A vortex solver for thin shells

    NASA Astrophysics Data System (ADS)

    Strickland, J. H.

    1992-05-01

    A method which is capable of solving the axisymmetric flow field over bluff bodies consisting of thin shells such as disks, partial spheres, rings, and other such shapes is presented in this report. The body may be made up of several shells whose edges are separated by gaps. The body may be moved axially according to arbitrary velocity time histories. In addition, the surfaces may possess axial and radial degrees of flexibility such that points on the surfaces may be allowed to move relative to each other according to some specified function of time. The surfaces may be either porous or impervious. The present solution technique is based on the axisymmetric vorticity transport equation. Physically, this technique simulates the generation of vorticity at body surfaces in the form of discrete ring vortices which are subsequently diffused and convected into the boundary layers and wake of the body. Relatively large numbers of vortices (1000 or more) are required to obtain good simulations. Since the direct calculation of perturbations from large numbers of ring vortices is computationally intensive, a fast multipole method was used to greatly reduce computer processing time. Several example calculations are presented for disks, disks with holes, hemispheres, and vented hemispheres. These results are compared with steady and unsteady experimental data.

  19. Ballography: A Billion Nanosecond History of the Bee Bluff Impact Crater of South Texas

    NASA Astrophysics Data System (ADS)

    Graham, R. A.

    2006-07-01

    The Bee Bluff Structure of South Texas in Zavala County near Uvalde has been found to exhibit unusual features permitting study of impactites and meteorite impact processes from the standpoint of grain-level, nanosecond shock-compression science. The site is characterized by a thin cap of Carrizo Sandstone covering a thin hard Indio fm calcareous siltstone. A soft calcareous silt lies below the hard cap. Calculations based on the Earth Impact Effects web-based program indicate that the site is best described by a 60 m diameter iron meteorite striking the ground at 11 km/sec. Such an impact into sandstone is expected to produce a shock pressure of 250 GPa. A large release wave originates from the bottom of the hard target with upward moving melt-vaporization waves of solid, liquid and vapor products that become trapped at the impact interface. Numerous distinctive types of impactites result from this `bottom-up' release behavior. Evidence for hydrodynamic instabilities and resulting density gradients are abundant at the impact interface. An unusually valuable breccia sample called `The Uvalde Crater Rosetta Stone' contains at least seven types of impactites in a well defined arrangement that can be used to read the billion nanosecond history of the impact and identify scattered impactites relative to their place in that history.

  20. Quartz and Hydrous Iron Oxides from the Bee Bluff Structure of South Texas

    NASA Astrophysics Data System (ADS)

    Graham, R. A.; Martin, M.; Thadhani, N. N.; Morosin, B.

    2006-07-01

    There is substantial information showing that the Bee Bluff structure is an impact site and that a residual crater can be identified. The thin hard cap of Carrizo Sandstone, Indio fm calcareous silt and a thin layer of iron-rich siltstone leads to impact processes in which the high pressure release wave proceeds promptly upward leading to a trapping of metamorphic products at the impact interface, a `bottom-up' pressure release. Release of water from goethite binder in the sandstone and from the iron-rich siltstone results in supersaturated steam in mixtures with iron and quartz compounds. Samples with quartz and hydrous iron oxide features are examined with optical microscopy, SEM, EDX and XRD. A quartz grain is found with a well defined PDF set. There is widespread amorphous quartz including lechatleriete. Nanocrystals of α-goethite in the acicular form are common. A condensation sphere from the `Uvalde Crater Rosetta Stone' shows a complex mixture of hematite, goethite, and alpha quartz with a trace of trydimite. Numerous samples are yet to be analyzed. The crater appears to have features that can serve as an Earth analog to Mars craters. A companion paper in the present proceedings summarizes prior work, adds new site detail, reports impact-loading analysis, and describes overall features of impactite samples from the site.

  1. Comparative study of micromixing models in transported scalar PDF simulations of turbulent nonpremixed bluff body flames

    SciTech Connect

    Merci, Bart; Roekaerts, Dirk; Naud, Bertrand; Pope, Stephen B.

    2006-07-15

    Numerical simulation results are presented for turbulent jet diffusion flames with various levels of turbulence-chemistry interaction, stabilized behind a bluff body (Sydney Flames HM1-3). Interaction between turbulence and combustion is modeled with the transported joint-scalar PDF approach. The mass density function transport equation is solved in a Lagrangian manner. A second-moment-closure turbulence model is applied to obtain accurate mean flow and turbulent mixing fields. The behavior of two micromixing models is discussed: the Euclidean minimum spanning tree model and the modified Curl coalescence dispersion model. The impact of the micromixing model choice on the results in physical space is small, although some influence becomes visible as the amount of local extinction increases. Scatter plots and profiles of conditional means and variances of thermochemical quantities, conditioned on the mixture fraction, are discussed both within and downstream of the recirculation region. A distinction is made between local extinction and incomplete combustion, based on the CO species mass fraction. The differences in qualitative behavior between the micromixing models are explained and quantitative comparison to experimental data is made. (author)

  2. Biomimetic bluff body drag reduction by self-adaptive porous flaps

    NASA Astrophysics Data System (ADS)

    Mazellier, Nicolas; Feuvrier, Audrey; Kourta, Azeddine

    2012-01-01

    The performances of an original passive control system based on a biomimetic approach are assessed by investigating the flow over a bluff body. This control device consists of a couple of flaps made from the combination of a rigid plastic skeleton coated with a porous fabric mimicking the shaft and the vane of the bird's feathers, respectively. The sides of a square cylinder have been fitted with this system so that each flap can freely rotate around its leading edge. This feature allows the movable flaps to self-adapt to the flow conditions. Comparing both the uncontrolled and the controlled flow, a significant drag reduction ( ?22% on average) has been obtained over a broad range of Reynolds numbers. This improvement is related to the increase of the base pressure in the controlled case. The investigation of the mean flow reveals a noticeable modification of the flow topology at large scale in the vicinity of the controlled cylinder. Meanwhile, the study of the relative motion of both flaps highlights that their dynamics is sensitive to the Reynolds number. Furthermore, the analysis of the flow dynamics at large scale suggests a lock-in coupling between the flap motion and the vortex shedding.

  3. Two-phase measurements of a spray in the wake of a bluff body

    NASA Technical Reports Server (NTRS)

    Rudoff, R. C.; Houser, M. J.; Bachalo, W. D.

    1987-01-01

    The dynamics of spray drop interaction with the turbulent, recirculating wake of a flat disk bluff body were investigated using a phase Doppler particle analyzer to determine drop size and velocity and the gas-phase velocity. Detailed measurements obtained included spray drop size, axial and radial velocity, angle of trajectory, and size-velocity correlations. The gas-phase velocity was determined from seeding of the two-phase flow. Results showed dramatic differences in drop behavior for various size classes when interacting with the turbulent flow field. Small drops were quickly entrained and recirculated, while initially, the larger drops continued in the general direction of the spray cone. Further downstream, significant numbers of large drops recirculated, generating a bifurcated size-velocity correlation. These lateral convections and streamwise accelerations and decelerations strongly influenced the number density along with size and velocity distributions. The complex interaction of the spray with the turbulent air-flow points out the need for spatially-resolved measurements that determine drop behavior for individual size classes, rather than characterizing a spray only via simple integral quantities such as the Sauter mean diameter.

  4. Coherent substructure of turbulence near the stagnation zone of a bluff body

    NASA Technical Reports Server (NTRS)

    Sadeh, W. Z.; Brauer, H. J.

    1980-01-01

    The evolution of freestream turbulence in crossflow about a circular cylinder was studied in order to identify the existence of a coherent substructure which is the outcome of the amplification of freesteam turbulence by the stretching mechanism in diverging flow about a bluff body. Visualization of the flow events revealed the selective stretching of cross-vortex tubes and the emergence of an organized turbulent flow pattern near the cylinder stagnation zone. Significant amplification of the total turbulent energy of the streamwise fluctuating velocity was consistently monitored. Realization of selective amplification at scales larger than the neutral scale of the stagnation flow was indicated by the variation of the discrete streamwise turbulent energy. A most amplified scale, characteristic of the energy containing eddies within the coherent substructure and commensurate with the boundary-layer thickness, was detected. Penetration of the amplified turbulence into the cylinder boundary layer led to the retardation of separation and to a concurrent decrease in the drag coefficient at subcritical cylinder-diameter Reynolds numbers.

  5. Long-term benthic monitoring programs near the Morgantown and Calvert Cliffs power plants - annual report for the first year's studies. Volume III: appendices A-E. Report for Jul 80-Jun 81

    SciTech Connect

    Holland, A.F.; Hiegel, M.H.; Fisher, K.; Hoffman, H.; Johnson, G.F.

    1982-04-01

    This volume contains the following appendices: summary of physical/chemical and sediment data collected between July 1980 and June 1981; Summaries of benthic community data for Calvert Cliffs and Morgantown long-term benthic studies; Summary of biomass data collected between July and December 1980; Summary of size-class distribution data collected for numerically dominant bivalves; and Summary of results of stepwise regression analysis.

  6. Detailed Ar-Ar Geochronology of Volcanism at Minna Bluff, Antarctica: Two-Phased Growth and Influence on Ross Ice Shelf

    NASA Astrophysics Data System (ADS)

    Ross, J. I.; McIntosh, W. C.; Wilch, T. I.

    2012-12-01

    Minna Bluff has been a significant topographic barrier to the flow of the Ross Ice Shelf since the mid-Miocene. Detailed Ar-Ar analyses of kaersutite and sanidine phenocrysts, and groundmass concentrates from volcanic units indicate an overall west to east progression of volcanic activity. Eruptions of basaltic to intermediate lavas, domes, and scoria cones started at ~12 Ma in at what is now the eastern most point of Minna Bluff, "Minna Hook." Activity was centered in this area for ~4 Ma, constructing a pre-Minna Bluff island. Multiple glacial unconformities found at Minna Hook suggest repeated interaction with large warm-based, erosive ice sheets. Activity migrated westward from Minna Bluff Island at 7-8 Ma closing the gap created by the island and the mainland. Significant edifice construction continued until 4-5 Ma with sporadic and parasitic scoria cone eruptions, possibly associated with Mt. Discovery activity, continuing until 2 Ma. The orientations of Minna Bluff's two major axes are strongly controlled by regional tectonic features. Minna Bluff's E-W axis, McIntosh Cliffs, is sub-parallel to the Radial Lineament and the N-S axis, Minna Hook, appears as extension of faulting bounding the Terror Rift. The constructional evolution of the 70km long volcanic complex has an important role in interpreting the climate signals recovered by the ANDRILL Project. Minna Bluff influenced the material delivered to the AND-1B drill site (ANDRILL MIS 2006-2007) in three critical ways: 1) Minna Bluff diverted upstream material, 2) provided a pinning and stabilizing point for the Ross Ice Shelf, possible controlling the calving line prior to the emergence of Ross Island, and 3) was a significant source of fresh volcanic material throughout much of the period recovered by ANDRILL MIS. For example, a kaersutite-bearing clast recovered from 822.78 mbsf in AND-1B yielded an age of 8.53±0.51 Ma, and was likely derived from Minna Bluff. The results from this study can be incorporated into detailed glacier and ice-sheet models of the McMurdo Sound region, a critical area in the Ross Ice Sheet and global climate system.

  7. Paleomagnetic and 40Ar/39Ar results from the Grant intrusive breccia and coparison to the Permian Downeys Bluff Sill; evidence for Permian igneous activity at Hicks Dome, southern Illinois Basin

    USGS Publications Warehouse

    Reynolds, Richard L.; Goldhaber, Martin B.; Snee, Lawrence W.

    1997-01-01

    Igneous processes at Hicks dome, a structural upwarp at lat 37.5 degrees N., long 88.4 degrees W. in the southern part of the Illinois Basin, may have thermally affected regional basinal fluid flow and may have provided fluorine for the formation of the Illinois-Kentucky Fluorspar district. The timing of both igneous activity and mineralization is poorly known. For this reason, we have dated an intrusive breccia at Hicks dome, the Grant intrusion, using 40Ar/39Ar geochronometric and paleomagnetic methods. Concordant plateau dates, giving Permian ages, were obtained from amphibole (272.1+or-0.7 [1 sigma] Ma) and phlogopite (272.7+or-0.7 [1 sigma] Ma). After alternating-field (AF) demagnetization, specimens that contain titanomagnetite-bearing igneous rock fragments give a mean remanent direction of declination (D)=168.4 degrees; inclination (I)=-8 degrees; alpha 95=8.6 degrees; number of specimens (N)=10; this direction yields a virtual geomagnetic pole (VGP) at lat 54.8 degrees N., long 119.0 degrees E., delta p=4.4 degrees, delta m=8.7 degrees, near the late Paleozoic part of the North American apparent pole wander path. A nearly identical magnetization was found for the nearby Downeys Bluff sill (previously dated at about 275+or-24 Ma by the Rb-Sr method), in southern Illinois. Both AF and thermal demagnetization isolated shallow, southeasterly remanent directions carried by magnetite in the sill and from pyrrhotite in the baked contact of the Upper Mississippian Downeys Bluff Limestone: D=158.6 degrees; I=-11.8 degrees; alpha 95=3.8 degrees; N=15, yielding a VGP at lat 53.0 degrees N., long 128.7 degrees E., delta p=2.0 degrees, delta m=3.9 degrees. The paleomagnetic results, isotopic dates, and petrographic evidence thus favor the acquisition of thermal remanent magnetization by the Grant breccia and the Downeys Bluff sill during the Permian. The isotopic dates record rapid cooling from temperatures greater than 550 degrees C to less than 300 degrees C (the closure temperatures for diffusion of 40Ar in amphibole and phlogopite, respectively) after emplacement during the Permian. The results further indicate that individual clasts of the Grant breccia were emplaced at temperatures greater than about 550 degrees C, the magnetization-blocking temperature of the titanomagnetite in the breccia, and that it cooled very rapidly,within less than 1-2 m.y. After cooling, the breccia was not affected by thermal perturbations greater than about 300 degrees C.

  8. Blowoff behavior of bluff body stabilized flames in vitiated and partially premixed flows

    NASA Astrophysics Data System (ADS)

    Tuttle, Steven G.

    Turbulent flame holding and blowoff characteristics of bluff body stabilized flames were measured in an enclosed rectangular duct with a triangular flame holder in vitiated, premixed and unvitiated, asymmetrically stratified flows. Blowoff stability margins were characterized, with chemiluminescence measurements performed by high-speed imaging to capture flame dynamics during blow off. As the equivalence ratio was decreased, local extinction along the shear layer flames occurred with greater frequency and proximity to the wake stagnation zone. Decreased equivalence ratio resulted in extinction events at the trailing edge of the stagnation zone, where reactants were convected into the recirculation zone and burned. Eventually, increasing reactant dilution of the recirculation zone either increased the ignition time scale or the lowered the strain tolerance of the propagating flames in the flame anchoring region, resulting in lift-off or extinction, and the near field shear layer flames convected to the wake stagnation zone, where they continued to propagate. From there, the flames were convected upstream into the recirculation zone, where they were eventually quenched. Simultaneous PIV and OH PLIF measurements captured the flame edge location and aerodynamic behavior as blowoff was approached. Two-dimensional hydrodynamic stretch alone the flame front and flow field vorticity maps were extracted from the combined PIV/OH PLIF data. The distribution of flame stretch shifted to greater values as the equivalence ratio decreased. Asymmetric fuel distributions, measured with acetone LW, were found to increase the equivalence ratio at blow off from that found with uniformly-fueled flows. This was attributed to the greater wake instability and extinction of the lean-side flames. The asymmetrically fueled flames were more susceptible to thermoacoustic instabilities when the shedding frequency was near an acoustic eigenmode of the exhaust duct, due to the decreased attenuation of the Benard-Von Karman vortex shedding instability on the lean side of the wake.

  9. On the flame-generated vorticity dynamics of bluff-body stabilized premixed flames

    NASA Astrophysics Data System (ADS)

    Caramella, Lucia

    This investigation considers the dynamics of the flame-generated vorticity for a premixed, submerged bluff-body stabilized flame. Digital particle image velocimetry (DPIV) is used to obtain mean and instantaneous velocity and vorticity fields in four streamwise locations, capturing nearly the entire combustion chamber. The Mie scattering images which are collected for DPIV prove useful in determining the approximate location of the flame as indicated by a stark difference in seeding particle density caused by volumetric expansion. Examining the location of the flame fronts in relation to the mean velocity, mean vorticity, and corresponding instantaneous fields provides useful information about the interaction of the flame and the flow. Experiments characterize the far-field region in particular with a level of detail not previously afforded to this type of flow. The unique nature of the velocity and vorticity fields, as well as a change in rotation of the flame structures observed in the Mie scattering images, are explained by appealing to the baroclinic generation of vorticity. The baroclinic mechanism is activated when non-parallel pressure and density gradients are present. Mean static pressure measurements at the combustion chamber wall allow inferences about the pressure field to be made. The coupling that exists among pressure, heat release, and baroclinic generation is also acknowledged and will influence strategies for control of the baroclinic mechanism. Particular details of the coupling remain unclear, nevertheless improved understanding can lead to advancements in combustion efficiency. Simple scaling of the problem allows a prediction of baroclinic vorticity generation to be obtained. Further insight into the dynamics in the region of interest are provided using CH* filtered and unfiltered chemiluminescence images.

  10. Drag reduction on a rectangular bluff body with base flaps and fluidic oscillators

    NASA Astrophysics Data System (ADS)

    Schmidt, H.-J.; Woszidlo, R.; Nayeri, C. N.; Paschereit, C. O.

    2015-07-01

    The present paper investigates drag reduction on a rectangular bluff body by employing base flaps and controlling flow separation with fluidic oscillators. Wind tunnel experiments are conducted to assess the influence of various parameters. The flap length has to be sufficiently long to shift the wake structures far enough downstream away from the base plate. Any additional increase in flap length does not yield any further benefits. The flap angle has to be large enough to provide a sufficient inward deflection of the outer flow. If the angle is too large, actuation becomes inefficient due to the pressure gradient imposed by the opposite side of the base perimeter. Furthermore, the flaps at high deflection angles provide additional area for low pressure to act in the streamwise direction and therefore negate the positive effects of actuation. The required actuation intensity is best governed by the ratio between jet and freestream velocity for varying oscillator spacing. For a flap angle of 20°, the smallest net drag is obtained at a velocity ratio of 4.5. Furthermore, the optimal velocity ratio for the most efficient drag reduction changes linearly with flap angle. Smaller flap deflections require a smaller velocity ratio for optimal control at different oscillator spacing. A net drag reduction of about 13 % is measured at a flap angle of 20° when the drag is corrected by the momentum input. Even if the measured drag is conservatively corrected by the energy coefficient, a net improvement of 7 % is achieved. For the current setup, the most efficient drag reduction is still obtained at smaller flap angles with a lower momentum input. However, the presented results support the general feasibility of this drag reduction approach with significant room left for optimization.

  11. Evidence for Complex Mixing Processes Controlling the Composition of a Wide Range of Alkaline Volcanic Rocks at Minna Bluff, Antarctica.

    NASA Astrophysics Data System (ADS)

    Dunbar, N. W.; Panter, K.; Scanlan, M. K.; Fargo, A.; McIntosh, W. C.; Wilch, T. I.

    2008-12-01

    Minna Bluff, a 45-km-long chain of coalesced volcanic centers formed by a wide range of alkaline magmatic compositions. Compositions between basanite and phonolite are represented and these form volcanic features ranging from small, primitive, cinder cones to large, evolved domes. Abundant stacked lava flows (subaerial to subglacial), feeder dikes, and vent complexes are exposed in cliffs up to ~1000 m in height. A notable field feature of many of the volcanic rocks at Minna Bluff is the presence of large (up to 5 cm) amphibole and feldspar megacrysts, which are found in rocks of a range of compositions and eruptive styles. Microprobe analysis shows that many lavas exhibit strikingly common disequilibrium textures, consisting primarily of phenocrystic kaersutitic to ferro-kaersutitic amphibole that is either partially, or fully, broken down to a combination of plagioclase, pyroxene and magnetite. The extent to which breakdown has occurred varies from crystal to crystal. In some cases, a breakdown rim of only a few 10s of microns thickness is present, whereas in other parts of the sample, mm-scale kaersutites are almost completely reacted. Although individual phenocrysts are compositionally uniform, a range of kaersutite compositions are present (even within a single sample) with FeO and MgO contents between 9.5-18 and 7.5-13.5 wt. percent respectively. Approximately the same compositional range of kaersutite (as well as the same disequilibrium textures) is observed in samples with a range of bulk compositions. Some of the same samples contain feldspar phenocrysts with relatively evolved plagioclase (andesine) cores and more primitive (labradorite) rims. Amphibole-related disequilibrium textures are observed in basanitic lavas containing olivine with Mg- rich cores (Fo87). The textural and compositional characteristics of the Minna Bluff volcanic rocks suggest that, for many, mixing between one or more magmatic sources, shortly before the eruption process, controls the final bulk magmatic composition. Two possible mixing endmembers would be a hydrous, evolved, kaersutite-rich magma and a second, hotter, more primitive melt, and the relative abundance of the two endmembers may influence the final composition of erupted lava. These observations suggest that the mixing processes outlined by Scanlan et al., (this volume) for a single example of inclusion-rich lava at Minna Bluff may be important over a much larger part of the volcanic complex.

  12. Laboratory measurements of selected optical, physical, chemical, and remote-sensing properties of five water mixtures containing Calvert clay and a nonfluorescing dye

    NASA Technical Reports Server (NTRS)

    Usry, J. W.; Whitlock, C. H.; Poole, L. R.; Witte, W. G., Jr.

    1981-01-01

    Total suspended solids concentrations ranged from 6.1 ppm to 24.3 ppm and sizes ranged between 1.5 micrometers and 10 micrometers with the most frequently occurring size less than 2 micrometers. Iron concentration was less than 1 percent of the total suspended solids. Nonfluorescing dye concentrations of the two mixtures were 20 ppm and 40 ppm. Attenuation coefficient for the five mixtures ranged from 4.8/m to 21.3/m. Variations in volume scattering function with phase angle were typical. Variations in attenuation and absorption coefficient with wavelength were similar for the mixtures without the dye. Attenuation coefficient of the mixtures with the dye increased for wavelengths less than 600 nm due to the dye's strong absorption peak near 500 nm. Reflectance increased as the concentration of Calvert clay increased and peaked near 600 nm. The nonfluorescent dye decreased the magnitude of the peak, but had practically no effect on the variation for wavelengths greater than 640 nm. At wavelengths less than 600 nm, the spectral variations of the mixtures with the dye were significantly different from those mixtures without the dye.

  13. Calvert Cliffs Nuclear Power Plant Life Cycle Management/License Renewal Program: Structure scoping and aging management review; Volume 3. Final report

    SciTech Connect

    Doroshuk, B.W.; Tilden, B.M.; Tucker, R.L.; Hostetler, D.R.

    1995-10-01

    Central to the Life Cycle Management (LCM) Program for the Calvert Cliffs Nuclear Power Plant (CCNPP) plant is its Integrated Plant Assessment (IPA) process. The IPA is a comprehensive, systematic evaluation of the effectiveness of age-related degradation management for the plant`s important systems, structures, and components. The first set of steps in the IPA process, scoping, (called screening in earlier versions of the LR rule), identifies systems, structures, and components that are within the scope of license renewal. The second and third steps in the IPA process cover the identification of passive long-lived components requiring aging management reviews and the performance of aging management reviews for those components. This report, which is another in the CCNPP LCM series of EPRI reports, describes the methodology for performing scoping and component aging management reviews for structures. A review of the CCNPP processes will assist other nuclear power plant operators in establishing their own LCM programs. Volume 3 contains appendix F. Structural component aging management review for intake structures and auxiliary building structures.

  14. Transfer function characteristics of bluff-body stabilized, conical V-shaped premixed turbulent propane-air flames

    SciTech Connect

    Chaparro, Andres; Landry, Eric; Cetegen, Baki M.

    2006-04-15

    The response of bluff-body stabilized conical V-shaped premixed flames to periodic upstream velocity oscillations was characterized as a function of oscillation frequency, mean flow velocity, and equivalence ratio. The flame heat release response to the imposed velocity oscillations was determined from the CH* chemiluminescence captured by two photomultiplier (PMT) detectors at a wavelength of 430 nm. One of the PMTs viewed flame radiation in a 10-mm horizontal slice, 50 mm above the bluff-body. The second PMT observed the overall flame radiation. The flame transfer function characteristics were determined from the spectral analysis of the velocity and PMT signals. It was found that the flame heat release amplitude response is confined to low-frequency excitation below a Strouhal number of 4. The phase relationship of the transfer function for these turbulent flames was evaluated using the signal from the spatially masked PMT. The transfer function estimate based on these data exhibits second-order characteristics with a phase lag between the velocity and heat release signals. The localized heat-release response contains frequencies that are multiples of the excitation frequency, suggesting splitting and tilting of flame structures as well as some nonlinear effects. Increase of flame equivalence ratio from lean toward stoichiometric resulted in slight amplification of the high-frequency response. (author)

  15. Environmental Assessment of the Gering-Stegall 115-kV Transmission Line Consolidation Project, Scotts Bluff County, Nebraska

    SciTech Connect

    1995-05-01

    The Department of Energy (DOE), Western Area Power Administration (Western) proposes to consolidate segments of two transmission lines near the Gering Substation in Gering, Nebraska. The transmission lines are both located in Scotts Bluff County, Nebraska. The transmission lines are both located in Scotts Bluff County, Nebraska, within the city of Gering. Presently, there are three parallel 115-kilovolt (kV) transmission lines on separate rights-of-way (ROW) that terminate at the Gering Substation. The project would include dismantling the Archer-Gering wood-pole transmission line and rebuilding the remaining two lines on single-pole steel double circuit structures. The project would consolidate the Gering-Stegall North and Gering-Stegall South 115-kV transmission lines on to one ROW for a 1.33-mile segment between the Gering Substation and a point west of the Gering Landfill. All existing wood-pole H-frame structures would be removed, and the Gering-Stegall North and South ROWs abandoned. Western is responsible for the design, construction, operation, and maintenance of the line. Western prepared an environmental assessment (EA) that analyzed the potential environmental impacts of the proposed construction, operation, and maintenance of the 115-kV transmission line consolidation. Based on the analyses in the EA, the DOE finds that the proposed action is not a major Federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act of 1969 (NEPA).

  16. Modeling 3-D Slope Stability of Coastal Bluffs Using 3-D Ground-Water Flow, Southwestern Seattle, Washington

    USGS Publications Warehouse

    Brien, Dianne L.; Reid, Mark E.

    2007-01-01

    Landslides are a common problem on coastal bluffs throughout the world. Along the coastal bluffs of the Puget Sound in Seattle, Washington, landslides range from small, shallow failures to large, deep-seated landslides. Landslides of all types can pose hazards to human lives and property, but deep-seated landslides are of significant concern because their large areal extent can cause extensive property damage. Although many geomorphic processes shape the coastal bluffs of Seattle, we focus on large (greater than 3,000 m3), deepseated, rotational landslides that occur on the steep bluffs along Puget Sound. Many of these larger failures occur in advance outwash deposits of the Vashon Drift (Qva); some failures extend into the underlying Lawton Clay Member of the Vashon Drift (Qvlc). The slope stability of coastal bluffs is controlled by the interplay of three-dimensional (3-D) variations in gravitational stress, strength, and pore-water pressure. We assess 3-D slope-stability using SCOOPS (Reid and others, 2000), a computer program that allows us to search a high-resolution digital-elevation model (DEM) to quantify the relative stability of all parts of the landscape by computing the stability and volume of thousands of potential spherical failures. SCOOPS incorporates topography, 3-D strength variations, and 3-D pore pressures. Initially, we use our 3-D analysis methods to examine the effects of topography and geology by using heterogeneous material properties, as defined by stratigraphy, without pore pressures. In this scenario, the least-stable areas are located on the steepest slopes, commonly in Qva or Qvlc. However, these locations do not agree well with observations of deep-seated landslides. Historically, both shallow colluvial landslides and deep-seated landslides have been observed near the contact between Qva and Qvlc, and commonly occur in Qva. The low hydraulic conductivity of Qvlc impedes ground-water flow, resulting in elevated pore pressures at the base of Qva, thereby increasing the potential for landslides. Our analysis simulates the ground-water flow using the results of a 3-D ground-water flow model, MODFLOW-2000 (Harbaugh and others, 2000), to generate a 3-D pore-pressure field. Areas of elevated pore pressure reflect the influence of a perched ground-water table in Qva, as well as ground-water convergence in the coastal re-entrants. We obtain a realistic model of deep-seated landsliding by combining 3-D pore pressures with heterogeneous strength properties. The results show the least-stable areas where pore pressures are locally elevated in Qva. We compare our results with records of past landslides. The predicted leaststable areas include two historically active deep-seated landslides and areas adjacent to these landslides.

  17. Preliminary results of hydrologic testing the Middle Sentinel Bluffs Basalt Vesicular Zone at Borehole RRL-2 (3,057--3,172 feet)

    SciTech Connect

    Strait, S.R.; Spane, F.A. Jr.

    1982-12-01

    This report presents preliminary results and description of hydrologic test activities for the Middle Sentinel Bluffs Basalt Vesicular Zone at Borehole RRL-2 over the depth interval 3,057 to 3,172 feet. Hydrologic tests conducted include an over-pressure pulse test and constant head injection test. 3 refs., 6 figs., 2 tabs.

  18. Preliminary results of hydraulic testing the Middle Sentinel Bluffs basalt colonnade/entablature at Borehole RRL-2 (3,175-3,244 feet)

    SciTech Connect

    Strait, S.R.; Spane, F.A. Jr.

    1982-11-01

    This report presents preliminary results and description of hydraulic test activities for a section of Middle Sentinel Bluffs basalt colonnade/entablature at borehole RRL-2 over the depth interval 3,175 to 3,244 feet. Hydrologic tests conducted include a four step constant head injection test and one over-pressure pulse test. 6 refs., 7 figs., 3 tabs.

  19. Large eddy simulation of bluff body stabilized premixed and partially premixed combustion

    NASA Astrophysics Data System (ADS)

    Porumbel, Ionut

    Large Eddy Simulation (LES) of bluff body stabilized premixed and partially premixed combustion close to the flammability limit is carried out in this thesis. The main goal of the thesis is the study of the equivalence ratio effect on flame stability and dynamics in premixed and partially premixed flames. An LES numerical algorithm able to handle the entire range of combustion regimes and equivalence ratios is developed for this purpose. The algorithm has no ad-hoc adjustable model parameters and is able to respond automatically to variations in the inflow conditions, without user intervention. Algorithm validation is achieved by conducting LES of reactive and non-reactive flow. Comparison with experimental data shows good agreement for both mean and unsteady flow properties. In the reactive flow, two scalar closure models, Eddy Break-Up (EBULES) and Linear Eddy Mixing (LEMLES), are used and compared. Over important regions, the flame lies in the Broken Reaction Zone regime. Here, the EBU model assumptions fail. In LEMLES, the reaction-diffusion equation is not filtered, but resolved on a linear domain and the model maintains validity. The flame thickness predicted by LEMLES is smaller and the flame is faster to respond to turbulent fluctuations, resulting in a more significant wrinkling of the flame surface when compared to EBULES. As a result, LEMLES captures better the subtle effects of the flame-turbulence interaction, the flame structure shows higher complexity, and the far field spreading of the wake is closer to the experimental observations. Three premixed (? = 0.6, 0.65, and 0.75) cases are simulated. As expected, for the leaner case (? = 0.6) the flame temperature is lower, the heat release is reduced and vorticity is stronger. As a result, the flame in this case is found to be unstable. In the rich case (? = 0.75), the flame temperature is higher, and the spreading rate of the wake is increased due to the higher amount of heat release. The ignition delay in the lean case (? = 0.6) is larger when compared to the rich case (? = 0.75), in correlation with the instantaneous flame stretch. Partially premixed combustion is simulated for cases where the transverse profile of the inflow equivalence ratio is variable. The simulations show that for mixtures leaner in the core the vortical pattern tends towards anti-symmetry and the heat release decreases, resulting also in instability of the flame. For mixtures richer in the core, the flame displays sinusoidal flapping that results in larger wake spreading. The numerical simulations presented in this study employed simple, one-step chemical mechanisms. More accurate predictions of flame stability will require the use of detailed chemistry, raising the computational cost of the simulation. To address this issue, a novel algorithm for training Artificial Neural Networks (ANN) for prediction of the chemical source terms has been implemented and tested. Compared to earlier methods, such as reaction rate tabulation, the main advantages of the ANN method are in CPU time and disk space and memory reduction. The results of the testing indicate reasonable algorithm accuracy although some regions of the flame exhibit relatively significant differences compared to direct integration.

  20. Vortex dynamics and scalar transport in the wake of a bluff body driven through a steady recirculating flow

    NASA Astrophysics Data System (ADS)

    Poussou, Stephane B.; Plesniak, Michael W.

    2012-09-01

    The air ventilation system in wide-body aircraft cabins provides passengers with a healthy breathing environment. In recent years, the increase in global air traffic has amplified contamination risks by airborne flu-like diseases and terrorist threats involving the onboard release of noxious materials. In particular, passengers moving through a ventilated cabin may transport infectious pathogens in their wake. This paper presents an experimental investigation of the wake produced by a bluff body driven through a steady recirculating flow. Data were obtained in a water facility using particle image velocimetry and planar laser induced fluorescence. Ventilation attenuated the downward convection of counter-rotating vortices produced near the free-end corners of the body and decoupled the downwash mechanism from forward entrainment, creating stagnant contaminant regions.

  1. An Experimental Study on Base Pressure Correction for Bluff-Base Bodies Using Magnetic Suspension and Balance System

    NASA Astrophysics Data System (ADS)

    Tadakuma, Kenji; Aso, Shigeru; Tani, Yasuhiro; Mizoguchi, Yasushi; Okada, Takumi

    An experimental study on validity and improvement of base pressure correction for a bluff-base body with hemisphere nose using MSBS (Magnetic Suspension and Balance System) has been conducted. Force and pressure distribution data on the model base were examined for several parameters; angles of attack 0 7.5, Reynolds number ReD=7.6104, with or without a sting and diameters of the sting. These results showed that the base pressure correction using the pressure data near the sting could have validity at the case of 0 of angle of attack only. Besides we could propose a new accurate method to calculate base-pressure axis forces.

  2. Preliminary results of hydrologic testing the Middle Sentinel Bluffs flow-top at borehole RRL-2 (2981 - 3020 feet)

    SciTech Connect

    Strait, S.R.; Spane, F.A. Jr.

    1983-01-01

    This report presents preliminary results and description of hydrologic testing activities for the Middle Sentinel Bluffs flow top (2,981-3,020 feet) at Borehole RRL-2. Hydrologic tests conducted include four over-pressure pulse, one constant head injection, and one slug injection test. Preliminary results indicate an observed hydraulic head for the test interval of 398.8 feet above mean sea level. Transmissivity values determined from hydrologic tests performed range between 9.3 {times} 10{sup {minus}3} to 6.2 {times} 10{sup {minus} 2} ft{sup 2}/day, with an assigned best estimate of 4.2 {times} 10{sup {minus}2} ft{sup 2}/day. The best estimate of equivalent hydraulic conductivity, based on an effective test thickness of 19 feet, is 2.2 {times} 10{sup {minus}3} ft/day. 8 refs., 10 figs., 4 tabs.

  3. Reconnaissance of Acid Drainage Sources and Preliminary Evaluation of Remedial Alternatives at the Copper Bluff Mine, Hoopa Valley Reservation, California

    USGS Publications Warehouse

    Alpers, Charles N.; Hunerlach, Michael P.; Hamlin, Scott N.; Zierenberg, Robert A.

    2003-01-01

    Acidic drainage from the inactive Copper Bluff mine cascades down a steep embankment into the Trinity River, on the Hoopa Valley Reservation in northern California. The Copper Bluff mine produced about 100,000 tons of sulfide-bearing copper-zinc-gold-silver ore during 1957?1962. This report summarizes the results of a water-resources investigation begun by the U.S. Geological Survey in 1994 with the overall objective of gathering sufficient geochemical, hydrologic, and geologic information so that a sound remediation strategy for the Copper Bluff mine could be selected and implemented by the Hoopa Valley Tribe. This study had the following specific objectives: (1) monitor the quality and quantity of the mine discharge, (2) determine seasonal variability of metal concentrations and loads, (3) map and sample the underground mine workings to determine sources of flow and suitability of mine plugging options, and (4) analyze the likely consequences of various remediation and treatment options. Analysis of weekly water samples of adit discharge over parts of two wet seasons (January to July 1995 and October 1995 to May 1996) shows that dissolved copper (Cu) and zinc (Zn) concentrations (in samples filtered with 0.20-micrometer membranes) varied systematically in a seasonal pattern. Metal concentrations increased dramatically in response to the first increase in discharge, or first flush, early in the wet season. The value of Zn/Cu in the adit discharge exhibited systematic seasonal variations; an annual Zn/Cu cycle was observed, beginning with values between 3 and 5 during the main part of the wet season, rising to values between 6 and 10 during the period of lowest discharge late in the dry season, and then dropping dramatically to values less than 3 during the first-flush period. Values of pH were fairly constant in the range of 3.1 to 3.8 throughout the wet season and into the beginning of the dry season, but rose to values between 4.5 and 5.6 during the period of lowest discharge, from October to early December 1995. Underground reconnaissance was conducted once during dry-season conditions (September 1995) and twice during wet-season conditions (March 1995 and March 1996). The main tunnel was accessed to a distance of about 600 feet from the portal entrance. Water samples were collected at nine locations along the floor of the main tunnel and from several ore shoots to evaluate the contributions of water and dissolved constituents from different portions of the mine. Values of pH ranged from 2.5 to 6.4 at different underground locations, concentrations of copper ranged from 0.020 to 44 mg/L (milligram per liter), zinc from 6.3 to 160 mg/L, and cadmium from 0.010 to 0.47 mg/L. Discharge from the ore shoots ranged from less than 1 gallon per minute to more than 30 gallons per minute and was always a small component of the total mine flow compared with the tunnel floor drainage. During March 1996, the main flow originated in the northernmost portion of the underground workings (inaccessible) and mixed with an unknown quantity of water upwelling from flooded lower workings. High-water marks observed on the tunnel walls indicate that past blockages impounded more than 100,000 gallons of water. Sudden release of a large volume of metal-rich water could have serious effects on fish and other aquatic resources in the Trinity River. Because of the hydrogeologic setting, mine plugging is not likely to offer an effective long-term solution to the problem of acid mine drainage at the Copper Bluff mine. The underground workings are close to a state highway and underlie a 500-foot-high bluff with highly fractured rocks that seep during the wet season. Total plugging likely would result in additional uncontrolled seepage and could potentially destabilize the highway. Partial plugging to restrict flow during periods of highest discharge may provide benefits in terms of reduced risk of catastrophic release without the addi

  4. Technology resource document for the assembled chemical weapons assessment environmental impact statement. Vol. 3 : assembled systems for weapons destruction at Pine Bluff Arsenal.

    SciTech Connect

    Kimmell, T.; Folga, S., Frey, G.; Molberg, J.; Kier, P.; Templin, B.; Goldberg, M.

    2001-05-04

    This volume of the Technical Resource Document (TRD) for the Environmental Impact Statement (EIS) for the ''Design, Construction and Operation of One or More Pilot Test Facilities for Assembled Chemical Weapons Destruction Technologies at One or More Sites'' (PMACWA 2001g) pertains to the destruction of assembled chemical weapons (ACW) stored in the U.S. Army's unitary chemical stockpile at Pine Bluff Arsenal (PBA), located outside Pine Bluff, Arkansas. This volume presents technical and process information on each of the destruction technologies applicable to treatment of the specific ACW stored at PBA. The destruction technologies described are those that have been demonstrated as part of the Assembled Chemical Weapons Assessment (ACWA) selection process (see Volume 1).

  5. Analysis of river planforms in the New Madrid region and possible relations to tectonic warping across the loess bluffs and within the meander belt of the Mississippi River

    SciTech Connect

    Johnson, K.A.; Mayer, L. . Dept. of Geology)

    1993-03-01

    Stream channel planforms measured from such streams as the Hatchie (H), L'Anguille (LA), St. Francis, White (W) and Little Red (LR) rivers provide a way to study influences of topographic warping between the loess bluffs that bound the Mississippi river valley. Planforms are analyzed using sinuosity, Richardson analysis, and pattern. Pattern changes include transitions from braided to meandering and meandering to straight. Sinuosities of the W and LR rivers show a transition from low sinuosity, [1.3, 1.4] to higher sinuosity [2.6, 2.8], over a short distance, as they cross the bluffs from the uplands to the Western Lowlands. On the east, the Hatchie changes from a braided to meandering pattern upon crossing the bluffs. Its sinuosity varies from a low of about 1.4 to a high of 2.2, coincident with a marsh area. The LA river flows on the west side of Crowley's Ridge and is paralleled by the St. Francis river on the east. These rivers, with very different drainage areas and sinuosities, show matching meander bends at similar wavelengths along Crowley's Ridge. The bends are about 10 km in 1/2 wavelength suggesting some extraordinary influence on pattern perpendicular to the ridge. Richardson analysis indicates that features with a 1/2 wavelength of 2 km may control several rivers' bending patterns. These features are analyzed to determine their spatial relations with one another.

  6. A revision of Metaleptobasis Calvert (Odonata:Coenagrionidae) with seven synonymies and the description of eighteen new species from South America.

    PubMed

    Von Ellenrieder, Natalia

    2013-01-01

    Examination of over 1,400 specimens of the neotropical genus Metaleptobasis Calvert, 1907, including primary types or paratypes of 18 of the 20 currently available species names and large series of specimens including pairs in tandem and copula, allowed me to unequivocally associate older names with species, distinguish between specific and intraspecific variability, associate both sexes for each species, and recognize the existence of female polymorphism. As a result, seven names are found to be junior synonyms: Metaleptobasis mauritia Williamson, 1915 junior synonym of M. bicornis (Selys, 1877), M. manicaria Williamson, 1915 and M. fernandezi Rcenis, 1955 junior synonyms of M. diceras (Selys, 1877), M. westfalli Cumming, 1954 junior synonym of M. foreli Ris, 1915, and M. tetragena Calvert, 1947, M. weibezahni Rcenis, 1955, and M. incisula De Marmels, 1989 junior synonyms of M. brysonima Williamson, 1915. Lectotypes are designated for M. amazonica and Leptobasis diceras. Eighteen new species of Metaleptobasis are described: M. brevicauda (Holotype ?, Peru, Hunuco Dep., Shapajilla, jungle, 11 v 1939, F. Woytkowski leg., in UMMZ); M. falcifera (Holotype ?, Peru, Madre De Dios Dep., Pakitza, Reserved Zone, Manu National Park, T2 to R2 to T1 to base camp, 1155'48''S, 7115'18''W, 250 m, 17 ix 1989, J.A. Louton leg., in USNM); M. furcifera (Holotype ?, Peru, Loreto Dep., Iquitos, iii 1936, G.G. Klug leg., in BMNH); M. gabrielae (Holotype ?, Peru, Loreto Dep., Tamshiyacu-Tahuayo Reserve, forest interior (423'40''S, 7314'56''W), 27 vii 2009, T. Faasen leg., in RMNH); M. guillermoi (Holotype ?, Peru, Loreto Dep., Yarinacocha, temporary forest stream (817'S, 7437'W, 145 m), 2 vi 1972, D.L. Pearson leg., in FSCA); M. inermis (Holotype ?, Brazil, Par State, Jacareacanga, vii 1969, F.R. Barbosa leg., in UMMZ); M. leniloba (Holotype ?, Peru, Loreto Dep., Pacaya-Samiria National Reserve, Santa Luisa trail (515'S, 7440'W), 10 vi 2008, C. Beatty, A. Cordero & J. Hoffmann leg., in FSCA); M. longicauda (Holotype ?, Brazil, Mato Grosso State, C. Teles Pires, Alto Tapajos, 1-31 viii 1956, Sick leg., in MNRJ); M. orthogonia (Holotype ?, Peru, Loreto Dep., San Juan, Ro Amazonas, near Iquitos, viii 1939, J. Schunke leg., in FSCA); M. paludicola (Holotype ?, Peru, Loreto Dep., Tamshiyacu-Tahuayo Reserve, swamp, 423'49''S, 7314'57''W, 27 ii 2009, T. Faasen leg., in RMNH); M. panguanae (Holotype ?, Peru, Hunuco Dep., Biological Station Panguana, E side Ro Yuyapichis, 937'S, 7457'W, 6-17 iv 2003, H.J. & E.-G. Burmeister leg., in ZSM); M. peltata (Holotype ?, Peru Loreto Dep., Tamshiyacu-Tahuayo Reserve, 421'22''S, 7311'0''W, 19 ii 2010, T. Faasen leg., in RMNH); M. prostrata (Holotype ?, Peru, Junn Dep., Satipo, v 1945, P. Paprzycki leg., in UMMZ); M. silvicola (Holotype ?, Peru, Madre de Dios Dep., Explorer's Inn on Ro Tambopata, 30 km SW Puerto Maldonado, main trail, 1 viii 1979, M. Perkins & P. Donahue leg., in FSCA); M. spatulata (Holotype ?, Peru, Hunuco Dep., 10 km N of Cucharas, confluence of Huallaga and Pacay rivers, viii 1954, F. Woytkowski leg., in UMMZ); M. tridentigera (Holotype ?, Brazil, Rondnia State, Porto Velho, Area Abunan, T11 Aleatorio, 846'S, 6354'W, 86 m, 16 v 2010, Nogueira & Mendes leg., in MZUSP); M. truncata (Holotype ?, Brazil, Par State, Jacareacanga, xi 1969, F.R. Barbosa leg., in UMMZ); and M. turbinata (Holotype ?, Peru, Loreto Dep., Tamshiyacu-Tahuayo Reserve, forest swamp (424'18''S, 7314'38''W), 25 ii 2010, T. Fassen leg., in RMNH). Illustrations, keys, diagnoses, and distribution maps for all 31 currently known species are provided. Phylogenetic relationships within the genus Metaleptobasis are analyzed based on 33 adult morphological characters, including the 31 currently described species of Metaleptobasis and eleven outgroup taxa of other Coenagrionidae of the subfamily Teinobasinae. The cladistic analysis recovered Metaleptobasis as monophyletic, and as sister group of Aceratobasis Kennedy, a teinobasine genus s

  7. Prediction of turbulent recirculating flow field behind a V-shaped bluff body using a nonlinear low Reynolds number k-epsilon model

    NASA Astrophysics Data System (ADS)

    Gu, Zhan

    1998-09-01

    A new localized smoothing filter based on the least squares is proposed in this study. It has been found the use of an appropriate smoothing method is critical to the success of numerical prediction of separating flow problems with nonlinear turbulence models. The new smoothing filter effectively eliminated numerical fluctuations due to the nonlineality of the turbulence model and the higher order approximation. The efficiency of using this scheme is very attractive; less than 20% more CPU time is needed for the extra computation in simulations. Modification has been made to the nonlinear model to take into consideration of low Reynolds number effects. The two-dimensional turbulent recirculating flow field behind a V-shaped bluff body has been investigated numerically. Similar bluff bodies are used in combustion chambers for flame stabilization. The study helps to gain a comprehensive understanding of the mechanism of the flame stability and major factors that affect this stability, and thereby establishes a more reasonable physical model. The validation test of turbulent flow over a backward facing step shows that the modified nonlinear turbulence model significantly improved the overall prediction. Predicted results for both mean flow field and turbulence quantities agreed very well experimental results. The prediction error for the characteristic reattachment length has been reduced from 18% to 4% compared with the experimental data. The results of simulation of flow field behind the bluff body are also improved by using this model. The degree of improvement varies for different flow variables. Parametric investigation of the flow field by varying the shape and size of the bluff body is also performed. It has been found that the axial distributions of normalized reverse mass flow rate for different configurations are similar. The maximum reverse mass flow rate increases monotonically with the base height as well as with the included angle of the bluff body, but normalized axial location of the maximum reverse mass flow rate remains unchanged. Similarly, although the separation bubble length increases linearly rate remains unchanged. Similarly, although the separation bubble length increases linearly as the base height or included angle is increased, the normalized separation bubble length is almost the same for all cases.

  8. Monitoring of populations and productivity of seabirds at St. George Island, Cape Peirce, and Bluff, Alaska, 1989. Final report

    SciTech Connect

    Mendenhall, V.M.

    1991-04-01

    In recent years, although descriptive studies have continued, the emphasis on population monitoring of seabirds has increased. Commercial uses of the Continental Shelf of the Bering and Chukchi Seas, including oil and gas development, subsurface placer mining, and commercial fishing, carry the potential for adverse pressures on seabird populations. Populations and productivity of seabirds were monitored in 1989 at three Bering Sea colonies: St. George, Cape Peirce, and Bluff. Murres and black-legged kittiwakes were monitored at all colonies to facilitate intercolony comparisons. These species were selected because they are relatively easy to study, numerous, sensitive to potential impacts of development, and widely distributed. Red legged kittiwakes also were monitored at St. George because of concern for the world status of the species. Methods were standardized among the three colonies to facilitate comparisons among colonies and years. Observations of productivity began at the time nests were established and continued until most young had fledged. Kittiwake nests and murre breeding sites used for estimation of productivity were mapped on photographs or sketches and the fate of each was recorded.

  9. Classification of gas-liquid flow patterns by the norm entropy of wavelet decomposed pressure fluctuations across a bluff body

    NASA Astrophysics Data System (ADS)

    Sun, Zhiqiang; Chen, Yanping; Gong, Hui

    2012-12-01

    Identification of gas-liquid flow patterns remains one of the paramount needs in multiphase flow metering. It is hardly possible to realize accurate measurement and control of parameters in a gas-liquid flow system without a clear understanding of its flow pattern. Here we explore the characterization of gas-liquid flow patterns using the norm entropy extracted from the wavelet decomposed pressure fluctuations across a bluff body. Experiments on air-water two-phase flow at ambient temperature and atmospheric pressure are carried out in the bubble, plug, slug and annular flow patterns. On the basis of the experimental results, two original flow-pattern maps are constructed: one is coordinated with the average norm entropy versus the total mass flow rate, and the other is the average norm entropy versus the volumetric void fraction. Verification tests demonstrate that the overall identification rates of the flow-pattern maps developed exceed 95%. This approach provides an effective and simple solution to the classification of gas-liquid flow patterns.

  10. Tests of dynamic Lagrangian eddy viscosity models in Large Eddy Simulations of flow over three-dimensional bluff bodies

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-Heng; Meneveau, Charles; Parlange, Marc B.

    2004-11-01

    Large Eddy Simulations (LES) of atmospheric boundary-layer air movement in urban environments are especially challenging due to complex ground topography. Typically in such applications, fairly coarse grids must be used where the subgrid-scale (SGS) model is expected to play a crucial role. A LES code using pseudo-spectral discretization in horizontal planes and second-order differencing in the vertical is implemented in conjunction with the immersed boundary method to incorporate complex ground topography, with the classic equilibrium log-law boundary condition in the new-wall region, and with several versions of the eddy-viscosity model: (1) the constant-coefficient Smagorinsky model, (2) the dynamic, scale-invariant Lagrangian model, and (3) the dynamic, scale-dependent Lagrangian model. Other planar-averaged type dynamic models are not suitable because spatial averaging is not possible without directions of statistical homogeneity. These SGS models are tested in LES of flow around a square cylinder and of flow over surface-mounted cubes. Effects on the mean flow are documented and found not to be major. Dynamic Lagrangian models give a physically more realistic SGS viscosity field, and in general, the scale-dependent Lagrangian model produces larger Smagorinsky coefficient than the scale-invariant one, leading to reduced distributions of resolved rms velocities especially in the boundary layers near the bluff bodies.

  11. Blowoff characteristics of bluff-body stabilized conical premixed flames with upstream spatial mixture gradients and velocity oscillations

    SciTech Connect

    Chaudhuri, Swetaprovo; Cetegen, Baki M.

    2008-06-15

    This experimental study concerns determination of blowoff equivalence ratios for lean premixed conical flames for different mixture approach velocities ranging from 5 to 16 m/s in the presence of spatial mixture gradients and upstream velocity modulation. Conical flames were anchored on a disk-shaped bluff body that was attached to a central rod in the burner nozzle. A combustible propane-air mixture flowed through a converging axisymmetric nozzle with a concentric insert, allowing radial mixture variation by tailoring the composition in the inner and outer parts of the nozzle. The radial mixture profiles were characterized near the location of the flame holder by laser Rayleigh light scattering. Additionally, a loudspeaker at the nozzle base allowed introduction of periodic velocity oscillations with an amplitude of 9% of the mean flow velocity up to a frequency of 350 Hz. The flame blowoff equivalence ratio was experimentally determined by continuously lowering the fuel flow rates and determining the flame detachment point from the flame holder. Flame detachment was detected by a rapid reduction of CH* emission from the flame base imaged by a photomultiplier detector. It was found that the flame blowoff is preceded by progressive narrowing of the flame cone for the case of higher inner jet equivalence ratios. In this case, the fuel-lean outer flow cannot sustain combustion, and clearly this is not a good way of operating a combustor. Nevertheless, the overall blowoff equivalence ratio is reduced by inner stream fuel enrichment. A possible explanation for this behavior is given based on the radial extent of the variable-equivalence-ratio mixture burning near the flame stabilization region. Fuel enrichment in the outer flow was found to have no effect on blowoff as compared to the case of uniform mixture. The results were similar for the whole range of mean flow velocities and upstream excitation frequencies. (author)

  12. Two-stage growth of the Late Miocene Minna Bluff Volcanic Complex, Ross Embayment, Antarctica: implications for ice-sheet and volcanic histories

    NASA Astrophysics Data System (ADS)

    Wilch, T. I.; McIntosh, W. C.; Panter, K. S.; Dunbar, N. W.; Smellie, J.; Fargo, A. J.; Ross, J. I.; Antibus, J. V.; Scanlan, M. K.

    2011-12-01

    Minna Bluff, a 45km long, 5km wide Late Miocene alkaline volcanic peninsula that extends SE into the Ross Ice Shelf, is a major obstruction to ice flow from the south into the McMurdo Sound region. Interpretations of the abundant paleoclimate and glacial history archives, including the ANDRILL records, need to account for the effects of paleogeography on past ice-flow configurations and sediment transport. Mapping and 40Ar/39Ar dating of volcanic sequences indicate that Minna Bluff was constructed between 12 and 4 Ma. The volcanic complex first emerged as an isolated island in the Ross Sea at about 12 Ma. The edifice, here named Minna Hook Island, was constructed between 12 and 8 Ma. During this first stage of growth, regional ice was able to flow through a ~40 km gap between the island and mainland. The second stage of volcanism built the main arm of Minna Bluff, now called McIntosh Cliffs, between 8 and 4 Ma. The second stage resulted in the eruption of exclusively subaerial cinder cones and lava flows. By approximately 5 Ma the peninsula had fully emerged above sea level, fully obstructing ice flow. Evidence for volcano-ice interaction is common in Minna Hook stratigraphic sequences. Well exposed cliff sections exhibit alternations between rocks erupted in subaerial and subaqueous conditions; these sequences are interpreted to represent syneruptive interactions between lava flows and glacial ice and provide evidence for periodic glaciations between 12 and 8 Ma. The lack of coherent horizontal passage zones between subglacial and subaerial lithofacies and the alternating nature of the deposits suggest that the eruptions did not occur in a large stable ice sheet but instead occurred in a more ephemeral local ice cap or rapidly drained ice sheet. At least two widespread, undulating glacial unconformities mantled by glacial and fluvial sediments are exposed near the base of the Minna Hook sequences. These unconformities record broad scale Antarctic Ice Sheet events between 10.46 and 10.31 Ma and between 9.81 and 9.46 Ma. The older of these widespread glaciations may correspond to Miocene Isotope Event 6 (Mi6), identified in marine sediment records. Eruptions and glacial overriding events at Minna Bluff occurred over the same time interval as sedimentation at the Andrill MIS and SMS core sites.

  13. Paleoenvironment of the Ogallala (Neogene) Formation in west-central Kansas

    SciTech Connect

    Twiss, P.C.; McCahon, T.J.; Oviatt, C.G. . Geology Dept.)

    1993-02-01

    At Lake Scott (Scott County) in west-central Kansas, the Ogallala Formation unconformably overlies the Niobrara Formation (Cretaceous) and forms the bluffs of the north-trending Ladder Creek valley. Two sections (Devil's Backbone, 23 m thick; Suicide Bluff, 45 m thick) contain fluvial sands that grade upward into probable eolian sands. The lower sections contain poorly cemented, moderately sorted, arkosic sand, some mud gravel, and poorly defined fluvial channels. In the lower part of Devil's Backbone, cross-bedded sand is capped by mud drapes. At Suicide Bluff, beds of cross-bedded and better sorted sand occur high in the section. Paleosols and secondary calcite and opal dominate the sections. Pedogenic calcretes with more than 52% CaCO[sub 3] are especially abundant and range up to morphologic Stage VI. The [delta][sup 13]C and [delta][sup 18]O in the calcretes range from [minus]4.8 to [minus]6.5 and [minus]8.2 to [minus]6.7 per mil (PDB), respectively. Opal-A has replaced most rhizoliths of the Ogallala. Silicified fossil seeds (Celtis sp., Biorbia sp.) and probable fossil mammal burrows also occur in the sections. Rhyolitic tephra, about 10 Ma, occurs 12 m below the calcrete caprock of Suicide Bluff. A massive layer of opal occurs about 8 m above the tephra and below a diatomaceous bed. Siliceous cement occurs throughout each section, possibly originating from opal phytoliths, tephra, and/or diatoms. These sections afford the potential for understanding the stratigraphic succession and paleoclimate during the late Miocene to possibly early Pliocene in the central High Plains region.

  14. Interglacial Extension of the Boreal Forest Limit in the Noatak Valley, Northwest Alaska: Evidence from an Exhumed River-Cut Bluff and Debris Apron

    USGS Publications Warehouse

    Edwards, M.E.; Hamilton, T.D.; Elias, S.A.; Bigelow, N.H.; Krumhardt, A.P.

    2003-01-01

    Numerous exposures of Pleistocene sediments occur in the Noatak basin, which extends for 130 km along the Noatak River in northwestern Alaska. Nk-37, an extensive bluff exposure near the west end of the basin, contains a record of at least three glacial advances separated by interglacial and interstadial deposits. An ancient river-cut bluff and associated debris apron is exposed in profile through the central part of Nk-37. The debris apron contains a rich biotic record and represents part of an interglaciation that is probably assignable to marine-isotope stage 5. Pollen spectra from the lower part of the debris apron closely resemble modern samples taken from the Noatak floodplain in spruce gallery forest, and macrofossils of spruce are also present at this level. Fossil bark beetles and carpenter ants occur higher in the debris apron. Mutual Climatic Range (MCR) estimates from the fossil beetles suggest temperatures similar to or warmer than today. Together, these fossils indicate the presence of an interglacial spruce forest in the western part of the Noatak Basin, which lies about 80 km upstream of the modern limit of spruce forest.

  15. Computational fluid dynamic studies of certain ducted bluff-body flowfields relevant to turbojet combustors. Volume 2: Time-averaged flowfield predictions for a proposed centerbody combustor

    NASA Astrophysics Data System (ADS)

    Raju, M. S.; Krishnamurthy, L.

    1986-07-01

    The near-wake region in a ducted bluff-body combustor was investigated by finite-difference computations. The numerical predictions are based upon the time-independent, Reynolds-averaged Navier-Stokes equations and the k-epsilon turbulence model. The steady-state calculations address both nonreacting and reacting flowfields in a novel configuration to more realistically simulate some of the essential features of the primary zone of a gas turbine combustion chamber. This configuration is characterized by turbulent mixing and combustion in the recirculating near-wake region downstream of an axisymmetric bluff body due to two annular air streams--an outer swirl-free flow and an inner swirling flow--and a central fuel jet. The latter contains propane for reacting flows and carbon dioxide for nonreacting flows. In view of the large number of geometrical and flow parameters involved, the reported results are concerned with only a limited parametric examination with the major emphasis being on nonreacting flows. Questions addressed for a particular set of geometric parameters include the effects of variation of mass flow rates in all three streams and the influence of swirl in the middle stream. Reacting computations investigate the influence of swirl on combustion, as well as that of combustion on the flowfield.

  16. Aerodynamics of the flying snake Chrysopelea paradisi: how a bluff body cross-sectional shape contributes to gliding performance.

    PubMed

    Holden, Daniel; Socha, John J; Cardwell, Nicholas D; Vlachos, Pavlos P

    2014-02-01

    A prominent feature of gliding flight in snakes of the genus Chrysopelea is the unique cross-sectional shape of the body, which acts as the lifting surface in the absence of wings. When gliding, the flying snake Chrysopelea paradisi morphs its circular cross-section into a triangular shape by splaying its ribs and flattening its body in the dorsoventral axis, forming a geometry with fore-aft symmetry and a thick profile. Here, we aimed to understand the aerodynamic properties of the snake's cross-sectional shape to determine its contribution to gliding at low Reynolds numbers. We used a straight physical model in a water tunnel to isolate the effects of 2D shape, analogously to studying the profile of an airfoil of a more typical flyer. Force measurements and time-resolved (TR) digital particle image velocimetry (DPIV) were used to determine lift and drag coefficients, wake dynamics and vortex-shedding characteristics of the shape across a behaviorally relevant range of Reynolds numbers and angles of attack. The snake's cross-sectional shape produced a maximum lift coefficient of 1.9 and maximum lift-to-drag ratio of 2.7, maintained increases in lift up to 35 deg, and exhibited two distinctly different vortex-shedding modes. Within the measured Reynolds number regime (Re=3000-15,000), this geometry generated significantly larger maximum lift coefficients than many other shapes including bluff bodies, thick airfoils, symmetric airfoils and circular arc airfoils. In addition, the snake's shape exhibited a gentle stall region that maintained relatively high lift production even up to the highest angle of attack tested (60 deg). Overall, the cross-sectional geometry of the flying snake demonstrated robust aerodynamic behavior by maintaining significant lift production and near-maximum lift-to-drag ratios over a wide range of parameters. These aerodynamic characteristics help to explain how the snake can glide at steep angles and over a wide range of angles of attack, but more complex models that account for 3D effects and the dynamic movements of aerial undulation are required to fully understand the gliding performance of flying snakes. PMID:24477611

  17. It Pays To Bluff.

    ERIC Educational Resources Information Center

    Fletcher, Mike; Mooney, Claire

    2001-01-01

    Observes the application of probability theory to a game between two players. Shows how basic techniques such as tree diagrams can be used to demonstrate optimum strategies, how the art of bluffing can be quantified, and how this might be applied to a game of poker. (Author/ASK)

  18. The Knowledge Bluff

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2007-01-01

    Our knowledge "system" is built up from disciplines and specialties as its components, which are "wired" by patterns of collaboration that constitute its organization. The intellectual autonomy of these components prevents this knowledge system from adequately accounting for what we have gradually discovered during the past 50 years: In human

  19. The Knowledge Bluff

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2007-01-01

    Our knowledge "system" is built up from disciplines and specialties as its components, which are "wired" by patterns of collaboration that constitute its organization. The intellectual autonomy of these components prevents this knowledge system from adequately accounting for what we have gradually discovered during the past 50 years: In human…

  20. Water-resources appraisal of the Camp Swift lignite area, central Texas

    USGS Publications Warehouse

    Gaylord, J.L.; Slade, R.M.; Ruiz, L.M.; Welborn, C.T.; Baker, E.T.

    1985-01-01

    The Camp Swift area, Texas was studied to describe the hydrogeology and to provide baseline data of the groundwater and surface water resources that would be affected by the strip mining of lignite. The investigation was centered on the 18-square mile Camp Swift Military Reservation where a reported 80 to 100 million short tons of commercially mineable lignite occurs within 200 feet of the land surface. Groundwater data showed that water levels in observation wells changed only slightly and that the water quality in the Calvert Bluff Formation, which contains the lignite, and in the Simsboro Formation, which is the major aquifer beneath the Calvert Bluff, is suitable for most uses. Big Sandy Creek, which crosses Camp Swift generally has a base flow of less than 0.5 cu ft/sec and infrequently is dry. Dogwood Creek, which originates on Camp Swift, usually is dry. The flow of both streams changes rapidly in response to rainfall in the watersheds. The quality of the water in both streams generally is suitable for most uses. A lithologic examination of 255 feet of cored section that represents the overburden and the lignite showed cyclic layering of fine sand, silt, clay, and lignite. Chemical analyses indicate that the pyritic sulfur concentration is small but variable. (USGS)

  1. Chronostratigraphy and biostratigraphy of Paleogene Formations in eastern Gulf Coastal Province

    SciTech Connect

    Siesser, W.G.

    1985-02-01

    Paleogene formations extending from eastern Alabama to Arkansas have been assigned to internationally recognized biostratigraphic zones based on calcareous nannoplankton fossils. All zones from NP 1 to NP 24 are present in the study area, with the exception of NP 11 (within the early Eocene) and NP 23 (within the early Oligocene). Gulf Coast formations correlate to international standard chronostratigraphic stages as follows. The Clayton and Porters Creek formations correlate to the Danian Stage. The Naheola Formation, Salt Mountain Limestone, Nanafalia Formation, Tuscahoma Sand, and lower Hatchetigbee Formation (in part) correlate to the Selandian Stage. The Hatchetigbee (in part) and lower Tallahatta correlate to the Ypresian Stage; the upper Tallahatta and most of the Lisbon and Cook Mountain Formations correlate to the Lutetian Stage. The upper Lisbon and Cook Mountain formations, the Gosport Sand, Moodys Branch, and lowermost Yazoo formations correlate to the Bartonian Stage. The Crystal River and most of the Yazoo Formation correlate to the Priabonian Stage. The uppermost Yazoo Formation, the Bumpnose Limestone, Red Bluff, Forest Hill, and Mint Spring Formations, Marianna and Glendon Limestones, and Byram and Bucatunna Formations correlate to the Rupelian Stage. The Chickasawhay Limestone and Paynes Hammock Formation span the Rupelian-Chattian boundary. The Paleocene-Eocene boundary (approximately the NP 9-NP 10 boundary) is therefore within the lower Hatchetigbee Formation (Bashi Marl Member). The Eocene-Oligocene boundary (within lowermost NP 21) is within the uppermost Yazoo Formation (Shubuta Clay Member) in places, and within the lowermost Bumpnose, Red Bluff, and Forest Hill Formations and Marianna Limestone elsewhere in the region.

  2. High altitude flight test of a disk gap band parachute deployed behind a bluff body at a Mach number of 2.69

    NASA Technical Reports Server (NTRS)

    Eckstrom, C.; Branscome, D. R.

    1972-01-01

    A flight test was conducted with a 55-foot diameter disk-gap-band parachute located at a trailing distance of 4.4 forebody diameters behind a 15-foot diameter bluff-body planetary entry aeroshell and attached instrumented payload. At the time of parachute deployment the aeroshell-payload combination was oscillating through an angle-of-attack range of plus or minus 40 deg. Continued oscillatory motion of the aeroshell-payload combination and similar motion of the parachute caused rapid changes in parachute shape and loading which resulted in extensive cloth damage in the band and outer disk-edge areas of the parachute canopy. During steady-state descent the damage parachute provided an effective-drag coefficient of about 0.33 which was about 60 percent of that expected.

  3. Preliminary results of hydrologic testing the composite middle sentinel bluffs basalt flow bottom at Borehole RRL-2 (3,247--3,344 feet)

    SciTech Connect

    Strait, S.R.; Spane, F.A. Jr.

    1982-11-01

    This report presents preliminary results and description of hydrologic test activities for the composite Middle Sentinel Bluffs basalt flow bottom (3,247-3,344 feet) at Borehole RRL-2. Hydrologic tests conducted include one constant discharge air-lift and two slug tests. Preliminary results indicate an observed hydraulic head for the test interval of 405.5 feet above mean sea level. Transmissivity values determined from hydrologic tests performed range between 203 and 847 ft{sup 2}/day, with an assigned best estimate of 770 ft{sup 2} day. The best estimate of equivalent hydraulic conductivity, based on an effective test thickness of 77.5 feet, is 9.9 ft/day.

  4. Forced sea-level change in a forearc basin related to subduction of a spreading ridge: the Fossil Bluff Group (Jurassic-Cretaceous), Alexander Island, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Macdonald, David

    2015-04-01

    During the Mesozoic, the Antarctic Peninsula was the site of an active volcanic arc related to the eastwards subduction of proto-Pacific oceanic crust. Alexander Island is the largest of the many islands that lie on the western (fore-arc) side of the Antarctic Peninsula; it forms one of the best-exposed ancient fore-arcs in the world. The pre-Tertiary rocks can be divided into two main units. The LeMay Group (Jurassic-Tertiary) forms the structural basement to Alexander Island and comprises greenschist-facies metasedimentary rocks. It is interpreted as a Mesozoic accretionary prism. The Fossil Bluff Group unconformably overlies and is faulted against the LeMay Group; it represents the sedimentary fill of a coeval fore-arc basin. Subduction ceased due to a series of Cenozoic ridge-trench collisions which began off Alexander Island at 50 Ma and got progressively younger to the north. However, the approach of the ridge can be inferred from the Mesozoic deposits of the Fossil Bluff Group (Jurassic-Cretaceous) in Alexander Island. In this paper, I will show that the ocean floor being subducted became progressively shallower through Jurassic and Cretaceous time (by at least 1,000 m). The result in the forearc basin was a sudden shallowing in water depths from at least 1,000 m at 125 Ma, to emergent at 100 Ma. This forced shallowing ended sedimentation in the basin and resulted in considerable topography on Alexander Island that persists to the present day.

  5. Hydrology, Water Quality, and Causes of Changes in Vegetation in the Vicinity of the Spring Bluff Nature Preserve, Lake County, Illinois, May 2007-August 2008

    USGS Publications Warehouse

    Kay, Robert T.; Miner, James J.; Maurer, Debbie A.; Knight, Charles W.

    2010-01-01

    Agriculture and urbanization have altered the hydrology and water quality of the coastal wetland complex along the shore of Lake Michigan at the Spring Bluff Nature Preserve and Illinois Beach State Park in northeastern Lake County, Ill., and the adjacent Chiwaukee Prairie State Natural Area in southeastern Wisconsin. Culverts, roads, ditches, and berms installed within the wetland complex have altered the natural directions of surface-water flow and likely have increased the natural hydroperiod in the Spring Bluff Nature Preserve and decreased it in the northern part of the Illinois Beach State Park. Relative to presettlement conditions, surface-water runoff into the wetlands likely is greater in quantity and higher in concentrations of several constituents, including chloride, nitrate, phosphorous, and suspended sediment. These constituent concentrations are affected by a variety of factors, including the amount of agricultural and urban land use in the watersheds. Hydrologic, chemical, and biologic processes within the wetland communities reduce the concentrations of these constituents in surface water before the water discharges to Lake Michigan by as much as 75 percent for chloride, 85 percent for nitrate, 66 percent for phosphorous, and more than an order of magnitude for suspended sediment. However, concentrations of phosphorous and suspended sediment in surface water increased within parts of the wetland complex. Given these changes, the floristic quality of these wetlands has been altered from the historic condition. Specifically, Typha spp. and Phragmites australis occur in greater numbers and over a larger area than in the past. The spread of Typha spp. and Phragmites australis appears to be enhanced by anthropogenic alterations within the wetland complex, such as increased water levels and duration of inundation and, possibly, increases in the total concentration of dissolved constituents in water.

  6. Age and correlation of the Pliocene Chowan River Formation of Virginia and northeastern North Carolina

    SciTech Connect

    Campbell, L.D. . Div. of Natural Sciences)

    1993-03-01

    Based on Aurora, North Carolina, radiometric ages and fossil assemblages, current literature equates the Chowan River and Bear Bluff formations. Age and correlation of the Pliocene Chowan River and Bear Bluff formations, assigning an age of approximately 2.5 ma. However, molluscan assemblages from the Chowan River stratotype and Virginian equivalents represent an older stage of molluscan assemblage evolution not contemperaneous with the 2.5 ma beds at Aurora. Rather, the Chowan River molluscan fauna is intermediate between that of the upper Yorktown (3.2 ma) and that of the older Waccamaw (2.5 ma). The Oxygen isotope model of Krantz (1991) postulates related transgressions at 2.7 and 2.9 ma, which coincide with the two members at the stratotype area and with the two-fold division of the unit in Virginia. In southern North Carolina, Chowan River-equivalent beds at Tar Heel and Elizabethtown have been assigned to the Bear Bluff Formation, a composite of non-contiguous beds ranging from 2.5 to 3.7 ma. No equivalents are known between Elizabethtown and southern Florida where beds 2 and 3 at the APAC pit in Sarasota appear correlative. Faunal assemblages of these beds remain imperfectly documented, but their intermediate character, younger than typical Pinecrest but older than typical Caloosahatchee, is evident from preliminary reports. The intermediate nature of the fauna containing index species once thought to be mutually exclusive, will necessitate a thorough revision of Pliocene index species zonation when the faunas become better known.

  7. Superfund Record of Decision (EPA Region 7): Mid-America Tanning site, Sergeant bBluff, IA. (First remedial action), September 1991

    SciTech Connect

    Not Available

    1991-09-24

    The 98.7-acre Mid-America Tanning site is a former leather tannery in Sergeant Bluff, Woodbury County, Iowa. Surrounding land use is mixed industrial and agricultural. A portion of the site is bordered by Oxbow Lake and lies within the 100-year floodplain. The Missouri River is approximately 1.5 miles to the southwest of the site and receives discharges from Oxbow Lake. The facility began onsite processing of animal hides in 1970. In 1980, the State confirmed the onsite burial of chromium-containing sludge in trenches, and the company was cited for permit violations. A 1985 EPA investigation identified excessive chromium contamination in onsite soil, sediment, and ground water. In 1990, EPA conducted a removal action that included excavating and consolidating onsite 1,290 cubic yards of sludge from the trench disposal area. The Record of Decision (ROD) addresses the contaminated soil, impoundment sediment and water, and the excavated trench material. A future ROD will address onsite ground water contamination. The primary contaminant of concern affecting the soil, sediment, debris, sludge, and surface water are metals including chromium and lead. The selected remedial action for the site is included.

  8. Preliminary Image Map of the 2007 Ammo Fire Perimeter, San Onofre Bluff Quadrangle, San Diego County, California

    USGS Publications Warehouse

    Clark, Perry S.; Scratch, Wendy S.; Bias, Gaylord W.; Stander, Gregory B.; Sexton, Jenne L.; Krawczak, Bridgette J.

    2008-01-01

    In the fall of 2007, wildfires burned out of control in southern California. The extent of these fires encompassed large geographic areas that included a variety of landscapes from urban to wilderness. The U.S. Geological Survey National Geospatial Technical Operations Center (NGTOC) is currently (2008) developing a quadrangle-based 1:24,000-scale image map product. One of the concepts behind the image map product is to provide an updated map in electronic format to assist with emergency response. This image map is one of 55 preliminary image map quadrangles covering the areas burned by the southern California wildfires. Each map is a layered, geo-registered Portable Document Format (.pdf) file. For more information about the layered geo-registered .pdf, see the readme file (http://pubs.usgs.gov/of/2008/1029/downloads/CA_Agua_Dulce_of2008-1029_README.txt). To view the areas affected and the quadrangles mapped in this preliminary project, see the map index (http://pubs.usgs.gov/of/2008/1029/downloads/CA_of2008_1029-1083_index.pdf) provided with this report.

  9. Habitat quality and recruitment success of cui-ui in the Truckee River downstream of Marble Bluff Dam, Pyramid Lake, Nevada

    USGS Publications Warehouse

    Scoppettone, G. Gary; Rissler, Peter H.; Salgado, J. Antonio; Harry, Beverly

    2013-01-01

    We compared cui-ui (Chasmistes cujus) recruitment from two reaches of the Truckee River with histories of severe erosional downcutting caused by a decline in Pyramid Lake surface elevation. In 1975, Marble Bluff Dam (MBD) was constructed 5 kilometers upstream of the extant mouth of the Truckee River to stabilize the upstream reach of the river; the downstream reach of the river remained unstable and consequently unsuitable for cui-ui recruitment. By the early 2000s, there was a decrease in the Truckee River’s slope from MBD to Pyramid Lake after a series of wet years in the 1990s. This was followed by changes in river morphology and erosion abatement. These changes led to the question as to cui-ui recruitment potential in the Truckee River downstream of MBD. In 2012, more than 7,000 cui-ui spawners were passed upstream of MBD, although an indeterminate number of cui-ui spawned downstream of MBD. In this study, we compared cui-ui recruitment upstream and downstream of MBD during a Truckee River low-flow year (2012). Cui-ui larvae emigration to Pyramid Lake began earlier and ended later downstream of MBD. A greater number of cui-ui larvae was produced downstream of MBD than upstream. This also was true for native Tahoe sucker (Catostomus tahoensis) and Lahontan redside (Richardsonius egregius). The improved Truckee River stability downstream of MBD and concomitant cui-ui recruitment success is attributed to a rise in Pyramid Lake's surface elevation. A decline in lake elevation may lead to a shift in stream morphology and substrate composition to the detriment of cui-ui reproductive success as well as the reproductive success of other native fishes.

  10. Quaternary geology of the Duck Hawk Bluffs, southwest Banks Island, Arctic Canada: a re-investigation of a critical terrestrial type locality for glacial and interglacial events bordering the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Evans, David J. A.; England, John H.; La Farge, Catherine; Coulthard, Roy D.; Lakeman, Thomas R.; Vaughan, Jessica M.

    2014-05-01

    Duck Hawk Bluffs, southwest Banks Island, is a primary section (8 km long and 60 m high) in the western Canadian Arctic Archipelago exposing a long record of Quaternary sedimentation adjacent to the Arctic Ocean. A reinvestigation of Duck Hawk Bluffs demonstrates that it is a previously unrecognized thrust-block moraine emplaced from the northeast by Laurentide ice. Previous stratigraphic models of Duck Hawk Bluffs reported a basal unit of preglacial fluvial sand and gravel (Beaufort Fm, forested Arctic), overlain by a succession of three glaciations and at least two interglacials. Our observations dismiss the occurrence of preglacial sediments and amalgamate the entire record into three glacial intervals and one prominent interglacial. The first glacigenic sedimentation is recorded by an ice-contact sandur containing redeposited allochthonous organics previously assigned to the Beaufort Fm. This is overlain by fine-grained sediments with ice wedge pseudomorphs and well-preserved bryophyte assemblages corresponding to an interglacial environment similar to modern. The second glacial interval is recorded by ice-proximal mass flows and marine rhythmites that were glacitectonized when Laurentide ice overrode the site from Amundsen Gulf to the south. Sediments of this interval have been reported to be magnetically reversed (>780 ka). The third interval of glacigenic sedimentation includes glacifluvial sand and gravel recording the arrival of Laurentide ice that overrode the site from the northeast (island interior) depositing a glacitectonite and constructing the thrust block moraine that comprises Duck Hawk Bluffs. Sediments of this interval have been reported to be magnetically normal (<780 ka). The glacitectonite contains a highly deformed melange of pre-existing sediments that were previously assigned to several formally named, marine and interglacial deposits resting in an undeformed sequence. In contrast, the tectonism associated with the thrust block moraine imparted pervasive deformation throughout all underlying units, highlighted by a previously unrecognized raft of Cretaceous bedrock. During this advance, Laurentide ice from the interior of Banks Island coalesced with an ice stream in Amundsen Gulf, depositing the interlobate Sachs Moraine that contains shells as young as 24 cal ka BP (Late Wisconsinan). During deglaciation, meltwater emanating from these separating ice lobes deposited outwash that extended to deglacial marine limit (11 m asl) along the west coast of Banks Island. Our new stratigraphic synthesis fundamentally revises and simplifies the record of past Quaternary environments preserved on southwest Banks Island, which serves as a key terrestrial archive for palaeoenvironmental change.

  11. Sequential palynostratigraphy of the Queen City and Weches formations (Middle Eocene Claiborne Group), southeast central Texas

    SciTech Connect

    Elsik, W.C. )

    1993-02-01

    Palynomorph sequences of several orders of magnitude were found in the Queen City and Weches formations respectively at Six Mile and Burleson bluffs on the Brazos River, Milam and Burleson counties, Texas. The long term development of the subtropical to tropical Claibornian palynoflora included Engelhardtia spp., Friedrichipollis claibornensis, Nudopollis terminalis, Pollenites laesius and Symplocoipollenites spp. Shorter term fluctuations in sea level were reflected by common herbaceous pollen in the Queen City, and common mangrove pollen in the Weches. Paleoenvironments were marginally to fully marine; dinocysts occurred throughout. The Wetzeliella group of dinocysts were present only in the Queen City at Six Mile Bluff. Late Paleocene to Early Eocene pollen, and Early Middle Eocene pollen with last effective occurrences near the Queen City and Weches boundary included Aesculiidites circumstriatus, Annona foveoreticulata and a new species of Platycarya. Five short term warmer-cooler couplet events were represented by successive abundance peaks of Juglandaceae followed by Ulmus; Alnus supports the three upper Ulmus peaks. One deep water event was recorded by an abundance of fresh water Pediastrum at the Queen City and Weches boundary. That boundary event was bracketed by two of the Alnus and Ulmus peaks.

  12. Bluff and Bull in Education

    ERIC Educational Resources Information Center

    Sassoon, David

    2005-01-01

    Telling a lie, according to Harry G. Frankfurt, is different from engaging in bullshit because, while a lie is designed to insert a particular falsehood at a specific point in a set or system of beliefs in order to avoid the consequences of having that occupied by truth, bullshit neither misrepresents the state of affairs to which it refers nor

  13. High-resolution, paired geochemical-paleomagnetic stratigraphy of the Sentinel Bluffs Member of the Grande Ronde Basalt, Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Sawlan, M. G.; Hagstrum, J. T.

    2012-12-01

    The Sentinel Bluffs Member (SB) of the Grande Ronde Basalt (GRB) is the youngest stratigraphic unit of the GRB, and is distinguished from other lava flows within the GRB's upper normal polarity magnetozone (N2) by its relatively high MgO content. We collected co-located samples in SB lava flows for major and trace element (XRF) geochemical and paleomagnetic analyses from 7 stratigraphic sections in the central and eastern Columbia River Gorge, on the southwestern Columbia Plateau, at Sentinel Gap on the western Plateau, and at Patrick Grade in the northern Blue Mountains of eastern WA. For the Sentinel Gap section we have adopted the paleomagnetic data from Coe et al. [1978, Rockwell Hanford report RHO-BWI-ST-2], except for our sampling of the Levering flow (not previously sampled) and resampling of their SB flow "H". Paleomagnetic directions for SB flows define 7 stratigraphically controlled groups (I-VII) varying primarily in inclination. Groups I, III, and V have moderate inclinations (means of 55°-57°), groups II and IV have steeper inclinations (67°-69°), and groups VI and VII have the steepest inclinations (72°-78°). SB lava flows exhibit relatively large chemical variations, spanning nearly 1 wt% MgO. Within this span, we recognize 11 discrete chemical groups (1-11, numbered in stratigraphic order) mainly on the basis of TiO2-MgO variations. Early SB eruptions include low- and high-Cr subgroups, and chemical groups 1 and 2 (paleomagnetic groups I-III) are subdivided on the basis of a ~2x difference in Cr abundances (e.g., 16-20 ppm Cr in groups 1a and 2a, 32-38 ppm Cr in groups 1b and 2b). Low-Cr flows are observed only in the lower parts of the SB stratigraphy. Three group 1 (I-II) lava flows that are the lowest SB flows in three sections have similar major element abundances, but differ from each other either in trace element abundances and/or paleomagnetic direction. We infer that the earliest SB flows have moderate inclinations (56°) and include both low-Cr and hi-Cr flows. Systematic decreases in TiO2 and increases in MgO are observed within groups 1-5 (I-III) and 9-11 (VI-VII) with decreasing age. Having similar MgO values, the younger flows of groups 9-11 have distinctly lower TiO2 relative to groups 1-5. Chemical groups 6-8 (IV-V) have relatively high MgO (~4.9-5.2 wt%), intermediate TiO2, and somewhat higher Cr (40-46 ppm) relative to lava flows within groups 1-5 and 9-11 having similar MgO values. With one exception, observed breaks between geochemical and paleomagnetic groups are not contemporaneous as shifts in paleomagnetic direction apparently occurred during eruption of flows within a single chemical group. A total of 22 SB flows are defined by geochemistry and physical flow boundaries. Accounting for differences in paleomagnetic directions within the chemical groups, as many as 29 flows are represented. We attribute the high resolution of our geochemical data to rigorous sampling and lab preparation protocols that minimized alteration products in the material analyzed. Our combined geochemical and paleomagnetic data enables correlation of individual flows or small flow packages (i.e. 2-4 flows) from locations separated by as much as 200 km. These results implicate a high degree of chemical homogeneity within individual SB flows.

  14. Alteration, mass conservation, and magmatic compositions of lavas of the Columbia River flood basalt province: Insights from the Sentinel Bluffs Member, Grande Ronde Basalt

    NASA Astrophysics Data System (ADS)

    Sawlan, M. G.

    2013-12-01

    Understanding magmatic processes involved in flood basalt volcanism, and the ability to correlate flows within the voluminous, widespread lava fields requires accurate characterization of their magmatic geochemistry. Although evidence of alteration is widespread, modifications to lava chemistry by secondary processes are poorly understood. This results in uncertainty in the interpretation of geochemical analyses of Columbia River Basalt Group lava flows, particularly those of the Grande Ronde Basalt (GRB), in which chemical differences between the lavas are subtle. This problem is addressed here using major and trace element analyses (XRF) of samples of the Sentinel Bluffs Member (SB) of the GRB collected from multiple stratigraphic sections within the Columbia Plateau, Columbia River Gorge and Coast Ranges. Sixteen chemical groups, comprising 1-3 flows each, are recognized among multiple SB lava compositions. Flows assigned to three or four successive chemical groups are, in turn, assigned to more broadly defined chemical series based on shared characteristics such as immobile element ratios. Magmatic and alteration trends among SB compositions are clearly distinguished in Al-Ti variations. Magmatic trends are defined by inverse correlation of Al2O3 and TiO2. Alteration trends, extending from the magmatic array to higher abundances, are characterized by constant Al2O3/TiO2. Paired enrichments in Al and Ti, as well as other immobile elements, result from concentration in the residuum of altered rock that has lost mass due to soluble cation removal. Such enrichments are inversely proportional to mass loss. A mass conservation index (MCI), derived from Al-Ti systematics, quantifies mass retention and has multiple applications. MCI normalization eliminates residual concentration accompanying mass loss such that MCI-normalized immobile element abundances in altered rock agree with those in high-MCI rock. Compositions filtered to high-MCI values more closely reflect magmatic abundances of highly mobile elements, such as K and Ba, but some mobility not accounted by MCI normalization is evident. MCI-normalized abundances indicate which mobile elements have been enriched or depleted during alteration, and can characterize the composition of material removed. The slope of correlated MCI-normalized abundances and MCI corresponds to the weight fraction of total mass loss. That such correlations are observed indicates a consistent composition of material removed, which, in turn, suggests that alteration selectively affects particular phases. In SB lavas, depletions of Fe, Si, and Mg account for most mass loss; depletions in Ca are minor. The observed depletions indicate removal primarily of pyroxene and Fe-oxide. The MCI-based methodology provides a framework for quantifying effects of alteration on lava chemistry and clarifying magma compositions that provide a foundation for petrogenetic analysis. It is likely applicable to other lavas in this flood basalt province, as well as other volcanic rocks influenced by secondary processes.

  15. Formation of lunar basin rings

    USGS Publications Warehouse

    Hodges, C.A.; Wilhelms, D.E.

    1978-01-01

    The origin of the multiple concentric rings that characterize lunar impact basins, and the probable depth and diameter of the transient crater have been widely debated. As an alternative to prevailing "megaterrace" hypotheses, we propose that the outer scarps or mountain rings that delineate the topographic rims of basins-the Cordilleran at Orientale, the Apennine at Imbrium, and the Altai at Nectaris-define the transient cavities, enlarged relatively little by slumping, and thus are analogous to the rim crests of craters like Copernicus; inner rings are uplifted rims of craters nested within the transient cavity. The magnitude of slumping that occurs on all scarps is insufficient to produce major inner rings from the outer. These conclusions are based largely on the observed gradational sequence in lunar central uplifts:. from simple peaks through somewhat annular clusters of peaks, peak and ring combinations and double ring basins, culminating in multiring structures that may also include peaks. In contrast, belts of slump terraces are not gradational with inner rings. Terrestrial analogs suggest two possible mechanisms for producing rings. In some cases, peaks may expand into rings as material is ejected from their cores, as apparently occurred at Gosses Bluff, Australia. A second process, differential excavation of lithologically diverse layers, has produced nested experimental craters and is, we suspect, instrumental in the formation of terrestrial ringed impact craters. Peak expansion could produce double-ring structures in homogeneous materials, but differential excavation is probably required to produce multiring and peak-in-ring configurations in large lunar impact structures. Our interpretation of the representative lunar multiring basin Orientale is consistent with formation of three rings in three layers detected seismically in part of the Moon-the Cordillera (basin-bounding) ring in the upper crust, the composite Montes Rook ring in the underlying, more coherent "heald" crust, and an innermost, 320-km ring at the crust-mantle interface. Depth-diameter ratios of 1 10to 1 15 are consistent with this interpretation and suggest that volumes of transient cavities and hence of basin ejecta may be considerably greater than commonly assumed. ?? 1978.

  16. CO2 Sequestration Potential of Texas Low-Rank Coals

    SciTech Connect

    Duane McVay; Walter Ayers, Jr.; Jerry Jensen; Jorge Garduno; Gonzola Hernandez; Rasheed Bello; Rahila Ramazanova

    2006-08-31

    Injection of CO{sub 2} in coalbeds is a plausible method of reducing atmospheric emissions of CO{sub 2}, and it can have the additional benefit of enhancing methane recovery from coal. Most previous studies have evaluated the merits of CO{sub 2} disposal in high-rank coals. The objective of this research was to determine the technical and economic feasibility of CO{sub 2} sequestration in, and enhanced coalbed methane (ECBM) recovery from, low-rank coals in the Texas Gulf Coast area. Our research included an extensive coal characterization program, including acquisition and analysis of coal core samples and well transient test data. We conducted deterministic and probabilistic reservoir simulation and economic studies to evaluate the effects of injectant fluid composition (pure CO{sub 2} and flue gas), well spacing, injection rate, and dewatering on CO{sub 2} sequestration and ECBM recovery in low-rank coals of the Calvert Bluff formation of the Texas Wilcox Group. Shallow and deep Calvert Bluff coals occur in two, distinct, coalbed gas petroleum systems that are separated by a transition zone. Calvert Bluff coals < 3,500 ft deep are part of a biogenic coalbed gas system. They have low gas content and are part of a freshwater aquifer. In contrast, Wilcox coals deeper than 3,500 ft are part of a thermogenic coalbed gas system. They have high gas content and are part of a saline aquifer. CO{sub 2} sequestration and ECBM projects in Calvert Bluff low-rank coals of East-Central Texas must be located in the deeper, unmineable coals, because shallow Wilcox coals are part of a protected freshwater aquifer. Probabilistic simulation of 100% CO{sub 2} injection into 20 feet of Calvert Bluff coal in an 80-acre 5-spot pattern indicates that these coals can store 1.27 to 2.25 Bcf of CO{sub 2} at depths of 6,200 ft, with an ECBM recovery of 0.48 to 0.85 Bcf. Simulation results of flue gas injection (87% N{sub 2}-13% CO{sub 2}) indicate that these same coals can store 0.34 to 0.59 Bcf of CO{sub 2} with an ECBM recovery of 0.68 to 1.20 Bcf. Economic modeling of CO{sub 2} sequestration and ECBM recovery indicates predominantly negative economic indicators for the reservoir depths (4,000 to 6,200 ft) and well spacings investigated, using natural gas prices ranging from $2 to $12 per Mscf and CO{sub 2} credits based on carbon market prices ranging from $0.05 to $1.58 per Mscf CO{sub 2} ($1.00 to $30.00 per ton CO{sub 2}). Injection of flue gas (87% N{sub 2} - 13% CO{sub 2}) results in better economic performance than injection of 100% CO{sub 2}. CO{sub 2} sequestration potential and methane resources in low-rank coals of the Lower Calvert Bluff formation in East-Central Texas are significant. The potential CO{sub 2} sequestration capacity of the coals ranges between 27.2 and 49.2 Tcf (1.57 and 2.69 billion tons), with a mean value of 38 Tcf (2.2 billion tons), assuming a 72.4% injection efficiency. Estimates of recoverable methane resources range between 6.3 and 13.6 Tcf, with a mean of 9.8 Tcf, assuming a 71.3% recovery factor. Moderate increases in gas prices and/or carbon credits could generate attractive economic conditions that, combined with the close proximity of many CO{sub 2} point sources near unmineable coalbeds, could enable commercial CO{sub 2} sequestration and ECBM projects in Texas low-rank coals. Additional studies are needed to characterize Wilcox regional methane coalbed gas systems and their boundaries, and to assess potential of other low-rank coal beds. Results from this study may be transferable to other low-rank coal formations and regions.

  17. Concept Formation.

    ERIC Educational Resources Information Center

    Vaidya, Narendera

    This document, published in India by the Regional College of Education, deals with 13 subjects: the tough context (thinking), definitions of concept, functions of concept, the process of concept formation, discriminant learning, mediation process, second signalling system, factors affecting concept formation, studies in concept formation, the

  18. Lithofacies of Spencer Formation, western Tualatin Valley, Oregon

    SciTech Connect

    Van Atta, R.O.

    1986-04-01

    The Spencer Formation crops out in a narrow band that trends north-northwest on the western edge of the Willamette and Tualatin Valleys, Oregon. It apparently conformably overlies mud rocks of either the Yamhill or the Nestucca Formation and is conformably overlain by the Pittsburgh Bluff Formation. The Spencer Formation consists of two members (informal): a lower highly micaceous sandstone (800-1000 ft) and an upper member that is micaceous siltstone and mudstone (1000-1300 ft). The lower member includes an upper part that is light-gray to creamy-gray, silty to muddy, pebbly lithic arkose to feldspathic litharenite, with minor arkose. Sorting is poor and beds may be laminated to ripple cross-laminated or massive and bioturbated with abundant mollusk shells, carbonized wood, and burrows. The lower part of the lower member is medium-gray to greenish-gray, silty, pumiceous lithic arkose to feldspathic litharenite. The texture tends to be more uniform and better sorted than that of the upper part of the member. Bedding is commonly massive due to bioturbation. The upper member is medium to dark-gray mudstone with thin pebble-conglomerate lenses. It intertongues with the lower member. Bioturbation, burrows, and carbonized wood are common. The trend in depositional environments appears to be from outer to mid-neritic (lower part, lower member) to shallow neritic, nearshore, and lagoonal (upper part, lower member, and upper member). The provenance of the Spencer Formation includes both proximal volcanics and distant plutonic and high-grade metamorphics.

  19. Godiva Rim Member: A new stratigraphic unit of the Green River Formation in southwest Wyoming and northwest Colorado. Geology of the Eocene Wasatch, Green River, and Bridger (Washakie) Formations, Greater Green River Basin, Wyoming, Utah, and Colorado. Professional paper

    SciTech Connect

    Roehler, H.W.

    1991-01-01

    The report names and describes the Godiva Rim Member of the Green River Formation in the eastern part of the Washakie basin in southwest Wyoming and the central part of the Sand Wash basin in northwest Colorado. The Godiva Rim Member comprises lithofacies of mixed mudflat and lacustrine origin situated between the overlying lacustrine Laney Member of the Green River Formation and the underlying fluvial Cathedral Bluffs Tongue of the Wasatch Formation. The Godiva Rim Member is laterally equivalent to and grades westward into the LaClede Bed of the Laney Member. The Godiva Rim Member of the Green River Formation was deposited along the southeast margins of Lake Gosiute and is correlated to similar lithologic units that were deposited along the northeast margins of Lake Uinta in the Parachute Creek Member of the Green River Formation. The stratigraphic data presented provide significant evidence that the two lakes were periodically connected around the east end of the Uinta Mountains during the middle Eocene.

  20. Galaxy formation

    PubMed Central

    Peebles, P. J. E.

    1998-01-01

    It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z ? 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation. PMID:9419326

  1. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that most single stars should have rocky planets in orbit about them; the frequency of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Models for the formation of the giant planets found in recent radial velocity searches are discussed.

  2. Planet formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1993-01-01

    Models of planetary formation are developed using the present single example of a planetary system, supplemented by limited astrophysical observations of star-forming regions and circumstellar disks. The solar nebula theory and the planetesimal hypothesis are discussed. The latter is found to provide a viable theory of the growth of the terrestrial planets, the cores of the giant planets, and the smaller bodies present in the solar system. The formation of solid bodies of planetary size should be a common event, at least around young stars which do not have binary companions orbiting at planetary distances. Stochastic impacts of large bodies provide sufficient angular momentum to produce the obliquities of the planets. The masses and bulk compositions of the planets can be understood in a gross sense as resulting from planetary growth within a disk whose temperature and surface density decreased with distance from the growing sun.

  3. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates.

  4. 40. December 20, 1933 View of portal site, tunnel no. ...

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

    40. December 20, 1933 View of portal site, tunnel no. 1, CWA men facing the portal. "Stripping the hillside grule sic formation between tunnels 1 and 2." - Scotts Bluff Summit Road, Gering, Scotts Bluff County, NE

  5. CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

    SciTech Connect

    Duane A. McVay; Walter B. Ayers Jr; Jerry L. Jensen

    2004-11-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. there were two main objectives for this reporting period. first, they wanted to collect wilcox coal samples from depths similar to those of probable sequestration sites, with the objective of determining accurate parameters for reservoir model description and for reservoir simulation. The second objective was to pursue opportunities for determining permeability of deep Wilcox coal to use as additional, necessary data for modeling reservoir performance during CO{sub 2} sequestration and enhanced coalbed methane recovery. In mid-summer, Anadarko Petroleum Corporation agreed to allow the authors to collect Wilcox Group coal samples from a well that was to be drilled to the Austin Chalk, which is several thousand feet below the Wilcox. In addition, they agreed to allow them to perform permeability tests in coal beds in an existing shut-in well. Both wells are in the region of the Sam K. Seymour power station, a site that they earlier identified as a major point source of CO{sub 2}. They negotiated contracts for sidewall core collection and core analyses, and they began discussions with a service company to perform permeability testing. To collect sidewall core samples of the Wilcox coals, they made structure and isopach maps and cross sections to select coal beds and to determine their depths for coring. On September 29, 10 sidewall core samples were obtained from 3 coal beds of the Lower Calvert Bluff Formation of the Wilcox Group. The samples were desorbed in 4 sidewall core canisters. Desorbed gas samples were sent to a laboratory for gas compositional analyses, and the coal samples were sent to another laboratory to measure CO{sub 2}, CH{sub 4}, and N{sub 2} sorption isotherms. All analyses should be finished by the end of December. A preliminary report shows methane content values for the desorbed coal samples ranged between 330 and 388 scf/t., on ''as received'' basis. Residual gas content of the coals was not included in the analyses, which results in an approximate 5-10% underestimation of in-situ gas content. Coal maps indicate that total coal thickness is 40-70 ft in the Lower Calvert Bluff Formation of the Wilcox Group in the vicinity of the Sam K. Seymour power plant. A conservative estimate indicates that methane in place for a well on 160-acre spacing is approximately 3.5 Bcf in Lower Calvert Bluff coal beds. When they receive sorption isotherm data from the laboratory, they will determine the amount of CO{sub 2} that it may be possible to sequester in Wilcox coals. In December, when the final laboratory and field test data are available, they will complete the reservoir model and begin to simulate CO{sub 2} sequestration and enhanced CH{sub 4} production.

  6. Amphiplex Formation

    NASA Astrophysics Data System (ADS)

    Petersen, Shannon; Laaser, Jennifer; Lodge, Timothy

    2015-03-01

    Polymer-micelle complexes are currently under heavy investigation due to their potential applications in targeted drug delivery and gene therapy, yet the dynamics of the complex formation is still relatively unstudied. By varying the ratios of poly(styrene sulfonate) chains and cationic poly(dimethylaminoethyl methacrylate)-b-poly(styrene) micelles and the ionic strength of the system, we created a variety of complex configurations of different sizes and charges. The complexes were characterized dynamic light scattering and zeta potential measurements which provided information regarding the hydrodynamic radius, distribution of sizes, and effective charge.

  7. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  8. 76 FR 4391 - Calvert Cliffs Nuclear Power Plant, LLC, Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-25

    ... significant impact on the quality of the human environment (76 FR 1469); published on January 10, 2011. This... items, that the rate of energy release, hydrogen generation, and cladding oxidation from the metal/water... adequate acceptance criteria for the ECCS, and to ensure that cladding oxidation and hydrogen...

  9. 77 FR 47121 - Calvert Cliffs Nuclear Power Plant, LLC; Calvert Cliffs Nuclear Power Plant, Units 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-07

    ..., ``Fatigue Management for Nuclear Power Plant Personnel,'' endorses the Nuclear Energy Institute (NEI) report... in a violation of the Atomic Energy Act of 1954, as amended, or the Commission's regulations... construction impact; and there is no significant increase in the potential for or consequences from...

  10. P Formation

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Balaraju, J. N.; Huang, Yizhong; Tay, Yee Yan; Shen, Yiqiang; Tsakadze, Zviad; Chen, Zhong

    2014-11-01

    The voids formed in the Ni3P layer during reaction between Sn-based solders and electroless Ni-P metallization is an important cause of rapid degradation of solder joint reliability. In this study, to suppress formation of the Ni3P phase, an electrolessly plated Ni-Sn-P alloy (6-7 wt.% P and 19-21 wt.% Sn) was developed to replace Ni-P. The interfacial microstructure of electroless Ni-Sn-P/Sn-3.5Ag solder joints was investigated after reflow and solid-state aging. For comparison, the interfacial reaction in electroless Ni-P/Sn-3.5Ag solder joints under the same reflow and aging conditions was studied. It was found that the Ni-Sn-P metallization is consumed much more slowly than the Ni-P metallization during soldering. After prolonged reaction, no Ni3P or voids are observed under SEM at the Ni-Sn-P/Sn-3.5Ag interface. Two main intermetallic compounds, Ni3Sn4 and Ni13Sn8P3, are formed during the soldering reaction. The reason for Ni3P phase suppression and the overall mechanisms of reaction at the Ni-Sn-P/Sn-3.5Ag interface are discussed.

  11. Pattern Formation

    NASA Astrophysics Data System (ADS)

    Hoyle, Rebecca

    2006-03-01

    From the stripes of a zebra and the spots on a leopard's back to the ripples on a sandy beach or desert dune, regular patterns arise everywhere in nature. The appearance and evolution of these phenomena has been a focus of recent research activity across several disciplines. This book provides an introduction to the range of mathematical theory and methods used to analyse and explain these often intricate and beautiful patterns. Bringing together several different approaches, from group theoretic methods to envelope equations and theory of patterns in large-aspect ratio-systems, the book also provides insight behind the selection of one pattern over another. Suitable as an upper-undergraduate textbook for mathematics students or as a fascinating, engaging, and fully illustrated resource for readers in physics and biology, Rebecca Hoyle's book, using a non-partisan approach, unifies a range of techniques used by active researchers in this growing field. Accessible description of the mathematical theory behind fascinating pattern formation in areas such as biology, physics and materials science Collects recent research for the first time in an upper level textbook Features a number of exercises - with solutions online - and worked examples

  12. CO2 Sequestration Potential of Texas Low-Rank Coals

    SciTech Connect

    Duane A. McVay; Walter B. Ayers Jr; Jerry L. Jensen

    2006-07-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (ECBM) recovery as an added benefit of sequestration. The main objectives for this reporting period were to (1) estimate the potential for CO{sub 2} sequestration in, and methane production from, low-rank coals of the Lower Calvert Bluff Formation of the Wilcox Group in the east-central Texas region, (2) quantify uncertainty associated with these estimates, (3) conduct reservoir and economic analyses of CO{sub 2} sequestration and ECBM production using horizontal wells, and (4) compare the results with those obtained from previous studies of vertical wells. To estimate the total volumes of CO{sub 2} that may be sequestered in, and total volumes of methane that can be produced from, the Wilcox Group low-rank coals in east-central Texas, we used data provided by Anadarko Petroleum Corporation, data obtained during this research, and results of probabilistic simulation modeling studies we conducted. For the analysis, we applied our base-case coal seam characteristics to a 2,930-mi{sup 2} (1,875,200-ac) area where Calvert Bluff coal seams range between 4,000 and 6,200 ft deep. Results of the probabilistic analysis indicate that potential CO{sub 2} sequestration capacity of the coals ranges between 27.2 and 49.2 Tcf (1.57 and 2.69 billion tons), with a mean value of 38 Tcf (2.2 billion tons), assuming a 72.4% injection efficiency. Estimates of recoverable methane resources, assuming a 71.3% recovery factor, range between 6.3 and 13.6 Tcf, with a mean of 9.8 Tcf. As part of the technology transfer for this project, we presented the paper SPE 100584 at the 2006 SPE Gas Technology Symposium held in Calgary, Alberta, Canada, on May 15-18, 2006. Also, we submitted an abstract to be considered for inclusion in a special volume dedicated to CO{sub 2} sequestration in geologic media, which is planned for publication by the American Association of Petroleum Geologists.

  13. Ice Complex formation in arctic East Siberia during the MIS3 Interstadial

    NASA Astrophysics Data System (ADS)

    Wetterich, Sebastian; Tumskoy, Vladimir; Rudaya, Natalia; Andreev, Andrei A.; Opel, Thomas; Meyer, Hanno; Schirrmeister, Lutz; Hls, Matthias

    2014-01-01

    A continuous 15 m long sequence of Ice Complex permafrost (Yedoma) exposed in a thermo-cirque at the southern coast of Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Dmitry Laptev Strait) was studied to reconstruct past landscape and environmental dynamics. The sequence accumulated during the Marine Isotope Stage 3 (MIS3) Interstadial between >49 and 29 ka BP in an ice-wedge polygon. The frozen deposits were cryolithologically described and sampled on a vertical bluff between two ice wedges. According to sedimentological and geochronological data, the section is subdivided into three units which correlate with environmental conditions of the early, middle, and late MIS3 period. Palynological data support this stratification. The stable isotope signature of texture ice in the polygon structure reflects fractionation due to local freeze-thaw processes, while the signature of an approximately 5 m wide and more than 17 m high ice wedge fits very well into the regional stable-water isotope record. Regional climate dynamics during the MIS3 Interstadial and local landscape conditions of the polygonal patterned ground controlled the Ice Complex formation. The sequence presented here completes previously published MIS3 permafrost records in Northeast Siberia. Late Quaternary stadial-interstadial climate variability in arctic West Beringia is preserved at millennial resolution in the Ice Complex. A MIS3 climate optimum was revealed between 48 and 38 ka BP from the Ice Complex on Bol'shoy Lyakhovsky Island.

  14. Cave Formations and Waterlines

    USGS Multimedia Gallery

    A series of speleothems, or cave formations, in the Caverns of Sonora. A prior waterline can be seen in the formations where the color changes from primarily white (formations formed in the air) to more beige (formations formed underwater). In addition, the previously submerged formations are larger...

  15. Humidity effects on photochemical aerosol formation in the SO 2-NO-C 3H 6-air system

    NASA Astrophysics Data System (ADS)

    Izumi, Katsuyuki; Mizuochi, Motoyuki; Murano, Kentaro; Fukuyama, Tsutomu

    In order to investigate the effects of humidity on the gas-phase oxidation of SO 2 in polluted air and on the subsequent aerosol formation process, photoirradiation experiments were carried out by means of a 4-m 3 chamber, in which mixtures containing SO 2, NO and C 3H 6 with concentrations in the ppm range were exposed to simulated solar radiation in different relative humidity (r.h.) conditions. The total amount of oxidized SO 2 was quantified from the SO 42- yield determined by the chemical analysis of the aerosol product, and a part due to the oxidation by the OH radical was evaluated by estimating the OH concentration from the decay rate of C 3H 6. The remaining part was assigned to the oxidation by the Criegee intermediate, as it had a good correlation with the progress of the O 3 + C 3H 6 reaction. The contributions of the two oxidizing species to the total conversion and the oxidation rate of SO 2 were measured as functions of r.h. As a result, experimental evidence was obtained for the prediction of Calvert and Stockwell's (1983, Envir. Sci. Technol. 17, 428A-443A) simulation that the oxidation due to the Criegee intermediate was retarded by the increase in humidity. The OH contribution, on the other hand, was almost independent of r.h. It was observed consequently that the total oxidized amount of SO 2 considerably decreased as r.h. was higher. The humidity effect on the aerosol formation process was found to be more complicated than the effect on the gas-phase chemistry. The maximum rate of increase in the particle number concentration rose linearly with increasing r.h., but the number concentration itself measured at its maximum or at the end of the irradiation reached a ceiling value around r.h. = 30% and went down for higher r.h. The average panicle size in the final stage of the reaction showed a minimum around the same r.h. at which the number concentration was maximum. The H 2SO 4 concentration in the mist particles, however, decreased monotonically as r.h. got higher. It was suggested that these different responses against the increase in humidity resulted from the cooperation of several processes such as the H 2SO 4 monomer formation, the H 2O condensation, the particle coagulation, etc., which had different dependences on r.h.

  16. Low-frequency unsteadiness in the vortex formation region of a circular cylinder

    NASA Astrophysics Data System (ADS)

    Lehmkuhl, O.; Rodrguez, I.; Borrell, R.; Oliva, A.

    2013-08-01

    The presence of low-frequency fluctuations in the wake of bluff bodies have been observed in several investigations. Even though the flow past a circular cylinder at Re = 3900 (Re = UrefD/?) has been the object of several experimental and numerical investigations, there is a large scattering in the average statistics in the near wake. In the present work, the flow dynamics of the near wake region behind a circular cylinder has been investigated by means of direct numerical simulations and statistics have been computed for more than 858 shedding cycles. The analysis of instantaneous velocity signals of several probes located in the vortex formation region, point out the existence of a low-frequency fluctuation at the non-dimensional frequency of fm = 0.0064. This large-scale almost periodic motion seems to be related with the modulation of the recirculation bubble which causes its shrinking and enlargement over the time. Two different configurations have been identified: (i) a high-energy mode with larger fluctuations in the shear-layer and in the vortex formation region (Mode H) and (ii) a low-energy mode with weaker fluctuations in the shear layer (Mode L). The influence of such a low-frequency in the wake topology has been studied not only by means of the phase-average flow field for each mode, but also by the analysis of the time-average first- and second-order statistics of each wake mode. The results are compared with the long-term averaged solution and with results in the existing literature.

  17. Formate Formation and Formate Conversion in Biological Fuels Production

    PubMed Central

    Crable, Bryan R.; Plugge, Caroline M.; McInerney, Michael J.; Stams, Alfons J. M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production. PMID:21687599

  18. What is conventional format?

    Atmospheric Science Data Center

    2014-12-08

    ... HDF-EOS format attempts to reproduce the data content of the original products, only changing the data format. However, there are some ... the same Space Oblique Mercator (SOM) projection as the original products. Conventional Grid Product ...

  19. Star Formation in Galaxies

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  20. The formation of galaxies

    NASA Technical Reports Server (NTRS)

    Efstathiou, G.; Silk, J.

    1983-01-01

    Current models of galaxy formation are examined in a review of recent observational and theoretical studies. Observational data on elliptical galaxies, disk galaxies, luminosity functions, clustering, and angular fluctuations in the cosmic microwave background are summarized. Theoretical aspects discussed include the origin and early evolution of small fluctuations, matter and radiation fluctuations, the formation of large-scale structure, dissipationless galaxy formation, galaxy mergers, dissipational galaxy formation, and the implications of particle physics (GUTs, massive neutrinos, and gravitinos) for cosmology.

  1. FORMCON -- Data Format Conversion

    NASA Astrophysics Data System (ADS)

    Lawden, M. D.; Pearce, Dave

    Two data format conversion utilities are available: - IPCSIN: Convert IPCS data to Starlink format. - VICARIN: Convert VICAR data to Starlink format. The Starlink format referred to is that used by the INTERIM Starlink environment described in SUN/4 and used by programs such as those in the ASPIC package. The input data is assumed to be held on magnetic tape. Both these programs are Starlink Application Programs and should be used within the INTERIM environment.

  2. Role of extensional tectonics in the formation of Talladega belt--Blue Ridge successor basins

    SciTech Connect

    Tull, J.F. . Dept. of Geology)

    1993-03-01

    Polydeformed and metamorphosed sequences occurring unconformably above the Cambrian-Ordovician (C-O) miogeoclinal sequence are nested within the Talladega belt (Talladega Group-TG) and Blue Ridge (Mineral Bluff Group-MBG). These successor basin sequences are 2.5--3 km thick and have a possible age range from Ordovician to Devonian, representing the youngest stratigraphic units east of the foreland. They are dominated by turbiditic metaclastic rocks derived from erosion of Grenville basement and its overlying cover of clastic and carbonate rock. Bimodal volcanic rocks occur in the TG, and within-plate mafic extrusive rocks are found in the MBG. The TG consists of a coarsening, thickening, and shallowing upward sequence with a submarine fan-like unit (Lay Dam Formation-LDF) at the base. The LDF contains a thick proximal boulder-bearing olistostromal facies with debris fan lobes stacked vertically and shed from a proximal fault scarp to the SE or S. The vertical stacking of olistostromal deposits, absence of crystalline-cored thrust sheets of this age at the structural top of the basin, and other relationships indicate that the basin did not result from detached deformation to the SE or transcurrent faulting, but rather from extensional faulting. Relationships within the C-O carbonate sequence (Sylacauga Marble Group) unconformably below the TG indicate that the TG basin developed above shallow shelf miogeoclinal rocks inboard of the continental margin hinge line, and thus indicate that Silurian-Devonian extensional structures affected relatively thick Laurentian crust. Similarities in lithofacies and stratigraphic sequence between the TG and MBG indicate that the settling of the MBG may have also been within an extensional basin but basin boundary faults have not yet been identified within the structural block below the pre-MBG unconformity. This basin developed above Laurentian crust previously thinned during late Protozoic rifting.

  3. Star Formation for Predictive Primordial Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Milosavljević, Miloš; Safranek-Shrader, Chalence

    The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here we review the current understanding of early star formation, emphasizing unsolved problems and technical challenges. We begin with the first generation of stars to form after the Big Bang and trace how they influenced subsequent star formation. The onset of chemical enrichment coincided with a sharp increase in the overall physical complexity of star forming systems. Ab-initio computational treatments are just now entering the domain of the predictive and are establishing contact with local observations of the relics of this ancient epoch.

  4. Bedrock geologic map of the Spring Valley, West Plains, and parts of the Piedmont and Poplar Bluff 30'x60' quadrangles, Missouri, including the upper Current River and Eleven Point River drainage basins

    USGS Publications Warehouse

    Weary, David J.; Harrison, Richard W.; Orndorff, Randall C.; Weems, Robert E.; Schindler, J. Stephen; Repetski, John E.; Pierce, Herbert A.

    2015-01-01

    Potentially economic mineral resources are present in the subsurface in the map area. Exploration drill-hole data indicate that anomalously high concentrations of base-metal sulfides locally occur within the Cambrian Bonneterre Formation. The geologic setting of these anomalous concentrations is similar to that found in the Viburnum Trend, part of the largest lead-mining district in the world. The southernmost part of the Viburnum Trend extends into the northern part of the map area and is exploited by the Sweetwater Mine. Undeveloped and potentially economic occurrences of base metals are known also beneath Blair Creek, a tributary to the Current River in the north-central part of the map area.

  5. Tropical cyclone formation

    SciTech Connect

    Montgomery, M.T.; Farrell, B.F. )

    1993-01-15

    The physics of tropical cyclone formation is not well understood, and more is known about the mature hurricane than the formative mechanisms that produce it. It is believed part of the reason for this can be traced to insufficient upper-level atmospheric data. Recent observations suggest that tropical cyclones are initiated by asymmetric interactions associated with migratory upper-level potential vorticity disturbances and low-level disturbances. Favored theories of cyclones formation, however, focus on internal processes associated with cumulus convection and/or air-sea interaction. This work focuses on external mechanisms of cyclone formation and, using both a two- and three-dimensional moist geostrophic momentum model, investigates the role of upper-level potential vorticity disturbances on the formation process. A conceptual model of tropical cyclone formation is proposed, and implications of the theory are discussed. 71 refs., 5 figs., 1 tab.

  6. Global Star Formation Revisited

    NASA Astrophysics Data System (ADS)

    Silk, Joseph; Norman, Colin

    2009-07-01

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  7. GLOBAL STAR FORMATION REVISITED

    SciTech Connect

    Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu

    2009-07-20

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  8. School Formative Feedback Systems

    ERIC Educational Resources Information Center

    Halverson, Richard

    2010-01-01

    Data-driven instructional improvement relies on developing coherent systems that allow school staff to generate, interpret, and act upon quality formative information on students and school programs. This article offers a formative feedback system model that captures how school leaders and teachers structure artifacts and practices to create

  9. Formative Assessment. Research Brief

    ERIC Educational Resources Information Center

    Walker, Karen

    2009-01-01

    There are many kinds of classroom assessment--from informal observation of students to more formal exams and standardized tests. Two categories have been identified--formative assessments and summative assessments. Formative assessments are used by teachers to provide feedback to students and to guide improvement of instruction. For example, if a

  10. Formative Assessment Probes

    ERIC Educational Resources Information Center

    Eberle, Francis; Keeley, Page

    2008-01-01

    Formative assessment probes can be effective tools to help teachers build a bridge between students' initial ideas and scientific ones. In this article, the authors describe how using two formative assessment probes can help teachers determine the extent to which students make similar connections between developing a concept of matter and a

  11. Formative Assessment Probes

    ERIC Educational Resources Information Center

    Eberle, Francis; Keeley, Page

    2008-01-01

    Formative assessment probes can be effective tools to help teachers build a bridge between students' initial ideas and scientific ones. In this article, the authors describe how using two formative assessment probes can help teachers determine the extent to which students make similar connections between developing a concept of matter and a…

  12. When Efficient Star Formation Drives Cluster Formation

    NASA Astrophysics Data System (ADS)

    Parmentier, G.; Fritze, U.

    2009-01-01

    We investigate the impact of the star-formation efficiency (SFE) in cluster-forming cores (i.e., local SFE) on the evolution of mass in star clusters (SCs) over the age range 1-100 Myr, when SCs undergo their infant weight-loss/mortality phase. Our model builds on the N-body simulation grid of Baumgardt & Kroupa. Assuming a constant formation rate of gas-embedded clusters and a weak tidal field, we show that the ratio between the total mass in stars bound to the clusters over that age range and the total mass in stars initially formed in gas-embedded clusters is a strongly increasing function of the averaged local SFE, with little influence from any assumed core mass-radius relation. Our results suggest that, for young starbursts with estimated tidal field strength and known recent star-formation history, observed cluster-to-star mass ratios, once corrected for the undetected clusters, constitute promising probes of the local SFE without the need to resort to gas mass estimates. Similarly, the mass ratio of stars that remain in bound clusters at the end of the infant mortality/weight-loss phase (i.e., age gsim50 Myr) depends sensitively on the mean local SFE, although the impacts of the width of the SFE distribution function and of the core mass-radius relation require more careful assessment in this case. Following the recent finding by Bastian that galaxies form, on average, 8% of their stars in bound clusters regardless of their star-formation rate, we raise the hypothesis that star formation in the present-day universe is characterized by a near-universal distribution of the local SFE. A related potential application of our model is in tracing the evolution of the local SFE over cosmological lookback times by comparing the age distribution of the total mass in SCs to that in field stars in galaxies where field stars can be resolved and age dated. We describe aspects of our model which are still to be worked out before this goal can be achieved.

  13. Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tan, J. C.; Beltrn, M. T.; Caselli, P.; Fontani, F.; Fuente, A.; Krumholz, M. R.; McKee, C. F.; Stolte, A.

    The enormous radiative and mechanical luminosities of massive stars impact a vast range of scales and processes, from the reionization of the universe, to the evolution of galaxies, to the regulation of the interstellar medium, to the formation of star clusters, and even to the formation of planets around stars in such clusters. Two main classes of massive star formation theory are under active study: core accretion and competitive accretion. In core accretion, the initial conditions are self-gravitating, centrally concentrated cores that condense with a range of masses from the surrounding, fragmenting clump environment. They then undergo relatively ordered collapse via a central disk to form a single star or a small-N multiple. In this case, the prestellar core mass function has a similar form to the stellar initial mass function. In competitive accretion, the material that forms a massive star is drawn more chaotically from a wider region of the clump without passing through a phase of being in a massive, coherent core. In this case, massive star formation must proceed hand in hand with star cluster formation. If stellar densities become very high near the cluster center, then collisions between stars may also help to form the most massive stars. We review recent theoretical and observational progress toward understanding massive star formation, considering physical and chemical processes, comparisons with low and intermediate-mass stars, and connections to star cluster formation.

  14. Sparse Image Format

    Energy Science and Technology Software Center (ESTSC)

    2007-04-12

    The Sparse Image Format (SIF) is a file format for storing spare raster images. It works by breaking an image down into tiles. Space is savid by only storing non-uniform tiles, i.e. tiles with at least two different pixel values. If a tile is completely uniform, its common pixel value is stored instead of the complete tile raster. The software is a library in the C language used for manipulating files in SIF format. Itmore » supports large files (> 2GB) and is designed to build in Windows and Linux environments.« less

  15. MARC Format Simplification.

    ERIC Educational Resources Information Center

    Gapen, D. Kaye

    1981-01-01

    Summarizes the feasibility of simplifying the MARC format for bibliographic records, including the benefits, disadvantages, and consequences. Five perspectives are given: history, standards, and codes; present purposes; computer operations; library operations; and online catalogs. There are four references. (RAA)

  16. Plant Formate Dehydrogenase

    SciTech Connect

    John Markwell

    2005-01-10

    The research in this study identified formate dehydrogenase, an enzyme that plays a metabolic role on the periphery of one-carbon metabolism, has an unusual localization in Arabidopsis thaliana and that the enzyme has an unusual kinetic plasticity. These properties make it possible that this enzyme could be engineered to attempt to engineer plants with an improved photosynthetic efficiency. We have produced transgenic Arabidopsis and tobacco plants with increased expression of the formate dehydrogenase enzyme to initiate further studies.

  17. Formation of Giant Planets

    NASA Technical Reports Server (NTRS)

    Lin, Douglas

    1999-01-01

    Under the support of NASA Origins grant, we studied the formation of gaps in protoplanetary disks due the tidal interaction between a fully grown protoplanet and protostellar disk. The result of this study is published in the Astrophysical Journal, (vol 514, 344-367, 1999) and in several conference proceedings. The main focus of this work is to analyze planet-disk interaction during the final stages of protoplanetary formation.

  18. Display formats manual

    NASA Technical Reports Server (NTRS)

    Runnels, R. L.

    1973-01-01

    The standards and procedures for the generation of operational display formats to be used in the Mission Control Center (MCC) display control system are presented. The required effort, forms, and fundamentals for the design, specifications, and production of display formats are identified. The principles of display design and system constraints controlling the creation of optimum operational displays for mission control are explained. The basic two types of MCC display systems for presenting information are described.

  19. Complex format synchronization and decommutation

    NASA Astrophysics Data System (ADS)

    Thom, Gary A.

    Some complex telemetry formats currently used for data transmission by airborn data acquisition systems are reviewed. The formats discussed include asynchronous embedded formats, tagged data formats, IRIG 106 Chapter 8 formats, multiplexed formats, and adaptive formats. The need for designing decommutation systems characterized by extended life or capable of supporting multiple applications that are flexible enough to adapt to new formats is emphasized. It is suggested that existing complex formats be used as a guide in designing new systems with flexibility for future applications.

  20. CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

    SciTech Connect

    Duane A. McVay; Walter B. Ayers Jr.; Jerry L. Jensen

    2003-10-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. The main objective for this reporting period was to further characterize the three areas selected as potential CO{sub 2} sequestration sites. Well-log data are critical for defining depth, thickness, number, and grouping of coal seams at the proposed sequestration sites. Thus, we purchased 12 hardcopy well logs (in addition to 15 well logs obtained during previous quarter) from a commercial source and digitized them to make coal-occurrence maps and cross sections. Detailed correlation of coal zones is important for reservoir analysis and modeling. Thus, we correlated and mapped Wilcox Group subdivisions--the Hooper, Simsboro and Calvert Bluff formations, as well as the coal-bearing intervals of the Yegua and Jackson formations in well logs. To assess cleat properties and describe coal characteristics, we made field trips to Big Brown and Martin Lake coal mines. This quarter we also received CO{sub 2} and methane sorption analyses of the Sandow Mine samples, and we are assessing the results. GEM, a compositional simulator developed by the Computer Modeling Group (CMG), was selected for performing the CO{sub 2} sequestration and enhanced CBM modeling tasks for this project. This software was used to conduct preliminary CO{sub 2} sequestration and methane production simulations in a 5-spot injection pattern. We are continuing to pursue a cooperative agreement with Anadarko Petroleum, which has already acquired significant relevant data near one of our potential sequestration sites.

  1. Positronium Formation in Muscle

    PubMed Central

    Gustafson, D. R.

    1970-01-01

    Positronium formation in muscle at +4°C and -4°C was examined by the measurement of the angular correlation of positron annihilation radiation. Since the positronium formation rate in ice is considerably higher than it is in water, there should be a comparable increase in the positronium formation rate in muscle tissue if recent speculation that cellular water is ordered in a semicrystalline icelike state is correct. Comparison of the angular correlation from muscle at +4°C with that from water at +4°C shows no enhancement of the positronium formation rate. Frozen muscle at -4°C shows an enhancement of the positronium formation rate of approximately half that found in ice at -4°C, indicating that most cellular water undergoes a normal water-ice transition when frozen. It is concluded therefore that cell water in muscle is not ordered in a hexagonal icelike structure. While the results are consistent with the hypothesis that cell water is in the liquid state, the hypothesis that cell water is ordered in an undetermined close packed structure which transforms to the hexagonal ice structure at or near 0°C cannot be ruled out. PMID:5436881

  2. Vascular Lumen Formation

    PubMed Central

    Lammert, Eckhard; Axnick, Jennifer

    2012-01-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cellcell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved. PMID:22474612

  3. Isolating Triggered Star Formation

    SciTech Connect

    Barton, Elizabeth J.; Arnold, Jacob A.; Zentner, Andrew R.; Bullock, James S.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

    2007-09-12

    Galaxy pairs provide a potentially powerful means of studying triggered star formation from galaxy interactions. We use a large cosmological N-body simulation coupled with a well-tested semi-analytic substructure model to demonstrate that the majority of galaxies in close pairs reside within cluster or group-size halos and therefore represent a biased population, poorly suited for direct comparison to 'field' galaxies. Thus, the frequent observation that some types of galaxies in pairs have redder colors than 'field' galaxies is primarily a selection effect. We use our simulations to devise a means to select galaxy pairs that are isolated in their dark matter halos with respect to other massive subhalos (N= 2 halos) and to select a control sample of isolated galaxies (N= 1 halos) for comparison. We then apply these selection criteria to a volume-limited subset of the 2dF Galaxy Redshift Survey with M{sub B,j} {le} -19 and obtain the first clean measure of the typical fraction of galaxies affected by triggered star formation and the average elevation in the star formation rate. We find that 24% (30.5 %) of these L* and sub-L* galaxies in isolated 50 (30) h{sup -1} kpc pairs exhibit star formation that is boosted by a factor of {approx}> 5 above their average past value, while only 10% of isolated galaxies in the control sample show this level of enhancement. Thus, 14% (20 %) of the galaxies in these close pairs show clear triggered star formation. Our orbit models suggest that 12% (16%) of 50 (30) h{sup -1} kpc close pairs that are isolated according to our definition have had a close ({le} 30 h{sup -1} kpc) pass within the last Gyr. Thus, the data are broadly consistent with a scenario in which most or all close passes of isolated pairs result in triggered star formation. The isolation criteria we develop provide a means to constrain star formation and feedback prescriptions in hydrodynamic simulations and a very general method of understanding the importance of triggered star formation in a cosmological context.

  4. Gaussian entanglement of formation

    SciTech Connect

    Wolf, M.M.; Giedke, G.; Krueger, O.; Werner, R. F.; Cirac, J.I.

    2004-05-01

    We introduce a Gaussian version of the entanglement of formation adapted to bipartite Gaussian states by considering decompositions into pure Gaussian states only. We show that this quantity is an entanglement monotone under Gaussian operations and provide a simplified computation for states of arbitrary many modes. For the case of one mode per site the remaining variational problem can be solved analytically. If the considered state is in addition symmetric with respect to interchanging the two modes, we prove additivity of the considered entanglement measure. Moreover, in this case and considering only a single copy, our entanglement measure coincides with the true entanglement of formation.

  5. Ultrarelativistic black hole formation

    NASA Astrophysics Data System (ADS)

    East, William; Pretorius, Frans

    2013-04-01

    A topic in general relativity that remains poorly understood is the formation of black holes in ultrarelativistic collisions. Besides being an interesting theoretical question, it has been suggested that this may occur in the collision of cosmic rays with the Earth's atmosphere and in proton collisions at the LHC, in scenarios where large extra dimensions set the true Planck scale at around a TeV. We present results from numerical simulations of the head-on collision of equal mass particles, modeled as self-gravitating fluid spheres, obtained by solving the Einstein equations coupled to hydrodynamics. We focus on cases well within the kinetic energy dominated regime (?=8 to 12) and find that black hole formation does occur for sufficiently large boosts. Moreover, near yet above the threshold of black hole formation, the collision initially leads to the formation of two distinct apparent horizons that subsequently merge. We argue that this can be understood in terms of a focusing effect, where one boosted particle acts as a gravitational lens on the other and vice versa, and that this is further responsible for the threshold being lower (by a factor of a few) compared to simple hoop conjecture estimate.

  6. Bacterial formate hydrogenlyase complex

    PubMed Central

    McDowall, Jennifer S.; Murphy, Bonnie J.; Haumann, Michael; Palmer, Tracy; Armstrong, Fraser A.; Sargent, Frank

    2014-01-01

    Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics, maturation, and some biochemistry of FHL are understood, the protein complex has never been isolated in an intact form to allow biochemical analysis. In this work, genetic tools are reported that allow the facile isolation of FHL in a single chromatographic step. The core complex is shown to comprise HycE (a [NiFe] hydrogenase component termed Hyd-3), FdhF (the molybdenum-dependent formate dehydrogenase-H), and three iron-sulfur proteins: HycB, HycF, and HycG. A proportion of this core complex remains associated with HycC and HycD, which are polytopic integral membrane proteins believed to anchor the core complex to the cytoplasmic side of the membrane. As isolated, the FHL complex retains formate hydrogenlyase activity in vitro. Protein film electrochemistry experiments on Hyd-3 demonstrate that it has a unique ability among [NiFe] hydrogenases to catalyze production of H2 even at high partial pressures of H2. Understanding and harnessing the activity of the FHL complex is critical to advancing future biohydrogen research efforts. PMID:25157147

  7. The Formation of Trihalomethanes.

    ERIC Educational Resources Information Center

    Trussell, R. Rhodes; Umphres, Mark D.

    1978-01-01

    Reviewed are a number of factors important in the formation of trihalomethanes (THM) including the nature of aquatic humus and the influences of preozonation, bromide, pH, and chlorine. A brief investigation is also conducted into the kinetics of the THM reaction. Several major research needs are represented. (CS)

  8. Carrascolendas: A Formative Evaluation.

    ERIC Educational Resources Information Center

    Laosa, Luis M.

    A formative research project sought to test viewer reactions to two pilot programs of the Carrascolendas series. A total of 360 Puerto Rican-American, Cuban-American, Mexican-American, and Anglo-American children in grades 1, 2, and 3 were observed as they watched the programs. Results indicated that there was high eye contact during the…

  9. Kepler Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2015-01-01

    Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

  10. Formation of planetesimals

    NASA Technical Reports Server (NTRS)

    Weidenschilling, Stuart J.

    1991-01-01

    Formation of planetesimals is discussed. The following subject areas are covered: (1) nebular structure; (2) aerodynamics of the solid bodies in the nebula; (3) problems with gravitational instability; (4) particle growth by coagulation; properties of fractal aggregates; and (5) coagulation and settling of fractal aggregates.

  11. Queen's Garden Formations

    USGS Multimedia Gallery

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  12. FORMATION OF PHOTOCHEMICAL AEROSOLS

    EPA Science Inventory

    The objective was to develop a better understanding of smog aerosol formation with particular reference to haze in the Southern California area. This study combined laboratory work with ambient air studies. Counting of particles by light scattering was the principle physical tech...

  13. Formation in the Classroom

    ERIC Educational Resources Information Center

    Glennon, Fred; Jacobsen, Douglas; Jacobsen, Rhonda Hustedt; Thatamanil, John J.; Porterfield, Amanda; Moore, Mary Elizabeth

    2011-01-01

    What is the relationship between the academic knowledge of the guild and the formation of students in the classroom? This Forum gathers four essays originally presented at a Special Topics Session at the 2009 conference of the American Academy of Religion (Atlanta, Georgia), with a brief introductory essay by Fred Glennon explaining the genesis of…

  14. Technobabble: File Formats.

    ERIC Educational Resources Information Center

    Wilson, Bradley

    1999-01-01

    Considers the confusion of over 20 different kinds of graphics programs. Briefly distinguishes between some of the more popular graphics formats (Photoshop, TIFF, JPEG, GIF, PICT, and EPS), and describes the benefits and disadvantages of each in the context of journalism education. (SC)

  15. Alternative fuel deposit formation

    SciTech Connect

    TeVelde, J.; Spadaccini, L.J.; Szetela, E.J.; Glickstein, M.R.

    1984-01-01

    A heated-tube apparatus was used to evaluate the deposit formation rates of four liquid hydrocarbon fuels and to determine the effect fuel deposits have on the heat transfer characteristics of aircraft gas turbine fuel systems. The fuels tested were: a low- aromatic JP-5, a blend of 80 percent JP-5 20 percent hydrocracked gas oil, a blend of 50 percent JP-5 and 50 percent No. 2 heating oil, and a shale derived JP-5. Deposit formation rates ranging from 10 microgram/sq cm hr to 3000 microgram/sq cm hr were obtained at tube wall temperatures ranging from 480 K to 800 K, with peak formation rates occurring at initial surface temperatures of 644 K to 672 K. Results indicate that deposit formation rate correlates very well with initial surface temperature and the thermal stability rankings derived from present experimental results agree very well with rankings based upon independent JFTOT analysis. The deposit thermal resistance, as calculated from heat transfer measurements, correlates well with measured deposit quantity and thickness. Heat transfer analyses indicate that the deposit thermal conductivity increases with increasing deposit thickness, and ranges from values approximating the thermal conductivity of the fuel to values approaching that of amorphous carbon.

  16. Formation in the Classroom

    ERIC Educational Resources Information Center

    Glennon, Fred; Jacobsen, Douglas; Jacobsen, Rhonda Hustedt; Thatamanil, John J.; Porterfield, Amanda; Moore, Mary Elizabeth

    2011-01-01

    What is the relationship between the academic knowledge of the guild and the formation of students in the classroom? This Forum gathers four essays originally presented at a Special Topics Session at the 2009 conference of the American Academy of Religion (Atlanta, Georgia), with a brief introductory essay by Fred Glennon explaining the genesis of

  17. Generic file format

    NASA Astrophysics Data System (ADS)

    Felgate, Nick

    2002-11-01

    The Generic File Format (GFF) is a file format developed within the UK ASW community for the interchange and storage of underwater sonar data. Originally developed for the interchange of time-series data between analysis systems, it has been extended to provide for storage of processed acoustic data (e.g., power and DEMON spectrum, lofargram grey-scale), nonacoustic data (e.g., own-ship dynamics, sensor configuration) and event data (e.g., tracker output, sonar intercepts). The format employs the chunk concept, as used in the WAV and AIFF file formats, to provide extendability (including local variants) while providing a measure of backward compatability. However, the basic concept has been adapted to allow for the mixing in the one file of multiple channels of different sample-rates and data-types through the inclusion of a data frame concept and multiple data blocks. Chunk cross-referencing has been employed to ensure data consistency. A provision is made in the header of the file to store details of the sensor and processing for the data (e.g., the number of hydrophones, beam direction, FFT size) so that an analysis system does not need to know about the sensor or other system from which the data originated.

  18. Pattern formation today

    PubMed Central

    Chuong, Cheng-Ming; Richardson, Michael K.

    2010-01-01

    Patterns are orders embedded in randomness. They may appear as spatial arrangements or temporal series, and the elements may appear identical or with variations. Patterns exist in the physical world as well as in living systems. In the biological world, patterns can range from simple to complex, forming the basic building blocks of life. The process which generates this ordering in the biological world was termed pattern formation. Since Wolpert promoted this concept four decades ago, scientists from molecular biology, developmental biology, stem cell biology, tissue engineering, theoretical modeling and other disciplines have made remarkable progress towards understanding its mechanisms. It is time to review and re-integrate our understanding. Here, we explore the origin of pattern formation, how the genetic code is translated into biological form, and how complex phenotypes are selected over evolutionary time. We present four topics: Principles, Evolution, Development, and Stem Cells and Regeneration. We have interviewed several leaders in the field to gain insight into how their research and the field of pattern formation have shaped each other. We have learned that both molecular process and physico-chemical principles are important for biological pattern formation. New understanding will emerge through integration of the analytical approach of molecular-genetic manipulation and the systemic approach of model simulation. We regret that we could not include every major investigator in the field, but hope that this Special Issue of the Int. J. Dev. Biol. represents a sample of our knowledge of pattern formation today, which will help to stimulate more research on this fundamental process. PMID:19557673

  19. Mansion on the Bluff Catches Lives on the Edge.

    ERIC Educational Resources Information Center

    Priem, Shannon

    1998-01-01

    Describes Open Meadow Learning Center (Portland, Oregon), a private alternative high school with a long waiting list and a probationary period for new students. School features include an advocacy role for teachers that strengthens teacher/student relationships, 80% attendance requirement, safe and supportive environment, environmental

  20. Atmospheric flow over two-dimensional bluff surface obstructions

    NASA Technical Reports Server (NTRS)

    Bitte, J.; Frost, W.

    1976-01-01

    The phenomenon of atmospheric flow over a two-dimensional surface obstruction, such as a building (modeled as a rectangular block, a fence or a forward-facing step), is analyzed by three methods: (1) an inviscid free streamline approach, (2) a turbulent boundary layer approach using an eddy viscosity turbulence model and a horizontal pressure gradient determined by the inviscid model, and (3) an approach using the full Navier-Stokes equations with three turbulence models; i.e., an eddy viscosity model, a turbulence kinetic-energy model and a two-equation model with an additional transport equation for the turbulence length scale. A comparison of the performance of the different turbulence models is given, indicating that only the two-equation model adequately accounts for the convective character of turbulence. Turbulence flow property predictions obtained from the turbulence kinetic-energy model with prescribed length scale are only insignificantly better than those obtained from the eddy viscosity model. A parametric study includes the effects of the variation of the characteristics parameters of the assumed logarithmic approach velocity profile. For the case of the forward-facing step, it is shown that in the downstream flow region an increase of the surface roughness gives rise to higher turbulence levels in the shear layer originating from the step corner.

  1. Bluff-body drag reduction by passive ventilation

    NASA Astrophysics Data System (ADS)

    Suryanarayana, G. K.; Pauer, Henning; Meier, G. E. A.

    1993-12-01

    The drag of a sphere at high Re can be reduced to more than half its value by passive ventilation from the stagnation region to the base. Simultaneously, the flow field around the base is stabilized and made symmetric, leading to reduction of unsteady aerodynamic forces. At high Re, the vent flow breaks through the dead water region associated with the near wake and aerodynamically streamlines the base. The streamlining is done by virtue of a base-vortex-ring beyond the point of turbulent boundary layer separation. A mean flow model for the flow around the vented sphere is proposed. Smoke flow visualized on a laser light screen placed at two diameters behind the base of the sphere shows the effectiveness of the method in suppressing the flow oscillations. The drag reduction achieved is very sensitive to the quality of the external surface and relatively insensitive to disturbances in the internal flow. Surface roughness or boundary layer tripping wire on the external flow can completely offset the benefit obtained.

  2. Simulations of Bluff Body Flow Interaction for Noise Source Modeling

    NASA Technical Reports Server (NTRS)

    Khorrami, Medi R.; Lockard David P.; Choudhari, Meelan M.; Jenkins, Luther N.; Neuhart, Dan H.; McGinley, Catherine B.

    2006-01-01

    The current study is a continuation of our effort to characterize the details of flow interaction between two cylinders in a tandem configuration. This configuration is viewed to possess many of the pertinent flow features of the highly interactive unsteady flow field associated with the main landing gear of large civil transports. The present effort extends our previous two-dimensional, unsteady, Reynolds Averaged Navier-Stokes computations to three dimensions using a quasilaminar, zonal approach, in conjunction with a two-equation turbulence model. Two distinct separation length-to-diameter ratios of L/D = 3.7 and 1.435, representing intermediate and short separation distances between the two cylinders, are simulated. The Mach 0.166 simulations are performed at a Reynolds number of Re = 1.66 105 to match the companion experiments at NASA Langley Research Center. Extensive comparisons with the measured steady and unsteady surface pressure and off-surface particle image velocimetry data show encouraging agreement. Both prominent and some of the more subtle trends in the mean and fluctuating flow fields are correctly predicted. Both computations and the measured data reveal a more robust and energetic shedding process at L/D = 3.7 in comparison with the weaker shedding in the shorter separation case of L/D = 1.435. The vortex shedding frequency based on the computed surface pressure spectra is in reasonable agreement with the measured Strouhal frequency.

  3. Bluff Body Flow Simulation Using a Vortex Element Method

    SciTech Connect

    Anthony Leonard; Phillippe Chatelain; Michael Rebel

    2004-09-30

    Heavy ground vehicles, especially those involved in long-haul freight transportation, consume a significant part of our nation's energy supply. it is therefore of utmost importance to improve their efficiency, both to reduce emissions and to decrease reliance on imported oil. At highway speeds, more than half of the power consumed by a typical semi truck goes into overcoming aerodynamic drag, a fraction which increases with speed and crosswind. Thanks to better tools and increased awareness, recent years have seen substantial aerodynamic improvements by the truck industry, such as tractor/trailer height matching, radiator area reduction, and swept fairings. However, there remains substantial room for improvement as understanding of turbulent fluid dynamics grows. The group's research effort focused on vortex particle methods, a novel approach for computational fluid dynamics (CFD). Where common CFD methods solve or model the Navier-Stokes equations on a grid which stretches from the truck surface outward, vortex particle methods solve the vorticity equation on a Lagrangian basis of smooth particles and do not require a grid. They worked to advance the state of the art in vortex particle methods, improving their ability to handle the complicated, high Reynolds number flow around heavy vehicles. Specific challenges that they have addressed include finding strategies to accurate capture vorticity generation and resultant forces at the truck wall, handling the aerodynamics of spinning bodies such as tires, application of the method to the GTS model, computation time reduction through improved integration methods, a closest point transform for particle method in complex geometrics, and work on large eddy simulation (LES) turbulence modeling.

  4. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 10 April 2002) The Science This THEMIS visible image was acquired near 7o S, 172o W (188o E) and shows a remarkable martian geologic deposit known as the Medusae Fossae Formation. This Formation, seen here as the raised plateau in the upper two-thirds of the image, is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region the deposit has been heavily eroded by the wind to produce a series of linear ridges called yardangs. These parallel ridges point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to sculpt the dry landscape of Mars. The Medusae Fossae Formation has been completely stripped from the surface in the lower third of the image, revealing a harder layer below that is more resistant to wind erosion. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Several ancient craters that were once completely buried by this deposit are being exposed, or exhumed, as the overlying Medusae Formation is removed. Very few impact craters are visible on this Formation, indicating that the surface seen today is relatively young, and that the processes of erosion are likely to be actively occurring. The Story Medusa of Greek mythology fame, the name-giver to this region, had snaky locks of hair that could turn a person to stone. Wild and unruly, this monster of the underworld could certainly wreak havoc on the world of the human imagination. As scary as she was, Medusa would have no advantage over the fierce, masterful winds blowing across Mars, which once carved the streaky, terrain at the top of this image. Wild and whipping, these winds have slowly eroded away the 'topsoil,' revealing ancient craters and other surface features they once covered. The loosely cemented particles of this 'topsoil' are likely made up of dust or volcanic ash, and are thus more susceptible to windblown erosion. The Martian winds have actually been strong and relentless enough over time to strip the land in the bottom of this image of the material that once covered it, leaving it hard and bare to the eye.

  5. Cosmic structure formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edumund

    1994-01-01

    This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most detailed investigations of structure formation. The observed univers approaches spatial uniformity on scales larger than about 10(exp 26) cm. On these scales gravitational dynamics is almost linear and therefore relatively easy to relate to observations of large-scale structure. On smaller scales cosmic structure is complicated not only by nonlinear gravitational clustering but also by nonlinear nongravitational gas dynamical processes. The complexity of these phenomena makes galaxy formation one of the grand challenge problems of the physical sciences. No fully satisfactory theory can presently account in detail for the observed cosmic structure. However, as this article summarizes, significant progress has been made during the last few years.

  6. Prominence Formation Processes

    NASA Astrophysics Data System (ADS)

    Welsch, B. T.; DeVore, C. R.; Antiochos, S. K.

    2005-01-01

    Martens and Zwaan (ApJ v. 558 872) have proposed a prominence/ filament formation model in which differential rotation drives reconnection between two initially unconnected active regions to form helical field lines that support mass and are held down by overlying field. Using an MHD solver with adaptive refinement we simulated this process by imposing a shear flow meant to mimic differential rotation on two bipolar flux distributions meant to mimic distinct active regions. In some runs the flux systems are initially potential while in others they have been twisted by footpoint rotation to inject helicity prior to imposing the shear flow. The resulting structures are studied to understand the role of helicity in the formation of prominence-like structures.

  7. Cosmological structure formation

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1991-01-01

    A summary of the current forefront problem of physical cosmology, the formation of structures (galaxies, clusters, great walls, etc.) in the universe is presented. Solutions require two key ingredients: (1) matter; and (2) seeds. Regarding the matter, it now seems clear that both baryonic and non-baryonic matter are required. Whether the non-baryonic matter is hot or cold depends on the choice of seeds. Regarding the seeds, both density fluctuations and topological defects are discussed. The combination of isotropy of the microwave background and the recent observations indicating more power on large scales have severly constrained, if not eliminated, Gaussian fluctuations with equal power on all scales, regardless of the eventual resolution of both the matter and seed questions. It is important to note that all current structure formation ideas require new physics beyond SU(3) x SU(2) x U(1).

  8. Moment formation in solids

    SciTech Connect

    Buyers, W.J.L.

    1984-01-01

    The problem of moment formation in metallic systems lies at the interface of localized and itinerant magnetism. The phenomena observed correspond to destruction rather than to formation of spin-correlations. They give rise to the progression from localized ground states through Kondo and mixed-valence behavior to itinerant magnetic or non-magnetic systems. Somewhere in the progression superconductivity can occur in the presence of f-moments. This conference presents information on the following topics: neuron inelastic scattering as a probe of moments in metallic systems; cyclotron resonance and relaxation of hot charge carriers; orbital effects in actinide systems; theory of elementary excitations in intermediate valence materials: phenomena involving magnetic moment suppresion; and superconducting ground state of a strongly interacting electron system: UBe/sub 13/.

  9. Format( )MEDIC( )Input

    NASA Astrophysics Data System (ADS)

    Foster, K.

    1994-09-01

    This document is a description of a computer program called Format( )MEDIC( )Input. The purpose of this program is to allow the user to quickly reformat wind velocity data in the Model Evaluation Database (MEDb) into a reasonable 'first cut' set of MEDIC input files (MEDIC.nml, StnLoc.Met, and Observ.Met). The user is cautioned that these resulting input files must be reviewed for correctness and completeness. This program will not format MEDb data into a Problem Station Library or Problem Metdata File. A description of how the program reformats the data is provided, along with a description of the required and optional user input and a description of the resulting output files. A description of the MEDb is not provided here but can be found in the RAS Division Model Evaluation Database Description document.

  10. PKCs in thrombus formation.

    PubMed

    Zaid, Y; Senhaji, N; Naya, A; Fadainia, C; Kojok, K

    2015-12-01

    The protein kinase C (PKC) family has been implicated in several physiological processes regulating platelet activation. Each isoform of PKC expressed on platelets, may have a positive and/or negative role depending on the nature and concentration of the agonist. Mice lacking PKC? show much reduced thrombus formation in vivo, while PKC?(-/-) showed inhibition of aggregation in response to PAR4. On the other hand, PKC? by associating with Fyn, inhibits platelet aggregation. In addition, PKC? by interacting with its receptor RACK1 has been implicated in the primary phases of signaling via the ?IIb?3 and finally PKC? appears to be involved in platelet function downstream GPVI. The present review discusses the latest observations relevant to the role of individual PKC isoforms in platelet activation and thrombus formation. PMID:26476932

  11. Format-Preserving Encryption

    NASA Astrophysics Data System (ADS)

    Bellare, Mihir; Ristenpart, Thomas; Rogaway, Phillip; Stegers, Till

    Format-preserving encryption (FPE) encrypts a plaintext of some specified format into a ciphertext of identical format—for example, encrypting a valid credit-card number into a valid credit-card number. The problem has been known for some time, but it has lacked a fully general and rigorous treatment. We provide one, starting off by formally defining FPE and security goals for it. We investigate the natural approach for achieving FPE on complex domains, the “rank-then-encipher” approach, and explore what it can and cannot do. We describe two flavors of unbalanced Feistel networks that can be used for achieving FPE, and we prove new security results for each. We revisit the cycle-walking approach for enciphering on a non-sparse subset of an encipherable domain, showing that the timing information that may be divulged by cycle walking is not a damaging thing to leak.

  12. Formation of bacterial nanocells

    NASA Astrophysics Data System (ADS)

    Vainshtein, Mikhail; Kudryashova, Ekaterina; Suzina, Natalia; Ariskina, Elena; Voronkov, Vadim

    1998-07-01

    Existence of nanobacteria received increasing attention both in environmental microbiology/geomicro-biology and in medical microbiology. In order to study a production of nanoforms by typical bacterial cells. Effects of different physical factors were investigated. Treatment of bacterial cultures with microwave radiation, or culturing in field of electric current resulted in formation a few types of nanocells. The number and type of nanoforms were determined with type and dose of the treatment. The produced nanoforms were: i) globules, ii) clusters of the globules--probably produced by liaison, iii) nanocells coated with membrane. The viability of the globules is an object opened for doubts. The nanocells discovered multiplication and growth on solidified nutrient media. The authors suggest that formation of nanocells is a common response of bacteria to stress-actions produced by different agents.

  13. Tetrahedron Formation Control

    NASA Technical Reports Server (NTRS)

    Petruzzo, Charles; Guzman, Jose

    2004-01-01

    This paper considers the preliminary development of a general optimization procedure for tetrahedron formation control. The maneuvers are assumed to be impulsive and a multi-stage optimization method is employed. The stages include (1) targeting to a fixed tetrahedron location and orientation, and (2) rotating and translating the tetrahedron. The number of impulsive maneuvers can also be varied. As the impulse locations and times change, new arcs are computed using a differential corrections scheme that varies the impulse magnitudes and directions. The result is a continuous trajectory with velocity discontinuities. The velocity discontinuities are then used to formulate the cost function. Direct optimization techniques are employed. The procedure is applied to the NASA Goddard Magnetospheric Multi-Scale (MMS) mission to compute preliminary formation control fuel requirements.

  14. Hail Formation in Florida

    NASA Astrophysics Data System (ADS)

    Stanley, Matthew

    Hail poses a substantial threat to life and property in the state of Florida. These losses could be minimized through better understanding of the relationships between atmospheric variables that impact hail formation in Florida. Improving hail forecasting in Florida requires analyzing a number of meteorological parameters and synoptic data related to hail formation. NOAA archive data was retrieved to create a database that was used to categorize text files of hail days. The text files were entered into the National Oceanic and Atmospheric Administration Earth System Research Laboratory website to create National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis maps of atmospheric variables for Florida hail days as well as days leading to the hail event. These data were then analyzed to determine the relationship between variables that affect hail formation, in general, across different regions and seasons in Florida using Statistical Product and Service Solutions. The reasoning for the differing factors affecting hail formation between regions, seasons and hail sizes were discussed, as well as forecasting suggestions relating to region and month in Florida. The study found that the majority of all hail that occurs in Florida is during the wet season. A low Lifted Index, high Precipitable Water and lower than average Sea Level Pressure, in most cases, is present during hail days in Florida. Furthermore, results show that Vector Wind magnitude increases as hail size increases. Additionally, several atmospheric variables useful to studying hail events, such as Lifted Index, Precipitable Water, Sea Level Pressure, Vector Wind and Temperature have significant correlations with each other depending on the region and season being observed. Strong correlations between low Lifted Index, high Precipitable Water values and the occurrence of hail events are discussed, as well as the relationship between temperature anomalies at various pressure levels and the occurrence of hail events.

  15. Formate-assisted pyrolysis

    DOEpatents

    DeSisto, William Joseph; Wheeler, Marshall Clayton; van Heiningen, Adriaan R. P.

    2015-03-17

    The present invention provides, among other thing, methods for creating significantly deoxygenated bio-oils form biomass including the steps of providing a feedstock, associating the feedstock with an alkali formate to form a treated feedstock, dewatering the treated feedstock, heating the dewatered treated feedstock to form a vapor product, and condensing the vapor product to form a pyrolysis oil, wherein the pyrolysis oil contains less than 30% oxygen by weight.

  16. Formation of Transient Lamellipodia

    PubMed Central

    Zimmermann, Juliane; Falcke, Martin

    2014-01-01

    Cell motility driven by actin polymerization is pivotal to the development and survival of organisms and individual cells. Motile cells plated on flat substrates form membrane protrusions called lamellipodia. The protrusions repeatedly appear and retract in all directions. If a lamellipodium is stabilized and lasts for some time, it can take over the lead and determine the direction of cell motion. Protrusions traveling along the cell perimeter have also been observed. Their initiation is in some situations the effect of the dynamics of the pathway linking plasma membrane receptors to actin filament nucleation, e.g. in chemotaxis. However, lamellipodia are also formed in many cells incessantly during motion with a constant state of the signaling pathways upstream from nucleation promoting factors (NPFs), or spontaneously in resting cells. These observations strongly suggest protrusion formation can also be a consequence of the dynamics downstream from NPFs, with signaling setting the dynamic regime but not initiating the formation of individual protrusions. A quantitative mechanism for this kind of lamellipodium dynamics has not been suggested yet. Here, we present a model exhibiting excitable actin network dynamics. Individual lamellipodia form due to random supercritical filament nucleation events amplified by autocatalytic branching. They last for about 30 seconds to many minutes and are terminated by filament bundling, severing and capping. We show the relevance of the model mechanism for experimentally observed protrusion dynamics by reproducing in very good approximation the repetitive protrusion formation measured by Burnette et al. with respect to the velocities of leading edge protrusion and retrograde flow, oscillation amplitudes, periods and shape, as well as the phase relation between protrusion and retrograde flow. Our modeling results agree with the mechanism of actin bundle formation during lamellipodium retraction suggested by Burnette et al. and Koestler et al. PMID:24505300

  17. Mesospheric cloud formations

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1980-01-01

    Formation of mesospheric clouds as a result of deposition of large amounts of H2O by the heavy lift launch vehicle (HLLV) of the solar power satellite system is discussed. The conditions which must be met in order to form and maintain clouds near the mesopause are described. The frequency and magnitude of H2O injections from the HLLV rocket exhaust are considered.

  18. Chemistry of planet formation

    NASA Astrophysics Data System (ADS)

    Robinson, Sarah Elaine

    2008-02-01

    This thesis explores how the chemical environment in which planets develop influences planet formation. The total solid mass, gas/solid ratio, and specific ice inventory of protoplanetary disks can dramatically alter the planet's formation timescale, core/atmosphere mass ratio, and atmosphere composition. We present the results of three projects that probe the links between solar nebula composition and giant planet formation. The first project offers evidence that stars with planets exhibit statistically significant silicon and nickel enrichment over the general metal-rich population. To test whether this prediction is compatible with the core accretion theory of planet formation, we construct new numerical simulations of planet formation by core accretion that establish the timescale on which a planet forming at 5 AU reaches rapid gas accretion, t rga , as a function of solid surface density s solid : ( t rga /1 Myr) = (s solid /25.0 g cm -2 ) - 1.44 . This relation enables us to construct Monte Carlo simulations that predict the fraction of star-disk systems that form planets as a function of [Fe/H], [Si/Fe], disk mass, outer disk radius and disk lifetime. Our simulations reproduce both the known planet-metallicity correlation and the planet-silicon correlation reported in this paper. The simulations predict that 15% of Solar-type stars form Jupiter-mass planets, in agreement with 12% predicted from extrapolation of the observed planet frequency-semimajor axis distribution. Despite the success of our Monte Carlo simulation of the planet-silicon correlation at predicting the properties of extrasolar Jovian planets, there is still no in situ core accretion simulation that can successfully account for the formation of Saturn, Uranus or Neptune within the observed 2-3 Myr lifetimes of protoplanetary disks. Since solid accretion rate is directly proportional to the available planetesimal surface density, one way to speed up planet formation is to take a full inventory of all the solids present in the solar nebula. In Project 2 (Chapter 3) we combine a viscously evolving protostellar disk with a kinetic model of ice formation, which includes not just water but methane, ammonia, CO and 54 minor ices. We use this combined dynamical+chemical simulation to calculate the planetesimal composition and solid surface density in the solar nebula as a function of heliocentric distance and time. We find three effects that strongly favor giant planet formation: (1) a decretion flow that brings mass from the inner solar nebula to the giant planet-forming region, (2) recent lab results (Collings et al. 2004) showing that the ammonia and water ice lines should coincide, and (3) the presence of a substantial amount of methane ice in the trans-Saturnian region. Our results show higher solid surface densities than assumed in the core accretion models of Pollack et al. (1996) by a factor of 3-4 throughout the trans-Saturnian region. We also discuss the location of ice lines and their movement through the solar nebula, and provide new constraints on the possible initial disk configurations from gravitational stability arguments. Finally, we present a core accretion simulation of Saturn with a planet formation timescale of 3.37 Myr, consistent with observed protostellar disk lifetimes. The protostellar disk model underlying this simulation is also capable of forming Jupiter within 2.5 Myr. We observe a new manifestation of the core accretion theory, in which Saturn's solid core does not reach isolation mass, and argue that this paradigm should apply to Uranus and Neptune as well. The planet formation timescale is then governed primarily by the solid accretion rate instead of the gas contraction efficiency. Our model predicts a core mass of 44 M (+) for Saturn, heavier than inferred from observations by a factor of at least 2. We discuss possible mechanisms for reducing the core size without slowing down formation and comment on the similarity between our core- heavy Saturn model and the exoplanet HD 149026 b .

  19. Mars brine formation experiment

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Bullock, Mark A.; Stoker, Carol R.

    1992-01-01

    Evaporites, particularly carbonates, nitrates, and sulfates, may be major sinks of volatiles scavenged from the martian atmosphere. Mars is thought to have once had a denser, warmer atmosphere that permitted the presence of liquid surface water. The conversion of atmospheric CO2 into carbonate is hypothesized to have degraded the martian climate to its present state of a generally subfreezing, desiccated desert. The rate for such a conversion under martian conditions is poorly known, so the time scale of climate degradation by this process cannot be easily evaluated. If some models are correct, carbonate formation may have been fast at geological time scales. The experiments of Booth and Kieffer also imply fast (10(exp 6) - 10(exp 7) yr) removal of the missing CO2 inventory, estimated to be 1 - 5 bar, by means of carbonate formation. The timing of formation of many of the fluvial features observed on Mars is, in large part, dependent on when and how fast the atmosphere changed. A knowledge of the rate at which carbonates and nitrates formed is also essential for assessing the probability that life, or its chemical precursors, could have developed on Mars. No previous experiments have quantitatively evaluated the rate of solution for a suite of mobile anions and cations from unaltered minerals and atmospheric gases into liquid water under Mars-like conditions. Such experiments are the focus of this task.

  20. Terrestrial planet formation.

    PubMed

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  1. Ribbed moraine formation

    NASA Astrophysics Data System (ADS)

    Httestrand, Clas; Kleman, Johan

    Ribbed (Rogen) moraines are conspicuous landforms found in interior parts of formerly glaciated areas. Two major theories for ribbed moraine formation have been suggested in recent years: (i) the shear and stack theory, which explains ribbed moraine formation by shearing and stacking of till slabs or englacially entrained material during compressive flow, followed by basal melt-out of transverse moraine ridges, and (ii) the fracturing theory, according to which ribbed moraines form by fracturing of frozen pre-existing till sheets, at the transition from cold- to warm-based conditions under deglaciating ice sheets. In this paper, we present new data on the distribution of ribbed moraines and their close association with areas of frozen-bed conditions under ice sheets. In addition, we show examples of ribbed moraine ridges that fit together like a jig-saw puzzle. These observations indicate that fracturing and extension of a pre-existing till sheet may be a predominant process in ribbed moraine formation. In summary, we conclude that all described characteristics of ribbed moraines are compatible with the fracturing theory, while the shear and stack theory is hampered by an inability to explain many conspicuous features in the distribution pattern and detailed morphology of ribbed moraines. One implication of the fracturing theory is that the distribution of ribbed moraines can be used to reconstruct the extent of areas that underwent a change from frozen-bed to thawed-bed conditions under former ice sheets.

  2. Terrestrial planet formation

    PubMed Central

    Righter, K.; O’Brien, D. P.

    2011-01-01

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (∼106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally embryos to planets (107–108 y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  3. Primordial Planet Formation

    NASA Astrophysics Data System (ADS)

    Schild, Rudolph E.; Gibson, Carl H.

    Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the existence of molten nodules in STARDUST samples. And the theory of star formation does not explain the common occurrence of binary and multiple star systems in the standard gas fragmentation scenario. No current theory of planet formation can explain the iron core of the earth, under oceans of water. These difficulties are avoided in a scenario where the planet mass objects form primordially and are today the baryonic dark matter. They have been detected in quasar microlensing and anomalous quasar radio brightening bursts. The primordial planets often concentrate together to form a star, with residual matter seen in pre-stellar accretion discs around the youngest stars. These primordial planet mass bodies were formed of hydrogen-helium, aggregated in dense clumps of a trillion at the time of plasma neutralization 380,000 years after the big bang. Most have been frozen and invisible, but are now manifesting themselves in numerous ways as sensitive modern space telescopes become operational. Their key detection signature is their thermal emission spectrum, pegged at the 13.8 degrees Kelvin triple point of hydrogen, the baryonic dark matter (Staplefeldt et al. 1999).

  4. Liquid bridge formation

    NASA Astrophysics Data System (ADS)

    Sanz, A.; Perales, J. M.

    1989-10-01

    The formation of a liquid bridge is obviously the first step in the experimentation of the different aspects of the liquid bridge dynamics. Among the several candidate procedures of formation, the so-called 'cylindrical formation' has been selected; liquid is injected inside of the bridge through one of the supporting disks whereas simultaneously one of the disks is moved apart from the other at the proper speed to keep the volume of liquid inside the column, the same as that of the cylinder limited by both disks. Besides its own fluid mechanics interest (interplay between a jet and an interface), the results of this study would be very useful for experimenters in order to reduce the experiment preparation phase, as the total time allowed is scarce in most often used reduced gravity facilities (parabolic flights, sounding rockets and so on). A simplified theoretical model of the problem is presented which is valid in a flow regime limited in range by the Reynolds number of the injection jet. The existence of contiguous regimes and the influence of Ohnesorge number are suggested. This characterization has been deduced from the experiments performed by using the neutral buoyancy technique on earth and helps to explain the behavior observed during experiments performed on microgravity conditions onboard sounding rockets (TEXUS).

  5. CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

    SciTech Connect

    Duane A. Mcvay; Walter B. Ayers, Jr.; Jerry L. Jensen

    2004-02-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. The primary objectives for this reporting period were to construct a coal geological model for reservoir analysis and to continue modeling studies of CO{sub 2} sequestration performance in coalbed methane reservoirs under various operational conditions. Detailed correlation of coal zones is important for reservoir analysis and modeling. Therefore, we interpreted and created isopleth maps of coal occurrences, and correlated individual coal seams within the coal bearing subdivisions of the Wilcox Group--the Hooper, Simsboro and Calvert Bluff formations. Preliminary modeling studies were run to determine if gravity effects would affect the performance of CO{sub 2} sequestration in coalbed methane reservoirs. Results indicated that gravity could adversely affect sweep efficiency and, thus, volumes of CO{sub 2} sequestered and methane produced in thick, vertically continuous coals. Preliminary modeling studies were also run to determine the effect of injection gas composition on sequestration in low-rank coalbeds. Injected gas composition was varied from pure CO{sub 2} to pure N{sub 2}, and results show that increasing N{sub 2} content degrades CO{sub 2} sequestration and methane production performance. We have reached a Data Exchange Agreement with Anadarko Petroleum Corporation. We are currently incorporating the Anadarko data into our work, and expect these data to greatly enhance the accuracy and value of our studies.

  6. CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

    SciTech Connect

    Duane A. McVay; Walter B. Ayers Jr.; Jerry L. Jensen

    2005-05-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. The main objective for this reporting period was to perform pressure transient testing to determine permeability of deep Wilcox coal to use as additional, necessary data for modeling performance of CO{sub 2} sequestration and enhanced coalbed methane recovery. To perform permeability testing of the Wilcox coal, we worked with Anadarko Petroleum Corporation in selecting the well and intervals to test and in designing the pressure transient test. Anadarko agreed to allow us to perform permeability tests in coal beds in an existing shut-in well (Well APCT2). This well is located in the region of the Sam K. Seymour power station, a site that we earlier identified as a major point source of CO{sub 2} emissions. A service company, Pinnacle Technologies Inc. (Pinnacle) was contracted to conduct the tests in the field. Intervals tested were 2 coal beds with thicknesses of 3 and 7 feet, respectively, at approximately 4,100 ft depth in the Lower Calvert Bluff Formation of the Wilcox Group in east-central Texas. Analyses of pressure transient test data indicate that average values for coalbed methane reservoir permeability in the tested coals are between 1.9 and 4.2 mD. These values are in the lower end of the range of permeability used in the preliminary simulation modeling. These new coal fracture permeability data from the APCT2 well, along with the acquired gas compositional analyses and sorption capacities of CO{sub 2}, CH{sub 4}, and N{sub 2}, complete the reservoir description phase of the project. During this quarter we also continued work on reservoir and economic modeling to evaluate performance of CO{sub 2} sequestration and enhanced coalbed methane recovery.

  7. CO2 Sequestration Potential of Texas Low-Rank Coals

    SciTech Connect

    Duane A. McVay; Walter B. Ayers, Jr; Jerry L. Jensen

    2006-05-01

    The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (ECBM) recovery as an added benefit of sequestration. The main objectives for this reporting period were to (1) determine the effects of permeability anisotropy on performance of CO{sub 2} sequestration and ECBM production in the Lower Calvert Bluff Formation (LCB) of the Wilcox Group coals in east-central Texas, and (2) begin reservoir and economic analyses of CO{sub 2} sequestration and ECBM production using horizontal wells. To evaluate the effects of permeability anisotropy on CO{sub 2} sequestration and ECBM in LCB coal beds, we conducted deterministic reservoir modeling studies of 100% CO{sub 2} gas injection for the 6,200-ft depth base case (Case 1b) using the most likely values of the reservoir parameters. Simulation results show significant differences in the cumulative volumes of CH{sub 4} produced and CO{sub 2} injected due to permeability anisotropy, depending on the orientation of injection patterns relative to the orientation of permeability anisotropy. This indicates that knowledge of the magnitude and orientation of permeability anisotropy will be an important consideration in the design of CO{sub 2} sequestration and ECBM projects. We continued discussions with Anadarko Petroleum regarding plans for additional coal core acquisition and laboratory work to further characterize Wilcox low-rank coals. As part of the technology transfer for this project, we submitted the paper SPE 100584 for presentation at the 2006 SPE Gas Technology Symposium to be held in Calgary, Alberta, Canada on May 15-18, 2006.

  8. Model of kimberlite formation

    NASA Astrophysics Data System (ADS)

    Kostrovitsky, Sergey; Fiveyskaya, Lyudmila

    2013-04-01

    The critical goals in recognizing the nature of kimberlites are to find out: (1) the primary composition of melt of these rocks and (2) the principal processes of evolution of primary composition of kimberlites while ascending from mantle depth towards earth surface. Suppose, that the primary composition of kimberlite melt-fluid was in fact the composition of asthenosphere melt geochemically being close to alkaline-basalt (Hi-µ) saturated with high CO2. The genetic relation of kimberlites with basaltoids is indicated by a spatial and temporal affinity of their formation (Carlson et al, 2006; Lehmann et al, 2010; Tappe et al, 2012), similarity of the pattern of incompatible elements distribution, presence of megacryst minerals in alkaline basaltoids, Pyr-Alm garnet included, and finally, model calculation of parent melt composition for low-Cr megacryst minerals; it showed this composition to be typical for the alkaline basaltoid (Jones, 1980). At the asthenosphere level there was differentiation of basaltoid melt-fluid which was responsible for formation of its different parts with varying melt to fluid ratio and possibly varying content of alkalis (K2O). The outbreak of asthenosphere substance through lithosphere mantle proceeded by different scenarios: (a) With a noticeable dominance of fluid component kimberlites were formed by the capture and contamination of high-Mg, high-Cr rocks of lithosphere mantle that caused formation of high-Mg kimberlites. That corresponds to model of Russell (2012). (b) With a considerable proportion of melt phase depending on saturation in fluid there formed magnesium-ferriferous and ferriferous-titaniferous petrochemical types of kimberlites. There is no doubt that in formation of these kimberlite types the contamination of lithosphere material was the case, at the much lower level than in formation of high-Mg kimberlites. This model logically explains steady differences of petrochemistry of kimberlites making up clusters of different pipes, fields of pipes and even province. The model clarifies presence or absence of low-Cr, high-Ti megacryst association of minerals, with its crystallization proceeding in the melt phase of asthenosphere source of kimberlites. The role of hybridism in kimberlite emplacement is vivid in considering the features of composition of breccias and massive kimberlites composing pipe and dyke bodies of Kuoiksky field, in particular Obnazhennaya pipe. The former compared to massive varieties the kimberlites show much higher contents of SiO2, MgO and much lower CaO and CO2. Massive varieties of kimberlites are more ferriferous and titaniferous. The onset of breccias formation should evidently be attributed to the time of passing kimberlite melt-fluid through the lithosphere mantle. It is triggered by the processes of disintegration and capture of its rocks. Considering the composition of mantle xenoliths captured by the ascending flow of kimberlite mantle-fluid, the onset of the hybridization process should be referred to the boundary of asthenosphere and mantle lithosphere. The most deep-seated xenoliths are deformed lherzolites, which experienced the direct metasomatic effect of asthenosphere melt (Nixon, Boyd, 1973; Burgess & Harte, 2004). The hybrid nature of kimberlites assumes both the mechanic capture of fragmented material of lithosphere mantle and its inevitable partial assimilation causing a significant change of primary melt composition.

  9. Adiabatic Halo Formation

    SciTech Connect

    Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.

    2005-06-08

    In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.

  10. Star Formation in Irregular Galaxies.

    ERIC Educational Resources Information Center

    Hunter, Deidre; Wolff, Sidney

    1985-01-01

    Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)

  11. Changing Formats and Senior Reflections.

    ERIC Educational Resources Information Center

    Olman, Gloria

    1980-01-01

    Describes how one school switched its newspaper from the 8 1/2" x 11" mini-tab format to a larger, five-column format. Discusses some of the difficulties in changing and recounts some of the advantages. (TJ)

  12. Tooth formation - delayed or absent

    MedlinePLUS

    Delayed or absent tooth formation; Teeth - delayed or absent formation ... The age at which the tooth comes in varies. Most infants get their first tooth between 6 and 9 months, but it may be earlier or later. ...

  13. The Formative Evaluation Outcomes Matrix

    ERIC Educational Resources Information Center

    Wager, Walter

    1976-01-01

    Develops a heuristic device called the Formative Evaluation Outcomes Matrix that systematizes the data from three commonly used formative evaluation instruments for the purpose of diagnosing faults in products of the design process. (Author)

  14. Egg Formation in Lepidoptera

    PubMed Central

    Telfer, William H.

    2009-01-01

    Reproductive biology in the Twentieth Century produced comprehensive descriptions of the mechanisms of egg formation in most of the major orders of insects. While many general principles of ovarian development and physiology emerged, every order turned out to have a set of its own special motifs. Discovery of the lepidopteran motifs is summarized in this essay. The emphasis is on developmental mechanisms, beginning with the early growth and differentiation of female germ cells and ending, after many turns in morphogenesis, physiology and biosynthesis, with eggs that are filled with yolk and encased in chorions. Examples of uniquely lepidopteran traits include the cellular composition of ovarian follicles, the number of tubular ovarioles in which they mature, the functions of cell-to-cell junctional complexes in their maturation, their use of glycosaminoglycans to maintain intercellular patency during vitellogenesis, the role of proton and calcium pumps in their ion physiology, a separate postvitellogenic period of water and inorganic ion uptake, and the fine structure and protein composition of their chorions. Discovery of this combination of idiosyncracies was based on advances in the general concepts and techniques of cell and molecular biology and on insights borrowed from studies on other insects. The lepidopteran ovary in turn has contributed much to the understanding of egg formation in insects generally. PMID:20050770

  15. Urbanization and Slum Formation

    PubMed Central

    Phua, Kai Hong

    2007-01-01

    The formation of slums need not be inevitable with rapid urbanization. Such an argument appears to be contradicted by evidence of large slum populations in a large number of developing countries and particularly in rapidly urbanizing regions like Asia. The evidence discussed suggests that city authorities faced with rapid urban development lack the capacity to cope with the diverse demands for infrastructural provision to meet economic and social needs. Not only are strategic planning and intervention major issues in agenda to manage rapid urbanization, but city governments are not effectively linking the economic development trajectory to implications for urban growth and, hence, housing needs. In the following discussion, a case study is presented in support of the argument that city governments have to first recognize and then act to establish the link that is crucial between economic development, urban growth, and housing. This is the agendum that has been largely neglected by city and national governments that have been narrowly focused on economic growth with the consequent proliferation of slum formation as a housing solution. PMID:17387618

  16. Triggered Star Formation

    NASA Astrophysics Data System (ADS)

    Palous, J.; Ehlerov, S.

    2002-02-01

    The star formation triggered in dense walls of expanding shells is discussed. The fragmentation process is studied using the linear and non-linear perturbation theory. The influence of the energy input, the ISM distribution, and the speed of sound is examined analytically and by numerical simulations. We formulate the condition for the gravitational fragmentation of expanding shells: if the total surface density of the disc is higher than a certain critical value, shells are unstable. This value depends on the energy of the shell and the sound speed in the ISM. As an example the formation of OB associations near the Sun is discussed. We trace their orbits in the Milky Way to see where they have been born: 10-12 Myr ago progenitors of the Scorpius-Centaurus OB associations and the Orion OB association resided together within a sheet-like region elongated in the l = 20^o-200^o direction, showing that the local OB associations may be formed as fragments of an expanding supershell.

  17. Planet Formation - Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2005-01-01

    Modern theories of star and planet formation are based upon observations of planets and smaller bodies within our own Solar System, exoplanets &round normal stars and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path.

  18. Deep Water Formation

    NASA Technical Reports Server (NTRS)

    Killworth, P. D.

    1984-01-01

    Some simple arguments on plumes of dense water and filling boxes were given. What determines the time for a large-scale environment to be modified by the injection of dense water at its edge is the mass flux, not the buoyancy flux. However, it is the denser buoyancy flux, when there are several competing plumes (e.g., the Mediterranean outflow versus the Denmark Strait outflow) that determines which plume will provide the bottom water for that ocean basin. It was noted that the obvious laboratory experiment (rotate a pie-shaped annulus, and heat/cool it on the surface) had never been performed. Thus, to some extent our belief that deep convection is somehow automatic at high latitudes to close off some ill-defined meridional circulation has never been tested. A summary of deep convection was given. The two fundamental formation mechanisms were shown. Of the two, it is open-ocean convection which forms the water which supplies the Denmark Strait overflow -- in all likelihood, as formation in the Greenland Sea remains stubbornly unobserved. But it is the slope convection which finally creates North Atlantic deep water, following the Denmark Strait overspill.

  19. The Planet Formation Imager

    NASA Astrophysics Data System (ADS)

    Kraus, S.; Buscher, D. F.; Monnier, J. D.; PFI Science, the; Technical Working Group

    2014-04-01

    Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work is being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planet-hosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI and discuss how PFI could significantly advance our understanding of the architecture and potential habitability of planetary systems. We present radiation-hydrodynamics simulations from which we derive preliminary specifications that guide the design of the facility. Finally, we give an overview about the interferometric and non-interferometric technologies that we are investigating in order to meet the specifications.

  20. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1994-01-01

    Two KC-135 flight campaigns have been conducted to date which are specifically dedicated to study bubble formation in microgravity. The first flight was conducted during March 14-18, 1994, and the other during June 20-24, 1994. The results from the June 1994 flight have not been analyzed yet, while the results from the March flight have been partially analyzed. In the first flight three different experiments were performed, one with the specific aim at determining whether or not cavitation can take place during any of the fluid handling procedures adopted in the shuttle bioprocessing experiments. The other experiments were concerned with duplicating some of the procedures that resulted in bubble formation, namely the NCS filling procedure and the needle scratch of a solid surface. The results from this set of experiments suggest that cavitation did not take place during any of the fluid handling procedures. The results clearly indicate that almost all were generated as a result of the breakup of the gas/liquid interface. This was convincingly demonstrated in the scratch tests as well as in the liquid fill tests.

  1. Satellite formation flying

    NASA Astrophysics Data System (ADS)

    Yan, Qiguo

    2002-09-01

    The control of Distributed Satellite Formation Flying (DSFF) has attracted the attention of many researchers over the past decade. The increasing stringent performance specifications required for controlling DSFF systems necessitates the accurate maintenance of the relative positions/orientations of the participating satellites. This research focuses on the development of new effective controllers for DSFF system via various linear and nonlinear approaches. Based on the classical Hill's equation, a mathematically rigorous control design framework is proposed for linear control of DSFF with guaranteed closed-loop stability. In particular, a pulse-based, periodic gain, control architectures is developed which utilize intermittent control action. Next, a Lyapunov-based, nonlinear adaptive control law is designed which guarantees global asymptotic convergence of position tracking error. In addition, a nonlinear, output feedback control law for DSFF is presented, which guarantees global uniformly ultimately bounded position and velocity tracking error in the presence of some DSFF system parametric uncertainties. Another contribution of this research consists of the development of the perturbative control of satellite flying around the oblate earth which can pave the way for its direct application of one class of optimal formation flying in polar orbits. Numerical simulations are presented to demonstrate the efficacies of the proposed control design methodologies.

  2. Method for measuring pollutant formation

    NASA Technical Reports Server (NTRS)

    Annen, Kurt (Inventor); Stickler, David B. (Inventor)

    2001-01-01

    Diagnostic methods for determining an instantaneous rate of pollutant formation in a combustion system are based on measurement of chemiluminescence intensity generated simultaneously with the formation of the pollutant. The chemiluminescent signal is generated by an analog reaction which occurs in parallel with a key step in the formation of a specific pollutant of interest. The connection between the analog reaction and the pollution reaction is such that the chemiluminescent signal indicates the local, instantaneous formation rate of the pollutant of interest.

  3. Formative Assessment: Simply, No Additives

    ERIC Educational Resources Information Center

    Roskos, Kathleen; Neuman, Susan B.

    2012-01-01

    Among the types of assessment the closest to daily reading instruction is formative assessment. In contrast to summative assessment, which occurs after instruction, formative assessment involves forming judgments frequently in the flow of instruction. Key features of formative assessment include identifying gaps between where students are and

  4. Group Formation in Economics

    NASA Astrophysics Data System (ADS)

    Demange, Gabrielle; Wooders, Myrna

    2005-01-01

    Broad and diverse ranges of activities are conducted within and by organized groups of individuals, including political, economic and social activities. These activities have recently become a subject of intense interest in economics and game theory. Some of the topics investigated in this collection are models of networks of power and privilege, trade networks, co-authorship networks, buyer-seller networks with differentiated products, and networks of medical innovation and the adaptation of new information. Other topics are social norms on punctuality, clubs and the provision of club goods and public goods, research and development and collusive alliances among corporations, and international alliances and trading agreements. While relatively recent, the literature on game theoretic studies of group formation in economics is already vast. This volume provides an introduction to this important literature on game-theoretic treatments of situations with networks, clubs, and coalitions, including some applications.

  5. The Argument Interchange Format

    NASA Astrophysics Data System (ADS)

    Rahwan, Iyad; Reed, Chris

    While significant progress has been made in understanding the theoretical properties of different argumentation logics and in specifying argumentation dialogues, there remain major barriers to the development and practical deployment of argumentation systems. One of these barriers is the lack of a shared, agreed notation or interchange format for argumentation and arguments. In the last years a number of different argument mark-up languages have been proposed in the context of tools developed for argument visualisation and construction (see [10] for a review). Thus, for example, the Assurance and Safety Case Environment (ASCE)1 is a graphical and narrative authoring tool for developing and managing assurance cases, safety cases and other complex project documentation.

  6. Transitions in biofilm formation

    NASA Astrophysics Data System (ADS)

    Gordon, Vernita; Thatcher, Travis; Cooley, Benjamin

    2011-03-01

    Biofilms are multicellular, dynamic communities formed by interacting unicellular organisms bound to a surface. Forming a biofilm is a developmental process, characterized by sequential changes in gene expression and behavior as bacteria and yeast progress from discrete, free-swimming cells though stages that arrive at a mature biofilm. We are developing automated metrics to identify key transitions in early biofilm formation as cells attach to a surface, populate that surface, and adhere to each other to form early microcolonies. Our metrics use high-throughput tracking and analysis of microscopy movies to localize these transitions in space and time. Each of these transitions is associated with a loss of entropy in the bacterial system and, therefore, with biological activity that drives this loss of entropy. Better understanding of these transitions will allow automated determination of the strength and turn-on of attractive cell-surface and cell-cell interactions as biofilm development progresses.

  7. Frost formation with salt

    NASA Astrophysics Data System (ADS)

    Guadarrama-Cetina, J.; Mongruel, A.; González-Viñas, W.; Beysens, D.

    2015-06-01

    The formation of frost in presence of salt (NaCl) crystal is experimentally investigated on a hydrophobic surface. It presents several remarkable features due to the interplay of salty-water saturation pressure evolution, initially lower than the saturation pressure of ice and water, and the percolating propagation of ice dendrites from defects throughout the supercooled water droplet pattern. In particular, it is remarkable that nucleation of supercooled water and/or ice is prevented around the salty drop in a region of inhibited condensation where the substrate remains dry. As condensation proceeds, salt concentration decreases to eventually become lower than ice's, allowing ice dendrites to hit the salty drop. Salty water then melts ice but eventually freezes as an effect of dilution.

  8. DUST FORMATION IN MACRONOVAE

    SciTech Connect

    Takami, Hajime; Ioka, Kunihito; Nozawa, Takaya E-mail: kunihito.ioka@kek.jp

    2014-07-01

    We examine dust formation in macronovae (as known as kilonovae), which are the bright ejecta of neutron star binary mergers and one of the leading sites of r-process nucleosynthesis. In light of information about the first macronova candidate associated with GRB 130603B, we find that dust grains of r-process elements have difficulty forming because of the low number density of the r-process atoms, while carbon or elements lighter than iron can condense into dust if they are abundant. Dust grains absorb emission from ejecta with an opacity even greater than that of the r-process elements, and re-emit photons at infrared wavelengths. Such dust emission can potentially account for macronovae without r-process nucleosynthesis as an alternative model. This dust scenario predicts a spectrum with fewer features than the r-process model and day-scale optical-to-ultraviolet emission.

  9. Galaxy formation by dust

    NASA Technical Reports Server (NTRS)

    Wang, Boqi; Field, Goerge B.

    1989-01-01

    It has been known since the early 1940's that radiation can cause an instability in the interstellar medium. Absorbing dust particles in an isotropic radiation field shadow each other by a solid angle which is inversely proportional to the square of the distance between the two particles, leading to an inverse-square attractive force - mock gravity. The effect is largest in an optically thin medium. Recently Hogan and White (HW, hereafter) proposed that if the pre-galactic universe contained suitable sources of radiation and dust, instability in the dust distribution caused by mock gravity may have led to the formation of galaxies and galaxy clusters. In their picture of a well-coupled dust-gas medium, HW show that mock gravity begins to dominate gravitational instability when the perturbation becomes optically thin, provided that the radiation field at the time is strong enough. The recent rocket observation of the microwave background at submillimeter wavelengths by Matsumoto et al. might be from pre-galactic stars, the consequence of the absorption of ultraviolet radiation by dust, and infrared reemission which is subsequently redshifted. HW's analysis omits radiative drag, incomplete collisional coupling of gas and dust, finite dust albedo, and finite matter pressure. These effects could be important. In a preliminary calculation including them, the authors have confirmed that mock gravitational instability is effective if there is a strong ultraviolet radiation at the time, but any galaxies that form would be substantially enriched in heavy elements because the contraction of the dust is more rapid than that of the gas. Moreover, since the dust moves with supersonic velocity through the gas soon after the perturbation becomes optically thin, the sputtering of dust particles by gas is significant, so the dust could disappear before the instability develops significantly. They conclude that the mock gravity by dust is not important in galaxy formations.

  10. Hazards to Planet Formation

    NASA Astrophysics Data System (ADS)

    Bally, J.

    2001-05-01

    The Orion Nebula provides a remarkable window on the first few million years in the lives of typical young stars and planetary systems. HST has demonstrated that most young stars in the Nebula are surrounded by circumstellar disks (the so-called `proplyds'). While these observations show that planet forming environments may be common, they also demonstrate that Orion's disks are being destroyed by intense UV radiation fields. `Gravel' sufficiently large to resist photo-erosion (meter scale solids or ices) may lock-up sufficient material to eventually build rocky planets. Indeed, there is evidence for large solids in some proplyds. But, the hydrogen and helium needed for the formation of giant planets will be removed. To form in Orion-like environments, giant planets must be assembled promptly prior to UV exposure. Even rocky planets may not form if the photoionized disk corona causes surviving large particles in the disk to spiral into the central star. Thus, nearby massive stars pose severe hazards to planet formation. Star counts indicate that most stars form in Orion-like environments. Only about 10% of young stars are born in shielded environments such as the Taurus or L1641 clouds where disks may escape photo-erosion. In dark clouds, the majority of stars (> 80%) form in non-hierarchal multiple star systems where close encounters with sibling stars can destroy disks and eject young planets. Thus, most stars may never develop planetary systems. These considerations indicate that extra-Solar planets may be rare, contrary to the popular view. These conclusions are consistent with the recent discoveries of extra-Solar planets around a few percent of single stars.

  11. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 16 April 2002) The Science This THEMIS visible image was acquired near 11o N, 159o W (201o E) and shows examples of the remarkable variations that can be seen in the erosion of the Medusae Fossae Formation. This Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region, like many others throughout the Medusae Fossae Formation, the surface has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to erode the landscape of Mars. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Within this single image it is possible to see differing amounts of erosion and stripping of layers in the Medusae Fossae Formation. Near the bottom (southern) edge of the image a rock layer with a relatively smooth upper surface covers much of the image. Moving upwards (north) in the image this layer becomes more and more eroded. At first there are isolated regions where the smooth unit has been eroded to produce sets of parallel ridges and knobs. Further north these linear knobs increase in number, and only small, isolated patches of the smooth upper surface remain. Finally, at the top of the image, even the ridges have been removed, exposing the remarkably smooth top of hard, resistant layer below. This sequence of layers with differing hardness and resistance to erosion is common on Earth and on Mars, and suggests significant variations in the physical properties, composition, particle size, and/or cementation of these martian layers. As is common throughout the Medusae Fossae Formation, very few impact craters are visible, indicating that the surface exposed is relatively young, and that the process of erosion may be active today. The Story 'Yardang!' Now, that may seem like a peculiar-sounding curse word, but nobody would get in trouble for using it. A yardang is one of the very cool-sounding words geologists use to describe long, irregular features like the ones seen in this image. Yardangs are grooved, furrowed ridges that form as the wind erodes away weakly cemented material in the region. Rippling across the surface, yardangs tell the story of how the powerful Martian wind carved the surface into such a gorgeous pattern over time. (Don't miss clicking on the above image to see a detailed view, in which the beauty and almost dance-like symmetry of the waving terrain pops out in highly compelling, three-dimensional texture.) It may be easy to see which way the wind blows in this area, since these streamlined features point in the direction of prevailing winds. But how can geologists understand the various kinds of terrain seen here? First, they have to study the different patterns of erosion, looking closely at how the wind has stripped off certain layers and not others. Want to be a geologist yourself? Start at the bottom of the image and scroll upward, and see how the relatively smooth, higher terrain toward the south gradually becomes more and more eroded. Moving up the image, at first you?ll see only a few, isolated regions of parallel ridges and knolls. Go a little farther north with your eyes (toward the center of the image), and you?ll see how these linear knobs really get going! Once you get to the top of the image, only patches of these grooved ridges remain, leaving an incredibly smooth, wind-scrubbed surface behind. You know this layer has to be made of pretty hard material, because it seems impervious to further erosion. Geologists studying Mars can compare these Martian yardangs to examples found on Earth, such as those in the Lut desert of Iran. Humans have even been known to use the wind as their inspiration, sculpting the shape of yardangs themselves. The famous sphynx at Giza in Egypt is thought to be a yardang that's been whittled

  12. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 16 April 2002) The Science This THEMIS visible image was acquired near 11o N, 159o W (201o E) and shows examples of the remarkable variations that can be seen in the erosion of the Medusae Fossae Formation. This Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region, like many others throughout the Medusae Fossae Formation, the surface has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to erode the landscape of Mars. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Within this single image it is possible to see differing amounts of erosion and stripping of layers in the Medusae Fossae Formation. Near the bottom (southern) edge of the image a rock layer with a relatively smooth upper surface covers much of the image. Moving upwards (north) in the image this layer becomes more and more eroded. At first there are isolated regions where the smooth unit has been eroded to produce sets of parallel ridges and knobs. Further north these linear knobs increase in number, and only small, isolated patches of the smooth upper surface remain. Finally, at the top of the image, even the ridges have been removed, exposing the remarkably smooth top of hard, resistant layer below. This sequence of layers with differing hardness and resistance to erosion is common on Earth and on Mars, and suggests significant variations in the physical properties, composition, particle size, and/or cementation of these martian layers. As is common throughout the Medusae Fossae Formation, very few impact craters are visible, indicating that the surface exposed is relatively young, and that the process of erosion may be active today. The Story 'Yardang!' Now, that may seem like a peculiar-sounding curse word, but nobody would get in trouble for using it. A yardang is one of the very cool-sounding words geologists use to describe long, irregular features like the ones seen in this image. Yardangs are grooved, furrowed ridges that form as the wind erodes away weakly cemented material in the region. Rippling across the surface, yardangs tell the story of how the powerful Martian wind carved the surface into such a gorgeous pattern over time. (Don't miss clicking on the above image to see a detailed view, in which the beauty and almost dance-like symmetry of the waving terrain pops out in highly compelling, three-dimensional texture.) It may be easy to see which way the wind blows in this area, since these streamlined features point in the direction of prevailing winds. But how can geologists understand the various kinds of terrain seen here? First, they have to study the different patterns of erosion, looking closely at how the wind has stripped off certain layers and not others. Want to be a geologist yourself? Start at the bottom of the image and scroll upward, and see how the relatively smooth, higher terrain toward the south gradually becomes more and more eroded. Moving up the image, at first you?ll see only a few, isolated regions of parallel ridges and knolls. Go a little farther north with your eyes (toward the center of the image), and you?ll see how these linear knobs really get going! Once you get to the top of the image, only patches of these grooved ridges remain, leaving an incredibly smooth, wind-scrubbed surface behind. You know this layer has to be made of pretty hard material, because it seems impervious to further erosion. Geologists studying Mars can compare these Martian yardangs to examples found on Earth, such as those in the Lut desert of Iran. Humans have even been known to use the wind as their inspiration, sculpting the shape of yardangs themselves. The famous sphynx at Giza in Egypt is thought to be a yardang that's been whittled down a little more by ancient human chiselers.

  13. 75 FR 31835 - Environmental Impact Statement: Calvert and St. Mary's Counties, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-04

    ... Counties, Maryland (Federal Register Vol. 72, No. 203; FR Doc. 07-5190) is being withdrawn and an..., pedestrian and bicycle safety along MD 4, while supporting existing and planned development in the...

  14. 76 FR 22935 - Calvert Cliffs Nuclear Power Plant, LLC Independent Spent Fuel Storage Installation; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-25

    ... renewed for 40 years. On February 16, 2011, (76 FR 8872) the revised 10 CFR 72.230(b) rule was published... be filed in accordance with the NRC E-Filing rule (72 FR 49139, August 28, 2007). The E-Filing... install a Web browser plug-in from the NRC Web site. Further information on the Web- based submission...

  15. Uranyl formate monohydrate spectroscopy

    SciTech Connect

    Porter, J.T. II; Muller, C.H. III; West, W.P.; Malley, M.M.

    1983-10-01

    We report the fluorescence excitation and emission spectra of normal and isotopically labeled uranyl formate monohydrate powder, UO/sub 2/(HCOO)/sub 2/.H/sub 2/O, at 4.2/sup 0/K. Dual fluorescence from the two lowest excited states, I and II, occurs in this compound giving rise to a temperature-dependent lifetime. The lowest vibronic levels are assigned on the basis of the observed oxygen and uranium isotope shifts. The unusual activity and relative frequencies of the symmetric and asymmetric O-U-O stretches in the excited state and can be successfully predicted with the addition of a bond-bond interaction term in addition to the usual valence bond potential. The kinetics of nonresonant energy transfer between isotopic /sup x/OU/sup y/O/sup +2/ antitraps and the U/sup 16/O/sub 2//sup +2/ lattice were measured over the range from 1.7 to 4.2/sup 0/K. The observed rates are in agreement with a quadrupole-quadrupole coupling mechanism accompanied by one and two phonon processes which compensate for the energy defect. The asymmetric lineshapes, broader linewidths and tenfold reduction of absorption intensity for the U/sup 16/O/sub 2//sup +2/ lattice compared to the isolated isotopically doped uranyl ions are attributed to the collective nature of the excited state for the majority species.

  16. Bead lightning formation

    NASA Astrophysics Data System (ADS)

    Ludwig, G. O.; Saba, M. M. F.

    2005-09-01

    Formation of beaded structures in triggered lightning discharges is considered in the framework of both magnetohydrodynamic (MHD) and hydrodynamic instabilities. It is shown that the space periodicity of the structures can be explained in terms of the kink and sausage type instabilities in a cylindrical discharge with anomalous viscosity. In particular, the fast growth rate of the hydrodynamic Rayleigh-Taylor instability, which is driven by the backflow of air into the channel of the decaying return stroke, dominates the initial evolution of perturbations during the decay of the return current. This instability is responsible for a significant enhancement of the anomalous viscosity above the classical level. Eventually, the damping introduced at the current channel edge by the high level of anomalous viscous stresses defines the final length scale of bead lightning. Later, during the continuing current stage of the lightning flash, the MHD pinch instability persists, although with a much smaller growth rate that can be enhanced in a M-component event. The combined effect of these instabilities may explain various aspects of bead lightning.

  17. Nuclear ``pasta'' formation

    NASA Astrophysics Data System (ADS)

    Schneider, A. S.; Horowitz, C. J.; Hughto, J.; Berry, D. K.

    2013-12-01

    The formation of complex nonuniform phases of nuclear matter, known as nuclear pasta, is studied with molecular dynamics (MD) simulations containing 51200 nucleons. A phenomenological nuclear interaction is used that reproduces the saturation binding energy and density of nuclear matter. Systems are prepared at an initial density of 0.10fm-3 and then the density is decreased by expanding the simulation volume at different rates to densities of 0.01fm-3 or less. An originally uniform system of nuclear matter is observed to form spherical bubbles (“swiss cheese”), hollow tubes, flat plates (“lasagna”), thin rods (“spaghetti”) and, finally, nearly spherical nuclei with decreasing density. We explicitly observe nucleation mechanisms, with decreasing density, for these different pasta phase transitions. Topological quantities known as Minkowski functionals are obtained to characterize the pasta shapes. Different pasta shapes are observed depending on the expansion rate. This indicates nonequilibrium effects. We use this to determine the best ways to obtain lower energy states of the pasta system from MD simulations and to place constraints on the equilibration time of the system.

  18. Formation of nuclear heterochromatin

    PubMed Central

    Guetg, Claudio; Santoro, Raffaella

    2012-01-01

    Establishment and inheritance of heterochromatic states is critical in maintaining genome integrity and gene expression state. The elucidation of the mechanisms implicated in these processes is fundamental to understand the control of epigenetic regulation of the genome. Recently, the nucleolus emerged as an important component of the nuclear architecture. Although the nucleolus is the most active site of cellular transcription, it is also an attractive compartment for nuclear heterochromatic regions, such as pericentric repeats, inactive X chromosome and regions with low gene density significantly enriched in repressed genes. The coexistence of euchromatic and heterochromatic rRNA genes in each cell reflects these two opposite functions of the nucleolus. An epigenetic network that is controlled by NoRC complex establishes and maintains rDNA heterochromatin. It is here discussed how heterochromatic rRNA genes and the associated epigenetic regulatory activities might mediate formation and inheritance of nuclear heterochromatic regions. Finally, we propose that the analysis of the components of heterochromatic rRNA genes will be not only relevant to understand the general composition of heterochromatin but has the potential to provide important and novel insights of how nuclear heterochromatic structures are established and inherited. PMID:22735386

  19. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1996-01-01

    An extensive experimental program was initiated for the purpose of understanding the mechanisms leading to bubble generation during fluid handling procedures in a microgravity environment. Several key fluid handling procedures typical for PCG experiments were identified for analysis in that program. Experiments were designed to specifically understand how such procedures can lead to bubble formation. The experiments were then conducted aboard the NASA KC-135 aircraft which is capable of simulating a low gravity environment by executing a parabolic flight attitude. However, such a flight attitude can only provide a low gravity environment of approximately 10-2go for a maximum period of 30 seconds. Thus all of the tests conducted for these experiments were designed to last no longer than 20 seconds. Several experiments were designed to simulate some of the more relevant fluid handling procedures during protein crystal growth experiments. These include submerged liquid jet cavitation, filling of a cubical vessel, submerged surface scratch, attached drop growth, liquid jet impingement, and geysering experiments. To date, four separate KC-135 flight campaigns were undertaken specifically for performing these experiments. However, different experiments were performed on different flights.

  20. Acromioclavicular joint cyst formation.

    PubMed

    Hiller, Andrew D; Miller, Joshua D; Zeller, John L

    2010-03-01

    Acromioclavicular joint (ACJ) cysts are an uncommon and unusual sequela associated with shoulder pathophysiology. The majority of literature on ACJ cysts consists of individual case reports with no definitive literature review currently available. In addition to a comprehensive literature review, four clinical cases are presented in this report. First described by Craig (1984), a total of 41 cases have been previously reported in the literature. Of these cases, five occurred with the rotator cuff musculature intact. The remaining 36 cases of ACJ cysts occurred in patients with a complete tear/avulsion of the rotator cuff. Previous attempts at compiling a complete record of all reported cases have combined several distinct conditions into a single category. This article presents two distinct etiologies for the pathogenesis of ACJ cyst formation. In the presence of an intact rotator cuff, a Type 1 cyst can form superficially and be limited to the ACJ. Following a massive or traumatic tear of the rotator cuff, mechanical instability of the humeral head can cause a deterioration of the inferior acromioclavicular capsule (cuff tear arthropathy) and an overproduction of synovial fluid. Overtime, a "geyser" of fluid can form between the glenohumeral and the ACJ, forming a Type 2 cyst. This differentiation and categorization is essential for appropriate classification and treatment. PMID:20069645

  1. Bead lightning formation

    SciTech Connect

    Ludwig, G.O.; Saba, M.M.F.

    2005-09-15

    Formation of beaded structures in triggered lightning discharges is considered in the framework of both magnetohydrodynamic (MHD) and hydrodynamic instabilities. It is shown that the space periodicity of the structures can be explained in terms of the kink and sausage type instabilities in a cylindrical discharge with anomalous viscosity. In particular, the fast growth rate of the hydrodynamic Rayleigh-Taylor instability, which is driven by the backflow of air into the channel of the decaying return stroke, dominates the initial evolution of perturbations during the decay of the return current. This instability is responsible for a significant enhancement of the anomalous viscosity above the classical level. Eventually, the damping introduced at the current channel edge by the high level of anomalous viscous stresses defines the final length scale of bead lightning. Later, during the continuing current stage of the lightning flash, the MHD pinch instability persists, although with a much smaller growth rate that can be enhanced in a M-component event. The combined effect of these instabilities may explain various aspects of bead lightning.

  2. The KEA image file format

    NASA Astrophysics Data System (ADS)

    Bunting, Peter; Gillingham, Sam

    2013-08-01

    There are a large number of image formats already in use within the remote sensing community but currently there is no format that provides the features of: compression, support for large file sizes, ground control points, raster attribute tables and inbuilt image pyramids. Therefore, a new image format, named KEA, after the New Zealand bird, has been proposed. The KEA format provides a full implementation of the GDAL data model and is implemented within a HDF5 file. A software library with a GDAL driver have been freely provided to the community allowing use through any GDAL based software. The new format has comparable performance with existing formats while producing smaller file sizes and is already within active use for a number of projects within Landcare Research, New Zealand, and the wider community.

  3. Triglycerides and gallstone formation.

    PubMed

    Smelt, A H M

    2010-11-11

    Changes in bile acid (BA) metabolism and gallbladder function are critical factors in the pathogenesis of gallstones. Patients with hypertriglyceridemia (HTG) - often overweight and insulin resistant - are at risk for gallstone disease. The question arises whether HTG itself contributes to gallstone formation or whether gallstone disease only associates with this disorder. Triglycerides are formed in response to fluxes of non-esterified fatty acids and glucose. Hypertriglyceridemia results from either overproduction of triglycerides by the liver, impaired lipolysis or a combination of both. Hyperinsulinemia, as observed in the insulin resistant state, stimulates very low-density lipoprotein (VLDL)-triglyceride synthesis. Peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptor (FXR) and hepatocyte nuclear factor 4? (HNF4?) are the nuclear receptors involved in the regulation of lipogenesis. Microsomal triglyceride transfer protein (MTP) is involved in the production of VLDL and its activation is also under control of transcription factors as FXR and Forkhead box-O1 (FoxO1). Triglyceride and BA metabolism are linked. There is an inverse relationship between bile acid fluxes and pool size and VLDL production and SHP (small heterodimer partner) and FXR are the link between BAs and TG metabolism. BAs are also ligands for FXR and G-protein-coupled receptors, such as TGR5. FXR activation by BAs suppresses the expression of MTP, transcription factor sterol regulatory element binding protein (SREBP)-1c and other lipogenic genes. LXRs stimulate lipogenesis whereas FXRs inhibit the metabolic process. Synthesis of BAs from cholesterol occurs either via the classical pathway (7?-hydroxylation of cholesterol; CYP7A1) or via the alternate pathway (CYP39A1 or CYP7B1). BAs induce FXR, which inhibits CYP7A1 transcription by activation of SHP and inhibition of HNF4? transactivation. Bile composition (supersaturation with cholesterol), gallbladder dysmotility, inflammation, hypersecretion of mucin gel in the gallbladder and slow large intestinal motility and increased intestinal cholesterol absorption may contribute to the pathogenesis of cholesterol gallstones. In HTG patients supersaturated bile may be related to the presence of obesity rather than to HTG itself. Contraction and relaxation of the gallbladder are regulated by neuronal, hormonal and paracrine factors. Postprandial gallbladder emptying is regulated by cholecystokinin (CCK). Poor postprandial gallbladder contraction may be due to the magnitude of the CCK response and to the amount of CCK receptors in the gallbladder smooth muscle cells. In the fasting state gallbladder motility is associated with the intestinal migrating motor complex (MMC) activity and with elevated plasma motilin levels. Fibroblast growth factor (FGF19), produced on arrival of bile acids in the ileum, is also important for gallbladder motility. Gallbladder motility is impaired in HTG patients compared to BMI matched controls. There is evidence that the gallbladder in HTG is less sensitive to CCK and that this sensitivity improves after reversal of high serum TG levels by use of TG lowering agents. In hypertriglyceridemia TG lowering therapy (fibrates or fish-oil) is essential to prevent cardiovascular disease and pancreatitis. Fibrates, however, also increase the risk for cholelithiasis by increasing biliary cholesterol saturation and by reduction of bile acid synthesis. On the other hand fish-oil decreases biliary cholesterol saturation. Fish-oil may increase bile acid synthesis by activation of 7alpha-hydroxylase and may inhibit VLDL production and secretion through activation of nuclear factors and increased apoB degradation. In HTG patients, gallbladder motility improves during bezafibrate as well as during fish-oil therapy. The question remains whether improvement of gallbladder motility and increased lithogenicity of bile by bezafibrate therapy counteract each other or still result in gallstone formation in HTG patients. PMID:20699090

  4. Microdiamonds Formation During

    NASA Astrophysics Data System (ADS)

    Ogasawara, Y.

    2005-12-01

    The previous studies on the Kokchetav UHPM rocks by the authors group demonstrated the following subjects on the formation of microdiamonds. Microdiamond is highly abundant (max. ca. 2700carat/ton) in dolomite marble that has diopside (with K-bearing silicate lamella)-dolomite-garnet assemblage and was stable at XCO2=0.1. The microdiamonds in dolomite marble are classified into 3- types; S, R and T. The dominant type S (ca. 80%) indicates that it grew at two stages, the core and rim stages. R-type grew mainly at the core stage, and T-type grew at the rim stage (Ishida et al., 2003; Yoshioka & Ogasawara, 2005). One of the possible source of carbon for the 2nd stage growth is a fluid during UHPM. Some domains of dolomite marble contacting with dolomitic marble lack diamond, and indicate are lower XCO2 than diamond-bearing marble. No diamond occurs in dolomitic marble that is a product of strong H2O-rich fluid effect during UHPM (Ogasawara & Aoki, 2005); Ti-clinohumite-aragonite corresponds to extremely low-XCO2 (=<0.01), and the TiO2 carrier could be a H2O-rich fluid. Hydroxyl in lamellar-free diopside was confirmed as > 850ppm (Kikuchi & Ogasawara, in press). Low XCO2 condition corresponds to relatively oxidized conditions (Ogasawara et al., 2000). Extremely low-XCO2 conditions are unsuitable for diamond formation. A small amount of microdiamond (61 grains) occurs in diopside (with lamellar) in some layers of titanite-bearing calcite marble. Other domain contains titanite with coesite exsolution and the precursor silica-excess composition of titanite gave the minimum pressure as 6 GPa (Ogasawara et al., 2002). The presence of titanite (including relic aragonite + rutile) indicates very low-XCO2 (ca. 0.02). All grains of microdiamond are similar to R-type in morphology. No evidence for the 2nd stage diamond growth was observed. No diamond occurs in garnet- clinopyroxene rock like _gskarns_h. This rock has UHP evidence; coesite exsolution in titanite and K- bearing-silicate lamella in clinopyroxene, and is a product of the metasomatism (indicating very low XCO2) under UHP. The lack of diamond is consistent with other diamond-free carbonate rocks that were stable under extremely low- XCO2. The 2nd abundant diamond-bearing rock is pelitic gneiss. The characteristic features of microdiamonds show the strong contrast with those in dolomite marble. The dominant morphology is rounded to cuboidal form with rugged surface (> 80%); this corresponds to R- type. S-type is rare in pelitic gneiss. Morphology of microdiamond is controlled by growth and/or dissolution. Rounded grain with smooth surface may show the resorption after diamond growth. The absence of S-type diamond is a great difference from the microdiamond in dolomite marble, and indicates that fluid played different roles in both two diamond-bearing rocks; 1) carbon dissolved into aqueous fluid in pelitic gneiss, and 2) carbon precipitated from fluid to form microdiamond at the 2nd stage in dolomite marble. The microdiamond formed at the 2nd stage might be closely related to UHPM fluid. A model for fluid evolution from CO2-rich to H2O-rich during prograde stage can explain the metamorphic history of the Kokchetav carbonate rocks. Such UHPM fluid evolution may be caused by the dehydration in gneisses/eclogites surrounding the carbonate. Summarizing these, ``Intraslab UHP metasomatism" could be proposed. References: Ishida et al. (2003) J. Metamorphic Geol., 21. Kikuchi & Ogasawara (in press) GSA Special Papers. Ogasawara et al. (2000) Island Arc, 9, 400-416. Ogasawara et al. (2002) Am. Min., 87, 454-461. Ogasawara & Aoki (2005) Int. Geol. Rev., 47 (in press). Yoshioka & Ogasawara (2005) Int. Geol. Rev., 47, 703-715.

  5. Lysosomal ROS formation.

    PubMed

    Nohl, Hans; Gille, Lars

    2005-01-01

    Ubiquinone is inhomogenously distributed in subcellular biomembranes. Apart from mitochondria, where ubiquinone has bioenergetic and pathophysiological functions, unusually high levels of ubiquinone have also been reported in Golgi vesicles and lysosomes. In lysosomes, the interior differs from other organelles in its low pH value which is important to ensure optimal activity of hydrolytic enzymes. Since redox-cycling of ubiquinone is associated with the acceptance and release of protons, we assumed that ubiquinone is part of a redox chain contributing to unilateral proton distribution. A similar function of ubiquinone was earlier suggested by Crane to operate in Golgi vesicles. Support for the involvement of ubiquinone in a presumed couple of redox carriers came from our observation that almost 70% of total lysosomal ubiquinone was in the divalently reduced state. Further reduction was seen in the presence of external NADH. Analysis of the components involved in the transfer of reducing equivalents from cytosolic NADH to ubiquinone revealed the existence of an FAD-containing NADH dehydrogenase. The latter was found to reduce ubiquinone by means of a b-type cytochrome. Proton translocation into the interior was linked to the activity of the novel lysosomal redox chain. Oxygen was found to be the terminal electron acceptor, thereby also regulating acidification of the lysosomal matrix. In contrast to mitochondrial respiration, oxygen was only trivalently reduced giving rise to the release of HO radicals. The role of this novel proton-pumping redox chain and the significance of the associated ROS formation has to be elucidated. PMID:16259787

  6. Planet formation and searches

    NASA Astrophysics Data System (ADS)

    Montgomery, Ryan Michael

    2009-08-01

    This thesis explores the possibilities for discovery of terrestrial-mass planets in the habitable zones of their host stars. Towards this aim, we present the results of three projects and discuss another two preliminary studies of further explorations. In so doing, we explore a fairly comprehensive range of possibilities regarding the formation and detection of terrestrial- mass planets in the habitable zone. We first study the potential for terrestrial planets to form in situ in and around the habitable zones of M-dwarf stars. We proceed to explore the feasibility of searches for these planets using the transit method via Monte- Carlo simulations. We find that M-dwarfs pose an interesting challenge for study: being inherently dim, widely spread on the sky, and photometrically variable. We present results of simulated ground-based transit search campaigns as well as simulated searches from a modest satellite mission. Our second project is a straightforward extension of the previous study: a collaborative effort to search for transit signals around the nearest M-dwarf: Proxima Centauri. We describe our observations as well as the Monte-Carlo analysis used to place constraints on the possible planetary radii and periods. Our third project is a search for transiting extra-solar Jovian planets using the Rossiter-McLaughlin effect. We search through the private Keck radial- velocity datasets for undiscovered Rossiter-McLaughlin signals. We present our results in the form of both strong null-result datasets as well as potential transiting systems. We then briefly analyze these larger Jovian planets for potential to harbor potentially habitable terrestrial satellites. Our final preliminary analysis looks into the potential for the Large Synoptic Survey Telescope to detect transiting Neptune-mass planets orbiting M-dwarfs which could then lead to terrestrial-mass planet detections. The sum of these efforts is a comprehensive investigation into the likelihood and feasibility of searching for potentially habitable terrestrial-mass planets around other stars.

  7. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    1998-01-01

    An exotic terrain of wind-eroded ridges and residual smooth surfaces are seen in one of the highest resolution images ever taken of Mars from orbit. The Medusae Fossae formation is believed to be formed of the fragmental ejecta of huge explosive volcanic eruptions. When subjected to intense wind-blasting over hundreds of millions of years, this material erodes easily once the uppermost tougher crust is breached. In the Mars Orbiter Camera (MOC) image shown on the right, the crust, or cap rock, can be seen in the upper right part of the picture. The finely-spaced ridges are similar to features on Earth called yardangs, which are formed by intense winds plucking individual grains from, and by wind-driven sand blasting particles off, sedimentary deposits.

    The MOC image was taken on October 30, 1997 at 11:05 AM PST, shortly after the Mars Global Surveyor spacecraft's 31st closest approach to Mars. The image covers an area 3.6 X 21.5 km (2.2 X 13.4 miles) at 3.6 m (12 feet) per picture element--craters only 11 m (36 feet, about the size of a swimming pool) across can be seen. The context image (left; the best Viking view of the area; VO 1 387S34) has a resolution of 240 m/pixel, or 67 times lower resolution than the MOC frame.

    Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  8. The Tuscaloosa Formation revisited

    SciTech Connect

    Hansley, P.L.

    1996-09-01

    A petrologic study of the Upper Cretaceous lower Tuscaloosa Formation in the Gulf Coast from depths of 2,700 to 6,000 in indicates that anomalously high porosity (>20 percent) in deep gas and condensate-bearing sandstones (5,000 to 6,000 m) is approximately evenly divided between primary and secondary porosity. Primary porosity was preserved by early, iron-rich grain-rimming chlorite and quartz overgrowths. Most secondary porosity resulted from dissolution of carbonate cements. Moldic pores outlined by chlorite were created by dissolution of unstable feldspars and rock fragments. Interparticle clay microporosity is significant in sandstones containing authigenic kaolinite and (or) chlorite. Pores were filled in the deepest sandstones by quartz overgrowths and a late magnesium-rich chlorite that is commonly obscured by fibrous illite. Voids were created in the early Tertiary(?) by acidic meteoric waters and during deep burial by brines carrying organic and inorganic acids that were released during hydrocarbon maturation in neighboring shales. Oil fills dissolution voids in ankerite cement and albitized plagioclase and coats most authigenic minerals. Two-phase primary fluid inclusions in quartz overgrowths which also contain oil-bearing inclusions have homogenization temperatures between 125{degrees}C and 134{degrees}C. These temperatures combined with a burial history reconstruction indicate that hydrocarbons migrated into Tuscaloosa sandstones during the Miocene. Overpressuring began in the middle Tertiary along with gas generation in the Tuscaloosa. These events coincided with the end of deep meteoric flow through the Gulf section and the beginning of a compactional hydrologic regime. Precipitation of quartz overgrowths and hydrocarbons at this time locally created effective pressure seals.

  9. Formative Assessment Probes: Is It a Rock? Continuous Formative Assessment

    ERIC Educational Resources Information Center

    Keeley, Page

    2013-01-01

    A lesson plan is provided for a formative assessment probe entitled "Is It a Rock?" This probe is designed for teaching elementary school students about rocks through the use of a formative assessment classroom technique (FACT) known as the group Frayer Model. FACT activates students' thinking about a concept and can be used to

  10. Formative Assessment Probes: Is It a Rock? Continuous Formative Assessment

    ERIC Educational Resources Information Center

    Keeley, Page

    2013-01-01

    A lesson plan is provided for a formative assessment probe entitled "Is It a Rock?" This probe is designed for teaching elementary school students about rocks through the use of a formative assessment classroom technique (FACT) known as the group Frayer Model. FACT activates students' thinking about a concept and can be used to…

  11. Updated diatom biostratigraphy for Monterey Formation

    SciTech Connect

    Barron, J.A.

    1986-04-01

    Diatom biostratigraphy for the latest early Miocene to earliest Pliocene of California is updated by new correlations to absolute time, and additional secondary datum levels (first and last occurrences) are identified. As yet, late middle Miocene to latest Miocene (14-6 Ma) diatom datum levels have not been correlated directly with magnetic stratigraphy in the northeast Pacific. Absolute ages are estimated indirectly by correlating northeast Pacific diatom datum levels with tropical Pacific diatom datum levels, which are correlated directly with magnetic stratigraphy. DSDP sections in the northeastern Pacific (Sites 470, 472) and northwestern Pacific (Site 438) contain mixtures of tropical and temperate diatom species. Graphical correlation techniques applied to these sections correlate temperate datum levels to tropical datum levels and, hence, to magnetic stratigraphy. Absolute ages for these datum levels are then estimated using magnetic time scales. W.A. Berggren et al suggested a new correlation of magnetic anomaly 5 (8.92-10.42 Ma) with magnetic polarity Chron 11, rather than with Chron 9. Significant changes in absolute age estimates from late middle Miocene to early late Miocene diatom zones and subzones are as follows: base of Denticulopsis hustedtii-D. lauta zone = 13.8 Ma; base of subzone b = 12.7 Ma; base of subzone c = 11.4 Ma; base of subzone d = 8.9 Ma; base of D. hustedtii zone = 8.4 Ma; top of D. hustedtii zone (base of Thalassiosira antiqua zone) = 7.6 Ma. Graphical correlation techniques have been applied to stratigraphic sections from Newport Beach, Naples coastal bluffs, Lompoc, Monterey, and the type Luisian area near Paso Robles, as well as from DSDP Sites 173, 468, 469, and 470, and have identified 31 secondary diatom datums and 4 silicoflagellate datums that are the most useful for correlations.

  12. Formation of interstellar anions

    NASA Astrophysics Data System (ADS)

    Senent, Maria Luisa

    2012-05-01

    Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H ? CnH and Cn- +H ? CnH-) and associative detachment processes (Cn- +H ? CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Mass, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Mass, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M.L.Senent, N.Feautrier, Chem. Phys. Lett., 533, 6 (2012) [11] M.L.Senent, M.Hochlaf, submitted

  13. The formation of Pangea

    NASA Astrophysics Data System (ADS)

    Stampfli, G. M.; Hochard, C.; Vérard, C.; Wilhem, C.; vonRaumer, J.

    2013-05-01

    The making of Pangea is the result of large-scale amalgamation of continents and micro-continents, which started at the end of the Neoproterozoic with the formation of Gondwana. As pieces were added to Gondwana on its South-American, Antarctica and Australia side, ribbon-like micro-continents were detached from its African and South-Chinese side: Cadomia in the late Neoproterozoic, Avalonia and Hunia in the Ordovician, Galatia in the Devonian and Cimmeria in the Permian. Cadomia was re-accreted to Gondwana, but the other ribbon-continents were accreted to Baltica, North-China, Laurussia or Laurasia. Finding the origin of these numerous terranes is a major geological challenge. Recently, a global plate tectonic model was developed together with a large geological/geodynamic database, at the Lausanne University, covering the last 600 Ma of the Earth's history. Special attention was given to the placing of Gondwana derived terranes in their original position, using all possible constraints. We propose here a solution for the Variscan terranes, another paper deals with the Altaids. The Galatian super-terrane was detached from Gondwana in the Devonian, during the opening of Paleotethys, and was quickly separated into four sub-terranes that started to by-pass each other. The leading terranes collided at the end of the Devonian with the Hanseatic terrane detached from Laurussia. In the Carboniferous, Gondwana started to impinge onto the amalgamated terranes, creating the Variscan chain and the Pangean super-continent. East of Spain Paleotethys remained opened until the Triassic, subducting northward under Laurasia. Roll-back of the Paleotethyan slab triggered the collapse of most of the European Variscan orogen, which was replaced by series of Permian rifts, some of them becoming oceanized back-arc basins during the Triassic. Major force changes at the Pangean plate limits at the end of the Triassic provoked its break-up, through the opening of the proto-Caribbean, central-Atlantic, Alpine-Tethys oceanic seaways.

  14. Portable File Format (PFF) specifications.

    SciTech Connect

    Dolan, Daniel H.,

    2015-02-01

    Created at Sandia National Laboratories, the Portable File Format (PFF) allows binary data transfer across computer platforms. Although this capability is supported by many other formats, PFF files are still in use at Sandia, particularly in pulsed power research. This report provides detailed PFF specifications for accessing data without relying on legacy code.

  15. Developing the Common Communication Format.

    ERIC Educational Resources Information Center

    Hopkinson, Alan

    1986-01-01

    Outlines history of the development of the Unesco Common Communication Format, which is designed to enable exchange of records (monographs, serials, journal articles, contributions in proceedings) between different agencies throughout the world. Highlights include definition of "exchange format," major technical features, and examples of current

  16. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying it. Formats can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). As w...

  17. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying it. Formats can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). As ...

  18. Planet formation around millisecond pulsars

    NASA Technical Reports Server (NTRS)

    Banit, Menashe; Ruderman, Malvin; Shaham, Jacob

    1993-01-01

    We present a model for the formation of planets in circular orbits around millisecond pulsars. We propose that the planets originate from a circumbinary excretion disk around a binary millisecond pulsar and show how physical conditions in such a disk lead to the eventual formation of planets.

  19. The Principal as Formative Coach

    ERIC Educational Resources Information Center

    Nidus, Gabrielle; Sadder, Maya

    2011-01-01

    Formative coaching, an approach that uses student work as the foundation for mentoring and professional development, can help principals become more effective instructional leaders. In formative coaching, teaches and coaches analyze student work to determine next steps for instruction. This article shows how a principal can use the steps of the

  20. Motivating Students through Formative Feedback

    ERIC Educational Resources Information Center

    Mauch, Lois

    2007-01-01

    Technology tools that are used to help apply standards and benchmarks motivate physical educators to use new methods of teaching, and create new ways to provide students with direct formative feedback, the number one motivator for students. Direct formative feedback refers to verbal communication between the teacher and/or parent and student. The

  1. Star formation in the multiverse

    SciTech Connect

    Bousso, Raphael; Leichenauer, Stefan

    2009-03-15

    We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

  2. The Apennine Bench Formation revisited

    NASA Technical Reports Server (NTRS)

    Spudis, P. D.; Hawke, B. R.

    1985-01-01

    The Apennine Bench Formation consists of pre-mare light plains materials that crop out south of the crater Archimedes, inside the Imbrium basin. This material was ascribed to either impact or volcanic origins. The characteristics of Apollo 15 KREEP basalts and the Apennine Bench Formation are reviewed to determine whether their characteristics are compatible with a volcanic origin.

  3. Flowstone Formations in Jewel Cave

    USGS Multimedia Gallery

    Jewel Cave is currently the 3rd most extensive cave network in the world. It is believed to have formed completely underwater, thus leading to the extensive coating of calcite crystals. In the center of the image, a formation known as flowstone can be seen. Flowstone is a type of calcite formation ...

  4. FORMATION OF SECONDARY ORGANIC AEROSOL

    EPA Science Inventory

    (1) Gas-phase chemistry. With the clear and profound effect of the VOC/NOx ratio on SOA formation, we will augment gas-phase VOC oxidation mechanisms in atmospheric models to account for the effect of NOx level on the mechanism of SOA formation; (2) Revis...

  5. Cyanide Formation by Chromobacterium violaceum

    PubMed Central

    Michaels, Ruth; Corpe, W. A.

    1965-01-01

    Michaels, Ruth (Columbia University, New York, N.Y.), and W. A. Corpe. Cyanide formation by Chromobacterium violaceum. J. Bacteriol. 89:106112. 1965.The formation of cyanide by a Chromobacterium violaceum strain was studied with growing cultures and with nonproliferating cells grown in complex and chemically defined media. Most of the cyanide was produced during the log-phase growth of the organism, and accumulated in the culture supernatant fluid. A synergistic effect of glycine and methionine on cyanide formation in a chemically defined medium was observed, and the amount of cyanide formed was found to be dependent on the concentrations of the two substances. Cyanide formation by nonproliferating cells was stimulated by preincubation with glycine and methionine. Cyanide formation by adapted cells in the presence of glycine and methionine was stimulated by succinate, malate, or fumarate, and depressed by azide and 2,4-dinitrophenol. Methionine could be replaced by betaine, dimethylglycine, and choline. PMID:14255648

  6. Physics of primordial star formation

    NASA Astrophysics Data System (ADS)

    Yoshida, Naoki

    2012-09-01

    The study of primordial star formation has a history of nearly sixty years. It is generally thought that primordial stars are one of the key elements in a broad range of topics in astronomy and cosmology, from Galactic chemical evolution to the formation of super-massive blackholes. We review recent progress in the theory of primordial star formation. The standard theory of cosmic structure formation posits that the present-day rich structure of the Universe developed through gravitational amplification of tiny matter density fluctuations left over from the Big Bang. It has become possible to study primordial star formation rigorously within the framework of the standard cosmological model. We first lay out the key physical processes in a primordial gas. Then, we introduce recent developments in computer simulations. Finally, we discuss prospects for future observations of the first generation of stars.

  7. A format for phylogenetic placements.

    PubMed

    Matsen, Frederick A; Hoffman, Noah G; Gallagher, Aaron; Stamatakis, Alexandros

    2012-01-01

    We have developed a unified format for phylogenetic placements, that is, mappings of environmental sequence data (e.g., short reads) into a phylogenetic tree. We are motivated to do so by the growing number of tools for computing and post-processing phylogenetic placements, and the lack of an established standard for storing them. The format is lightweight, versatile, extensible, and is based on the JSON format, which can be parsed by most modern programming languages. Our format is already implemented in several tools for computing and post-processing parsimony- and likelihood-based phylogenetic placements and has worked well in practice. We believe that establishing a standard format for analyzing read placements at this early stage will lead to a more efficient development of powerful and portable post-analysis tools for the growing applications of phylogenetic placement. PMID:22383988

  8. Toxicokinetics of formate during hemodialysis.

    PubMed

    Jacobsen, D; Ovreb, S; Sejersted, O M

    1983-01-01

    During hemodialysis in a methanol poisoned patient, formate elimination followed first order kinetics with a plasma half-life of formate of 165 min. The mean dialysator (1.6 m2) clearance of formate was 148 ml/min (n = 8, SD +/- 11, range 128-161) at a blood flow of 215 ml/min. By applying first order kinetics, a volume of distribution of 0.5 l/kg was found, assuming that the dialysator clearance equals the total body clearance of formate. Formate, the main toxic agent in methanol poisoning, is thus probably more effectively removed by hemodialysis than methanol. This fact, and the very slow endogenous methanol elimination during appropriate ethanol treatment, should be considered when deciding on the treatment of a methanol poisoned patient presenting with metabolic acidosis. PMID:6660049

  9. Liquid HEC formation damage potential

    SciTech Connect

    Ali, S.A.; Sketchler, B.C. ); Hashemi, R. )

    1994-11-01

    Hydroxyethylcellulose (HEC) polymer is used extensively in completion/workover operations as a viscosifying agent for gravel-pack carrier fluid and fluid-loss-control pills. Formation damage potential of HEC gels is typically attributed to the presence of fisheyes or microgels. Potential for fisheye- and microgel-formation damage can be minimized by keeping powder dry to prevent water absorption and consequent hydration of the outer polymer layer that would prevent full polymer solution. To avoid problems in dry-powder storage and handling, HEC powder is sometimes pre-dispersed in alcohols, kerosene, diesel or mineral oil. These formulations are known as liquid HEC. Although they prevent premature powder hydration and consequent fisheye formation, they are not effective against formation damage because they contain microgels that are often pre-existing in the HEC powder used to prepare the slurry. In addition, these formulations may not be as clean as the HEC oilfield applications require, and may contain other additives which can, in some instances, react with the polymer. While the formation damage potential of HEC gels mixed in the field from HEC powder is well recognized, the damage potential of pre-mixed liquid HEC is less known. Hayatdavoudi, et al., noted that the gel prepared with liquid HEC contained as much microgels as those prepared using HEC powder. Chauveteau and Kohler reported that microgels can build up on the formation surface, as well as invade the formation and clog pores.

  10. Dissipative processes in galaxy formation.

    PubMed Central

    Silk, J

    1993-01-01

    A galaxy commences its life in a diffuse gas cloud that evolves into a predominantly stellar aggregation. Considerable dissipation of gravitational binding energy occurs during this transition. I review here the dissipative processes that determine the critical scales of luminous galaxies and the generation of their morphology. The universal scaling relations for spirals and ellipticals are shown to be sensitive to the history of star formation. Semiphenomenological expressions are given for star-formation rates in protogalaxies and in starbursts. Implications are described for elliptical galaxy formation and for the evolution of disk galaxies. PMID:11607396

  11. Dynamics of rock varnish formation

    SciTech Connect

    Raymond, R. Jr.; Reneau, S.L.; Guthrie, G.D. Jr.; Bish, D.L.; Harrington, C.D.

    1991-01-01

    Our studies of rock varnish from the southwestern United States suggest that the Mn-phase in rock varnish has neither the chemistry nor the crystal structure of birnessite. Rather, the Mn-rich phase is non-crystalline and contains Ba, Ca, Fe, Al, and P. Unknowns concerning the formation of this non-crystalline Mn phase must be resolved before researchers are able to define chemical parameters of rock varnish formation based upon conditions of formation of the Mn phase. 6 refs., 9 figs.

  12. Treating fines containing earthen formations

    SciTech Connect

    Watkins, D. R.; Kalfayan, L. J.; Knight, R. K.; Young, D. C.

    1985-10-29

    Method for treating earthen formations which contain water-sensitive, finely divided particulate matter wherein there is injected into the formation steam or a mixture of steam and hot water containing an effective fines-stabilizing amount of a compound containing ammoniacal nitrogen selected from the group consisting of ammonium hydroxide, an ammonium salt of an inorganic acid, an ammonium salt of a carboxylic acid, ammonium cyanate, derivatives of ammonium cyanate, ammonium thiocyanate, and a water-soluble ammonia or ammonium ion precursor selected from the group consisting of amides of carbamic acid and thiocarbamic acid, derivatives of such amides, tertiary carboxylic acid amides and their substituted and akylated derivatives. Preferred additives include ammonium carbonate and urea. If the formation is a subsurface oil-containing formation, the treatment can be part of a method for enhanced oil recovery.

  13. Sandstone Formations in Capitol Reef

    USGS Multimedia Gallery

    Capitol Reef is primarily made up of sandstone formations within the Waterpocket Fold, monocline that extends nearly 100 miles. A monocline is a step-like fold in rock strata that can resemble an enormous wrinkle in the earth....

  14. Method for treating underground formations

    SciTech Connect

    Noles, J.R.; Walker, C.O.; White, N.F.

    1981-04-14

    Disclosed is a method for treating subterranean formations such as underground petroleum-containing formations penetrated by a well, and particularly a formation penetrated by a producing well which formation contain a plurality of zones, one or more of which are producing petroleum and one or more of which are producing water. The treatment selectively reduces the permeability of the water-producing intervals without adversely affecting the permeability of the oil producing intervals, thereby reducing the production of water and reducing the water-oil ratio of the fluid being produced from the well. The treatment method involves introducing an effective amount of a liquid comprising a hydrocarbon having dispersed therein an unhydrated water swellable clay such as bentonite, a sodium montmorillonite. The clay swells on contacting water in the water-producing intervals and plugs or reduces the permeability of the flow channels in the water-producing intervals.

  15. Vertical formations demand unique treatments

    SciTech Connect

    Fairchild, K.

    1996-04-01

    In the US midcontinent area, major thrust faults trap large quantities of hydrocarbons in the down-thrown fault block. As exploration of these thrust fault structures continues, the application of extended reach and horizontal well bores will increase. Formations in deep structures are apt to have lower porosity and permeability than the currently developed thrust faults and thus, require fracture stimulation. In addition, the portion of the formation closest to the fault may be subjected to folding resulting in a vertical formation penetrated by a horizontal well bore. Low porosity and vertical bedding were encountered in the City of Lawton No. 1-34, an 18,088-ft wildcat (14,627-ft TVD) in Caddo County, Oklahoma. This article details methods to overcome the obstacles that well bore and formation geometry present to fracture stimulation operations in the 17,714-ft (14,614-ft TVD) Britt sand.

  16. Motivational Determinants of Coalition Formation

    ERIC Educational Resources Information Center

    Folkes, Valerie S.; Weiner, Bernard

    1977-01-01

    Coalition preferences of 300 male and female subjects were ascertained under varying motivational conditions. Demonstrates that coalition formation and interpersonal conflict are dependent upon the motivational determinants of group activity. (Editor/RK)

  17. Micromagnetosphere Formation on the Moon

    NASA Astrophysics Data System (ADS)

    Zimmerman, M. I.; Farrell, W. M.; Poppe, A. R.

    2015-10-01

    Kinetic simulations of the solar wind's interaction with lunar crustal magnetic fields reveal formation of micromagnetospheres where ions are deflected by strong electric fields. Future missions should measure magnetic field structure at the ground.

  18. The Portable Document Format - PDF.

    PubMed

    Grech, V

    2002-04-01

    This article demonstrates how documents prepared in hypertext or word processor format can be saved in portable document format (PDF). These files are self-contained documents that that have the same appearance on screen and in print, regardless of what kind of computer or printer are used, and regardless of what software package was originally used to for their creation. PDF files are compressed documents, invariably smaller than the original files, hence allowing rapid dissemination and download. PMID:22368611

  19. Immigration, Integration and Ghetto Formation

    NASA Astrophysics Data System (ADS)

    Meyer-Ortmanns, Hildegard

    We study ghetto formation in a population with natives and immigrants in the framework of the two-dimensional Ising-model with Kawasaki-exchange dynamics. It is the phase structure of the Ising model, the integration speed and the immigration rate which determine whether ghetto formation between natives and immigrants can be avoided or not. Our simulations are performed in- and out-of-equilibrium.

  20. Cosmic strings and galaxy formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  1. Star Formation Across Galactic Environments

    NASA Astrophysics Data System (ADS)

    Young, Jason

    2013-01-01

    I present here parallel investigations of star formation in AGN-free and quasar host galaxies. These environments are both insightful; quasars are among the most violent objects known, reshaping their host galaxies, while my sample of AGN-free star-forming galaxies ranges from systems larger than the Milky Way to dwarf star-forming galaxies. The AGN-free galaxies are drawn from the KPNO International Spectroscopic Survey, an Hα-selected, volume-limited survey was designed to avoid continuum luminosity bias. This work studies the KISS galaxies in mid- and far-IR using Spitzer IRAC and MIPS photometry. These IR bands are interesting because the UV light from young stars is reprocessed into thermal emission in the far-IR (24μm MIPS) by dust and into vibrational transition features in the mid-IR (8.0μm IRAC) by polycyclic aromatic hydrocarbons (PAHs). This work examines the efficiencies of PAH and dust emission as tracers of star-formation. I find that the efficiency of PAH as a star-formation tracer varies with galactic stellar mass, while thermal dust has no systematic dependance on galactic mass. My study of quasar host galaxies utilizes images of eight PG quasars from the WFPC2 and NICMOS instruments aboard HST. I use narrow-band images centered on the Hβ, [OII]λ3727, [OIII]λ5007, and Paα emission lines to construct extinction and star formation maps. Additionally, I use line-ratio maps to distinguish AGN-powered line emission from star formation powered line emission. I find star formation, albeit at rates are lower than expected, suggesting that quasar host galaxies are dynamically more advanced than suspected. Seven of the galaxies have higher mass-specific star-formation rates. Additionally, I see evidence of shocked gas, supporting the hypotheses from earlier works that AGN activity quenches star formation in host galaxies by disrupting gas reservoirs.

  2. Thiol isomerases in thrombus formation

    PubMed Central

    Furie, Bruce; Flaumenhaft, Robert

    2014-01-01

    Protein disulfide isomerase, ERp5 and ERp57, among perhaps other thiol isomerases, are important for the initiation of thrombus formation. Using the laser injury thrombosis model in mice to induce in vivo arterial thrombus formation, it was shown that thrombus formation is associated with PDI secretion by platelets, that inhibition of PDI blocked platelet thrombus formation and fibrin generation, and that endothelial cell activation leads to PDI secretion. Similar results using this and other thrombosis models in mice have demonstrated the importance of ERp5 and ERp57 in the initiation of thrombus formation. The integrins ?IIb?3 and ?V?3 play a key role in this process and interact directly with PDI, ERp5 and ERp57. The mechanism by which thiol isomerases participate in thrombus generation is being evaluated using trapping mutant forms to identify substrates of thiol isomerases that participate in the network pathways linking thiol isomerases, platelet receptor activation and fibrin generation. Protein disulfide isomerase as an antithrombotic target is being explored using isoquercetin and quercetin 3-rutinoside, inhibitors of PDI identified by high throughput screening. Regulation of thiol isomerase expression, analysis of the storage and secretion of thiol isomerases and determination of the electron transfer pathway are key issues to understanding this newly discovered mechanism of regulation of the initiation of thrombus formation. PMID:24677236

  3. Degeneracies of galaxy formation models

    NASA Astrophysics Data System (ADS)

    Wang, Lan

    2015-08-01

    The current models of galaxy formation and evolution have achieved many successes. However, the detail descriptions on different physical processes still have a lot of uncertainties, and degeneracies exist among these processes in reproducing observational statistics of galaxies. For example, for semi-analytic galaxy formation models, modification to the star formation law has similar effect as increasing supernovae feedback, in suppressing star formation in low mass galaxies in low redshift to match observation. Even when the relations between galaxy stellar mass and its host dark matter halo mass in different models show the same median relation, how galaxies populate the scatters of the relation can result to different galaxy clustering properties, due to the detail dependence of galaxy stellar mass on halo formation time. Apart from the degeneracies of physical processes, cosmology also adds degeneracy in the picture of galaxy formation. Warm dark matter and cold dark matter cosmologies result to similar galaxy properties of many aspects that are difficult to be distinguished within current observational accuracy.

  4. Treating tar sands formations with karsted zones

    SciTech Connect

    Vinegar, Harold J.; Karanikas, John Michael

    2010-03-09

    Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

  5. Isolated star formation: from cloud formation to core collapse.

    PubMed

    Ward-Thompson, Derek

    2002-01-01

    The formation of stars is one of the most fundamental problems in astrophysics, as it underlies many other questions, on scales from the formation of galaxies to the formation of the solar system. The physical processes involve the turbulent behavior of a partially ionized medium containing a non-uniform magnetic field. Current debate centers around the time taken for turbulence to decay and the relative importance of the roles played by magnetic fields and turbulence. Technological advances such as millimeter-wave cameras have made possible observations of the temperature and density profiles, and statistical calculations of the lifetimes, of objects collapsing under their own self-gravity and those on the verge of collapse. Increased computing power allows more complex models to be made that include magnetic and turbulent effects. No current model can reproduce all of the observations. PMID:11778038

  6. The Dynamics of Latifundia Formation

    PubMed Central

    Chaves, Luis Fernando

    2013-01-01

    Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia. PMID:24376597

  7. Significant melting of ice-wedges and formation of thermocirques on hill-slopes of thermokarst lakes in Central Yakutia (Siberia)

    NASA Astrophysics Data System (ADS)

    Sjourn, Antoine; Costard, Franois; Gargani, Julien; Fedorov, Alexander; Skorve, Johnny

    2013-04-01

    On Earth, permafrost containing a high ice volume (referred as ice-rich) are sensible to climate change, they have been regionally degraded (thermokarst) during the early Holocene climatic optimum forming numerous thermokarst lakes in Central Yakutia (eastern Siberia). Recent temperature increases in the Arctic and Subarctic have been significantly greater than global averages. The frequency and magnitude of terrain disturbances associated with thawing permafrost are increasing in these regions and are thought to intensify in the future. Therefore, understand how is the current development of thermokarst is a critical question. Here, we describe the significant melting of ice-wedges on slopes of thermokarst lakes that leads to formation of amphitheatrical hollows referred as thermocirques. The evolution of thermocirques in Central Yakutia has been little studied and analyzing their formation could help to understand the recent thermokarst in relation to climate change in Central Yakutia. We studied the thermocirques at two scales: (i) field surveys of different thermocirques in July 2009-2010 and October 2012 to examine the processes and origin of melting of ice-wedges and; (ii) photo-interpretation of time series of satellite images (KH-9 Hexagon images of 6-9 m/pixel and GeoEye images of 50 cm/pixel) to study the temporal evolution of thermocirques. The melting of ground-ice on the scarp of thermocirque triggers falls and small mud-flows that induce the retreat of the scarp parallel to itself. Based on field studies and on GeoEye image comparison, we show that their rate of retrogressive growth is 1-2 m/year. On the hill-slopes of lakes, the thermokarst could be initiated by different processes that lead to the uncover and then melting of ice-wedges: thermal erosion by the waves of the ice-rich bluff; active-layer detachment (a form of slope failure linked to detachment of the seasonally thawed upper ground); flowing of water on the slope (precipitation) or; increase of near-surface temperature (insolation, summer temperature). We suggest that the preferential occurrence of thermocirques on south-facing slopes of lakes could emphasize the role of insolation as a factor controlling the preferential melting of ice-wedges. The air temperatures are shown to have increased in Central Yakutia over years and deciphering if ongoing climate warming could lead to an increased development of thermocirques along lake slopes in Central Yakutia is a question that we will address in future study.

  8. Formation of Molecular Clouds and Global Conditions for Star Formation

    NASA Astrophysics Data System (ADS)

    Dobbs, C. L.; Krumholz, M. R.; Ballesteros-Paredes, J.; Bolatto, A. D.; Fukui, Y.; Heyer, M.; Low, M.-M. M.; Ostriker, E. C.; Vzquez-Semadeni, E.

    Giant molecular clouds (GMCs) are the primary reservoirs of cold, star-forming molecular gas in the Milky Way and similar galaxies, and thus any understanding of star formation must encompass a model for GMC formation, evolution, and destruction. These models are necessarily constrained by measurements of interstellar molecular and atomic gas and the emergent, newborn stars. Both observations and theory have undergone great advances in recent years, the latter driven largely by improved numerical simulations, and the former by the advent of large-scale surveys with new telescopes and instruments. This chapter offers a thorough review of the current state of the field.

  9. Review of nutrition labeling formats.

    PubMed

    Geiger, C J; Wyse, B W; Parent, C R; Hansen, R G

    1991-07-01

    This article examines nutrition labeling history as well as the findings of nine research studies of nutrition labeling formats. Nutrition labeling regulations were announced in 1973 and have been periodically amended since then. In response to requests from consumers and health care professionals for revision of the labeling system, the Food and Drug Administration initiated a three-phase plan for reform of nutrition labeling in 1990. President Bush signed the Nutrition Labeling and Education Act in November 1990. Literature analysis revealed that only nine studies with an experimental design have focused on nutrition labeling since 1971. Four were conducted before 1975, which was the year that nutrition labeling was officially implemented, two were conducted in 1980, and three were conducted after 1986. Only two of the nine studies supported the traditional label format mandated by the Code of Federal Regulations, and one study partially supported it. Four of the nine studies that evaluated graphic presentations of nutrition information found that consumer comprehension of nutrition information was improved with a graphic format for nutrition labeling: three studies supported the use of bar graphs and one study supported the use of a pie chart. Full disclosure (ie, complete nutrient and ingredient labeling) was preferred by consumers in two of the three studies that examined this variable. The third study supported three types of information disclosure dependent upon socioeconomic class. In those studies that tested graphics, a bar graph format was significantly preferred and showed better consumer comprehension than the traditional format. PMID:2071796

  10. Modeling of Mitochondrial Donut Formation.

    PubMed

    Long, Qi; Zhao, Danyun; Fan, Weimin; Yang, Liang; Zhou, Yanshuang; Qi, Juntao; Wang, Xin; Liu, Xingguo

    2015-09-01

    Mitochondria are highly dynamic cell organelles. Continual cycles of fusion and fission play an important role in mitochondrial metabolism and cellular signaling. Previously, a novel mitochondrial morphology, the donut, was reported in cells after hypoxia-reoxygenation or osmotic pressure changes. However, the mechanism of donut formation remained elusive. Here, we obtained the distribution of donut diameters (D = 2R) and found that 95% are >0.8 ?m. We also performed highly precise measurements of the mitochondrial tubule diameters using superresolution and electron microscopy. Then, we set up a model by calculating the mitochondrial bending energy and osmotic potential during donut formation. It shows that the bending energy is increased as the radius of curvature, R, gets smaller in the process of donut formation, especially for radii <0.4 ?m, creating a barrier to donut formation. The calculations also show that osmotic potential energy release can balance the rising bending energy through volume expansion. Finally, we revealed the donut formation process in a Gibbs free-energy-dependent model combining calculations and measurements. PMID:26331247

  11. Formate dehydrogenase of Clostridium pasteurianum.

    PubMed Central

    Liu, C L; Mortenson, L E

    1984-01-01

    Formate dehydrogenase was purified to electrophoretic homogeneity from N2-fixing cells of Clostridium pasteurianum W5. The purified enzyme has a minimal Mr of 117,000 with two nonidentical subunits with molecular weights of 76,000 and 34,000, respectively. It contains 2 mol of molybdenum, 24 mol of nonheme iron, and 28 mol of acid-labile sulfide per mol of enzyme; no other metal ions were detected. Analysis of its iron-sulfur centers by ligand exchange techniques showed that 20 iron atoms of formate dehydrogenase can be extruded as Fe4S4 centers. Fluorescence analysis of its isolated molybdenum centers suggests it is a molybdopterin. The clostridial formate dehydrogenase has a pH optimum between 8.3 and 8.5 and a temperature optimum of 52 degrees C. The Km for formate is 1.72 mM with a Vmax of 551 mumol of methyl viologen reduced per min per mg of protein. Sodium azide competes competitively with formate (K1 = 3.57 microM), whereas the inactivation by cyanide follows pseudo-first-order kinetics with K = 5 X 10(2) M-1 s-1. PMID:6547435

  12. The Physics of Planetesimal Formation

    NASA Astrophysics Data System (ADS)

    Simon, Jacob; Armitage, Philip; Youdin, Andrew; Li, Rixin

    2015-12-01

    Planetesimals are the precursors to planets, and understanding their formation is an essential step towards developing a complete theory of planet formation. For small solid particles (e.g., dust grains) to coagulate into planetesimals, however, requires that these particles grow beyond centimeter sizes; with traditional coagulation physics, this is very difficult. The streaming instability, which is a clumping process akin to the pile-up of cars in a traffic jam, generates sufficiently high solid densities that the mutual gravity between the clumped particles eventually causes their collapse towards planetesimal mass and size scales. Exploring this transition from dust grains to planetesimals is still in its infancy but is extremely important if we want to understand the basics of planet formation. Here, I present a series of high resolution, first principles numerical simulations of potoplanetary disk gas and dust to study the clumping of particles via the streaming instability and the subsequent collapse towards planetesimals. These simulations have been employed to characterize the planetesimal population as a function of radius in protoplanetary disks. The results of these simulations will be crucial for planet formation models to correctly explain the formation and configuration of solar systems.

  13. STAR FORMATION IN ATOMIC GAS

    SciTech Connect

    Krumholz, Mark R.

    2012-11-01

    Observations of nearby galaxies have firmly established, over a broad range of galactic environments and metallicities, that star formation occurs exclusively in the molecular phase of the interstellar medium (ISM). Theoretical models show that this association results from the correlation between chemical phase, shielding, and temperature. Interstellar gas converts from atomic to molecular only in regions that are well shielded from interstellar ultraviolet (UV) photons, and since UV photons are also the dominant source of interstellar heating, only in these shielded regions does the gas become cold enough to be subject to Jeans instability. However, while the equilibrium temperature and chemical state of interstellar gas are well correlated, the timescale required to reach chemical equilibrium is much longer than that required to reach thermal equilibrium, and both timescales are metallicity-dependent. Here I show that the difference in timescales implies that, at metallicities below a few percent of the solar value, well shielded gas will reach low temperatures and proceed to star formation before the bulk of it is able to convert from atomic to molecular. As a result, at extremely low metallicities, star formation will occur in a cold atomic phase of the ISM rather than a molecular phase. I calculate the observable consequences of this result for star formation in low-metallicity galaxies, and I discuss how some current numerical models for H{sub 2}-regulated star formation may need to be modified.

  14. SW New Mexico Oil Well Formation Tops

    SciTech Connect

    Shari Kelley

    2015-10-21

    Rock formation top picks from oil wells from southwestern New Mexico from scout cards and other sources. There are differing formation tops interpretations for some wells, so for those wells duplicate formation top data are presented in this file.

  15. Gypsum Layer in Spearfish Formation, SD

    USGS Multimedia Gallery

    Spearfish Formation near Spearfish, SD. The Spearfish Formation is a red, silty shale with interbedded red sandstone and siltstone. The formation contains massive gypsum deposits, which is the white layer in the photograph....

  16. Computational Modeling of Microabscess Formation

    PubMed Central

    Pigozzo, Alexandre Bittencourt; Macedo, Gilson Costa; Weber dos Santos, Rodrigo; Lobosco, Marcelo

    2012-01-01

    Bacterial infections can be of two types: acute or chronic. The chronic bacterial infections are characterized by being a large bacterial infection and/or an infection where the bacteria grows rapidly. In these cases, the immune response is not capable of completely eliminating the infection which may lead to the formation of a pattern known as microabscess (or abscess). The microabscess is characterized by an area comprising fluids, bacteria, immune cells (mainly neutrophils), and many types of dead cells. This distinct pattern of formation can only be numerically reproduced and studied by models that capture the spatiotemporal dynamics of the human immune system (HIS). In this context, our work aims to develop and implement an initial computational model to study the process of microabscess formation during a bacterial infection. PMID:23197993

  17. Biofilm formation by Clostridium difficile

    PubMed Central

    Dapa, Tanja; Unnikrishnan, Meera

    2013-01-01

    Clostridium difficile infection (CDI) is a major healthcare-associated disease worldwide. Recurring infections and increasing antibiotic resistance have complicated treatment of CDI. While C. difficile spores are important for transmission and persistence of CDI, other factors such as gut colonization and formation of bacterial communities in the gut may also contribute to pathogenesis and persistence, but have not been well investigated. Recently, we reported that important clinical C. difficile strains are able to form composite biofilms in vitro. C. difficile biofilm formation is a complex process, modulated by several different factors, including cell surface components and regulators. We also reported that bacteria within biofilms are more resistant to high concentrations of vancomycin, the antibiotic of choice for treatment of CDI. Here we summarize our recent findings and discuss the implications of biofilm formation by this anaerobic gut pathogen in disease pathogenesis and treatment. PMID:23892245

  18. Granuloma Formation in Pulmonary Sarcoidosis

    PubMed Central

    Broos, Caroline E.; van Nimwegen, Menno; Hoogsteden, Henk C.; Hendriks, Rudi W.; Kool, Mirjam; van den Blink, Bernt

    2013-01-01

    Sarcoidosis is a granulomatous disorder of unknown cause, affecting multiple organs, but mainly the lungs. The exact order of immunological events remains obscure. Reviewing current literature, combined with careful clinical observations, we propose a model for granuloma formation in pulmonary sarcoidosis. A tight collaboration between macrophages, dendritic cells, and lymphocyte subsets, initiates the first steps toward granuloma formation, orchestrated by cytokines and chemokines. In a substantial part of pulmonary sarcoidosis patients, granuloma formation becomes an on-going process, leading to debilitating disease, and sometimes death. The immunological response, determining granuloma sustainment is not well understood. An impaired immunosuppressive function of regulatory T cells has been suggested to contribute to the exaggerated response. Interestingly, therapeutical agents commonly used in sarcoidosis, such as glucocorticosteroids and anti-TNF agents, interfere with granuloma integrity and restore the immune homeostasis in autoimmune disorders. Increasing insight into their mechanisms of action may contribute to the search for new therapeutical targets in pulmonary sarcoidosis. PMID:24339826

  19. Terrestrial versus giant planet formation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1988-01-01

    Given a solar nebular surrounding the early protosun, containing dust grains that have already undergone growth through collisions to about centimeter-size, the question of the formation of the terrestrial and giant planets is considered. In contrast to the usual approach of emphasizing how well a problem is understood, the uncertainties and areas where more work needs to be done will be accentuated. Also, the emphasis will be on the dynamics of planetary formation, because profound problems still exist in this area, and because it seems most logical to concentrate first on the dynamical questions involved with assembling the planets before putting too much effort into the detailed chemical and geological consequences of certain formation mechanisms.

  20. Theories of Giant Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets, is presented. The most detailed models are based upon observations of our own Solar System and of young stars and their environments. While these models predict that rocky planets should form around most single stars, the frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Most models for extrasolar giant planets suggest that they formed as did Jupiter and Saturn (in nearly circular orbits, far enough from the star that ice could), and subsequently migrated to their current positions, although some models suggest in situ formation.

  1. Star formation in unperturbed LIRGs

    NASA Astrophysics Data System (ADS)

    Fuentes-Carrera, I.; Olgun, L.; Ambrocio-Cruz, P.; Verley, S.; Rosado, M.; Verdes-Montenegro, L.; Repetto, P.; Vzquez, C.; Aguilera, V.

    2011-10-01

    Luminous infrared galaxies (LIRGs) are galaxies with L_{FIR} > 10^11 L_{sun} (Sanders & Mirabel 1996). For a star-forming galaxy to emit at a LIRG level, it must have a very high star formation rate (SFR). In the local Universe, the star formation (SF) is primarily triggered by interactions. However, at intermediate redshift, a large fraction of LIRGs are disk galaxies with little sign of recent merger activity (Zheng et al. 2004). The question arises whether the intermediate redshift LIRGs are ``triggered'' or experiencing ``normal'', if elevated, SF. Understanding these SF processes is important since this type of systems may have contributed to 20% or more of the cosmic star-formation rate in the early Universe (Blain & Phillips 2002).

  2. Physicochemical regulation of biofilm formation

    PubMed Central

    Renner, Lars D.; Weibel, Douglas B.

    2011-01-01

    This article reviews the physical and chemical constraints of environments on biofilm formation. We provide a perspective on how materials science and engineering can address fundamental questions and unmet technological challenges in this area of microbiology, such as biofilm prevention. Specifically, we discuss three factors that impact the development and organization of bacterial communities. (1) Physical properties of surfaces regulate cell attachment and physiology and affect early stages of biofilm formation. (2) Chemical properties influence the adhesion of cells to surfaces and their development into biofilms and communities. (3) Chemical communication between cells attenuates growth and influences the organization of communities. Mechanisms of spatial and temporal confinement control the dimensions of communities and the diffusion path length for chemical communication between biofilms, which, in turn, influences biofilm phenotypes. Armed with a detailed understanding of biofilm formation, researchers are applying the tools and techniques of materials science and engineering to revolutionize the study and control of bacterial communities growing at interfaces. PMID:22125358

  3. A New Spoke Formation Model

    NASA Astrophysics Data System (ADS)

    Jones, G. H.; Krupp, N.; Krueger, H.; Roussos, E.; Ip, W.; Mitchell, D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Fraenz, M.; Dougherty, M. K.; Arridge, C. S.; McAndrews, H. J.

    2006-12-01

    A new model is proposed for the formation of spokes in Saturn's rings. We contend that they are formed by the electrostatic charging of sub-micron ring particles by magnetic field-aligned electron beams originating in Saturn's atmosphere. The existence of these beams has recently been confirmed by the MIMI instrument aboard Cassini. Although observed by MIMI outside the main ring system, the beams are also expected to occur closer to the planet. On striking the rings, the electrons charge the dust, causing the levitation of the fine grains above the main ring plane. A simulation of the proposed formation process provides strong supporting evidence for the validity of the process, explaining the spokes' formation locations, morphologies, and subsequent development as observed in Voyager images. The process can be tested using Cassini observations; we outline how the model's validity can be gauged.

  4. Pattern formation in multiplex networks

    PubMed Central

    Kouvaris, Nikos E.; Hata, Shigefumi; Guilera, Albert Díaz-

    2015-01-01

    The advances in understanding complex networks have generated increasing interest in dynamical processes occurring on them. Pattern formation in activator-inhibitor systems has been studied in networks, revealing differences from the classical continuous media. Here we study pattern formation in a new framework, namely multiplex networks. These are systems where activator and inhibitor species occupy separate nodes in different layers. Species react across layers but diffuse only within their own layer of distinct network topology. This multiplicity generates heterogeneous patterns with significant differences from those observed in single-layer networks. Remarkably, diffusion-induced instability can occur even if the two species have the same mobility rates; condition which can never destabilize single-layer networks. The instability condition is revealed using perturbation theory and expressed by a combination of degrees in the different layers. Our theory demonstrates that the existence of such topology-driven instabilities is generic in multiplex networks, providing a new mechanism of pattern formation. PMID:26042606

  5. The MARC II Format: A Communications Format for Bibliographic Data.

    ERIC Educational Resources Information Center

    Avram, Henriette D.; And Others

    Utilizing both the experience gained from the Machine-Readable Cataloging (MARC) Pilot Project, which tested the feasibility of distributing Library of Congress cataloging in machine readable form to various users, and the results of extensive consultation with the library community and persons at the Library of Congress, a format for

  6. Formation Flying In Highly Elliptical Orbits Initializing the Formation

    NASA Technical Reports Server (NTRS)

    Mailhe, Laurie; Schiff, Conrad; Hughes, Steven

    2000-01-01

    In this paper several methods are examined for initializing formations in which all spacecraft start in a common elliptical orbit subsequent to separation from the launch vehicle. The tetrahedron formation used on missions such as the Magnetospheric Multiscale (MMS), Auroral Multiscale Midex (AMM), and Cluster is used as a test bed Such a formation provides full three degrees-of-freedom in the relative motion about the reference orbit and is germane to several missions. The type of maneuver strategy that can be employed depends on the specific initial conditions of each member of the formation. Single-impulse maneuvers based on a Gaussian variation-of-parameters (VOP) approach, while operationally simple and intuitively-based, work only in a limited sense for a special class of initial conditions. These 'tailored' initial conditions are characterized as having only a few of the Keplerian elements different from the reference orbit. Attempts to achieve more generic initial conditions exceed the capabilities of the single impulse VOP. For these cases, multiple-impulse implementations are always possible but are generally less intuitive than the single-impulse case. The four-impulse VOP formalism discussed by Schaub is examined but smaller delta-V costs are achieved in our test problem by optimizing a Lambert solution.

  7. Formation of the first stars

    NASA Astrophysics Data System (ADS)

    Bromm, Volker

    2013-11-01

    Understanding the formation of the first stars is one of the frontier topics in modern astrophysics and cosmology. Their emergence signalled the end of the cosmic dark ages, a few hundred million years after the Big Bang, leading to a fundamental transformation of the early Universe through the production of ionizing photons and the initial enrichment with heavy chemical elements. We here review the state of our knowledge, separating the well understood elements of our emerging picture from those where more work is required. Primordial star formation is unique in that its initial conditions can be directly inferred from the ? cold dark matter (?CDM) model of cosmological structure formation. Combined with gas cooling that is mediated via molecular hydrogen, one can robustly identify the regions of primordial star formation, the so-called minihalos, having total masses of 106 M? and collapsing at redshifts z ? 20-30. Within this framework, a number of studies have defined a preliminary standard model, with the main result that the first stars were predominantly massive. This model has recently been modified to include a ubiquitous mode of fragmentation in the protostellar disks, such that the typical outcome of primordial star formation may be the formation of a binary or small multiple stellar system. We will also discuss extensions to this standard picture due to the presence of dynamically significant magnetic fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We conclude by discussing possible strategies to empirically test our theoretical models. Foremost among them are predictions for the upcoming James Webb space telescope (JWST), to be launched 2018, and for stellar archaeology, which probes the abundance pattern in the oldest, most-metal poor stars in our cosmic neighborhood, thereby constraining the nucleosynthesis inside the first supernovae.

  8. Formation of the first stars.

    PubMed

    Bromm, Volker

    2013-11-01

    Understanding the formation of the first stars is one of the frontier topics in modern astrophysics and cosmology. Their emergence signalled the end of the cosmic dark ages, a few hundred million years after the Big Bang, leading to a fundamental transformation of the early Universe through the production of ionizing photons and the initial enrichment with heavy chemical elements. We here review the state of our knowledge, separating the well understood elements of our emerging picture from those where more work is required. Primordial star formation is unique in that its initial conditions can be directly inferred from the Λ cold dark matter (ΛCDM) model of cosmological structure formation. Combined with gas cooling that is mediated via molecular hydrogen, one can robustly identify the regions of primordial star formation, the so-called minihalos, having total masses of ~10(6) M⊙ and collapsing at redshifts z ≈ 20-30. Within this framework, a number of studies have defined a preliminary standard model, with the main result that the first stars were predominantly massive. This model has recently been modified to include a ubiquitous mode of fragmentation in the protostellar disks, such that the typical outcome of primordial star formation may be the formation of a binary or small multiple stellar system. We will also discuss extensions to this standard picture due to the presence of dynamically significant magnetic fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We conclude by discussing possible strategies to empirically test our theoretical models. Foremost among them are predictions for the upcoming James Webb space telescope (JWST), to be launched ~2018, and for 'stellar archaeology', which probes the abundance pattern in the oldest, most-metal poor stars in our cosmic neighborhood, thereby constraining the nucleosynthesis inside the first supernovae. PMID:24168986

  9. Cosmic Star-Formation History

    NASA Astrophysics Data System (ADS)

    Madau, Piero; Dickinson, Mark

    2014-08-01

    Over the past two decades, an avalanche of new data from multiwavelength imaging and spectroscopic surveys has revolutionized our view of galaxy formation and evolution. Here we review the range of complementary techniques and theoretical tools that allow astronomers to map the cosmic history of star formation, heavy element production, and reionization of the Universe from the cosmic dark ages to the present epoch. A consistent picture is emerging, whereby the star-formation rate density peaked approximately 3.5 Gyr after the Big Bang, at z?1.9, and declined exponentially at later times, with an e-folding timescale of 3.9 Gyr. Half of the stellar mass observed today was formed before a redshift z = 1.3. About 25% formed before the peak of the cosmic star-formation rate density, and another 25% formed after z = 0.7. Less than 1% of today's stars formed during the epoch of reionization. Under the assumption of a universal initial mass function, the global stellar mass density inferred at any epoch matches reasonably well the time integral of all the preceding star-formation activity. The comoving rates of star formation and central black hole accretion follow a similar rise and fall, offering evidence for coevolution of black holes and their host galaxies. The rise of the mean metallicity of the Universe to about 0.001 solar by z = 6, one Gyr after the Big Bang, appears to have been accompanied by the production of fewer than ten hydrogen Lyman-continuum photons per baryon, a rather tight budget for cosmological reionization.

  10. Optimal Reconfiguration of Tetrahedral Formations

    NASA Technical Reports Server (NTRS)

    Huntington, Geoffrey; Rao, Anil V.; Hughes, Steven P.

    2004-01-01

    The problem of minimum-fuel formation reconfiguration for the Magnetospheric Multi-Scale (MMS) mission is studied. This reconfiguration trajectory optimization problem can be posed as a nonlinear optimal control problem. In this research, this optimal control problem is solved using a spectral collocation method called the Gauss pseudospectral method. The objective of this research is to provide highly accurate minimum-fuel solutions to the MMS formation reconfiguration problem and to gain insight into the underlying structure of fuel-optimal trajectories.

  11. Core formation by giant impacts

    NASA Technical Reports Server (NTRS)

    Tonks, W. B.; Melosh, H. J.

    1992-01-01

    The present model for the timing and mechanisms of planetary core formation argues that once a planet reaches a certain minimum mass, the large impacts that are typical of late accretion can trigger core formation. This model circumvents the difficulties posed by the large-scale segregation of molten iron into diapirs, and the displacement of the cold, elastic interior of the planet by the iron. The analytical melting model used is based on the Hugoniot equations, the empirical relationship for the decline of particle velocity with distance, and the linear shock-particle velocity relationship.

  12. Star formation and extinct radioactivities

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.

    1984-01-01

    An assessment is made of the evidence for the existence of now-extinct radioactivities in primitive solar system material, giving attention to implications for the early stages of sun and solar system formation. The characteristics of possible disturbances in dense molecular clouds which can initiate the formation of cloud cores is discussed, with emphasis on these disturbances able to generate fresh radioactivities. A one-solar mass red giant star on the asymptotic giant branch appears to have been the best candidate to account for the short-lived extinct radioactivities in the early solar system.

  13. Pattern formation in the geosciences

    PubMed Central

    Goehring, Lucas

    2013-01-01

    Pattern formation is a natural property of nonlinear and non-equilibrium dynamical systems. Geophysical examples of such systems span practically all observable length scales, from rhythmic banding of chemical species within a single mineral crystal, to the morphology of cusps and spits along hundreds of kilometres of coastlines. This article briefly introduces the general principles of pattern formation and argues how they can be applied to open problems in the Earth sciences. Particular examples are then discussed, which summarize the contents of the rest of this Theme Issue. PMID:24191107

  14. Paleoenvironmental and paleoclimatic significance of freshwater bivalves in the Upper Jurassic Morrison Formation, Western Interior, USA

    NASA Astrophysics Data System (ADS)

    Good, Steven C.

    2004-05-01

    Freshwater unionid bivalves are spatially and temporally distributed throughout the Morrison depositional basin, and locally dominate the biomass of many aquatic depositional environments. Two bivalve assemblages are identified. Within-channel assemblages are death assemblages that have been transported and may represent mixed assemblages from multiple communities. These assemblages are predominately disarticulated, in current stable orientations, and composed of higher stream velocity ecophenotypes (medium size, lanceolate form, and very thick shells). The floodplain-pond assemblages are disturbed neighborhood assemblages in the mudstones inhabited during life. The bivalves are predominately articulated, variable in size, and composed of low stream velocity ecophenotypes (large maximum sizes, ovate shell shapes, and thinner shells). The glochidial parasitic larval stage of unionid bivalves provides an effective means of dispersing species throughout drainage basins. These larvae attach to fish and are carried through the fluvial drainage where the larvae detach and establish new bivalve communities. Preliminary paleobiogeographic analyses are drawn at the genus level because of the need to reevaluate bivalve species of the Morrison. Unio spp. and Vetulonaia spp. are widespread throughout the Morrison depositional basin, but Hadrodon spp. are restricted to the eastern portion of the Colorado Plateau during Salt Wash Member deposition, suggesting that Salt Wash drainage was isolated from other contemporaneous regions of the basin. Bivalves from five localities in the Morrison Formation were thin-sectioned for growth band analysis. Growth bands of modern unionid bivalves are produced when the valves are forced to close. Closure can produce annual growth bands in response to seasonal variation, such as temperature-induced hibernation, or precipitation-induced aestivation or turbidity. Pseudoannual growth bands form from non-cyclical events such as predation attacks or isolated storm turbidity. Vetulonaia sp. from the Tidwell Member, Green River, Utah, and from Tidwell-equivalent beds at Como Bluff, Wyoming, exhibits continuous growth with no annual banding, suggesting that seasonality of climate and discharge did not vary appreciable during the year. Hadrodon sp. from the Salt Wash Member in Colorado National Monument, Colorado, exhibits annual banding with subequal light and dark bands indicating seasonal cyclicity. Vetulonaia sp. from the Cleveland-Lloyd locality, Utah, exhibits complex banding that indicates a combination of annual and pseudoannual bands. This suggests seasonal cyclicity and intermittent periods of environmental stress (predation, storm-produced turbidity and/or volcanic ash falls). Specimens of Vetulonaia sp. from Dinosaur National Monument, Utah, are replaced by chert with faint ghosts of bands that are too poorly preserved for environmental interpretations. Preliminary growth band studies suggest a change from a uniform optimum habitat in the Tidwell Member to strongly developed annual growth banding in the Salt Wash Member, suggesting cyclic annual precipitation, and finally to irregular banding produced by a complex interaction of weakly developed annual growth bands and pseudoannual bands in the Brushy Basin Member.

  15. 77 FR 47131 - Notice of Sunshine Act Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-07

    ....C. (Calvert Cliffs Nuclear Power Plant, Unit 3), et al., Petition to Suspend Final Decisions on... public meetings in another format (e.g. braille, large print), please notify Bill Dosch, Chief, Work Life... From the Federal Register Online via the Government Publishing Office NUCLEAR...

  16. Star formation across galactic environments

    NASA Astrophysics Data System (ADS)

    Young, Jason

    I present here parallel investigations of star formation in typical and extreme galaxies. The typical galaxies are selected to be free of active galactic nuclei (AGN), while the extreme galaxies host quasars (the most luminous class of AGN). These two environments are each insightful in their own way; quasars are among the most violent objects in the universe, literally reshaping their host galaxies, while my sample of AGN-free star-forming galaxies ranges from systems larger than the Milky Way to small galaxies which are forming stars at unsustainably high rates. The current paradigm of galaxy formation and evolution suggests that extreme circumstances are key stepping stones in the assembly of galaxies like our Milky Way. To test this paradigm and fully explore its ramifications, this dual approach is needed. My sample of AGN-free galaxies is drawn from the KPNO International Spectroscopic Survey. This Halpha-selected, volume-limited survey was designed to detect star-forming galaxies without a bias toward continuum luminosity. This type of selection ensures that this sample is not biased toward galaxies that are large or nearby. My work studies the KISS galaxies in the mid- and far-infrared using photometry from the IRAC and MIPS instruments aboard the Spitzer Space Telescope. These infrared bands are particularly interesting for star formation studies because the ultraviolet light from young stars is reprocessed into thermal emission in the far-infrared (24mum MIPS) by dust and into vibrational transitions features in the mid-infrared (8.0mum IRAC) by polycyclic aromatic hydrocarbons (PAHs). The work I present here examines the efficiencies of PAH and thermal dust emission as tracers of star-formation rates over a wide range of galactic stellar masses. I find that the efficiency of PAH as a star-formation tracer varies with galactic stellar mass, while thermal dust has a highly variable efficiency that does not systematically depend on galactic stellar mass. Complementing this study of normal star-forming galaxies, my study of quasar host galaxies utilizes narrow- and medium-band images of eight Palomar-Green (PG) quasars from the WFPC2 and NICMOS instruments aboard the Hubble Space Telescope. Using images of a point-spread function (PSF) star in the same filters, I subtract the PSF of the quasar from each of the target images. The residual light images clearly show the host galaxies of the respective quasars. The narrow-band images were chosen to be centered on the Hbeta, [O II ], [O III], and Paalpha emission lines, allowing the use of line ratios and luminosities to create extinction and star formation maps. Additionally, I utilize the line-ratio maps to distinguish AGN-powered line emission from star formation powered line emission with line-diagnostic diagrams. I find star formation in each of the eight quasar host galaxies in my study. The bulk star-formation rates are lower than expected, suggesting that quasar host galaxies may be dynamically more advanced than previously believed. Seven of the eight quasar host galaxies in this study have higher-than-typical mass-specific star-formation rates. Additionally, I see evidence of shocked gas, supporting the hypotheses presented in earlier works that suggest that AGN activity quenches star formation in its host galaxy by disrupting its gas reservoir.

  17. Chevrons formation in laminar erosion

    NASA Astrophysics Data System (ADS)

    Devauchelle, Olivier; Josserand, Christophe; Lagree, Pierre-Yves; Zaleski, Stephane; Nguyen, Khanh-Dang; Malverti, Luce; Lajeunesse, Eric

    2007-11-01

    When eroded by laminar free-surface flows, granular substrates may generate a rich variety of natural patterns. Among them are dunes, similar to the ones observed by Charru and Hinch in a Couette cell (Charru F, Hinch EJ ; Ripple formation on a particle bed sheared by a viscous liquid. Part 1. Steady flow ; JOURNAL OF FLUID MECHANICS 550: 111-121 MAR 10 2006). Chevron-shaped instabilities as those found on the sea-shore, can also be observed, sometimes in competition against dunes formation. These were first pointed out by Daerr et al. when pulling a plate covered with granular material out of a bath of water (Daerr A, Lee P, Lanuza J, et al. ; Erosion patterns in a sediment layer ; PHYSICAL REVIEW E 67 (6): Art. No. 065201 Part 2 JUN 2003). Both instabilities can grow in laminar open-channel flows, an experimental set-up which is more easily controlled. The mechanisms leading to the formation of these patterns are investigated and compared. Whereas dunes formation requires vertical inertia effects, we show that chevrons may result from the non-linear evolution of bars instability, which may grow even in purely viscous flows.

  18. Formative Assessment in Dance Education

    ERIC Educational Resources Information Center

    Andrade, Heidi; Lui, Angela; Palma, Maria; Hefferen, Joanna

    2015-01-01

    Feedback is crucial to students' growth as dancers. When used within the framework of formative assessment, or assessment for learning, feedback results in actionable next steps that dancers can use to improve their performances. This article showcases the work of two dance specialists, one elementary and one middle school teacher, who have

  19. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying the data. They can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). ...

  20. Formation of myocardial zonal lesions.

    PubMed Central

    Ratliff, N. B.; Kopelman, R. I.; Goldner, R. D.; Cruz, P. T.; Hackel, D. B.

    1975-01-01

    Right ventricular papillary muscles from control cats and from cats subjected to hemorrhagic shock were studied by electron microscopy. Half of the muscles were fixed at the apex of their active length-tension curves following stimulation in a papillary muscle bath. The other half were also fixed under tension. The ultrastructure of each muscle was examined in detail. A series of stages in the formation of myocardial zonal lesions, ranging from minimal changes in the intercalated discs to severe lesions, were identified and interpreted as representing the sequential stages in the formation of zonal lesions. One of the earliest (least severe) changes in the formation of zonal lesions, the separations of actin filaments from the intercalated disc, may be critical to the subsequent development of cardiac failure in hypovolemic shock. Mitochondrial displacement was a late event in the formation of the lesions, occurring only after major alterations had taken place in the sarcomeres and intercalated discs. It was noted that the ultrastructure of mitochondria remained essentially normal, and that there was no cell swelling associated with zonal lesions. This serves as confirmatory evidence that myocardial zonal lesions are a unique form of myocyte injury, are potentially reversible, and are not caused by ischemia. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 Fig 6 Fig 7 Fig 8 Fig 9 Fig 10 PMID:1146964

  1. Cave Formations in Wind Cave

    USGS Multimedia Gallery

    Wind Cave is the first cave national park and currently, the 6th most extensive cave network in the world. It's most famous for its large concentration of a fairly rare cave formation known as boxwork. Boxwork is formed when dissolved calcium carbonate crystallized in cracks in surrounding rock. The...

  2. A standard audit trail format

    SciTech Connect

    Bishop, M.

    1995-02-01

    The central role of audit trails, or (more properly) logs, in security monitoring needs little description, for it is too well known for any to doubt it. Auditing, or the analysis of logs, is a central part of security not only in computer system security but also in analyzing financial and other non-technical systems. As part of this process, it is often necessary to reconcile logs from different sources. This speaks of a need for a standard logging format. A standard log format robust enough to meet the needs of heterogeneity, transportability across various network protocols, and flexibility sufficient to meet a variety of needs in very different environments must satisfy two basic properties: extensibility and portability. This report presents the author`s proposed format for a standard log record. In section 3, he shows how and where the translation should be done, and in section 4 he demonstrates how log records from several disparate systems would be put into this format. Section 5 concludes with some observations and suggestions for future work.

  3. Moon formation: Earth's titanium twin

    NASA Astrophysics Data System (ADS)

    Meier, Matthias M. M.

    2012-04-01

    A giant impact on the young proto-Earth is thought to explain the formation of the Moon. High-precision analysis of titanium isotopes in lunar rocks suggests that the Moon and Earth's mantle are more similar than existing models permit.

  4. Formative Assessment in Primary Science

    ERIC Educational Resources Information Center

    Loughland, Tony; Kilpatrick, Laetitia

    2015-01-01

    This action learning study in a year three classroom explored the implementation of five formative assessment principles to assist students' understandings of the scientific topic of liquids and solids. These principles were employed to give students a greater opportunity to express their understanding of the concepts. The study found that

  5. Formative Assessment: A Cybernetic Viewpoint

    ERIC Educational Resources Information Center

    Roos, Bertil; Hamilton, David

    2005-01-01

    This paper considers alternative assessment, feedback and cybernetics. For more than 30 years, debates about the bi-polarity of formative and summative assessment have served as surrogates for discussions about the workings of the mind, the social implications of assessment and, as important, the role of instruction in the advancement of learning.…

  6. Audiences for Contemporary Radio Formats.

    ERIC Educational Resources Information Center

    Lull, James T.; And Others

    A radio audience survey of 110 sample geographic clusters in the Santa Barbara, California, area served a twofold purpose: the construction of a demographic profile of audience types according to radio format choices, and the identification and analysis of various audience subgroups. A skip interval technique of these geographic clusters resulted

  7. Junction formation during desiccation cracking

    NASA Astrophysics Data System (ADS)

    Toga, K. B.; Alaca, B. Erdem

    2006-08-01

    In order to provide a sound physical basis for the understanding of the formation of desiccation crack networks, an experimental study is presented addressing junction formation. Focusing on junctions, basic features of the network determining the final pattern, provides an elemental approach and imparts conceptual clarity to the rather complicated problem of the evolution of crack patterns. Using coffee-water mixtures a clear distinction between junction formation during nucleation and propagation is achieved. It is shown that for the same drying suspension, one can switch from the well-known symmetric triple junctions that are unique to the nucleation phase to propagation junctions that are purely dictated by the variations of the stress state. In the latter case, one can even manipulate the path of a propagating crack in a deterministic fashion by changing the stress state within the suspension. Clear microscopic evidence is provided for the formation of propagation junctions, and material inhomogeneity is observed to be reflected by a broad distribution of angles, in stark contrast to shrinkage cracks in homogeneous solid films.

  8. Formative Assessment in Primary Science

    ERIC Educational Resources Information Center

    Loughland, Tony; Kilpatrick, Laetitia

    2015-01-01

    This action learning study in a year three classroom explored the implementation of five formative assessment principles to assist students' understandings of the scientific topic of liquids and solids. These principles were employed to give students a greater opportunity to express their understanding of the concepts. The study found that…

  9. Earth and Terrestrial Planet Formation

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.; Walsh, Kevin J.

    2015-09-01

    The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for the later stages of planet formation are presented. The classical models with the giant planets on fixed orbits are not consistent with the known history of the Solar System, fail to create a high Earth/Mars mass ratio, and, in many cases, are also internally inconsistent. The successful Grand Tack model creates a small Mars, a wet Earth, a realistic asteroid belt and the mass-orbit structure of the terrestrial planets. In the Grand Tack scenario, growth curves for Earth most closely match a Weibull model. The feeding zones, which determine the compositions of Earth and Venus follow a particular pattern determined by Jupiter, while the feeding zones of Mars and Theia, the last giant impactor on Earth, appear to randomly sample the terrestrial disk. The late accreted mass samples the disk nearly evenly.

  10. Videodisc Technology: Function and Formats.

    ERIC Educational Resources Information Center

    Sales, Gregory C.

    1989-01-01

    This first in a planned five-part series on the videodisc as an instructional tool provides a basic introduction to videodisc technology and highlights features that make it a desirable educational medium. Videodiscs are compared to slide projectors, films, and videotapes, and two basic videodisc formats are explained. (LRW)

  11. Biofilm formation in Streptococcus pneumoniae

    PubMed Central

    Domenech, Mirian; García, Ernesto; Moscoso, Miriam

    2012-01-01

    Summary Biofilm‐grown bacteria are refractory to antimicrobial agents and show an increased capacity to evade the host immune system. In recent years, studies have begun on biofilm formation by Streptococcus pneumoniae, an important human pathogen, using a variety of in vitro model systems. The bacterial cells in these biofilms are held together by an extracellular matrix composed of DNA, proteins and, possibly, polysaccharide(s). Although neither the precise nature of these proteins nor the composition of the putative polysaccharide(s) is clear, it is known that choline‐binding proteins are required for successful biofilm formation. Further, many genes appear to be involved, although the role of each appears to vary when biofilms are produced in batch or continuous culture. Prophylactic and therapeutic measures need to be developed to fight S. pneumoniae biofilm formation. However, much care needs to be taken when choosing strains for such studies because different S. pneumoniae isolates can show remarkable genomic differences. Multispecies and in vivo biofilm models must also be developed to provide a more complete understanding of biofilm formation and maintenance. PMID:21906265

  12. Amyloid Beta Mediates Memory Formation

    ERIC Educational Resources Information Center

    Garcia-Osta, Ana; Alberini, Cristina M.

    2009-01-01

    The amyloid precursor protein (APP) undergoes sequential cleavages to generate various polypeptides, including the amyloid [beta] (1-42) peptide (A[beta][1-42]), which is believed to play a major role in amyloid plaque formation in Alzheimer's disease (AD). Here we provide evidence that, in contrast with its pathological role when accumulated,

  13. The EPRDATA Format: A Dialogue

    SciTech Connect

    Hughes, III, Henry Grady

    2015-08-18

    Recently the Los Alamos Nuclear Data Team has communicated certain issues of concern in relation to the new electron/photon/relaxation ACE data format as released in the eprdata12 library. In this document those issues are parsed, analyzed, and answered.

  14. Mantle dynamics following supercontinent formation

    NASA Astrophysics Data System (ADS)

    Heron, Philip J.

    This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are explored in over 600 2D and over 20 3D numerical simulations to better understand how modelling method affects conclusions on mantle convection studies. The results from this thesis show that the failure to model tectonic plates, a high vigour of convection, and a (pseudo) temperature-dependent viscosity would distort the role of mantle plumes, continent insulation, and subduction in the thermal evolution of mantle dynamics.

  15. Inside-out planet formation

    SciTech Connect

    Chatterjee, Sourav; Tan, Jonathan C. E-mail: jt@astro.ufl.edu

    2014-01-01

    The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M {sub ⊕} planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

  16. Star Formation in Satellite Galaxies

    NASA Astrophysics Data System (ADS)

    Gutirrez, C. M.; Alonso, M. S.; Funes, , J. G.; Ribeiro, M. B.

    2006-08-01

    We present narrowband observations of the H? emission in a sample of 31 satellites orbiting isolated giant spiral galaxies. The sample studied spans the range -19 magformation rates are 0.68 and 3.66 Msolar yr-1, respectively. Maps of the spatial distribution of ionized gas are presented. The star-forming regions show a rich structure in which frequently discrete complexes are imposed over more diffuse structures. In general, the current star formation rates are smaller than the mean values in the past, obtained from the stellar content; this probably indicates a declining rate with time in the generation of new stars. However, the reserve of gas is enough to continue fueling the current levels of star formation activity for at least another Hubble time. Four of the objects (NGC 2718b, NGC 4541e, and NGC 5965a1 and NGC 5965a2) with higher current star formation rates show clear signs of interaction with close companions of comparable brightness at projected distances of 25, 20, and 2 kpc, respectively. The only two galaxies in our sample that do not show star formation activity are members of these interacting systems, and it is unclear if this is a consequence of intrinsic properties (both are early Hubble types) or if it is related to possible disruption of the external parts due to the interaction. In the case of the pair NGC 2718a-2718b there are indications of gas transport between the galaxies. Based on observations with the Vatican Advanced Technology Telescope: the Alice P. Lennon Telescope and the Thomas J. Bannan Astrophysics Facility.

  17. Scale formation during alkaline flooding

    SciTech Connect

    Krumrine, P.H.; Brock, G.F.; Mayer, E.H.

    1984-04-01

    Alkaline chemicals in enhanced recovery operations have been and are being used: 1) as preflush agents, 2) with polymers and surfactants, and 3) as a principal recovery agent. In these chemical flooding techniques the reactions of multivalent hardness ions with alkalis to form precipitates are of particular concern. These reactions can be prevented at the injection wells through adequate preflushing and/or the use of good quality softened water; filtration can be used to remove any precipitates. These practices minimize the precipitation and subsequent damage to the well equipment and to the formation around the injectors, and reduce the chance for injectivity impairment. In the formation a host of reactions which significantly alter the injected slug occur including: dissolution, mixing, neutralization, and ion exchange. These may lead to fluid diversion as precipitates form to block high flow channels. At the producing wells, however, precipitation and deposition phenomena are undesirable since scales can form to restrict production and foul well equipment. With the higher concentrations of alkali being used in the field, the development of well scaling has become noticeable and difficult to control using previously accepted practices. This paper describes the progress and experience gained at the Long Beach Unit, Wilmington, CA alkaline pilot dealing with scales formed in producing wells. These scales have been made up variously of calcium carbonate, magnesium silicate, and amorphous silica. In particular, the reservoir characteristics and chemical conditions leading to the scale formation are discussed in detail showing what, how, and why the scale forms. For the Wilmington alkaline pilot, the mixing during production of very hard waters from one subzone with moderately alkaline water from other subzones, and the dissolution of formation solids has led to scale formation in producers closest to the alkaline injection.

  18. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew R.; Piro, Anthony; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. Using the observed BH mass distribution from Galactic X-ray binaries, we investigate the probability that a star will make a BH as a function of its ZAMS mass. Although the shape of the black hole formation probability function is poorly constrained by current measurements, we believe that this framework is an important new step toward better understanding BH formation. We also consider some of the implications of this probability distribution, from its impact on the chemical enrichment from massive stars, to its connection with the structure of the core at the time of collapse, to the birth kicks that black holes receive. A probabilistic description of BH formation will be a useful input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  19. Inside-Out Planet Formation

    NASA Astrophysics Data System (ADS)

    Tan, Jonathan Charles; Chatterjee, Sourav; Hu, Xiao; Zhu, Zhaohuan; Mohanty, Subhanjoy

    2015-08-01

    The Kepler-discovered systems with tightly-packed inner planets (STIPs), typically with several planets of Earth to super-Earth masses on well-aligned, sub-AU orbits may host the most common type of planets in the Galaxy. They pose a great challenge for planet formation theories, which fall into two broad classes: (1) formation further out followed by migration; (2) formation in situ from a disk of gas and planetesimals. I review the pros and cons of these classes, before focusing on a new theory of sequential in situ formation from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (~cm-m size) "pebbles," drifting inward via gas drag. Pebbles first collect at the pressure trap associated with the transition from a magnetorotational instability (MRI)-inactive ("dead zone") region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an Earth to super-Earth-mass planet directly or induces gradual planet formation via core accretion. The planet continues to accrete until it becomes massive enough to isolate itself from the accretion flow via gap opening. The process repeats with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. I discuss the theory’s predictions for planetary masses, relative mass scalings with orbital radius, and minimum orbital separations, and their comparison with observed systems. Finally I speculate about potential causes of diversity of planetary system architectures, i.e., STIPs versus Solar System analogs.

  20. Peripheral Leptin Regulates Bone Formation

    PubMed Central

    Turner, Russell T.; Kalra, Satya P.; Wong, Carmen P.; Philbrick, Kenneth A.; Lindenmaier, Laurence B.; Boghossian, Stephane; Iwaniec, Urszula T.

    2012-01-01

    Substantial evidence does not support the prevailing view that leptin, acting through a hypothalamic relay, decreases bone accrual by inhibiting bone formation. To clarify the mechanisms underlying regulation of bone architecture by leptin, we evaluated bone growth and turnover in wild type (WT) mice, leptin receptor-deficient db/db mice, leptin-deficient ob/ob mice and ob/ob mice treated with leptin. We also performed hypothalamic leptin gene therapy to determine the effect of elevated hypothalamic leptin levels on osteoblasts. Finally, to determine the effects of loss of peripheral leptin signaling on bone formation and energy metabolism, we used bone marrow (BM) from WT or db/db donor mice to reconstitute the hematopoietic and mesenchymal stem cell compartments in lethally irradiated WT recipient mice. Decreases in bone growth, osteoblast-lined bone perimeter and bone formation rate were observed in ob/ob mice and greatly increased in ob/ob mice following subcutaneous administration of leptin. Similarly, hypothalamic leptin gene therapy increased osteoblast-lined bone perimeter in ob/ob mice. In spite of normal osteoclast-lined bone perimeter, db/db mice exhibited a mild but generalized osteopetrotic-like (calcified cartilage encased by bone) skeletal phenotype and greatly reduced serum markers of bone turnover. Tracking studies and histology revealed quantitative replacement of BM cells following BM transplantation. WT mice engrafted with db/db BM did not differ in energy homeostasis from untreated WT mice or WT mice engrafted with WT BM. Bone formation in WT mice engrafted with WT BM did not differ from WT mice, whereas bone formation in WT mice engrafted with db/db cells did not differ from the low rates observed in untreated db/db mice. In summary, our results indicate that leptin, acting primarily through peripheral pathways, increases osteoblast number and activity. PMID:22887758

  1. Dioxin formation from waste incineration.

    PubMed

    Shibamoto, Takayuki; Yasuhara, Akio; Katami, Takeo

    2007-01-01

    There has been great concern about dioxins-polychlorinated dibenzo dioxins (PCDDs), polychlorinated dibenzo furans (PCDFs), and polychlorinated biphenyls (PCBs)-causing contamination in the environment because the adverse effects of these chemicals on human health have been known for many years. Possible dioxin-contamination has received much attention recently not only by environmental scientists but also by the public, because dioxins are known to be formed during the combustion of industrial and domestic wastes and to escape into the environment via exhaust gases from incinerators. Consequently, there is a pressing need to investigate the formation mechanisms or reaction pathways of these chlorinated chemicals to be able to devise ways to reduce their environmental contamination. A well-controlled small-scale incinerator was used for the experiments in the core references of this review. These articles report the investigation of dioxin formation from the combustion of various waste-simulated samples, including different kinds of paper, various kinds of wood, fallen leaves, food samples, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene tetraphthalate (PET), and various kinds of plastic products. These samples were also incinerated with inorganic chlorides (NaCl, KCl, CuCI2, MgCl2, MnCl2, FeCl2, CoCl2, fly ash, and seawater) or organic chlorides (PVC, chlordane, and pentachlorophenol) to investigate the role of chlorine content and/or the presence of different metals in dioxin formation. Some samples, such as newspapers, were burned after they were impregnated with NaCl or PVC, as well as being cocombusted with chlorides. The roles of incineration conditions, including chamber temperatures, O2 concentrations, and CO concentrations, in dioxin formation were also investigated. Dioxins (PCDDs, PCDFs, and coplanar-PCBs) formed in the exhaust gases from a controlled small-scale incinerator, where experimental waste samples were burned, were analyzed by gas chromatography/mass spectrometry. Formation of total PCDFs was much higher than that of PCDDs in all samples. The total PCDFs comprised 70%-90% of the total dioxin formed. The amount of total PCDFs formed ranged from 0.78 ng/g (newspaper) to 8,490ng/g (PVC burned in high CO concentration). The amount of total PCDDs formed ranged from 0.02ng/g (newspaper) to 430ng/g (PVC). Coplanar PCBs were found at the lowest level of the dioxins formed. Their formation levels ranged from 0ng/g (newspaper) to 77.6ng/g (PVC). It is obvious that the samples with either inorganic or organic chlorides produced much more dioxins than the sample without chlorides when incinerated under similar conditions. It is not clear how inorganic and organic chloride contribute differently to dioxin formation. Among the metals examined, copper seems to have higher activity toward dioxin formation than other metals. It acted not only as a catalyst but also as a transmitter of heterogeneous chlorine. The toxicity equivalence quantity (TEQ) values generally correlated with the amount of chlorine content in the samples and the amount of dioxin formed in exhaust gases from an incinerator. When the same sample was incinerated at different temperatures, however, the sample burned at low temperature yielded a higher TEQ value than did the sample burned at high temperature. The samples that did not contain chlorine or were not combusted with chlorides exhibited low TEQ values. In contrast, samples with high chlorine content, such as PVC (51.3%), gave high TEQ values. Combustion temperatures may play an important role in dioxin formation in exhaust gases from the incineration of waste materials. However, no significant relationship between dioxin formation and chamber temperatures was reported in the core articles. However, It is obvious that dioxin formation occurred at temperatures above 450'C and was reduced significantly at temperatures above 850 degrees C. The reaction occurring in an incinerator is extremely complex, and there are many factors in addition to combustion temperature influencing dioxin formation. Even though it is possible to hypothesize reasonable formation mechanisms of dioxins produced in exhaust gases according to the results obtained from experiments in classical chemistry, the reactions involved in an incinerator are extremely complex and heterogeneous. More detailed investigation of the many individual factors influencing dioxin formation is needed to find ways to reduce their formation in individual and municipal incinerators. PMID:17432330

  2. What Is Formation? A Conceptual Discussion

    ERIC Educational Resources Information Center

    Sutphen, Molly; de Lange, Thomas

    2015-01-01

    This paper addresses the principles and connotations of the term "formation." In our discussion of formation, we draw on different disciplines in order to widen and deepen our understanding of the concept of formation. We also mirror the formation concept against comparable terms and draw on studies in which it has been applied in

  3. Method of fracturing a geological formation

    DOEpatents

    Johnson, James O.

    1990-01-01

    An improved method of fracturing a geological formation surrounding a well bore is disclosed. A relatively small explosive charge is emplaced in a well bore and the bore is subsequently hydraulically pressurized to a pressure less than the formation breakdown pressure and preferably greater than the fracture propagation pressure of the formation. The charge is denoted while the bore is so pressurized, resulting in the formation of multiple fractures in the surrounding formation with little or no accompanying formation damage. Subsequent hydraulic pressurization can be used to propagate and extend the fractures in a conventional manner. The method is useful for stimulating production of oil, gas and possibly water from suitable geologic formations.

  4. ASDF: A new data format for astronomy

    NASA Astrophysics Data System (ADS)

    Greenfield, P.; Droettboom, M.; Bray, E.

    2015-09-01

    We present the case for developing a successor format for the immensely successful FITS format. We first review existing alternative formats and discuss why we do not believe they provide an adequate solution. The proposed format is called the Advanced Scientific Data Format (ASDF) and is based on an existing text format, YAML, that we believe removes most of the current problems with the FITS format. An overview of the capabilities of the new format is given along with specific examples. This format has the advantage that it does not limit the size of attribute names (akin to FITS keyword names) nor place restrictions on the size or type of values attributes have. Hierarchical relationships are explicit in the syntax and require no special conventions. Finally, it is capable of storing binary data within the file in its binary form. At its basic level, the format proposed has much greater applicability than for just astronomical data.

  5. Treating tar sands formations with dolomite

    SciTech Connect

    Vinegar, Harold J.; Karanikas, John Michael

    2010-06-08

    Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

  6. Formation of quasiparallel Alfven solitons

    NASA Technical Reports Server (NTRS)

    Hamilton, R. L.; Kennel, C. F.; Mjolhus, E.

    1992-01-01

    The formation of quasi-parallel Alfven solitons is investigated through the inverse scattering transformation (IST) for the derivative nonlinear Schroedinger (DNLS) equation. The DNLS has a rich complement of soliton solutions consisting of a two-parameter soliton family and a one-parameter bright/dark soliton family. In this paper, the physical roles and origins of these soliton families are inferred through an analytic study of the scattering data generated by the IST for a set of initial profiles. The DNLS equation has as limiting forms the nonlinear Schroedinger (NLS), Korteweg-de-Vries (KdV) and modified Korteweg-de-Vries (MKdV) equations. Each of these limits is briefly reviewed in the physical context of quasi-parallel Alfven waves. The existence of these limiting forms serves as a natural framework for discussing the formation of Alfven solitons.

  7. Scale formation during alkaline flooding

    SciTech Connect

    Krumrine, P.H.; Brock, G.F.; Mayer, E.M.

    1984-04-01

    Alkaline chemicals in enhanced recovery operations have been and are being used: 1) as preflush agents, 2) with polymers and surfactants, and 3) as a principal recovery agent. In these chemical flooding techniques the reactions of multivalent hardness ions with alkalis to form precipitates are of particular concern. These reactions can be prevented at the injection wells through adequate preflushing and/or the use of good quality softened water; filtration can be used to remove any precipitates. These practices minimize the precipitation and subsequent damage to the well equipment and to the formation around the injectors, and reduce the chance for injectivity impairment. In the formation a host of reactions which significantly alter the injected slug occur including: dissolution, mixing, neutralization, and ion exchange. These may lead to fluid diversion as precipitates form to block high flow channels.

  8. Molecule Formation on Interstellar Grains

    NASA Astrophysics Data System (ADS)

    Vidali, G.

    2011-05-01

    The first experiments that were expressively designed to be applicable to hydrogen formation reactions in the ISM measured the efficiency of formation of molecular hydrogen on a polycrystalline olivine (Pirronello et al. (1997a)). It soon turned out that more was needed, and research began on the mechanism of reaction, on the in uence of the surface morphology, and on the excitation of the just- ormed molecule. In this review, I summarize what we learned from these and other experiments, and where more work is needed: in the elementary steps of reaction, in the bridging of the laboratory-ISM gap (large ux/large surface - small ux/small grain) using simulations, and in using realistic samples of dust grains. Understanding what experiments can and cannot deliver will help in designing and targeting observations, and vice-versa.

  9. Shock formation in Lovelock theories

    NASA Astrophysics Data System (ADS)

    Reall, Harvey S.; Tanahashi, Norihiro; Way, Benson

    2015-02-01

    We argue that Lovelock theories of gravity suffer from shock formation, unlike general relativity. We consider the propagation of (i) a discontinuity in curvature, and (ii) weak, high frequency, gravitational waves. Such disturbances propagate along characteristic hypersurfaces of a "background" spacetime and their amplitude is governed by a transport equation. In general relativity, the transport equation is linear. In Lovelock theories, it is nonlinear and its solutions can blow up, corresponding to the formation of a shock. We show that this effect is absent in some simple cases, e.g. a flat background spacetime, and demonstrate its presence for a plane wave background. We comment on weak cosmic censorship, the evolution of shocks, and the nonlinear stability of Minkowski spacetime, in Lovelock theories.

  10. Laser beam pulse formatting method

    DOEpatents

    Daly, T.P.; Moses, E.I.; Patterson, R.W.; Sawicki, R.H.

    1994-08-09

    A method for formatting a laser beam pulse using one or more delay loops is disclosed. The delay loops have a partially reflective beam splitter and a plurality of highly reflective mirrors arranged such that the laser beam pulse enters into the delay loop through the beam splitter and circulates therein along a delay loop length defined by the mirrors. As the laser beam pulse circulates within the delay loop a portion thereof is emitted upon each completed circuit when the laser beam pulse strikes the beam splitter. The laser beam pulse is thereby formatted into a plurality of sub-pulses. The delay loops are used in combination to produce complex waveforms by combining the sub-pulses using additive waveform synthesis. 8 figs.

  11. Rapid gas hydrate formation process

    DOEpatents

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  12. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P. (Livermore, CA); Moses, Edward I. (Livermore, CA); Patterson, Ralph W. (Livermore, CA); Sawicki, Richard H. (Danville, CA)

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  13. Magnetic Diffusion in Star Formation

    NASA Astrophysics Data System (ADS)

    Basu, Shantanu; Dapp, Wolf B.

    2011-04-01

    Magnetic diffusion plays a vital role in star formation. We trace its influence from interstellar cloud scales down to star-disk scales. On both scales, we find that magnetic diffusion can be significantly enhanced by the buildup of strong gradients in magnetic field structure. Large scale nonlinear flows can create compressed cloud layers within which ambipolar diffusion occurs rapidly. However, in the flux-freezing limit that may be applicable to photoionized molecular cloud envelopes, supersonic motions can persist for long times if driven by an externally generated magnetic field that corresponds to a subcritical mass-to-flux ratio. In the case of protostellar accretion, rapid magnetic diffusion (through Ohmic dissipation with additional support from ambipolar diffusion) near the protostar causes dramatic magnetic flux loss. By doing so, it also allows the formation of a centrifugal disk, thereby avoiding the magnetic braking catastrophe.

  14. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  15. THE BLACK HOLE FORMATION PROBABILITY

    SciTech Connect

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub ZAMS}) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P {sub BH}(M {sub ZAMS}) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  16. Cycling Behavior and Memory Formation

    PubMed Central

    Gerstner, Jason R.; Lyons, Lisa C.; Wright, Kenneth P.; Loh, Dawn H.; Rawashdeh, Oliver; Eckel-Mahan, Kristin L.; Roman, Gregg W.

    2014-01-01

    Circadian research has spent considerable effort in the determining clock output pathways, including identifying both physiological and behavioral processes that demonstrate significant time-of-day variation. Memory formation and consolidation represent notable processes shaped by endogenous circadian oscillators. To date, very few studies on memory mechanisms have considered potential confounding effects of time-of-day and the organisms innate activity cycles (e.g., nocturnal, diurnal, or crepuscular). The following studies highlight recent work describing this interactive role of circadian rhythms and memory formation, and were presented at a minisymposium at the 2009 annual meeting of the Society for Neuroscience. The studies illustrate these time-of-day observations in a variety of behavioral paradigms and model organisms, including olfactory avoidance conditioning in Drosophila, long-term sensitization in Aplysia, active-avoidance conditioning in Zebrafish, and classical fear conditioning in rodents, suggesting that the circadian influence on memory behavior is highly conserved across species. Evidence also exists for a conserved mechanistic relationship between specific cycling molecules and memory formation, and the extent to which proper circadian cycling of these molecules is necessary for optimal cognitive performance. Studies describe the involvement of the core clock gene period, as well as vasoactive intestinal peptide, melatonin, and the cAMP/MAPK (cAMP/mitogen-activated protein kinase) cascade. Finally, studies in humans describe evidence for alterations in cognitive performance based on an interaction between sleepwake homeostasis and the internal circadian clock. Conservation of a functional relationship between circadian rhythms with learning and memory formation across species provides a critical framework for future analysis of molecular mechanisms underlying complex behavior. PMID:19828795

  17. Pattern formation through gravitational instability.

    NASA Astrophysics Data System (ADS)

    Rica, S.

    1995-05-01

    As a consequence of gravitational instability, a spherical nebula creates a well defined pattern of matter. It follows that the largest concentrations of matter - where the planets were probably created - occur at well defined distances following a geometrical progression: the Titius-Bode law for the Solar System. The universality (in the form) of this law is verified for different planetary systems such as: Jupiter, Saturn and Uranus. It is also shown that turbulent vortices can be responsible for the formation of planets.

  18. Hydrogen Sulfide Inhibits Amyloid Formation

    PubMed Central

    2015-01-01

    Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and vascular dementia. The amount of hydrogen sulfide (H2S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H2S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of β-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H2S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550–500 cm–1 spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm–1 band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H2S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils. PMID:25545790

  19. Formation mechanism for interstellar molecules

    NASA Technical Reports Server (NTRS)

    Harteck, P.; Beaudoin, A.; Reeves, R.

    1973-01-01

    The major ions in the region of the interstellar clouds include H(+) and H2(+). The ions may be formed by photo ionization, cosmic rays, or other processes. The chemistry of H2(+) is considered and reactions involving carbon atoms are described. The formation of nitrogen-containing molecules may occur mainly on interstellar grains. Reactions involving negative ions may also contribute to the production of certain species.

  20. Method for fracturing subterranean formations

    SciTech Connect

    Almond, S. W.; Conway, M. W.

    1985-11-19

    The present invention relates to a thermally stable crosslinked gel fracturing fluid for use in the treatment of subterranean formations penetrated by a well bore. The fracturing fluid comprises an aqueous liquid, a gelling agent comprising a selected modified cellulose ether, a crosslinking agent and any additional additives that may be present. The fracturing fluid is thermally stable under shear at temperatures in excess of about 200/sup 0/ F.

  1. Theory of Planetary System Formation

    NASA Technical Reports Server (NTRS)

    Cassen, Patrick

    1996-01-01

    Observations and theoretical considerations support the idea that the Solar System formed by the collapse of tenuous interstellar matter to a disk of gas and dust (the primitive solar nebula), from which the Sun and other components separated under the action of dissipative forces and by the coagulation of solid material. Thus, planets are understood to be contemporaneous byproducts of star formation. Because the circumstellar disks of new stars are easier to observe than mature planetary systems, the possibility arises that the nature and variety of planets might be studied from observations of the conditions of their birth. A useful theory of planetary system formation would therefore relate the properties of circumstellar disks both to the initial conditions of star formation and to the consequent properties of planets to those of the disk. Although the broad outlines of such a theory are in place, many aspects are either untested, controversial, or otherwise unresolved; even the degree to which such a comprehensive theory is possible remains unknown.

  2. Formation stability after hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Papanastasiou, Panos

    1999-12-01

    This paper investigates stress changes resulting from fracturing in a weak formation and estimates the reduced risk of formation failure. The analysis is based on fracture propagation and closure of a plane strain elasto-plastic fracture. It is shown that during fracture propagation the area near the fracture tip undergoes plastic deformation, with the result that the in situ stresses there are significantly reduced from the original compressive state. The stress relief is driven by the reduction of the minimum in situ stress and the consistency condition which requires the stress state to remain on the yield or failure envelope. After fracture closure, due to permanent deformation the stress state does not return to its original state, as in the case of elastic material. The risk of formation failure, which is quantified with the introduction of a yield factor, is significantly reduced after fracturing and closure. The residual width from plastic deformation results in a non-uniform closure stress on proppant with higher values near the tip and lower value near the wellbore which is detrimental to the stability of proppant. The closure stress becomes more uniform with increasing fracture length.

  3. Formation of Outer Planets: Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack

    2003-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets is presented. The most detailed models are based upon observation of our own Solar System and of young stars and their environments. Terrestrial planets are believe to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk disspates. The primary questions regarding the core instability model is whether planets with small cores can accrete gaseous enveloples within the lifetimes of gaseous protoplanetary disks. The main alternative giant planet formation model is the disk instability model, in which gaseous planets form directly via gravitational instabilities within protoplanetary disks. Formation of giant planets via gas instability has never been demonstrated for realistic disk conditions. Moreover, this model has difficulty explaining the supersolar abundances of heavy elements in Jupiter and Saturn, and it does not explain the orgin of planets like Uranus and Neptune.

  4. Contrail formation in aircraft wakes

    NASA Astrophysics Data System (ADS)

    Paoli, Roberto; Hlie, Jerome; Poinsot, Thierry

    2004-03-01

    The process of the formation and early evolution of a condensation trail (contrail) in the near field of an aircraft wake was numerically studied by means of a mixed Eulerian/Lagrangian two-phase flow approach. Large-eddy simulations were used for the carrier phase, while, for the dispersed phase, a Lagrangian particle tracking method was used, coupled with a microphysics model to account for ice nucleation. The basic configuration was an exhaust engine jet loaded with soot particles and water vapour and interacting with a wing-tip trailing vortex. The thermodynamic conditions for contrail formation were identified by tracking the spatial distribution of supersaturation around particles. A strong mass coupling between the two phases was demonstrated by the simulations: the condensation of water vapour over soot particles, induced by exhaust dispersion into cold ambient air, leads to the formation of ice crystals whose size grows until thermodynamic equilibrium between the two phases is reached. Finally, local vapour depletion causes significant deviation from the classical mixing line theory and is also responsible for polydispersion of particle radii.

  5. Supernova Feedback in Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Dubois, Y.; Teyssier, R.

    2008-06-01

    The hierarchical model of galaxy formation is known to suffer from the ``over-cooling'' problem: the high efficiency of radiative cooling results in too much baryonic matter in a condensed phase (namely, cold gas or stars) when compared to observations. A solution proposed by many authors (see Springel & Hernquist 2003; Fujita et al. 2004; Rasera & Teyssier 2005) is feedback due to supernova (SN) driven winds or active galactic nuclei. Modeling SN feedback by direct injection of thermal energy usually turns out to be inefficient in galaxy-scale simulations, due to the quasi-instantaneous radiation of the SN energy. To avoid this effect, we have developed a new method to incorporate SN feedback in cosmological simulations: using temporary test particles, we reproduce explicitly a local Sedov blast wave solution in the gas distribution. We have performed several self-consistent runs of isolated Navarro, Frenk, & White (1996, hereafter NFW) halos with radiative cooling, star formation, SN feedback and metal enrichment using the adaptive mesh refinement code RAMSES (Teyssier 2002). We have explored the influence of SN feedback on the formation and the evolution of galaxies with different masses. We have studied the efficiency of the resulting galactic winds, as a function of the mass of the parent halo.

  6. A New Spoke Formation Model

    NASA Astrophysics Data System (ADS)

    Jones, Geraint H.; Krupp, N.; Krueger, H.; Roussos, E.; Ip, W.; Mitchell, D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Fraenz, M.; Dougherty, M. K.; Arridge, C. S.; McAndrews, H. J.

    2006-09-01

    We propose a new model for the formation of spokes in Saturn's rings. The model involves the electrostatic charging of sub-micron dust grains in the rings by magnetic field-aligned electron beams. Such beams have recently been observed by the MIMI instrument aboard Cassini at 3.1 Saturn radii, outside the main ring system. It is reasonable to expect the beams to also occur closer to the planet. We contend that on striking the rings, the electron beams dust-charging effects cause the levitation of the fine grains above the main ring plane, forming the spokes. Using a semi-quantitative model, we explain the spokes formation locations, their initial morphologies, and the subsequent development of their appearance as reported in studies based on Voyager observations. Controlling effects on the spokes locations are also proposed. We outline tests that can be carried out using Cassini datasets to gauge the validity of our proposed formation process. MIMI/LEMMS work at MPS is financed by the German Bundesministerium fr Bildung und Forschung, and by the Max Planck Gesellschaft.

  7. Bubble migration during hydrate formation

    NASA Astrophysics Data System (ADS)

    Shagapov, V. Sh.; Chiglintseva, A. S.; Rusinov, A. A.

    2015-03-01

    A model of the process of migration of methane bubbles in water under thermobaric conditions of hydrate formation is proposed. The peculiarities of the temperature field evolution, migration rate, and changes in the radius and volume fraction of gas hydrate bubbles are studied. It is shown that, with a constant mass flow of gas from the reservoir bottom, for all parameters of the surfacing gas hydrate disperse system, there is a quasistationary pattern in the form of a "step"-like wave. Depending on the relationship of the initial gas bubble density with the average gas density in the hydrate composition determined by the depth from which bubbles rise to the surface, the final radius of hydrate particles may be larger or smaller than the initial gas bubble radii. It is established that the speed at which gas hydrate inclusions rise to the surface decreases by several times due to an increase in their weight during hydrate formation. The influence of the depth of the water reservoir whose bottom is a gas flow source on the dynamics of hydrate formation is studied.

  8. Memory Formation Shaped by Astroglia

    PubMed Central

    Zorec, Robert; Horvat, Anemari; Vardjan, Nina; Verkhratsky, Alexei

    2015-01-01

    Astrocytes, the most heterogeneous glial cells in the central nervous system (CNS), execute a multitude of homeostatic functions and contribute to memory formation. Consolidation of synaptic and systemic memory is a prolonged process and hours are required to form long-term memory. In the past, neurons or their parts have been considered to be the exclusive cellular sites of these processes, however, it has now become evident that astrocytes provide an important and essential contribution to memory formation. Astrocytes participate in the morphological remodeling associated with synaptic plasticity, an energy-demanding process that requires mobilization of glycogen, which, in the CNS, is almost exclusively stored in astrocytes. Synaptic remodeling also involves bidirectional astroglial-neuronal communication supported by astroglial receptors and release of gliosignaling molecules. Astroglia exhibit cytoplasmic excitability that engages second messengers, such as Ca2+, for phasic, and cyclic adenosine monophosphate (cAMP), for tonic signal coordination with neuronal processes. The detection of signals by astrocytes and the release of gliosignaling molecules, in particular by vesicle-based mechanisms, occurs with a significant delay after stimulation, orders of magnitude longer than that present in stimulus–secretion coupling in neurons. These particular arrangements position astrocytes as integrators ideally tuned to support time-dependent memory formation. PMID:26635551

  9. Outlook: Testing Planet Formation Theories

    NASA Astrophysics Data System (ADS)

    Boss, A. P.

    The discovery of the first planetary companion to a solar-type star by Mayor and Queloz (1995) launched the extrasolar planetary systems era. Observational and theoretical progress in this area has been made at a breathtaking pace since 1995, as evidenced by this workshop. We now have a large and growing sample of extrasolar gas giant planets with which to test our theories of their formation and evolution. The two competing theories for the formation of gas giant planets, core accretion and disk instability, appear to have testable predictions: (i) Core accretion seems to require exceptionally long-lived disks, implying that gas giants should be somewhat rare, while disk instability can occur in even the shortest-lived disk, implying that gas giants should be abundant. The ongoing census of gas giants by the spectroscopic search programs will determine the frequency of gas giants on Jupiter-like orbits within the next decade. (ii) Core accretion takes millions of years to form gas giants, while disk instability forms gaseous protoplanets in thousands of years. Determining the epoch of gas giant planet formation by searching for astrometric wobbles indicative of gas giant companions around young stars with a range of ages ( 0.1 Myr to 10 Myr) should be possible with the Space Interferometry Mission (SIM). (iii) Core accretion would seem to be bolstered by a higher ratio of dust to gas, whereas disk instability occurs equally well for a range of dust opacities. Determining whether a high primordial metallicity is necessary for gas giant planet formation can be accomplished by spectroscopic and astrometric searches for gas giants around metal-poor stars. Eventually, ice giant planets will be detectable as well. If ice giants are found to be much more frequent that gas giants, this may imply that core accretion occurs, but usually fails to form a gas giant. Terrestrial planets will be detected through photometry by Kepler and Eddington, astrometry by SIM, and imaging by Terrestrial Planet Finder and Darwin. Ultimately these detections will clarify the process of Earth formation by collisional accumulation, the only contending theory.

  10. Formation of the hurricane eye

    NASA Astrophysics Data System (ADS)

    Vigh, Jonathan L.

    This dissertation consists of three distinct studies which investigate aspects of eye formation. The first study reviews eye phenomenon in a variety of vortices ranging from simple vortices to the menagerie of geophysical vortices, emphasizing similarities and differences to the eyes formed in hurricanes. The hurricane eye is found to be a paradoxical structure imposed by conservation of angular momentum and the boundaries of the vortex. A comprehensive definition for hurricane eye formation is proposed and various eye formation mechanisms are summarized. The next study presents a simple theoretical argument to isolate the conditions under which a tropical cyclone can rapidly develop a warm-core thermal structure and subsequently approach a steady state. The theoretical argument is based on the balanced vortex model and, in particular, on the associated transverse circulation equation and the geopotential tendency equation. The transverse circulation and the temperature tendency in a tropical vortex depend not only on the diabatic forcing, but also on the spatial distributions of the static stability, the baroclinity, and the inertial stability. The vortex response to diabatic heating depends critically on whether the heating occurs in the low inertial stability region outside the radius of maximum wind or in the high inertial stability region inside the radius of maximum wind. This result suggests that rapid intensification is favored for storms which have at least some of the eyewall convection inside the radius of maximum wind. The development of an eye partially removes diabatic heating from the high inertial stability region of the storm center, yet rapid intensification may continue if the eyewall heating continues to become more efficient. As the warm core matures and static stability increases over the inner core, conditions there become less favorable for deep upright convection and the storm tends to approach a steady state. The final study characterizes the kinematic and thermodynamic changes that occur before, during, and after the initial eye formations of a broad set of Atlantic tropical cyclones. To obtain the requisite structure and intensity parameters, a new data set has been synthesized from the Vortex Data Messages transmitted by routine aircraft reconnaissance from 1989--2008. Intensity ranges are determined for the times when the eye/eyewall structure first appears in aircraft radar and infrared satellite imagery. The mean intensity at which an eye is first observed in both aircraft or satellite imagery is found to be 58 kt, somewhat lower than reported in previous studies. Changes about the time of eye formation are examined for intensity, the radius of maximum winds, the minimum Rossby radius of deformation, eye temperature and dew point temperature depression. Storms are found to intensify most rapidly near the time of eye formation, especially when a persistent eye is observed in infrared satellite imagery. Many storms which are forming eyes are found to undergo a substantial and rapid contraction in the radius of maximum winds during the 24-h period before the eye is observed; once the eye is present, this contraction slows or ceases. Strong warming at lower levels (850 or 700 hPa) of the eye is not observed to correlate well with the time in which the eye is first observed. Finally, observations suggest that the dynamical heating efficiency of the resulting eyewall increases even as the physical scale of the efficient heating region decreases. This allows the storm to continue intensifying even though the total inner core diabatic heating may decrease. The answer to why some storms fail to form eyes may shed light on whether eye formation is a stochastic process involving constructive and destructive mesoscale interactions---or whether it is a manifold attractor of the system sometimes stymied by an unfavorable environment.

  11. Core formation in silicate bodies

    NASA Astrophysics Data System (ADS)

    Nimmo, F.; O'Brien, D. P.; Kleine, T.

    2008-12-01

    Differentiation of a body into a metallic core and silicate mantle occurs most efficiently if temperatures are high enough to allow at least the metal to melt [1], and is enhanced if matrix deformation occurs [2]. Elevated temperatures may occur due to either decay of short-lived radio-isotopes, or gravitational energy release during accretion [3]. For bodies smaller than the Moon, core formation happens primarily due to radioactive decay. The Hf-W isotopic system may be used to date core formation; cores in some iron meteorites and the eucrite parent body (probably Vesta) formed within 1 My and 1-4~My of solar system formation, respectively [4]. These formation times are early enough to ensure widespread melting and differentiation by 26Al decay. Incorporation of Fe60 into the core, together with rapid early mantle solidification and cooling, may have driven early dynamo activity on some bodies [5]. Iron meteorites are typically depleted in sulphur relative to chondrites, for unknown reasons [6]. This depletion contrasts with the apparently higher sulphur contents of cores in larger planetary bodies, such as Mars [7], and also has a significant effect on the timing of core solidification. For bodies of Moon-size and larger, gravitational energy released during accretion is probably the primary cause of core formation [3]. The final stages of accretion involve large, stochastic collisions [8] between objects which are already differentiated. During each collision, the metallic cores of the colliding objects merge on timescales of a few hours [9]. Each collision will reset the Hf-W isotopic signature of both mantle and core, depending on the degree to which the impactor core re-equilibrates with the mantle of the target [10]. The re-equilibration efficiency depends mainly on the degree to which the impactor emulsifies [11], which is very uncertain. Results from N-body simulations [8,12] suggest that significant degrees of re- equilibration are required [4,10]. Re-equilibration is also suggested by mantle siderophile abundances [13], though simple partitioning models do not capture the likely complex P,T evolution during successive giant impacts. The timescale of Martian core formation is currently uncertain (0-10 My) [14], though it is clear that Martian core formation ended before that of the Earth. [1] Stevenson, in Origin of the Earth, 1990. [2] Groebner and Kohlstedt, EPSL 2006. [3] Rubie et al., Treatise Geophys. 2007. [4] Kleine et al., GCA submitted. [5] Weiss et al., LPSC 39, 2008. [6] Keil and Wilson, EPSL 1993 [7] Wanke and Dreibus, PTRSL, 1984. [8] Agnor et al. Icarus 1999 [9] Canup and Asphaug, Nature 2001 [10] Nimmo and Agnor, EPSL 2006. [11] Rubie et al., EPSL 2003 [12] O'Brien et al, Icarus 2006 [13] Righter, AREPS 2003. [14] Nimmo and Kleine, Icarus 2007.

  12. Early preheating and galaxy formation

    NASA Astrophysics Data System (ADS)

    Benson, A. J.; Madau, Piero

    2003-09-01

    Winds from pregalactic starbursts and `miniquasars' may pollute the intergalactic medium (IGM) with metals and raise its temperature to a much higher adiabat than expected from photoionization, and so inhibit the formation of early galaxies by increasing the cosmological Jeans mass. We compute the thermal history of the IGM when it experiences a period of rapid, homogeneous `preheating' at high redshifts, and the impact of such a global feedback mechanism on the IGM ionization state and the subsequent galaxy formation and evolution. Measurements of the temperature of the Ly? forest at redshift z~ 3 constrain the redshift and energy of preheating, and rule out models that preheat too late or to too high a temperature, i.e. to TIGM>~ 106 K at z<~ 10. The IGM thermal history is used to estimate the effects of preheating on the formation of galaxies at later epochs, allowing us to predict galaxy luminosity functions in preheated universes. The results depend crucially on whether the baryonic smoothing scale in the IGM is computed globally, or in a local, density-dependent fashion (since the IGM temperature can become highly inhomogeneous in the post-preheating epoch). Using a globally averaged smoothing scale, we find that models with excessive preheating produce too few L* and fainter galaxies, and are therefore inconsistent with observational data. More moderate preheating scenarios, with TIGM>~ 105 K at z~ 10, are able to flatten the faint-end slope of the luminosity function, producing excellent agreement with observations, without the need for any local feedback mechanism within galaxies. A density-dependent smoothing scale requires more energetic preheating to achieve the same degree of suppression in the faint-end slope. All models, however, appear unable to explain the sharp cut-off in the luminosity function at bright magnitudes - a problem that is also common to more conventional local feedback prescriptions. Supernova-driven preheating scenarios tend to raise the mean metallicity of the universe well above the minimum levels observed in the Ly? clouds. The high energies associated with preheating cause a sharp drop in the abundance of neutral hydrogen in the IGM and are often sufficient to double ionize helium at high redshift, well before the `quasar epoch'. We find that ionizing photon escape fractions must be significantly higher than 10 per cent in order to explain the low inferred H I fraction at z~ 6, particularly when using a globally averaged smoothing scale. While early preheating causes strong suppression of dwarf galaxy formation, we show that it is not able to reproduce the observed abundance of satellite galaxies in the Local Group in detail. The detailed thermal history of the universe during the formative early stages around z= 10-15 remains one of the crucial missing links in galaxy-formation and evolution studies.

  13. Feedback During Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei; Tan, Jonathan C.; Zhang, Yichen

    2016-01-01

    We present models of photoionization of massive protostellar cores, and show the impact of this ionization feedback on the efficiency of star formation and its observational features. Based on the Core Accretion scenario, we construct the collapse model of rotating massive-protostellar cloud cores together with a protostellar evolutional calculation, including feedback effects from a MHD disk wind, photoionization and radiation pressure. First, the MHD wind creates a bipolar outflow whose opening angle increases over the timescale of mass accretion. The ionizing luminosity dramatically increases after the protostar reaches ~ 5 Msun due to Kelvin-Helmholz contraction, and the MHD wind is photoionized when the protostellar mass reaches ~ 10 - 20 Msun. As the ionizing and bolometric luminosities increase, the outflow opening angle becomes wider due to radiation pressure feedback. By this combination of feedback processes, the envelope is eroded and the mass infall rate is significantly reduced to that arriving only from the disk-shielded equatorial region. At a protostellar mass of ~ 50 - 100 Msun, depending on the initial core properties, the mass accretion is halted by disk photoevaporation. In this way, feedback significantly reduces the star formation efficiency when forming massive stars from massive cloud cores, which could produce a cutoff at the high-mass end of the initial mass function. Along this evolutionary calculation, we also compute the detailed structure of the photoionized regions using a ray-tracing radiative transfer code and evaluate their emission signatures. Their free-free continuum and recombination line emissions are consistent with the variety of observed radio sources associated with massive protostars, i.e., jets and ultra/hyper-compact HII regions. The comparison between our models and such observations enables us to better define the evolutionary sequence of massive star formation.

  14. Sequential star formation in Cassiopeia

    NASA Astrophysics Data System (ADS)

    Velasco, S.; García, M.; Negueruela, I.

    2013-05-01

    Massive stars (M ≥ 9 M_{⊙}) are usually formed in OB associations, consisting of one or more not very massive open clusters and a halo of scattered young stars. The study of these open clusters can provide clues about how stellar formation proceeds from the parent molecular clouds. We present first results on a project to understand sequential star formation mechanisms in OB associations. We have chosen associations Cas OB4, Cas OB5 and Cas OB7, close to the Cassiopeia constellation, at l = 110°-125°. Previous determinations of their distance provided very similar values for them all, and placed them on the Perseus Arm. This study aims at improved distance and age determinations using new spectroscopic observations and existing photometry. The goal is to investigate whether the clusters in Cas OB4, Cas OB5 and Cas OB7 are separate entities or can be enclosed in a global common OB association. If associated,we will check for evidence of induced star formation. We preselected about 100 stars from 12 clusters, based on photometric criteria. Long-slit spectra were taken with the Intermediate Dispersion Spectrograph at the Isaac Newton Telescope (2.5 m), located in La Palma's Observatorio del Roque de los Muchachos. We used the R632V grating, to achieve a spectral coverage between 3500 Å and 5500 Å and spectral resolution of 0.90 Å px^{-1}. The observed spectra have been used to determine the spectral type and luminosity class of the sample stars. The spectral classification yields the stellar properties (from calibrations), and will enable the reconstruction of the HR-diagram. We present in this poster newly discovered B-type stars in two selected clusters.

  15. Statistical physics and opinion formation

    NASA Astrophysics Data System (ADS)

    Shao, Jia

    Many complex systems can be described by networks in which the nodes are the elements of the system and the links characterize the interactions between the elements. There have been concerted efforts to understand the topological properties of model and real-life complex networks. We solve analytically the structure of shells in a randomly connected complex network. Further, we study an opinion formation model based on complex networks and show that the process of opinion formation can be mapped to a real-life physics process---invasion percolation. We define shell ? in a network as the set of nodes at distance ? with respect to a given node and define r? as the fraction of nodes outside shell ?. We derive analytically the degree distribution and average degree of the nodes residing outside shell ? as a function of r?. Further, we find that r? follows an iterative functional form r ? = ?(r?-1), where ? is expressed in terms of the generating function of the original degree distribution of the network. For real world networks the theoretical prediction of r? deviates from the empirical r?. We introduce a network correlation function c(r?) ? r ?/?(r?-1) to characterize the correlations in the networks. We find that the networks fall into two distinct classes: (i) a class of poorly-connected networks with c(r?) > 1; (ii) a class of well-connected networks with c(r ?) < 1. We also apply the concept of a percolation phase transition to the modeling of opinion formation in complex networks. We propose a "non-consensus" opinion model that allows for stable coexistence of two opinions. We find that the model displays phase transition behavior characterized by a large spanning cluster of nodes holding the same opinion appearing when the concentration of nodes holding the same opinion rises above a certain threshold. Our simulations support the hypothesis that the non-consensus opinion model appears to belong to the same universality class as invasion percolation.

  16. WOUND HEALING AND COLLAGEN FORMATION

    PubMed Central

    Ross, Russell; Benditt, Earl P.

    1961-01-01

    The regular sequence encountered in healing guinea pig skin wounds has been examined by methods of light and electron microscopy. Observations on cell populations, their fine structure, and fibril formation in the connective tissue have been made. Linear incisions in the skin of normal female guinea pigs weighing 300 to 350 grams were allowed to heal. The wounds were then excised, fixed with buffered 2 per cent osmium tetroxide, and postfixed in neutral buffered formalin, at 16 and 24 hours and at 3, 5, 9, and 14 days after wounding. They were then embedded in epoxy resin. In the inflammatory phase the exudate observed in the early wounds consists largely of polymorphonuclear neutrophilic leukocytes, macrophages, fibrin, and free extracellular organelles from the disrupted inflammatory cells. These organelles later appear in vacuoles in the cytoplasm of the macrophages. Fibroblasts first appear at 24 hours, and show extensive development and dilatation of the endoplasmic reticulum, which sometimes contains moderately dense flocculent material. In addition, these fibroblasts have enlarged mitochondria and condensations of filamentous material within the cytoplasm near the cell surface. Occasional myelin figures and moderately dense, 0.5 to 1.0 micron bodies are found within the cytoplasm of the early fibroblasts. Collagen fibrils are first seen at 3 days extracellularly near the cell surfaces. They appear at the later times in two populations of sizes. With increasing wound age the fibroblasts retain their morphology and the wounds decrease in cellularity concomitantly with the formation of increasing amounts of collagen. Several proposed mechanisms of collagen fibril formation are discussed in relation to the observed phenomena. The problem of correlating fibril diameter with the appearance of the periodic structure of collagen in relation to the minimal size fibril which would be anticipated to display this appearance is discussed. PMID:14494202

  17. Electrochemical formation of field emitters

    SciTech Connect

    Bernhardt, Anthony F.

    1999-01-01

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

  18. Zonal flow as pattern formation

    SciTech Connect

    Parker, Jeffrey B.; Krommes, John A.

    2013-10-15

    Zonal flows are well known to arise spontaneously out of turbulence. We show that for statistically averaged equations of the stochastically forced generalized Hasegawa-Mima model, steady-state zonal flows, and inhomogeneous turbulence fit into the framework of pattern formation. There are many implications. First, the wavelength of the zonal flows is not unique. Indeed, in an idealized, infinite system, any wavelength within a certain continuous band corresponds to a solution. Second, of these wavelengths, only those within a smaller subband are linearly stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets.

  19. Putative mechanisms of peroxybicarbonate formation

    NASA Astrophysics Data System (ADS)

    Maetzke, Alice; Knak Jensen, Svend J.; Csizmadia, Imre G.

    2007-11-01

    The mechanism for the formation of the oxidant peroxymonocarbonate from hydrogen peroxide and bicarbonate/carbon dioxide in aqueous solution is studied by electron structure- and statistical mechanics techniques. It is found that the reaction proceeds through a single transition state. The activation energy is 83.3 kJ/mol at the highest level of theory [CCSD(T)/aug-cc-pvdz//B3LYP/aug-cc-pvdz]. However, it is reduced by 17% when the counter ion ( viz.NH4+) is incorporated in the calculations.

  20. Dust formation by failed supernovae

    NASA Astrophysics Data System (ADS)

    Kochanek, C. S.

    2014-11-01

    We consider dust formation during the ejection of the hydrogen envelope of a red supergiant during a failed supernova (SN) creating a black hole. While the dense, slow moving ejecta are very efficient at forming dust, only the very last phases of the predicted visual transient will be obscured. The net grain production consists of Md 10- 2 M? of very large grains (10-1000 ?m). This means that failed SNe could be the source of the very large extrasolar dust grains possibly identified by Ulysses, Galileo and radar studies of meteoroid re-entry trails rather than their coming from an ejection process associated with protoplanetary or other discs.