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1

The physical conditions indicated by the flora of the Calvert formation  

USGS Publications Warehouse

The object of the present paper is to give a summary of the small flora preserved in the Miocene diatomaceous beds of the Calvert formation in the District of Columbia and Virginia, and more especially to discuss its bearing on the physical conditions of the Calvert epoch. Subsequent to the middle Eocene the next abundant marine fauna preserved along the middle Atlantic coast is that of the Calvert formation of the Chesapeake group. Although Miocene faunas so low in the stratigraphic column are known south of Virginia only in the vicinity of Porters Landing, Savannah River, closely related but younger Miocene faunas extend southward at least as far as Florida, where the containing formation rests unconformably on beds in which occur the warmer-water faunas of the Apalachicola group.

Berry, Edward Wilber

1917-01-01

2

Frogs and salamanders from the Upper Jurassic Morrison Formation (Quarry Nine, Como Bluff) of North America  

Microsoft Academic Search

Previously undescribed frog and salamander bones from the Morrison Formation, at Quarry Nine, Como Bluff, Wyoming, are reported. One anuran ilium is diagnostically discoglossid and forms the basis of Enneabatrachus hechti, gen. et sp. nov. A second ilium is diagnostically pelobatid and is the earliest record for the family Pelobatidae, although it is indeterminate below family level. Salamander vertebrae appear

Susan E. Evans; Andrew R. Milner

1993-01-01

3

The physical conditions and age indicated by the flora of the Alum Bluff formation  

USGS Publications Warehouse

The present paper has for its purpose the description of a small flora collected from the Alum Bluff formation, representing a horizon hitherto unrepresented paleobotanically in southeastern North America, and the discussion of the bearing of this flora on the physical conditions of deposition and the probable age of the deposits.

Berry, Edward Wilber

1917-01-01

4

Wake Similarity and Vortex Formation for Two-Dimensional Bluff Bodies  

NASA Astrophysics Data System (ADS)

An experimental study of the flow around a cylinder with a single straight perturbation was conducted in a wind tunnel. With this bluff body, positioned in a uniform crossflow, the vortex shedding frequency and other flow characteristics could be manipulated. The Strouhal number has been shown to be a function of the perturbation angular position, theta _{rm p}, as well as the perturbation size and Reynolds number. As much as a 50% change in Strouhal number could be achieved, simply by changing theta _{rm p} by 1^ circ. The perturbation size compared to the boundary-layer thickness, delta, was varied from approximately 1delta to about 20delta. The Reynolds number was varied from 10,000 to 40,000. A detailed investigation of the characteristic Strouhal number variation has shown that varying theta_{rm p} had a significant influence on the boundary -layer separation and transition to turbulence. These significant changes occurring in the boundary-layer have been shown to cause variations in the spacing between the shear layers, base pressure, vortex formation length, drag, lift, and the longitudinal spacing between the vortices in the vortex street. The unique ability of the cylinder with a single straight perturbation to control the Strouhal number and other flow characteristics, was used to evaluate several previously proposed wake similarity concepts by Fage and Johansen(1927), Roshko(1955), Bearman(1967) and Griffin(1981). It was shown that these wake similarity concepts did not satisfactorily apply to the bluff body which was used in this study. The experimental results have shown that a wake similarity parameter, S_{rm M} = kf_{rm v}d*/U _infty has smaller variations from its mean values S_{rm Mo } = 0.39, when compared to previously proposed wake similarity parameters. The quantity, k, is the base pressure parameter, f_{rm v} , is the vortex shedding frequency, d*, is the spacing between the shear layers and U_infty , is the free stream velocity. The similarity parameter S_{rm M}, when applied to Fage and Johansen's measurements on a wide range of bluff bodies showed less variance and resulted in numbers near 0.39. The parameter, S_{rm M}, when used to evaluate the lateral-to-longitudinal stability of vortices in the vortex street was shown to favor von Karman's over Kronauer's wake stability criterion.

Nebres, Jose Luis Villafranca

5

Carbonate submarine fans and aprons in frontier petroleum region - carboniferous Calico Bluff Formation, east-central Alaska  

Microsoft Academic Search

The Calico Bluff Formation (CBF) is a spectacularly exposed 500-m thick sequence of carbonate sediment-gravity-flow deposits and interbedded fetid, organically rich lime muds and siliceous shales. CBF facies record an overall seaward-prograding, shoaling-upward section from noncyclic turbidites deposited in basin plain settings to numerous thickening- and coarsening-upward cycles of turbidites and debris flows representing outer-fan lobes or base-of-slope aprons. These

H. E. Cook; L. B. Magoon; R. G. Stanley; A. Casas

1987-01-01

6

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

USGS Publications Warehouse

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.

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

2007-01-01

7

Bluff evolution along coastal drumlins: Boston Harbor Islands, Massachusetts  

USGS Publications Warehouse

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.

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

2006-01-01

8

Calvert Cliffs tiger beetle  

NSDL National Science Digital Library

This video clip, viewable in RealPlayer, introduces students to the rare puritan tiger beetles that live in Maryland's Calvert Cliffs. The two and a half-minute clip addresses the beetle's lifecycle, focusing on its dependence on the area's beachside cliffs. A discussion of the beetle's reproduction and feeding behaviors is accompanied by footage of adult beetles on the shore and of larvae tunneling holes into the cliffs. An entomologist lists the conservation actions that need to be taken to remove the beetle from the state list of endangered species. Copyright 2005 Eisenhower National Clearinghouse

Ecducation, Johns H.; Maryland Public Television (MPT)

2004-01-01

9

Calvert Cliffs tiger beetle  

NSDL National Science Digital Library

This video clip, viewable in Windows Media Player, introduces students to the rare puritan tiger beetles that live in Maryland's Calvert Cliffs. The two and a half-minute clip addresses the beetle's lifecycle, focusing on its dependence on the area's beachside cliffs. A discussion of the beetle's reproduction and feeding behaviors is accompanied by footage of adult beetles on the shore and of larvae tunneling holes into the cliffs. An entomologist lists the conservation actions that need to be taken to remove the beetle from the state list of endangered species. Copyright 2005 Eisenhower National Clearinghouse

Johns Hopkins University. Center for Technology in Education (CTE); Maryland Public Television (MPT)

2004-01-01

10

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 false Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County, Maryland...District § 165.505 Security Zone; Calvert Cliffs Nuclear Power Plant, Chesapeake Bay, Calvert County,...

2013-07-01

11

Carbonate submarine fans and aprons in frontier petroleum region - carboniferous Calico Bluff Formation, east-central Alaska  

SciTech Connect

The Calico Bluff Formation (CBF) is a spectacularly exposed 500-m thick sequence of carbonate sediment-gravity-flow deposits and interbedded fetid, organically rich lime muds and siliceous shales. CBF facies record an overall seaward-prograding, shoaling-upward section from noncyclic turbidites deposited in basin plain settings to numerous thickening- and coarsening-upward cycles of turbidites and debris flows representing outer-fan lobes or base-of-slope aprons. These sediment-gravity-flow deposits contain abundant crinoid and bryozoan fragments and lesser amounts of calcareous green algae, other biotic components, and sand-sized detrital quartz. They interpret the flows were derived from a shallow water platform rimmed with bryozoan and crinoid meadows. The presence of detrital quartz in the mass-flow deposits indicates that this platform was probably attached to a continental landmass and was not an isolated offshore carbonate platform. Paleocurrent flow directions, in present-day coordinates, flow toward the south-southeast, toward the craton. These anomalous flow directions may be explained by block rotation or by derivation from a nearby, yet-to-be-discovered platform margin in Lisburne Group carbonates to the north and northwest. The organic content of the CBF lime muds and siliceous shales averages 5 wt. %. TAI and T/sub max/ data indicate the organic matter is well into oil generation but not overmature, and S/sub 2//S/sub 3/ ratio suggests that the CBF contains mixed gas/oil prone source rocks. These source-rock data, in conjunction with possible carbonate apron, fan, and platform margin reservoir facies, indicate the CBF is a new potential exploration target in this frontier area of Alaska.

Cook, H.E.; Magoon, L.B.; Stanley, R.G.; Casas, A.

1987-05-01

12

Paleoecology of the Quarry 9 vertebrate assemblage from Como Bluff, Wyoming (Morrison Formation, Late Jurassic)  

Microsoft Academic Search

Quarry 9 is among the richest microvertebrate localities in the Morrison Formation, having thus far produced the remains of dozens of Late Jurassic taxa. Because this lenticular claystone deposit records such a high diversity of contemporaneous species, it provides an exceptionally detailed view of their paleoecology and local paleoenvironment. In this study, we reexamined the entire Quarry 9 collection, totaling

Matthew T. Carrano; Jorge Velez-Juarbe

2006-01-01

13

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

14

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)

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.

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

2001-03-01

15

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 ...

2010-08-18

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

...operation of the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert...cooling systems for light-water nuclear power reactors,'' which requires that...exemption will not present any undue risk to public health and safety....

2011-01-10

17

Calvert Cliffs zooplankton entrainment study. Final report  

SciTech Connect

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.

Bradley, B.P.

1980-01-01

18

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

Federal Register 2010, 2011, 2012, 2013

...License Renewal for Calvert Cliffs Nuclear Power Plant, LLC's AGENCY: Nuclear...ISFSI) at the Calvert Cliffs Nuclear Power Plant site near Lusby, Maryland...September 17, 2010, Calvert Cliffs Nuclear Power Plant, LLC (CCNPP)...

2012-06-08

19

Characterization of Nonpremixed Turbulent Bluff-Body Burner Flames. Annual Report, January-December 1991.  

National Technical Information Service (NTIS)

Detailed imaging and sampling probe measurements have been performed to elucidate the mechanisms controlling combustion and pollutant formation in jet, unconfined and confined bluff-body flames. The experimental results have been complemented with detaile...

M. Namazian J. Kelly J. Pereira R. Schefer

1992-01-01

20

Dudley Bluffs Bladderpod ('Lesquerella congesta') Dudley Bluffs Twinpod ('Physaria obcordata') Recovery Plan.  

National Technical Information Service (NTIS)

The Dudley Bluffs bladderpod (Lespuerella conciesta) and the Dudley Bluffs twinpod (Phvsaria obcordata) are endemic to the Piceance Basin in Rio Blanco County, Colorado. These members of the mustard family are known from five major populations each, two o...

J. Anderson L. Jordan

1993-01-01

21

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

Federal Register 2010, 2011, 2012, 2013

...Federal Energy Regulatory Commission [Docket No. PR13-10-000] 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...

2012-11-26

22

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

Federal Register 2010, 2011, 2012, 2013

...ENERGY Federal Energy Regulatory Commission [Docket No. PR13-55-000] 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)...

2013-07-10

23

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

Federal Register 2010, 2011, 2012, 2013

...Application for Calvert Cliffs Nuclear Power Plant Unit 3 Notice is hereby given...1936, for the Calvert Cliffs Nuclear Power Plant (CCNPP), Unit 3 Combined...License for the Calvert Cliffs Nuclear Power Plant Unit 3: Final...

2011-05-20

24

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

Federal Register 2010, 2011, 2012, 2013

...work hour rule controls during declarations of severe weather conditions involving...following any severe weather condition. 3...Returning to Work Hour Controls Calvert Cliffs...during severe weather to ensure that work hour controls do not...

2012-08-07

25

Jackson Bluff Hydroelectric Project. Feasibility Assessment Report.  

National Technical Information Service (NTIS)

A feasibility assessment study was conducted to determine if it is economical to reinstall hydroelectric generating units at the existing Jackson Bluff Dam on the Ochlockonee River in Florida. The studies and investigations have included site reconnaissan...

1979-01-01

26

Calvert Cliffs RELAP5/MOD3/SCDAP plant deck  

SciTech Connect

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.

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

1992-12-01

27

1. SOUTH END OF CALVERT STATION. FREIGHT HOUSE IS GABLED ...  

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

1. SOUTH END OF CALVERT STATION. FREIGHT HOUSE IS GABLED STRUCTURE ON RIGHT. FIRST FLOOR FACADE ADDED IN 1946 WHEN THE PASSENGER TERMINAL SOUTH OF CENTRE STREET WAS DEMOLISHED AND ALL IT ACTIVITIES WERE TRANSFERRED TO THE FREIGHT SHED. - North Central Railroad, Baltimore Freight House, Guilford & Centre Streets, Baltimore, Independent City, MD

28

Aerodynamics of two-dimensional slotted bluff bodies  

SciTech Connect

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.

Takahashi, F.; Higuchi, H.

1988-04-30

29

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

Microsoft Academic Search

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

Wawersik

1992-01-01

30

Paleomagnetic and rock magnetic evidence for a secondary yet early magnetization in large sandstone pipes and host Late Middle Jurassic (Callovian) Summerville Formation and Bluff Sandstone near Mesita, west central New Mexico  

NASA Astrophysics Data System (ADS)

Processes responsible for the acquisition of ancient yet secondary magnetizations are important facets of the geologic history of rocks and, when the age of such magnetizations can be estimated with confidence, provide useful information on the ancient geomagnetic field. In west central New Mexico near Mesita, on the Colorado Plateau, hematitic sandstone and siltstone beds of the Middle Jurassic (Callovian) Summerville Formation and overlying Bluff Sandstone are host to numerous large (up to 100 m2 in map area) pipe-like sandstone bodies. The pipes are as strongly cemented by hematite (colors range from 10R 6/6 to 10R 3/4) as the host strata; paleomagnetic data from them and their host strata are interpreted to indicate that these rocks have been remagnetized, probably in association with sandstone pipe formation. Reverse polarity magnetizations isolated in both alternating field and thermal demagnetization from pipes are well grouped and are similar to, and not statistically distinct from, those in adjacent host strata. The grand-mean direction for 16 sites (7 sites in sandstone pipes and 9 in host strata), corrected for slight (5°) west-northwest tilt of the strata, is D = 163.0°, I = -44.3° (?95 = 2.7°, k = 169). This direction yields a pole position of 72.8°N, 135.7°E (dp = 2.1°, dm = 3.4°). Assuming a modest (i.e., ˜5°) clockwise rotation of the Colorado Plateau, the pole lies at 68.7°N, 143.8°E. Median destructive fields for the remanence in pipes and host strata are typically 40-50 mT; over 90% of the remanence is "unblocked" or removed during changes in the magnetic mineralogy by temperatures of ˜400-450°C. Isothermal remanent magnetization (IRM) acquisition data, and thermal demagnetization of "saturation" IRM, however, demonstrate that the dominant magnetic phase is of high coercivity and relatively high (above 600°C) laboratory unblocking temperatures in both sandstone pipes and host strata, yet it does not appear to contribute significantly to the characteristic remanent magnetization. The similarity in demagnetization properties between pipes and adjacent host strata, the absence of a well-defined high unblocking temperature remanence that is more typical of hematite-cemented detrital strata, and the essentially uniform reverse polarity of the remanence are all interpreted to indicate that pipes and host strata contain secondary, yet early acquired magnetizations and that magnetization acquisition continued after pipe injection. We propose that acquisition of the secondary magnetization took place in the presence of alkaline, high pH brines formed by the dissolution of the underlying gypsum-dominated Lower Jurassic Todilto Formation strata and therefore the remanence is early in age. On the basis of a comparison with Summerville and Morrison (Middle and Late Jurassic) paleomagnetic poles from rocks on the Colorado Plateau, we interpret the secondary remanence in Summerville strata and sandstone pipes near Laguna to be latest Middle to Late Jurassic in age. If realistic, this interpretation further emphasizes the importance of fluid-rock interaction in the acquisition of secondary magnetizations.

Geissman, John W.; Harlan, Stephen S.

2004-07-01

31

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

Federal Register 2010, 2011, 2012, 2013

...NRC-2012-0045] Calvert Cliffs Nuclear Power Plant, LLC; Notice of Withdrawal...Operating License The U.S. Nuclear Regulatory Commission (the Commission...the request of Calvert Cliffs Nuclear Power Plant, LLC, the licensee, to...

2012-02-23

32

The Hydrogen Economy as a Technological Bluff  

ERIC Educational Resources Information Center

|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…

Vanderburg, Willem H.

2006-01-01

33

The Hydrogen Economy as a Technological Bluff  

Microsoft Academic Search

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 is not an energy source but

Willem H. Vanderburg

2006-01-01

34

Design of Low Drag Bluff Road Vehicles  

Microsoft Academic Search

Low drag bluff road vehicle design can be obtained effectively and efficiently with a three phase approach that uses numerical simulations, scaled wind tunnel experiments and full-scale road testing. By applying this generalised method, SideWings were developed for an improved trailer underbody flow and tails for the trailer's rear-end. A combination of these aerodynamic devices resulted in fuel savings of

G. M. R. Van Raemdonck

2012-01-01

35

Paleotemperatures versus sea level: Oxygen isotope signal from fish bone phosphate of the Miocene Calvert Cliffs, Maryland  

NASA Astrophysics Data System (ADS)

The use of skeletal oxygen isotopic records for use in paleotemperature reconstruction has been hampered by the lack of independent evidence for ocean water oxygen isotopic composition. The ?18O record from homeothermic cetaceans has provided an independent estimate of ocean ?18O values represented by the Calvert and Choptank formations of Maryland. Fish teeth and bones (especially shark and ray teeth) were also collected from these sediments and provide the basis for paleotemperature estimates for represented time slices of the middle Miocene. Trends in ?18O values of the fish phosphate throughout the Calvert Formation are of opposite polarity to the trends from the cetacean bone phosphate. Paleotemperatures calculated using the cetacean proxies for ocean ?18O values sharpen the already present trend, indicating that ocean temperatures increased during episodes of greater glaciation and decreased during periods of lesser or no glaciation. When using modern average ocean values of 0‰ SMOW in the paleotemperature calculation, however, corrected paleotemperatures for the Choptank Formation do not alter the existing pattern of temperatures.

Barrick, Reese E.; Fischer, Alfred G.; Bohaska, David J.

1993-12-01

36

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

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR13-45-000] 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...

2013-04-12

37

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

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR11-87-000] 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...

2011-02-25

38

Emergency response concept plan for Pine Bluff Arsenal and vicinity  

Microsoft Academic Search

The continued storage and disposal of the United States' unitary chemical stockpile, including that portion stored at Pine Bluff Arsenal (PBA) near Pine Bluff, Arkansas, have the potential for accidental releases that could escape installation boundaries and pose a threat to civilian populations. The US Army, in conjunction with the Federal Emergency Management Agency and other federal agencies, is committed

S. A. Carnes; J. H. Sorensen; G. O. Rogers; B. L. Shumpert; R. L. Miller; A. P. Watson; C. V. Chester

1989-01-01

39

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

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.

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

1988-01-01

40

Bluff Body Flow Control Using Plasma Actuators  

NASA Astrophysics Data System (ADS)

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.

Thomas, Flint

2005-11-01

41

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

Federal Register 2010, 2011, 2012, 2013

...NUCLEAR REGULATORY COMMISSION [Docket No. 72-8; NRC-2011-0085] Calvert Cliffs Nuclear Power Plant, LLC Independent Spent Fuel...Opportunity for a Hearing for Renewal of Special Nuclear Materials License No.-2505...

2011-04-25

42

Evaluation of In Situ Combustion for Schrader Bluff  

SciTech Connect

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.

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

1999-03-11

43

Flow past Bluff Bodies by a Vortex Method.  

National Technical Information Service (NTIS)

A review of the literature on vortex methods for the representation of vortex sheets and the literature in two dimensional viscous incompressible flow past bluff bodies, mainly the circular cylinder, both experimental and numerical, with emphasis on the u...

A. P. Burrows

1990-01-01

44

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

Federal Register 2010, 2011, 2012, 2013

...Docket No. 52-016; NRC-2008-0250] 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...

2013-01-22

45

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

Federal Register 2010, 2011, 2012, 2013

...ENERGY Federal Energy Regulatory Commission [Docket No. PR11-123-000] 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,...

2011-08-26

46

Volcanic and Glacial Geology of the Miocene Minna Bluff Volcanic Complex, Antarctica  

Microsoft Academic Search

Minna Bluff is a 45-km long, 5-km wide Miocene alkaline volcanic peninsula that extends SE into the Ross Ice Shelf from the Mt. Discovery stratovolcano. Minna Bluff is a significant topographic barrier that has effectively blocked the Ross Ice Shelf and former grounded marine ice sheets from flowing southward into McMurdo Sound. In the late Miocene, Minna Bluff likely was

T. I. Wilch; W. C. McIntosh; K. S. Panter; N. W. Dunbar; J. L. Smellie; A. Fargo; M. Scanlan; M. J. Zimmerer; J. Ross; M. E. Bosket

2008-01-01

47

Pliocene age of Meyer Desert Fm. (Sirius Group) Terrestrial Biota at Oliver Bluffs, Dominion Range: a Comparison of Diatom Floras from Glacial, Wind and Ejecta Pathways  

Microsoft Academic Search

The age of the Meyer Desert Formation (Sirius Group) at Oliver Bluffs in the Transantarctic Mountains (TAM), and the terrestrial biota enclosed within these glacigene strata, has been a topic of discussion and disagreement. The Pliocene age derived from the occurrence of reworked late Miocene and early Pliocene marine diatoms within the enclosing sediments has been challenged by the assertion

D. M. Harwood

2004-01-01

48

Analysis of Calvert Cliffs reference station measurements (temperature, salinity, and dissolved oxygen)  

Microsoft Academic Search

This report applies a 'reference station method' developed for comparison of physical hydrographic variables between pre- and postoperational conditions at the Calvert Cliffs Power Plant site in the Chesapeake Bay. The analysis also evaluates the applicability of using reference station data in defining discharge mixing zones. The method can provide data on which to base regulatory standards at measurable levels,

Obremski

1974-01-01

49

Observations of Soil Wash on Steep, Unvegetated Slopes: Calvert County, Maryland.  

National Technical Information Service (NTIS)

Observations of surface erosion were made along the steep coastal cliffs of Calvert County, Maryland, in order to determine the contribution of these processes to the overall recession of the cliffs. Slope recession rates were measured with the use of ero...

J. P. Schweitzer

1993-01-01

50

Cliff erosion and bluff retreat along the California coast  

Microsoft Academic Search

While the cliffs and bluffs making up the California coastline may appear at first glance to provide a resistant barrier against the Pacific Ocean, nothing could be further from the truth. Eighteen thousand years ago the coastline of the state was as much as 45 km offshore to the west. With the melting of the icecaps and glaciers at the

Gary B. Griggs; Kiki Runyan

2003-01-01

51

Some observations on the state of bluff-body aeroelasticity  

Microsoft Academic Search

The paper comments in general upon the state of the art in bluff-body aerodynamics and aeroelasticity, nothing particularly the continuing requirements for improving the data obtained in reduced-scale experiments. While certain existing theoretical response models are gaining in sophistication - as demonstrated by theories of long-span bridge response to wind - some of the gaps to be filled therein are

Robert H. Scanlan

1997-01-01

52

Environmental radionuclide concentrations in the vicinity of the Calvert Cliffs Nuclear Power Plant: 1991-1994  

SciTech Connect

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). The purpose of this monitoring is to determine the fate, transport, and potential effects of power plant produced radionuclides. All releases during the reporting period were as a result of normal plant operations and no releases exceeded limits set by the U.S. Nuclear Regulatory Commission (USNRC).

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

1997-02-01

53

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

Microsoft Academic Search

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

P. C. Twiss; T. J. McCahon; C. G. Oviatt

1993-01-01

54

Secondary sulfate minerals from Alum Cave Bluff: Microscopy and microanalysis  

Microsoft Academic Search

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,

Lauf

1997-01-01

55

Feedback Control Applied to the Bluff Body Wake  

Microsoft Academic Search

In the present study the flow around a 2D bluff body with blunt stern is investigated experimentally and theoretically. The\\u000a goal is to decrease and stabilize drag by active control. Low-dimensional vortex models are used to describe actuation effects\\u000a on the coherent structures and the pressure field. Open-loop actuation as well as feedback control is applied using robust\\u000a H\\u000a ?-controllers

Lars Henning; Mark Pastoor; Rudibert King; Bernd R. Noack; Gilead Tadmor

56

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

57

Chemical reactions and nitrogen oxide emissions in bluff-body stabilized flames  

NASA Astrophysics Data System (ADS)

The objectives of this thesis are the investigation of the characteristics of partially premixed disk-stabilized flames. Among them, chemical reaction and NO/NOx emission in partially premixed disk-stabilized flame are the main topics. The present work includes experimental studies and numerical modelling. An intensive experimental investigation been carried out to study the characteristics of chemical reaction, NO/NOx emissions and visual characteristics of a partially premixed bluff-body stabilized flame. In order to understand better the mechanism of chemical reaction and the NOx, formation of the flame, two factors, the Spatial Reaction Index (SRI) and the Modified Mixture Fraction (MMF), have been established respectively. A numerical model for the disk-stabilized flame, which provided the information about its detailed chemical reactions and NOx formation by burning butane in air, has been developed. Predictions obtained by using the model were compared with the experimental results. By carrying out the preset experimental and numerical studies, I have made the following contributions towards a better understanding of the partially premixed bluff body stabilized flame. (1) A non-traditional approach, the image-processing technique, has been applied to analyze the visual characteristics of the partially premixed disk-stabilized flame. (2) The present experimental results provide an excellent database for predicting the NO/NOx formation mechanisms in the disk-stabilized flame. (3) A Spatial Reaction Index (SRI), which is the ratio of O2 chemical reaction rate to O2 mass transfer rate, based on the present experimental results has been proposed. (4) A Modified Mixture Fraction (MMF), which is the mess ratio of the carbon containing species to all gaseous species, has also been proposed based on the present experimental findings. (5) A numerical model of the disk-stabilized flame, which is based on the calculation codes of a Perfect Stirred Reactor, has been developed. (Abstract shortened by UMI.)

Shen, Hong Mei

2001-07-01

58

Bluff Body Fluid Interactions Modelling for Micro Energy Harvesting Application  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

59

Linking process-based measurements and observations with bluff recession estimates and inferred bluff erosion mechanisms on the Chukchi coast, North Slope, Alaska  

NASA Astrophysics Data System (ADS)

Recent work to the east of Pt. Barrow on the North Slope of Alaska’s Arctic coast and along the Beaufort Sea coast has shown staggering rates of bluff recession. Bluff recession is also prevalent on the Chukchi Sea coast to the west of Pt. Barrow, but current knowledge suggests that the recession rates are smaller than those on the Beaufort coast. It has been suggested that the bluffs on the Beaufort Sea are ‘melting’ away while bluff erosion on the Chukchi Sea coast is driven by storm events. Although hypothesis have been put forward as to the underlying reason for the variation in the recession rates, detailed knowledge of the forcing and resisting mechanisms responsible for bluff erosion on the Chukchi coast has not been investigated closely. In this study we investigate various processes driving bluff erosion on the Chukchi coast of northwestern Alaska with the goal of identifying the dominant forcing mechanisms. During a field study conducted in late-summer 2009, three Arctic coastal bluff failure modes were inferred from observations and ground-based lidar along a 10-km stretch of the Chukchi Sea. The three failure modes can be summarized as (1) thaw-slump of originally ice-bonded clay and sand resulting in a downward-driven failure block, (2) cantilever beam failure of ice-bonded peat and clay tundra blocks bounded by ice-wedges, and (3) retrogressive landslides of thawed sand-rich sediment layers resulting in steeply inclined bluff faces. Comparison of bluff edge lines from historical aerial photographs indicate that recession rates between 1955 and 1997 were approximately 60% greater for the section of coast dominated by ice wedges and undergoing cantilever beam failure (type-2 failure mode). The type-2 failure is believed to be the dominant mechanism by which bluffs erode on the Beaufort coast. The type-2 failure mechanism is driven by thermal niching, whereby warm air or seawater melts the permafrost at the base of the bluff leaving an overhang and an impending cantilever beam. On the Chukchi coast within the study area, the type-2 cantilever beam failure mode appears to be associated with surficial deposits of marine sand while the majority of the study area consists of marine beach deposits that are eroding by thaw-slump and retrogressive bluff failures. Based on visual observations, historical temperatures, time-lapse photography, and nearshore wave climate measurements made during ice free conditions, thaw-slump and retrogressive bluff failures appear to be driven by both thermal niching and mechanical erosion due to wave impact at the base of the bluffs. In order to better identify the presence and relative importance of these processes on bluffs undergoing thaw-slump and retrogressive failures, measured temperature gradients of bluff material and sea water along with inferred wave impact at the base of the bluff are evaluated. Measured wave conditions and water elevations are used as boundary inputs to calculate wave run-up heights, storm-surge levels, and infer impact with the base of the bluff.

Erikson, L. H.; Storlazzi, C. D.; Collins, B. D.

2009-12-01

60

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 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207...REGULATIONS § 207.169 Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and...

2013-07-01

61

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 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207...REGULATIONS § 207.169 Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and...

2010-07-01

62

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207...REGULATIONS § 207.169 Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and...

2009-07-01

63

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

Microsoft Academic Search

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

Jason M. Ortega; Kambiz Salari

2005-01-01

64

Vortices behind a bluff body with an upswept aft section in ground effect  

Microsoft Academic Search

The vortices behind a bluff body equipped with an upswept aft section are studied in a model test. The bluff body operates in close proximity to ground. The principle measurement technique is laser Doppler anemometry (LDA), which is supported by surface flow, pressure and force measurements. The upswept surface has an angle of 17° to horizontal. With the presence of

X Zhang; A Senior; A Ruhrmann

2004-01-01

65

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170...NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a) The level of the...

2009-07-01

66

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170...NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a) The level of the...

2013-07-01

67

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. 207.170 Section 207.170...NAVIGATION REGULATIONS § 207.170 Federal Dam, Oklawaha River, Moss Bluff, Fla.; pool level. (a) The level of the...

2010-07-01

68

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

Federal Register 2010, 2011, 2012, 2013

...ENERGY Federal Energy Regulatory Commission [Docket No. PR10-28-000] 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...

2010-06-15

69

78 FR 39310 - Niobrara Confluence and Ponca Bluffs Conservation Areas, NE and SD; Draft Environmental Impact...  

Federal Register 2010, 2011, 2012, 2013

...FXRS1265066CCP0--134-FF06R06000] Niobrara Confluence and Ponca Bluffs Conservation...extending the public comment period for the Niobrara Confluence and Ponca Bluffs Conservation...nps.gov/niob-ponca. Email: niobrara_ponca@fws.gov. In-Person...

2013-07-01

70

Environmental radionuclide concentrations in the vicinity of the Calvert Cliffs nuclear power plant: 1987-1990. Final report  

SciTech Connect

The Maryland Power Plant Research Program monitors concentrations of natural, weapons, and power plant produced radionuclides in environmental samples collected from the Chesapeake Bay system in the vicinity of the Calvert Cliffs Nuclear Power Plant (CCNPP). The purpose of this monitoring is to determine the fate, transport, and potential effects of power plant produced radionuclides. This data report contains a description of monitoring activities and data collected during the period 1987 through 1990 and is the fifth in a series reporting monitoring results initiated at Calvert Cliffs in 1975.

Stanek, M.A.; McLean, R.I.

1995-12-20

71

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

SciTech Connect

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.

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

1985-07-01

72

Turbulence Structure Within and Above a Canopy of Bluff Elements  

NASA Astrophysics Data System (ADS)

Measurements of turbulence structure in a wind-tunnel model canopy of bluff elements show many of the features associated with vegetation canopies and roughness sublayers but also display features more characteristic of the inertial sublayer (ISL). Points of similarity include the existence of an inflexion point in the space-time averaged streamwise velocity at the canopy top, the variation with height of turbulent second moments and the departure of the turbulent kinetic energy budget from local equilibrium in and just above the canopy. Quadrant analysis shows characteristic dominance of sweep over ejection events within the canopy although sweeps are more frequent than usually seen in vegetation canopies. Points of difference are a u', w' correlation coefficient that is closer to the ISL value than to most canopy data, and a turbulent Prandtl number midway between canopy and ISL values. Within the canopy there is distinct spatial partitioning into two flow regimes, the wake and non-wake regions. Both time-mean and conditional statistics take different values in these different regions of the canopy flow. We explain many of these features by appealing to a modified version of the mixing-layer hypothesis that links the dominant turbulent eddies to the instability of the inflexion point at canopy top. However, it is evident that these eddies are perturbed by the quasi-coherent wakes of the bluff canopy elements. Based upon an equation for the instantaneous velocity perturbation, we propose a criterion for deciding when the eddies linked to the inflexion point will dominate flow structure and when that structure will be replaced by an array of superimposed element wakes. In particular, we show that the resemblance of some features of the flow to the ISL does not mean that ISL dynamics operate within bluff-body canopies in any sense.

Böhm, Margi; Finnigan, John J.; Raupach, Michael R.; Hughes, Dale

2013-03-01

73

Status report on Cathedral Bluffs Shale Oil Company  

SciTech Connect

The Cathedral Bluffs (CB) Project plans to extract shale oil from the deposit-rich Piceance Basin region in western Colorado. The current plans for the project are to use a combination of Union Oil Company's above-ground retorting technology and Occidental Oil Shale's underground Modified In Situ technology. The present design basis is for approximately 14,000 barrels per day of high quality synthetic crude. In July 1983, partners for the project signed a Letter of Intent with the United States Synthetic Fuels Corporation (SFC) for a total assistance package of $2.19 billion.

Phillips, J.B.

1985-01-01

74

Blowoff dynamics of bluff body stabilized turbulent premixed flames  

SciTech Connect

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)

Chaudhuri, Swetaprovo; Kostka, Stanislav; Renfro, Michael W.; Cetegen, Baki M. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, U-3139, Storrs, CT 06269 (United States)

2010-04-15

75

Piezoelectric energy harvesting from transverse galloping of bluff bodies  

NASA Astrophysics Data System (ADS)

The concept of harvesting energy from transverse galloping oscillations of a bluff body with different cross-section geometries is investigated. The energy is harvested by attaching a piezoelectric transducer to the transverse degree of freedom of the body. The power levels that can be generated from these vibrations and the variations of these levels with the load resistance, cross-section geometry, and freestream velocity are determined. A representative model that accounts for the transverse displacement of the bluff body and harvested voltage is presented. The quasi-steady approximation is used to model the aerodynamic loads. A linear analysis is performed to determine the effects of the electrical load resistance and the cross-section geometry on the onset of galloping, which is due to a Hopf bifurcation. The normal form of this bifurcation is derived to determine the type (supercritical or subcritical) of the instability and to characterize the effects of the linear and nonlinear parameters on the level of harvested power near the bifurcation. The results show that the electrical load resistance and the cross-section geometry affect the onset speed of galloping. The results also show that the maximum levels of harvested power are accompanied with minimum transverse displacement amplitudes for all considered (square, D, and triangular) cross-section geometries, which points to the need for performing a coupled analysis of the system.

Abdelkefi, A.; Hajj, M. R.; Nayfeh, A. H.

2013-01-01

76

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

Federal Register 2010, 2011, 2012, 2013

...Docket No. 52-016; NRC-2008-0250] UniStar Nuclear Energy; Combined License Application for Calvert Cliffs...Plant, Unit 3; Exemption 1.0 Background: UniStar Nuclear Energy (UNE) submitted to the U.S. Nuclear...

2011-12-29

77

Combustion heat release effects on asymmetric vortex shedding from bluff bodies  

NASA Astrophysics Data System (ADS)

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

Cross, Caleb Nathaniel

78

Plasma actuators for bluff body flow control  

NASA Astrophysics Data System (ADS)

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.

Kozlov, Alexey V.

79

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

Federal Register 2010, 2011, 2012, 2013

...experience scenic bluffs, forests, grasslands, and traditional rural lifestyles critical to the local communities. Niobrara Confluence...resources to enhance conservation; enhance recreation; increase tourism; instill new money into local economies; improve quality...

2013-04-08

80

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

Microsoft Academic Search

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

Jason M. Ortega; Kambiz Salari

2006-01-01

81

Coastal Bluff Recession and Impacts on Littoral Transport: Special Reference to Montauk, NY  

Microsoft Academic Search

Recession of coastal bluffs supply the initial sediment to the littoral zone along the south shore of Long Island, NY. Analysis of profile data collected as part of the Atlantic Coast of New York Monitoring Program indicated volumetric recession rates vary between headlands and coves along the Montauk province ranging from 1.0 m3\\/m\\/yr to 19.6 m3\\/m\\/yr. Stabilization of the bluffs

Frank S. Buonaiuto Jr; Henry Bokuniewicz

82

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

SciTech Connect

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.

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

2005-12-27

83

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

DOEpatents

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.

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

2005-08-09

84

Suppression of combustion instability by geometrical design of the bluff-body stabilizer  

SciTech Connect

Passive control methods were used to suppress combustion instability in a combustor with a bluff-body stabilizer. The instabilities in this combustor are excited by interaction between vortices shed downstream of the stabilizer and the combustion chamber acoustic modes. The passive control methodology was to change the geometrical design of the stabilizer in a manner that will disrupt the formation or reduce the coherence of the wake vortices, thus eliminating the source of the instability excitation. Two geometrical designs were tested and compared to the regular baseline disk stabilizer. The first was a corrugated stabilizer that promotes the shedding of longitudinal vortices from the stabilizer`s base. These vortices induce azimuthal instability in the axisymmetric wake vortices and accelerates their breakdown. The second configuration was a multistep cone that was shown to enhance the production of small-scale turbulence in the flow. Both methods were effective in the suppression of the pressure oscillations and reduced significantly the range of unstable combustion without adversely affecting the lean and rich flammability limits. The optimal configuration was the multistepped cone stabilizer. The orientation of the stabilizers and the effect of central ventilations were studied as well as the instability mode characteristics. 16 refs.

Gutmark, E.J.; Schadow, K.C.; Nina, M.N.R.; Pita, G.P.A. [Naval Air Warfare Cent, China Lake, CA (United States)

1995-05-01

85

Failure modes of thawing permafrost bluffs on the Chukchi Sea coast, Alaska  

NASA Astrophysics Data System (ADS)

Increasing Arctic temperatures from global climate change are well documented, however an understanding of their influences on specific geomorphic processes affecting arctic coastal bluff erosion are much less well understood. Coastal bluffs in natural settings typically erode through a suite of geomorphic processes including both marine (e.g. wave action) and terrestrial (e.g. groundwater seepage) forces. In arctic settings, thermal influences which affect both terrestrial and marine ice content also govern these processes and create additional inputs to instability and erosion. Here, we investigate the failure modes of coastal bluffs along a 10 km length of the Chukchi Sea in northwestern Alaska with the goal of identifying the predominant processes and their topographic signatures. We use high-resolution terrestrial lidar surveying, georeferenced simultaneously via geodetic-grade GPS measurements, to analyze cross-sections of the bluffs and compare these to observations of the predominant failure modes identified during recent field work. An effort is made to link the processes directly to the mapped stratigraphy of the bluffs. Our observations identify at least three different failure modes: (1) downward-driven spreads associated with thaw-slump activity in originally ice-bonded clay and sand, (2) topples of ice-wedge bounded, cantilevered ice-bonded peat and clay tundra blocks, and (3) retrogressive, steeply inclined translational ice-thawed sand landslides. All three failure modes are associated with warming air temperatures while the last two modes also appear to be initiated by thermal niching and/or wave action at the base of the bluff. Identification of the predominant failure modes along this coast will assist with further investigations aimed at predicting trends of both short- and long-term coastal erosion and their impact on local communities and wildlife habitats. Terrestrial lidar data collection of Arctic coastal bluff failure modes along the Chukchi Sea, Alaska

Collins, B. D.; Erikson, L. H.; Reiss, T.

2009-12-01

86

Driftwood dropstones in mid-Miocene shallow marine strata (Calvert Cliffs, Maryland Coastal Plain): An erratic lithic pebble des not necessarily a cold paleoclimate make  

NASA Astrophysics Data System (ADS)

Erratic lithic pebbles recovered from marine sediments are routinely identified as Ice-Rafted Debris (IRD), transported by icebergs, sea ice, or river ice discharged into the sea. We suggest this is not always the transport mechanism--especially when other paleoclimatologic proxies indicate relatively warm climates and extensive forests in the pebble provenance regions. Rivers could transport significant amounts of pebbbles as driftwood dropstones, trapped in the roots of trees and later uprooted in floods and carried out to sea. To illustrate a likely example of Tree-Rafted Detritus (TRD), we analyzed a collection of lithic erratics collected from three beds in eroding (5-10 cm/a) mid-Miocene (Serravalian)shallow marine deposits (upper Calvert Formation,Chesapeake Bay, southern Maryland), which predate the ca. 13.9 Ma global cooling and expansion of the East Antarctic Ice Sheet. The ca. 220 specimens (1-10 cm in diameter) are extremely variable in lithology and degree of roundness. The great majority are evidently of Piedmont provenance and were probably rafted ca. 120 km to the collection site from the paleo-mouth of the Susquehanna River, floated out to sea and carried south by the Miocene Coastal Current. River ice can probably be ruled out as the transport mechanism, given the prevailing warm temperate to subtropical climates. Common carbonized wood fragments (typically 2 x 10 cm in outcrop dimensions) in the same strata containing the erratics support driftwood transport. The lithic erratics may serve as independent tracers for terrestrial vertebrate fossils, transported into the Calvert Sea (Atlantic Ocean) by the 'float and bloat' mechanism.(Allowance has to be made for ca. 20 m/Ma post-middle Miocene source region denudation). However,only 3% of the clasts (mostly quartz diorite gneiss)could be readily related to a specific outcrop--the Port Deposit Gneiss near the modern mouth of the Susquehanna River. We suggest that driftwood transport be considered as a possibly significant alternative source of lithic erratics found in e.g. Middle Eocene Arctic Basin sediments--especially given that this basin was largely enclosed and fed by large rivers draining vast forests.

Vogt, P. R.; Parrish, M.

2009-12-01

87

Jackson Bluff Hydroelectric Project: Final operation and maintenance report  

SciTech Connect

The Jackson Bluff Hydroelectric Project is the first hydroelectric plant developed by the City of Tallahassee. The project is located on the Ochlockonee River approximately 66 miles upstream from its mouth at the Gulf of Mexico and approximately 20 miles west-southwest of the city of Tallahassee, Florida. The original hydroelectric generating facility with a total capacity of 8800 kw was retired in 1970. In the late seventies, the Department of Energy (DOE) classified the site as potential site for the Hydroelectric Demonstration Project. The City of Tallahassee submitted a proposal to DOE to reinstall generating equipment and operate the facility. The proposal was approved and after a feasibility study, the City was granted $1.75 million by DOE to meet approximately 15/percent/ of the total project cost. The existing powerhouse and intake serves to utilize three vertical-shaft turbines, two fixed blade and one adjustable blade propeller (Kaplan). The two fixed blade turbines drive a 4440 kw synchronous generator each and the adjustable blade propeller drives a 3438 kw synchronous generator. The plant design flow is 5200 cubic feet per second and the rated net head for the turbines is 32 feet. The runner diameters are 125.8 inches (fixed blade) and 104.7 inches (adjustable blade). In early 1983, with the proposal approved and the feasibility study completed, the City of Tallahassee took over the responsibility of the project. The rehabilitation work started in July 1983, and was completed in early 1986.

Hinton, J.; deMontmollin, F.

1988-03-01

88

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

National Technical Information Service (NTIS)

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 ha...

D. L. Brien M. E. Reid

2007-01-01

89

Wall effect on fluid-structure interactions of a tethered bluff body  

NASA Astrophysics Data System (ADS)

Wind tunnel experiments have shown an unexplained amplification of the free motion of a tethered bluff body in a small wind tunnel relative to that in a large wind tunnel. The influence of wall proximity on fluid-structure interaction is explored using a compound pendulum motion in the plane orthogonal to a steady freestream with a doublet model for aerodynamic forces. Wall proximity amplifies a purely symmetric single degree of freedom oscillation with the addition of an out-of-phase force. The success of this simple level of simulation enables progress to develop metrics for unsteady wall interference in dynamic testing of tethered bluff bodies.

Sharma, Sumant; Raghav, Vrishank; Komerath, Narayanan; Smith, Marilyn

2013-11-01

90

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

NASA Astrophysics Data System (ADS)

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.

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

2005-03-01

91

Measurements and Modeling of a Bluff-body Stabilized Flame. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

An axisymmetric bluff body stabilized non-premixed turbulent flame of 27.5% CO/ 32.3% H2/ 40.2% N2-in-air was investigated. The recirculation zone stabilized the flame and provided greater strain rates than possible in jet or even piloted-jet flames. Majo...

S. M. Correa Anil Gulati

1992-01-01

92

Factors Controlling Rates of Bluff Recession at Two Sites on Lake Michigan  

Microsoft Academic Search

Empirical relationships between recession rate of bluffs and precipitation, storm frequency, lake level, deep water wave power, and wave impact height are derived for two Lake Michigan shoreline reaches in Wisconsin. Recession rates are determined from digital orthophotos constructed using historical aerial photographs at least once every decade from the 1940s to present. The recession measurements represent spatial averages of

Elizabeth A. Brown; Chin H. Wu; David M. Mickelson; Tuncer B. Edil

2005-01-01

93

Omaha-Council Bluffs Metropolitan Area Comprehensive Plan. Phase II. Housing Study and Economic Base Survey.  

National Technical Information Service (NTIS)

Phase Two of the areawide comprehensive plan for the Omaha-Council Bluffs three-county SMSA consists of a housing study and economic base survey. The housing study presents a current housing inventory for the SMSA, housing condition analysis, and an analy...

1970-01-01

94

MISERS BLUFF Electromagnetic Propagation Experiments. Final Analysis of the Laser Experiment Data.  

National Technical Information Service (NTIS)

This report describes the lidar data obtained at 1.06 and 0.53 micrometers during the MISERS BLUFF II-2 (MBII-2) tests at the Planet Test Site near Lake Havasu City, Arizona. Experiments were also performed at 10.6 micrometers, but data from these experim...

A. Rosengreen A. A. Burns

1980-01-01

95

Simulation of controlled bluff body flow with a viscous vortex method  

Microsoft Academic Search

Bluff body flows controlled in various manners are simulated with a high-resolution, gridless vortex method. Two-dimensional, unsteady, viscous simulations are utilized to illuminate the physical phenomenon underpinning certain flows of this class. Flows past a rotationally oscillating circular cylinder and flows past an elastically mounted circular cylinder are studied, providing a variety of new insights about these systems. A computational

Douglas Green Shiels

1998-01-01

96

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

USGS Publications Warehouse

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

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

1995-01-01

97

Council Bluff Reservoir, Potosi Ranger District, Clark National Forest, Iron County, Missouri.  

National Technical Information Service (NTIS)

The Council Bluff Reservoir Project in Clark National Forest proposes to build a 100 ft dam containing a 440 acre lake. The project is located at mile 134.5 on the Big River in Iron County, Missouri. Approximately two miles of stream and related ecosystem...

1971-01-01

98

Volcanic and Glacial Geology of the Miocene Minna Bluff Volcanic Complex, Antarctica  

NASA Astrophysics Data System (ADS)

Minna Bluff is a 45-km long, 5-km wide Miocene alkaline volcanic peninsula that extends SE into the Ross Ice Shelf from the Mt. Discovery stratovolcano. Minna Bluff is a significant topographic barrier that has effectively blocked the Ross Ice Shelf and former grounded marine ice sheets from flowing southward into McMurdo Sound. In the late Miocene, Minna Bluff likely was a terminal pinning point for the Ross Ice Shelf. The peninsula is composed of many overlapping volcanic centers and is intensely eroded along south facing McIntosh Cliffs and east-facing Minna Hook cliffs, providing well-exposed 1000-m-thick stratigraphic sections. Mapping and sampling during 2006-7 and 2007-8 field seasons provide records of pulsating volcanism, glacial erosion, and glacial deposition in the Ross Embayment during the construction of Minna Bluff between 12 and 8 Ma. The volcanic stratigraphy along the Minna Hook cliffs contrasts markedly with the stratigraphy of McIntosh Cliffs. Stratigraphic alternations between subaerial lava and breccia and thin subaqueous pillow lava and hyaloclastite are concentrated in the lower parts of the Minna Hook sections. These alternations are interpreted as representing syneruptive interactions between lava flows and ephemeral local ice. The lower parts of the Minna Hook sequences also include widespread, undulating unconformities mantled by glacial and fluvial sediments. These unconformities and associated sediment record at least two broader scale grounded ice sheet events which are tightly constrained by 40Ar/39Ar ages (see Fargo et al, this volume). Upper parts of the Minna Hook sections resemble the McIntosh Cliff sequences, in being dominated by subaerial lava, breccia, and vent complexes and lacking subaqueous volcanic lithofacies, sedimentary rocks, and unconformities. More than 50 partially eroded, subaerially erupted domes and cinder cones were mapped and are preserved on the bluff top. An explosively erupted hydrovolcanic deposit forms a small nunatak in the saddle between Mt. Discovery and Minna Bluff. Minna Bluff rocks form a basanite to phonolite alkaline volcanic lineage. Phonolite and tephriphonolite domes are common in the lower third of the Minna Hook cliff sections and along the top of the Minna Hook, basanite to phonotephrite lavas are the dominant lithologies overall. Ongoing geochronology, geochemistry, and lithofacies analysis of more than 500 samples will provide a detailed glacial and volcanic record of this important region.

Wilch, T. I.; McIntosh, W. C.; Panter, K. S.; Dunbar, N. W.; Smellie, J. L.; Fargo, A.; Scanlan, M.; Zimmerer, M. J.; Ross, J.; Bosket, M. E.

2008-12-01

99

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

DOEpatents

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.

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

2006-07-11

100

Large eddy simulation of flows after a bluff body: Coherent structures and mixing properties  

NASA Astrophysics Data System (ADS)

This paper performs large eddy simulations (LES) to investigate coherent structures in the flows after the Sydney bluff-body burner, a circular bluff body with an orifice at its center. The simulations are validated by comparison to existing experimental data. The Q function method is used to visualize the instantaneous vortex structures. Three kinds of structures are found, a cylindrical shell structure in the outer shear layer, a ring structure and some hairpin-like structures in the inner shear layer. An eduction scheme is employed to investigate the coherent structures in this flow. Some large streaks constituted by counter-rotating vortices are found in the outer shear layer and some well-organized strong structures are found in the inner shear layer. Finally, the influences of coherent structures on scalar mixing are studied and it is shown that scalar in the recirculation region is transported outward by coherent structures.

Zhang, Pei; Han, Chao; Chen, Yiliang

2013-10-01

101

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

PubMed

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

Krajnovic, Sinisa

2009-07-28

102

Numerical analysis of high velocity flow field around the bluff body  

NASA Astrophysics Data System (ADS)

A finite-volume numerical analysis method for the solution of three-dimensional incompressible steady Navier-Stokes equations in a general curvilinear coordinate system is presented. The main solution algorithm of the method is an extension of SIMPLE algorithm to present general curvilinear coordinate formulation. The standard k-epsilon two equations turbulence model is used for the closure of the Reynolds equation. Numerical analysis are compared with experimental results for the flow field around the U-shaped gutter in a diffuser with fairly good agreement. This method is applied to the calculation of turbulent three-dimensional flows around the bluff body to obtain the velocity and temperature flow field. A feature of the velocity and temperature field around the bluff body was clarified.

Sato, Yukinori; Toh, Hidemi; Ando, Yasunori; Kawai, Masafumi

1988-12-01

103

Numerical Investigation of a Bluff-Body Stabilised Nonpremixed Flame with Differential Reynolds-Stress Models  

Microsoft Academic Search

A numerical investigation of a bluff-body stabilised nonpremixedflame, and the corresponding nonreacting flow, has been performed withdifferential Reynolds-stress models (DRSMs). The equilibrium chemistry model is employed and an assumed-shape beta function PDFapproach is used to represent the interaction between turbulence andchemistry. The Reynolds flux of the mixture fraction is obtained from atransport equation, hence a full second moment closure is

Guoxiu Li; Bertrand Naud; Dirk Roekaerts

2003-01-01

104

Water assessment of Cathedral Bluffs shale oil demonstration project, White River basin - Colorado  

SciTech Connect

This water assessment was undertaken by the U.S. Water Resources Council (WRC) under authority of the Federal Non-Nuclear Energy Research and Development Act of 1974, as amended. WRC gives an assessment for the Cathedral Bluffs Shale Oil Demonstration Project, located within the White River Basin, Colorado. The objectives of the study were to identify and document: Water requirements for the project; present and future water supply availability; and water resources impacts.

Not Available

1981-09-01

105

Wind sheltering of a lake by a tree canopy or bluff topography  

Microsoft Academic Search

A model is developed to quantify the wind sheltering of a lake by a tree canopy or a bluff. The experiment-based model predicts the wind-sheltering coefficient a priori, without calibration, and is useful for one-dimensional (1-D) lake hydrodynamic and water quality modeling. The model is derived from velocity measurements in a boundary layer wind tunnel, by investigating mean velocity profiles

Corey D. Markfort; Angel L. S. Perez; James W. Thill; Dane A. Jaster; Fernando Porté-Agel; Heinz G. Stefan

2010-01-01

106

Fundamental studies on free stream acceleration effect on drag force in bluff bodies  

Microsoft Academic Search

This paper describes fundamental studies on free stream acceleration effect on drag force in bluff bodies. The flow with gradual\\u000a velocity increase assumed an accelerated flow. The wind tunnel tests were conducted in order to investigate the difference\\u000a of aerodynamic characteristics between non-accelerated flow and accelerated flow. The experimental models were a circular\\u000a cylinder and a square cylinder. In an

Yeongbin Lee; Joohyun Rho; Kyu Hong Kim; Dong-Ho Lee

2011-01-01

107

Self-excited oscillations in the wake of two-dimensional bluff bodies and their control  

Microsoft Academic Search

The onset of Karman-vortex shedding is studied experimentally in the wake of different two-dimensional bluff bodies, namely an oblong cylinder, circular cylinders, and plates of rectangular cross section. Different control measures, such as wake heating, transverse body oscillations, and base bleed are investigated. As the steady-periodic Karman shedding has previously been identified as a limit-cycle, i.e. as self-excited oscillations, the

Michael Schumm; Eberhard Berger; Peter A. Monkewitz

1994-01-01

108

Drag and lift reduction of a 3D bluff-body using active vortex generators  

NASA Astrophysics Data System (ADS)

In this study, a passive flow control experiment on a 3D bluff-body using vortex generators (VGs) is presented. The bluff-body is a modified Ahmed body (Ahmed in J Fluids Eng 105:429-434 1983) with a curved rear part, instead of a slanted one, so that the location of the flow separation is no longer forced by the geometry. The influence of a line of non-conventional trapezoïdal VGs on the aerodynamic forces (drag and lift) induced on the bluff-body is investigated. The high sensitivity to many geometric (angle between the trapezoïdal element and the wall, spanwise spacing between the VGs, longitudinal location on the curved surface) and physical (freestream velocity) parameters is clearly demonstrated. The maximum drag reduction is -12%, while the maximum global lift reduction can reach more than -60%, with a strong dependency on the freestream velocity. For some configurations, the lift on the rear axle of the model can be inverted (-104%). It is also shown that the VGs are still efficient even downstream of the natural separation line. Finally, a dynamic parameter is chosen and a new set-up with motorized vortex generators is proposed. Thanks to this active device. The optimal configurations depending on two parameters are found more easily, and a significant drag and lift reduction (up to -14% drag reduction) can be reached for different freestream velocities. These results are then analyzed through wall pressure and velocity measurements in the near-wake of the bluff-body with and without control. It appears that the largest drag and lift reduction is clearly associated to a strong increase of the size of the recirculation bubble over the rear slant. Investigation of the velocity field in a cross-section downstream the model reveals that, in the same time, the intensity of the longitudinal trailing vortices is strongly reduced, suggesting that the drag reduction is due to the breakdown of the balance between the separation bubble and the longitudinal vortices. It demonstrates that for low aspect ratio 3D bluff-bodies, like road vehicles, the flow control strategy is much different from the one used on airfoils: an early separation of the boundary layer can lead to a significant drag reduction if the circulation of the trailing vortices is reduced.

Aider, Jean-Luc; Beaudoin, Jean-François; Wesfreid, José Eduardo

2010-05-01

109

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. [Quarterly] report, January 1, 1994March 31, 1994  

Microsoft Academic Search

The ultimate objective of this three-year research project is to evaluate the performance of the hydrocarbon miscible solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This will be accomplished through measurement of PVT and fluid properties of Schrader Bluff oil, determination of phase behavior of Schrader Bluff

1994-01-01

110

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. [Quarterly] report, January 1, 1993March 31, 1993  

Microsoft Academic Search

The ultimate objective of this three-year research project is to evaluate the performance of the hydrocarbon miscible solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This will be accomplished through measurement of PVT and fluid properties of Schrader Bluff oil, determination of phase behavior of Schrader Bluff

1993-01-01

111

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff pool, Milne Point Unit, Alaska. Quarterly report, October 1, 1993December 31, 1993  

Microsoft Academic Search

The ultimate objective of this three-year research project is to evaluate the performance of the hydrocarbon miscible solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This will be accomplished through measurement of PVT and fluid properties of Schrader Bluff oil, determination of phase behavior of Schrader Bluff

1993-01-01

112

Cooldown to residual heat removal entry conditions using atmospheric dump valves and auxiliary pressurizer spray following a loss-of-offsite power at Calvert Cliffs, Unit 1  

SciTech Connect

An investigation of cooldown using atmospheric dump valves (ADVs) and auxiliary pressurizer spray (APS) following loss-of-offsite power at Calvert Cliffs-1 showed residual heat removal entry conditions could not be reached with the plant ADVs alone. Use of APS with the plant ADVs enhanced depressurization, but still provided insufficient cooldown. Effective cooldown and depressurization was shown to occur when rated steady state flow through the ADVs was increased by a factor of four. 6 refs., 30 figs., 2 tabs.

Jenks, R.P.

1984-11-29

113

Model Investigation of Intake-Shoaling and Pump-Vibration Problems: Iowa Generation Council Bluffs Unit 3 Circulating-Water Intake.  

National Technical Information Service (NTIS)

Iowa Generation's Council Bluffs Unit-3 cooling-water pump-intake structure, located along the concave bank of the Missouri River bend near Council Bluffs, Iowa, has been experiencing two chronic problems: (1) heavy sediment deposition outside the trash r...

T. Nakato

1984-01-01

114

CHICK DIET AND DAILY ACTIVITY PATTERN OF COMMON MURRES AND BLACK-LEGGED KITTI- WAKES AT BLUFF SEABIRD COLONY, NORTON SOUND, ALASKA  

Microsoft Academic Search

At Bluff seabird colony, Norton Sound, Alaska, Common Murres (Uria aalge) fed their chicks with mostly blennies in the afternoon. Parents of Black-legged Kittiwakes (Rissa tridactyla) shifted chick guarding duties at any time of day. Foraging trip time of the murres at Bluff (3.6 hr) was about 1.4-3.3 times longer than other colonies in boreal areas.

Yutaka WATANUKI; Yasuhiko NAITO; Jay SCHAUER

115

Feedback shear layer control for bluff body drag reduction  

Microsoft Academic Search

Drag reduction strategies for the turbulent flow around a D-shaped body are examined experimentally and theoretically. A reduced-order vortex model describes the interaction between the shear layer and wake dynamics and guides a path to an efficient feedback control design. The derived feedback controller desynchronizes shear-layer and wake dynamics, thus postponing vortex formation. This actuation is tested in a wind

Mark Pastoor; Lars Henning; Bernd R. Noack; Rudibert King; Gilead Tadmor

2008-01-01

116

Feedback shear layer control for bluff body drag reduction  

Microsoft Academic Search

Drag reduction strategies for the turbulent flow around a D-shaped body are examined experimentally and theoretically. A reduced-order vortex model describes the inter- action between the shear layer and wake dynamics and guides a path to an efficient feedback control design. The derived feedback controller desynchronizes shear-layer and wake dynamics, thus postponing vortex formation. This actuation is tested in a

GILEAD T ADMOR

2008-01-01

117

Return to Coalsack Bluff and the Permian Triassic boundary in Antarctica  

NASA Astrophysics Data System (ADS)

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 ? 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.

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

2007-01-01

118

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

NASA Astrophysics Data System (ADS)

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.

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

119

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

120

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

SciTech Connect

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.

Strickland, J.H.

1989-01-01

121

Entomologic investigations of an epidemic of St. Louis encephalitis in Pine Bluff, Arkansas, 1991.  

PubMed

An epidemic of St. Louis encephalitis (SLE) occurred in Jefferson County, Arkansas during July-August 1991. At least 26 human cases were involved, with 25 cases in the town of Pine Bluff. Twelve isolates of SLE virus were obtained from mosquitoes collected in Pine Bluff between August 13 and 24: 11 from pools of Culex pipiens quinquefasciatus, resulting in a minimum infection rate of 1.6 per 1,000 (n = 6,768) for this subspecies, and one isolate from a pool of 22 mosquitoes identified as Cx. (Culex) spp. Three of the SLE-positive pools, two from Cx. p. quinquefasciatus and one from Cx. (Cux.) spp., also yielded isolates of Flanders virus. Larval surveys resulted in the collection of seven species in four genera from 28 larva-positive habitats and the identification of one significant site of Cx. p. quinquefasciatus production. Ecologic assessments conducted at 12 randomly selected residences resulted in the identification of 17 larva-positive habitats, for an average mosquito-positive habitat rate of 1.4 per residence, and a Cx. p. quinquefasciatus larva-positive habitat rate of 0.6 per residence. Aedes albopictus and Cx. p. quinquefasciatus were the species most frequently encountered in larval surveys in residential neighborhoods. PMID:8352390

Savage, H M; Smith, G C; Moore, C G; Mitchell, C J; Townsend, M; Marfin, A A

1993-07-01

122

Characteristics of the Axial and Tangential Velocities near a Rotating Bluff Body on a Platform  

NASA Astrophysics Data System (ADS)

Molecular Tagging Velocimetry (MTV) has been employed to obtain instantaneous axial and tangential velocity profiles at different vertical positions near a rotating bluff body on a platform. Measurements were made over a Reynolds number range from 4000 to 40000 based upon the characteristic body dimension and at angular accelerations varying two orders of magnitude. The evolution of the velocity profiles and flow statistics provide insights into the nature of the evolving flow field and the effect of acceleration on the global and local flow features. Our data show that the magnitude of the tangential velocity is largely independent of vertical position, is proportional to the instantaneous rotation rate and reaches a maximum value after acceleration has ceased. The magnitude of the axial velocity reaches a maximum at a fixed number of revolutions regardless of the acceleration rate and it is not proportional to the instantaneous rotation rate. Additionally, the axial velocity is in the direction of the platform for all Re and acceleration rates. These observed behavior along with previous data support a description of the evolving flow field around a rotating bluff body from start-up to steady state.

Maynes, Daniel; Robey, Harry; Klewicki, Joseph; McMurtry, Patrick

1997-11-01

123

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

USGS Publications Warehouse

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)

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

1982-01-01

124

Wind sheltering of a lake by a tree canopy or bluff topography  

NASA Astrophysics Data System (ADS)

A model is developed to quantify the wind sheltering of a lake by a tree canopy or a bluff. The experiment-based model predicts the wind-sheltering coefficient a priori, without calibration, and is useful for one-dimensional (1-D) lake hydrodynamic and water quality modeling. The model is derived from velocity measurements in a boundary layer wind tunnel, by investigating mean velocity profiles and surface shear stress development downwind of two canopies and a bluff. The wind tunnel experiments are validated with field measurements over an ice-covered lake. Both wind tunnel and field experiments show that reduced surface shear stress extends approximately 50 canopy heights downwind from the transition. The reduction in total shear force on the water surface is parameterized by a wind-sheltering coefficient that is related to the reduction of wind-affected lake area. While all measurements are made on solid surfaces, the wind-sheltering coefficient is shown to be applicable to the lake surface. Although several canopy characteristics, such as its height, aerodynamic roughness, and its porosity affect the transition of velocity profiles and surface shear stress onto a lake, a relationship based on canopy height alone provides a sufficiently realistic estimate of the wind-sheltering coefficient. The results compare well with wind-sheltering coefficients estimated by calibration of lake water temperature profile simulations for eight lakes.

Markfort, Corey D.; Perez, Angel L. S.; Thill, James W.; Jaster, Dane A.; Porté-Agel, Fernando; Stefan, Heinz G.

2010-03-01

125

3-D, bluff body drag estimation using a Green's function/Gram-Charlier series approach.  

SciTech Connect

In this study, we describe the extension of the 2-d preliminary design bluff body drag estimation tool developed by De Chant1 to apply for 3-d flows. As with the 2-d method, the 3-d extension uses a combined approximate Green's function/Gram-Charlier series approach to retain the body geometry information. Whereas, the 2-d methodology relied solely upon the use of small disturbance theory for the inviscid flow field associated with the body of interest to estimate the near-field initial conditions, e.g. velocity defect, the 3-d methodology uses both analytical (where available) and numerical inviscid solutions. The defect solution is then used as an initial condition in an approximate 3-d Green's function solution. Finally, the Green's function solution is matched to the 3-d analog of the classical 2-d Gram-Charlier series and then integrated to yield the net form drag on the bluff body. Preliminary results indicate that drag estimates computed are of accuracy equivalent to the 2-d method for flows with large separation, i.e. less than 20% relative error. As was the lower dimensional method, the 3-d concept is intended to be a supplement to turbulent Navier-Stokes and experimental solution for estimating drag coefficients over blunt bodies.

Barone, Matthew Franklin; De Chant, Lawrence Justin

2005-01-01

126

Experiments on spray interactions in the wake of a bluff body  

SciTech Connect

The dynamics of spray drop interaction within the turbulent wake of a bluff body were investigated using the Aerometrics Phase Doppler Particle Analyzer that determines both drop size and velocity. Detailed measurements obtained included spray drop size, axial and radial velocity, angle of trajectory, and size-velocity correlations. The gas-phase flow field was also ascertained via the behavior of the smallest drops. Results showed dramatic differences in drop behavior when interacting with turbulence for the various size classes. Small drops were recirculated in a pair of toroidal vortices located behind the bluff body, whereas the larger drops followed the general direction of the spray cone angle. This was documented via backlit photography. Local changes in number density were produced as a result of lateral convection and streamwise accelerations and decelerations of various drop size classes. The spray field interaction illustrated by these data effectively reveals the complexity associated with the development of the spray and casts some doubts towards attempting to describe sprays via simple integral quantities such as the Sauter Mean Diameter.

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

1987-01-01

127

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

Microsoft Academic Search

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

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

2008-01-01

128

Federal Aid Project F-025-2 (24), U.S. 65 From Pine Bluff Expressway. Pulaski County Line, Arkansas.  

National Technical Information Service (NTIS)

The project consists of the construction of a four-lane, divided, controlled, access highway between Little Rock and Pine Bluff. Air pollution and noise will increase for residents along the new route. Although a considerable number of dwellings will be r...

1971-01-01

129

Experimental translocation of the endangered shrub Apalachicola rosemary Conradina glabra to the Apalachicola Bluffs and Ravines Preserve, Florida  

Microsoft Academic Search

Apalachicola rosemary Conradina glabra Shinners is an endangered woody mint, endemic to the northwestern portion of Liberty County, Florida, USA. Because the few remaining populations of this species are on private silvicultural lands and subject to disturbance, C. glabra was reintroduced within its original range onto The Nature Conservancy's Apalachicola Bluffs and Ravines Preserve. Forty-eight plots of nine rooted cuttings

Doria R. Gordon

1996-01-01

130

Simulation of controlled bluff body flow with a viscous vortex method  

NASA Astrophysics Data System (ADS)

Bluff body flows controlled in various manners are simulated with a high-resolution, gridless vortex method. Two-dimensional, unsteady, viscous simulations are utilized to illuminate the physical phenomenon underpinning certain flows of this class. Flows past a rotationally oscillating circular cylinder and flows past an elastically mounted circular cylinder are studied, providing a variety of new insights about these systems. A computational method facilitating long-time, high- resolution vortex simulations is developed whose grid- free nature enables future extension to complex geometries. The significant fluid forces experienced by bluff bodies are of much practical concern and are induced by flowfields that are often complex. The studies in this thesis aim to contribute to the understanding of the relation between wake development and forces and how to exploit this relationship to achieve flow control. A circular cylinder undergoing rotational oscillation is known to experience a significant deviation in forces from unforced flow. Computations from Re = 150-15000 verify past experimental observation of significant drag reduction for certain forcing parameters. These simulations also illuminate the mechanism which renders this control effective-a forced boundary layer instability triggering premature shedding of multipole vortex structures. New insights were also provided by studies of flow over a model of an elastically mounted cylinder. A two- dimensional cylinder modeled as a damped oscillator can serve as an approximation to three-dimensional situations such as a cable under tension. Simulations clarified the behavior of such a two-dimensional system and, contrary to a line of classical thinking, revealed an unexpected adaptivity in wake evolution. New scaling is also suggested which better classifies these systems under certain conditions. Vortex methods are well-suited for incompressible bluff body flow in many ways. However, the handling of viscous diffusion causes complications for such simulations. A relatively unexplored approach, the core expansion method, is studied, extended, and implemented in this work in order to balance accuracy with preservation of the gridless foundation of vortex methods. This viscous technique is found to enable long-time calculations that are prohibitive with other techniques while preserving a high level of accuracy.

Shiels, Douglas Green

131

Simulation of controlled bluff body flow with a viscous vortex method  

NASA Astrophysics Data System (ADS)

Bluff body flows controlled in various manners are simulated with a high-resolution, gridless vortex method. Two-dimensional, unsteady, viscous simulations are utilized to illuminate the physical phenomenon underpinning certain flows of this class. Flows past a rotationally oscillating circular cylinder and flows past an elastically mounted circular cylinder are studied, providing a variety of new insights about these systems. A computational method facilitating longtime, high-resolution vortex simulations is developed whose grid-free nature enables future extension to complex geometries.The significant fluid forces experienced by bluff bodies are of much practical concern and are induced by flowfields that are often complex. The studies in this thesis aim to contribute to the understanding of the relation between wake development and forces and how to exploit this relationship to achieve flow control. A circular cylinder undergoing rotational oscillation is known to experience a significant deviation in forces from unforced flow. Computations from Re=150-15000 verify past experimental observation of significant drag reduction for certain forcing parameters. These simulations also illuminate the mechanism which renders this control effective - a forced boundary layer instability triggering premature shedding of multipole vortex structures.New insights were also provided by studies of flow over a model of an elastically mounted cylinder. A two-dimensional cylinder modeled as a damped oscillator can serve as an approximation to three-dimensional situations such as a cable under tension. Simulations clarified the behavior of such a two-dimensional system and, contrary to a line of classical thinking, revealed an unexpected adaptivity in wake evolution. New scaling is also suggested which better classifies these systems under certain conditions.Vortex methods are well-suited for incompressible bluff body flow in many ways. However, the handling of viscous diffusion causes complications for such simulations. A relatively unexplored approach, the core expansion method, is studied, extended, and implemented in this work in order to balance accuracy with preservation of the gridless foundation of vortex methods. This viscous technique is found to enable long-time calculations that are prohibitive with other techniques while preserving a high level of accuracy.

Shiels, Doug

132

3-D Slope Stability of Coastal Bluffs Incorporating 3-D Pore-Water Pressures, Seattle, WA  

NASA Astrophysics Data System (ADS)

Coastal landsliding can dramatically alter both subaerial and subaqueous environments. The stability of coastal bluffs is controlled by the interplay of 3-D variations in gravitational stress, strength, and pore-water pressure. We have developed a 3-D slope-stability analysis, SCOOPS, that allows us to search a high-resolution digital-elevation model and quantify the relative stability of all parts of the landscape by computing the stability and volume of millions of potential spherical failure surfaces. Many types of landsliding, including large, deep-seated slides, affect the steep coastal bluffs of Puget Sound in Seattle, WA. Most of the larger failures occur in glacially deposited Vashon Advance Outwash; some failures extend into the underlying mechanically weaker Lawton Clay. We use our 3-D analysis to examine the destabilizing influences of topographic form, variations in material strength, and changes in pore-water pressures created by 3-D groundwater flow fields for a coastal bluff in Seattle. By assuming homogeneous material properties without pore pressures, we can examine the effects of topography. In this scenario, the least stable areas are located on the steepest slopes or headland morphologies. However, some of these locations do not coincide with historical landslide locations. When we add heterogeneous material properties as defined by stratigraphy, the least stable areas shift to the steepest parts of the weak Lawton Clay, a result also inconsistent with historical locations. The low hydraulic conductivity of the Lawton Clay impedes groundwater flow, and elevates pore pressures at the base of the Vashon Advance Outwash, thereby increasing the potential for deep-seated landslides. We use the groundwater flow model, MODFLOW, to generate a 3-D pore-pressure field. We obtain a more realistic scenario by combining 3-D pore pressures with heterogeneous strength properties; here, areas of elevated pore pressure reflect the influence of a perched groundwater table in the Outwash as well as groundwater convergence in the coastal re-entrants. This scenario places the least stable areas in the Vashon Advance Outwash where pore pressures are locally elevated. These results agree with records of historic landslides.

Brien, D. L.; Reid, M. E.

2001-12-01

133

Three-dimensional calculations of transient fluid-thermal mixing in the downcomer of the Calvert Cliffs-1 plant using SOLA-PTS  

SciTech Connect

The SOLA-PTS code has been used to analyze transient fluid-thermal mixing in a 180/sup 0/ sector of the downcomer and a cold leg of the Calvert Cliffs-1 plant for three assumed accident scenarios. The inlet boundary conditions for these calculations were obtained from mass flow rates and temperatures that were computed in systems code studies. The results of the three-dimensional SOLA-PTS calculations indicated that a pressurized thermal shock risk was mitigated for these accident scenarios as the result of the particular circulation patterns that developed in the downcomer.

Daly, B.J.

1984-04-01

134

Simulation of bluff body stabilized flows with hybrid RANS and PDF method  

NASA Astrophysics Data System (ADS)

The motivation of this study is to investigate the turbulence-chemistry interactions by using probability density function (PDF) method. A consistent hybrid Reynolds Averaged Navier-Stokes (RANS)/PDF method is used to simulate the turbulent non-reacting and reacting flows. The joint fluctuating velocity-frequency-composition PDF equation coupled with the Reynolds averaged density, momentum and energy equations are solved on unstructured meshes by the Lagrangian Monte Carlo (MC) method combined with the finite volume (FV) method. The simulation of the axisymmetric bluff body stabilized non-reacting flow fields is presented in this paper. The calculated length of the recirculation zone is in good agreement with the experimental data. Moreover, the significant change of the flow pattern with the increase of the jet-to-coflow momentum flux ratio is well predicted. In addition, comparisons are made between the joint PDF model and two different Reynolds stress models.

Zhu, Minming; Han, Xingsi; Ge, Haiwen; Chen, Yiliang

2007-06-01

135

MISERS BLUFF Electromagnetic Propagation Experiments. Volume III-Preliminary Results of the UHF-EHF Radar-Scattering and Coherent-Transmission Experiments.  

National Technical Information Service (NTIS)

SRI International fielded four electromagnetic propagation experiments during the MISERS BLUFF II high explosive tests. Two of the four experiments are discussed here, selected preliminary results are presented, and some tentative conclusions drawn. The U...

A. A. Burns

1979-01-01

136

A comparison of dispersion calculations in bluff body wakes using LES and unsteady RANS  

SciTech Connect

Accurate modeling of the dispersion behavior of sprays or particles is critical for a variety of problems including combustion, urban pollution or release events, and splash and spray transport around heavy vehicles. Bluff body wakes are particularly challenging since these flows are both highly separated and strongly unsteady. Attempting to model the dispersion of droplets or particles interacting with bluff body wakes is even more difficult since small differences in the flow field encountered by particles can lead to large differences in the dispersion behavior. Particles with finite inertia can exhibit additional complicating effects such as preferential concentration. In this preliminary study, we consider the dispersion of solid particles in the wake of a rectangular plane at a Reynolds number (Re) of 10000 and that of droplets in the wake of a simplified tractor-trailer geometry at Re = 2 x 10{sup 6} using both the Large Eddy Simulation (LES) and Unsteady Reynolds-Averaged Navier-Stokes (URANS) turbulence modeling approaches. The calculations were performed using identical meshes for both the LES and URANS models. Particle stresses are not backcoupled to the carrier fluid velocity solution. In the case of the rectangular plane wake, the LES calculation predicts a finer-scale and more persistent wake structure than the URANS one; the resulting particle dispersion is considerably ({approx} 40%) underpredicted for low inertia particles. For the case of the simplified tractor-trailer geometry, although the LES is underresolved, similar trends are observed with strong differences in the vertical and horizontal dispersion of the smallest particles. These results suggest that it may be necessary to use LES to accurately capture the dispersion behavior of small, low inertia particles or droplets, but that URANS may be sufficient for problems in which only large particles with substantial inertia are of primary concern.

Paschkewitz, J S

2006-01-19

137

A quasi-steady 3 degree-of-freedom model for the determination of the onset of bluff body galloping instability  

NASA Astrophysics Data System (ADS)

In this paper, a quasi-steady three degree-of-freedom (3-dof) flow-induced galloping instability model for bluff-bodies is proposed. The proposed model can be applied generally for the prediction of onset of galloping instability due to negative aerodynamic damping of any prismatic compact bluff body in a fluidic medium. The three degrees of freedom refer to the bluff body's two orthogonal displacements perpendicular to its length axis and the rotation about its length axis. The model incorporates inertial coupling between the three degrees of freedom and is capable of estimating the onset of galloping instability due changes in drag, lift and moment, assuming that the bluff body is subject to uniform flow and motion. The changes may be a function of wind angle of attack ( ? ) perpendicular to bluff body's length axis, Reynolds number and a skew wind angle ( ? ) in relation to the length axis of the bluff body. An analytical solution of the instability criterion is obtained by applying the Routh-Hurwitz criterion.

Gjelstrup, H.; Georgakis, C. T.

2011-10-01

138

Flame Lift-off and Stabilization Mechanisms of Nonpremixed Jet Flames on a Bluff-body Burner  

Microsoft Academic Search

A detailed regime diagram for bluff-body stabilized flames is proposed for the flame lift-off and stabilization limits. At low fuel velocities, the flame structure is classified into three stable modes: recirculation zone flames, jet-dominated flames, and jet-like flames according to the velocity ratio of annular to central jets. Two different flame stability limits can be identified between cold and combusting

Yung-cheng Chen; Chia-chi Chang; Kuo-Long Pan; Jing-Tang Yang

1998-01-01

139

Dynamical-systems analysis and unstable periodic orbits in reacting flows behind symmetric bluff bodies  

NASA Astrophysics Data System (ADS)

Dynamical systems analysis is performed for reacting flows stabilized behind four symmetric bluff bodies to determine the effects of shape on the nature of flame stability, acoustic coupling, and vortex shedding. The task requires separation of regular, repeatable aspects of the flow from experimental noise and highly irregular, nonrepeatable small-scale structures caused primarily by viscous-mediated energy cascading. The experimental systems are invariant under a reflection, and symmetric vortex shedding is observed throughout the parameter range. As the equivalence ratio—and, hence, acoustic coupling—is reduced, a symmetry-breaking transition to von Karman vortices is initiated. Combining principal-components analysis with a symmetry-based filtering, we construct bifurcation diagrams for the onset and growth of von Karman vortices. We also compute Lyapunov exponents for each flame holder to help quantify the transitions. Furthermore, we outline changes in the phase-space orbits that accompany the onset of von Karman vortex shedding and compute unstable periodic orbits (UPOs) embedded in the complex flows prior to and following the bifurcation. For each flame holder, we find a single UPO in flows without von Karman vortices and a pair of UPOs in flows with von Karman vortices. These periodic orbits organize the dynamics of the flow and can be used to reduce or control flow irregularities. By subtracting them from the overall flow, we are able to deduce the nature of irregular facets of the flows.

Hua, Jia-Chen; Gunaratne, Gemunu H.; Kostka, Stanislav; Jiang, Naibo; Kiel, Barry V.; Gord, James R.; Roy, Sukesh

2013-09-01

140

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

NASA Astrophysics Data System (ADS)

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.

Strickland, J. H.

1992-05-01

141

Experimental investigation of the influence of inlet conditions to a bluff body wake  

NASA Astrophysics Data System (ADS)

Wind tunnel experiments have been performed in a bluff body wake with varying inlet conditions in order to enhance the physical understanding of the wake flow instability, which may lead to successful flow control and in turn reduced aerodynamic drag. The geometry consists of a rectangular-based forebody with permeable surfaces, an elliptic leading edge and a blunt trailing edge. Length, width and base height of the forebody is 2.3, 0.5 and 0.04 meters, respectively. Applying continuous suction or blowing, of different levels, through the permeable surfaces along the forebody, varies the wall-normal trailing edge velocity profile in a systematic way and hence the inlet condition to the wake. The streamwise velocity component has been measured both throughout the boundary layer and in the wake behind the body using hot-wire anemometry. High-speed stereo PIV has been used in the wake in order to collect statistics of vortical structures in the wake. The influence of boundary layer parameters on the wake flow characteristics, such as vortex shedding frequency and base pressure, will be presented.

Fallenius, Bengt; Fransson, Jens

2010-11-01

142

On the Euler stage of turbulent separation near the trailing edge of a bluff body  

NASA Astrophysics Data System (ADS)

A novel self-consistent description of time-mean two-dimensional turbulent-boundary-layer flow separating from a bluff body at arbitrarily large globally formed Reynolds numbers is presented. Contrasting with previous approaches, the theory deals with a sufficient delay of flow detachment or, correspondingly, increase of the turbulence intensity so as to both settle the question of the actual position of separation and trigger a turbulent boundary layer exhibiting a large relative streamwise velocity deficit. At separation, a generic variation of the velocity profile close to the body surface with the third power of the distance from it is detected. The Euler stage resulting from the breakdown of the incident boundary layer and governed by its vorticity is envisaged in detail. Specifically, an analytical solution to the central linear vortex-flow problem could be established. This represents the essential ingredient for the understanding of the multi-layered substructure of the flow more close to the surface, which completes the picture of gross separation at the Euler scale. Most important, the analysis does not resort to any specific turbulence closure. Concerning the canonical situation of circular-cylinder flow, a first comparison between the predicted and publicly available experimentally obtained values of the separation angle is encouraging.

Scheichl, Bernhard

2013-10-01

143

GPU accelerated simulations of bluff body flows using vortex particle methods  

NASA Astrophysics Data System (ADS)

We present a GPU accelerated solver for simulations of bluff body flows in 2D using a remeshed vortex particle method and the vorticity formulation of the Brinkman penalization technique to enforce boundary conditions. The efficiency of the method relies on fast and accurate particle-grid interpolations on GPUs for the remeshing of the particles and the computation of the field operators. The GPU implementation uses OpenGL so as to perform efficient particle-grid operations and a CUFFT-based solver for the Poisson equation with unbounded boundary conditions. The accuracy and performance of the GPU simulations and their relative advantages/drawbacks over CPU based computations are reported in simulations of flows past an impulsively started circular cylinder from Reynolds numbers between 40 and 9500. The results indicate up to two orders of magnitude speed up of the GPU implementation over the respective CPU implementations. The accuracy of the GPU computations depends on the Re number of the flow. For Re up to 1000 there is little difference between GPU and CPU calculations but this agreement deteriorates (albeit remaining to within 5% in drag calculations) for higher Re numbers as the single precision of the GPU adversely affects the accuracy of the simulations.

Rossinelli, Diego; Bergdorf, Michael; Cottet, Georges-Henri; Koumoutsakos, Petros

2010-05-01

144

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

SciTech Connect

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)

Subramanian, V.; Domingo, P.; Vervisch, L. [CORIA-CNRS and INSA de Rouen, Technopole du Madrillet, BP 8, 76801 Saint-Etienne-du-Rouvray (France)

2010-03-15

145

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

SciTech Connect

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.

Strickland, J.H.

1992-05-01

146

Modeling Turbulence Induced Skin Temperature Fluctuations of a Bluff-Rough Surface Using Surface Renewal Theory  

NASA Astrophysics Data System (ADS)

A recent analysis of high-frequency measurements of the skin temperature, Ts, of a grass surface by Katul et al.~[WRR, 1998] reveals that atmospheric turbulence ``imprints'' its statistical signature on Ts. We present a model that relates the skin temperature of a homogeneous bluff-rough surface to the properties of a turbulent atmospheric surface layer . We extend Brutsaert [WRR, 1975] surface renewal theory by explicitly solving the diffusion equation in molecular sublayers on both sides of the air-surface interface. The resulting model for Ts is a linear stochastic differential equation driven by additive colored noise---the surface layer air temperature, Ta. We demonstrate that Ts has a Gaussian, non-Markovian probability described by a Fokker-Planck equation when Ta is Gaussian. An explicit expression for the 2nd-order structure function of Ts is derived and compared with observations. In contrast with Katul et al.~who suggest that a signature of inactive eddy motion in Ts is inconsistent with the dimensional arguments of Owen and Thomson [JFM, 1963] or Yaglom and Kadar [JFM, 1974], we demonstrate that the strong coupling between Ts and Ta at low frequencies predicted by our approach resolves this apparent inconsistency.

Jeffery, C. A.; Balick, L. K.; Henderson, B.

2002-12-01

147

Self-excited oscillations in the wake of two-dimensional bluff bodies and their control  

NASA Astrophysics Data System (ADS)

The onset of Karman-vortex shedding is studied experimentally in the wake of different two-dimensional bluff bodies, namely an oblong cylinder, circular cylinders, and plates of rectangular cross section. Different control measures, such as wake heating, transverse body oscillations, and base bleed are investigated. As the steady-periodic Karman shedding has previously been identified as a limit-cycle, i.e. as self-excited oscillations, the experiments are interpreted in the framework of the Stuart-Landau model. The coefficients of the Stuart-Landau equation for the characteristic vortex shedding amplitude, i.e. the linear temporal growth rate, linear frequency, and the Landau constant, are fully determined for the two cylinders and in part for the plate. For this purpose transients are generated by suddenly switching transverse body oscillations or base bleed on or off. The analysis of these transients by a refined method based on complex demodulation provides reliable estimates of the model coefficients and yields an experimental validation of the concept that a global instability mode grows or decays as a whole. Also, it is demonstrated that the coefficients of the Stuart-Landau equation are independent of the experimental technique used to produce the transients.

Schumm, Michael; Berger, Eberhard; Monkewitz, Peter A.

1994-07-01

148

Biostratigraphy and paleoecology of Naples Bluff coastal section determined from diatoms and benthic foraminifers  

SciTech Connect

An integrated biostratigraphic and paleoecologic study of the Naples Bluff coastal section used diatoms and benthic foraminifers. This section, composed of a thick sequence of Tertiary marine rocks, represents one of the most completely exposed Neogene sections along the central coast of California. The interval examined in this study is 1800 ft thick, and represents early to late Miocene rocks and the overlying early Pliocene sediments. This sequence contains well-preserved diatom floras and benthic foraminiferal faunas that enabled us to integrate diatom biochronology with the provincial benthic foraminifer stages and to construct a sediment accumulation curve. Although generally abundant in this section, the benthic faunas are dominated by an inner marginal bathyal assemblage. However, rare deeper water assemblages occur in some samples. Five faunal events are recognized that indicate response to paleo-oceanographic and tectonic influences. The diatom assemblages in this section are relatively abundant and range from the Actinocyclus ingens zone to the Thalassiosira oestrupii zone of J.A. Barron. The diversity and abundance of these assemblages made precise age control for this section possible. A major unconformity or severely compressed interval developed between 15 and 9 Ma.

Arends, R.G.; Blake, G.H.

1986-04-01

149

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

NASA Astrophysics Data System (ADS)

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.

Tuttle, Steven G.

150

Unsteady Euler/Lagrange simulation of a confined bluff-body gas-solid turbulent flow  

NASA Astrophysics Data System (ADS)

An unsteady Euler-Lagrangian approach is adopted to predict the gaseous carrier and disperse phases flow dynamics. The turbulence is captured using two different methods, i.e. the unsteady Reynolds averaging based numerical simulation (URANS) and the large eddy simulation (LES). In the latter one, the dynamic Smagorinsky approach is used to model the sub-grid scale stresses. The time-dependent solid particle and gas phase flow properties of a confined bluff-body turbulent flow including two-way coupling effects are evaluated through comparisons with experimental data. The configuration under study features an important recirculation zone and has a mass loading of 22%. So, collision effects are not considered while tracking the disperse phase that consists of glass beads. A thermodynamically consistent turbulence modulation approach is applied for the determination of the source terms that account for the effect of particles on the turbulence level of the carrier phase. Within the URANS technique the dispersion of particles is captured by the Markov sequence approach; this model is modified by integrating a drift factor term while modeling the pressure gradient. A particular emphasis is put on the disperse phase feedback on the carrier phase and coupling procedure within each Eulerian time step along with an unsteady coupling of both codes, the (Eulerian) FASTEST3D and the (Lagrangian) LAG3D codes. Quantitative results of the disperse phase properties as well as those of the carrier phase are presented at different positions around the recirculation zone. The numerical results using both, the LES and/or the URANS delivered comparable results that agree reasonably with experimental data. However, a slight advantage of LES over URANS could be observed.

Chrigui, Mouldi; Hidouri, Ammar; Sadiki, Amsini; Janicka, Johannes

2013-10-01

151

Petrogenesis of alkaline magmas at Minna Bluff, Antarctica: evidence for multi-stage differentiation and complex mixing processes  

NASA Astrophysics Data System (ADS)

Minna Bluff, a 45-km-long peninsula that extends SE into the Ross Ice Shelf from the Mt. Discovery stratovolcano, consists of coalesced late Miocene volcanic centers formed through eruption of alkaline magma compositions in a continental rift setting. Highly silica-undersaturated compositions vary from basanite to phonolite and are exposed in volcanic features ranging from small, primitive, cinder cones to large, evolved domes. Lava compositions are more evolved on the eastern end of Minna Bluff and show an overall age progression to younger, more mafic compositions towards Mt. Discovery. Phenocrysts in lava include amphibole, plagioclase and alkali feldspar, pyroxene, olivine, magnetite and apatite. A notable feature of volcanic rocks at Minna Bluff is the presence of large (up to 5 cm) kaersutite and feldspar megacrysts and deposits that contain abundant comagmatic inclusions (kaersutite-rich) and rare mantle xenoliths. Many lavas exhibit strong disequilibrium textures, mainly expressed by breakdown rims on kaersutite that vary dramatically in thickness from crystal to crystal, but reverse compositional zoning in plagioclase is also common. Kaersutite compositions vary within a single sample and show the same compositional range and similar disequilibrium textures in rocks that vary significantly in bulk composition. The textural and compositional characteristics suggest that, for many, mixing between one or more magmas controlled the final composition of the magmas. We envisage a scenario by which some of the primitive, mantle-derived, fluid-rich magmas rose relatively unimpeded to erupt at the surface, while others stalled at or near the crust-mantle boundary and differentiated. Semi-quantitative thermobarometric results for kaersutite and clinopyroxene indicate maximum P-T-X conditions for crystallization of hydrous magmas at 5-9 kbar, ?1000°C and ?3 wt. % equiv. H2O. The P-T estimates closely match geophysical and petrologic geotherm estimates for Moho depths of ?20 km beneath the western edge of the Ross Sea. Fractionation of kaersutite, clinopyroxene and olivine from basanite near the Moho produced evolved basaltic compositions before buoyantly ascending towards the surface. A second stage of differentiation occurred to produced phonolitic compositions by fractionation of olivine, clinopyroxene, plagioclase, magnetite and apatite in the upper crust. Mixing between mafic and evolved magmas produced a range of intermediate compositions shortly before the eruption process. The ubiquity of disequilibrium textures and abundant megacrysts and comagmatic inclusions within lava deposits at Minna Bluff are direct artifacts of the mixing process. We speculate that the increase in relatively undifferentiated mafic compositions along the peninsula to the west was a response to changes in lithospheric stress, which allowed magmas to rapidly ascend.

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

2011-12-01

152

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)

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.

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

2008-12-01

153

Calvert Marine Museum  

NSDL National Science Digital Library

Facility in Solomons, MD, interprets regional paleontology, estuarine ecosystem, maritime history. Natural history exhibits: shark, whale and other fossils; aquariums, displays and outdoor trails introducing life of marshes, oyster bars, the Patuxent River and Chesapeake Bay. Maritime history exhibits include woodcarving and boatbuilding shed, oyster house, lighthouse, and traditional Chesapeake Bay wooden sailing vessel. Educational programs for school groups, Elderhostel and the public include: field trips, lectures, cruises, classes, and demonstrations. Admission and program fees apply.

154

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

SciTech Connect

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).

NONE

1995-05-01

155

Distribution of spanwise enstrophy in the near wake of three symmetric elongated bluff bodies at high Reynolds number  

NASA Astrophysics Data System (ADS)

Three elongated bluff bodies with a chord-to-thickness ratio of seven have been studied experimentally at a Reynolds number based on body thickness of 3 × 104. The defining feature of elongated bluff bodies is the interaction between trailing edge Kármán vortex shedding and leading edge separation-reattachment. We have used particle image velocimetry with different body geometries to investigate this interaction for three distinct cases: (i) small leading edge separation-reattachment length; (ii) large leading edge separation-reattachment length; and (iii) one case in between these bounds. The leading edge separation-reattachment is a significant source of spanwise enstrophy. Thus, changes in the wake enstrophy distribution are of particular interest. We have examined the time-averaged distribution and production of both the turbulent kinetic energy and the spanwise enstrophy in the near wake region utilizing proper orthogonal decomposition on the vorticity field to distinguish between turbulence and the periodic contribution of the trailing edge vortex shedding. A significant increase in the lateral distribution of spanwise enstrophy is observed - exceeding the typical bounds of the near wake - which is due to the leading edge separation-reattachment and the resulting scale of the flow at the trailing edge. As a result, strengthening the leading edge flow, which tends to weaken the trailing edge vortex shedding, may lead to enhanced mixing in the wake.

Taylor, Zachary J.; Kopp, Gregory A.; Gurka, Roi

2013-05-01

156

Water assessment reports on Rio Blanco Oil Shale Demonstration Project and Cathedral Bluffs Shale Oil Demonstration Project, White River Basin - Colorado. Appendices C and D  

SciTech Connect

This report includes: Appendices C, simulation model description and sample outputs; and appendices D, advisory committee meeting minutes. This data pertains to water supply assessments made for the Rio Blanco oil shale demonstration project, and Cathedral Bluffs shale oil demonstration project which are located in Utah and Colorado.

Not Available

1981-09-01

157

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

Microsoft Academic Search

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

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

2001-01-01

158

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

NASA Astrophysics Data System (ADS)

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.

Porumbel, Ionut

159

Cathedral Bluffs: pushing to the outer limits for 94,000 bbl/d of shale oil  

SciTech Connect

The modified in situ (MIS) technology to be used by Cathedral Bluffs Shale Oil Co. is an extractive design, demanding some of the most imaginative engineering and planning yet devised for an underground project. The MIS system involves conventional LHD or conveyor-assisted LHD mining of a 15 to 25% void volume on 3 levels of a high rise retort (162 x 162 x 270 ft) to create voids in the oil shale beds. The remaining oil shale is rubblized by blasting into the voids. The rubble in the MIS retort is ignited using fuel and air injected through boreholes that tap the top of the retort. Hot inert gas burners also are being examined. The development of the project, R6 blast design, and rubblizing of retorts 7 and 8 are described. A schematic of the Logan Wash mine and an idealized sketch of retort 6 blasting sequence are included.

Not Available

1981-06-01

160

Strouhal-Reynolds number relationship for bluff-body flows numerically simulated by an artificial boundary method.  

PubMed

The incidence of the numerical resolution and the blockage effect are investigated in an embedding method for solving bidimensional bluff body flows. This method consists of using an artificial boundary instead of imposing exact conditions on the body surface. It requires us to define a blur frontier ratio and a blockage effect ratio. The blockage effect ratio is found using the mean flow of a circular cylinder directly. The blur frontier ratio is obtained by comparison of the present method with another numerical method where explicit boundary conditions on the body are imposed. For this ratio, the investigations are based on the flow past a square cylinder which discard the uncertainty on the surface of the body for the embedding method. Hence, the two factors allow the transformations of the Strouhal and the Reynolds numbers for the flow past a circular cylinder. The universal Strouhal-Reynolds number relationship of the circular cylinder is finally recovered. PMID:14682839

Ravoux, J F; Provansal, M; Nadim, A; Schouveiler, L

2003-11-20

161

Comparison of submodels for conditional velocity and scalar dissipation in CMC simulation of piloted jet and bluff-body flames  

SciTech Connect

No meaningful difference is observed between the predictions with the conditional velocity modeled by linear scaling and gradient diffusion assumption for the test flames under consideration. The AMC and Girimaji's model for CSDR show similar results, while the pdf integration method results in an asymmetric profile with some deviation from the other two. The difference tends to decrease as mixing proceeds, to result in a lower level of scalar dissipation at downstream locations. Reasonable agreement is achieved with measured scalar dissipation rates at different axial locations for the Sandia Flame D, while direct comparison is difficult due to radially averaged pdfs and no measured scalar dissipation rates being available for the Sydney bluff-body flame.

Sreedhara, S.; Lee, Y.; Huh, Kang Y. [Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784 (Korea); Ahn, D.H. [Power Generation Research Lab, Korea Electric Power Research Institute, Daejeon, 305-380 (Korea)

2008-01-15

162

Technical evaluation of the adequacy of station electric distribution systems voltages for the Calvert Cliffs Nuclear Power Plant, Units 1 and 2. Docket Nos. 50-317, 50-318  

SciTech Connect

This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the Calvert Cliffs Nuclear Power Plant, Units 1 and 2. The evaluation is to determine if the onsite distribution system in conjunction with the offsite power sources has sufficient capacity to automatically start and operate all Class 1E loads within the equipment voltage ratings under certain conditions established by the Nuclear Regulatory Commission. The analyses submitted demonstrate that adequate voltage will be supplied to the Class 1E equipment under worst case conditions.

Selan, J. C.

1982-04-09

163

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

USGS Publications Warehouse

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

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

2003-01-01

164

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

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.

Johnson, K.A.; Mayer, L. (Miami Univ., Oxford, OH (United States). Dept. of Geology)

1993-03-01

165

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. Final report  

SciTech Connect

The National Energy Strategy Plan (NES) has called for 900,000 barrels/day production of heavy oil in the mid-1990s to meet our national needs. To achieve this goal, it is important that the Alaskan heavy oil fields be brought to production. Alaska has more than 25 billion barrels of heavy oil deposits. Conoco, and now BP Exploration have been producing from Schrader Bluff Pool, which is part of the super heavy oil field known as West Sak Field. Schrader Bluff reservoir, located in the Milne Point Unit, North Slope of Alaska, is estimated to contain up to 1.5 billion barrels of (14 to 21{degrees}API) oil in place. The field is currently under production by primary depletion; however, the primary recovery will be much smaller than expected. Hence, waterflooding will be implemented earlier than anticipated. The eventual use of enhanced oil recovery (EOR) techniques, such as hydrocarbon miscible solvent slug injection process, is vital for recovery of additional oil from this reservoir. The purpose of this research project was to determine the nature of miscible solvent slug which would be commercially feasible, to evaluate the performance of the hydrocarbon miscible solvent slug process, and to assess the feasibility of this process for improved recovery of heavy oil from Schrader Bluff reservoir. The laboratory experimental work includes: slim tube displacement experiments and coreflood experiments. The components of solvent slug includes only those which are available on the North Slope of Alaska.

NONE

1995-11-01

166

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

SciTech Connect

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.

Mendenhall, V.M.

1991-04-01

167

Large Eddy Simulations of forced ignition of a non-premixed bluff-body methane flame with Conditional Moment Closure  

SciTech Connect

Large Eddy Simulations (LES) of forced ignition of a bluff-body stabilised non-premixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A three-dimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonable accuracy with both mechanisms, but the detailed mechanism resulted in expansion rates closer to the experiment. Moreover, the distribution of OH was predicted qualitatively accurately, with patches of high and low concentration in the recirculation zone during the ignition transient, consistent with experimental data. The location of the spark relative to the recirculation zone was found to determine the pattern of the flame propagation and the total time for the flame stabilisation. The size was also an important parameter, since it was found that the flame extinguishes when the spark is very small, in agreement with expectations from experiment. The stabilisation mechanism of the flame was dominated by the convection and sub-grid scale diffusion of hot combustion products from the recirculation zone to the cold gases that enter the burner, as revealed by analysis of the CMC equation. (author)

Triantafyllidis, A.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Eggels, R.L.G.M. [Rolls Royce Deutschland, Blankenfelde-Mahlow (Germany)

2009-12-15

168

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)

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.

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

169

Ground-water conditions in the Dutch Flats area, Scotts Bluff and Sioux Counties, Nebraska, with a section on chemical quality of the ground water  

USGS Publications Warehouse

The U.S. Department of the Interior (DOI) studied contamination induced by irrigation drainage in 26 areas of the Western United States during 1986-95. Comprehensive compilation, synthesis, and evaluation of the data resulting from these studies were initiated by DOI in 1992. Soils and ground water in irrigated areas of the West can contain high concentrations of selenium because of (1) residual selenium from the soil's parent rock beneath irrigated land; (2) selenium derived from rocks in mountains upland from irrigated land by erosion and transport along local drainages, and (3) selenium brought into the area in surface water imported for irrigation. Application of irrigation water to seleniferous soils can dissolve and mobilize selenium and create hydraulic gradients that cause the discharge of seleniferous ground water into irrigation drains. Given a source of selenium, the magnitude of selenium contamination in drainage-affected aquatic ecosystems is strongly related to the aridity of the area and the presence of terminal lakes and ponds. Marine sedimentary rocks and deposits of Late Cretaceous or Tertiary age are generally seleniferous in the Western United States. Depending on their origin and history, some Tertiary continental sedimentary deposits also are seleniferous. Irrigation of areas associated with these rocks and deposits can result in concentrations of selenium in water that exceed criteria for the protection of freshwater aquatic life. Geologic and climatic data for the Western United States were evaluated and incorporated into a geographic information system (GIS) to produce a map identifying areas susceptible to irrigation-induced selenium contamination. Land is considered susceptible where a geologic source of selenium is in or near the area and where the evaporation rate is more than 2.5 times the precipitation rate. In the Western United States, about 160,000 square miles of land, which includes about 4,100 square miles (2.6 million acres) of land irrigated for agriculture, has been identified as being susceptible. Biological data were used to evaluate the reliability of the map. In 12 of DOI's 26 study areas, concentrations of selenium measured in bird eggs were elevated sufficiently to significantly reduce hatchability of the eggs. The GIS map identifies 9 of those 12 areas. Deformed bird embryos having classic symptoms of selenium toxicosis were found in four of the study areas, and the map identifies all four as susceptible to irrigation-induced selenium contamination. The report describes the geography, geology, and ground-water resources of the Dutch Flats area in Scotts Bluff and Sioux Counties, Nebr. The area comprises about 60 square miles and consists predominantly of relatively flat-lying terraces. Farming is the principal occupation in the area. The farm lands are irrigated largely from surface water; ground water is used only as a supplementary supply during drought periods. The climate in the area is semiarid, and the mean annual precipitation is about 16 inches. The rocks exposed in the Dutch Flats area are of Tertiary sad Quaternary age. A map showing the areas of outcrop of the rock formations is included in the report. Sufficient unconfined ground water for irrigation supplies is contained in the deposits of the .third terrace, and wells that yield 1,000 to 2,000 gallons a minute probably could be developed. The depth to water in the area ranges from a few feet to about 80 feet sad averages about 30 feet. The depth to water varies throughout the year; it is least in the late summer when the recharge from irrigation is greatest, sad it is greatest in the early spring before irrigation is begun. A map showing the depth to water in September 1949 is included in the report. The ground-water reservoir is recharged by seepage from irrigation canals and laterals, by seepage from irrigation water applied to the farms, and, to a much lesser extent, by precipitation. In the area b

Babcock, H. M.; Visher, F. N.; Durum, W. H.

1951-01-01

170

Contributions to the three-dimensional vortex element method and spinning bluff body flows  

NASA Astrophysics Data System (ADS)

Several contributions to the three-dimensional vortex element method for incompressible flows are presented. We introduce redistribution schemes based on the hexagonal lattice in two dimensions, and the face-centered cubic lattice in three dimensions. Interpolation properties are studied in the frequency domain and are used to build highorder schemes that are more compact and isotropic than equivalent cubic schemes. We investigate the reconnection of vortex rings at small Reynolds numbers for a variety of configurations. In particular, we trace their dissipative nature to the formation of secondary structures. A method for flows with moving boundaries is implemented. The contributions of rotating or deforming boundaries to the Biot-Savart law are derived in terms of surface integrals. They are implemented for rigid boundaries in a fast multipole algorithm. Near-wall vorticity is discretized with attached panels. The shape function and Biot-Savart contributions of these elements account for the presence of the boundary and its curvature. A conservative strength exchange scheme was designed to compute the viscous flux from these panels to free elements. The flow past a spinning sphere is studied for a Reynolds number of 300 and a wall velocity that is equal to half the free-stream velocity. Three directions of the angular velocity are considered. Good agreement with previous numerical and experimental measurements of the force coefficients is observed. Topological features such as the separation and critical points are investigated and compared amongst the configurations. Finally, preliminary results for flapping motions are presented. Simple rigid geometries are used to model a fish swimming in a free-stream and a flapping plate.

Chatelain, Philippe

171

Record of Decision on Final Environmental Impact Statement for Fish Passage Improvement Project at the Red Bluff Diversion Dam, Central Valley Project, California Mid-Pacific Region. Managing Water in the West.  

National Technical Information Service (NTIS)

The Red Bluff Diversion Dam (RBDD) is part ofthe Central Valley Project's Sacramento Canals Unit, authorized in 1950. In addition to the RBDD, unit facilities include Funks Dam, the Coming pumping plant, the Tehama-Colusa (TC) Canal, and the Coming Canal....

2008-01-01

172

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. Annual report, December 1, 1992--December 31, 1993  

SciTech Connect

The shallow Cretaceous sands of the Schrader Bluff Reservoir occur between depths of 4,000 and 4,800 feet below surface and are estimated to contain up to 1.5 billion barrels of oil in place. The field is currently under production by primary depletion. Initial production indicated that primary recovery will fall short of earlier estimates and waterflooding will have to be employed much earlier than expected. A large portion of the oil-in-place thus would still be left behind in this reservoir after primary and secondary recovery methods have been applied. Enhanced oil recovery (EOR) techniques will be needed to recover the additional portion of remaining oil in this huge reservoir and to add significant additional reserves. Slim tube displacement studies, PVT data and asphaltene precipitation studies are needed for Schrader Bluff heavy oil to define possible hydrocarbon solvent suitable for miscible solvent slug displacement process. Such studies are essential because the API gravity of the crude in Schrader Bluff reservoir varies significantly from well to well. Coreflood experiments are also needed to determine effect of solvent slug size, WAG ratio and solvent composition on the oil recovery and solvent breakthrough. A compositional reservoir simulation study will be conducted later to evaluate the complete performance of the hydrocarbon solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This report contains the following: reservoir description; slim tube displacement studies; and coreflood experiments.

Sharma, G.D.

1994-01-01

173

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. Annual report, January 1, 1994December 31, 1994  

Microsoft Academic Search

Alaska is the second largest oil producing state in the nation and currently contributes nearly 24% of the nations oil production. It is imperative that Alaskan heavy oil fields be brought into production. Schrader Bluff reservoir, located in the Milne Point Unit, which is part of the heavy oil field known as West Sak is estimated to contain 1.5 billion

1995-01-01

174

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

USGS Publications Warehouse

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)

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

1985-01-01

175

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. Annual report, January 1, 1994--December 31, 1994  

SciTech Connect

Alaska is the second largest oil producing state in the nation and currently contributes nearly 24% of the nations oil production. It is imperative that Alaskan heavy oil fields be brought into production. Schrader Bluff reservoir, located in the Milne Point Unit, which is part of the heavy oil field known as West Sak is estimated to contain 1.5 billion barrels of (14 to 21 degree API) oil-in-place. The field is currently under production by primary depletion. The eventual implementation of enhanced oil recovery (EOR) techniques will be vital for the recovery of additional oil from this reservoir. The availability of hydrocarbon gases (solvents) on the Alaska North Slope make the hydrocarbon miscible solvent injection process an important consideration for the EOR project in Schrader Bluff reservoir. Since Schrader Bluff oil is heavy and viscous, a water-alternating-gas (WAG) type of process for oil recovery is appropriate since such a process tends to derive synergetic benefits from both water injection (which provides mobility control and improvement in sweep efficiency) and miscible gas injection (which provides improved displacement efficiency). A miscible solvent slug injection process rather than continuous solvent injection is considered appropriate. Slim tube displacement studies, PVT data and asphaltene precipitation studies are needed for Schrader bluff heavy oil to define possible hydrocarbon solvent suitable for miscible solvent slug displacement process. Coreflood experiments are also needed to determine the effect of solvent slug size, WAG ratio and solvent composition on the recovery and solvent breakthrough. A compositional reservoir simulation study will be conducted later to evaluate the complete performance of the hydrocarbon solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir.

Sharma, G.D.

1995-07-01

176

The Knowledge Bluff  

ERIC Educational Resources Information Center

|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…

Vanderburg, Willem H.

2007-01-01

177

Galloping of Bluff Bodies.  

National Technical Information Service (NTIS)

Six slender square section cylinders, each with different corner radii, were investigated statically and dynamically in smooth and turbulent flows. By progressively rounding off the four corners of a square section, the drag force is reduced substantially...

W. C. Cheung W. C. Man

1982-01-01

178

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. [Quarterly] report, January 1, 1993--March 31, 1993  

SciTech Connect

The ultimate objective of this three-year research project is to evaluate the performance of the hydrocarbon miscible solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This will be accomplished through measurement of PVT and fluid properties of Schrader Bluff oil, determination of phase behavior of Schrader Bluff oil solvent mixtures, asphaltene precipitation tests, slim tube displacement tests, core flood experiments and reservoir simulation studies. The expected results from this project include: determination of optimum hydrocarbon solvent composition suitable for hydrocarbon miscible solvent slug displacement process, optimum slug sizes of solvent needed, solvent recovery factor, solvent requirements, extent and timing of solvent recycle, displacement and sweep efficiency to be achieved and oil recovery. Work performed during quarter includes preliminary reservoir fluid characterization and multiple contact test runs using equation-of-state (EOS) simulator. Reservoir fluid samples are being acquired from Conoco Inc., and the process is expected to continue through the next quarter. Also, the experimental apparatus for the displacement study was set up.

Sharma, G.D.

1993-06-01

179

Study of hydrocarbon miscible solvent slug injection process for improved recovery of heavy oil from Schrader Bluff Pool, Milne Point Unit, Alaska. [Quarterly] report, January 1, 1994--March 31, 1994  

SciTech Connect

The ultimate objective of this three-year research project is to evaluate the performance of the hydrocarbon miscible solvent slug process and to assess the feasibility of this process for improving recovery of heavy oil from Schrader Bluff reservoir. This will be accomplished through measurement of PVT and fluid properties of Schrader Bluff oil, determination of phase behavior of Schrader Bluff oil solvent mixtures, asphaltene precipitation tests, slim tube displacement tests, core flood experiments and reservoir simulation studies. The expected results from this project include: determination of optimum hydrocarbon solvent composition suitable for hydrocarbon miscible solvent slug displacement process, optimum slug sizes of solvent needed, solvent recovery factor, solvent requirements, extent and timing of solvent recycle, displacement and sweep efficiency to be achieved and oil recovery. During this quarter, more displacement experiments in slim tube and miscible coreflood experiments have been conducted. Also, work has been initiated to match the slim tube displacement results using GEM, a compositional simulator developed by Computer Modelling Group.

Sharma, G.D.

1994-06-01

180

Health assessment for Mid-America Tanning Company, Sergeant Bluff, Woodbury County, Iowa, Region 7. CERCLIS No. IAD085824688. Preliminary report  

SciTech Connect

The Mid-America Tanning Company (MAT) Site is proposed to be listed by the U.S. Environmental Protection Agency (EPA) on the National Priorities List (NPL). Mid-America Tanning, now U.S. Tanning, is an animal hide processing plant located on 98.7 acres approximately five miles south of Sergeant Bluff, Woodbury County, Iowa. From June 1978 to the present, use of chromium has been extended to the entire process, which involves the treatment of approximately 1000 hides per day. The process utilizes trivalent chromium and produces waste sludge and liquids that are treated on-site at the company wastewater treatment facility. Based on the available information, this site is considered to be of potential public health concern because of the risk to human health caused by the likelihood of exposure to hazardous substances via groundwater, surface water and soil. Further environmental characterization and sampling of the site and impacted off-site areas during the Remedial Investigation and Feasibility Study (RI/FS) should be conducted to address the environmental and human exposure pathways discussed above and to further define the extent of contamination at the site.

Not Available

1990-06-08

181

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

SciTech Connect

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.

Not Available

1991-09-24

182

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

USGS Publications Warehouse

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.

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

2013-01-01

183

Calvert Cliffs refueling pool decontamination; An update  

Microsoft Academic Search

Baltimore Gas and Electric Company described its first experience with the use of Sigma Engineering's WEPA mechanical cleaning equipment for a refueling pool decontamination in the April 1984 issue of Radiation Protection Management. Since the initial refueling pool decontamination at Unit 1 of the Calbert Cliffs Nuclear Power Plant in 1983, three additional refuelings and subsequent refueling pool decontaminations have

B. A. Watson; D. L. Montana

1986-01-01

184

Wake Instabilities Behind Bluff Bodies  

Microsoft Academic Search

\\u000a The observation by Bénard of a vortex street in the wake of a circular cylinder has been commonly associated with the stability\\u000a analysis of the double alternate street proposed by von Kármán. After a short historical review of these studies, we present\\u000a the main progress in understanding this instability during the last decade. New experiments and the control of two-dimensional

Michel Provansal

185

CO2 Sequestration Potential of Texas Low-Rank Coals  

SciTech Connect

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.

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

2006-08-31

186

Ab initio studies of the formation of a Y1-xNi2 superstructure with ordered Y vacancies  

NASA Astrophysics Data System (ADS)

Ab initio total-energy calculations have been performed to study the structural stability of Y1-xNi2. In the literature (Villars P and Calvert L D 1985 Pearson's Handbook of Crystallographic Data for Intermetallic Phases (Materials Park, OH: American Society for Metals)) YNi2 is often considered to show the cubic Laves phase structure, but x-ray diffraction experiments of Latroche et al ( J. Less-Common Met. 161 L27) showed that YNi2 crystallizes in a superstructure of C15 with ordered Y vacancies with a stoichiometry of approximately Y0.95Ni2. The total-energy calculations for the superstructure and for the ideal C15 structure, as well as for the neighbouring phases in the Y-Ni phase diagram YNi and YNi3, confirm that the formation of the superstructure with Y vacancies is favoured against the formation of the pure C15 compound YNi2. The calculated relaxation of the atoms around the vacancies is also in good agreement with the experimental results (Latroche et al), demonstrating that the relaxation of strains in the Y sublattice is the driving mechanism for formation of vacancies. In addition, the electronic properties of the vacancy superstructure have been examined.

Lindbaum, A.; Hafner, J.; Gratz, E.

1999-02-01

187

Palaeoenvironmental Indications of Enhanced Primary Productivity During Pliocene Sapropel Formation  

NASA Astrophysics Data System (ADS)

Cores taken during the Ocean Drilling Program (ODP) Leg 160 in the eastern Mediterranean basin revealed periodic, laminated intervals with high organic contents, i.e. sapropels (Emeis et al., 1996). These include Pliocene sediments showing cyclic variations in organic matter deposition strongly correlated to the precession cyclicity of the Earth's orbit (e.g. Rossignol-Strick, 1985; Lourens et al., 1996a). The two main causes for sapropel formation are either climate-related enhanced organic matter productivity and/or increased preservation due to oxygen depletion of the bottom waters (e.g. Calvert et al., 1992; Canfield, 1994). Increased productivity is suggested to be the driving force in generating euxinic conditions leading to sapropel deposition (e.g. Passier et al., 1999). Photic zone euxinia was most probably triggered by large-scale input of nutrients from the Nile and other rivers leading to enhanced primary productivity and consequently high organic matter fluxes. This was based on concentrations of isorenieratene, a biomarker of photic zone euxinia, studied in three lateral time-equivalent Pliocene sapropels (subm. Menzel et al., 2001). Photic zone euxinia was more pronounced at the central and western part of the eastern Mediterranean basin, when compared with the most eastern part, where a deepening of the chemocline resulted from the increased delivery of fresh water. Using additional biomarkers will provide detailed insights in palaeoenvironmental changes that caused high organic matter deposition. The quantitative analysis of compounds specific for phytoplankton classes, e.g. isololiolides and loliolides reflecting Bacillariophyta, C37 - C39 alkenones indicative of Prymnesiophyta etc., will result in reconstruction of compositions of the standing crop and changes thereof at the time of deposition. The quantitative analysis of long-chain n-alkanes, indicating higher land plants, could reveal river input into the basin. Carbon isotope compositions of these alkanes may provide signatures in vegetation transition between C4/C3 land plants at periods of sapropel and non-sapropel formation. Changes in primary productivity conditions will be investigated using carbon isotope analyses of alkenones, reflecting the fractionation effect during CO2 assimilation. Simultaneously, the Uk'37 of C37 alkenones will be used to reconstruct climate-related sea surface temperature changes in the basin. References: Calvert, S.E. Nielsen, B. and Fontugne, M.R., 1992. Nature, 359: 223-225. Canfield, D.E., 1994. Chem. Geol., 114: 315-329. Emeis, K.C., Robertson, A.H.F., Richter, C. et al., 1996. Proceedings of the Ocean Drilling Program, 160 (initial reports, Mediterranean 1, College Station, TX). Lourens L.J., Antonarakou, A., Hilgen, F.J., van Hoof, A.A.M., Vergnaud-Grazzine, C. and Zachariasse, W.J., 1996a. Palaeoceanography, 11: 391-413. Menzel, D., Hopmans, E.C., van Bergen, P.F., de Leeuw, J.W. and Sinninghe Damste, J.S. subm. 2001. Passier, H.F., Bosch, H.J., Nijenhuis, I.A., Lourens, L.J., Boettcher, M.E., Leenders, A., Sinninghe Damste, J.S., de Lange, G.J. and de Leeuw, J.W., 1999. Nature, 397: 146-149.

Menzel, D.; Hopmans, E. C.; Schouten, S.; van Bergen, P. F.; Sinninghe Damste, J. S.

2001-12-01

188

Concept Formation.  

ERIC Educational Resources Information Center

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…

Vaidya, Narendera

189

Paleomagnetic and rock magnetic evidence for a secondary yet early magnetization in large sandstone pipes and host Late Middle Jurassic (Callovian) Summerville Formation and Bluff Sandstone near Mesita, west central New Mexico  

Microsoft Academic Search

Processes responsible for the acquisition of ancient yet secondary magnetizations are important facets of the geologic history of rocks and, when the age of such magnetizations can be estimated with confidence, provide useful information on the ancient geomagnetic field. In west central New Mexico near Mesita, on the Colorado Plateau, hematitic sandstone and siltstone beds of the Middle Jurassic (Callovian)

John W. Geissman; Stephen S. Harlan

2004-01-01

190

PREFERENCE FORMATION  

Microsoft Academic Search

? Abstract This review concerns political preferences—what they are and where they come from. We begin by documenting the close relationship between processes of preference formation and change. Rather than suddenly appearing, most preferences emerge from interactions between individuals and their environment. This aspect of preference formation poses a concrete challenge: to uncover the mechanics of these interactions in important

James N. Druckman; Arthur Lupia

2000-01-01

191

Formation fracturing  

Microsoft Academic Search

A fracturing process is described in which a fracture formed in a formation is acid etched near the well and particle propped in the more remote portions of the fracture. A fracture is formed in the formation extending from the well and an acidizing fluid is injected into the fracture, in order to acid etch the walls thereof adjacent to

J. L. Fitch; T. C. Jr. Vogt

1972-01-01

192

Star Formation During Galaxy Formation  

NASA Astrophysics Data System (ADS)

Young galaxies are clumpy, gas-rich, and highly turbulent. Star formation appears to occur by gravitational instabilities in galactic disks. The high dispersion makes the clumps massive and the disks thick. The star formation rate should be comparable to the gas accretion rate of the whole galaxy, because star formation is usually rapid and the gas would be depleted quickly otherwise. The empirical laws for star formation found locally hold at redshifts around 2, although the molecular gas consumption time appears to be smaller, and mergers appear to form stars with a slightly higher efficiency than the majority of disk galaxies.

Elmegreen, B. G.

2011-11-01

193

CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS  

SciTech Connect

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.

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

2004-11-01

194

Planet formation  

Microsoft Academic Search

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

Jack J. Lissauer

1993-01-01

195

Planet Formation  

NASA Astrophysics Data System (ADS)

1. Historical notes on planet formation Bodenheimer; 2. The formation and evolution of planetary systems Bouwman et al.; 3. Destruction of protoplanetary disks by photoevaporation Richling, Hollenbach and Yorke; 4. Turbulence in protoplanetary accretion disks Klahr, Rozyczka, Dziourkevitch, Wunsch and Johansen; 5. The origin of solids in the early solar system Trieloff and Palme; 6. Experiments on planetesimal formation Wurm and Blum; 7. Dust coagulation in protoplanetary disks Henning, Dullemond, Wolf and Dominik; 8. The accretion of giant planet cores Thommes and Duncan; 9. Planetary transits: direct vision of extrasolar planets Lecavelier des Etangs and Vidal-Madjar; 10. The core accretion - gas capture model Hubickyj; 11. Properties of exoplanets Marcy, Fischer, Butler and Vogt; 12. Giant planet formation: theories meet observations Boss; 13. From hot Jupiters to hot Neptures … and below Lovis, Mayor and Udry; 14. Disk-planet interaction and migration Masset and Kley; 15. The Brown Dwarf - planet relation Bate; 16. From astronomy to astrobiology Brandner; 17. Overview and prospective Lin.

Klahr, Hubert; Brandner, Wolfgang

2011-02-01

196

Galaxy formation  

PubMed Central

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.

Peebles, P. J. E.

1998-01-01

197

Planet Formation  

Microsoft Academic Search

Motivating the study of planet formation is not difficult for any curious audience. One of the fundamental human questions\\u000a is that of origins: “where did I come from?„. Breaking this down into constituents produces a series of questions. How did\\u000a the Universe begin? How did stars form? How did planets form? How did life begin? How did intelligent life develop?

Thomas Quinn

2005-01-01

198

Dune Formation  

Microsoft Academic Search

Dunes are ubiquitous and exist in many forms in deserts and along coasts. They are a consequence of the wind moving sand grains\\u000a by a mechanism called “saltation”. In order to describe the formation and evolution of dunes one must understand the surface\\u000a flux of sand. Using the equation of motion of turbulent air in the approximation of Jackson and

Hans J. Herrmann

199

Cloud Formation  

NASA Astrophysics Data System (ADS)

Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic.1 In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, ``The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894.''3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

Graham, Mark Talmage

2004-05-01

200

CO2 Sequestration Potential of Texas Low-Rank Coals  

SciTech Connect

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.

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

2006-07-01

201

Prescribed Burn at Pine Bluff Arsenal.  

National Technical Information Service (NTIS)

Fire is an important ecological process in the southern United States. Many animal and plant species evolved in the presence of fire, and many vegetation types thrive best in the presence of fire. Fire-dependent biota are declining, because of fire suppre...

L. Peacock M. Melnechuk

2003-01-01

202

Oak Bluffs Town Beach, Martha's Vineyard, Massachusetts.  

National Technical Information Service (NTIS)

The project consists of the restoration and protection of approximately 1200 feet of public beach at Ocean Beach Park, Dukes County, Massachusetts. Beach raising, widening and groin construction will correct natural deterioration currently taking place. T...

1971-01-01

203

Identifying Fossils: Exploring the Mississippi River Bluffs  

NSDL National Science Digital Library

This activity is a geology lab where students learn about fossils found in sedimentary rocks and show their understanding by writing a literary nonfiction paper from the perspective of one of those fossils.

204

Water-Quality Data, 1999-2005, and Ground-Water Level Data, 2004-2005, for McBaine Bottoms, Including the Eagle Bluffs Conservation Area, Columbia, Missouri  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the city of Columbia, Missouri, and the Missouri Department of Conservation, collected ground-water quality data from June 1999 through August 2005, surface-water quality data from August 1999 through August 2003, and water-level data from February 2004 through August 2005 in McBaine Bottoms, southwest of Columbia. McBaine Bottoms, adjacent to the Missouri River, is the location of the municipal-supply well field for the city of Columbia, the city of Columbia wastewater-treatment wetlands, and the Missouri Department of Conservation Eagle Bluffs Conservation Area. This report presents water-quality data, which include water-quality analyses of samples collected from 36 water-quality sampling sites (31 were wells and 5 were surface-water sites), and ground-water level data, which include water-level measurements from more than 80 wells. Water samples were analyzed for physical properties, inorganic chemical constituents, nutrients, and dissolved iron. Selected samples were analyzed for trace elements, wastewater organic compounds, and pesticides. In samples from monitoring wells, chloride concentrations ranged from 2.41 to 259 mg/L (milligrams per liter), sodium concentrations ranged from 1.08 to 175 mg/L, and sulfate concentrations ranged from less than 0.2 to 271 mg/L (all concentrations were dissolved). Dissolved nitrite plus nitrate as nitrogen concentrations ranged from less than 0.05 to 0.46 mg/L. Total phosphorous concentrations ranged from less than 0.04 to 1.68 mg/L, dissolved phosphorous concentrations ranged from less than 0.04 to 1.50 mg/L, and dissolved orthophosphorous concentrations ranged from less than 0.01 to 1.83 mg/L. Dissolved iron concentrations ranged from less than 6 to 42,900 g/L (micrograms per liter). Dissolved arsenic concentrations in samples from two monitoring wells ranged from 11 to 37 g/L. In samples from surface-water sampling sites, chloride concentrations ranged from 8.67 to 289 mg/L, sodium concentrations ranged from 6.18 to 219 mg/L, and sulfate concentrations ranged from 33.4 to 119 mg/L. All of the minimum concentrations were detected in samples from Perche Creek. Dissolved nitrite plus nitrate as nitrogen concentrations ranged from less than 0.05 to 1.53 mg/L. Total phosphorous concentrations ranged from 0.07 to 3.06 mg/L, dissolved phosphorous concentrations ranged from less than 0.05 to 2.88 mg/L, and dissolved orthophosphorous concentrations ranged from less than 0.01 to 2.86 mg/L. Most of the maximum concentrations were detected in samples from the city outflow. More than 35 wastewater organic compounds and pesticides were detected in samples from the city outflow. However, most concentrations were estimated or their presence verified, but not quantified. Water levels in monitoring wells ranged from 548.54 to 576.55 ft (feet) above the National Geodetic Vertical Datum of 1929 (NGVD 29). The difference in water levels from February 2004 to August 2005 ranged from 0.13 ft to 10.97 ft.

Smith, Brenda J.; Richards, Joseph M.

2006-01-01

205

Galaxy formation  

NASA Astrophysics Data System (ADS)

This is an introductory lecture to the problem of Galaxy Formation. A general background in Cosmology, containing basic notions that enter in this problem, is briefly presented in the introduction. Section 2 deals with the properties of density perturbations. The emphasis is given on describing the role of the power spectrum of density perturbations in constructing the typical mass fluctuations of various mass scales. The evolution of a density peak in the post recombination era is examined up to the point where this evolution can be given by analytical formulae (linear phase). These formulae are very useful in understanding the role and the significance of various quantities in the problem of galaxy formation. The evolution of density fluctuations in the non-linear phase can be followed by N-Body simulations. This requires a careful preparation of initial conditions for the N-Body runs, consistent with a given power spectrum, that is discussed. In section 3 the problem of angular momentum transfer to protogalaxies is discussed in connection with the behavior of the cosmological tidal torques. The difficulties of simulating this behavior are explained. Counterrotating objects may result from the behavior of the cosmological tidal torque combined with the incomplete mixing of the material after the collapse. In section 4 the main properties of objects resulting from dissipationless collapse are compared with the observational laws of galaxies. An insight is given into the mechanism of redistribution of energies during violent relaxation, and its consequences on the collapse factors of various shells. The collapse factors in the inner parts of these objects can be considerably larger than those predicted by the virial theorem. The role of dissipation is examined in section 5. Dimensional analysis allows to define various loci on the plane of virial density versus virial temperature. The formation of a disk supported by rotation is also discussed.

Voglis, Nikos

206

A model for heavy mineral deposit formation within Pleistocene to Holocene shoreline sequences in Georgia  

SciTech Connect

The forms and locations of heavy mineral (HM) deposits, and the geomorphologies and HM suites of the six major Pleistocene paleobarrier island complexes on the Georgia coastal plain and the Holocene shoreline deposits may be the result of physical conditions prevalent during the development of two distinct shoreline sequences. The older Wicomico, Penholoway and Talbot complexes are typified by large, linear, undissected sand bodies and long, linear HM deposits and may have been strongly influenced by a greater sediment supply, a wave-dominated energy regime, and a steeper continental shelf than the younger Pamlico, Princess Anne, Silver Bluff and Holocene complexes. The younger complexes which consist of small, stubby and complexly dissected sand bodies may be the result of a tidal dominated energy regime and a more restricted sediment source. In the younger complexes, HM deposits are short and stubby and are commonly located immediately south of a source river. These relations indicate that only a relatively minor amount of longshore transport has occurred. Location of the HM deposits in the older shoreline sequences at a considerably greater distance south of a source river indicates that a greater degree of transport was involved. The development of stronger and more consistent longshore currents and winds during the earlier part of the Pleistocene may account for the differences in sediment transport and HM deposit formation in the older shoreline sequences. These physical differences may be related to the steeper continental shelf and different climatic conditions during the warmer, interglacial period.

Cocker, M.D. (Georgia Geologic Survey, Atlanta, GA (United States))

1993-03-01

207

ANTIBODY FORMATION  

PubMed Central

Injection of a small bacteriophage ?X 174 into guinea pigs results in an accelerated elimination of phage detectable as early as 24 hours after injection. The immune nature of the accelerated elimination is indicated by its specificity, by the appearance of excess specific serum antibody after phage elimination, and by the prevention of accelerated elimination by 400 r whole body x-irradiation of guinea pigs prior to injection of phage. The early antibody response is considered to be a primary one since an analogous response occurs in newborn guinea pigs, antibody is not detectable in the sera of non-immunized animals, and the second challenge with ?X stimulates a serum antibody response 100-fold greater than that after primary immunization. The early detection of immune elimination appears to be due, in part, to the small amounts of phage employed, since larger doses of phage delay the time of onset of detectable immune elimination. The early rise of serum antibody in the primary and secondary response appears exponential with a similar rate constant of antibody formation. The rate constant is also independent of dose. These findings have led to the suggestion that during this exponential phase, the relative rate of antibody formation at a cellular level may be constant for a given antigen.

Uhr, Jonathan W.; Finkelstein, Martin S.; Baumann, Joyce B.

1962-01-01

208

Calvert versus Carroll: The Quitrent Controversy between Maryland's Founding Families  

Microsoft Academic Search

This essay examines the historical background behind the 1826 U.S. Supreme Court case of Cassell v. Carroll. The legal merits in the case concerned arcane questions of feudal property law which the Court avoided and left unanswered. Today the case is of little jurisprudential significance. It is the historical record behind Cassell v. Carroll that tells a story that continues

Garrett Power

2005-01-01

209

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

...cooling systems for light- water nuclear power reactors,'' requires, among...boiling or pressurized light-water nuclear power reactor fueled with uranium oxide...law, will not present an undue risk to public health or safety,...

2011-01-25

210

Bimodal Star Formation, Starbursts, and Galaxy Formation  

Microsoft Academic Search

A phenomenological approach is developed for studying star formation in the galactic disk, in starbursts, and in protogalaxies. The evidence is reviewed for bimodal star formation, and physical mechanisms are mentioned. A simple expression for the star formation rate in the disk is derived, and applied to estimate star formation time scales in the disk, in starbursts, and in protogalaxies.

Joseph Silk

1988-01-01

211

Formate ester formation in amide solutions  

NASA Astrophysics Data System (ADS)

Simple aliphatic alcohols, deoxynucleosides and nucleosides undergo reaction with formamide yielding formate esters. Formate ester formation was observed to occur slowly at 100°C and more rapidly at 130°C. As expected, formate esters were hydrolyzed to the alcohol and formic acid upon heating in aqueous solution. It was proposed to study the possibility that formate esters are formed initially in amide solvents, followed by displacement of formate by dihydrogen phosphate ion to form monophosphate esters. Experiments are described which demonstrate the formation and hydrolysis of formate esters, as well as their lack of reaction with hydrogen phosphate ion. Formate esters are not intermediates in the phosphorylation of nucleosides in formamide. Their formation has been observed and such an esterification is a side reaction during the phosphorylation of nucleosides in formamide.

Schoffstall, Allen M.; Mahone, Saralyn M.

1988-12-01

212

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

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

213

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

NASA Astrophysics Data System (ADS)

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.

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

214

Star formation in disks  

Microsoft Academic Search

It is noted that the principal characteristics of the stellar populations in galaxies depend on the history of star formation and the initial mass spectrum with which the stars are formed. Whereas there have been a number of attempts to model the history of star formation in galaxies using various quasi-theoretical descriptions of star formation, star formation remains poorly understood

R. B. Larson

1983-01-01

215

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

SciTech Connect

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.

Tull, J.F. (Florida State Univ., Tallahassee, FL (United States). Dept. of Geology)

1993-03-01

216

Formate Formation and Formate Conversion in Biological Fuels Production  

PubMed Central

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.

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

2011-01-01

217

Formate formation and formate conversion in biological fuels production.  

PubMed

Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO(2) 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 CO(2) in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO(2) and H(2) 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

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

2011-05-24

218

Star Formation in Galaxies  

NASA Astrophysics Data System (ADS)

The process of star formation is at the core of the evolutionary cycle of galaxies, as newborn stars produce new chemical elements, dust, and light. The energetic output delivered first by stellar winds and then by supernovae a few Myr after a star formation episode may also directly impact on the evolution of galaxies and their interstellar medium (ISM), as well as having an effect on the intergalactic medium (IGM), through feedback and outflows.This chapter concerns star formation on galactic scales. First, the galactic processes that may affect large-scale star formation are presented. Second, the various methods to measure star formation rates are discussed (star formation tracers, timescales, calibrations, limits). Finally, the observational status concerning star formation in galaxies (its relation to other quantities and its evolution) is presented. The Schmidt Law (star formation rate-gas relationship) is amply discussed.

Boissier, Samuel

219

Star Formation in Galaxies  

Microsoft Academic Search

Star formation on a galactic scale is regulated by the self-gravity of the gas, as shown by the Jeans-length spacing of giant cloud complexes along spiral arms and the sensitivity of the star formation rate to the gravitational stability parameter Q. Simple models based on this scenario reproduce the general properties of galactic star formation in both normal and starburst

B. G. Elmegreen

1999-01-01

220

Theory of Star Formation  

Microsoft Academic Search

We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions. The key dynamical processes involved in star formation---turbulence, magnetic

Christopher F. McKee; Eve C. Ostriker

2007-01-01

221

NRL Report Formats.  

National Technical Information Service (NTIS)

This NRL Report Formats publication has been extracted from the Format and Style Guide to provide authors and those who prepare reports a concise reference guide to technical report formats. This publication is organized in the same way as an NRL Report, ...

T. D. Calderwood

1993-01-01

222

Autonomous formation flight  

Microsoft Academic Search

This article describes an approach to close-formation flight of autonomous aircraft. A standard LQ-based structure was synthesized for each vehicle and for formation position error control using linearized equations of motion and a lifting line model of the aircraft wake. We also consider the definition of a formation management structure, capable of dealing with a variety of generic transmission and

F. Giulietti; L. Pollini; M. Innocenti

2000-01-01

223

Tropical cyclone formation  

SciTech Connect

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.

Montgomery, M.T.; Farrell, B.F. (Harvard Univ., Cambridge, MA (United States))

1993-01-15

224

Impulsively Triggered Star Formation  

Microsoft Academic Search

I review several different modes of impulsively triggered star formation, starting with star formation in turbulent molecular\\u000a clouds, and exploring the origin of the clump mass function and the scaling relations between clump mass, radius and internal\\u000a velocity dispersion. This leads to the identification of a critical ram pres-sure for triggering rapid star formation, and\\u000a a reappraisal of the minimum

A. P. Whitworth

2003-01-01

225

Homeownership and family formation  

Microsoft Academic Search

In Western countries, home-ownership and family formation are closely connected. From most research on the transition to home-ownership, one gets the impression that the association between family formation and home-ownership is positive: family formation seems to speed up the process of acquiring a home in several countries. However, it has also been argued that there might be a negative association

Clara H. Mulder

2006-01-01

226

Data format translation routines  

SciTech Connect

To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base.

Burris, R.D.

1981-02-01

227

Flash Open File Format  

NSDL National Science Digital Library

Macromedia has released the file format specification for its Flash (discussed in the April 11, 1997 Scout Report) multimedia web tool. Flash allows web developers to create vector based graphics and animation. By making the format (.swf) available, Macromedia hopes to establish it as a standard for vector graphics and animation. The company claims it will "submit the format specification to a recognized Internet standards organization." In addition to providing the file format specification, the site provides Flash related news releases, a Flash FAQ, and a vector graphics white paper.

228

Three Dimensional Formation Flight Control.  

National Technical Information Service (NTIS)

Automating the control of an aircraft flying in formation necessitates the extension of the theory of formation flight control to allow for three dimensional maneuvers. The formation was modeled as a two-aircraft, leader and wingspan, formation. Both airc...

J. K. Hall

2000-01-01

229

Global Star Formation Revisited  

NASA Astrophysics Data System (ADS)

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.

Silk, Joseph; Norman, Colin

2009-07-01

230

Biomarker variations in relation to paleogeography in the Saltos Shale member of the Monterey Formation, Cuyama basin, California  

SciTech Connect

The Miocene stratigraphy of the Cuyama basin provides an excellent opportunity to correlate geology with molecular organic geochemistry (e.g., biomartker compounds) because the paleogeography and paleobathymetry of the basin are well constrained by surface and subsurface geologic mapping and detailed micropaleontology. The Monterey Formation is composed of biogenous and terrigenous sediments that accumulated in a deep marine borderland basin adjacent to a Miocene shoreline. the lower member, the Saltos Shale, is predominately terrigenous sediment interbedded with impure carbonates that consist of foraminifera and calcareous nannofossils. The upper member, the Whiterock Bluff Shale, is composed of highly biogenous (siliceous and carbonate) sediments. The biomarker composition of the Saltos Shale is dependent on the relative contributions of planktonic and benthonic organisms, bacteria, and terrigenous organic matter transported from the nearby landmass. A general trend in biomarker distribution is observed in relation to paleogeography (i.e. proximity to shoreline). Pristane/phytane ratios, hopane/sterane ratios, oleanane/hopane ratios, and diasterane/sterane ratios are higher near the shoreline (to the east) because of increased terrigenous input. The more distal western basin sediments contain biomarkers that were predominately derived from marine phytoplankton and bacteria. Submarine fan sediments in the Saltos Shale were deposited in the eastern basin east of the penecontemporaneous Cox fault. Ponding of terrigenous organic matter at the base of slope is reflected by high ratios of pristane/phytane (2.7), oleanane/hopane (0.79), C{sub 29}/C{sub 27} {alpha}{alpha}{alpha}2OR steranes (1.56), and relatively large amounts of waxy n-alkanes (C{sub 27}, C{sub 29}, C{sub 31}). In contrast, the prefan and postfan sediments contain lower concentrations of these terrigenous biomarkers.

Lillis, P.G. (Geological Survey, Denver, CO (USA))

1990-05-01

231

Formative Assessment Probes  

ERIC Educational Resources Information Center

|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…

Eberle, Francis; Keeley, Page

2008-01-01

232

Extendable Information Formats.  

National Technical Information Service (NTIS)

Information formats can often be adapted for use by processes different than those for which they were initially designed. The extent to which a format can be so adapted without semantic modification is a measure of its extendability. There are many infor...

J. E. Donnelley

1976-01-01

233

Theories of star formation  

Microsoft Academic Search

A well defined theory of star formation does not yet exist. A serious deficiency therefore remains in current theories of the structure and evolution of stars. Since stars must be forming at the present phase of Galactic evolution, it is pertinent to investigate what conditions favour star formation. Observational evidence for the pre-main sequence phase of stellar evolution is entirely

D. McNally

1971-01-01

234

Subsurface formation fracturing method  

Microsoft Academic Search

In this fracturing method, the well is first prepared for fracturing by cutting the casing and notching the formation at the desired level in the well. Fracturing fluid is then applied at the notch under sufficient pressure to initiate a fracture in the formation. During propagation of the fracture, fracturing fluid containing propping agent is pumped into the fracture in

J. L. Huitt; B. B. McGlothlin; J. Papaila

1965-01-01

235

Formate production through biocatalysis.  

PubMed

The generation of formate from CO 2 provides a method for sequestration of this greenhouse gas as well as the production of a valuable commodity chemical and stabilized form of hydrogen fuel. Formate dehydrogenases are enzymes with the potential to catalyze this reaction; however they generally favor the reverse process, i.e., formate oxidation. By contrast, the formate dehydrogenase of the acetogen Clostridium carboxidivorans has been found to preferentially catalyze the reduction of CO 2. This is in accord with its natural role to introduce CO 2 as a carbon source in the Wood-Ljungdahl pathway. The direction of catalysis derives from the enzyme's low affinity for formate. This enzyme is therefore an excellent candidate for biotechnological applications aimed at producing formic acid and derivative chemicals from CO 2. PMID:23841981

Alissandratos, Apostolos; Kim, Hye-Kyung; Easton, Christopher J

2013-06-21

236

Formation of the Carolina Bays: ET Impact vs. Wind-and-Water  

NASA Astrophysics Data System (ADS)

The Carolina Bays are a group of lakes, wetlands, and depressions, stretching from Florida to New Jersey along the Atlantic Ocean, and ranging up to 11 km in length and about 15 m in depth. Their distinctive elliptical shapes and common orientation towards the Great Lakes region have generated many hypotheses about their method of formation, including extraterrestrial impact (Melton and Schriever, 1933; Prouty, 1934). Another suggests that springs or groundwater dissolution of soluble minerals caused subsidence, which formed water-filled depressions that became the Bays (Johnson, D.W., 1944). One of the prevailing views is that Carolina Bays represent irregular lakes that were gradually reshaped into ellipses by circulating lake currents, generated by strong ice-age winds blowing perpendicular to the current long axes of the Bays (Kaczorowski, 1977). We report results from a suite of cores taken from within a Bay, which we have named "Howard Bay," located about 2 km north of the town of Duart in Bladen County, North Carolina. Located on the high western bluff of the Cape Fear River, the Bay is 2.7 km long, 1.6 km wide, and filled with about 9 meters of sediment with an encircling rim that is ~1-meter high. Analyses of seven cores along the long axis of Howard Bay reveal an assemblage of abundant magnetic grains, microspherules, carbon spherules, glass-like carbon, and iridium, typical of the YDB impact layer (12.9 ka) at many other sites across North America. The impact layer conforms to the basal contours of the basin, suggesting that the markers were deposited immediately or soon after the Bay formed. Further analyses of samples in complete core sequences reveal that, unlike typical, peat-rich Carolina Bays, Howard Bay essentially lacks peat, diatoms, pollen, or other organic materials, suggesting that this Bay never stored water for any sustained length of time. Furthermore, several trenches confirm that the deepest part of the Bay is filled with >6 m of cross-bedded eolian sand with no evidence of lacustrine sedimentation. This evidence calls into question prevailing hypotheses (a) that all Bays were lakes and ponds in the past and that their shapes were formed by wave action, or (b) that groundwater movement led to subsidence that formed the Bay. The presence of impact markers, including high concentrations of iridium, in a layer just above the basal sediments of this Bay that is filled with eolian sand supports the extraterrestrial impact hypothesis for Bay formation.

Kobres, R.; Howard, G. A.; West, A.; Firestone, R. B.; Kennett, J. P.; Kimbel, D.; Newell, W.

2007-05-01

237

When Efficient Star Formation Drives Cluster Formation  

NASA Astrophysics Data System (ADS)

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.

Parmentier, G.; Fritze, U.

2009-01-01

238

Format Monopolies: The Evolution of “Nationwide Format Oligopolies”  

Microsoft Academic Search

Almost ten years after the Telecommunications Act of 1996, 26 different radio station formats in Arbitron's 296 survey areas were examined in 2005 as a followup to Wirth's 2001 “Nationwide Format Oligopolies.” This longitudinal study sought to ascertain if format oligopolies (four companies reaching over 50% of a specific radio format's audience nationally) had evolved into format duopolies (two companies

Todd L. Wirth

2007-01-01

239

Rethinking globular clusters formation  

NASA Astrophysics Data System (ADS)

This paper is aimed at emphasizing some of the main hints, constraints and difficulties we currently have in trying to understand how globular clusters formed, along with their multiple stellar generations, an issue that must be regarded as intimately connected to the formation process itself. Thus, the topics that are addressed include i) the required mass of the progenitor, ii) how to form new stars in an environment already crowded by a previous stellar generation, iii) how photometry and spectroscopy appear to suggest different formation processes for second generation stars, iv) whether dilution with pristine material may (or may not) be necessary for the formation of second generations, v) why the few clusters with multiple iron abundances are after all not so different from those that are homogeneous, and finally vi) why special environmental conditions may not be necessary for the formation of globular clusters with multiple stellar generations.

Renzini, Alvio

240

Understanding Earth: Coal Formation  

NSDL National Science Digital Library

Supplementary material from Understanding Earth (4th ed.), this short animation guides viewers through the formation of coal and its pathway through different grades. The animation is annotated with labels.

W.H. Freeman & Co. Publishing

241

Formatted File Organization Techniques.  

National Technical Information Service (NTIS)

The report contains papers presenting several useful steps toward the creation of a more scientific discipline of formatted file design. In particular, there are papers on: (1) The first extensive, fundamentally oriented comparison of key-to-address trans...

M. E. Senko V. Y. Lum F. P. Palermo S. P. Ghosh P. J. Owens

1970-01-01

242

NRL Report Formats.  

National Technical Information Service (NTIS)

NRL Report Formats was prepared to provide information to those at the Naval Research Laboratory (NRL) who write technical reports and for those who typeset and lay out reports for reproduction. This publication provides easy-to-follow instructions, given...

T. D. Calderwood P. E. Staffieri

1997-01-01

243

What Drives Star Formation?  

Microsoft Academic Search

Current theoretical models for what drives star formation (especially low-mass star formation) are: (1) magnetic support of self-gravitating clouds with ambipolar diffusion removing support in cores and triggering collapse, and (2) compressible turbulence forming self-gravitating clumps that collapse as soon as the turbulent cascade produces insufficient turbulent support. A crucial observational difference between the two models is the mass to

R. M. Crutcher

2003-01-01

244

Plant Formate Dehydrogenase  

SciTech Connect

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.

John Markwell

2005-01-10

245

Formation-flying interferometry  

NASA Astrophysics Data System (ADS)

There are many advantages to space-based interferometry, but monolithic, single-spacecraft platforms set limits on the collecting area and baseline length. These constraints can be overcome by distributing the optical elements of the interferometer over a system of multiple spacecraft flying in precise formation, opening up new realms of angular resolution and sensitivity. While the principles of interferometry are the same as for structurally-connected systems, formation-flying interferometers must integrate a wide range of technologies to provide an optically stable platform capable of finding, tracking and measuring fringes. This paper discusses some of the key differences between formation-flying and structurally-connected interferometers, including formation configurations, controlling beam shear, station-keeping, and the importance of delay and delay rate estimation in determining the instrument sensitivity. Proposed future formation-flying interferometer missions include the Terrestrial Planet Finder (TPF), Darwin, the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), the Stellar Imager, the Micro-Arcsecond Xray Imaging Mission (MAXIM), and its precursor, MAXIM Pathfinder. In addition, Life Finder and Planet Imager have been identified as two formation-flying missions capable of detailed characterization of habitable exo-planets. The parameters for these missions are compared and described briefly.

Lay, Oliver P.; Blackwood, Gary H.

2003-02-01

246

Star formation in irregular galaxies  

Microsoft Academic Search

The problems associated with star formation in irregular galaxies are outlined. The basic model of star formation is reviewed. Global star formation rates, feedback processes, the physical conditions of the interstellar medium which affect star formation, and the internal structures of star-forming regions in irregular galaxies are discussed. In addition, star formation in the amorphous irregular galaxies described by Sandage

D. A. Hunter; J. S. Gallagher III

1989-01-01

247

Urethral seam formation and hypospadias  

Microsoft Academic Search

Knowledge of the formation of the normal male urethra may elucidate the etiology of hypospadias. We describe urethral formation in the mouse, show the similarities and relevance to human urethral development, and introduce the concept of the epithelial seam formation and remodeling during urethral formation. Three mechanisms may account for epithelial seam formation: (1) epithelial-mesenchymal transformation similar to that described

Laurence S. Baskin; Ali Erol; Priya Jegatheesan; Yingwu Li; Wenhui Liu; Gerald R. Cunha

2001-01-01

248

CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS  

SciTech Connect

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.

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

2004-02-01

249

CO2 Sequestration Potential of Texas Low-Rank Coals  

SciTech Connect

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.

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

2006-05-01

250

Vascular Lumen Formation  

PubMed Central

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 cell–cell 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.

Lammert, Eckhard; Axnick, Jennifer

2012-01-01

251

Format-Preserving Encryption  

NASA Astrophysics Data System (ADS)

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.

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

252

Primary Radiation Damage Formation  

SciTech Connect

The physical processes that give rise to changes in the microstructure, and the physical and mechanical properties of materials exposed to energetic particles are initiated by essentially elastic collisions between atoms in what has been called an atomic displacement cascade. The formation and evolution of this primary radiation damage mechanism are described to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the primary variables cascade energy and irradiation temperature are discussed, along with a range of secondary factors that can influence damage formation.

Stoller, Roger E [ORNL

2012-01-01

253

Isolating Triggered Star Formation  

SciTech Connect

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.

Barton, Elizabeth J.; Arnold, Jacob A.; /UC, Irvine; Zentner, Andrew R.; /KICP, Chicago /Chicago U., EFI; Bullock, James S.; /UC, Irvine; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

2007-09-12

254

Wotsit's File Format Collection  

NSDL National Science Digital Library

Wotsit's File Format Collection, provided by Paul Oliver, features a very large number of file formats. These include JPEG image files, wave sound files, Rich Text files, and common database and word-processing files such as Paradox and Wordperfect. Documents collected or linked at the site are primarily either original specifications from the creator or an improved version of the original. All of the specifications are very technical and are directed towards programmers. Users can subscribe to a mailing list for notification of site updates.

255

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

Microsoft Academic Search

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

Tull

1993-01-01

256

Art of the Bluff with Weapons of Mass Destruction.  

National Technical Information Service (NTIS)

Like the Cold War years, the world once again finds itself at the crossroads of mass destruction. Dynamic changes in world political polarity, regional power struggles, and the turmoil of ethnic and religious unrest have positioned humanity at the startin...

J. F. Diehl

1997-01-01

257

Bluff Body Flow Simulation Using a Vortex Element Method  

Microsoft Academic Search

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,

Anthony Leonard; Phillippe Chatelain; Michael Rebel

2004-01-01

258

Computing Bluff Body Flows Using Commercial CFD Software  

NASA Astrophysics Data System (ADS)

Commercial CFD codes are increasingly being used to simulate complex engineering flows. Three commercial codes: CFD-ACE v2004, Fluent 6.2.16 and CFX 5.7.1 are examined for their ability to compute the separated flow over a square cylinder. Large Eddy Simulation (LES) results are presented using four SGS models implemented in these commercial codes: the Smagorinsky's model, the dynamic model (Germano et al., 1991), the localized dynamic model (Kim and Menon, 1995) and the WALE model (Nicoud and Ducros, 1999). Global simulation results, time averaged quantities and phase averaged quantities are benchmarked against the experimental results of Lyn and Rodi (Journal of Fluid Mechanics, 1994). All simulations predict the Strouhal number accurately, and simulations employing the dynamic model are excellent in predicting the mean recirculation length and the r.m.s. of the lift coefficient on the cylinder. In terms of flow fluctuations, all simulations over-predict the streamwise component, but under-predict the vertical component. Velocity fluctuations in the wake correlate well with the fluctuation of forces on the cylinder. An examination of the streamlines of the flow indicates that CFD-ACE and Fluent's implementation of the dynamic model offers the best prediction of the vertical displacement of the wake and the size of the shed vortex. Finally, the addition of 10% upwind differencing to the convective terms is also investigated.

Kirpekar, Sujit

2005-11-01

259

Bluff Body Flow Simulation Using a Vortex Element Method  

SciTech Connect

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.

Anthony Leonard; Phillippe Chatelain; Michael Rebel

2004-09-30

260

Permian fossils from the Greenhills group, Bluff, Southland, New Zealand  

Microsoft Academic Search

Rare fossils including the gastropod Peruvispira aff. imbricata Waterhouse and the bivalve Atomodesma aff. marwicki Waterhouse indicate a late Lower Permian age for the middle part of the Greenhills Group. Plerophyllum aff. timorense Gerth occurs in a lower horizon of the Greenhills Group. Bands of marble containing shell prisms, rare radiolarians, and other microfossils occur in the upper part of

David J. Mossman; Lucy M. Force

1969-01-01

261

Preliminary Investigation of Integrated Bluff Protective Systems for Lake Erie.  

National Technical Information Service (NTIS)

The Lake Erie shoreline in Lake County is receding from one to five feet per year. There are no organized efforts to halt the recession and individual protection efforts have been mostly ineffective. The purpose of this thesis is to determine the physical...

W. D. Reynolds

1979-01-01

262

CONTROL OF FLOW PAST BLUFF BODIES USING ROTATING CONTROL CYLINDERS  

Microsoft Academic Search

Computational results for control of flow past a circular cylinder using small rotating cylinders are presented. A well-proven stabilized finite-element method, that has been applied to various flow problems earlier, is utilized to solve the incompressible Navier–Stokes equations in the primitive variables formulation. The formulation is first applied to study flow past an isolated rotating cylinder. Excellent match with experimental

S. Mittal

2001-01-01

263

Mansion on the Bluff Catches Lives on the Edge.  

ERIC Educational Resources Information Center

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…

Priem, Shannon

1998-01-01

264

White Bluffs Pickling Acid Cribs expedited response action proposal.  

National Technical Information Service (NTIS)

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 Bl...

1993-01-01

265

Turbulence Models and Boundary Conditions for Bluff Body Flow  

Microsoft Academic Search

Two aspects of turbulence modelling were addressed with re- spect to a single cylinder in crossflow. Firstly, the effect of vary- ing the turbulent length scale at the inlet was investigated at a high subcritical Reynolds number of 1.4 × 105. Variations of up to 14% were noted in the flow properties such as mean drag and Strouhal number, but

M. E. Young; A. Ooi

266

Mansion on the Bluff Catches Lives on the Edge.  

ERIC Educational Resources Information Center

|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…

Priem, Shannon

1998-01-01

267

Cave Formation: Kane Cave  

NSDL National Science Digital Library

This video documents an experiment conducted in Kane Cave, Wyoming, to see if microbes that inhabit the cave could actually be contributing to the cave-formation process. Adapted from a NOVA broadcast, the segment is four minutes and twelve seconds in length.

2010-11-25

268

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...

269

Formation of Giant Planets.  

National Technical Information Service (NTIS)

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 5...

D. Lin

1999-01-01

270

Pattern formation during electropolishing  

Microsoft Academic Search

Using atomic force microscopy, we find that the surface morphology of a dissolving aluminum anode in a commercial electropolishing electrolyte can exhibit both highly regular and randomly packed stripe and hexagonal patterns with amplitudes of about 5 nm and wavelengths of 100 nm. The driving instability of this pattern formation phenomenon is proposed to be the preferential adsorption of polar

Vadim V. Yuzhakov; Hsueh-Chia Chang; Albert E. Miller

1997-01-01

271

Ultrarelativistic black hole formation  

NASA Astrophysics Data System (ADS)

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.

East, William; Pretorius, Frans

2013-04-01

272

Formation of neutrino halos.  

NASA Astrophysics Data System (ADS)

A fully general relativistic non-linear model of the formation of massive neutrino halos in an Einstein-Straus universe was given by Fabbri, Jantzen and Ruffini. Here the author considers the role which a non-vanishing, repulsive cosmological constant ? > 0, admissible by observational limits, can have in the FJR model.

Stuchlík, Z.

273

Bargaining and Coalition Formation  

Microsoft Academic Search

This paper provides a su¢ cient condition for the non-emptiness of the core in coalition for- mation such as the formation of clubs, partnerships, …rms, business alliances, and jurisdictions voting on public goods. The condition is formulated for settings in which agents …rst form coalitions and then each coalition realizes a payopro…le from the set of available alternatives via mechanisms

Marek Pycia; Penn State

274

Formation of Language  

Microsoft Academic Search

PERMIT me to reply to your correspondent Mr. W. J. Stillman, on the ``Formation of Language'' (NATURE, March 26, p. 491). The interesting fact he records of the spontaneous invention and use of child-names for objects is not unknown to philologists. The phenomenon has been previously noticed, among others, by Miss Watson, of Boston, and Dr. E. R. Hun, of

Agnes Crane

1891-01-01

275

Frazil Ice Formation.  

National Technical Information Service (NTIS)

Frazil ice forms in flowing or turbulent water that has become supercooled by heat transfer to overlying air. This report investigates the influences of turbulence and water temperature on frazil ice formation. The rate and the quantity of frazil ice form...

R. Ettema M. F. Karim J. F. Kennedy

1984-01-01

276

Formation in the Classroom  

ERIC Educational Resources Information Center

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…

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

2011-01-01

277

The Formation of Trihalomethanes.  

ERIC Educational Resources Information Center

|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)|

Trussell, R. Rhodes; Umphres, Mark D.

1978-01-01

278

Formation in the Classroom  

ERIC Educational Resources Information Center

|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…

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

2011-01-01

279

Technobabble: File Formats.  

ERIC Educational Resources Information Center

|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)|

Wilson, Bradley

1999-01-01

280

Computational Star Formation (IAU S270)  

NASA Astrophysics Data System (ADS)

1. Historical introduction; 2. Individual star formation: observations; 3. Low-mass star formation: observations; 4. Individual star formation: theory; 5. Formation of clusters: observations; 6. Formation of clusters: theory; 7. Numerical methods: MHD; 8. Numerical methods: radiative dynamics; 9. Local star formation processes; 10. Star formation feedback; 11. Star formation on galactic scales; 12. Special purpose hardware; 13. Computational methods; 14. Radiation diagnostics of star formation; 15. Large scale star formation; 16. Cosmological star formation; 17. Computational star formation: Summary; Index.

Alves, João.; Elmegreen, Bruce G.; Girart, Josep M.; Trimble, Virginia

2011-05-01

281

Pattern formation today  

PubMed Central

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.

Chuong, Cheng-Ming; Richardson, Michael K.

2010-01-01

282

Global Star-Formation Rates  

Microsoft Academic Search

I review the basic modes of quiescent star formation and starbursts. Star-formation efficiency is the key to reconciling hierarchical\\u000a galaxy formation with observed galaxy colours and counts. A unified viewpoint is that all star formation is, at some level,\\u000a bursty. This is motivated both by local observations and by theory. I describe how self-regulation of star formation provides\\u000a prescriptions for

Joseph Silk

2005-01-01

283

External triggers of star formation  

Microsoft Academic Search

The local processes leading to star-formation are not well known; gravitational instabilities can be triggered by shocks and stellar winds, and it is believed that star-formation can thus propagate. Cloud-cloud collisions have been assumed to trigger star-formation or at least giant molecular clouds formation. On the kpc scale, the star-formation rate seems to be proportional to some power of the

F. Combes

1993-01-01

284

Pattern formation during vasculogenesis  

PubMed Central

Vasculogenesis, the assembly of the first vascular network, is an intriguing developmental process that yields the first functional organ system of the embryo. In addition to being a fundamental part of embryonic development, vasculogenic processes also have medical importance. To explain the organizational principles behind vascular patterning, we must understand how morphogenesis of tissue level structures can be controlled through cell behavior patterns that, in turn, are determined by biochemical signal transduction processes. Mathematical analyses and computer simulations can help conceptualize how to bridge organizational levels and thus help in evaluating hypotheses regarding the formation of vascular networks. Here we discuss the ideas that have been proposed to explain the formation of the first vascular pattern: cell motility guided by extracellular matrix alignment (contact guidance), chemotaxis guided by paracrine and autocrine morphogens, and sprouting guided by cell-cell contacts.

Czirok, Andras; Little, Charles D.

2012-01-01

285

Mechanisms of Stone Formation  

Microsoft Academic Search

We have reviewed the general mechanisms involved in kidney stone formation, with reference to those composed of calcium oxalate\\u000a or phosphate, uric acid, and cystine. These processes include nucleation of individual crystals, aggregation or secondary\\u000a nucleation to produce small intrarenal multicrystalline aggregates, fixation within the kidney, and further aggregation and\\u000a secondary nucleation to produce the clinical stone. The factors regulating

Vishal N. Ratkalkar; Jack G. Kleinman

286

Drumlin Formation Library Work  

NSDL National Science Digital Library

Students will individually produce a written introduction for a paper about the presence of drumlins on Mars - this introduction describes different models for drumlin formation on earth. To prepare for this assignment, students work in groups to do library research to find and read articles. The groups summarize their findings for each other. Each student then writes an introduction incorporating material from all the groups. Designed for a geomorphology course Uses geomorphology to solve problems in other fields

Anders, Alison M.

287

GALEX and star formation  

Microsoft Academic Search

Wide-field far-UV (FUV, 1344–1786 Å) and near-UV (NUV, 1771–2831 Å) imaging from GALEX provides a deep, comprehensive view of the young stellar populations in hundreds of nearby galaxies, shedding new light on\\u000a the process of star formation (SF) in different environments, and on the interplay between dust and SF. GALEX’s FUV-NUV color is extremely sensitive to stellar populations of ages up to

Luciana Bianchi

2011-01-01

288

Cave Formation: Biogeochemical Cycles  

NSDL National Science Digital Library

This video explores the role of biogeochemical cycles in the formation of caves. It discusses a radical new theory that identifies sulfuric acid as a cave-forming agent. The video, adapted from a NOVA broadcast, identifies the source of the sulfuric acid, which, unlike carbonic acid, the typical cave-forming agent, does not readily form in nature. The segment is 5 minutes and forty seconds in length.

289

Chemistry of planet formation  

NASA Astrophysics Data System (ADS)

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 .

Robinson, Sarah Elaine

2008-02-01

290

Terrestrial planet formation  

PubMed Central

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.

Righter, K.; O'Brien, D. P.

2011-01-01

291

Flocks and Formations  

NASA Astrophysics Data System (ADS)

Given a large number (the "flock") of moving physical objects, we investigate physically reasonable mechanisms of influencing their orbits in such a way that they move along a prescribed course and in a prescribed and fixed configuration (or "in formation"). Each agent is programmed to see the position and velocity of a certain number of others. This flow of information from one agent to another defines a fixed directed (loopless) graph in which the agents are represented by the vertices. This graph is called the communication graph. To be able to fly in formation, an agent tries to match the mean position and velocity of his neighbors (his direct antecedents on the communication graph) to his own. This operation defines a (directed) Laplacian on the communication graph. A linear feedback is used to ensure stability of the coherent flight patterns. We analyze in detail how the connectedness of the communication graph affects the coherence of the stable flight patterns and give a characterization of these stable flight patterns. We do the same if in addition the flight of the flock is guided by one or more leaders. Finally we use this theory to develop some applications. Examples of these are: flight guided by external controls, flocks of flocks, and some results about flocks whose formation is always oriented along the line of flight (such as geese).

Veerman, J. J. P.; Lafferriere, G.; Caughman, J. S.; Williams, A.

2005-12-01

292

Simulation of galaxy formation  

NASA Astrophysics Data System (ADS)

This thesis presents a detailed study of the simulation of galaxy formation in the cold dark matter (CDM) cosmology. Smoothed Particle Hydrodynamics (SPH) is used to follow the hydrodynamics within the simulations and an analysis of the performance of twelve different implementations of SPH is presented. Seven tests are used which are designed to isolate key hydrodynamic elements of cosmological simulations. It is shown that the artificial viscosity is the single most important factor in determining results. The way in which force symmetry is achieved in the equation of motion has a secondary effect. Most results favour a kernel symmetrization approach. A detailed description of a method for simulating the formation of individual galaxies is given. Gas regions which fall within temperature, density, self- gravity and convergent-flow criteria are assumed to form stars. A Lagrangian Schmidt Law is used to calculate the star formation rate. Feedback from supernovae is incorporated by returning thermal energy to the inter- stellar medium. Radiative losses are prevented from heated particles by adjusting the radiative cooling mechanism. The model is tested on isolated disc galaxies as well as galaxies formed from cosmological initial conditions. A discussion is presented on the implementation of `HYDRA', a combined hydrodynamic and gravity N-body particle integrator, on shared-memory architectures with a symmetric multi- processor configuration (SMP). Parallelization is achieved using the directives in the OpenMP application program interface. The performance of the code is examined for up to 128 processors and excellent scaling is found, provided a large enough problem is studied. A high resolution simulation is presented which satisfies a number of criteria for accuracy defined in the SPH tests. Due to limitations of the parallel code it was not possible to integrate the simulation to the desired final epoch. At high resolution gas in-fall is seen to be highly unsmooth, and the gas appears to lose angular momentum more rapidly. Although higher resolution prevents the formation of very dense gas cores it does not entirely prevent the condensation of cold gas. Prospects for the future of the simulation field, and the CDM model of structure formation are given.

Thacker, Robert John

1999-10-01

293

Formation Flying In Highly Elliptical Orbits Initializing the Formation.  

National Technical Information Service (NTIS)

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 Multi...

L. Mailhe C. Schiff S. Hughes

2000-01-01

294

Formation of neutrino halos  

NASA Astrophysics Data System (ADS)

A fully general relativistic nonlinear model of the formation of massive neutrino halos in an Einstein-Straus universe was given by Fabbri, Jantzen and Ruffini (1982). The paper considers the role which a nonvanishing, repulsive cosmological constant Lambda greater than 0, admissible by observational limits, can have in the FJR model. The main conclusion is that the influence of Lambda is negligible in the FJR model for massive neutrinos with mass of about 10 eV, indicated by recent observations of SN 1987a. On the other hand, the cosmological constant is relevant in the model, if neutrinos have low mass, less than 0.2 eV.

Stuchlik, Zdenek

295

Adiabatic Halo Formation  

SciTech Connect

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.

Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G. [Physics Department University of Bologna, INFN Bologna, via Irnerio 46 40126 Bologna Italy (Italy)

2005-06-08

296

Ultrarelativistic black hole formation.  

PubMed

We study the head-on collision of fluid particles well within the kinetic energy dominated regime (? = 8 to 12) by numerically solving the Einstein-hydrodynamic equations. We find that the threshold for black hole formation is lower (by a factor of a few) than simple hoop conjecture estimates, and, moreover, near this threshold two distinct apparent horizons first form postcollision and then merge. We argue that this can be understood in terms of a gravitational focusing effect. The gravitational radiation reaches luminosities of 0.014 c(5)/G, carrying 16 ± 2% of the total energy. PMID:23521246

East, William E; Pretorius, Frans

2013-03-07

297

Kepler Data Formats  

NASA Astrophysics Data System (ADS)

The Kepler data archive will endeavor to provide access to mission data in convenient formats for astronomical researchers. The Kepler photometer will accumulate single-bandpass counts on 170,000 targets at a cadence of 30 min. Since archive users are expected to typically access data by astronomical source, pixels from each cadence will be sorted into files by target star. Files that contain the raw pixel values, calibrated pixel values, and calibrated flux for each target will be available from the Kepler archive. Ancillary engineering, collateral, and background data will also be available. All Kepler data will be subject to proprietary rights restrictions based on time and target.

Swade, D. A.

2007-10-01

298

Modeling river delta formation  

PubMed Central

A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River.

Seybold, Hansjorg; Andrade, Jose S.; Herrmann, Hans J.

2007-01-01

299

Formation of the Solar System  

NSDL National Science Digital Library

This animation depicts the formation of the solar system from a solar nebula, a great swirling cloud of gas and dust. It is accompanied by a link to a written description explaining the solar system's formation in greater detail.

300

Star Formation in Irregular Galaxies.  

ERIC Educational Resources Information Center

|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)|

Hunter, Deidre; Wolff, Sidney

1985-01-01

301

Star Formation a Literature Survey.  

National Technical Information Service (NTIS)

The formation of stars from galactic clouds is considered. Dynamic collapse, fragmentation, and the Helmholtz-Kelvin contraction are discussed. Galactic cloud rotation and the influence of a magnetic field on stellar evolution are reviewed. The formation ...

P. Ingvarson

1970-01-01

302

Star formation and the Galaxy  

Microsoft Academic Search

This review discusses the extent of star formation in the Milky Way with emphasis on the role of large-scale phenomena. Consideration is given to the problems of star formation in the disk in the particular context of density-wave shock theory. Some tests of the relationships between the density-wave shock and star formation, the rate of star formation, the role of

F. J. Kerr

1977-01-01

303

Identity Formation During Early Adolescence  

Microsoft Academic Search

A special issue of the Journal of Early Adolescence has been prepared to address theoretical and research issues concerning identity formation during early adolescence. The issue has been designed to help direct and stimulate interest in research on identity formation during early adolescence. In these introductory comments the major tenets of Erikson's psychosocial theory of identity formation are outlined, the

Gerald R. Adams; Raymond Montemayor

1983-01-01

304

Initial Conditions for Star Formation  

Microsoft Academic Search

Recent studies have provided important information on the initial conditions for the formation of low mass stars. These studies, using submillimeter continuum and line observations, have identified objects in the earliest stages of star formation as cold, dense cores in which most molecules are frozen onto dust grains. We are placing constraints on different theories of star formation with these

N. J. Evans

2002-01-01

305

Star Formation in Spiral Arms  

Microsoft Academic Search

The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the

B. G. Elmegreen

2011-01-01

306

Format Integration and Serials Cataloging  

Microsoft Academic Search

Format integration has achieved some goals: Seriality of nonprint materials can be expressed. Materials in several physical formats can be described. Archival control of non-print materials can be designated. Content designation has been standardized. Validation routines have been simplified or eliminated. Documentation has been much reduced. Format integration also brings new problems and issues. Bibliographic records are more complex, partly

Judith Johnston Recorder

1997-01-01

307

Bone formation by cancer metastases  

Microsoft Academic Search

The formation of heterotopic bone tissue in malignant tumors or in their metastases is extremely rare. In a 60 years old male patient with bronchogenic carcinoma (adenocarcinoma) extensive bone formation was observed within multiple metastases in the skeletal muscles. On the basis of the microscopic findings, the mechanism of bone formation by malignant tumors is discussed. Obviously, proliferation of local

U. Bettendorf; W. Remmele; H. Laaff

1976-01-01

308

Multiple fracturing of subterranean formations  

Microsoft Academic Search

A method of fracturing subterranean formations is described wherein a formation is fractured and propped 2 or more times to increase the width of the propped fracture. The method involves the steps of propping the fracture with particulate material, consolidating the particulate material into a permeable mass, and thereafter refracturing the formation and then propping the fracture produced by the

C. E. Jr. Cooke; J. W. Graham; T. W. Muecke

1976-01-01

309

Method for treating subterranean formations  

SciTech Connect

A method for treating a subterranean formation comprised of placing in or adjacent the formation a quantity of free-flowing, heat curable particles comprised of a high strength center, a coupling agent chemically bound to the center, a heat curable resin coated over the center; and causing said free flowing particles in or adjacent the formation to form a cohesive mass.

Graham, J. W.; Sinclair, A. R.

1985-05-21

310

Explosions During Galaxy Formation  

NASA Astrophysics Data System (ADS)

As an idealized model of the effects of energy release by supernovae during galaxy formation, we consider an explosion at the center of a halo which forms at the intersection of filaments in the plane of a cosmological pancake by gravitational instability during pancake collapse. Such halos resemble the virialized objects found in N-body simulations in a CDM universe and, therefore, serve as a convenient, scale-free test-bed model for galaxy formation. ASPH/P3M simulations reveal that such explosions are anisotropic. The energy and metals are channeled into the low density regions, away from the pancake plane. The pancake remains essentially undisturbed, even if the explosion is strong enough to blow away all the gas located inside the halo at the onset of the explosion and reheat the IGM surrounding the pancake. Infall quickly replenishes this ejected gas and gradually restores the gas fraction as the halo mass continues to grow. Estimates of the collapse epoch and SN energy-release for galaxies of different mass in the CDM model can relate these results to scale-dependent questions of blow-out and blow-away and their implication for early IGM heating and metal enrichment and the creation of dark-matter-dominated dwarf galaxies.

Martel, H.; Shapiro, P. R.

2001-03-01

311

Planet Formation and Migration  

NASA Astrophysics Data System (ADS)

The discovery of over 160 extrasolar planets, many with very unusual properties, has driven a renaissance in the study of planet formation. It is likely that Jovian and supra-Jovian planets formed at large distances, migrated towards their central stars, and yet somehow managed to stop short of plunging in. The growing theoretical and observational study of protostellar disks is allowing us to better probe the mechanism(s) of planet formation and migration through disk-gas interactions. In this talk, we explore new insights in mechanisms for determing planetary masses that arise from the presence of turbulence-free, so called dead-zones in protostellar disks. Such regions should be present on scales of up to 15 AU in most disks and should have profound effects on the migration of both terrestrial and Jovian planets - in effect - saving planetary systems. We also explore some obervational consequences of such ideas for observing programmes that can be implemented at the planned new large-scale ground-based facilities; TMT and SKA.

Pudritz, Ralph E.; Matsumura, S.

2006-06-01

312

Egg Formation in Lepidoptera  

PubMed Central

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.

Telfer, William H.

2009-01-01

313

Biofilm formation by haloarchaea.  

PubMed

A fluorescence-based live-cell adhesion assay was used to examine biofilm formation by 20 different haloarchaea, including species of Halobacterium, Haloferax and Halorubrum, as well as novel natural isolates from an Antarctic salt lake. Thirteen of the 20 tested strains significantly adhered (P-value ?< 0.05) to a plastic surface. Examination of adherent cell layers on glass surfaces by differential interference contrast, fluorescence and confocal microscopy showed two types of biofilm structures. Carpet-like, multi-layered biofilms containing micro- and macrocolonies (up to 50 ?m in height) were formed by strains of Halobacterium salinarum and the Antarctic isolate t-ADL strain DL24. The second type of biofilm, characterized by large aggregates of cells adhering to surfaces, was formed by Haloferax volcanii DSM 3757T and Halorubrum lacusprofundi DL28. Staining of the biofilms formed by the strongly adhesive haloarchaeal strains revealed the presence of extracellular polymers, such as eDNA and glycoconjugates, substances previously shown to stabilize bacterial biofilms. For Hbt. salinarum DSM 3754T and Hfx. volcanii DSM 3757T , cells adhered within 1 day of culture and remained viable for at least 2 months in mature biofilms. Adherent cells of Hbt. salinarum DSM 3754T showed several types of cellular appendages that could be involved in the initial attachment. Our results show that biofilm formation occurs in a surprisingly wide variety of haloarchaeal species. PMID:23057712

Fröls, Sabrina; Dyall-Smith, Mike; Pfeifer, Felicitas

2012-10-12

314

Pine Island Iceberg Formation  

NSDL National Science Digital Library

This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continents fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event.

Perkins, Lori; Bindschadler, Bob; Diner, Dave

2002-01-10

315

Transitions in biofilm formation  

NASA Astrophysics Data System (ADS)

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.

Gordon, Vernita; Thatcher, Travis; Cooley, Benjamin

2011-03-01

316

The Argument Interchange Format  

NASA Astrophysics Data System (ADS)

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.

Rahwan, Iyad; Reed, Chris

317

Mechanism of GEMS formation  

SciTech Connect

GEMS (glass with embedded metal and sulfides) in interplanetary dust particles (IDPs) were examined using 200 keV analytical transmission electron microscopy. The morphologies and crystallography of embedded relict grains reveal that GEMS are pseudomorphs formed by irradiation processing of crystals free-floating in space. Some GEMS retain a compositional and morphological ''memory'' of the crystal from which they formed. Pseudomorphism rules out condensation, annealing, flash heating, or shock melting as alternative mechanisms of GEMS formation. A significant and often dominant fraction of the atoms in GEMS were sputtered deposited from other grains. Therefore, a normal (solar) isotopic composition is not a reliable indicator of whether GEMS formed in the solar system or in presolar interstellar or circumstellar environments.

Bradley, J P; Dai, Z R

2004-03-10

318

Cellular pattern formation  

NASA Astrophysics Data System (ADS)

This thesis studies the formation and evolution of cellular patterns in foams and living organisms using the extended large-Q Potts model. Specific problems include grain growth, foam drainage, foam rheology, and patterning and cell sorting in the mound phase of the slime mode Dictyostelium discoideum. In a wide range of cellular materials, surface-energy-driven diffusion leads to boundary motion which causes some grains to expend and others to shrink. Two-dimensional large-Q Potts model simulation of the evolution of a disordered cluster developed from a hexagonal grain array with a defect shows that abnormal grain growth can occur without strong anisotropy of surface energy. The grains at the boundary of the disordered cluster reach a special scaling state with no scale change. In three-dimensional liquid foams, drainage occurs due to gravity. Large-Q Potts model simulations, extended to include gravity in three dimensions, agree with both experimental and analytical results for various kinds of foam drainage, and also predict new phenomena. Foams exhibit a unique rheological transition from solid-like to fluid-like. Simulations using the large-Q Potts model, extended to apply shear to a two-dimensional foam, show three different types of hysteresis in foam's stress-strain relationship, which correspond to the elastic, viscoelastic and viscous fluid properties. This wide-ranging mechanical response depends on the structure and dynamics of local topological rearrangement of foam cells. Biological tissues resemble foams and the large-Q Potts model can also simulate sorting in biological cell aggregates. In Dictyostelium mound, two types of cells are initially randomly distributed. In time, one cell type sorts to form a tip. Simulations show that both differential adhesion and chemotaxis are required for sorted tip formation. With only differential adhesion, no tip forms. With only chemotaxis, a tip forms containing both cell types. Thus simulations can provide a method to determine the processes necessary for biological patterning.

Jiang, Yi

319

Updated diatom biostratigraphy for Monterey Formation  

SciTech Connect

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.

Barron, J.A.

1986-04-01

320

Large Format Radiographic Imaging  

SciTech Connect

Radiographic imaging continues to be a key diagnostic in many areas at Los Alamos National Laboratory (LANL). Radiographic recording systems have taken on many form, from high repetition-rate, gated systems to film recording and storage phosphors. Some systems are designed for synchronization to an accelerator while others may be single shot or may record a frame sequence in a dynamic radiography experiment. While film recording remains a reliable standby in the radiographic community, there is growing interest in investigating electronic recording for many applications. The advantages of real time access to remote data acquisition are highly attractive. Cooled CCD camera systems are capable of providing greater sensitivity with improved signal-to-noise ratio. This paper begins with a review of performance characteristics of the Bechtel Nevada large format imaging system, a gated system capable of viewing scintillators up to 300 mm in diameter. We then examine configuration alternatives in lens coupled and fiber optically coupled electro-optical recording systems. Areas of investigation include tradeoffs between fiber optic and lens coupling, methods of image magnification, and spectral matching from scintillator to CCD camera. Key performance features discussed include field of view, resolution, sensitivity, dynamic range, and system noise characteristics.

J. S. Rohrer; Lacey Stewart; M. D. Wilke; N. S. King; S. A Baker; Wilfred Lewis

1999-08-01

321

Pattern formation during electropolishing  

NASA Astrophysics Data System (ADS)

Using atomic force microscopy, we find that the surface morphology of a dissolving aluminum anode in a commercial electropolishing electrolyte can exhibit both highly regular and randomly packed stripe and hexagonal patterns with amplitudes of about 5 nm and wavelengths of 100 nm. The driving instability of this pattern formation phenomenon is proposed to be the preferential adsorption of polar or polarizable organic molecules on surface ridges where the contorted double layer produces a higher electric potential gradient. The enhanced relative coverage shields the anode and induces a smaller dissolution rate at the ridges. The instability is balanced by surface diffusion of the adsorbate to yield a length scale of 4?(Ds/kd)1/2, where Ds is the surface diffusivity and kd is the desorption coefficient of the adsorbate, which correlates well with the measured wavelength. A long-wavelength expansion of the double-layer field yields an interface evolution equation that reproduces all of the observed patterns. In particular, bifurcation analysis and numerical simulation yield a single voltage-dependent dimensionless parameter ? that measures a balance between smoothing of adsorbate concentration by electric-field-dependent surface diffusion and fluctuation due to interfacial curvature and stretching. Randomly oriented stripes are favored at large ? (low voltage), while random hills dominate at small ? (high voltage) with perfectly periodic stripes and hexagonal hill patterns within a small window near ?=1. These predictions are in qualitative and quantitative agreement with our measurements.

Yuzhakov, Vadim V.; Chang, Hsueh-Chia; Miller, Albert E.

1997-11-01

322

Microbial formation of esters.  

PubMed

Small aliphatic esters are important natural flavor and fragrance compounds and have numerous uses as solvents and as chemical intermediates. Besides the chemical or lipase-catalyzed formation of esters from alcohols and organic acids, small volatile esters are made by several biochemical routes in microbes. This short review will cover the biosynthesis of esters from acyl-CoA and alcohol condensation, from oxidation of hemiacetals formed from aldehydes and alcohols, and from the insertion of oxygen adjacent to the carbonyl group in a straight chain or cyclic ketone by Baeyer-Villiger monooxygenases. The physiological role of the ester-forming reactions can allow degradation of ketones for use as a carbon source and may play a role in detoxification of aldehydes or recycling cofactors. The enzymes catalyzing each of these processes have been isolated and characterized, and a number of genes encoding the proteins from various microbes have been cloned and functionally expressed. The use of these ester-forming organisms or recombinant organisms expressing the appropriate genes as biocatalysts in biotechnology to make specific esters and chiral lactones has been studied in recent years. PMID:19714327

Park, Yong Cheol; Shaffer, Catherine Emily Horton; Bennett, George N

2009-11-01

323

Colloid formation in implanted glasses  

Microsoft Academic Search

Metal colloids in glasses can yield an enhanced ([chi]([sup 3])) susceptibility which leads to an intensity dependent refractive index. Ion implantation is a convenient means of introducing the metal species. The host glass plays an important role in colloid formation. We have characterized Ag-colloid formation in various silicate glasses and, in addition, have studied the formation of colloids in Ag-doped

G. W. Arnold; P. Mazzoldi; L. Tramontin; A. Boscolo-Boscoletto; G. Battaglin

1992-01-01

324

Colloid formation in implanted glasses  

Microsoft Academic Search

Metal colloids in glasses can yield an enhanced (Ï(³)) susceptibility which leads to an intensity dependent refractive index. Ion implantation is a convenient means of introducing the metal species. The host glass plays an important role in colloid formation. We have characterized Ag-colloid formation in various silicate glasses and, in addition, have studied the formation of colloids in Ag-doped phosphate

G. W. Arnold; P. Mazzoldi; L. Tramontin; A. Boscolo-Boscoletto; G. Battaglin

1992-01-01

325

Struvite scale formation and control.  

PubMed

Struvite scale formation is a major operational issue at both conventional and biological nutrient removal wastewater treatment plants. Factors affecting the formation of struvite scales were investigated including supersaturation, pH and pipe material and roughness. A range of control methods have been investigated including low fouling materials, pH control, inhibitor and chemical dosing. Control methods exist to reduce scale formation although each has its advantages and disadvantages. PMID:14982179

Parsons, S A; Doyle, J D

2004-01-01

326

Star Formation in Spiral Arms  

Microsoft Academic Search

The origin and types of spiral arms are reviewed with an emphasis on the\\u000aconnections between these arms and star formation. Flocculent spiral arms are\\u000amost likely the result of transient instabilities in the gas that promote dense\\u000acloud formation, star formation, and generate turbulence. Long irregular spiral\\u000aarms are usually initiated by gravitational instabilities in the stars, with\\u000athe

Bruce G. Elmegreen

2011-01-01

327

Formation flying in elliptical orbits  

Microsoft Academic Search

We present a general approach to the analysis of the formation flying problem, based on FreeFlyer(R) and MATLAB(R), that is designed with spacecraft formations in mind. With this approach, we are able to quickly combine new algorithms for the initialization and control of a formation within the context of a high-fidelity operational tool. As an example, we can use a

Conrad Schiff; D. Rohrbaugh; J. Bristow

2000-01-01

328

Modelling the ISM and Star Formation in Galaxy Formation Simulations  

NASA Astrophysics Data System (ADS)

Using a set of 60 Tree-SPH simulations of the formation of an individual galaxy, including star formation physics, we quantitatively assess the numerical accuracy and convergence of these methods. For simulations using 24000 particles in total, the gross structures of the resultant galaxies are reliably resolved.

Williams, P. R.; Nelson, A. H.

2004-06-01

329

Dwarf Galaxy Formation with H2-regulated Star Formation  

NASA Astrophysics Data System (ADS)

We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star formation prescription regulated by the local abundance of molecular hydrogen. We show that this H2-regulated prescription leads to a suppression of star formation in low-mass halos (Mh <~ 1010 M ?) at z > 4, alleviating some of the dwarf galaxy problems faced by theoretical galaxy formation models. H2 regulation modifies the efficiency of star formation of cold gas directly, rather than indirectly reducing the cold gas content with "supernova feedback." We determine the local H2 abundance in our most refined grid cells (76 proper parsec in size at z = 4) by applying the model of Krumholz, McKee, & Tumlinson, which is based on idealized one-dimensional radiative transfer calculations of H2 formation-dissociation balance in ~100 pc atomic-molecular complexes. Our H2-regulated simulations are able to reproduce the empirical (albeit lower z) Kennicutt-Schmidt relation, including the low ?gas cutoff due to the transition from atomic to molecular phase and the metallicity dependence thereof, without the use of an explicit density threshold in our star formation prescription. We compare the evolution of the luminosity function, stellar mass density, and star formation rate density from our simulations to recent observational determinations of the same at z = 4-8 and find reasonable agreement between the two.

Kuhlen, Michael; Krumholz, Mark R.; Madau, Piero; Smith, Britton D.; Wise, John

2012-04-01

330

Microdiamonds Formation During  

NASA Astrophysics Data System (ADS)

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.

Ogasawara, Y.

2005-12-01

331

Pattern formation during electropolishing  

SciTech Connect

Using atomic force microscopy, we find that the surface morphology of a dissolving aluminum anode in a commercial electropolishing electrolyte can exhibit both highly regular and randomly packed stripe and hexagonal patterns with amplitudes of about 5 nm and wavelengths of 100 nm. The driving instability of this pattern formation phenomenon is proposed to be the preferential adsorption of polar or polarizable organic molecules on surface ridges where the contorted double layer produces a higher electric potential gradient. The enhanced relative coverage shields the anode and induces a smaller dissolution rate at the ridges. The instability is balanced by surface diffusion of the adsorbate to yield a length scale of 4{pi}(D{sub s}/k{sub d}){sup 1/2}, where D{sub s} is the surface diffusivity and k{sub d} is the desorption coefficient of the adsorbate, which correlates well with the measured wavelength. A long-wavelength expansion of the double-layer field yields an interface evolution equation that reproduces all of the observed patterns. In particular, bifurcation analysis and numerical simulation yield a single voltage-dependent dimensionless parameter {xi} that measures a balance between smoothing of adsorbate concentration by electric-field-dependent surface diffusion and fluctuation due to interfacial curvature and stretching. Randomly oriented stripes are favored at large {xi} (low voltage), while random hills dominate at small {xi} (high voltage) with perfectly periodic stripes and hexagonal hill patterns within a small window near {xi}=1. These predictions are in qualitative and quantitative agreement with our measurements. {copyright} {ital 1997} {ital The American Physical Society}

Yuzhakov, V.V.; Chang, H.; Miller, A.E. [Department of Chemical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

1997-11-01

332

Formation of Giant Planets  

NASA Astrophysics Data System (ADS)

The observed properties of giant planets, models of their evolution, and observations of protoplanetary disks provide constraints on the formation of gas giant planets. The four largest planets in our solar system contain considerable quantities of hydrogen and helium; these gases could not have condensed into solid planetesimals within the protoplanetary disk. Jupiter and Saturn are mostly hydrogen and helium, but have larger abundances of heavier elements than does the Sun. Neptune and Uranus are primarily composed of heavier elements. The transiting extrasolar planet HD149026b, which is slightly more massive than Saturn, appears to have comparable amounts of light gases and heavy elements. The other observed transiting exoplanets are primarily hydrogen and helium, but may contain supersolar abundances of heavy elements. Spacecraft flybys and observations of satellite orbits provide estimates of the gravitational moments of the giant planets in our solar system, which in turn provide information on the internal distribution of matter within Jupiter, Saturn, Uranus, and Neptune. Atmospheric thermal structure and heat flow measurements constrain the interior temperatures of these planets. Internal processes may cause giant planets to become more compositionally differentiated or alternatively more homogeneous; high-pressure laboratory experiments provide data useful for modeling these processes. The preponderance of evidence supports the core nucleated gas accretion model. According to this model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the giant planet cores grow massive enough to accumulate substantial amounts of gas before the protoplanetary disk dissipates. The primary question regarding the core nucleated growth model is under what conditions can planets develop cores sufficiently massive to accrete gas envelopes within the lifetimes of gaseous protoplanetary disks.

Lissauer, J. J.; Stevenson, D. J.

333

ANTIBODY FORMATION IN VITRO  

PubMed Central

Neutralizing activity against T2 bacteriophage appeared in cultures of lymph node cells from normal rats in response to their in vitro stimulation with a cell-free filtrate derived from homogenized rat macrophages which had been incubated with T2 bacteriophage. This activity was specifically directed against T2 bacteriophage. It resided in a fraction of the culture fluid which had the salting-out properties of serum globulin. Phage neutralization was inhibited by antibody specific for rat serum gamma globulin. Antibody production against T2 bacteriophage in cultures of lymph node cells from normal animals failed to occur if (a) T2 bacteriophage alone was added, (b) if the incubation period of macrophages and T2 phage was unduly shortened, (c) if the cell-free filtrate was heated at 80–100°C for 15 minutes, (d) if more than an optimal amount of T2 bacteriophage was added to the macrophages. Additional factors which prevented the formation of antibody were the heat inactivation of the lymph node cells or the addition to the culture medium of either streptomycin or ribonuclease. Finally, it was found that macrophages and lymph node cells had to be obtained from animals of one and the same species. All essential findings on the production of antibody to T2 bacteriophage in vitro could be confirmed by substitution of the chick embryo for the tissue culture medium. The results are discussed in terms of a possible mechanism of antibody production in which an RNAse-sensitive substance resulting from the interaction of macrophages and antigen is capable of stimulating antibody synthesis in lymphocytic cells.

Fishman, M.

1961-01-01

334

The Principal as Formative Coach  

ERIC Educational Resources Information Center

|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…

Nidus, Gabrielle; Sadder, Maya

2011-01-01

335

The formation of tropical cyclones  

Microsoft Academic Search

Summary This paper attempts a synthesis of new observations and new concepts on how tropical cyclone formation occurs. Despite many worthy observational and numerical modeling studies in recent decades, our understanding of the detailed physical processes associated with the early stages of tropical cyclone formation is still inadequate; operational forecast skill is not very high. Although theoretical ideas cover a

W. M. Gray

1998-01-01

336

Formation control using generalized coordinates  

Microsoft Academic Search

This paper develops a control methodology which allows a number of vehicles to move as a group while maintaining a desired formation pattern. The control is based on the use of generalized coordinates. These coordinates characterize the location (L), orientation (O), and shape (S) of the formation. This provides a natural and convenient way of specifying configuration and allows the

Stephen Spry; J. Karl Hedrick

2004-01-01

337

New Frontiers in Formative Assessment  

ERIC Educational Resources Information Center

|"Formative assessment is a powerful learning tool that is too seldom, too haphazardly, and too ineffectively used in the United States," Pendred E. Noyce writes in the introduction to this volume. "The purpose of this book is to delve into why this is so and how it can be changed." Formative assessment involves constantly monitoring student…

Noyce, Pendred E., Ed.; Hickey, Daniel T., Ed.

2011-01-01

338

Hydride Formation in Zirconium Alloys  

NASA Astrophysics Data System (ADS)

The ingress of hydrogen during corrosion in service can degrade the mechanical properties of zirconium alloy nuclear fuel cladding because of the formation of brittle hydrides. The formation of these hydrides is reviewed in light of recent synchrotron radiation experimental results and phase-field modeling computational results that provide new insight on the process.

Motta, Arthur T.; Chen, Long-Qing

2012-12-01

339

Gene expression regulating blastocyst formation  

Microsoft Academic Search

Development of embryos to the blastocyst stage is a critical event in the early lives of all eutherian mammalian species. Blastocyst formation is essential for implantation and is the principal morphological determinant of embryo quality prior to embryo transfer. The physiological events and roles of specific gene families that regulate blastocyst formation are subjects of intense research. Recent findings have

A. J Watson; M. E Westhusin; P. A De Sousa; D. H Betts; L. C Barcroft

1999-01-01

340

Star formation in the multiverse  

SciTech Connect

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.

Bousso, Raphael; Leichenauer, Stefan [Center for Theoretical Physics, Department of Physics, University of California, Berkeley, California 94720-7300 (United States) and Lawrence Berkeley National Laboratory, Berkeley, California 94720-8162 (United States)

2009-03-15

341

Infrared studies of star formation  

Microsoft Academic Search

Infrared observations at wavelengths of a few microns to 1 mm are reviewed which pertain to the problem of star formation. The data considered include observations of large gas and dust clouds within which stars may be forming and detailed studies of individual objects within these clouds. Stages of star formation are outlined, the IR luminosity of forming stars is

M. W. Werner; E. E. Becklin; G. Neugebauer

1977-01-01

342

Recent star formation in galaxies  

Microsoft Academic Search

In recent years the study of starburst galaxies has become a very popular subject because of their intimate connection with the global star formation history of the Universe. Current estimates of the star formation rate of the Unvierse have been interpreted on the basis of our understanding of local analogous galaxies, in particular through UV continuum and optical line emission.

Alessandro Bressan

2002-01-01

343

Star Formation Through Cosmic Time  

Microsoft Academic Search

I will review the literature on the star formation history of the Universe, from the first stars up to the current day. The first (population III) stars appear to be responsible for the re-ionization of the Universe, and for seeding the inter-galactic medium with heavy elements, facilitating the formation of subsequent generations. There are now many lines of evidence from

Michael A. Dopita

2007-01-01

344

Method for acidizing siliceous formations  

SciTech Connect

A method is described for treating a subterranean formation surrounding a wellbore which comprises injecting into the formation an aqueous acidizing solution. The aqueous acidizing solution contains hydrofluoric acid and excess fluoride. The excess fluoride is present in an amount greater than the amount of fluoride stoichiometrically required to form hydrofluoric acid, and thereafter fluids are produced from the wellbore.

Lamb, W.J.; Kunze, K.R.

1987-03-10

345

Formative Assessment: A Critical Review  

ERIC Educational Resources Information Center

|This paper covers six interrelated issues in formative assessment (aka, "assessment for learning"). The issues concern the definition of formative assessment, the claims commonly made for its effectiveness, the limited attention given to domain considerations in its conceptualisation, the under-representation of measurement principles in that…

Bennett, Randy Elliot

2011-01-01

346

Tubulogenesis during blood vessel formation  

Microsoft Academic Search

The ability to form and maintain a functional system of contiguous hollow tubes is a critical feature of vascular endothelial cells (ECs). Lumen formation, or tubulogenesis, occurs in blood vessels during both vasculogenesis and angiogenesis in the embryo. Formation of vascular lumens takes place prior to the establishment of blood flow and to vascular remodeling which results in a characteristic

Ke Xu; Ondine Cleaver

347

Fast Food Television Advertisement Formats  

Microsoft Academic Search

The purpose of the study was to examine favorite formats in hamburger television advertisements in order to assist companies in effectively communicating with their target audiences and to motivate those audiences to purchase products. The main findings of the study are that college students appear to prefer the special-effects format for presenting hamburgers in television advertisements. In addition, the testimonial

Fang-Yi Lin; Shane C. Blum; Tim Dodd

2002-01-01

348

Method of fracturing subsurface formations  

Microsoft Academic Search

In a method of forming a multilayer pack of rigid, spherical propping agent particles in a fracture in a relatively soft formation, after the formation has been fractured, the faces of the fracture are sealed for only a part of the distance from the well. A liquid carrying the propping agent is then displaced into the fracture whereby the liquid

J. L. Huitt; B. B. McGlothlin

1967-01-01

349

Motivating Students through Formative Feedback  

ERIC Educational Resources Information Center

|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…

Mauch, Lois

2007-01-01

350

Tubulogenesis during blood vessel formation  

PubMed Central

The ability to form and maintain a functional system of contiguous hollow tubes is a critical feature of vascular endothelial cells (ECs). Lumen formation, or tubulogenesis, occurs in blood vessels during both vasculogenesis and angiogenesis in the embryo. Formation of vascular lumens takes place prior to the establishment of blood flow and to vascular remodeling which results in a characteristic hierarchical vessel organization. While epithelial lumen formation has received intense attention in past decades, more recent work has only just begun to elucidate the mechanisms controlling the initiation and morphogenesis of endothelial lumens. Studies using in vitro and in vivo models, including zebrafish and mammals, are beginning to paint an emerging picture of how blood vessels establish their characteristic morphology and become patent. In this chapter, we review and discuss the molecular and cellular mechanisms driving the formation of vascular tubes, primarily in vivo, and we compare and contrast proposed models for blood vessel lumen formation.

Xu, Ke; Cleaver, Ondine

2011-01-01

351

The formation of Pangea  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

352

Significant melting of ice-wedges and formation of thermocirques on hill-slopes of thermokarst lakes in Central Yakutia (Siberia)  

NASA Astrophysics Data System (ADS)

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.

Séjourné, Antoine; Costard, François; Gargani, Julien; Fedorov, Alexander; Skorve, Johnny

2013-04-01

353

Star Formation at z ~ 1  

NASA Astrophysics Data System (ADS)

We propose using FLAMINGOS in MOS mode to obtain near-infrared spectra of ~ 200 GOODS galaxies at z ~ 1, using the 4-m telescope on Kitt Peak. This will, for the first time, provide a sample of sufficient size to allow for a statistically sound analysis of the star formation rate at z ~ 1; a crucial epoch in the star formation history of the Universe. Several controversial issues will be addressed using this dataset. H(alpha), used routinely as a local star formation indicator, will be directly measured in order to determine the global star formation rate at z ~ 1, where many conflicting results exist. Star formation rates derived from the H(alpha) emission will also be used to calibrate star formation derived from existing MIPS 24 (mu) m data, equivalent at z ~ 1 to 12 (mu) m rest frame emission, which is caused by PAHs and warm, small-grain thermal continuum. Finally, star formation estimates from the most commonly used indicators, namely H(alpha), [OII], radio, UV and PAH features, will be compared and assessed. Line ratios from features in the FLAMINGOS near-IR and recently obtained Keck optical spectra will allow for the quantification of extinction and metallicity.

MacDonald, Emily; Dickinson, Mark; Mobasher, Bahram; Allen, Paul; Papovich, Casey

2006-02-01

354

Liquid HEC formation damage potential  

SciTech Connect

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.

Ali, S.A.; Sketchler, B.C. (Chevron USA Production Co., New Orleans, LA (United States)); Hashemi, R. (Pall Corp., East Hills, NY (United States))

1994-11-01

355

Bacteriorhodopsin formation in Halobacterium halobium.  

PubMed

Systematic examinations were made of factors influencing bacteriorhodopsin formation during the growth of Halobacterium halobium. Light-induced adenosine triphosphate (ATP) production and [14C]proline uptake were used as measures of functional ability of the purple membrane. Maximum bacteriorhodopsin formation occurred under growth conditions of illumination and limited aeration. The purple membrane -ATP production system did not confer an appreciable growth advantage. Growth in the dark or with adequate aeration partially suppressed bacteriorhodopsin formation and the effects were additive. Nicotine effectively inhibited bacteriorhodopsin formation. A rapid synthesis of functional pigment occurred when washed suspensions of cells which had been grown under illumination with nicotine present were incubated under dark, aerobic conditions. The alleviation of this nicotine inhibition was not blocked by chloramphenicol or bacitracin. Bacteriorhodopsin formation was negligible when washed suspensions of cells from dark, limited aeration or light, adequate aeration cultures were incubated in the light with limited aeration. A nutritionally complex medium was needed to elicit appreciable bacteriorhodopsin formation by the cells from the dark or adequately aerated cultures. Bacitracin partially inhibited this bacteriorhodopsin formation by cells form the light, adequately aerated culture. PMID:974919

Hubbard, J S; Rinehart, C A

1976-09-01

356

Dissipative processes in galaxy formation.  

PubMed Central

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.

Silk, J

1993-01-01

357

Colloid formation in implanted glasses  

SciTech Connect

Metal colloids in glasses can yield an enhanced ([chi]([sup 3])) susceptibility which leads to an intensity dependent refractive index. Ion implantation is a convenient means of introducing the metal species. The host glass plays an important role in colloid formation. We have characterized Ag-colloid formation in various silicate glasses and, in addition, have studied the formation of colloids in Ag-doped phosphate glass as a function of N and H implantation. Some preliminary results for Cu-implanted glasses are presented.

Arnold, G.W. (Sandia National Labs., Albuquerque, NM (United States)); Mazzoldi, P.; Tramontin, L. (Padua Univ. (Italy)); Boscolo-Boscoletto, A. (ECP-EniChem Polimeri, Porto Marghera (Italy)); Battaglin, G. (Venice Univ. (Italy))

1992-01-01

358

Colloid formation in implanted glasses  

SciTech Connect

Metal colloids in glasses can yield an enhanced ({chi}({sup 3})) susceptibility which leads to an intensity dependent refractive index. Ion implantation is a convenient means of introducing the metal species. The host glass plays an important role in colloid formation. We have characterized Ag-colloid formation in various silicate glasses and, in addition, have studied the formation of colloids in Ag-doped phosphate glass as a function of N and H implantation. Some preliminary results for Cu-implanted glasses are presented.

Arnold, G.W. [Sandia National Labs., Albuquerque, NM (United States); Mazzoldi, P.; Tramontin, L. [Padua Univ. (Italy); Boscolo-Boscoletto, A. [ECP-EniChem Polimeri, Porto Marghera (Italy); Battaglin, G. [Venice Univ. (Italy)

1992-12-31

359

Circumstellar disks and planetary formation  

NASA Astrophysics Data System (ADS)

Circumstellar disks are the the cradle of planetary systems. They are found around a large number of intermediate- and low-mass stellar objects in star forming regions and young clusters. Their study can provide important clues about the timescales and physical conditions for planet formation. In this paper, I review some properties of circumstellar disks that come from the analysis of multi-wavelength observational data, and that are important in the context of planet formation. In addition, I also present the first evidences of planetary formation within the so-called transitional disks.

Huélamo, N.

2013-05-01

360

Dynamics of rock varnish formation  

SciTech Connect

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.

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

1991-01-01

361

Study of the Morrison Formation  

Microsoft Academic Search

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

Charles Craig Mook

1916-01-01

362

Tooth formation - delayed or absent  

MedlinePLUS

Specific diseases can have a profound effect on tooth shape, tooth color, time of appearance, or tooth absence. Delayed or absent tooth formation can result from many different conditions, including: Apert syndrome Cleidocranial dysostosis ...

363

Metamorphism and Metamorphic Formation & Deformation  

NSDL National Science Digital Library

This presentation on metamorphis and metamorphic formation was created by Martin Streck of Portland State University. The lesson provides an overview on the deformation of metamorphic rocks and minerals and includes helpful diagrams and images.

Streck, Martin

2008-04-25

364

XENON TETRAFLUORIDE: HEAT OF FORMATION  

Microsoft Academic Search

Calorimetric measurements of the heat of reaction of xenon tetrafluoride ; with aqueous iodide solution give -- 60 kilocalories per mole for the standard ; heat of formation, or an average thermochemical bond energy of about 31 ; kilocalories. (auth);

S. R. Gunn; S. M. Williamson

1963-01-01

365

The Mechanism of Tornado Formation.  

National Technical Information Service (NTIS)

The mechanism (phases) of a developing tornado was investigated in this study on a laboratory model. Three existing theories for the mechanism of tornado formation were studied and discussed in length. From the information gained in this study an experime...

K. T. Repsholdt

1973-01-01

366

Circadian rhythms and memory formation  

Microsoft Academic Search

There has been considerable progress in elucidating the molecular mechanisms that contribute to memory formation and the generation of circadian rhythms. However, it is not well understood how these two processes interact to generate long-term memory. Recent studies in both vertebrate and invertebrate models have shown time-of-day effects on neurophysiology and memory formation, and have revealed a possible role for

Jason R. Gerstner; Jerry C. P. Yin

2010-01-01

367

Monovacancy formation enthalpy in silicon  

NASA Astrophysics Data System (ADS)

Positron-lifetime experiments have been conducted on silicon at temperatures between 300 and 1523 K. A lifetime attributable to positrons annihilating in monovacancies is directly observed above 1450 K. This lifetime has the same value as that associated with monovacancies at low temperature indicating that the character of the monovacancy is essentially independent of temperature. The results yield an activation enthalpy for neutral monovacancy formation of 3.6+/-0.2 eV. No evidence for divacancy formation could be found.

Dannefaer, S.; Mascher, P.; Kerr, D.

1986-05-01

368

Pellicle formation in Shewanella oneidensis  

Microsoft Academic Search

BACKGROUND: Although solid surface-associated biofilm development of S. oneidensis has been extensively studied in recent years, pellicles formed at the air-liquid interface are largely overlooked. The goal of this work was to understand basic requirements and mechanism of pellicle formation in S. oneidensis. RESULTS: We demonstrated that pellicle formation can be completed when oxygen and certain cations were present. Ca(II),

Yili Liang; Haichun Gao; Jingrong Chen; Yangyang Dong; Lin Wu; Zhili He; Xueduan Liu; Guanzhou Qiu; Jizhong Zhou

2010-01-01

369

The Portable Document Format - PDF.  

PubMed

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

Grech, V

2002-04-01

370

Methane formation in sewer systems  

Microsoft Academic Search

Methane formation and emission in sewer systems has not received as much attention as hydrogen sulphide formation. Through field measurements from two rising mains, with an average sewage temperature of 28.4 and 26.6°C, respectively, at the time of sampling, this study shows that a significant amount of methane can be produced in sewer systems, and that this production is positively

Albert Guisasola; David de Haas; Jurg Keller; Zhiguo Yuan

2008-01-01

371

Aerosol Formation in Photochemical Smog  

Microsoft Academic Search

During operation of smog chambers, the gas mixture is normally well-stirred although the extent of stirring varies from chamber to chamber. Experiments conducted at Battelle’s Columbus Laboratories in a 200-liter and a 610-cu ft smog chamber have shown that stirring can decrease aerosol formation. The faster the chamber contents are stirred the greater the reduction in aerosol formation observed. Sufficiently

Wm. E. Wilson Jr; E. L. Merryman; Arthur Levy; Harold R. Taliaferro

1971-01-01

372

Dense cloud formation and star formation in a barred galaxy  

NASA Astrophysics Data System (ADS)

We investigate the properties of massive, dense clouds formed in a barred galaxy and their possible relation to star formation, performing a two-dimensional hydrodynamical simulation with the gravitational potential obtained from the 2MASS data from the barred spiral galaxy, M83. Since the environment for cloud formation and evolution in the bar region is expected to be different from that in the spiral arm region, barred galaxies are a good target to study the environmental effects on cloud formation and the subsequent star formation. Our simulation uses for an initial 80 Myr isothermal flow of non-self gravitating gas in the barred potential, then including radiative cooling, heating and self-gravitation of the gas for the next 40 Myr, during which dense clumps are formed. We identify many cold, dense gas clumps for which the mass is more than 104 M? (a value corresponding to the molecular clouds) and study the physical properties of these clumps. The relation of the velocity dispersion of the identified clump's internal motion with the clump size is similar to that observed in the molecular clouds of our Galaxy. We find that the virial parameters for clumps in the bar region are larger than that in the spiral arm region. From our numerical results, we estimate star formation in the bar and spiral arm regions by applying the simple model of Krumholz & McKee (2005). The mean relation between star formation rate and gas surface density agrees well with the observed Kennicutt-Schmidt relation. The star formation efficiency in the bar region is ˜60 per cent of the spiral arm region. This trend is consistent with observations of barred galaxies.

Nimori, M.; Habe, A.; Sorai, K.; Watanabe, Y.; Hirota, A.; Namekata, D.

2013-03-01

373

Formate Dehydrogenase from Clostridium acidiurici  

PubMed Central

Partial purification of formate dehydrogenase from Clostridium acidiurici has been accomplished, and some properties of the enzyme have been determined. The molecular weight of the protein is at least 200,000 daltons. The enzyme showed marked instability to freezing and thawing and was inhibited strongly by oxygen and by light. Such inhibition was not reversed by incubation in the presence of thiol compounds. Cyanide inhibited the enzyme 90% at 0.1 mm concentrations, but ethylenediaminetetraacetate produced only slight inhibition at concentrations as high as 50 mm. The purified enzyme showed no ferredoxin activity in the Clostridium pasteurianum clastic system during pyruvate oxidation. Crude preparations of the enzyme could be coupled through ferredoxin to the reduction of nicotinamide adenine dinucleotide during formate oxidation, but the purified enzyme could not catalyze the reduction of pyridine nucleotides by formate in the presence of ferredoxin. Formate oxidation with the purified enzyme was readily coupled to benzyl viologen reduction, in which case ferredoxin was not required. An exchange between formate and bicarbonate was catalyzed by both crude and purified preparations of the enzyme, but the net synthesis of formate from CO2 was not accomplished.

Kearny, James J.; Sagers, Richard D.

1972-01-01

374

Delayed star formation in galaxies  

SciTech Connect

The problem of delayed star formation in galaxies is formulated, and some possible approaches to solving it are discussed. Observational evidence suggests that galaxies undergo long periods (10/sup 8/--10/sup 10/ yr) when star formation is suppressed. Two modes of star formation are considered: 1) gravitational collapse and fragmentation of initially rarefied gas; 2) creation of stars through collisions of interstellar clouds. In these contexts three mechanisms are examined for suppressing star formation, each involving supernova outbursts: a) the gas density in the disk of a galaxy drops below its critical value; b) gravitationally bound fragments are disrupted through heating by external radiation sources (supernovae and supernova remnants); c) the cool interstellar gas phase decays when the heating rate rises above a critical value. Estimates of the heating rate indicate that star formation will be suppressed by mechanisms b and c. If the number of supernovae and supernova remnants was formerly one to three orders of magnitude greater than today, as could have happened in the Galaxy during active evolutionary phases, then star formation could indeed have been suppressed.

Suchkov, A.A.; Shchekinov, Y.A.

1979-11-01

375

Schemes for biased galaxy formation  

SciTech Connect

Three independent schemes are proposed for biasing galaxy formation toward luminous galaxies, early collapse, and denser protogalaxies in a universe containing a closure density of cold dark matter. Photinos, or other massive, neutral weakly interacting leptons are assumed to be the predominant dark matter species, and their annihilation in collapsing protogalactic clouds suppresses galaxy bulge formation for isolated systems. Shock destruction of H2 can occur at low redshift during the epoch of massive galaxy and quasar formation; the ensuing collapse and cooling of primordial clouds by Ly emission results in predominantly massive star formation that should disrupt late-forming galaxies. The high rate of stgar formtion presumed to occur during gaseous protogalaxy collapse effectively strips low-density protogalaxies by initiating a supernova-driven wind, and leaves behind low surface density remnants: ''failed galaxies.'' These schemes could all be complementary, and generally lead to the formation of luminous galaxies by rare, dense, early collapsing systems, luminous galaxy formation being suppressed in the recent past.

Silk, J.

1985-10-01

376

Star formation in colliding and merging galaxies  

Microsoft Academic Search

The process of star formation in interacting galaxies is discussed, reviewing the results of recent observational and theoretical investigations. Topics examined include the general characteristics of starburst galaxies, the spatial distribution of star formation, the mechanisms governing the formation of molecular gas, star-formation rates, star-formation efficiency, and initial mass functions. It is suggested that galactic collisions or mergers may lead

Francois Schweizer

1987-01-01

377

Microtiter dish biofilm formation assay.  

PubMed

Biofilms are communities of microbes attached to surfaces, which can be found in medical, industrial and natural settings. In fact, life in a biofilm probably represents the predominate mode of growth for microbes in most environments. Mature biofilms have a few distinct characteristics. Biofilm microbes are typically surrounded by an extracellular matrix that provides structure and protection to the community. Microbes growing in a biofilm also have a characteristic architecture generally comprised of macrocolonies (containing thousands of cells) surrounded by fluid-filled channels. Biofilm-grown microbes are also notorious for their resistance to a range of antimicrobial agents including clinically relevant antibiotics. The microtiter dish assay is an important tool for the study of the early stages in biofilm formation, and has been applied primarily for the study of bacterial biofilms, although this assay has also been used to study fungal biofilm formation. Because this assay uses static, batch-growth conditions, it does not allow for the formation of the mature biofilms typically associated with flow cell systems. However, the assay has been effective at identifying many factors required for initiation of biofilm formation (i.e, flagella, pili, adhesins, enzymes involved in cyclic-di-GMP binding and metabolism) and well as genes involved in extracellular polysaccharide production. Furthermore, published work indicates that biofilms grown in microtiter dishes do develop some properties of mature biofilms, such a antibiotic tolerance and resistance to immune system effectors. This simple microtiter dish assay allows for the formation of a biofilm on the wall and/or bottom of a microtiter dish. The high throughput nature of the assay makes it useful for genetic screens, as well as testing biofilm formation by multiple strains under various growth conditions. Variants of this assay have been used to assess early biofilm formation for a wide variety of microbes, including but not limited to, pseudomonads, Vibrio cholerae, Escherichia coli, staphylococci, enterococci, mycobacteria and fungi. In the protocol described here, we will focus on the use of this assay to study biofilm formation by the model organism Pseudomonas aeruginosa. In this assay, the extent of biofilm formation is measured using the dye crystal violet (CV). However, a number of other colorimetric and metabolic stains have been reported for the quantification of biofilm formation using the microtiter plate assay. The ease, low cost and flexibility of the microtiter plate assay has made it a critical tool for the study of biofilms. PMID:21307833

O'Toole, George A

2011-01-30

378

Microtiter Dish Biofilm Formation Assay  

PubMed Central

Biofilms are communities of microbes attached to surfaces, which can be found in medical, industrial and natural settings. In fact, life in a biofilm probably represents the predominate mode of growth for microbes in most environments. Mature biofilms have a few distinct characteristics. Biofilm microbes are typically surrounded by an extracellular matrix that provides structure and protection to the community. Microbes growing in a biofilm also have a characteristic architecture generally comprised of macrocolonies (containing thousands of cells) surrounded by fluid-filled channels. Biofilm-grown microbes are also notorious for their resistance to a range of antimicrobial agents including clinically relevant antibiotics. The microtiter dish assay is an important tool for the study of the early stages in biofilm formation, and has been applied primarily for the study of bacterial biofilms, although this assay has also been used to study fungal biofilm formation. Because this assay uses static, batch-growth conditions, it does not allow for the formation of the mature biofilms typically associated with flow cell systems. However, the assay has been effective at identifying many factors required for initiation of biofilm formation (i.e, flagella, pili, adhesins, enzymes involved in cyclic-di-GMP binding and metabolism) and well as genes involved in extracellular polysaccharide production. Furthermore, published work indicates that biofilms grown in microtiter dishes do develop some properties of mature biofilms, such a antibiotic tolerance and resistance to immune system effectors. This simple microtiter dish assay allows for the formation of a biofilm on the wall and/or bottom of a microtiter dish. The high throughput nature of the assay makes it useful for genetic screens, as well as testing biofilm formation by multiple strains under various growth conditions. Variants of this assay have been used to assess early biofilm formation for a wide variety of microbes, including but not limited to, pseudomonads, Vibrio cholerae, Escherichia coli, staphylocci, enterococci, mycobacteria and fungi. In the protocol described here, we will focus on the use of this assay to study biofilm formation by the model organism Pseudomonas aeruginosa. In this assay, the extent of biofilm formation is measured using the dye crystal violet (CV). However, a number of other colorimetric and metabolic stains have been reported for the quantification of biofilm formation using the microtiter plate assay. The ease, low cost and flexibility of the microtiter plate assay has made it a critical tool for the study of biofilms.

O'Toole, George A.

2011-01-01

379

The history of star formation in bulges  

Microsoft Academic Search

Nearby bulge\\/E systems are examined with existing star-formation data to determine when active star formation occurred in relation to globular cluster formation. Two scenarios of bulge history are contrasted including the classical notion by O'Connell (1958) and the notion of an extended period of star formation. Spectroscopic data regarding recent star formation are examined as are data on formation of

Robert W. O'Connell

1990-01-01

380

Star Formation in Atomic Gas  

NASA Astrophysics Data System (ADS)

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 H2-regulated star formation may need to be modified.

Krumholz, Mark R.

2012-11-01

381

Physicochemical regulation of biofilm formation  

PubMed Central

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.

Renner, Lars D.; Weibel, Douglas B.

2011-01-01

382

Formation of the serine octamer  

NASA Astrophysics Data System (ADS)

The mechanism of formation for clusters of serine generated by electrospray ionization is hypothesized to play a critical role in determining their ultimate properties. Under carefully manipulated electrospray source conditions, two distinct and well-separated distributions of clusters can be observed. The characteristics of the two cluster populations are consistent with different formation mechanisms, namely ion evaporation and charge residue. Upon further inspection, it is proposed that the magic number intensity, homochiral selectivity, and unique formation of the serine octamer are best explained within the context of the ion evaporation mechanism. As a consequence, solution phase properties of the octamer become important, particularly in relation to interface effects present on the surface of the charged droplet. In contrast, other clusters of serine, including the B form of the octamer, are probably generated by the charge residue mechanism and may have no connection to condensed phase phenomena.

Spencer, Emily A. C.; Ly, Tony; Julian, Ryan R.

2008-03-01

383

Jet-Induced Star Formation  

SciTech Connect

Jets from radio galaxies can have dramatic effects on the medium through which they propagate. We review observational evidence for jet-induced star formation in low ('FR-I') and high ('FR-II') luminosity radio galaxies, at low and high redshifts respectively. We then discuss numerical simulations which are aimed to explain a jet-induced starburst ('Minkowski's Object') in the nearby FR-I type radio galaxy NGC 541. We conclude that jets can induce star formation in moderately dense (10 cm{sup -3}), warm (10{sup 4} K) gas; that this may be more common in the dense environments of forming, active galaxies; and that this may provide a mechanism for 'positive' feedback from AGN in the galaxy formation process.

van Breugel, W; Fragile, C; Anninos, P; Murray, S

2003-12-16

384

A New Spoke Formation Model  

NASA Astrophysics Data System (ADS)

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.

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

385

Formation of Planets around Pulsars  

NASA Astrophysics Data System (ADS)

Pulse arrival-time delays PSR 1257+ 12 suggest the existence of at least two planets in nearly circular orbits around it. In this paper we discuss different scenarios for the formation of planets in circular orbits around pulsars. Among other topics, we look in some detail at wind emission mechanisms that are particularly relevant to the process of evaporation of planets around pulsars and discuss their possible role in orbit circularization. We conclude that the formation of such planets may occur in a very late phase of low-mass X-ray binary (LMXB) or binary millisecond pulsar (BMP) evolution. Evaporation of the companion star in these phases supplies matter to a circumbinary "excretion" disk in which the physical conditions, similar to those appropriate for the BMP 1957+20 system, may allow the formation of planets like those observed in PSR 1257+12.

Banit, M.; Ruderman, M. A.; Shaham, J.; Applegate, J. H.

1993-10-01

386

Formation design and nonlinear control of spacecraft formation flying  

Microsoft Academic Search

The fundamental control challenges associated with Spacecraft Formation Flying (SFF) can be classified into two categories: (i) trajectory design and (ii) trajectory tracking. In this research, we address these challenges for several different operating environments. The first part of this research focuses on providing a trajectory generation and an adaptive control design methodology to facilitate SFF missions near the Sun-Earth

Hong Wong

2006-01-01

387

Formation of the first stars  

NASA Astrophysics Data System (ADS)

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.

Bromm, Volker

2013-11-01

388

Pattern Formation in Active Fluids  

NASA Astrophysics Data System (ADS)

We discuss pattern formation in active fluids in which active stress is regulated by diffusing molecular components. Nonhomogeneous active stress profiles create patterns of flow which transport stress regulators by advection. Our work is motivated by the dynamics of the actomyosin cell cortex in which biochemical pathways regulate active stress. We present a mechanism in which a single diffusing species up regulates active stress, resulting in steady flow and concentration patterns. We also discuss general pattern-formation behaviors of reaction-diffusion systems placed in active fluids.

Bois, Justin S.; Jülicher, Frank; Grill, Stephan W.

2011-01-01

389

Initial phase of protostar formation  

NASA Astrophysics Data System (ADS)

Observational data on an active star formation region in the dense molecular cloud Orion KL in the form of H2O maser emission are analyzed in terms of a hydrodynamic whirlwind mechanism for the excitation of bipolar outflows from the disk system. The whirlwind theory for the excitation of bipolar flows from the disk system is found to provide a first order approximation for explaining the major observed features of the active region and the structure accompanying the formation of a protostar: a disk-bipolar flow, including the mechanism by which it is ejected and autocollimated, and the excitation of maser radiation.

Abrahamyan, M. G.; Matveenko, L. I.

2012-09-01

390

Myotome formation: a multistage process  

Microsoft Academic Search

The epaxial muscles of the body are localized in a dorsomedial position with respect to the axial structures, attach to the vertebral column and are concerned with maintenance of posture and movements of the vertebral column. The epaxial musculature derives from the myotome, a transient embryonic structure whose formation is initiated at the epithelial somite stage and is accomplished following

Chaya Kalcheim; Yuval Cinnamon; Nitza Kahane

1999-01-01

391

Identity Formation: Discovery or Creation?  

Microsoft Academic Search

The contrasting metaphors of discovery and creation are proposed here as alternative ways of understanding the nature of the task of identity formation. These two metaphors are related to the philosophies of eudaimonisn and existentialism, respectively. The processes of discovery and creation are shown to have distinctive theoretical implications regarding (a) the sources of identity elements, (b) the methods used

Alan S. Waterman

1984-01-01

392

Large-format imaging system  

Microsoft Academic Search

Bechtel Nevada, in collaboration with Los Alamos National Laboratory, has designed a radiographic imaging system that takes advantage of large format electron optical elements to produce a highly sensitive system for large diameter radiographic fluxes. Using specially designed fast lenses, the system is able to observe scintillator screens as large as 300 mm in diameter.A gated microchannel plate intensifier allows

Stuart A. Baker; Lawrence J. Castellano; Paul A. Flores; Brent C. Frogget; Wilfred Lewis; Paul T. Nedrow; John S. Rohrer; Nicholas S. King

1997-01-01

393

QGP formation and strange antibaryons  

Microsoft Academic Search

We explore, as function of the collision energy and stopping in relativistic nuclear collisions, the production yields of strange antibaryons, assuming formation of a deconfined thermal quark-gluon plasma (QGP) fireball which undergoes a sudden hadronisation. Aside of assumptions related to this reaction picture and QCD properties at this energy scale, our work does not contain (fitted) parameters.

Jean Letessier; Johann Rafelski; Ahmed Tounsi

1997-01-01

394

Formation and Composition of Planetesimals  

Microsoft Academic Search

The composition of planetesimals depends upon the epoch and the location of their formation in the solar nebula. Meteorites produced in the hot inner nebula contain refractory compounds. Volatiles were present in icy planetesimals and cometesimals produced in the cold outer nebula. However, the mechanism responsible for their trapping is still controversial. We argue for a general scenario valid in

Daniel Gautier; Franck Hersant

2005-01-01

395

Junction formation during desiccation cracking  

NASA Astrophysics Data System (ADS)

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.

Toga, K. B.; Alaca, B. Erdem

2006-08-01

396

Junction formation during desiccation cracking.  

PubMed

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. PMID:17025423

Toga, K B; Alaca, B Erdem

2006-08-09

397

Geochemistry: Leftovers from core formation  

NASA Astrophysics Data System (ADS)

Late addition of meteoric material to the Earth's mantle could explain the presence of iron-loving elements that should have entered the Earth's core at its formation. But experiments at realistic conditions show that enough palladium could have remained in the mantle.

Marty, Bernard

2008-05-01

398

Group formation and voter participation  

Microsoft Academic Search

We present a model of participation in large elections in which the formation of voter groups is endogenous. Partisan citizens decide whether to become lead- ers (activists) and try to persuade impressionable citizens to vote for the leaders' preferred party. In the (unique) pure strategy equilibrium, the number of lead- ers favoring each party depends on the cost of activism

HELIOS HERRERA; CÉSAR MARTINELLI

2004-01-01

399

INTERCHANGE FORMATS FOR SPATIAL AUDIO  

Microsoft Academic Search

Space has been a central parameter in electroacoustic music composition and performance since its origins. Nevertheless, the design of a standardized interchange format for spatial audio performances is a complex task that poses a diverse set of constraints and problems. This position paper attempts to describe the current state of the art in terms of what can be called \\

Stephen Travis Pope

400

Formation of the Giant Planets  

Microsoft Academic Search

The structure of a gaseous envelope surrounding a protoplanet has been investigated in connection with the formation of the giant planets. Under the assumptions of spherical symmetry and hydrostatic equilibrium, the structure has been calculated for the regions of Jupiter, Saturn, Uranus and Neptune. Energy transfer in the envelope has been taken into account precisely. When the core mass increases

Hiroshi Mizuno

1980-01-01

401

Implications for Popular Streaming Formats  

Microsoft Academic Search

With the proliferation of mobile streaming multimedia, available bat- tery capacity constrains the end-user experience. Since streaming applications tend to be long running, wireless network interface card's (WNIC) energy consumption is particularly an acute problem. In this work, we explore various mechanisms to conserve client WNIC energy consumption for popular streaming formats such as Microsoft Windows media, Real and Apple

Surendar Chandra

402

The formation of incense smoke  

Microsoft Academic Search

The formation of incense smoke generated from four different types of incense sticks, three manufactured in Taiwan and one in Japan, was investigated in a small controlled chamber. The scanning mobility particle sizer and the quartz crystal microbalance were used for particle size analyses. The count median diameter (CMD) was found to rise swiftly along the path of the incense

Yu-Chen Chang; Hsiu-Wei Lee; Huan-Hsiung Tseng

2007-01-01

403

Pattern formation outside of equilibrium  

Microsoft Academic Search

A comprehensive review of spatiotemporal pattern formation in systems driven away from equilibrium is presented, with emphasis on comparisons between theory and quantitative experiments. Examples include patterns in hydrodynamic systems such as thermal convection in pure fluids and binary mixtures, Taylor-Couette flow, parametric-wave instabilities, as well as patterns in solidification fronts, nonlinear optics, oscillatory chemical reactions and excitable biological media.

M. C. Cross; P. C. Hohenberg

1993-01-01

404

Star formation triggered by interactions  

Microsoft Academic Search

The fact that galaxy interactions can trigger major starbursts is nicely exemplified by nearby interacting and merging galaxies, such as the Antennae. Interaction processes have been more common and thus more important at large lookback times, when galaxies assembled through mergers and interactions. At high redshift, we can currently only trace the most luminous mergers, resulting in star formation rates

F. Walter

2005-01-01

405

Biofilm formation in Streptococcus pneumoniae.  

PubMed

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

Domenech, Mirian; García, Ernesto; Moscoso, Miriam

2011-09-09

406

Struvite formation, control and recovery  

Microsoft Academic Search

Recent legislation on the removal of nutrients from wastewater has led to a number of operation problems with struvite scaling. Struvite is MgNH4PO4·6H2O and this paper reviews the formation, control and recovery of struvite from primarily municipal wastewater and other waste streams. Treatment options for control and technologies for recovery are discussed.

James D Doyle; Simon A Parsons

2002-01-01

407

Extraposition via Complex Domain Formation  

Microsoft Academic Search

We propose a novel approach to extraposition in German within an alternative conception of syntax in which syntactic structure and linear order are mediated not via encodings of hierarchical relations but instead via order domains. At the heart of our proposal is a new kind of domain formation which affords analyses of extraposition constructions that are linguistically more adequate than

Andreas Kathol; Carl Pollard

1995-01-01

408

Salesperson impression and strategy formation  

Microsoft Academic Search

Personal selling is one of the most expensive, and for many companies, one of the most important elements of the marketing mix. Salesperson adaptivity is an especially important element of salesperson performance. The purpose of this research was to explore factors that may influence salespersons' adaptivity during the impression-formation and strategy formulation stages of the selling process. We found that

Elizabeth H. Creyer; William T. Ross

1994-01-01

409

Amyloid Beta Mediates Memory Formation  

ERIC Educational Resources Information Center

|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,…

Garcia-Osta, Ana; Alberini, Cristina M.

2009-01-01

410

Sandbar Formation Under Surface Waves  

Microsoft Academic Search

We report a combined theoretical and experimental study of sandbar formation under simple-harmonic surface waves. For coarse grains and weak waves, an established empirical rule of bedload transport is used with an asymptotic theory for the fluid flow. The surface waves are governed by potential theory and a depth-linear eddy viscosity is employed in the turbulent boundary layer at the

M. J. Hancock; B. J. Landry; C. C. Mei

2007-01-01

411

Tourism motivation and expectation formation  

Microsoft Academic Search

This theoretical study introduces a model of tourism motivation and expectation formation. It is based on a discussion and operationalization of both the behaviorist notion of drive reduction and the cognitivist constructs of attitudes and values. While the satisfaction of inner-directed values and motivations depends on classes of objects, outer-directed values target specific objects. In the case of trying to

Juergen Gnoth

1997-01-01

412

Geometric Cooperative Control of Formations.  

National Technical Information Service (NTIS)

Robots in a team are modeled as particles which obey simple, second order dynamics. The whole team can be viewed as a deformable body with changing shape and orientation. Jacobi shape theory is applied to model such a formation. The configuration space of...

F. Zhang

2004-01-01

413

Stereotype Formation: Biased by Association  

ERIC Educational Resources Information Center

|We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

2010-01-01

414

Stereotype Formation: Biased by Association  

ERIC Educational Resources Information Center

We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

2010-01-01

415

Formation of Supermassive Black Holes  

Microsoft Academic Search

Three different proposed mechanisms for supermassive black hole (SMBH) formation have been presented. Firstly, it has been suggested that SMBHs form in galactic nuclei by coherent collapse. Secondly, it has been suggested that SMBHs form by stellar collapse and then grow in mass. A third scenario is that massive black holes have a primordial origin and then grow in mass

Selig Kainer; William K. Rose

2003-01-01

416

A standard audit trail format  

SciTech Connect

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.

Bishop, M. [Univ. of California, Davis, CA (United States). Dept. of Computer Science

1995-02-01

417

MILLED RICE FISSURE FORMATION KINETICS  

Microsoft Academic Search

Milled rice samples at various moisture contents (MCs) were exposed to air inside a chamber that was equipped with a video camera and monitoring system that enabled observation of fissure formation over a 24-h exposure duration. The effects of milled rice kernel MC (11%, 12%, 13%, or 14%), cultivar (Bengal, Wells, and CL161), air relative humidity (RH; 10%, 20%, 30%,

T. J. Siebenmorgen; M. I. Saleh; R. C. Bautista

418

Technologies for Spacecraft Formation Flying  

Microsoft Academic Search

Differential carrier phase GPS for orbit and attitude determination is emerging as a very promising low cost alternative to more conventional methods, such as horizon sensors, sun sensors, magnetometers, and star trackers. Relative spacecraft position and attitude determination are important for missions involving formation flying, such as those proposed for stellar interferometry under NASA's New Millennium Program, and LEO missions

John Adams; Andrew Robertson; Kurt Zimmerman

1996-01-01

419

The Theory of Planetary Formation  

NSDL National Science Digital Library

This website offers an audio of a lecture on the theory of planetary formation. There is also an option to use a viewgraph if you do not have real audio player. The site also provides a detailed written summary of the audio lecture.

Cassen, Patrick

2005-04-25

420

Increasing permeability of subsurface formations  

Microsoft Academic Search

This is a method of increasing permeability of a fractured formation to fluid flow by depositing in the fractures a single layer or less of solid particle-form, propping agents of preselected size and strength. A large volume of nonpenetrating fluid which has been treated to control leakoff is injected to lenghten and seal the fracture walls. Conventional size sand is

W. J. Jr. McGuire; L. R. Kern

1965-01-01

421

Alliance formation and national security  

Microsoft Academic Search

The premise that nations form alliances in order to improve their security is widespread in the study of international relations. Yet in spite of the crucial role played by this assumption, the claims of policy makers and statesmen form our only evidence that it is the need for greater national security which motivates the formation of alliances. What is more,

David Lalman; David Newman

1991-01-01

422

CCF: The Common Communication Format.  

ERIC Educational Resources Information Center

The purpose of the Common Communication Format (CCF) is to provide a detailed and structured method for recording a number of mandatory and optional data elements in a computer-readable bibliographic record for exchange purposes between two or more computer-based systems. However, it can also be useful within non-computerized bibliographic…

Simmons, Peter, Ed.; Hopkinson, Alan, Ed.

423

Formation of (exo-)planets  

NASA Astrophysics Data System (ADS)

In this small review I will address three recent topics in the field of theoretical planet formation studies. This review is not meant to be complete in any way. It is meant to give an idea where some of the recent developments are.

Dullemond, C. P.

2013-06-01

424

Sedimentary pyrite formation: An update  

NASA Astrophysics Data System (ADS)

Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals. Organic matter appears to be the major control on pyrite formation in normal (non-euxinic) terrigenous marine sediments where dissolved sulfate and iron minerals are abundant. By contrast, pyrite formation in non-marine, freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic-rich fresh water shales from marine shales. Under marine euxinic conditions sufficient H 2S is produced that the dominant control on pyrite formation is the availability of reactive iron minerals. Calculations, based on a sulfur isotope model, indicate that over Phanerozoic time the worldwide average organic carbon-to-pyrite sulfur ratio of sedimentary rocks has varied considerably. High C/S ratios during Permo-Carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time. Low C/S ratios, compared to today, during the early Paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean. The latter could have been due to lower oceanic oxygen levels and/or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time.

Berner, Robert A.

1984-04-01

425

Ultrafast Dynamics of Polaron Formation  

NASA Astrophysics Data System (ADS)

The formation of localized electronic states reflects the fundamental physics of coupling between electronic and lattice dynamics, as first noted by Landau who in 1933 described the process of polaron formation as ``the electron `digs its own hole' and is trapped there.'' Localization of electronic states plays a critical role in determining the properties of a wide range of materials: polaron formation has a profound impact on charge transport properties of electronic materials, and formation of self-trapped excitons, or exciton-polarons, dramatically changes optical properties and energy transport mechanisms. I will present femtosecond time-resolved studies of the dynamics of the localization process, focusing on the formation and evolution of self-trapped excitons and polarons. The experiments are carried out in quasi-one-dimensional materials in which the strength of the electron-phonon coupling that drives the dynamics can be systematically tuned by varying the material composition. Experiments using femtosecond vibrationally impulsive excitation, in which the system is excited with an optical pulse short compared to the periods of the relevant vibrational modes, allow us to time-resolve the coupled electronic and lattice dynamics as the system evolves from the initially photoexcited delocalized electronic state to form a self-trapped exciton, revealing rapid dynamics involving both optical and acoustic phonon modes. Polaron dynamics are probed using time-resolved terahertz spectroscopy, in which short pulses of far-infrared light are used to monitor the fast photoinduced carrier response, and show localization on the time scale of a single vibrational period of the lattice.

Dexheimer, Susan

2012-10-01

426

Controlling factors for global star formation  

Microsoft Academic Search

Here I attempt to address the question: What do we know, or can we know, about the controlling factors for global star formation? First, I open with a very brief review of measurements of current star formation rates. While absolute estimates of current star formation rates carry a significant degree of uncertainty, the comparison of current star formation rates has

Evan D. Skillman

1997-01-01

427

Method of fracturing a geological formation  

DOEpatents

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.

Johnson, James O. (2679-B Walnut, Los Alamos, NM 87544)

1990-01-01

428

Rapid Formation Of Saturn Induced By Jupiter Formation  

NASA Astrophysics Data System (ADS)

We have investigated Saturn's core formation at a radial pressure maximum in the solar nebula, which is created by gap opening by Jupiter. A large core induces collisional fragmentation of surrounding planetesimals, which generally inhibits further growth of the core by removal of the resultant fragments due to radial drift caused by gas drag. However, the emergence of the pressure maximum halts the drift of the fragments, while their orbital eccentricities and inclinations are efficiently damped by gas drag. As a result, the core of Saturn rapidly grows via accretion of the fragments near the pressure maximum. We have found that in the minimum-mass solar nebula, kilometer sized planetesimals can produce a core larger than 10 Earth masses within two million years. Since Jupiter may not have undergone significant type II inward migration, it is likely that Jupiter's formation was completed when the local disk mass has already decayed to a value comparable to or less than Jovian mass. The expected rapid growth of Saturn's core on a timescale comparable to or shorter than observationally inferred disk lifetime enables Saturn to acquire the current amount of envelope gas before the disk gas is completely depleted. The high heat energy release rate onto the core surface due to the rapid accretion of the fragments delays onset of runaway gas accretion until the core mass becomes somewhat larger than that of Jupiter, which is consistent with the estimate based on interior modeling. Therefore, the rapid formation of Saturn induced by gap opening of Jupiter can account for the formation of multiple gas giants (Jupiter and Saturn) without significant inward migration and larger core mass of Saturn than that of Jupiter.

Kobayashi, Hiroshi; Ormel, C. W.; Ida, S.

2012-10-01

429

Biofilm Formation Biofilm Formation Biofilm Formation .EW#LUESIN5NDERSTANDING  

Microsoft Academic Search

he water industry has long been plagued by the effects of biofilm formation in water supplies, pipes, fittings and filters. Such biomasses lead to adverse taste, odor and possible health effects in the water and decrease the life of treatment equipment. Scientists are just beginning to solve the mystery of how and why biofilms form. New evidence indicates that microorganisms

Kelly A. Reynolds

2008-01-01

430

Radio galaxies and galaxy formation  

NASA Astrophysics Data System (ADS)

Radio galaxies at large redshift constrain galaxy formation models in two ways: (1) through their comoving density; (2) through the ages of their stellar population. The observed density of radio galaxies at z roughly 4 sets important limits on power-spectrum normalization in hierarchical models. CDM models probably require a low degree of bias to survive. The 'alignment effect' has been used to argue that observed high-z radio galaxies are young objects in which the majority of stars are generated by the jets from the AGN. However, new data show that alignments are confined to sources of the most extreme radio power. It therefore seems likely that the stellar populations in high-z radio galaxies are old - as expected in hierarchical models for galaxy formation.

Peacock, John

431

Spontaneous protoplast formation in Methanobacterium  

SciTech Connect

Methanobacterium bryantii was found to undergo rapid lysis when grown in a prereduced chemically defined medium under H/sub 2/-CO/sub 2/ (4:1, vol/vol). The addition of 20 mM MgCl/sub 2/ to the medium gave, rather than rapid lysis, a gradual formation of phase-dark spherical bodies which in thin section appeared as true protoplasts. In general, the protoplasts were stabilized by divalent but not monovalent cations and, unlike whole cells, were sensitive to lysis by Triton X-100. Electron microscopic examination revealed that protoplast formation was preceded by a general breakdown of the cell wall with an apparent squeezing out of the protoplast through the degraded wall. The growth of cells was greatly increased and not accompanied by detectable lysis in a medium modified by elevating the levels of nickel and ammonium.

Jarrell, K.F.; Colvin, J.R.; Sprott, G.D.

1982-01-01

432

Porous silicon formation and electropolishing  

NASA Astrophysics Data System (ADS)

Electrochemical etching of silicon in hydrofluoride containing electrolytes leads to pore formation for low and to electropolishing for high applied current. The transition between pore formation and polishing is accompanied by a change of the valence of the electrochemical dissolution reaction. The local etching rate at the interface between the semiconductor and the electrolyte is determined by the local current density. We model the transport of reactants and reaction products and thus the current density in both, the semiconductor and the electrolyte. Basic features of the chemical reaction at the interface are summarized in the law of mass-action-type boundary conditions for the transport equations at the interface. We investigate the linear stability of a planar and flat interface. Upon increasing the current density the stability flips either through a change of the valence of the dissolution reaction or by a nonlinear boundary condition at the interface.

Rauscher, Markus; Spohn, Herbert

2001-09-01

433

CEA Studies on Halo Formation  

NASA Astrophysics Data System (ADS)

Beginning with the TRISPAL project, halo formation has been extensively studied at CEA last 10 years. Effect of mismatching, non-linear forces, resonances, longitudinal-transverse coupling, intrabeam scattering, and interaction with the residual gas have been explored. They have been studied theoretically from both analytical models and dedicated simulation codes and, for some of them, experimentally from proton beam profile measurements over a high dynamic range in a 26 periods FODO channel. Our knowledge, strongly improved through collaborations with our worldwide colleagues, has been applied to the design of several linac projects, whose last are SPIRAL2 and RX2. The goal of this presentation is to summarise the contribution of the CEA teams to the understanding of the halo formation.

Pichoff, N.; Beauvais, P.-Y.; Duperrier, R.; Haouat, G.; Lagniel, J.-M.; Uriot, D.

2003-12-01

434

Engineering biofilm formation and dispersal  

PubMed Central

Anywhere water is in the liquid state, bacteria will exist as biofilms, which are complex communities of cells cemented together. Although frequently associated with disease and biofouling, biofilms are also important for engineering applications, such as bioremediation, biocatalysis and microbial fuel cells. Here we review approaches to alter genetic circuits and cell signaling toward controlling biofilm formation, and emphasize utilizing these tools for engineering applications. Based on a better understanding of the genetic basis of biofilm formation, we find that biofilms may be controlled by manipulating extracellular signals and that they may be dispersed using conserved intracellular signals and regulators. Biofilms could also be formed at specific locations where they might be engineered to make chemicals or treat human disease.

Wood, Thomas K.; Hong, Seok Hoon; Ma, Qun

2011-01-01

435

GSK-3? and memory formation.  

PubMed

In Alzheimer's disease (AD), tau hyperphosphorylation and neurofibrillary tangle (NFT) formation are strongly associated with dementia, a characteristic and early feature of this disease. Glycogen synthase kinase 3? (GSK-3?) is a pivotal kinase in both the normal and pathological phosphorylation of tau. In the diseased state, hyperphosphorylated tau is deposited in NFTs, the formation of which, drive the disease process. GSK-3? which is also involved in long-term depression induction, interacts with tau to inhibit synaptic long-term potentiation. Strong lines of evidence suggest that the activation of GSK-3? is responsible for the memory deficits seen in both advanced age and AD. In this review, we will focus on the role of GSK-3? in brain function, particularly in memory maintenance. We will examine human and mouse studies which suggest a role for GSK-3? in memory maintenance and the eventual development of memory deficits. PMID:22536172

Takashima, Akihiko

2012-04-23

436

Method of fracturing subsurface formations  

SciTech Connect

A method is described of fracturing a subsurface formation which is traversed by a borehole comprising: positioning within the borehole a quantity of a first composition which includes a mixture of a propellant and a granular propping agent, the first composition as positioned forming a first section; positioning a second composition, which includes a propellant, in the borehole so as to occupy a volume separate from and closely adjacent to that volume occupied by the first composition. The second composition as so positioned forms a second section; the first and second sections being positioned in the borehole by introducing the first and second compositions simultaneously into the borehole; igniting the first composition and the second composition to form multiple fissures radiating from the borehole into the formation.

Broade, R.R.

1987-05-05

437

Galaxy Formation: Feedback from Supernovae  

NASA Astrophysics Data System (ADS)

We simulate the collapse of a spherically symmetric proto-galaxy with a SPH/N-body code for a non-rotating, inhomogeneous initial density profile. We include dark matter, (cooling) gas, star formation and energy feedback from supernovae. An energy of 1051 ergs per supernova is deposited in the gas as thermal energy, but this does not significantly alter the dynamics of the collapse, as radiative losses are efficient.

Hartmann, Dieter H.; Myers, Jeannette M.; The, Lih-Sin

438

Formation and Composition of Planetesimals  

Microsoft Academic Search

The composition of planetesimals depends upon the epoch and the location of their formation in the solar nebula. Meteorites\\u000a produced in the hot inner nebula contain refractory compounds. Volatiles were present in icy planetesimals and cometesimals\\u000a produced in the cold outer nebula. However, the mechanism responsible for their trapping is still controversial. We argue\\u000a for a general scenario valid in

Daniel Gautier; Franck Hersant

439

Network formation under linking constraints  

NASA Astrophysics Data System (ADS)

We study the effects of linking constraints on stability, efficiency and network formation. An exogenous "link-constraining system" specifies the admissible links. It is assumed that each player may initiate links only with players within a specified set of players, thus restricting the feasible strategies and networks. In this setting, we examine the impact of such constraints on stable/efficient architectures and on dynamics.

Olaizola, Norma; Valenciano, Federico

2013-10-01

440

C=C Bond Formation  

NASA Astrophysics Data System (ADS)

The material presented in this chapter describes the general methodology used for the preparation of unsaturated sugars. The `older' methods (i. e. those being developed since at least the 1950s) which are still very useful and have general application are also presented but they are illustrated by newer examples. The direct formation of the double bond(s) is emphasized, but the methodology based on the rearrangement of unsaturated sugars into other olefinic carbohydrates is also reviewed.

Jarosz, S?awomir; Nowogródzki, Marcin

441

Interface formation during spinodal decomposition  

SciTech Connect

Already Swanger, Gupta, and Cooper have shown that the nonlinear term in the differential equation that describes spinodal decomposition is responsible for the decomposition going to completion. We contend that the term is also responsible for the decomposition going to completion. We contend that the term is also responsible for the formation of sharp interfaces relatively early in the decomposition process. There is experimental verification of this.

Williams, R.O.

1981-01-01

442

Biofilm formation on oral piercings  

Microsoft Academic Search

Summary  PURPOSE: Biofilms on oral piercings might serve as a bacterial reservoir in the host and lead to bacteraemia and even septic\\u000a complications. The use of piercing materials less susceptible to biofilm accumulation could contribute to alleviation of problems.\\u000a The present study aimed to assess biofilm formation on four commercially available, surface characterized piercing materials\\u000a in vitro (polytetrafluoroethylene, titanium, stainless steel,

Ines Kapferer; Christoph Steiner; Ulrike Beier; Natalia Schiefermeier; Markus Nagl; Frederik Klauser

2010-01-01

443

Crystal sedimentation and stone formation  

Microsoft Academic Search

Mechanisms of crystal collision being the first step of aggregation (AGN) were analyzed for calcium oxalate monohydrate (COM)\\u000a directly produced in urine. COM was produced by oxalate titration in urine of seven healthy men, in solutions of urinary macromolecules\\u000a and in buffered distilled water (control). Crystal formation and sedimentation were followed by a spectrophotometer and analyzed\\u000a by scanning electron microscopy.

Johannes Markus Baumann; Beat Affolter; Rolf Meyer

2010-01-01

444

Method for fracturing subterranean formations  

SciTech Connect

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.

Almond, S. W.; Conway, M. W.

1985-11-19

445

Spray formation with complex fluids  

NASA Astrophysics Data System (ADS)

Droplet formation through Faraday excitation has been tested in the low driving frequency limit. Kerosene was used to model liquid fuel with the addition of PIB in different proportions. All fluids were characterized in detail. The mechanisms of ejection were investigated to identify the relative influence of viscosity and surface tension. It was also possible to characterize the type of instability leading to the emission drop process.

Lustig, S.; Rosen, M.

2011-05-01

446

Union formation in fragile families  

Microsoft Academic Search

In this article, we use data from a new longitudinal survey—the Fragile Families and Child Wellbeing Study—to examine union\\u000a formation among unmarried parents who have just had a child together. We used multinomial logistic regression to estimate\\u000a the effects of economic, cultural\\/interpersonal, and other factors on whether (relative to having no romantic relationship)\\u000a parents are romantically involved and living apart,

Marcia Carlson; Sara Mclanahan; Paula England

2004-01-01

447

The Formation of Stellar Clusters  

Microsoft Academic Search

We review recent work that investigates the formation of stellar clusters,\\u000aranging in scale from globular clusters through open clusters to the small\\u000ascale aggregates of stars observed in T associations. In all cases, recent\\u000aadvances in understanding have been achieved through the use of state of the\\u000aart stellar dynamical and gas dynamical calculations, combined with the\\u000apossibility of

Cathie J. Clarke; Ian A. Bonnell; Lynne A. Hillenbrand

1999-01-01

448

A New Spoke Formation Model  

Microsoft Academic Search

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

Geraint H. Jones; N. Krupp; H. Krueger; E. Roussos; W. Ip; D. G. Mitchell; S. M. Krimigis; J. Woch; A. Lagg; M. Fraenz; M. K. Dougherty; C. S. Arridge; H. J. McAndrews

2006-01-01

449

Pyrazines: occurrence, formation and biodegradation  

Microsoft Academic Search

Pyrazines are a class of compounds that occur almost ubiquitously in nature. Pyrazines can be synthesised chemically or biologically,\\u000a and are used as flavouring additives. The major formation of pyrazines occurs during heating of food. There is very little\\u000a information available on the degradation of these compounds. In humans and animals, pyrazines are excreted as glucuronates\\u000a or bound to glutathione

Rudolf Müller; Sugima Rappert

2010-01-01

450

Darwinian 'blind' hypothesis formation revisited  

Microsoft Academic Search

Over the last four decades arguments for and against the claim that creative hypothesis formation is based on Darwinian ‘blind’\\u000a variation have been put forward. This paper offers a new and systematic route through this long-lasting debate. It distinguishes\\u000a between undirected, random, and unjustified variation, to prevent widespread confusions regarding the meaning of undirected\\u000a variation. These misunderstandings concern Lamarckism, equiprobability,

Maria E. Kronfeldner

2010-01-01

451

Formation processes of framboidal pyrite  

NASA Astrophysics Data System (ADS)

Pyrite framboid formation may be the result of four consecutive processes: (1) nucleation and growth of initial iron monosulfide microcrystals; (2) reaction of the microcrystals to greigite (Fe 3S 4; (3) aggregation of uniformly sized greigite microcrystals, i.e., framboid growth; and (4) replacement of greigite framboids by pyrite. The uniform morphology, uniform size range, and ordering of the microcrystals in individual framboids, as well as the range of observed framboid structures from irregular aggregates to densely packed spherical aggregates and polyframboids, are consequences of these processes. Using DLVO theory (Derjaguin, Landau, Verwey, and Overbeek), we have evaluated the stability of colloidal, iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters. In addition to van der Waals attractive and double-layer repulsive forces, a term is included to account for the ferrimagnetic properties of greigite. Numerical models predict that magnetically saturated greigite particles >0.1 ?m in diameter will rapidly aggregate in either marine or fresh water. The aggregation model is in agreement with the sequence of greigite formation followed by pyrite framboid formation established in a previous experimental study (Sweeney and Kaplan, 1973) and is consistent with the occurrence of framboids composed of other magnetic minerals, e.g., greigite, magnetite, and magnesioferrite. Based on the temperature-dependent magnetic properties of greigite and aging experiments in hydrothermal solutions, this mechanism for framboid formation via precursor greigite could operate to temperatures of ˜200°C, consistent with the occasional occurrence of pyrite framboids in the paragenesis of metalliferous ore deposits.

Wilkin, R. T.; Barnes, H. L.

1997-01-01

452

Fracturing of subsurface earth formations  

Microsoft Academic Search

This is a hydraulic fracturing operation using a pelletized propping agent which has sustained load-carrying and deformation-resisting characteristics. The formation is first fractured and pellets are then introduced into the fracture to prop it open. The pellets are formed from a butadiene-containing rubber which has been cured and then hardened. The hardening is accomplished by cyclization of the rubber by

G. G. East; J. A. Burkhardt

1965-01-01

453

SCALE FORMATION IN CHRYSOPHYCEAN ALGAE  

PubMed Central

The cell wall of the marine chrysophycean alga Pleurochrysis scherfellii is composed of distinct wall fragments embedded in a gelatinous mass. The latter is a polysaccharide of pectic character which is rich in galactose and ribose. These wall fragments are identified as scales. They have been isolated and purified from the vegetative mother cell walls after zoospore formation. Their ultrastructure is described in an electron microscope study combining sectioning, freeze-etch, and negative staining techniques. The scales consist of a layer of concentrically arranged microfibrils (ribbons with cross-sections of 12 to 25 x 25 to 40 A) and underlying radial fibrils of similar dimensions. Such a network-plate is densely coated with particles which are assumed to be identical to the pectic component. The microfibrils are resistant to strong alkaline treatment and have been identified as cellulose by different methods, including sugar analysis after total hydrolysis, proton resonance spectroscopical examination (NMR spectroscopy) of the benzoylated product, and diverse histochemical tests. The formation and secretion of the scales can be followed along the maturing Golgi cisternae starting from a pronounced dilated "polymerization center" as a completely intracisternal process which ends in the exocytotic extrusion of the scales. The scales reveal the very same ultrastructure within the Golgi cisternae as they do in the cell wall. The present finding represents the first evidence on cellulose formation by the Golgi apparatus and is discussed in relation to a basic scheme for cellulose synthesis in plant cells in general.

Brown, R. Malcolm; Franke, Werner W.; Kleinig, Hans; Falk, Heinz; Sitte, Peter

1970-01-01

454

Clumpy disc and bulge formation  

NASA Astrophysics Data System (ADS)

We present a set of hydrodynamical/N-body controlled simulations of isolated gas-rich galaxies that self-consistently include supernova (SN) feedback and a detailed chemical evolution model, both tested in cosmological simulations. The initial conditions are motivated by the observed star-forming galaxies at z ˜ 2-3. We find that the presence of a multiphase interstellar media in our models promotes the growth of disc instability favouring the formation of clumps which, in general, are not easily disrupted on time-scales compared to the migration time. We show that stellar clumps migrate towards the central region and contribute to form a classical-like bulge with a Sérsic index, n > 2. Our physically motivated SN feedback has a mild influence on clump survival and evolution, partially limiting the mass growth of clumps as the energy released per SN event is increased, with the consequent flattening of the bulge profile. This regulation does not prevent the building of a classical-like bulge even for the most energetic feedback tested. Our SN feedback model is able to establish self-regulated star formation, producing mass-loaded outflows and stellar age spreads comparable to observations. We find that the bulge formation by clumps may coexist with other channels of bulge assembly such as bars and mergers. Our results suggest that galactic bulges could be interpreted as composite systems with structural components and stellar populations storing archaeological information of the dynamical history of their galaxy.

Perez, Josefa; Valenzuela, Octavio; Tissera, Patricia B.; Michel-Dansac, Leo

2013-09-01

455

Clumpy disc and bulge formation  

NASA Astrophysics Data System (ADS)

We present a set of hydrodynamical/N-body controlled simulations of isolated gas-rich galaxies that self-consistently include supernova (SN) feedback and a detailed chemical evolution model, both tested in cosmological simulations. The initial conditions are motivated by the observed star-forming galaxies at z ˜ 2-3. We find that the presence of a multiphase interstellar media in our models promotes the growth of disc instability favouring the formation of clumps which, in general, are not easily disrupted on time-scales compared to the migration time. We show that stellar clumps migrate towards the central region and contribute to form a classical-like bulge with a Sérsic index, n > 2. Our physically motivated SN feedback has a mild influence on clump survival and evolution, partially limiting the mass growth of clumps as the energy released per SN event is increased, with the consequent flattening of the bulge profile. This regulation does not prevent the building of a classical-like bulge even for the most energetic feedback tested. Our SN feedback model is able to establish self-regulated star formation, producing mass-loaded outflows and stellar age spreads comparable to observations. We find that the bulge formation by clumps may coexist with other channels of bulge assembly such as bars and mergers. Our results suggest that galactic bulges could be interpreted as composite systems with structural components and stellar populations storing archaeological information of the dynamical history of their galaxy.

Perez, Josefa; Valenzuela, Octavio; Tissera, Patricia B.; Michel-Dansac, Leo

2013-11-01

456

Modulators of urinary stone formation.  

PubMed

Urine contains compounds that modulate the nucleation, growth and aggregation of crystals as well as their attachment to renal epithelial cells. These compounds may function to protect the kidneys against: 1, the possibility of crystallization in tubular fluid and urine, which are generally metastable with respect to calcium salts, 2, crystal retention within the kidneys thereby preventing stone formation and 3, possibly against plaque formation at the nephron basement membrane. Since oxalate is the most common stone type, the effect of various modulators on calcium oxalate (CaOx) crystallization has been examined in greater details. Most of the inhibitory activity resides in macromolecules such as glycoproteins and glycosaminoglycans while nucleation promotion activity is most likely sustained by membrane lipids. Nephrocalcin, Tamm-Horsfall protein, osteopontin, urinary prothrombin fragment 1, and bikunin are the most studied inhibitory proteins while chondroitin sulfate (CS), heparan sulfate (HS) and hyaluronic acid (HA) are the best studied glycosaminoglycans. Crystallization modulating macromolecules discussed here are also prominent in cell injury, inflammation and recovery. Renal epithelial cells on exposure to oxalate and CaOx crystals produce some of the inflammatory molecules such as monocyte chemoattractant protein-1 (MCP-1) with no apparent role in crystal formation. In addition, macrophages surround the CaOx crystals present in the renal interstitium. These observations indicate a close relationship between inflammation and nephrolithiasis. PMID:14977559

Khan, Saeed R; Kok, Dirk J

2004-05-01

457

New insight in eggshell formation.  

PubMed

The matrix proteins that participate in crystalization fulfill important functions during the formation of the calcified tissues and contribute to the biomechanical properties of the mature product. We suggest that osteopontin (OPN) is part of an array of macromolecules synthesized and secreted by the cells adjacent to the mineralization front that self-assemble outside the cell and direct crystal formation. The OPN meets the theoretical requirements for involvement in the mineralization process. The phosphorylated residues of acidic phosphoprotein have been shown to exist in the protein as reactive monoesters that are available for interaction with other ions, among them crystal constituents such as calcium ions. In addition, sulfation of OPN was also found to be associated with mineralization of other tissues. In contrast to the calbindin gene, whose expression is dependent on the calcium flux, the regulation of OPN synthesis is at least in part dependent on the mechanical strain imposed by the resident egg. These results demonstrate the complexity of the regulation of the matrix genes governing eggshell formation. PMID:10901204

Lavelin, I; Meiri, N; Pines, M

2000-07-01

458

A New Spoke Formation Model  

NASA Astrophysics Data System (ADS)

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 für Bildung und Forschung, and by the Max Planck Gesellschaft.

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

459

Illusory contour formation survives crowding.  

PubMed

Flanked objects are difficult to identify using peripheral vision due to visual crowding, which limits conscious access to target identity. Nonetheless, certain types of visual information have been shown to survive crowding. Such resilience to crowding provides valuable information about the underlying neural mechanism of crowding. Here we ask whether illusory contour formation survives crowding of the inducers. We manipulated the presence of illusory contours through the (mis)alignment of the four inducers of a Kanizsa square. In the inducer-aligned condition, the observers judged the perceived shape (thin vs. fat) of the illusory Kanizsa square, manipulated by small rotations of the inducers. In the inducer-misaligned condition, three of the four inducers (all except the upper-left) were rotated 90°. The observers judged the orientation of the upper-left inducer. Crowding of the inducers worsened observers' performance significantly only in the inducer-misaligned condition. Our findings suggest that information for illusory contour formation survives crowding of the inducers. Crowding happens at a stage where the low-level featural information is integrated for inducer orientation discrimination, but not at a stage where the same information is used for illusory contour formation. PMID:22693333

Lau, Jonathan Siu Fung; Cheung, Sing-Hang

2012-06-12

460

Rock Cycle: Environments of Formation  

NSDL National Science Digital Library

This Science Object is the second of four Science Objects in the Rocks SciPack. It provides an in-depth exploration of the conditions and environment required during the formation of igneous, sedimentary, and metamorphic rocks. Igneous rock forms from the cooling and crystallization of magma. Sometimes the magma reaches Earth's surface and cools quickly; sometimes it does not reach the surface and thus cools slowly. Rocks at Earth's surface are subjected to processes of weathering and erosion, producing sediments as they are broken down. Sedimentary rock is formed when sediments are buried and solidified through various processes. Sedimentary rock buried deep enough may be transformed into metamorphic rock or melted down to magma. Rock formed deep within the crust (either igneous or metamorphic) may be forced up again to become land surface and even mountains by the forces that drive the motion of Earth's plates. Subsequently, this new rock too will erode. Learning Outcomes:� Realize that different rocks have specific origins, and that they are the product of any number of processes.� Identify the processes through which igneous, sedimentary, and metamorphic rock form.� Explain the role of intermediary materials such as sediment and magma in the formation of different kinds of rock.� Provide an overarching description of the steps in the rock cycle, the formation of sedimentary rock, the re-forming of rock by heat and pressure, and the process by which re-formed rock can return to the surface.

National Science Teachers Association (NSTA)

2006-11-01