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1

Thermal Gradient Holes At Coso Geothermal Area (1976) | Open Energy  

Open Energy Info (EERE)

Thermal Gradient Holes At Coso Geothermal Area (1976) Thermal Gradient Holes At Coso Geothermal Area (1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Coso Geothermal Area (1976) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1976 Usefulness useful DOE-funding Unknown Notes Temperatures have been obtained to depths up to 133 m in 22 boreholes with measurements being made at least four times in each borehole. Geothermal gradients ranged from 240C/km to 450 0C/km. References Combs, J. (1 December 1976) Heat flow determinations and implied thermal regime of the Coso geothermal area, California Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Coso_Geothermal_Area_(1976)&oldid=511217"

2

Category:Thermal Gradient Holes | Open Energy Information  

Open Energy Info (EERE)

in category "Thermal Gradient Holes" This category contains only the following page. T Thermal Gradient Holes Retrieved from "http:en.openei.orgwindex.php?titleCategory:T...

3

Thermal Gradient Holes | Open Energy Information  

Open Energy Info (EERE)

Thermal Gradient Holes Thermal Gradient Holes Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Thermal Gradient Holes Details Activities (50) Areas (39) Regions (4) NEPA(29) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Exploration Drilling Parent Exploration Technique: Exploration Drilling Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Field wide fluid flow characteristics if an array of wells are drilled Thermal: Mapping and projecting thermal anomalies Cost Information Low-End Estimate (USD): 5.00500 centUSD 0.005 kUSD 5.0e-6 MUSD 5.0e-9 TUSD / foot Median Estimate (USD): 16.501,650 centUSD 0.0165 kUSD 1.65e-5 MUSD 1.65e-8 TUSD / foot High-End Estimate (USD): 50.005,000 centUSD

4

Temperature, heat flow maps and temperature gradient holes |...  

Open Energy Info (EERE)

Temperature, heat flow maps and temperature gradient holes Author T. G. Zacharakis Organization Colorado Geological Survey in Cooperation with the U.S. Department of Energy...

5

Thermal Gradient Holes At Long Valley Caldera Geothermal Area...  

Open Energy Info (EERE)

Date 1978 - 1985 Usefulness useful DOE-funding Unknown Exploration Basis Thermal gradient drilling also continued during this period, consisting of several holes including: The...

6

Thermal Gradient Holes At Chena Geothermal Area (EERE, 2010)...  

Open Energy Info (EERE)

EERE, 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Chena Geothermal Area (EERE, 2010) Exploration Activity...

7

Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski,...  

Open Energy Info (EERE)

Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski, Et Al.,...

8

Thermal Gradient Holes At Chena Geothermal Area (Erkan, Et Al...  

Open Energy Info (EERE)

Erkan, Et Al., 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Chena Geothermal Area (Erkan, Et Al., 2007)...

9

Thermal Gradient Holes At Obsidian Cliff Area (Hulen, Et Al....  

Open Energy Info (EERE)

Obsidian Cliff Area (Hulen, Et Al., 2003) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Obsidian Cliff Area (Hulen,...

10

Thermal Gradient Holes At Glass Mountain Area (Cumming And Mackie...  

Open Energy Info (EERE)

Area (Cumming And Mackie, 2007) Exploration Activity Details Location Glass Mountain Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not...

11

Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009)  

Open Energy Info (EERE)

Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Exploration Activity Details Location Salt Wells Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 2008 - 2008 Usefulness not indicated DOE-funding Unknown Exploration Basis Vulcan increased exploration efforts in the summer and fall of 2008, during which time the company drilled two temperature gradient holes (86-15 O on Pad 1 and 17-16 O on Pad 3); conducted seismic, gravity and magnetotelluric surveys; and drilled deep exploration wells at Pads 6 and 8 and binary wells at Pads 1, 2, 4, and 7. Notes

12

Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett,  

Open Energy Info (EERE)

Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, 2004) Exploration Activity Details Location Central Nevada Seismic Zone Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

13

Thermal Gradient Holes At Coso Geothermal Area (1974) | Open Energy  

Open Energy Info (EERE)

Coso Geothermal Area (1974) Coso Geothermal Area (1974) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1974 Usefulness useful DOE-funding Unknown Exploration Basis Use heat flow studies for the first time at Coso to indicate the presence or absence of abnormal heat Notes Located 10 sites for heat flow boreholes using available seismic ground noise and electrical resistivity data; data collected from 9 of 10; thermal conductivity measurements were completed using both the needle probe technique and the divided bar apparatus with a cell arrangement. In the upper few hundred meters of the subsurface heat is being transferred by a conductive heat transfer mechanism with a value of ~ 15 µcal/cm2sec; the background heat flow is ~ 3.5 HFU.

14

Formation of morphogen gradients: Local accumulation time  

Science Journals Connector (OSTI)

Spatial regulation of cell differentiation in embryos can be provided by morphogen gradients, which are defined as the concentration fields of molecules that control gene expression. For example, a cell can use its surface receptors to measure the local concentration of an extracellular ligand and convert this information into a corresponding change in its transcriptional state. We characterize the time needed to establish a steady-state gradient in problems with diffusion and degradation of locally produced chemical signals. A relaxation function is introduced to describe how the morphogen concentration profile approaches its steady state. This function is used to obtain a local accumulation time that provides a time scale that characterizes relaxation to steady state at an arbitrary position within the patterned field. To illustrate the approach we derive local accumulation times for a number of commonly used models of morphogen gradient formation.

Alexander M. Berezhkovskii; Christine Sample; Stanislav Y. Shvartsman

2011-05-06T23:59:59.000Z

15

Thermal Gradient Holes At Fort Bliss Area (DOE GTP) | Open Energy...  

Open Energy Info (EERE)

Fort Bliss Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fort Bliss Area (DOE GTP) Exploration...

16

Thermal Gradient Holes At Twenty-Nine Palms Area (Page, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Twenty-Nine Palms Thermal Gradient Holes At Twenty-Nine Palms Geothermal Area (Page, Et Al., 2010) Exploration Activity Details Location Twenty-Nine Palms Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes From November 2008 to March 2009, Seabees from the Naval Construction Division (NCD) successfully completed fivetemperature gradient holes for the GPO. Samples taken from each hole were similar in nature; mixtures of sand and conglomerates with the occasional granite sections were typically encountered. Each hole varied slightly in depth, ranging from 600ft to 1,000ft; however, each hole has been completed to acceptable standards of the GPO. Upon completion of drilling, 3" metal tubing was inserted to

17

Thermal Gradient Holes At Hualalai Northwest Rift Area (Thomas, 1986) |  

Open Energy Info (EERE)

Hualalai Northwest Rift Hualalai Northwest Rift Area (Thomas, 1986) Exploration Activity Details Location Hualalai Northwest Rift Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes Although not part of the current effort, two deep (approximately 2000 m) exploratory wells were drilled on the north flank of Hualalai near Puu Waawaa cinder cone. The geophysical data used for siting these wells were proprietary and hence unavailable for publication; however, the temperatures measured at the bottoms of the wells were reported to be below 20degrees C. Chemical analysis of water samples taken from these wells did not provide useful geothermal data due to contamination of the well water with drilling muds References Donald M. Thomas (1 January 1986) Geothermal Resources Assessment In

18

Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Exploration Activity Details Location Hot Springs Ranch Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley

19

Thermal Gradient Holes At Lightning Dock Area (Cunniff & Bowers, 2005) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Lightning Dock Area Thermal Gradient Holes At Lightning Dock Area (Cunniff & Bowers, 2005) Exploration Activity Details Location Lightning Dock Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The two gradient holes were sited on federal geothermal leases owned by Lightning Dock Geothermal, Inc. and both were drilled into lakebed sediments some distance from the intense shallow geothermal anomaly located in the eastern half of Section 7, Township 25 South, Range 19 West. References Roy A. Cunniff, Roger L. Bowers (2005) Final Technical Report, Geothermal Resource Evaluation And Definitioni (Gred) Program-Phases I, Ii, And Iii For The Animas Valley, Nm Geothermal Resource Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Lightning_Dock_Area_(Cunniff_%26_Bowers,_2005)&oldid=387460"

20

Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Exploration Activity Details Location Kilauea Summit Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes A deep borehole was drilled at the summit of Kilauea volcano, Hawaii, between April 6 and July 9, 1973. The hole is located approximately 1 km south of the edge of Halemaumau crater (Figs. 1 and 2), a crater within the summit caldera of the volcano. The total depth of the hole is 1262 m (4141 ft) measured from the derrick floor at an altitude of 1102 m (3616 ft). A description of the drilling program and some of the results obtained have

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Exploration Activity Details Location Socorro Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes Pre-existing evidence includes heat gradients of upwards of 490mW/m2 from thermal-gradient wells, tepid spring waters (32oC) and silica geochemistry indicating thermal waters with a minimum of 82 degrees C at depth References Lara Owens, Richard Baars, David Norman, Harold Tobin (2005) New Methods In Exploration At The Socorro Peak Kgra- A Gred Iii Project Retrieved from

22

Time (hole?) machines John Byron Manchak  

E-Print Network [OSTI]

Time (hole?) machines John Byron Manchak Department of Philosophy, University of Washington, Box machines Hole machines Time travel General relativity a b s t r a c t Within the context of general relativity, we consider a type of "time machine" and introduce the related "hole machine". We review what

Manchak, John

23

Thermal Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) |  

Open Energy Info (EERE)

Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Exploration Activity Details Location Northern Basin and Range Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

24

Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Twenty-Nine Palms Geothermal Area (Sabin, Et Al., 2010) Exploration Activity Details Location Twenty-Nine Palms Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes The first and only Seabee drilling project was the installation of five TGHs at the Camp Wilson region of the MCAGCC Marine base near Twenty-Nine Palms, CA. While the program was a success and GPO identified an anomaly where a deep, slim hole is to be drilled in June, 2010, the Seabee rig was sent oversees soon after drilling was completed. If/when another rig

25

Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Exploration Activity Details Location Northwest Basin and Range Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

26

Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell,  

Open Energy Info (EERE)

Hot Creek Ranch Area (Benoit & Blackwell, Hot Creek Ranch Area (Benoit & Blackwell, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Exploration Activity Details Location Upper Hot Creek Ranch Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes Ten temperature gradient holes up to 500' deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400' encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The

27

Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann, 2004) |  

Open Energy Info (EERE)

Blue Mountain Area (Fairbank & Neggemann, 2004) Blue Mountain Area (Fairbank & Neggemann, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann, 2004) Exploration Activity Details Location Blue Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown References Brian D. Fairbank, Kim V. Niggemann (2004) Deep Blue No 1- A Slimhole Geothermal Discovery At Blue Mountain, Humboldt County, Nevada Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Blue_Mountain_Area_(Fairbank_%26_Neggemann,_2004)&oldid=386709" Category: Exploration Activities What links here Related changes Special pages Printable version Permanent link

28

Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) | Open  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) Exploration Activity Details Location Hawthorne Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes The Navy recently completed a temperature gradient hole (TGH) drilling campaign. Results suggest multiple resources may exist on HAD lands. To further define the shallow resource, the Navy will drill one or two

29

Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Exploration Activity Details Location Kilauea East Rift Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Two separate phases of geothermal exploratory drilling have occurred on the lower East Rift. The first was essentially a wildcat venture with relatively little surface exploratory data having been gathered, whereas the second was initiated after somewhat more geoscience information had been acquired under the Hawaii Geothermal Project. The results of the successful exploratory drilling program on the Kilauea

30

Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) | Open Energy  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) Exploration Activity Details Location Crump's Hot Springs Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes 8 wells References (1 January 2011) GTP ARRA Spreadsheet Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Crump%27s_Hot_Springs_Area_(DOE_GTP)&oldid=402699"

31

Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) | Open Energy  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) Exploration Activity Details Location Fish Lake Valley Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes 2 wells References (1 January 2011) GTP ARRA Spreadsheet Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Fish_Lake_Valley_Area_(DOE_GTP)&oldid=511222" Categories:

32

Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al., 2010) |  

Open Energy Info (EERE)

Chocolate Mountains Area (Alm, Et Al., 2010) Chocolate Mountains Area (Alm, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al., 2010) Exploration Activity Details Location Chocolate Mountains Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes "Shallow temperature gradient drilling began at the CMAGR in January of 2010. 13 temperature gradient holes were completed to a depth of 500' below ground surface. Sites were selected based on the compilation of previous exploration and resulting data is being integrated into the most recent geologic model. This model will form the basis for the selection of a deeper (2000'-4000') temperature gradient drilling campaign at the CMAGR in

33

Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen...  

Open Energy Info (EERE)

(1993) Heat Flow From Four New Research Drill Holes In The Western Cascades, Oregon, Usa Additional References Retrieved from "http:en.openei.orgwindex.php?titleThermalGr...

34

Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Lightning Dock Area Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) Exploration Activity Details Location Lightning Dock Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The awardee conducted seismic, gravity, resistivity, and airborne magnetic surveys, drilled temperature-gradient wells, and selected a location for a test well (52-7). The test well was drilled to a total depth of 770 m during 2003. Maximum temperatures approached 140degrees C and a short flow test suggested that a production well could be drilled to 600 m and produce economic volumes of 130-140degrees C fluid. A final assessment of the resource is currently being performed. References N. R. Warpinski, A. R. Sattler, R. Fortuna, D. A. Sanchez, J.

35

Thermal Gradient Holes At Chocolate Mountains Area (Sabin, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Chocolate Mountains Area Thermal Gradient Holes At Chocolate Mountains Area (Sabin, Et Al., 2010) Exploration Activity Details Location Chocolate Mountains Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes In lieu of Seabee TGH drilling, GPO awarded a large IDIQ TGH drilling contract in December, 2009. Over the next two years, 90 500-ft TGHs will be installed at select sites in California and Nevada. Interim data from this campaign are already available for the Chocolate Mountains and Hawthorne. Results of these programs can be found in the Chocolate Mountains and Hawthorne papers also available in this volume. References Andrew Sabin, S. Bjornstad, M. Lazaro, D. Meade, C. Page, S. Alm, A. Tiedeman, W. C. Huang (2010) Navy's Geothermal Program Office: Overview

36

Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al.,  

Open Energy Info (EERE)

2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al., 2004) Exploration Activity Details Location Lake City Hot Springs Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The Lake City site, which is located in far northeastern California, consists of a previously identified geothermal site that has been explored with both geophysics and drilling (Hedel, 1981), but has not been characterized adequately to allow accurate siting or drilling of production wells. Some deep wells, several seismic lines, limited gravity surveys, and geochemical and geological studies have suggested that the geothermal

37

Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett,  

Open Energy Info (EERE)

Walker-Lane Transitional Zone Region (Pritchett, Walker-Lane Transitional Zone Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett, 2004) Exploration Activity Details Location Walker-Lane Transition Zone Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

38

Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al.,  

Open Energy Info (EERE)

Hot Springs Area (Shevenell, Et Al., Hot Springs Area (Shevenell, Et Al., 2008) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al., 2008) Exploration Activity Details Location Spencer Hot Springs Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Collaboration with the gold mining industry has brought two new geothermal discoveries to the attention of the geothermal community. Exploration holes at Tungsten Mountain and McGuiness Hills (Spencer Hot Springs?) in 2004 and 2005 encountered hot water and steam at depths of meters with fluid geothermometry indicating reservoir temperatures of 170 to 200oC. More information can be obtained from the Nevada Bureau of Mines and Geology web

39

Thermal Gradient Holes At Tungsten Mountain Area (Kratt, Et Al., 2008) |  

Open Energy Info (EERE)

Kratt, Et Al., 2008) Kratt, Et Al., 2008) Exploration Activity Details Location Tungsten Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes twenty-three gold exploration holes were drilled by Newcrest Resources, Inc. during 2005 and 2006 along the range front. These holes approached or exceeded 300 m in depth and all holes encountered hot water and/or steam. Despite the high temperatures encountered at relatively shallow depths, there are no active geothermal features such as hot springs or steam vents at the surface. The presence of small outcrops of argillic alteration containing anomalous gold attracted the interest of exploration geologists. References Christopher Kratt, Mark Coolbaugh, Chris Sladek, Rick Zehner, Robin

40

Thermal Gradient Holes At Hawthorne Area (Sabin, Et Al., 2010) | Open  

Open Energy Info (EERE)

Sabin, Et Al., 2010) Sabin, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hawthorne Area (Sabin, Et Al., 2010) Exploration Activity Details Location Hawthorne Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes In lieu of Seabee TGH drilling, GPO awarded a large IDIQ TGH drilling contract in December, 2009. Over the next two years, 90 500-ft TGHs will be installed at select sites in California and Nevada. Interim data from this campaign are already available for the Chocolate Mountains and Hawthorne. Results of these programs can be found in the Chocolate Mountains and Hawthorne papers also available in this volume. References Andrew Sabin, S. Bjornstad, M. Lazaro, D. Meade, C. Page, S. Alm, A.

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2002) | Open  

Open Energy Info (EERE)

Et Al., 2002) Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2002) Exploration Activity Details Location Cove Fort Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The project at Cove Fort/Sulphurdale in Utah, T26S R6/7W, is concerned with locating and drilling a 900-meter well to explore the western extension of the Cove Fort-Sulphurdale geothermal area. The geophysical exploration consisted of resistivity, ground magnetic, and microgravity surveys that were made to site the well in an optimum location. Drilling of the test well was completed in the fall of 2001 and results are currently being evaluated. The total depth of the well is 598 m with a

42

Thermal Gradient Holes At Fort Bidwell Area (Lafleur, Et Al., 2010) | Open  

Open Energy Info (EERE)

Bidwell Area (Lafleur, Et Al., 2010) Bidwell Area (Lafleur, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fort Bidwell Area (Lafleur, Et Al., 2010) Exploration Activity Details Location Fort Bidwell Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes "Four wells have been successfully drilled into this resource since the early 1980s using a combination of funds provided by the California Energy Commission (CEC) and the United State Department of Energy (USDOE). The first three wells, FB-1, -2 and -3 have been discussed in a previous paper (Barker et al., 2005). The current status of the FBIC project to evaluate the potential geothermal resource under the reservation is that a deep

43

Thermal Gradient Holes At Chena Area (Erkan, Et. Al., 2008) | Open Energy  

Open Energy Info (EERE)

Chena Area (Erkan, Et. Al., Chena Area (Erkan, Et. Al., 2008) Exploration Activity Details Location Chena Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes MULTI-STAGE DRILLING Once a hole is drilled the natural-state pressure distribution with depth is essentially unrecoverable (Grant et al., 1982). One of the best ways to mitigate this effect is to use multi-stage drilling (White et al., 1975; Grant et al., 1982). This type of drilling was applied at Chena and its usefulness in understanding the natural flow regimes is demonstrated. Here, we illustrate how high-quality equilibrium temperature logs can often be used to identify permeable fractures. The independent interpretations of flow regimes based on temperature-depth curves and the

44

Thermal Gradient Holes At Tungsten Mountain Area (Shevenell, Et Al., 2008)  

Open Energy Info (EERE)

Shevenell, Et Al., 2008) Shevenell, Et Al., 2008) Exploration Activity Details Location Tungsten Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Collaboration with the gold mining industry has brought two new geothermal discoveries to the attention of the geothermal community. Exploration holes at Tungsten Mountain and McGuiness Hills (Figure 1) in 2004 and 2005 encountered hot water and steam at depths of meters with fluid geothermometry indicating reservoir temperatures of 170 to 200oC. More information can be obtained from the Nevada Bureau of Mines and Geology web site (www.nbmg.unr.edu/geothermal/gtmap.pdf), and from a PowerPoint presentation titled 'Geothermal Exploration Short Stories' posted on the Geothermal Resources Council web site

45

Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski, Et Al., 2002)  

Open Energy Info (EERE)

2) 2) Exploration Activity Details Location Cove Fort Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The project at Cove Fort/Sulphurdale in Utah, T26S R6/7W, is concerned with locating and drilling a 900-meter well to explore the western extension of the Cove Fort-Sulphurdale geothermal area. The geophysical exploration consisted of resistivity, ground magnetic, and microgravity surveys that were made to site the well in an optimum location. Drilling of the test well was completed in the fall of 2001 and results are currently being evaluated. The total depth of the well is 598 m with a non-equilibrated maximum temperature probably in the range of 157degrees C and a very complicated geologic structure.

46

Hot Pot Contoured Temperature Gradient Map  

SciTech Connect (OSTI)

Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.

Lane, Michael

2013-06-28T23:59:59.000Z

47

Hot Pot Contoured Temperature Gradient Map  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.

Lane, Michael

48

Top hole drilling with dual gradient technology to control shallow hazards  

E-Print Network [OSTI]

3.2 Riserless Dual Gradient Drilling Technology Description .........................36 3.2.1 Kick Detection.............................................................................37 3.2.2 Well Control ?Modified Driller?s Method... ? PRESSURE @ TOP OF KICK GRAPHS ? SET #1..........................140 ix Page APPENDIX F ? PRESSURE @ TOP OF KICK GRAPHS ? SET #2 ..........................159 VITA...

Elieff, Brandee Anastacia Marie

2006-10-30T23:59:59.000Z

49

Distinguishing causal time from Minkowski time and a model for the black hole quantum eigenstates  

E-Print Network [OSTI]

A discussion is presented of the principle of black hole com- plementarity. It is argued that this principle could be viewed as a breakdown of general relativity, or alternatively, as the introduction of a time variable with multiple `sheets' or `branches' A consequence of the theory is that the stress-energy tensor as viewed by an outside observer is not simply the Lorentz-transform of the tensor viewed by an ingoing observer. This can serve as a justification of a new model for the black hole atmosphere, recently re-introduced. It is discussed how such a model may lead to a dynamical description of the black hole quantum states.

G. 't Hooft

1997-11-18T23:59:59.000Z

50

Faster Time Response by the Use of Wire Electrodes in Capacitive Salinity Gradient Energy Systems  

Science Journals Connector (OSTI)

Comparing salinity gradient power to other ocean power sources, such as wind, ocean currents, wave, tidal streams, and thermal gradients, it is supreme partly in that it has the second largest power potential, but foremost because it is focused at river deltas (rather than being distributed over the ocean areas across the world). ... We also studied the asymmetric behavior of response time in concentrated saline solution and dilute saline solution that is reported for our branch of technologies. ... solns. of different salinities. ...

Odne S. Burheim; Fei Liu; Bruno B. Sales; Olivier Schaetzle; Cees J. N. Buisman; Hubertus V. M. Hamelers

2012-08-28T23:59:59.000Z

51

Measurement of time dependent fields in high gradient superconducting quadrupoles for the Tevatron  

SciTech Connect (OSTI)

Magnetic field measurements have been performed on prototype and production magnets from two high gradient superconducting quadrupoles designs. One design is a double shell quadrupole with 36 strand Rutherford cable. The other design is a single shell quadrupole with 5 individually monolithic strands connected in series. These magnets have similar bore diameters and cable dimensions. However, there are significant differences between the two designs, as well as differences between prototype and production magnets within each design, with regard to Cu to superconductor ratio, filament diameter and filament spacing to strand diameter. The time dependence of fixed currents of the measured magnetic fields is discussed. 9 refs., 6 figs., 1 tab.

Lamm, M.J.; Coulter, K.; Gourlay, S.; Jaffery, T.S.

1990-10-01T23:59:59.000Z

52

No black holes, but extra time at LHC  

Science Journals Connector (OSTI)

... , microscopic black holes have so far failed to appear inside the Large Hadron Collider (LHC), scientists there have revealed. The result, which will be posted this week on ... be posted this week on arXiv.org, comes as researchers make plans to keep the LHC running until the end of 2012, rather than 2011 as previously scheduled. The 27 ...

Geoff Brumfiel

2010-12-14T23:59:59.000Z

53

USING CENTER HOLE HEAT TRANSFER TO REDUCE FORMATION TIMES FOR CERAMIC WASTE FORMS FROM PYROPROCESSING  

SciTech Connect (OSTI)

The waste produced from processing spent fuel from the EBR II reactor must be processed into a waste form suitable for long term storage in Yucca Mountain. The method chosen produces zeolite granules mixed with glass frit, which must then be converted into a solid. This is accomplished by loading it into a can and heating to 900 C in a furnace regulated at 915 C. During heatup to 900 C, the zeolite and glass frit react and consolidate to produce a sodalite monolith. The resultant ceramic waste form (CWF) is then cooled. The waste is 52 cm in diameter and initially 300 cm long but consolidates to 150 cm long during the heating process. After cooling it is then inserted in a 5-DHLW/DOE SNF Long Canister. Without intervention, the waste takes 82 hours to heat up to 900 C in a furnace designed to geometrically fit the cylindrical waste form. This paper investigates the reduction in heating times possible with four different methods of additional heating through a center hole. The hole size is kept small to maximize the amount of CWF that is processed in a single run. A hole radius of 1.82 cm was selected which removes only 1% of the CWF. A reference computation was done with a specified inner hole surface temperature of 915 C to provide a benchmark for the amount of improvement which can be made. It showed that the heatup time can potentially be reduced to 43 hours with center hole heating. The first method, simply pouring high temperature liquid aluminum into the hole, did not produce any noticeable effect on reducing heat up times. The second method, flowing liquid aluminum through the hole, works well as long as the velocity is high enough (2.5 cm/sec) to prevent solidification of the aluminum during the initial front movement of the aluminum into the center hole. The velocity can be reduced to 1 cm/sec after the initial front has traversed the ceramic. This procedure reduces the formation time to near that of the reference case. The third method, flowing a gas through the center hole, also works well as long as the heat capacity times the velocity of the gas is equivalent to that of the flowing aluminum, and the velocity is high enough to produce an intermediate size heat transfer coefficient. The fourth method, using an electric heater, works well and heater sizes between 500 to 1000 Watts are adequate. These later three methods all can reduce the heatup time to 44 hours.

Kenneth J. Bateman; Charles W. Solbrig

2006-07-01T23:59:59.000Z

54

Kerr black holes and time profiles of gamma-ray bursts  

E-Print Network [OSTI]

The cumulative light curves of gamma-ray bursts (GRBs) smooth the spiky nature of the running light curve. The cumulative count increases in an approximately linear way with time t for most bursts. In 19 out of 398 GRBs with T90 > 2s, the cumulative light curve was found to increase with time as \\~t^2 implying a linear increase in the running light curve. The non-linear sections last for a substantial fraction of the GRB duration, have a large proportion of the cumulative count and many resolved pulses that usually end with the highest pulse in the burst. The reverse behaviour was found in 11 GRBs where the running light curve decreased with time and some bursts are good mirror images of the increases. These GRBs are among the spectrally hardest bursts observed by BATSE. The most likely interpretation is that these effects are signatures of black holes that are either being spun up or down in the accretion process. In the spin up case, the increasing Kerr parameter of the black hole allows additional rotational and accretion energy to become available for extraction. The process is reversed if the black hole is spun down by magnetic field torques. The luminosity changes in GRBs are consistent with the predictions of the BZ process and neutrino annihilation and thus provide the link to spinning black holes. GRBs provide a new window for studying the general relativistic effects of Kerr black holes.

S. McBreen; B. McBreen; L. Hanlon; F. Quilligan

2002-08-19T23:59:59.000Z

55

Rotating Black Holes in Gauged Supergravities; Thermodynamics, Supersymmetric Limits, Topological Solitons and Time Machines  

E-Print Network [OSTI]

We study the thermodynamics of the recently-discovered non-extremal charged rotating black holes of gauged supergravities in five, seven and four dimensions, obtaining energies, angular momenta and charges that are consistent with the first law of thermodynamics. We obtain their supersymmetric limits by using these expressions together with an analysis of the AdS superalgebras including R-charges. We give a general discussion of the global structure of such solutions, and apply it in the various cases. We obtain new regular supersymmetric black holes in seven and four dimensions, as well as reproducing known examples in five and four dimensions. We also obtain new supersymmetric non-singular topological solitons in five and seven dimensions. The rest of the supersymmetric solutions either have naked singularities or naked time machines. The latter can be rendered non-singular if the asymptotic time is periodic. This leads to a new type of quantum consistency condition, which we call a Josephson quantisation condition. Finally, we discuss some aspects of rotating black holes in Godel universe backgrounds.

M. Cvetic; G. W. Gibbons; H. Lu; C. N. Pope

2005-11-09T23:59:59.000Z

56

An execution time and energy model for an energy-aware execution of a conjugate gradient method with CPU/GPU collaboration  

Science Journals Connector (OSTI)

The parallel preconditioned conjugate gradient method (CGM) is used in many applications of scientific computing and often has a critical impact on their performance and energy consumption. This article investigates the energy-aware execution of the ... Keywords: Conjugate gradient method, Energy awareness, Energy model, Execution time model, GPU, RAPL

Jens Lang, Gudula Rnger

2014-09-01T23:59:59.000Z

57

White holes and eternal black holes  

E-Print Network [OSTI]

We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi- thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal.

Stephen D. H. Hsu

2011-11-16T23:59:59.000Z

58

Optimizing artificial lift operations through the use of wireless conveyed real time bottom hole data  

SciTech Connect (OSTI)

The use of an innovative wireless bottom hole pressure/temperature telemetry acquisition system in artificial lift operations can dramatically improve efficiency and optimize fluid producing rates in those wells. The tool is installed into the producing well in the vicinity of the perforations, measuring and transmitting the producing bottom hole pressures and temperatures to the surface for instantaneous control of the surface pumping motor speed. This insures the lowest possible fluid level back pressures, thus allowing for the highest possible fluid entry into the wellbore from that reservoir`s capacity. Operating costs per barrel are lowered since the maximum oil production can now be realized from existing wells. The telemetry tool is deployed with standard slickline equipment and is installed inside a well in a manner similar to ordinary pressure recorder tools. Several unique advantages of the tool are: (1) no moving parts; (2) no wireline to the surface; (3) real time measurement of bottom hole data; and (4) slickline retrievable. Future versions of the acquisition system tool will improve operating efficiency in the following ways: (1) Temperature monitoring and control of perforation scaling, tubular waxing, and tubular hydrating plugs. (2) Provide data necessary to create diagnostically predictive IPR curves through monitoring of reservoir in-flow rates. (3) Enabling early warning of water encroachment or lensing through fluid resistivity monitoring.

Campbell, B.; MacKinnon, J.; Bandy, T.R.; Hampton, T.

1996-12-31T23:59:59.000Z

59

Fast Self-Healing Gradients  

E-Print Network [OSTI]

We present CRF-Gradient, a self-healing gradient algorithm that provably reconfigures in O(diameter) time. Self-healing gradients are a frequently used building block for distributed self-healing systems, but previous ...

Beal, Jacob

60

Real-time solar wind prediction based on SDO/AIA coronal hole data  

E-Print Network [OSTI]

We present an empirical model based on the visible area covered by coronal holes close to the central meridian in order to predict the solar wind speed at 1 AU with a lead time up to four days in advance with a 1hr time resolution. Linear prediction functions are used to relate coronal hole areas to solar wind speed. The function parameters are automatically adapted by using the information from the previous 3 Carrington Rotations. Thus the algorithm automatically reacts on the changes of the solar wind speed during different phases of the solar cycle. The adaptive algorithm has been applied to and tested on SDO/AIA-193A observations and ACE measurements during the years 2011-2013, covering 41 Carrington Rotations. The solar wind speed arrival time is delayed and needs on average 4.02 +/- 0.5 days to reach Earth. The algorithm produces good predictions for the 156 solar wind high speed streams peak amplitudes with correlation coefficients of cc~0.60. For 80% of the peaks, the predicted arrival matches within ...

Rotter, T; Temmer, M; Vrsnak, B

2015-01-01T23:59:59.000Z

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61

Ultrashort echo time (UTE) imaging using gradient pre-equalization and compressed sensing  

E-Print Network [OSTI]

in soil, shale rock, or polymeric materials. In a polymer network the T2* can range from the order of 10 ls to 1 ms depend- ing on the rigidity of the network [9]. The other systems present similarly short relaxation times. Thus, UTE will open new possibil... Press, New York, 2000. [10] C.R. Mller, J.F. Davidson, J.S. Dennis, P.S. Fennell, L.F. Gladden, A.N. Hayhurst, et al., Real-time measurement of bubbling phenomena in a three-dimensional gas-fluidized bed using ultrafast magnetic resonance imaging, Phys...

Fabich, Hilary T.; Benning, Martin; Sederman, Andrew J.; Holland, Daniel J.

2014-06-27T23:59:59.000Z

62

Photonic quantum memory in two-level ensembles based on modulating the refractive index in time: equivalence to gradient echo memory  

E-Print Network [OSTI]

We present a quantum memory protocol that allows to store light in ensembles of two-level atoms, e.g. rare-earth ions doped into a crystal, by modulating the refractive index of the host medium of the atoms linearly in time. We show that under certain conditions the resulting dynamics is equivalent to that underlying the gradient echo memory protocol, which relies on a spatial gradient of the atomic resonance frequencies. We discuss the prospects for an experimental implementation.

Clark, James; Simon, Christoph

2012-01-01T23:59:59.000Z

63

Ch. VII, Temperature, heat flow maps and temperature gradient...  

Open Energy Info (EERE)

Ch. VII, Temperature, heat flow maps and temperature gradient holes Author T. G. Zacharakis Editor T. G. Zacharakis Published Colorado Geological Survey in Cooperation with the...

64

Time-dependent models of two-phase accretion discs around black holes  

Science Journals Connector (OSTI)

......at low accretion rates the disc close to...dependently. black hole physics|galaxies: jets...of the soft photon rate S soft passes through the area...higher accretion rates close to the Eddington...as small and the physics as simple as possible......

M. Mayer; J. E. Pringle

2007-03-21T23:59:59.000Z

65

Black Hole Formation in Core-Collapse Supernovae and Time-of-Flight Measurements of the Neutrino Masses  

E-Print Network [OSTI]

Early black hole formation in core-collapse supernovae may be triggered by mass accretion or a change in the high-density equation of state. We consider the possibility that black hole formation happens when the flux of neutrinos is still measurably high. If this occurs, then the neutrino signal from the supernova will be terminated abruptly (the transition takes $\\lesssim 0.5$ ms). The properties and duration of the signal before the cutoff are important measures of both the physics and astrophysics of the cooling proto-neutron star. For the event rates expected in present and proposed detectors, the cutoff will generally appear sharp, thus allowing model-independent time-of-flight mass tests for the neutrinos after the cutoff. If black hole formation occurs relatively early, within a few ($\\sim 1$) seconds after core collapse, then the expected luminosities are of order $L_{BH} = 10^{52}$ erg/s per flavor. In this case, the neutrino mass sensitivity can be extraordinary. For a supernova at a distance $D = 10$ kpc, SuperKamiokande can detect a $\\bar{\

J. F. Beacom; R. N. Boyd; A. Mezzacappa

2000-10-19T23:59:59.000Z

66

Stabilization of Bottom Hole Temperature With Finite Circulation Time and Fluid Flow  

Science Journals Connector (OSTI)

......the finite drilling rate, (2...convection in the borehole. Luheshi...1000 times larger than the geothermal...50 hr after drilling. The only...section of the borehole is drilled...in errors as large as -21 per...function of the borehole depth, an...mud during drilling operations......

P. Y. Shen; A. E. Beck

1986-07-01T23:59:59.000Z

67

RHIC | Black Holes?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Black Holes at RHIC? Black Holes at RHIC? Further discussion by Physicist Dmitri Kharzeev on why RHIC cannot produce a real gravitational black hole Black holes are among the most mysterious objects in the universe. The gravitational field of a black hole is so strong that Einstein's general relativity tells us that nothing, not even light, can escape from the black hole's interior. However, in 1974 physicist Stephen Hawking demonstrated that black holes must emit radiation once the quantum effects are included. According to quantum mechanics, the physical vacuum is bubbling with short-lived virtual particle-antiparticle pairs. Creation of a particle-antiparticle pair from the vacuum conflicts with energy conservation, but energy need not be conserved at short times in quantum mechanics, according to Heisenberg's

68

Rapid timing studies of black hole binaries in Optical and X-rays: correlated and non-linear variability  

SciTech Connect (OSTI)

In a fast multi-wavelength timing study of black hole X-ray binaries (BHBs), we have discovered correlated optical and X-ray variability in the low/hard state of two sources: GX 339-4 and SWIFT J1753.5-0127. After XTE J1118+480, these are the only BHBs currently known to show rapid (sub-second) aperiodic optical flickering. Our simultaneous VLT/Ultracam and RXTE data reveal intriguing patterns with characteristic peaks, dips and lags down to very short timescales. Simple linear reprocessing models can be ruled out as the origin of the rapid, aperiodic optical power in both sources. A magnetic energy release model with fast interactions between the disk, jet and corona can explain the complex correlation patterns. We also show that in both the optical and X-ray light curves, the absolute source variability r.m.s. amplitude linearly increases with flux, and that the flares have a log-normal distribution. The implication is that variability at both wavelengths is not due to local fluctuations alone, but rather arises as a result of coupling of perturbations over a wide range of radii and timescales. These 'optical and X-ray rms-flux relations' thus provide new constraints to connect the outer and inner parts of the accretion flow, and the jet.

Gandhi, P. [RIKEN Cosmic Radiation Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan (Japan); Dhillon, V. S. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Durant, M.; Shahbaz, T. [Instituto de Astrofisica de Canarias, La Laguna, E38205 Tenerife (Spain); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Makishima, K. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Marsh, T. R. [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom); Miller, J. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Spruit, H. C. [Max-Planck-Institut fuer Astrophysik, Postfach 1317, 85741 Garching (Germany)

2010-07-15T23:59:59.000Z

69

Black holes and thermodynamics  

Science Journals Connector (OSTI)

A black hole of given mass, angular momentum, and charge can have a large number of different unobservable internal configurations which reflect the possible different initial configurations of the matter which collapsed to produce the hole. The logarithm of this number can be regarded as the entropy of the black hole and is a measure of the amount of information about the initial state which was lost in the formation of the black hole. If one makes the hypothesis that the entropy is finite, one can deduce that the black holes must emit thermal radiation at some nonzero temperature. Conversely, the recently derived quantum-mechanical result that black holes do emit thermal radiation at temperature ??2? k c, where ? is the surface gravity, enables one to prove that the entropy is finite and is equal to c3A4 G?, where A is the surface area of the event horizon or boundary of the black hole. Because black holes have negative specific heat, they cannot be in stable thermal equilibrium except when the additional energy available is less than 1/4 the mass of the black hole. This means that the standard statistical-mechanical canonical ensemble cannot be applied when gravitational interactions are important. Black holes behave in a completely random and time-symmetric way and are indistinguishable, for an external observer, from white holes. The irreversibility that appears in the classical limit is merely a statistical effect.

S. W. Hawking

1976-01-15T23:59:59.000Z

70

Evaluation of liquid lift approach to dual gradient  

E-Print Network [OSTI]

the mudline to the rig floor so as to maintain the bottom hole pressure. Several methods have been developed to achieve the dual gradient drilling principle. For this research project, we paid more attention to the liquid lift, dual gradient drilling (riser...

Okafor, Ugochukwu Nnamdi

2009-05-15T23:59:59.000Z

71

Evaluation of liquid lift approach to dual gradient drilling  

E-Print Network [OSTI]

the mudline to the rig floor so as to maintain the bottom hole pressure. Several methods have been developed to achieve the dual gradient drilling principle. For this research project, we paid more attention to the liquid lift, dual gradient drilling (riser...

Okafor, Ugochukwu Nnamdi

2008-10-10T23:59:59.000Z

72

Gradient zone-boundary control in salt-gradient solar ponds  

DOE Patents [OSTI]

A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizeable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

Hull, J.R.

1982-09-29T23:59:59.000Z

73

"Hybrid" Black Holes  

E-Print Network [OSTI]

We discuss a solution of the Einstein equations, obtained by gluing the external Kerr metric and the internal Weyl metric, describing an axisymmetric static vacuum distorted black hole. These metrics are glued at the null surfaces representing their horizons. For this purpose we use the formalism of massive thin null shells. The corresponding solution is called a "hybrid" black hole. The massive null shell has an angular momentum which is the origin of the rotation of the external Kerr spacetime. At the same time, the shell distorts the geometry inside the horizon. The inner geometry of the "hybrid" black hole coincides with the geometry of the interior of a non-rotating Weyl-distorted black hole. Properties of the "hybrid" black holes are briefly discussed.

Valeri P. Frolov; Andrei V. Frolov

2014-12-30T23:59:59.000Z

74

Slim Holes | Open Energy Information  

Open Energy Info (EERE)

Slim Holes Slim Holes Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Slim Holes Details Activities (30) Areas (24) Regions (1) NEPA(6) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Exploration Drilling Parent Exploration Technique: Exploration Drilling Information Provided by Technique Lithology: If core is collected Stratigraphic/Structural: If core is collected Hydrological: Fluid flow and water chemistry Thermal: Thermal gradient or bottom hole temperature Cost Information Low-End Estimate (USD): 100.0010,000 centUSD 0.1 kUSD 1.0e-4 MUSD 1.0e-7 TUSD / foot Median Estimate (USD): 169.8916,989 centUSD 0.17 kUSD 1.6989e-4 MUSD 1.6989e-7 TUSD / foot High-End Estimate (USD): 200.0020,000 centUSD

75

Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD  

SciTech Connect (OSTI)

Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

Mikkelsen, David R. [PPPL; Tanaka, K. [NIFS; Nunami, M. [NIFS; Watanabe, T-H. [Nagoya University; Sugama, H. [NIFS; Yoshinuma, M. [NIFS; Suzuki, Y. [NIFS; Goto, M. [NIFS; Morita, S. [NIFS; Wieland, B. [NIFS; Yamada, I. [NIFS; Yashura, R. [NIFS; Akiyama, T. [NIFS; Pablant, Novimir A. [PPPL

2014-04-01T23:59:59.000Z

76

Ultrafast Photocurrent Measurement of the Escape Time of Electrons and Holes from Carbon Nanotube p-i-n Photodiodes  

E-Print Network [OSTI]

Ultrafast photocurrent measurements are performed on individual carbon nanotube p-i-n photodiodes. The photocurrent response to subpicosecond pulses separated by a variable time delay ?t shows strong photocurrent suppression ...

Gabor, Nathaniel M.

77

Measurement of thermodynamics using gradient flow  

E-Print Network [OSTI]

We analyze bulk thermodynamics and correlation functions of the energy-momentum tensor in pure Yang-Mills gauge theory using the energy-momentum tensor defined by the gradient flow and small flow time expansion. Our results on thermodynamic observables are consistent with those obtained by the conventional integral method. The analysis of the correlation function of total energy supports the energy conservation. It is also addressed that these analyses with gradient flow require less statistics compared with the previous methods. All these results suggest that the energy-momentum tensor can be successfully defined and observed on the lattice with moderate numerical costs with the gradient flow.

Masakiyo Kitazawa; Masayuki Asakawa; Tetsuo Hatsuda; Takumi Iritani; Etsuko Itou; Hiroshi Suzuki

2014-12-15T23:59:59.000Z

78

Field Investigations And Temperature-Gradient Drilling At Marine Corps  

Open Energy Info (EERE)

Investigations And Temperature-Gradient Drilling At Marine Corps Investigations And Temperature-Gradient Drilling At Marine Corps Air-Ground Combat Center (Mcagcc), Twenty-Nine Palms, Ca Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Field Investigations And Temperature-Gradient Drilling At Marine Corps Air-Ground Combat Center (Mcagcc), Twenty-Nine Palms, Ca Details Activities (4) Areas (1) Regions (0) Abstract: The U.S. Navy's Geothermal Program Office (GPO) has been conducting geothermal exploration activities in the Camp Wilson area of Marine Corps Air-Ground Combat Center (MCAGCC), Twenty-nine Palms, CA, for almost two years. Work has included self-potential (SP) surveys, fault structure analyses using LiDAR surveys, and drilling and assessment of five (5) temperature-gradient holes. For several decades the GPO has worked

79

Recurrent policy gradients  

Science Journals Connector (OSTI)

......for recurrent neural networks Recurrent policy gradients Daan Wierstra Alexander Forster...POMDPs) is a challenge as it requires policies with an internal state. Traditional approaches...offer a natural framework for dealing with policy learning using hidden state and require......

Daan Wierstra; Alexander Frster; Jan Peters; Jrgen Schmidhuber

2010-10-01T23:59:59.000Z

80

Thermal Gradient Holes At Fenton Hill HDR Geothermal Area (Purtymun...  

Open Energy Info (EERE)

Valles caldera in order to locate an of high heat flow that would serve as a favorable test site for the HDR concept. Notes Data from these wells are report in Reiter et al....

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Thermal Gradient Holes At Roosevelt Hot Springs Geothermal Area...  

Open Energy Info (EERE)

References S. H. Ward, W. T. Parry, W. P. Nash, W. R. Sill, K. L. Cook, R. B. Smith, D. S. Chapman, F. H. Brown, J. A. Whelan, J. R. Bowman (1978) A Summary of the...

82

Thermal Gradient Holes At Long Valley Caldera Geothermal Area...  

Open Energy Info (EERE)

Regime of Long Valley Caldera. Journal of Geophysical Research. 81(5):763-768. J.L. Smith,R.W. Rex. 1977. Drilling results from eastern Long Valley Caldera. () : American...

83

Thermal Gradient Holes At Long Valley Caldera Geothermal Area...  

Open Energy Info (EERE)

studies, and seem to prove useful in most cases (Flexser, 1991; Goff et al., 1991; Smith and Suemnicht, 1991). Results from these studies are also summarized in Sorey et al....

84

Thermodynamics of Lifshitz black holes  

Science Journals Connector (OSTI)

We apply the recently extended conserved Killing charge definition of Abbott-Deser-Tekin formalism to compute, for the first time, the energies of analytic Lifshitz black holes in higher dimensions. We then calculate the temperature and the entropy of this large family of solutions, and study and discuss the first law of black hole thermodynamics. Along the way we also identify the possible critical points of the relevant quadratic curvature gravity theories. Separately, we also apply the generalized Killing charge definition to compute the energy and the angular momentum of the warped AdS3 black hole solution of the three-dimensional new massive gravity theory.

Deniz Olgu Devecio?lu and zgr Sar?o?lu

2011-06-23T23:59:59.000Z

85

Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing  

E-Print Network [OSTI]

We provide details of the first implementation of a non-linear conjugate gradient method for Landau and Coulomb gauge fixing with Fourier acceleration. We find clear improvement over the Fourier accelerated steepest descent method, with the average time taken for the algorithm to converge to a fixed, high accuracy, being reduced by a factor of 2 to 4.

R. J. Hudspith

2014-05-22T23:59:59.000Z

86

Steep Gradient Flume | Open Energy Information  

Open Energy Info (EERE)

Steep Gradient Flume Steep Gradient Flume Jump to: navigation, search Basic Specifications Facility Name Steep Gradient Flume Overseeing Organization University of Iowa Hydrodynamic Testing Facility Type Flume Length(m) 20.1 Beam(m) 0.9 Depth(m) 0.5 Cost(per day) Contact POC Special Physical Features Tilting flume from -1.5 to +16% slope; <3mm sedimentation recirculation capabilities; instrumentation rails Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Recirculating Yes Wind Capabilities Wind Capabilities None Control and Data Acquisition Cameras Yes Number of Color Cameras 1 Available Sensors Acoustics, Flow, Thermal, Turbulence, Velocity Data Generation Capability Real-Time Yes

87

Black hole lasers  

Science Journals Connector (OSTI)

High frequency dispersion does not alter the low frequency spectrum of Hawking radiation from a single black hole horizon, whether the dispersion entails subluminal or superluminal group velocities. We show here that in the presence of an inner horizon as well as an outer horizon the superluminal case differs dramatically however. The negative energy partners of Hawking quanta return to the outer horizon and stimulate more Hawking radiation if the field is bosonic or suppress it if the field is fermionic. This process leads to exponential growth or damping of the radiated flux and correlations among the quanta emitted at different times, unlike in the usual Hawking effect. These phenomena may be observable in condensed matter black hole analogues that exhibit superluminal dispersion.

Steven Corley and Ted Jacobson

1999-05-17T23:59:59.000Z

88

Photo of the Week: The Alternating Gradient Synchrotron | Department of  

Broader source: Energy.gov (indexed) [DOE]

The Alternating Gradient Synchrotron The Alternating Gradient Synchrotron Photo of the Week: The Alternating Gradient Synchrotron March 11, 2013 - 6:00pm Addthis Since 1960, the Alternating Gradient Synchrotron (AGS) has been one of the world's premiere particle accelerators, well known for the three Nobel Prizes won as a result of research performed there. The AGS name is derived from the concept of alternating gradient focusing, in which the field gradients of the accelerator's 240 magnets are successively alternated inward and outward, permitting particles to be propelled and focused in both the horizontal and vertical plane at the same time. In this 1958 photo, giant magnets await installation into the AGS accelerator ring tunnel at Brookhaven National Laboratory. | Photo courtesy of Brookhaven National Laboratory.

89

Photo of the Week: The Alternating Gradient Synchrotron | Department of  

Broader source: Energy.gov (indexed) [DOE]

The Alternating Gradient Synchrotron The Alternating Gradient Synchrotron Photo of the Week: The Alternating Gradient Synchrotron March 11, 2013 - 6:00pm Addthis Since 1960, the Alternating Gradient Synchrotron (AGS) has been one of the world's premiere particle accelerators, well known for the three Nobel Prizes won as a result of research performed there. The AGS name is derived from the concept of alternating gradient focusing, in which the field gradients of the accelerator's 240 magnets are successively alternated inward and outward, permitting particles to be propelled and focused in both the horizontal and vertical plane at the same time. In this 1958 photo, giant magnets await installation into the AGS accelerator ring tunnel at Brookhaven National Laboratory. | Photo courtesy of Brookhaven National Laboratory.

90

Energy in density gradient  

E-Print Network [OSTI]

Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...

Vranjes, J

2015-01-01T23:59:59.000Z

91

Absorption cross section of RN black hole  

E-Print Network [OSTI]

The behavior of a charged scalar field in the RN black hole space time is studied using WKB approximation. In the present work it is assumed that matter waves can get reflected from the event horizon. Using this effect, the Hawking temperature and the absorption cross section for RN black hole placed in a charged scalar field are calculated. The absorption cross section $\\sigma _{abs}$ is found to be inversely proportional to square of the Hawking temperature of the black hole.

Sini R.; V. C. Kuriakose

2007-08-23T23:59:59.000Z

92

What is the topology of a Schwarzschild black hole?  

E-Print Network [OSTI]

We investigate the topology of Schwarzschild's black hole through the immersion of this space-time in spaces of higher dimension. Through the immersions of Kasner and Fronsdal we calculate the extension of the Schwarzschild's black hole.

Edmundo M. Monte

2011-11-24T23:59:59.000Z

93

High-gradient compact linear accelerator  

DOE Patents [OSTI]

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

Carder, Bruce M. (205 Rogue River Hwy., Gold Hill, OR 97525)

1998-01-01T23:59:59.000Z

94

High-gradient compact linear accelerator  

DOE Patents [OSTI]

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter. 10 figs.

Carder, B.M.

1998-05-26T23:59:59.000Z

95

Gradient Resources | Open Energy Information  

Open Energy Info (EERE)

Resources Resources Jump to: navigation, search Logo: Gradient Resources Name Gradient Resources Address 9670 Gateway Drive, Suite 200 Place Reno, Nevada Zip 89521 Sector Geothermal energy Year founded 1991 Company Type For Profit Phone number (775) 284-8842 Website http://www.gradient.com/ Region Rockies Area References Gradient Resources Website[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! Gradient Resources is a company based in Reno, Nevada. Gradient Resources is engaged in the exploration and development of geothermal resources as well as the construction, ownership and operation of geothermal power plants. The Company is headquartered in Reno, Nevada with a regional office, drilling operations center, and well-cementing

96

Hierarchically deflated conjugate gradient  

E-Print Network [OSTI]

We present a multi-level algorithm for the solution of five dimensional chiral fermion formulations, including domain wall and Mobius Fermions. The algorithm operates on the red-black preconditioned Hermitian operator, and directly accelerates conjugate gradients on the normal equations. The coarse grid representation of this matrix is next-to-next-to-next-to-nearest neighbour and multiple algorithmic advances are introduced, which help minimise the overhead of the coarse grid. The treatment of the coarse grids is purely four dimensional, and the bulk of the coarse grid operations are nearest neighbour. The intrinsic cost of most of the coarse grid operations is therefore comparable to those for the Wilson case. We also document the implementation of this algorithm in the BAGEL/Bfm software package and report on the measured performance gains the algorithm brings to simulations at the physical point on IBM BlueGene/Q hardware.

P A Boyle

2014-02-11T23:59:59.000Z

97

Gradient Sliding for Composite Optimization  

E-Print Network [OSTI]

Noname manuscript No. (will be inserted by the editor). Gradient Sliding for Composite Optimization. Guanghui Lan the date of receipt and acceptance should...

2014-06-11T23:59:59.000Z

98

Geodesics and Geodesic Deviation in static Charged Black Holes  

E-Print Network [OSTI]

The radial motion along null geodesics in static charged black hole space-times, in particular, the Reissner-Nordstr\\"om and stringy charged black holes are studied. We analyzed the properties of the effective potential. The circular photon orbits in these space-times are investigated. We found that the radius of circular photon orbits in both charged black holes are different and differ from that given in Schwarzschild space-time. We studied the physical effects of the gravitational field between two test particles in stringy charged black hole and compared the results with that given in Schwarzschild and Reissner-Nordstr\\"om black holes.

Ragab M. Gad

2010-03-03T23:59:59.000Z

99

Black Hole Horizons and Black Hole Thermodynamics.  

E-Print Network [OSTI]

??This work investigates how black holes can be described in terms of different definitions of horizons. Global definitions in terms of event horizons and Killing (more)

Nielsen, Alex

2007-01-01T23:59:59.000Z

100

Information loss in black holes  

Science Journals Connector (OSTI)

The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with nontrivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.

S. W. Hawking

2005-10-18T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

High field gradient particle accelerator  

DOE Patents [OSTI]

A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

Nation, J.A.; Greenwald, S.

1989-05-30T23:59:59.000Z

102

High field gradient particle accelerator  

DOE Patents [OSTI]

A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

Nation, John A. (Ithaca, NY); Greenwald, Shlomo (Haifa, IL)

1989-01-01T23:59:59.000Z

103

Energy on black hole spacetimes  

E-Print Network [OSTI]

We consider the issue of defining energy for test particles on a background black hole spacetime. We revisit the different notions of energy as defined by different observers. The existence of a time-like isometry allows for the notion of a total conserved energy to be well defined, and subsequently the notion of a gravitational potential energy is also meaningful. We then consider the situation in which the test particle is adsorbed by the black hole, and analyze the energetics in detail. In particular, we show that the notion of horizon energy es defined by the isolated horizons formalism provides a satisfactory notion of energy compatible with the particle's conserved energy. As another example, we comment a recent proposal to define energy of the black hole as seen by an observer at rest. This account is intended to be pedagogical and is aimed at the level of and as a complement to the standard textbooks on the subject.

Alejandro Corichi

2012-07-18T23:59:59.000Z

104

Correlated Knowledge Gradients: Example alternatives  

E-Print Network [OSTI]

Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0;Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0 num measurements log(KGfactor) 0 10 20 30 0 0.5 1 1.5 2 num measurements opportunitycost #12;Correlated Knowledge

Keinan, Alon

105

Black Hole Thermodynamics and Electromagnetism  

E-Print Network [OSTI]

We show a strong parallel between the Hawking, Beckenstein black hole Thermodynamics and electromagnetism: When the gravitational coupling constant transform into the electromagnetic coupling constant, the Schwarzchild radius, the Beckenstein temperature, the Beckenstein decay time and the Planck mass transform to respectively the Compton wavelength, the Hagedorn temperature, the Compton time and a typical elementary particle mass. The reasons underlying this parallalism are then discussed in detail.

Burra G. Sidharth

2005-07-15T23:59:59.000Z

106

Black Hole Chemistry  

E-Print Network [OSTI]

The mass of a black hole has traditionally been identified with its energy. We describe a new perspective on black hole thermodynamics, one that identifies the mass of a black hole with chemical enthalpy, and the cosmological constant as thermodynamic pressure. This leads to an understanding of black holes from the viewpoint of chemistry, in terms of concepts such as Van der Waals fluids, reentrant phase transitions, and triple points. Both charged and rotating black holes exhibit novel chemical-type phase behaviour, hitherto unseen.

David Kubiznak; Robert B. Mann

2014-04-08T23:59:59.000Z

107

The 1983 Temperature Gradient and Heat Flow Drilling Project for the State of Washington  

SciTech Connect (OSTI)

During the Summer of 1983, the Washington Division of Geology and Earth Resources carried out a three-hole drilling program to collect temperature gradient and heat flow information near potential geothermal resource target areas. The project was part of the state-coupled US Department of Energy Geothermal Program. Richardson Well Drilling of Tacoma, Washington was subcontracted through the State to perform the work. The general locations of the project areas are shown in figure 1. The first hole, DNR 83-1, was located within the Green River valley northwest of Mount St. Helens. This site is near the Green River Soda Springs and along the projection of the Mount St. Helens--Elk Lake seismic zone. The other two holes were drilled near Mount Baker. Hole DNR 83-3 was sited about 1/4 km west of the Baker Hot Springs, 10.5 km east of Mount Baker, while hole DNR 83-5 was located along Rocky Creek in the Sulphur Creek Valley. The Rocky Creek hole is about 10 km south-southwest of the peak. Two other holes, DNR 83-2 and DNR 83-4, were located on the north side of the Sulphur Creek Valley. Both holes were abandoned at early stages of drilling because of deep overburden and severe caving problems. The sites were apparently located atop old landslide deposits.

Korosec, Michael A.

1983-11-01T23:59:59.000Z

108

1983 temperature gradient and heat flow drilling project for the State of Washington  

SciTech Connect (OSTI)

During the Summer of 1983, a three-hole drilling program was carried out to collect temperature gradient and heat flow information near potential geothermal resource target areas. The general locations of the project areas are shown. The first hole, DNR 83-1, was located within the Green River valley northwest of Mount St. Helens. This site is near the Green River Soda Springs and along the projection of the Mount St. Helens - Elk Lake seismic zone. The other two holes were drilled near Mount Baker. Hole DNR 83-3 was sited about 1/4 km west of the Baker Hot Springs, 10.5 km east of Mount Baker, while hole DNR 83-5 was located along Rocky Creek in the Sulphur Creek Valley. The Rocky Creek hole is about 10 km south-southwest of the peak. Two other holes, DNR 83-2 and DNR 83-4, were located on the north side of the Sulphur Creek Valley. Both holes were abandoned at early stages of drilling because of deep overburden and severe caving problems. The sites were apparently located atop old landslide deposits.

Korosec, M.A.

1983-11-01T23:59:59.000Z

109

Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling  

E-Print Network [OSTI]

We show that there is a classical metric satisfying the Einstein equations outside a finite spacetime region where matter collapses into a black hole and then emerges from a white hole. We compute this metric explicitly. We show how quantum theory determines the (long) time for the process to happen. A black hole can thus quantum-tunnel into a white hole. For this to happen, quantum gravity should affect the metric also in a small region outside the horizon: we show that contrary to what is commonly assumed, this is not forbidden by causality or by the semiclassical approximation, because quantum effects can pile up over a long time. This scenario alters radically the discussion on the black hole information puzzle.

Hal M. Haggard; Carlo Rovelli

2014-07-06T23:59:59.000Z

110

Solar energy storage by salinity gradient solar pond: Pilot plant construction and gradient control  

Science Journals Connector (OSTI)

An experimental solar pond pilot plant was constructed in Solvay-Martorell, facilities, Catalonia (NE part of the Iberian Peninsula) to capture and store solar energy. The body of the pond is a cylindrical reinforced concrete tank, 3m height, 8m diameter and total area of 50m2. Salinity and thermal gradient were properly established by using the salinity distribution methodology. The gradient in the pond was maintained by feeding salt (NaCl) through a cylindrical salt charger to the bottom at a height of 80cm from the pond floor. Continuous surface washing using tap water supply maintained the salinity of the top convective layer at a low level and compensate loses by evaporation. An acidification method by addition of \\{HCl\\} at different heights was used to control the clarity of the pond. The salinity gradient was fully established on 30 September 2009 and has been maintained until the date. After winter time (February 2010), the pond warms up and the temperature increased continuously until it reached its maximum (55C) in August 2010. The salinity gradient observed great stability after one year of continuous control and maintenance and under different weather conditions.

Csar Valderrama; Oriol Gibert; Jordina Arcal; Pau Solano; Aliakbar Akbarzadeh; Enric Larrotcha; Jos Luis Cortina

2011-01-01T23:59:59.000Z

111

Some remarks on black hole thermodynamics  

E-Print Network [OSTI]

Two thermodynamic "paradoxes" of black hole physics are re-examined. The first is that there is a thermal instability involving two coupled blackbody cavities containing two black holes, and second is that a classical black hole can swallow up entropy in the form of ambient blackbody photons without increasing its mass. The resolution of the second paradox by Bekenstein and by Hawking is re-visited. The link between Hawking radiation and Wigner's superluminal tunneling time is discussed using two equivalent Feynman diagrams, and Feynman's re-interpretation principle.

R. Y. Chiao

2010-12-27T23:59:59.000Z

112

Lattice Black Holes  

E-Print Network [OSTI]

We study the Hawking process on lattices falling into static black holes. The motivation is to understand how the outgoing modes and Hawking radiation can arise in a setting with a strict short distance cutoff in the free-fall frame. We employ two-dimensional free scalar field theory. For a falling lattice with a discrete time-translation symmetry we use analytical methods to establish that, for Killing frequency $\\omega$ and surface gravity $\\kappa$ satisfying $\\kappa\\ll\\omega^{1/3}\\ll 1$ in lattice units, the continuum Hawking spectrum is recovered. The low frequency outgoing modes arise from exotic ingoing modes with large proper wavevectors that "refract" off the horizon. In this model with time translation symmetry the proper lattice spacing goes to zero at spatial infinity. We also consider instead falling lattices whose proper lattice spacing is constant at infinity and therefore grows with time at any finite radius. This violation of time translation symmetry is visible only at wavelengths comparable to the lattice spacing, and it is responsible for transmuting ingoing high Killing frequency modes into low frequency outgoing modes.

Steven Corley; Ted Jacobson

1998-03-26T23:59:59.000Z

113

Uniformly accelerated black holes  

Science Journals Connector (OSTI)

The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness of the black hole horizon, (ii) by using standard black hole thermodynamics we show that accelerated black holes have a higher Hawking temperature than Unruh temperature of the accelerated frame, and (iii) the usual upper bound on the product of the mass and acceleration parameters (<1/27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes.

Patricio S. Letelier and Samuel R. Oliveira

2001-08-24T23:59:59.000Z

114

Gas Exchange, Partial Pressure Gradients,  

E-Print Network [OSTI]

Gas Exchange, Partial Pressure Gradients, and the Oxygen Window Johnny E. Brian, Jr., M of circulatory and gas transport physiology, and the best place to start is with normobaric physiology. LIFE affect the precise gas exchange occurring in individual areas of the lungs and body tissues. To make

Riba Sagarra, Jaume

115

The Extended Finite Element Method for High Gradient Solutions  

E-Print Network [OSTI]

Outline Enrichment functions for high gradient solutions Motivation High gradient inside the domain (Shocks) High gradient at the boundary (boundary layers) Optimal set of enrichment functions Numerical for high gradient solutions Outline Enrichment functions for high gradient solutions Motivation High

116

Accreting Black Holes  

E-Print Network [OSTI]

I outline the theory of accretion onto black holes, and its application to observed phenomena such as X-ray binaries, active galactic nuclei, tidal disruption events, and gamma-ray bursts. The dynamics as well as radiative signatures of black hole accretion depend on interactions between the relatively simple black-hole spacetime and complex radiation, plasma and magnetohydrodynamical processes in the surrounding gas. I will show how transient accretion processes could provide clues to these interactions. Larger global magnetohydrodynamic simulations as well as simulations incorporating plasma microphysics and full radiation hydrodynamics will be needed to unravel some of the current mysteries of black hole accretion.

Begelman, Mitchell C

2014-01-01T23:59:59.000Z

117

Black Hole Evaporation in an Expanding Universe  

E-Print Network [OSTI]

We calculate the quantum radiation power of black holes which are asymptotic to the Einstein-de Sitter universe at spatial and null infinities. We consider two limiting mass accretion scenarios, no accretion and significant accretion. We find that the radiation power strongly depends on not only the asymptotic condition but also the mass accretion scenario. For the no accretion case, we consider the Einstein-Straus solution, where a black hole of constant mass resides in the dust Friedmann universe. We find negative cosmological correction besides the expected redshift factor. This is given in terms of the cubic root of ratio in size of the black hole to the cosmological horizon, so that it is currently of order $10^{-5} (M/10^{6}M_{\\odot})^{1/3} (t/14 {Gyr})^{-1/3}$ but could have been significant at the formation epoch of primordial black holes. Due to the cosmological effects, this black hole has not settled down to an equilibrium state. This cosmological correction may be interpreted in an analogy with the radiation from a moving mirror in a flat spacetime. For the significant accretion case, we consider the Sultana-Dyer solution, where a black hole tends to increase its mass in proportion to the cosmological scale factor. In this model, we find that the radiation power is apparently the same as the Hawking radiation from the Schwarzschild black hole of which mass is that of the growing mass at each moment. Hence, the energy loss rate decreases and tends to vanish as time proceeds. Consequently, the energy loss due to evaporation is insignificant compared to huge mass accretion onto the black hole. Based on this model, we propose a definition of quasi-equilibrium temperature for general conformal stationary black holes.

Hiromi Saida; Tomohiro Harada; Hideki Maeda

2007-05-28T23:59:59.000Z

118

Unified first law of black-hole dynamics and relativistic thermodynamics  

E-Print Network [OSTI]

A unified first law of black-hole dynamics and relativistic thermodynamics is derived in spherically symmetric general relativity. This equation expresses the gradient of the active gravitational energy E according to the Einstein equation, divided into energy-supply and work terms. Projecting the equation along the flow of thermodynamic matter and along the trapping horizon of a blackhole yield, respectively, first laws of relativistic thermodynamics and black-hole dynamics. In the black-hole case, this first law has the same form as the first law of black-hole statics, with static perturbations replaced by the derivative along the horizon. There is the expected term involving the area and surface gravity, where the dynamic surface gravity is defined as in the static case but using the Kodama vector and trapping horizon. This surface gravity vanishes for degenerate trapping horizons and satisfies certain expected inequalities involving the area and energy. In the thermodynamic case, the quasi-local first law has the same form, apart from a relativistic factor, as the classical first law of thermodynamics, involving heat supply and hydrodynamic work, but with E replacing the internal energy. Expanding E in the Newtonian limit shows that it incorporates the Newtonian mass, kinetic energy, gravitational potential energy and thermal energy. There is also a weak type of unified zeroth law: a Gibbs-like definition of thermal equilibrium requires constancy of an effective temperature, generalising the Tolman condition and the particular case of Hawking radiation, while gravithermal equilibrium further requires constancy of surface gravity. Finally, it is suggested that the energy operator of spherically symmetric quantum gravity is determined by the Kodama vector, which encodes a dynamic time related to E.

Sean A. Hayward

1997-10-20T23:59:59.000Z

119

Conserved quantities in a black hole collision  

E-Print Network [OSTI]

The Newman-Penrose constants of the spacetime corresponding to the development of the Brill-Lindquist initial data are calculated by making use of a particular representation of spatial infinity due to H. Friedrich. The Brill-Lindquist initial data set represents the head-on collision of two non-rotating black holes. In this case one non-zero constant is obtained. Its value is given in terms of the product of the individual masses of the black holes and the square of a distance parameter separating the two black holes. This constant retains its value all along null infinity, and therefore it provides information about the late time evolution of the collision process. In particular, it is argued that the magnitude of the constants provides information about the amount of residual radiation contained in the spacetime after the collision of the black holes.

S. Dain; J. A. Valiente-Kroon

2001-05-28T23:59:59.000Z

120

Temperature gradients in a portion of Michigan: a review of the usefulness of data from the AAPG geothermal survey of North America  

SciTech Connect (OSTI)

Temperature gradient data derived from drill holes in an east-west zone through the center of the southern peninsula of Michigan are analyzed. The purpose of this work is to investigate possible problems in utilizing the American Association of Petroleum Geologists data base. Michigan was chosen because a review of that State's geothermal potential shows inconsistencies between gradients from shallow wells and nearby deeper wells and because the geology of the State is relativey simple. The structure and stratigraphy are discussed because an understanding of Michigan basin geology makes it easier to predict the influence of lithology on the basin's geothermal gradients. Explanations for elevated gradients are reviewed. (MHR)

Vaught, T.L.

1980-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Salinity Gradient Energy at River Mouths  

Science Journals Connector (OSTI)

Salinity Gradient Energy at River Mouths ... River mouths are potentially abundant locations for the exploitation of the clean and renewable salinity gradient energy (SGE) as here perpetually fresh water mixes with saline seawater. ...

Oscar Alvarez-Silva; Christian Winter; Andres F. Osorio

2014-09-03T23:59:59.000Z

122

Revisiting an Old Concept: The Gradient Wind  

Science Journals Connector (OSTI)

The gradient wind is defined as a horizontal wind having the same direction as the geostrophic wind but with a magnitude consistent with a balance of three forces: the pressure gradient force, the Coriolis force, and the centrifugal force arising ...

Keith F. Brill

2014-04-01T23:59:59.000Z

123

SS433a massive black hole?  

Science Journals Connector (OSTI)

... thin ring in a circular orbit at radius R = r GM/c2 around a Schwarzschild black hole of mass M, the two emission peaks will be at wavelengths given ... we would expect the profiles of the emission peaks at any given time to be mirror images of each other (at least on timescales longer than the orbital time). ...

R. J. TERLEVICH; J. E. PRINGLE

1979-04-19T23:59:59.000Z

124

A Quantum Material Model of Static Schwarzschild Black Holes  

E-Print Network [OSTI]

A quantum-mechanical prescription of static Einstein field equation is proposed in order to construct the matter-metric eigen-states in the interior of a static Schwarzschild black hole where the signature of space-time is chosen as (--++). The spectrum of the quantum states is identified to be the integral multiples of the surface gravity. A statistical explanation of black hole entropy is given and a quantisation rule for the masses of Schwarzschild black holes is proposed.

S. -T. Sung

1997-03-16T23:59:59.000Z

125

Entropy of quasiblack holes  

SciTech Connect (OSTI)

We trace the origin of the black hole entropy S, replacing a black hole by a quasiblack hole. Let the boundary of a static body approach its own gravitational radius, in such a way that a quasihorizon forms. We show that if the body is thermal with the temperature taking the Hawking value at the quasihorizon limit, it follows, in the nonextremal case, from the first law of thermodynamics that the entropy approaches the Bekenstein-Hawking value S=A/4. In this setup, the key role is played by the surface stresses on the quasihorizon and one finds that the entropy comes from the quasihorizon surface. Any distribution of matter inside the surface leads to the same universal value for the entropy in the quasihorizon limit. This can be of some help in the understanding of black hole entropy. Other similarities between black holes and quasiblack holes such as the mass formulas for both objects had been found previously. We also discuss the entropy for extremal quasiblack holes, a more subtle issue.

Lemos, Jose P. S.; Zaslavskii, Oleg B. [Centro Multidisciplinar de Astrofisica-CENTRA, Departamento de Fisica, Instituto Superior Tecnico-IST, Universidade Tecnica de Lisboa-UTL, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Astronomical Institute of Kharkov, V. N. Karazin National University, 35 Sumskaya Street, Kharkov, 61022 (Ukraine)

2010-03-15T23:59:59.000Z

126

Preparation and characterization of gradient polymer films  

SciTech Connect (OSTI)

Gradient polymers are multicomponent polymers whose chemical constitution varies with depth in the sample. Although these polymers may possess unique mechanical, optical, and barrier properties they remain relatively unexplored. This work is a study of the preparation of gradient polymers by sequential exposure of films to a diffusing monomer followed by electron beam irradiation. Initial experiments involved immersion of poly(vinyl chloride) (PVC) films in styrene or n-butyl methacrylate (BMA) for various time periods followed by irradiation with 1 or 10 megarads of accelerated electrons. A significant amount of poly(n-butyl methacrylate) (PBMA) formed in PVC/BMA systems, but little polystyrene could be found in the PVC/styrene films. A second set of experiments involved immersion of PVC and polyethylene (PE) films in BMA for 20, 40, 60, and 720 minutes followed by irradiation with 10 megarads of electrons. These films were then characterized using optical microscopy, quantitative transmission Fourier transform infrared spectroscopy (FTIR), and a depth profiling procedure based on quantitative attenuated total reflection (ATR) FTIR. It was concluded that the mechanism of PBMA formation in the polyethylene films was a result of events immediately following irradiation. Atmospheric oxygen diffusing into irradiated films trapped free radicals at the film surfaces. This was followed by storage in an evacuated desiccator where unintentional exposure to BMA vapor took place. This BMA reacted with free radicals that remained within the film cores, polymerizing to PBMA.

Smith, S.C.

1987-01-01T23:59:59.000Z

127

Bayesian Policy Gradient and Actor-Critic Algorithms Bayesian Policy Gradient and Actor-Critic Algorithms  

E-Print Network [OSTI]

Bayesian Policy Gradient and Actor-Critic Algorithms Bayesian Policy Gradient and Actor Yaakov Engel yakiengel@gmail.com Editor: Abstract Policy gradient methods are reinforcement learning algorithms that adapt a param- eterized policy by following a performance gradient estimate. Many

Paris-Sud XI, Université de

128

Electrical resistance of metallized via?holes  

Science Journals Connector (OSTI)

The resistance of a via?hole laser?drilled through an alumina substrate depends on the hole geometry the type of probe the deposition technique and the properties of the film. If the walls of the hole constitute a truncated cone the resistance is R s/?[ln(d 2/d 1)]{1/4 + [h/(d 2 ? d 1)]2}1/2 where R s is the sheet resistance h is the substrate thickness and d 1 and d 2 are the diameters. Increasing the larger diameter helps by (a) reducing the rim?to?rim resistance (b) reducing the spreading resistance and (c) making the walls more accessible for metallization. A four?point probe on the other hand measures the rim?to?rim resistance as approximately (R s/?) ln cosh (h/d) where d is an average diameter. If the hole is partially bare the four?point reading will depend on probe orientation. A comparison of calculation and measurement indicates R s in the hole to be between two and forty times R s outside depending on the thickness. Electrical probing of broken?open holes showed this to be due to thickness differences not roughness or ledge resistance.

Peter M. Hall

1975-01-01T23:59:59.000Z

129

Black Holes as Conformal Field Theories on Horizons  

E-Print Network [OSTI]

We show that any nonextreme black hole can be described by a state with $L_0=E_R$ in a $D=2$ chiral conformal field theory with central charge $c=12E_R$ where $E_R$ is the dimensionless Rindler energy of the black hole. The theory lives in the very near horizon region, i.e. around the origin of Rindler space. Black hole hair is the momentum along the Euclidean dimensionless Rindler time direction. As evidence, we show that $D$--dimensional Schwarzschild black holes and $D=2$ dilatonic ones that are obtained from them by spherical reduction are described by the same conformal field theory states.

Halyo, Edi

2015-01-01T23:59:59.000Z

130

Primordial Black Hole Evolution in Tensor-Scalar Cosmology  

Science Journals Connector (OSTI)

A perturbative analysis shows that black holes do not remember the value of the scalar field ? at the time they formed if ? changes in tensor-scalar cosmology. Moreover, even when the black hole mass in the Einstein frame is approximately unaffected by the changing of ?, in the Jordan-Fierz frame the mass increases. This mass increase requires a reanalysis of the evaporation of primordial black holes in tensor-scalar cosmology. It also implies that there could have been a significant magnification of the (Jordan-Fierz frame) mass of primordial black holes.

Ted Jacobson

1999-10-04T23:59:59.000Z

131

RHIC | Black Holes?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Black Holes at RHIC? Black Holes at RHIC? Before RHIC began operations in 2000, some were concerned that it would produce black holes that would threaten the earth. Here's why those concerns were unfounded. Committee Review of Speculative "Disaster Scenarios" at RHIC In July 1999, Brookhaven Lab Director John Marburger convened a committee of distinguished physicists to write a comprehensive report on the arguments that address the safety of speculative disaster scenarios at RHIC. The scenarios are: Creation of a black hole that would "eat" ordinary matter. Initiation of a transition to a new, more stable universe. Formation of a "strangelet" that would convert ordinary matter to a new form. jaffee "We conclude that there are no credible mechanisms for catastrophic

132

Charged Schrodinger black holes  

E-Print Network [OSTI]

We construct charged and rotating asymptotically Schrdinger black hole solutions of type IIB supergravity. We begin by obtaining a closed-form expression for the null Melvin twist of a broad class of type IIB backgrounds, ...

Adams, Allan

133

Holes in Spectral Lines  

E-Print Network [OSTI]

The decay of an atom in the presence of a static perturbation is investigated. The perturbation couples a decaying state with a nondecaying state. A "hole" appears in the emission line at a frequency equal to the frequency ...

Fontana, Peter R.; Srivastava, Rajendra P.

1973-06-01T23:59:59.000Z

134

A Comparison of Intermediate Mass Black Hole Candidate ULXs and Stellar-Mass Black Holes  

E-Print Network [OSTI]

Cool thermal emission components have recently been revealed in the X-ray spectra of a small number of ultra-luminous X-ray (ULX) sources with L_X > 1 E+40 erg/s in nearby galaxies. These components can be well fitted with accretion disk models, with temperatures approximately 5-10 times lower than disk temperatures measured in stellar-mass Galactic black holes when observed in their brightest states. Because disk temperature is expected to fall with increasing black hole mass, and because the X-ray luminosity of these sources exceeds the Eddington limit for 10 Msun black holes (L_Edd = 1.3 E+39 erg/s), these sources are extremely promising intermediate-mass black hole candidates (IMBHCs). In this Letter, we directly compare the inferred disk temperatures and luminosities of these ULXs, with the disk temperatures and luminosities of a number of Galactic black holes. The sample of stellar-mass black holes was selected to include different orbital periods, companion types, inclinations, and column densities. These ULXs and stellar-mass black holes occupy distinct regions of a L_X -- kT diagram, suggesting these ULXs may harbor IMBHs. We briefly discuss the important strengths and weaknesses of this interpretation.

J. M. Miller; A. C. Fabian; M. C. Miller

2004-06-29T23:59:59.000Z

135

High gradient lens for charged particle beam  

DOE Patents [OSTI]

Methods and devices enable shaping of a charged particle beam. A dynamically adjustable electric lens includes a series of alternating a series of alternating layers of insulators and conductors with a hollow center. The series of alternating layers when stacked together form a high gradient insulator (HGI) tube to allow propagation of the charged particle beam through the hollow center of the HGI tube. A plurality of transmission lines are connected to a plurality of sections of the HGI tube, and one or more voltage sources are provided to supply an adjustable voltage value to each transmission line of the plurality of transmission lines. By changing the voltage values supplied to each section of the HGI tube, any desired electric field can be established across the HGI tube. This way various functionalities including focusing, defocusing, acceleration, deceleration, intensity modulation and others can be effectuated on a time varying basis.

Chen, Yu-Jiuan

2014-04-29T23:59:59.000Z

136

On Black Hole Entropy  

E-Print Network [OSTI]

Two techniques for computing black hole entropy in generally covariant gravity theories including arbitrary higher derivative interactions are studied. The techniques are Wald's Noether charge approach introduced recently, and a field redefinition method developed in this paper. Wald's results are extended by establishing that his local geometric expression for the black hole entropy gives the same result when evaluated on an arbitrary cross-section of a Killing horizon (rather than just the bifurcation surface). Further, we show that his expression for the entropy is not affected by ambiguities which arise in the Noether construction. Using the Noether charge expression, the entropy is evaluated explicitly for black holes in a wide class of generally covariant theories. Further, it is shown that the Killing horizon and surface gravity of a stationary black hole metric are invariant under field redefinitions of the metric of the form $\\bar{g}_{ab}\\equiv g_{ab} + \\Delta_{ab}$, where $\\Delta_{ab}$ is a tensor field constructed out of stationary fields. Using this result, a technique is developed for evaluating the black hole entropy in a given theory in terms of that of another theory related by field redefinitions. Remarkably, it is established that certain perturbative, first order, results obtained with this method are in fact {\\it exact}. The possible significance of these results for the problem of finding the statistical origin of black hole entropy is discussed.}

Ted Jacobson; Gungwon Kang; Robert C. Myers

1994-01-03T23:59:59.000Z

137

SYNTHESIS Evolution and the latitudinal diversity gradient: speciation, extinction and biogeography  

E-Print Network [OSTI]

, USA 7 Center for Marine Biodiversity and Conservation, Scripps Insti- tution of Oceanography and Michael Turelli18 Abstract A latitudinal gradient in biodiversity has existed since before the time gradient represents a major challenge to future research. Keywords Biodiversity, biotic interactions

Roy, Kaustuv

138

Slim Holes At Blue Mountain Area (Fairbank Engineering, 2009) | Open Energy  

Open Energy Info (EERE)

Fairbank Engineering, 2009) Fairbank Engineering, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Slim Holes At Blue Mountain Area (Fairbank Engineering, 2009) Exploration Activity Details Location Blue Mountain Area Exploration Technique Slim Holes Activity Date Usefulness useful DOE-funding Unknown Notes DEEP BLUE No.1, the first slim geothermal observation test hole at Blue Mountain, was drilled under a cost-share program between the DOE and Noramex, under the DOE's Geothermal Resource Exploration and Definition (GRED) program, (Noramex Corp., 2002). The hole was sited to test an area of projected high temperature at depth from gradients measured in shallow holes drilled in the central part of the lease area (Figure 3.1), and to test an area of low apparent resistivity interpreted to reflect possible

139

Schwarzschild black hole in dark energy background  

E-Print Network [OSTI]

In this paper we present an exact solution of Einstein's field equations describing the Schwarzschild black hole in dark energy background. It is also regarded as an embedded solution that the Schwarzschild black hole is embedded into the dark energy space producing Schwarzschild-dark energy black hole. It is found that the space-time geometry of Schwarzschild-dark energy solution is non-vacuum Petrov type $D$ in the classification of space-times. We study the energy conditions (like weak, strong and dominant conditions) for the energy-momentum tensor of the Schwarzschild-dark energy solution. We also find that the energy-momentum tensor of the Schwarzschild-dark energy solution violates the strong energy condition due to the negative pressure leading to a repulsive gravitational force of the matter field in the space-time. It is shown that the time-like vector field for an observer in the Schwarzschild-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity and the area of the horizons for the Schwarzschild-dark energy black hole.

Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh

2014-09-27T23:59:59.000Z

140

Core Holes | Open Energy Information  

Open Energy Info (EERE)

Core Holes Core Holes Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Core Holes Details Activities (8) Areas (7) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Exploration Drilling Parent Exploration Technique: Exploration Drilling Information Provided by Technique Lithology: Core holes are drilled to identify lithology and mineralization Stratigraphic/Structural: Retrieved samples can be used to identify fracture networks or faults Hydrological: Thermal: Thermal conductivity measurements can be done on retrieved samples. Dictionary.png Core Holes: A core hole is a well that is drilled using a hallow drill bit coated with synthetic diamonds for the purposes of extracting whole rock samples from

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Optimization of synchronization in gradient clustered networks  

E-Print Network [OSTI]

We consider complex clustered networks with a gradient structure, where sizes of the clusters are distributed unevenly. Such networks describe more closely actual networks in biophysical systems and in technological applications than previous models. Theoretical analysis predicts that the network synchronizability can be optimized by the strength of the gradient field but only when the gradient field points from large to small clusters. A remarkable finding is that, if the gradient field is sufficiently strong, synchronizability of the network is mainly determined by the properties of the subnetworks in the two largest clusters. These results are verified by numerical eigenvalue analysis and by direct simulation of synchronization dynamics on coupled-oscillator networks.

Xingang Wang; Liang Huang; Ying-Cheng Lai; Choy Heng Lai

2007-11-23T23:59:59.000Z

142

Optimization Online - An Accelerated Proximal Coordinate Gradient ...  

E-Print Network [OSTI]

Jul 7, 2014 ... An Accelerated Proximal Coordinate Gradient Method and its Application to Regularized Empirical Risk Minimization. Qihang Lin(qihang-lin...

Qihang Lin

2014-07-07T23:59:59.000Z

143

Probing black holes with constellation-X  

Science Journals Connector (OSTI)

Constellation-X is a premiere X-ray spectroscopy mission due to launch within the next decade. With a factor of 100 increase in sensitivity over current X-ray spectroscopy missions and an excellent energy resolution of 2 eV at 6 keV one of the prime science goals of the mission will be to observe activity near the black hole event horizon by measuring changes in the Fe K? fluorescence emission line profile and time-linked intensity changes between the line and the continuum. Detailed variability studies with Constellation-X will allow us to reconstruct images of the accretion disk probe the effects of strong gravity in the vicinity of black holes and measure black hole mass and spin via deconvolution of the line profile.

Kimberly A. Weaver

2001-01-01T23:59:59.000Z

144

Extremal limits and black hole entropy  

E-Print Network [OSTI]

Taking the extremal limit of a non-extremal Reissner-Nordstr\\"om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting fate -- while this region is absent in the extremal case, it does not disappear in the extremal limit but rather approaches a patch of $AdS_2\\times S^2$. In other words, the approach to extremality is not continuous, as the non-extremal Reissner-Nordstr\\"om solution splits into two spacetimes at extremality: an extremal black hole and a disconnected $AdS$ space. We suggest that the unusual nature of this limit may help in understanding the entropy of extremal black holes.

Sean M. Carroll; Matthew C. Johnson; Lisa Randall

2009-01-08T23:59:59.000Z

145

Black holes at accelerators.  

E-Print Network [OSTI]

ar X iv :h ep -p h/ 05 11 12 8v 3 6 A pr 2 00 6 Black Holes at Accelerators Bryan Webber Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK In theories with large extra dimensions and TeV-scale gravity, black holes... 2000 3000 Missing ET (GeV) Ar bi tra ry S ca le p p ? QCD SUSY 5 TeV BH (n=6) 5 TeV BH (n=2) (PT > 600 GeV) (SUGRA point 5) Figure 10: Missing transverse energy for various processes at the LHC. 4.2. Event Characteristics Turning from single...

Webber, Bryan R

146

Applying multiwell normalization in open hole log analysis  

E-Print Network [OSTI]

A major problem when analyzing open hole well logging data in large fields is the fact that the logs were run using different logging service companies, using different logging tools over a long time span. To obtain correct log interpretations...

Sinanan, Haydn Brent

2012-06-07T23:59:59.000Z

147

Microinstabilities in weak density gradient tokamak systems  

SciTech Connect (OSTI)

A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

Tang, W.M.; Rewoldt, G.; Chen, L.

1986-04-01T23:59:59.000Z

148

Chapter 5 Salinity Gradient Energy  

Science Journals Connector (OSTI)

There exists a huge potential for the generation of energy from the mixing of saltwater and freshwater. The potential is 2.6TW, which is more than the global electricity consumption (2.0TW). Two membrane-based technologies exist to convert this potentially available energy into useful power: pressure-retarded osmosis (PRO) and reverse electrodialysis (RED). In PRO, water is transported through a semipermeable membrane from the less concentrated solution toward the concentrated salt solution to generate power. In RED, salt ions are transported from the concentrated salt solution through ion exchange membranes toward the less concentrated solution to extract the energy. Both technologies were developed in the 1970s and 1980s and both regained interest lately due to recent developments in membrane technology and the need for sustainable energy processes. This chapter describes the potential of salinity gradient energy of both processes in detail, and an overview of the relevant literature on both technologies is presented. Furthermore, it summarizes the recent developments, pilot testing, scale-up, and future expectations of both technologies.

Kitty Nijmeijer; Sybrand Metz

2010-01-01T23:59:59.000Z

149

Inside a black hole  

Science Journals Connector (OSTI)

... interior. These models reveal several significantly different behaviours. The simplest model, of a 'Schwarzschild' black hole, which possesses mass but no charge or angular momentum, has an ... into account, seal off the 'tunnel', and yield an interior similar to the Schwarzschild model, with an all-encompassing crushing singularity. More recently, there have been attempts6- ...

William A. Hiscock

1991-10-24T23:59:59.000Z

150

Laser bottom hole assembly  

DOE Patents [OSTI]

There is provided for laser bottom hole assembly for providing a high power laser beam having greater than 5 kW of power for a laser mechanical drilling process to advance a borehole. This assembly utilizes a reverse Moineau motor type power section and provides a self-regulating system that addresses fluid flows relating to motive force, cooling and removal of cuttings.

Underwood, Lance D; Norton, Ryan J; McKay, Ryan P; Mesnard, David R; Fraze, Jason D; Zediker, Mark S; Faircloth, Brian O

2014-01-14T23:59:59.000Z

151

Were Archaean continental geothermal gradients much steeper than today? (reply)  

Science Journals Connector (OSTI)

... -We did not intend to suggest that our gradients bore any relationship to near-surface geothermal gradients. It may have been clearer to have termed them average ... gradients. It may have been clearer to have termed them average geothermal gradients. Our purpose in quoting these gradients was simply to emphasise that the temperature ...

KEVIN BURKE; W. S. F. KIDD

1978-08-17T23:59:59.000Z

152

Conformal Symmetry of a Black Hole as a Scaling Limit: A Black Hole in an Asymptotically Conical Box  

E-Print Network [OSTI]

We show that the previously obtained subtracted geometry of four-dimensional asymptotically flat multi-charged rotating black holes, whose massless wave equation exhibit $SL(2,\\R) \\times SL(2,\\R) \\times SO(3)$ symmetry may be obtained by a suitable scaling limit of certain asymptotically flat multi-charged rotating black holes, which is reminiscent of near-extreme black holes in the dilute gas approximation. The co-homogeneity-two geometry is supported by a dilation field and two (electric) gauge-field strengths. We also point out that these subtracted geometries can be obtained as a particular Harrison transformation of the original black holes. Furthermore the subtracted metrics are asymptotically conical (AC), like global monopoles, thus describing "a black hole in an AC box". Finally we account for the the emergence of the $SL(2,\\R) \\times SL(2,\\R) \\times SO(3)$ symmetry as a consequence of the subtracted metrics being Kaluza-Klein type quotients of $ AdS_3\\times 4 S^3$. We demonstrate that similar properties hold for five-dimensional black holes.

M. Cvetic; G. W. Gibbons

2012-01-03T23:59:59.000Z

153

Supermassive Black Holes  

E-Print Network [OSTI]

Supermassive black holes have generally been recognized as the most destructive force in nature. But in recent years, they have undergone a dramatic shift in paradigm. These objects may have been critical to the formation of structure in the early universe, spawning bursts of star formation and nucleating proto-galactic condensations. Possibly half of all the radiation produced after the Big Bang may be attributed to them, whose number is now known to exceed 300 million. The most accessible among them is situated at the Center of Our Galaxy. In the following pages, we will examine the evidence that has brought us to this point, and we will understand why many expect to actually image the event horizon of the Galaxy's central black hole within this decade.

Fulvio Melia

2007-05-10T23:59:59.000Z

154

Ballistic dispersion in temperature gradient focusing  

E-Print Network [OSTI]

regime is the most familiar regime in microfluidic systems, an oft-overlooked regime is that of purely kinematic (or ballistic) dispersion. In most microfluidic systems, this dispersion regime is transient systems. Keywords: microfluidics; temperature gradient focusing; kinematic dispersion; Taylor

Santiago, Juan G.

155

Separation of carbon nanotubes in density gradients  

DOE Patents [OSTI]

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2012-02-07T23:59:59.000Z

156

Separation of carbon nanotubes in density gradients  

DOE Patents [OSTI]

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2010-02-16T23:59:59.000Z

157

The proximal-proximal gradient algorithm  

E-Print Network [OSTI]

Aug 23, 2013 ... to consider a proximal gradient algorithm [11] for solving (1), where one ...... Hence, in the case when ? = 1 and M is surjective so that T = MR for...

2013-08-24T23:59:59.000Z

158

Program predicts two-phase pressure gradients  

SciTech Connect (OSTI)

The calculator program discussed, ORK, was designed for the HP-41CV hand-held calculator and uses the Orkiszewski correlation for predicting 2-phase pressure gradients in vertical tubulars. Accurate predictions of pressure gradients in flowing and gas lift wells over a wide range of well conditions can be obtained with this method, which was developed based on data from 148 wells. The correlation is one of the best generalized 2-phase pressure gradient prediction methods developed to date for vertical flow. It is unique in that hold-up is derived from observed physical phenomena, and the pressure gradient is related to the geometrical distribution of the liquid and gas phase (flow regime).

Jacks, D.C.; Hill, A.D.

1983-11-18T23:59:59.000Z

159

Temperatures, heat flow, and water chemistry from drill holes in the Raft  

Open Energy Info (EERE)

Temperatures, heat flow, and water chemistry from drill holes in the Raft Temperatures, heat flow, and water chemistry from drill holes in the Raft River geothermal system, Cassia County, Idaho Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Temperatures, heat flow, and water chemistry from drill holes in the Raft River geothermal system, Cassia County, Idaho Details Activities (1) Areas (1) Regions (0) Abstract: The Raft River area of Idaho contains a geothermal system of intermediate temperatures (approx. = 150 0C) at depths of about 1.5 km. Outside of the geothermal area, temperature measurements in three intermediate-depth drill holes (200 to 400 m) and one deep well (1500 m) indicate that the regional conductive heat flow is about 2.5 mucal/cm 2 sec or slightly higher and that temperature gradients range from 50 0 to 60

160

Slim Holes At Alvord Hot Springs Area (Combs, Et Al., 1999) | Open Energy  

Open Energy Info (EERE)

Combs, Et Al., 1999) Combs, Et Al., 1999) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Slim Holes At Alvord Hot Springs Area (Combs, Et Al., 1999) Exploration Activity Details Location Alvord Hot Springs Area Exploration Technique Slim Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes Anadarko Petroleum Corporation drilled two slimhole discoveries in the 1980s, one at Salt Wells, NV, and the other at Pueblo Valley, OR. Both of these slimholes were hot enough to discharge unassisted and were successfully flow tested. A slimhole at Pueblo Valley, in south-east Oregon was planned and permitted as a test well to evaluate an interval of fractured basalt which had been discovered while drilling an earlier thermal-gradient hole. Using a UDR1500 rig, the hole was rotary-drilled to

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Electromagnetic wave scattering by Schwarzschild black holes  

E-Print Network [OSTI]

We analyze the scattering of a planar monochromatic electromagnetic wave incident upon a Schwarzschild black hole. We obtain accurate numerical results from the partial wave method for the electromagnetic scattering cross section, and show that they are in excellent agreement with analytical approximations. The scattering of electromagnetic waves is compared with the scattering of scalar, spinor and gravitational waves. We present a unified picture of the scattering of all massless fields for the first time.

Lus C. B. Crispino; Sam R. Dolan; Ednilton S. Oliveira

2009-05-20T23:59:59.000Z

162

Light Loop Echoes and Blinking Black Holes  

E-Print Network [OSTI]

Radiation emitted near a black hole reaches the observer by multiple paths; and when this radiation varies in time, the time-delays between the various paths generate a "blinking" effect in the observed light curve L(t) or its auto-correlation function xi(T)= . For the particularly important "face-on" configuration (in which the hole is viewed roughly along its spin axis, while the emission comes roughly from its equatorial plane -- e.g. from the inner edge of its accretion disk, or from the violent flash of a nearby/infalling star) we calculate the blinking in detail by computing the time delay Delta t_{j}(r,a) and magnification mu_{j}(r,a) of the jth path (j=1,2,3,...), relative to the primary path (j=0), as a function of the emission radius r and black hole spin 0

163

Acoustic white holes in flowing atomic Bose-Einstein condensates  

E-Print Network [OSTI]

We study acoustic white holes in a steadily flowing atomic Bose-Einstein condensate. A white hole configuration is obtained when the flow velocity goes from a super-sonic value in the upstream region to a sub-sonic one in the downstream region. The scattering of phonon wavepackets on a white hole horizon is numerically studied in terms of the Gross-Pitaevskii equation of mean-field theory: dynamical stability of the acoustic white hole is found, as well as a signature of a nonlinear back-action of the incident phonon wavepacket onto the horizon. The correlation pattern of density fluctuations is numerically studied by means of the truncated-Wigner method which includes quantum fluctuations. Signatures of the white hole radiation of correlated phonon pairs by the horizon are characterized; analogies and differences with Hawking radiation from acoustic black holes are discussed. In particular, a short wavelength feature is identified in the density correlation function, whose amplitude steadily grows in time since the formation of the horizon. The numerical observations are quantitatively interpreted by means of an analytical Bogoliubov theory of quantum fluctuations for a white hole configuration within the step-like horizon approximation.

Carlos Mayoral; Alessio Recati; Alessandro Fabbri; Renaud Parentani; Roberto Balbinot; Iacopo Carusotto

2010-09-30T23:59:59.000Z

164

Black Holes And Their Entropy  

E-Print Network [OSTI]

This dissertation covers two di erent but related topics: the construction of new black hole solutions and the study of the microscopic origin of black hole entropy. In the solution part, two di erent sets of new solutions are found. The rst...

Mei, Jianwei

2010-10-12T23:59:59.000Z

165

Black Hole Energy Extraction Problems  

Science Journals Connector (OSTI)

... non-rotating black hole the particle can be lowered to no closer than 1.14 Schwarzschild radii, and the energy extracted can be no more than 63.2 per cent ... gram of matter-and the rope could be lowered no closer than 5 x 1011 Schwarzschild radii. This seems to rule out black holes as practical sources of energy. ...

1972-11-24T23:59:59.000Z

166

Optical black holes and solitons  

E-Print Network [OSTI]

We exhibit a static, cylindrically symmetric, exact solution to the Euler-Heisenberg field equations (EHFE) and prove that its effective geometry contains (optical) black holes. It is conjectured that there are also soliton solutions to the EHFE which contain black hole geometries.

Shawn Westmoreland

2010-12-21T23:59:59.000Z

167

Entropy of Lovelock Black Holes  

E-Print Network [OSTI]

A general formula for the entropy of stationary black holes in Lovelock gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.

Ted Jacobson; Robert C. Myers

1993-05-06T23:59:59.000Z

168

High-pressure liquid chromatographic gradient mixer  

DOE Patents [OSTI]

A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

Daughton, C.G.; Sakaji, R.H.

1982-09-08T23:59:59.000Z

169

String-Corrected Black Holes  

SciTech Connect (OSTI)

We investigate the geometry of four dimensional black hole solutions in the presence of stringy higher curvature corrections to the low energy effective action. For certain supersymmetric two charge black holes these corrections drastically alter the causal structure of the solution, converting seemingly pathological null singularities into timelike singularities hidden behind a finite area horizon. We establish, analytically and numerically, that the string-corrected two-charge black hole metric has the same Penrose diagram as the extremal four-charge black hole. The higher derivative terms lead to another dramatic effect -- the gravitational force exerted by a black hole on an inertial observer is no longer purely attractive! The magnitude of this effect is related to the size of the compactification manifold.

Hubeny, Veronika; Maloney, Alexander; Rangamani, Mukund

2005-02-07T23:59:59.000Z

170

Photopolymerization in Microfluidic Gradient Generators: Microscale  

E-Print Network [OSTI]

-compliance profiles that are tunable on the micro- scale. The most straightforward way to create substrates with vari through the development of microfluidic networks,[7,8] with which one can easily generate solution (e microscale gradients with microfluidic networks, and a recent study that demon- strated

171

Porting the NAS-NPB Conjugate Gradient  

E-Print Network [OSTI]

Porting the NAS-NPB Conjugate Gradient Benchmark to CUDA NVIDIA Corporation #12;Outline ! Overview of CG benchmark ! Overview of CUDA Libraries ! CUSPARSE ! CUBLAS ! Porting Sequence ! Algorithm Analysis ! Data/Code Analysis This porting approach uses CUDA Libraries exclusively. (We will not write

Crawford, T. Daniel

172

Joining of Tungsten Armor Using Functional Gradients  

SciTech Connect (OSTI)

The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

John Scott O'Dell

2006-12-31T23:59:59.000Z

173

Salinity gradient energy potential in Colombia considering site specific constraints  

Science Journals Connector (OSTI)

Abstract The theoretical potential of salinity gradient energy in river mouth systems is the maximum amount of energy that can be extracted from the controlled mixing of river water and seawater. It is calculated using the Gibbs free energy of mixing equations considering as inputs the mean rivers' discharge and the long term salinity of the ocean basin. However, this theoretical amount of energy can be far from the reality because both, the river discharge and the salinity of the ocean, have natural variations in different time scales. In this paper we expose the site constraints related with the variability of the salinity gradients that must be considered in order to make a more accurate estimation of the available resources and calculate the so-called site specific potential for the most important and feasible river mouths of Colombia. The results show that in Colombia a mean site specific potential of 15.6GW can be achieved, mainly in the Magdalena River mouth (97% of total). But more important, the results show that the salinity structure of the studied systems have different responses to variations of the environmental forcing, despite being located in the same ocean basin, and therefore, the energy potential for each river mouth has different variability patterns at different time scales. Decreases of the estimated energy potential up to 69% were found when the site specific potential is calculated instead of the theoretical potential. This prove that more detailed input data than long term discharges and salinities are necessary in order to make accurate estimations of local and regional salinity gradient energy potentials.

Oscar Alvarez-Silva; Andrs F. Osorio

2015-01-01T23:59:59.000Z

174

The structure of black hole magnetospheres I. Schwarzschild black holes  

Science Journals Connector (OSTI)

......2000 RAS, MNRAS 315, 89 97 force-free black hole magnetosphere...However, there is nothing fundamental about the paraboloidal shape...in stationary axisymmetric force-free magnetospheres. Therefore...Stegun I. A., 1972, Handbook of Mathematical Functions......

Pranab Ghosh

2000-06-11T23:59:59.000Z

175

Black Holes in Active Galaxies  

E-Print Network [OSTI]

Recent years have seen tremendous progress in the quest to detect supermassive black holes in the centers of nearby galaxies, and gas-dynamical measurements of the central masses of active galaxies have been valuable contributions to the local black hole census. This review summarizes measurement techniques and results from observations of spatially resolved gas disks in active galaxies, and reverberation mapping of the broad-line regions of Seyfert galaxies and quasars. Future prospects for the study of black hole masses in active galaxies, both locally and at high redshift, are discussed.

A. J. Barth

2003-10-15T23:59:59.000Z

176

Non-linear Plasma Wake Growth of Electron Holes  

E-Print Network [OSTI]

An object's wake in a plasma with small Debye length that drifts \\emph{across} the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind wake and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable...

Hutchinson, I H; Zhou, C

2015-01-01T23:59:59.000Z

177

Non-preconditioned conjugate gradient on cell and FPCA-based hybrid supercomputer nodes  

SciTech Connect (OSTI)

This work presents a detailed implementation of a double precision, Non-Preconditioned, Conjugate Gradient algorithm on a Roadrunner heterogeneous supercomputer node. These nodes utilize the Cell Broadband Engine Architecture{trademark} in conjunction with x86 Opteron{trademark} processors from AMD. We implement a common Conjugate Gradient algorithm, on a variety of systems, to compare and contrast performance. Implementation results are presented for the Roadrunner hybrid supercomputer, SRC Computers, Inc. MAPStation SRC-6 FPGA enhanced hybrid supercomputer, and AMD Opteron only. In all hybrid implementations wall clock time is measured, including all transfer overhead and compute timings.

Dubois, David H [Los Alamos National Laboratory; Dubois, Andrew J [Los Alamos National Laboratory; Boorman, Thomas M [Los Alamos National Laboratory; Connor, Carolyn M [Los Alamos National Laboratory

2009-03-10T23:59:59.000Z

178

Space X-ray Solves Mysteries of Black Holes | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

Space X-ray Solves Mysteries of Black Holes Space X-ray Solves Mysteries of Black Holes Space X-ray Solves Mysteries of Black Holes March 13, 2013 - 3:57pm Addthis Space X-ray Solves Mysteries of Black Holes Anne M. Stark Senior Public Information Officer, Lawrence Livermore National Laboratory "We know that black holes have a strong link to their host galaxy." Astrophysicist Bill Craig, a member of the LLNL team An international team including Lawrence Livermore National Laboratory scientists has definitively measured the spin rate of a supermassive black hole for the first time. The findings, made by the two X-ray space observatories, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's XMM-Newton, solve a long-standing debate about similar measurements in

179

Double Core-Hole Production in N{sub 2}: Beating the Auger Clock  

SciTech Connect (OSTI)

We investigate the creation of double K-shell holes in N{sub 2} molecules via sequential absorption of two photons on a time scale shorter than the core-hole lifetime by using intense x-ray pulses from the Linac Coherent Light Source free electron laser. The production and decay of these states is characterized by photoelectron spectroscopy and Auger electron spectroscopy. In molecules, two types of double core holes are expected, the first with two core holes on the same N atom, and the second with one core hole on each N atom. We report the first direct observations of the former type of core hole in a molecule, in good agreement with theory, and provide an experimental upper bound for the relative contribution of the latter type.

Fang, L.; Berrah, N. [Physics Department, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Hoener, M. [Physics Department, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Gessner, O.; Kornilov, O. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Tarantelli, F. [Dipartimento di Chimica, Universitadi Perugia, and ISTM-CNR, 06123 Perugia (Italy); Pratt, S. T.; Kanter, E. P. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Buth, C. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Guehr, M.; Bucksbaum, P. H.; Cryan, J.; Glownia, M. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Bostedt, C.; Bozek, J. D.; Coffee, R. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Chen, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kukk, E. [Department of Physics and Astronomy, University of Turku 20014 Turku (Finland); Leone, S. R. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Departments of Chemistry and Physics, University of California Berkeley, California 94710 (United States)

2010-08-20T23:59:59.000Z

180

Double core hole production in N{sub 2} : beating the auger clock.  

SciTech Connect (OSTI)

We investigate the creation of double K-shell holes in N{sub 2} molecules via sequential absorption of two photons on a time scale shorter than the core-hole lifetime by using intense x-ray pulses from the Linac Coherent Light Source free electron laser. The production and decay of these states is characterized by photoelectron spectroscopy and Auger electron spectroscopy. In molecules, two types of double core holes are expected, the first with two core holes on the same N atom, and the second with one core hole on each N atom. We report the first direct observations of the former type of core hole in a molecule, in good agreement with theory, and provide an experimental upper bound for the relative contribution of the latter type.

Fang, L.; Hoener, M.; Gessner, O.; Tarantelli, F.; Pratt, S. T.; Kornilov, O.; Buth, C.; Guhr, M.; Kanter, E. P.; Bostedt, C.; Bozek, J. D.; Bucksbaum, P. H.; Chen, M.; Coffee, R.; Cryan, J.; Glownia, J. M.; Kukk, E.; Leone, S. R.; Berrah, N. (Chemical Sciences and Engineering Division); ( XSD); (Western Michigan Univ.); (LBNL); (Univ. di Perugia); (Louisiana State Univ.); (SLAC National Accelerator Lab.); (LLNL); (Univ. of Turku); (Univ. of California at Berkeley)

2010-01-01T23:59:59.000Z

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181

Life in a Tree Hole  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Tree Hole Tree Hole Nature Bulletin No. 581 November 21, 1959 Forest Preserve District of Cook County Daniel Ryan, President Roberts Mann, Conservation Editor David H Thompson, Senior Naturalist LIFE IN A TREE HOLE A forest is much more than just trees. It includes all of the underbrush, wildflowers and other vegetation that grow beneath these trees; as well as all of its animal life, both large and small. Sunshine, rain, wind, soil, and the leaf litter on the ground are part of it, too. A forest is a community -- a fabric in which the lives of its inhabitants are woven together and into their surroundings by a complex web of interrelations. Tree holes -- together with the birds, mammals and small life which they shelter -- furnish an important binding force in this forest community.

182

Thermodynamics of regular black hole  

E-Print Network [OSTI]

We investigate thermodynamics for a magnetically charged regular black hole (MCRBH), which comes from the action of general relativity and nonlinear electromagnetics, comparing with the Reissner-Norstr\\"om (RN) black hole in both four and two dimensions after dimensional reduction. We find that there is no thermodynamic difference between the regular and RN black holes for a fixed charge $Q$ in both dimensions. This means that the condition for either singularity or regularity at the origin of coordinate does not affect the thermodynamics of black hole. Furthermore, we describe the near-horizon AdS$_2$ thermodynamics of the MCRBH with the connection of the Jackiw-Teitelboim theory. We also identify the near-horizon entropy as the statistical entropy by using the AdS$_2$/CFT$_1$ correspondence.

Yun Soo Myung; Yong-Wan Kim; Young-Jai Park

2007-08-23T23:59:59.000Z

183

Of the Black Hole Thermodynamics  

E-Print Network [OSTI]

About thirty years ago, Bekenstein and Hawking introduced three basic concepts relating to black hole, namely, the "area entropy", "gravitation temperature" and "thermal radiation". The author analyzes these concepts systematically and concludes that they are mostly inadequate or wrong. He points out that a black hole's taking in thermal radiation from the space is an energy-gathering process. It is special, even extraordinary. It reduces entropy, violating Clausius' second law.

Xinyong Fu

2005-01-11T23:59:59.000Z

184

MEASUREMENTS OF ANISOTROPIC ION TEMPERATURES, NON-THERMAL VELOCITIES, AND DOPPLER SHIFTS IN A CORONAL HOLE  

SciTech Connect (OSTI)

We present a new diagnostic allowing one to measure the anisotropy of ion temperatures and non-thermal velocities, as well as Doppler shifts with respect to the ambient magnetic field. This method provides new results, as well as an independent test for previous measurements obtained with other techniques. Our spectral data come from observations of a low-latitude, on-disk coronal hole. A potential field source surface model was used to calculate the angle between the magnetic field lines and the line of sight for each spatial bin of the observation. A fit was performed to determine the line widths and Doppler shifts parallel and perpendicular to the magnetic field. For each line width component we derived ion temperatures T {sub i,} and T {sub i, Parallel-To} and non-thermal velocities v {sub nt,} and v {sub nt, Parallel-To }. T {sub i,} was cooler than off-limb polar coronal hole measurements, suggesting increasing collisional cooling with decreasing height. T {sub i, Parallel-To} is consistent with a uniform temperature of (1.8 {+-} 0.2) Multiplication-Sign 10{sup 6} K for each ion. Since parallel ion heating is expected to be weak, this ion temperature should reflect the proton temperature. A comparison between our results and others implies a large proton temperature gradient around 1.02 R {sub Sun }. The non-thermal velocities are thought to be proportional to the amplitudes of various waves. Our results for v {sub nt,} agree with Alfven wave amplitudes inferred from off-limb polar coronal hole line width measurements. Our v {sub nt, Parallel-To} results are consistent with slow magnetosonic wave amplitudes inferred from Fourier analysis of time-varying intensity fluctuations. Doppler shift measurements yield outflows of Almost-Equal-To 5 km s{sup -1} for ions formed over a broad temperature range. This differs from other studies that found a strong Doppler shift dependence on formation temperature.

Hahn, M.; Savin, D. W. [Columbia Astrophysics Laboratory, Columbia University, MC 5247, 550 West 120th Street, New York, NY 10027 (United States)] [Columbia Astrophysics Laboratory, Columbia University, MC 5247, 550 West 120th Street, New York, NY 10027 (United States)

2013-02-15T23:59:59.000Z

185

Electron profile stiffness and critical gradient studies  

SciTech Connect (OSTI)

Electron profile stiffness was studied in DIII-D L-mode discharges by systematically varying the heat flux in a narrow region with electron cyclotron heating and measuring the local change produced in {nabla}T{sub e}. Electron stiffness was found to slowly increase with toroidal rotation velocity. A critical inverse temperature gradient scale length 1/L{sub C} {approx} 3 m{sup -1} was identified at {rho}=0.6 and found to be independent of rotation. Both the heat pulse diffusivity and the power balance diffusivity, the latter determined by integrating the measured dependence of the heat pulse diffusivity on -{nabla}T{sub e}, were fit reasonably well by a model containing a critical inverse temperature gradient scale length and varying linearly with 1/L{sub T} above the threshold.

DeBoo, J. C.; Petty, C. C.; Burrell, K. H.; Smith, S. P. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); White, A. E. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Doyle, E. J.; Hillesheim, J. C.; Rhodes, T. L.; Schmitz, L.; Wang, G.; Zeng, L. [University of California-Los Angeles, Los Angeles, California 90095-7099 (United States); Holland, C. [University of California-San Diego, La Jolla, California 92093-0417 (United States); McKee, G. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-08-15T23:59:59.000Z

186

Automated apparatus for producing gradient gels  

DOE Patents [OSTI]

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

Anderson, Norman L. (Clarendon Hills, IL)

1986-01-01T23:59:59.000Z

187

The Argonne Zero Gradient Synchrotron (ZGS)  

Science Journals Connector (OSTI)

A 12.5 billion electron volt (BeV) particle accelerator the Zero Gradient Synchrotron was constructed and put into operation at the Argonne National Laboratory in August 1963. The ZGS will form the center for high energy physics research in the Midwestern part of this country. In this paper a brief description of the ZGS is given together with a discussion of the aims methods and equipment of experimental high energy physics research.

L. C. Teng

1964-01-01T23:59:59.000Z

188

The Boussinesq Problem in Dipolar Gradient Elasticity  

E-Print Network [OSTI]

The three-dimensional axisymmetric Boussinesq problem of an isotropic half-space subjected to a concentrated normal quasi-static load is studied within the framework of linear dipolar gradient elasticity. Our main concern is to determine possible deviations from the predictions of classical linear elastostatics when a more refined theory is employed to attack the problem. Of special importance is the behavior of the new solution near to the point of application of the load where pathological singularities exist in the classical solution. The use of the theory of gradient elasticity is intended here to model the response of materials with microstructure in a manner that the classical theory cannot afford. A linear version of this theory results by considering a linear isotropic expression for the strain-energy density that depends on strain-gradient terms, in addition to the standard strain terms appearing in classical elasticity. Through this formulation, a microstructural material constant is introduced, in addition to the standard Lam\\'e constants. The solution method is based on integral transforms and is exact. The present results show significant departure from the predictions of classical elasticity. Indeed, continuous and bounded displacements are predicted at the points of application of the concentrated load. Such a behavior of the displacement field is, of course, more natural than the singular behavior exhibited in the classical solution.

H. G. Georgiadis; P. A. Gourgiotis; D. S. Anagnostou

2014-03-31T23:59:59.000Z

189

Gradient-based Methods for Production Optimization of Oil Reservoirs  

E-Print Network [OSTI]

Gradient-based Methods for Production Optimization of Oil Reservoirs Eka Suwartadi Doctoral Thesis oil reservoirs. Gradient- based optimization, which utilizes adjoint-based gradient computation optimization for water flooding in the secondary phase of oil recovery is the main topic in this thesis

Foss, Bjarne A.

190

NEW RADIAL ABUNDANCE GRADIENTS FOR NGC 628 AND NGC 2403  

SciTech Connect (OSTI)

Motivated by recent interstellar medium studies, we present high quality MMT and Gemini spectroscopic observations of H II regions in the nearby spiral galaxies NGC 628 and NGC 2403 in order to measure their chemical abundance gradients. Using long-slit and multi-object mask optical spectroscopy, we obtained measurements of the temperature sensitive auroral lines [O III] ?4363 and/or [N II] ?5755 at a strength of 4? or greater in 11 H II regions in NGC 628 and 7 regions in NGC 2403. These observations allow us, for the first time, to derive an oxygen abundance gradient in NGC 628 based solely on 'direct' oxygen abundances of H II regions: 12 + log(O/H) = (8.43 0.03) + (0.017 0.002) R{sub g} (dex kpc{sup 1}), with a dispersion in log(O/H) of ? = 0.10 dex, from 14 regions with a radial coverage of ?2-19 kpc. This is a significantly shallower slope than found by previous 'strong-line' abundance studies. In NGC 2403, we derive an oxygen abundance gradient of 12 + log(O/H) = (8.48 0.04) + (0.032 0.007) R{sub g} (dex kpc{sup 1}), with a dispersion in log(O/H) of ? = 0.07 dex, from seven H II with a radial coverage of ?1-10 kpc. Additionally, we measure the N, S, Ne, and Ar abundances. We find the N/O ratio decreases with increasing radius for the inner disk, but reaches a plateau past R{sub 25} in NGC 628. NGC 2403 also has a negative N/O gradient with radius, but we do not sample the outer disk of the galaxy past R{sub 25} and so do not see evidence for a plateau. This bi-modal pattern measured for NGC 628 indicates dominant contributions from secondary nitrogen inside of the R{sub 25} transition and dominantly primary nitrogen farther out. As expected for ?-process elements, S/O, Ne/O, and Ar/O are consistent with constant values over a range in oxygen abundance.

Berg, Danielle A.; Skillman, Evan D. [Department of Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); Croxall, Kevin V. [Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Marble, Andrew R. [National Solar Observatory, 950 N Cherry Avenue, Tucson, AZ 85719 (United States); Smith, J. D. [Ritter Astrophysical Observatory, University of Toledo, Toledo, OH 43606 (United States); Gordon, Karl [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Kennicutt, Robert C. Jr. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Garnett, Donald R., E-mail: berg@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: croxall.5@osu.edu, E-mail: amarble@nso.edu, E-mail: jd.smith@utoledo.edu, E-mail: kgordon@stsci.edu, E-mail: robk@ast.cam.ac.uk

2013-10-01T23:59:59.000Z

191

Weak field limit of Reissner-Nordstrm black hole lensing  

Science Journals Connector (OSTI)

We study gravitational lensing by a Reissner-Nordstrm black hole in the weak field limit. We obtain the basic equations for the deflection angle and time delay and find analytical expressions for the positions and amplifications of the primary and secondary images. Because of a net positive charge, the separation between images increases, but no change in the total magnification occurs.

Mauro Sereno

2004-01-13T23:59:59.000Z

192

Reissner-Nordstrom black hole in dark energy background  

E-Print Network [OSTI]

In this paper we propose a stationary solution of Einstein's field equations describing Reissner-Nordstrom black hole in dark energy background. It is to be regarded as the Reissner-Nordstrom black hole is embedded into the dark energy solution producing Reissner-Nordstrom-dark energy black hole. We find that the space-time geometry of Reissner-Nordstrom-dark energy solution is Petrov type $D$ in the classification of space-times. It is also shown that the embedded space-time possesses an energy-momentum tensor of the electromagnetic field interacting with the dark energy having negative pressure. We find the energy-momentum tensor for dark energy violates the the strong energy condition due to the negative pressure, whereas that of the electromagnetic field obeys the strong energy condition. It is shown that the time-like vector field for an observer in the Reissner-Nordstrom-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity of the horizons for the embedded dark energy black hole. The characteristic properties of relativistic dark energy based on the de Sitter solution is discussed in an appendix.

Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh

2014-11-29T23:59:59.000Z

193

Black hole quantum tunnelling and black hole entropy correction  

E-Print Network [OSTI]

Parikh-Wilczek tunnelling framework, which treats Hawking radiation as a tunnelling process, is investigated again. As the first order correction, the log-corrected entropy-area relation naturally emerges in the tunnelling picture if we consider the emission of a spherical shell. The second order correction of the emission rate for the Schwarzschild black hole is calculated too. In this level, the result is still in agreement with the unitary theory, however, the entropy of the black hole will contain three parts: the usual Bekenstein-Hawking entropy, the logarithmic term and the inverse area term. In our results the coefficient of the logarithmic term is -1. Apart from a coefficient, Our correction to the black hole entropy is consistent with that of loop quantum gravity.

Jingyi Zhang

2008-06-15T23:59:59.000Z

194

Lepidium latifolium reproductive potential and seed dispersal along salinity and moisture gradients  

E-Print Network [OSTI]

Preserve where the salinity gradient was narrow. Conversely,production along the salinity gradient between the freshdispersal along salinity and moisture gradients Samuel P.

Leininger, Samuel P.; Foin, Theodore C.

2009-01-01T23:59:59.000Z

195

Hole in the ozone layer?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hole in the ozone layer? Hole in the ozone layer? Name: Kelley Location: N/A Country: N/A Date: N/A Question: Is there really a hole in the ozone layer? Replies: That depends on what one means by a "hole". There is a thinning of the layer that is particularly severe during certain seasons at the poles. But the ozone layer is thinning most everywhere. The thinning around the south pole of earth is particularly stunning, and has been referred to as a hole even though some ozone still exists there, it is much less concentrated. As you may know, this ozone destruction is probably due to human release of pollutants such as clorofluorocarbons (CFCs) an due to natural sources such as chemicals from volcanic eruptions. CFCs are used is cooling systems such as refrigerators and air conditioning. There is an international agreement to phase out the use of these destructive chemicals but they won't be banned entirely for years for fears of losing money. Meanwhile the ozone layer thins and we are exposed to increasingly higher doses of cancer causing radiation

196

Fuel Injector Holes  

Broader source: Energy.gov (indexed) [DOE]

cavitation damage in a benchtop rig Quantify change in mass (mass loss) and erosion rate of test coupon as a function of time - Impact of different alloy composition and...

197

Coherence effects in hole superconductivity  

Science Journals Connector (OSTI)

We discuss the behavior of various observables that depend on matrix elements of operators in the superconducting state within the model of hole superconductivity. In this model, the gap exhibits a linear dependence on the band energy, and the bandwidth depends on the carrier concentration and can become very small for low hole density. We study, in particular, the behavior of ultrasonic attenuation, NMR relaxation rate, and electromagnetic absorption, and present results for parameters expected to be in the range that describes the high-Tc oxides. It is found that the energy dependence of the gap does not give rise to qualitatively different behavior, but significant differences from weak-coupling BCS behavior occur at low hole concentration due to the extreme narrowness of the band.

F. Marsiglio and J. E. Hirsch

1991-12-01T23:59:59.000Z

198

The Schwarzschild black hole as a gravitational mirror  

Science Journals Connector (OSTI)

The gravitational field outside of a nonrotating black hole is described using the Schwarzschild metric. The geodesic equations of the Schwarzschild metric are derived and those describing null and circular timelike orbits are discussed. Some numerical solutions of the null geodesic equations are shown. These depict photon trajectories which circle the black hole one or two times and then terminate at their emission points. Thus a sequence of ring?shaped mirror images is produced. An equation which gives the angle between the photons trajectory and the radial direction at the emitter is derived and applied to the numerical solutions. These results serve to illustrate how an observer passes through his or her mirror image at r=3 MG/c 2 as he or she moves toward a Schwarzschild black hole.

W. M. Stuckey

1993-01-01T23:59:59.000Z

199

Stellar black holes and the origin of cosmic acceleration  

Science Journals Connector (OSTI)

The discovery of cosmic acceleration has presented a unique challenge for cosmologists. As observational cosmology forges ahead, theorists have struggled to make sense of a standard model that requires extreme fine-tuning. This challenge is known as the cosmological constant problem. The theory of gravitational aether is an alternative to general relativity that does not suffer from this fine-tuning problem, as it decouples the quantum field theory vacuum from geometry, while remaining consistent with other tests of gravity. In this paper, we study static black hole solutions in this theory and show that it manifests a UV-IR coupling: Aether couples the space-time metric close to the black hole horizon, to metric at infinity. We then show that using the trans-Planckian ansatz (as a quantum gravity effect) close to the black hole horizon, leads to an accelerating cosmological solution, far from the horizon. Interestingly, this acceleration matches current observations for stellar-mass black holes. Based on our current understanding of the black hole accretion history in the Universe, we then make a prediction for how the effective dark energy density should evolve with redshift, which can be tested with future dark energy probes.

Chanda Prescod-Weinstein; Niayesh Afshordi; Michael L. Balogh

2009-08-18T23:59:59.000Z

200

Black Hole Motion as Catalyst of Orbital Resonances  

E-Print Network [OSTI]

The motion of a black hole about the centre of gravity of its host galaxy induces a strong response from the surrounding stellar population. We treat the case of a harmonic potential analytically and show that half of the stars on circular orbits in that potential shift to an orbit of lower energy, while the other half receive a positive boost and recede to a larger radius. The black hole itself remains on an orbit of fixed amplitude and merely acts as a catalyst for the evolution of the stellar energy distribution function f(E). We show that this effect is operative out to a radius of approx 3 to 4 times the hole's influence radius, R_bh. We use numerical integration to explore more fully the response of a stellar distribution to black hole motion. We consider orbits in a logarithmic potential and compare the response of stars on circular orbits, to the situation of a `warm' and `hot' (isotropic) stellar velocity field. While features seen in density maps are now wiped out, the kinematic signature of black hole motion still imprints the stellar line-of-sight mean velocity to a magnitude ~18% the local root mean-square velocity dispersion sigma.

C. M. Boily; T. Padmanabhan; A. Paiement

2007-05-18T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Measuring the Black Hole Spin in Sgr A*  

E-Print Network [OSTI]

The polarized mm/sub-mm radiation from Sgr A* is apparently produced by a Keplerian structure whose peak emission occurs within several Schwarzschild radii (r_S=2GM/c^2) of the black hole. The Chandra X-ray counterpart, if confirmed, is presumably the self-Comptonized component from this region. In this paper, we suggest that sub-mm timing observations could yield a signal corresponding to the period P_0 of the marginally stable orbit, and therefore point directly to the black hole's spin a. Sgr A*'s mass is now known to be (2.6\\pm 0.2)\\times 10^6 M_\\odot (an unusually accurate value for supermassive black hole candidates), for which 2.7 minhole (a=0) should have P_0 ~ 20 min. The identification of the orbital frequency with the innermost stable circular orbit is made feasible by the transition from optically thick to thin emission at sub-mm wavelengths. With stratification in the emitter, the peak of the sub-mm bump in Sgr A*'s spectrum is thus produced at the smallest radius. We caution, however, that theoretical uncertainties in the structure of the emission region may still produce some ambiguity in the timing signal. Given that Sgr A*'s flux at $\

Fulvio Melia; Benjamin C. Bromley; Siming Liu; Christopher; K. Walker

2001-05-11T23:59:59.000Z

202

A scale-free analysis of magnetic holes in the solar wind  

E-Print Network [OSTI]

Magnetic holes are isolated intervals of depleted interplanetary magnetic field (IMF) strength on timescales of several seconds to several hours. These intervals have been seen as often as several times per day in the ...

Stevens, M. L. (Michael Louis)

2006-01-01T23:59:59.000Z

203

Lateral Current Density Distribution and Spatial Hole Burning in Quantum Cascade Lasers  

Science Journals Connector (OSTI)

We have investigated non-uniformity of the lateral current density and lateral hole burning in Quantum Cascaded lasers, e.g., the current density in the mode center is 1.8 times that...

Huang, Xue; Dikmelik, Yamac; Gmachl, Claire F

204

Acoustical power amplification and damping by temperature gradients  

Science Journals Connector (OSTI)

Ceperley proposed a concept of a traveling wave heat engine [A pistonless Stirling engineThe traveling wave heat engine J. Acoust. Soc. Am. 66 15081513 (1979).] that provided a starting point of thermoacoustics today. This paper verifies experimentally his idea through observation of amplification and strong damping of a plane acoustic traveling wave as it passes through axial temperature gradients. The acoustic power gain is shown to obey a universal curve specified by a dimensionless parameter ???; ? is the angular frequency and ?? is the relaxation time for the gas to thermally equilibrate with channel walls. As an application of his idea a three-stage acoustic power amplifier is developed which attains the gain up to 10 with a moderate temperature ratio of 2.3.

Tetsushi Biwa; Ryo Komatsu; Taichi Yazaki

2011-01-01T23:59:59.000Z

205

Black hole binary inspiral and trajectory dominance  

E-Print Network [OSTI]

Gravitational waves emitted during the inspiral, plunge and merger of a black hole binary carry linear momentum. This results in an astrophysically important recoil to the final merged black hole, a kick that can eject ...

Price, Richard H.

206

Black hole Meissner effect and entanglement  

E-Print Network [OSTI]

Extremal black holes tend to expel magnetic and electric fields. Fields are unable to reach the horizon because the length of the black hole throat blows up in the extremal limit. The length of the throat is related to the ...

Penna, Robert

207

Analysis of Bacterial Communities in Seagrass Bed Sediments by Double-Gradient Denaturing Gradient Gel Electrophoresis  

E-Print Network [OSTI]

Microbial Ecology Analysis of Bacterial Communities in Seagrass Bed Sediments by Double, including the presence or absence of vegetation, depth into sediment, and season. Double- gradient of these similarity coefficients were used to group banding patterns by depth into sediment, presence or absence

Sherman, Tim

208

Hawking Emission and Black Hole Thermodynamics  

E-Print Network [OSTI]

A brief review of Hawking radiation and black hole thermodynamics is given, based largely upon hep-th/0409024.

Don N. Page

2006-12-18T23:59:59.000Z

209

11/3/08 2:45 PMCASES WITHOUT BORDERS; At the Old Swimming Hole, a Vicious Cycle Thrives -New York Times Page 1 of 3http://query.nytimes.com/gst/fullpage.html?res=9F00EFDA1E3DF931A35752C1A9629C8B63&sec=&spon=&pagewanted=print  

E-Print Network [OSTI]

. MCNEIL JR. The pond was about the size of a school swimming pool, except it was surrounded by dry mud11/3/08 2:45 PMCASES WITHOUT BORDERS; At the Old Swimming Hole, a Vicious Cycle Thrives - New York=&spon=&pagewanted=print November 2, 2004 CASES WITHOUT BORDERS; At the Old Swimming Hole, a Vicious Cycle Thrives By DONALD G

Davis, Richard E.

210

High precision, rapid laser hole drilling  

DOE Patents [OSTI]

A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.

2013-04-02T23:59:59.000Z

211

Absorption cross section in Lifshitz black hole  

E-Print Network [OSTI]

We derive the absorption cross section of a minimally coupled scalar in the Lifshitz black hole obtained from the new massive gravity. The absorption cross section reduces to the horizon area in the low energy and massless limit of s-wave mode propagation, indicating that the Lifshitz black hole also satisfies the universality of low energy absorption cross section for black holes.

Taeyoon Moon; Yun Soo Myung

2012-05-10T23:59:59.000Z

212

Signatures of black holes at the LHC  

E-Print Network [OSTI]

Signatures of black hole events at CERN's Large Hadron Collider are discussed. Event simulations are carried out with the Fortran Monte Carlo generator CATFISH. Inelasticity effects, exact field emissivities, color and charge conservation, corrections to semiclassical black hole evaporation, gravitational energy loss at formation and possibility of a black hole remnant are included in the analysis.

Marco Cavaglia; Romulus Godang; Lucien M. Cremaldi; Donald J. Summers

2007-07-02T23:59:59.000Z

213

Gyrokinetic and Gyrofluid Models for Zonal Flow Dynamics in Ion and Electron Temperature Gradient Turbulence  

SciTech Connect (OSTI)

Collisionless time evolution of zonal flows in ion and electron temperature gradient turbulence in toroidal plasmas is investigated. The responses of the zonal-flow potential to the initial perturbation and to the turbulence source are determined from the gyrokinetic equations combined with the Poisson equation, A novel gyrofluid model is presented, which properly describes the zonal-flow time evolution and reproduces the same residual zonal-flow levels as predicted by the gyrokinetic model.

Sugama, H.; Watanabe, T.-H. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan); Graduate University for Advanced Studies, Toki, Gifu, 509-5292 (Japan); Ferrando i Margalet, S. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan)

2006-11-30T23:59:59.000Z

214

Spray atomization characteristics of a GDI injector equipped with a group-hole nozzle  

Science Journals Connector (OSTI)

Abstract The main purpose of this paper is to analyze the spray characteristics of a group-hole nozzle in terms of spray behavior and atomization process in comparison to the characteristics of a single-hole nozzle as reference. Spray visualization and PDPA (phase Doppler particle analyzer) experiments were performed using a GDI adjustable injector, which can adopt a different type of nozzle at free spray conditions. By analyzing the spray development behavior and distribution of droplet velocity and diameter based on a time series, and comparing these results with that of a single-hole nozzle, the effects of the group-hole nozzle on the spray characteristics in a GDI injection were elucidated. Experimental results showed that the development processes of spray behavior from a group-hole nozzle were similar to that of the single-hole nozzle. Both the sprays had similar spray tip penetration and dispersion at the same stages of development. However, owing to the constant spray momentum from a spray interaction, the spray behavior from the group-hole nozzle seemed to be more stable than that of the single-hole nozzle. In terms of the averaged droplet size, the group-hole nozzle held an advantage over the single-hole nozzle in decreasing Sauter mean diameter (SMD) by approximately 2?m. In addition, in comparison to the spatial distribution of droplet diameter and velocity between them, it can be confirmed that the group-hole nozzle has strong effects on reduction in diameter as well as rapid dispersion of droplet due to active air entrainment. These atomization characteristics are considered as an important advantages for improving mixture formation in GDI engine.

Sanghoon Lee; Sungwook Park

2014-01-01T23:59:59.000Z

215

Probing the puncture for black hole simulations  

SciTech Connect (OSTI)

With the puncture method for black hole simulations, the second infinity of a wormhole geometry is compactified to a single 'puncture point' on the computational grid. The region surrounding the puncture quickly evolves to a trumpet geometry. The computational grid covers only a portion of the trumpet throat. It ends at a boundary whose location depends on resolution. This raises the possibility that perturbations in the trumpet geometry could propagate down the trumpet throat, reflect from the puncture boundary, and return to the black hole exterior with a resolution-dependent time delay. Such pathological behavior is not observed. This is explained by the observation that some perturbative modes propagate in the conformal geometry, others propagate in the physical geometry. The puncture boundary exists only in the physical geometry. The modes that propagate in the physical geometry are always directed away from the computational domain at the puncture boundary. The finite difference stencils ensure that these modes are advected through the boundary with no coupling to the modes that propagate in the conformal geometry. These results are supported by numerical experiments with a code that evolves spherically symmetric gravitational fields with standard Cartesian finite difference stencils. The code uses the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein's equations with 1+log slicing and gamma-driver shift conditions.

Brown, J. David [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2009-10-15T23:59:59.000Z

216

Ultrafast Core-Hole Induced Dynamics in Water  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Ultrafast Core-Hole Induced Ultrafast Core-Hole Induced Dynamics in Water Ultrafast Core-Hole Induced Dynamics in Water Print Wednesday, 22 February 2006 00:00 A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly with pump-probe measurements. Using a combination of isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

217

Quasinormal modes for the SdS black hole : an analytical approximation scheme  

E-Print Network [OSTI]

Quasinormal modes for scalar field perturbations of a Schwarzschild-de Sitter (SdS) black hole are investigated. An analytical approximation is proposed for the problem. The quasinormal modes are evaluated for this approximate model in the limit when black hole mass is much smaller than the radius of curvature of the spacetime. The model mirrors some striking features observed in numerical studies of time behaviour of scalar perturbations of the SdS black hole. In particular, it shows the presence of two sets of modes relevant at two different time scales, proportional to the surface gravities of the black hole and cosmological horizons respectively. These quasinormal modes are not complete - another feature observed in numerical studies. Refinements of this model to yield more accurate quantitative agreement with numerical studies are discussed. Further investigations of this model are outlined, which would provide a valuable insight into time behaviour of perturbations in the SdS spacetime.

V. Suneeta

2003-03-31T23:59:59.000Z

218

Cathodic reduction of hexavalent chromium coupled with electricity generation achieved by reverse-electrodialysis processes using salinity gradients  

Science Journals Connector (OSTI)

Abstract A new approach for the simultaneous generation of electric energy and the treatment of waters contaminated by recalcitrant pollutants using salinity gradients was proposed. Reverse electrodialysis allows for the generation of electric energy from salinity gradients. Indeed, the utilization of different salt concentrations gives a potential difference between the electrodes which allows the generation of electric energy by using suitable electrolytes and an external circuit. The simultaneous generation of electric energy and the treatment of waters contaminated by Cr(VI) was successfully achieved for the first time by reverse electrodialysis processes using salinity gradients and proper redox processes. The effect on the process of many operative parameters, such as the extent of the salinity gradient, the number of membrane pairs in the stack, the initial concentration of Cr(VI), the concentration of the supporting electrolyte and the flow rates of the solutions fed in the stack, was also investigated.

O. Scialdone; A. DAngelo; E. De Lum; A. Galia

2014-01-01T23:59:59.000Z

219

A Sparsity Preserving Stochastic Gradient Method for Composite ...  

E-Print Network [OSTI]

Apr 23, 2011 ... Abstract: We propose new stochastic gradient algorithms for solving convex composite optimization problems. In each iteration, our algorithms...

Qihang Lin

2011-04-23T23:59:59.000Z

220

A Sparsity Preserving Stochastic Gradient Method for Composite ...  

E-Print Network [OSTI]

Apr 23, 2011 ... We propose new stochastic gradient algorithms for solving convex composite optimization problems. In each iteration, our algorithms utilize a...

2011-04-23T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Policy Gradient Methods: Variance Reduction and Stochastic Convergence .  

E-Print Network [OSTI]

??In a reinforcement learning task an agent must learn a policy for performing actions so as to perform well in a given environment. Policy gradient (more)

Greensmith, Evan

2008-01-01T23:59:59.000Z

222

Microconvection effects at double?diffusive gradient zone boundaries  

Science Journals Connector (OSTI)

Microconvection in double?diffusive gradient zones is predicted to occur near the zone boundaries because of effects of boundary undulation and temperature modulation caused by impinging thermals in adjacent convecting zones. The equations that govern convective motion in a double?diffusive horizontal slab are solved for boundary conditions that incorporate these effects. Solution of these equations predicts a weakened salinity gradient near the gradient zone boundary between the rising thermals. When the salinity gradient is too weak instability occurs taking the form of descending plumes which are seen in experiments.

John R. Hull; Yojana Katti

1988-01-01T23:59:59.000Z

223

Evapotranspiration along an elevation gradient in California's Sierra Nevada  

E-Print Network [OSTI]

Soil-moisture use by mixed conifer forest in a summer- dryforest, Sierra mixed conifer forest, and Subalpine forest)Climate Gradient Sierran Mixed Conifer Forest Sierra Climate

Goulden, M. L.; Anderson, R. G.; Bales, R. C.; Kelly, A. E.; Meadows, M.; Winston, G. C.

2012-01-01T23:59:59.000Z

224

An inexact accelerated proximal gradient method for large scale ...  

E-Print Network [OSTI]

The accelerated proximal gradient (APG) method, first proposed by Nesterov, and later refined by Beck and Teboulle, and studied in a unifying manner by Tseng.

2011-09-09T23:59:59.000Z

225

An accelerated proximal gradient algorithm for nuclear norm ...  

E-Print Network [OSTI]

Mar 27, 2009 ... An accelerated proximal gradient algorithm for nuclear norm regularized least squares problems. Kim-Chuan Toh (mattohkc ***at*** nus.edu.sg)

Kim-Chuan Toh

2009-03-27T23:59:59.000Z

226

Analysis of natural gradient descent for multilayer neural networks  

Science Journals Connector (OSTI)

Natural gradient descent is a principled method for adapting the parameters of a statistical model on-line using an underlying Riemannian parameter space to redefine the direction of steepest descent. The algorithm is examined via methods of statistical physics that accurately characterize both transient and asymptotic behavior. A solution of the learning dynamics is obtained for the case of multilayer neural network training in the limit of large input dimension. We find that natural gradient learning leads to optimal asymptotic performance and outperforms gradient descent in the transient, significantly shortening or even removing plateaus in the transient generalization performance that typically hamper gradient descent training.

Magnus Rattray and David Saad

1999-04-01T23:59:59.000Z

227

Supermassive black holes from supermassive stars  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Supermassive black holes from supermassive stars Supermassive black holes from supermassive stars 1663 Los Alamos science and technology magazine Latest Issue:November 2013 All Issues » submit Supermassive black holes from supermassive stars Supermassive stars in the early universe gave supermassive black holes a head start March 25, 2013 simulations suggest that star formation conditions back then allowed the first stars to become supermassive themselves In this simulation, a black hole that was just formed by the collapse of a supermassive star is surrounded by a distribution of gas (color indicates density). Because the black hole (located at the center but too small to see) grows by consuming the available gas, simulations like this one help determine how quickly the black hole can grow. The progenitor of this black

228

THE EXTENSIVE AGE GRADIENT OF THE CARINA DWARF GALAXY  

SciTech Connect (OSTI)

The evolution of small systems such as dwarf spheroidal galaxies (dSphs) is likely to have been a balance between external environmental effects and internal processes within their own relatively shallow potential wells. Assessing how strong such environmental interactions may have been is therefore an important element in understanding the baryonic evolution of dSphs and their derived dark matter distribution. Here we present results from a wide-area CTIO/MOSAIC II photometric survey of the Carina dSph, reaching down to about two magnitudes below the oldest main-sequence turnoff (MSTO). This data set enables us to trace the structure of Carina in detail out to very large distances from its center, and as a function of stellar age. We observe the presence of an extended structure made up primarily of ancient MSTO stars, at distances between 25' and 60' from Carina's center, confirming results in the literature that Carina extends well beyond its nominal tidal radius. The large number statistics of our survey reveals features such as isophote twists and tails that were undetected in other previous, shallower surveys. This is the first time that such unambiguous signs of tidal disruption have been found in a Milky Way 'classical' dwarf other than Sagittarius. We also demonstrate the presence of a negative age gradient in Carina directly from its MSTOs, and trace it out to very large distances from the galaxy center. The signs of interaction with the Milky Way make it unclear whether the age gradient was already in place before Carina underwent tidal disruption.

Battaglia, G. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Irwin, M. [Institute of Astronomy, Madingley Road, Cambridge CB03 0HA (United Kingdom); Tolstoy, E.; De Boer, T. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Mateo, M., E-mail: gbattaglia@oabo.inaf.it [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090 (United States)

2012-12-20T23:59:59.000Z

229

Mass without radiation: heavily obscured AGN, the X-ray Background and the Black Hole Mass Density  

E-Print Network [OSTI]

A recent revision of black hole scaling relations (Kormendy & Ho 2013), indicates that the local mass density in black holes should be increased by up to a factor of five with respect to previously determined values. The local black hole mass density is connected to the mean radiative efficiency of accretion through the time integral of the AGN volume density and a significant increase of the local black holes mass density would have interesting consequences on AGN accretion properties and demography. One possibility to explain a large black hole mass density is that most of the Black Hole growth is via radiatively inefficient channels such as super Eddington accretion, however, given the intrinsic degeneracies in the Soltan argument, this solution is not unique. Here we show how it is possible to accommodate a larger fraction of heavily buried, Compton thick AGN, without violating the limit imposed by the hard X-ray and mid-infrared backgrounds spectral energy density.

Comastri, A; Marconi, A; Risaliti, G; Salvati, M

2015-01-01T23:59:59.000Z

230

Optimization in the Parikh-Wilczek tunneling model of Hawking radiation for Kerr-Newman Black Holes  

E-Print Network [OSTI]

In this short report, we investigate the mutual information hidden in the Parikh-Wilczek tunneling model of Hawking radiation for Kerr-Newman black holes. By assuming the radiation as an optimization process, we discuss its effect on time evolution of rotating (charged and uncharged) black holes. For uncharged rotating black holes evaporating under the maximum mutual information optimization, their scale invariant rotation parameter $a_*=a/M$ is almost constant at the early stage but rapidly increase at the very last stage of the evaluation process. The value of rotation parameter at the final state of evaporation depends on the initial condition of the black hole. We also found that the presence of electric charge can cause the black holes lose their angular momentum more rapidly than they lose mass. The charged-rotating black holes asymptotically approach a state which is described by $a_*= 0$ and $Q/M = 1$.

Auttakit Chatrabhuti; Khem Upathambhakul

2014-03-17T23:59:59.000Z

231

Accelerating and rotating black holes  

E-Print Network [OSTI]

An exact solution of Einstein's equations which represents a pair of accelerating and rotating black holes (a generalised form of the spinning C-metric) is presented. The starting point is a form of the Plebanski-Demianski metric which, in addition to the usual parameters, explicitly includes parameters which describe the acceleration and angular velocity of the sources. This is transformed to a form which explicitly contains the known special cases for either rotating or accelerating black holes. Electromagnetic charges and a NUT parameter are included, the relation between the NUT parameter $l$ and the Plebanski-Demianski parameter $n$ is given, and the physical meaning of all parameters is clarified. The possibility of finding an accelerating NUT solution is also discussed.

J. B. Griffiths; J. Podolsky

2005-07-06T23:59:59.000Z

232

Black Holes at the LHC  

E-Print Network [OSTI]

In these two lectures, we will address the topic of the creation of small black holes during particle collisions in a ground-based accelerator, such as LHC, in the context of a higher-dimensional theory. We will cover the main assumptions, criteria and estimates for their creation, and we will discuss their properties after their formation. The most important observable effect associated with their creation is likely to be the emission of Hawking radiation during their evaporation process. After presenting the mathematical formalism for its study, we will review the current results for the emission of particles both on the brane and in the bulk. We will finish with a discussion of the methodology that will be used to study these spectra, and the observable signatures that will help us identify the black-hole events.

Panagiota Kanti

2008-02-15T23:59:59.000Z

233

Down hole periodic seismic generator  

DOE Patents [OSTI]

A down hole periodic seismic generator system for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.

Hardee, Harry C. (Albuquerque, NM); Hills, Richard G. (Las Cruces, NM); Striker, Richard P. (Albuquerque, NM)

1989-01-01T23:59:59.000Z

234

Primordial black hole minimum mass  

SciTech Connect (OSTI)

In this paper we revisit thermodynamic constraints on primordial black hole (PBH) formation in the early universe. Under the assumption that PBH mass is equal to the cosmological horizon mass, one can use the 2nd Law of Thermodynamics to put a lower limit on the PBH mass. In models of PBH formation, however, PBHs are created at some fraction of the horizon mass. We show that this thermodynamic constraint still holds for subhorizon PBH formation.

Chisholm, James R. [Institute for Fundamental Theory, University of Florida, Gainesville, Florida 32611-8440 (United States)

2006-08-15T23:59:59.000Z

235

Backdraft: String Creation in an Old Schwarzschild Black Hole  

E-Print Network [OSTI]

We analyze string production in the background of a Schwarzschild black hole, after developing first quantized methods which capture string-theoretic nonadiabatic effects which can exceed naive extrapolations of effective field theory. Late-time infalling observers are strongly boosted in the near horizon region relative to early observers and formation matter. In the presence of large boosts in flat spacetime, known string and D-brane scattering processes exhibit enhanced string production, even for large impact parameter. This suggests the possibility that the nonadiabatic dynamics required to realize the firewall proposal of AMPS occurs for old black holes, with the late-time observer catalyzing the effect. After setting up this dynamical thought experiment, we focus on a specific case: the production of open strings stretched D-particles, at least one of which falls in late (playing the role of a late time observer). For relatively boosted D-branes, we precisely recover earlier results of Bachas, McAllister and Mitra which we generalize to brane trajectories in the black hole geometry. For two classes of late-time probes, we find a regime of significant non-adiabaticity by horizon crossing, assessing its dependence on the boost in each case. Closed string probes, as well as additional effects in D-brane scattering, may produce other significant non-adiabatic effects depending on the boost, something we leave for further work.

Eva Silverstein

2014-02-21T23:59:59.000Z

236

Quantum Geometry and Black Holes  

E-Print Network [OSTI]

We present an overall picture of the advances in the description of black hole physics from the perspective of loop quantum gravity. After an introduction that discusses the main conceptual issues we present some details about the classical and quantum geometry of isolated horizons and their quantum geometry and then use this scheme to give a natural definition of the entropy of black holes. The entropy computations can be neatly expressed in the form of combinatorial problems solvable with the help of methods based on number theory and the use of generating functions. The recovery of the Bekenstein-Hawking law and corrections to it is explained in some detail. After this, due attention is paid to the discussion of semiclassical issues. An important point in this respect is the proper interpretation of the horizon area as the energy that should appear in the statistical-mechanical treatment of the black hole model presented here. The chapter ends with a comparison between the microscopic and semiclassical app...

G., J Fernando Barbero

2015-01-01T23:59:59.000Z

237

Entanglement entropy of black holes  

E-Print Network [OSTI]

The entanglement entropy is a fundamental quantity which characterizes the correlations between sub-systems in a larger quantum-mechanical system. For two sub-systems separated by a surface the entanglement entropy is proportional to the area of the surface and depends on the UV cutoff which regulates the short-distance correlations. The geometrical nature of the entanglement entropy calculation is particularly intriguing when applied to black holes when the entangling surface is the black hole horizon. I review a variety of aspects of this calculation: the useful mathematical tools such as the geometry of spaces with conical singularities and the heat kernel method, the UV divergences in the entropy and their renormalization, the logarithmic terms in the entanglement entropy in 4 and 6 dimensions and their relation to the conformal anomalies. The focus in the review is on the systematic use of the conical singularity method. The relations to other known approaches such as 't Hooft's brick wall model and the Euclidean path integral in the optical metric are discussed in detail. The puzzling behavior of the entanglement entropy due to fields which non-minimally couple to gravity is emphasized. The holographic description of the entanglement entropy of the black hole horizon is illustrated on the two- and four-dimensional examples. Finally, I examine the possibility to interpret the Bekenstein-Hawking entropy entirely as the entanglement entropy.

Sergey N. Solodukhin

2011-04-19T23:59:59.000Z

238

Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals  

SciTech Connect (OSTI)

Dynamics of hole storage in spherical Ge nanocrystals (NCs) formed by a two step dewetting/nucleation process on an oxide layer grown on an n-doped <001> silicon substrate is studied using a nano-electron beam induced current technique. Carrier generation is produced by an electron beam irradiation. The generated current is collected by an atomic force microscope--tip in contact mode at a fixed position away from the beam spot of about 0.5 {mu}m. This distance represents the effective diffusion length of holes. The time constants of holes charging are determined and the effect of the NC size is underlined.

Marchand, A.; El Hdiy, A.; Troyon, M. [Laboratoire de Recherche en Nanosciences, Bat. 6, case no 15, UFR Sciences, Universite de Reims Champagne Ardenne, 51687 Reims Cedex 2 (France); Amiard, G.; Ronda, A.; Berbezier, I. [IM2NP, Faculte des Sciences et Techniques, Campus de Saint Jerome - Case 142, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France)

2012-04-16T23:59:59.000Z

239

Were Archaean continental geothermal gradients much steeper than today?  

Science Journals Connector (OSTI)

... km depth) did not generally exceed 800 C. From this they deduce a surface geothermal gradient of less than 23 C km'1 compared with 17 C km'1 in ... P-T determinations on Archaean granulites (summarised in ref. 2) their calculation of the geothermal gradient does not comply with conductive properties and distribution of heat producing elements within the ...

S. A. DRURY

1978-08-17T23:59:59.000Z

240

Energy Conversion from Salinity Gradients by Forward OsmosisElectrokinetics  

Science Journals Connector (OSTI)

Energy Conversion from Salinity Gradients by Forward OsmosisElectrokinetics ... Through the use of a salinity gradient, a suction force is created to induce a hydrodynamic flow in the FO submodule based on the principle of FO. ... Kiviat, F. E.Energy Recovery from Saline Water by Means of Electrochemical Cells Science 1976, 194, 719 720 ...

Yanmei Jiao; Chun Yang; Yuejun Kang

2014-03-12T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Black Holes, Firewalls and Chaos from Gravitational Collapse  

E-Print Network [OSTI]

One of the most spectacular predictions of the general theory of relativity is the black hole, an object that plays a central role in modern physics [1,2,3] and astrophysics [4,5]. Black holes are, however, plagued by fundamental paradoxes that remain unresolved to this day. First, the black hole event horizon is teleological in nature [6], which means that we need to know the entire future space-time of the universe to determine the current location of the horizon. This is essentially impossible. Second, any information carried by infalling matter is lost once the material falls through the event horizon. Even though the black hole may later evaporate by emitting Hawking radiation [7], the lost information does not reappear, which has the rather serious and disturbing consequence that quantum unitarity is violated [8]. Here we propose that the above paradoxes are restricted to a particular idealized model of collapse first studied in the 1930s [9, 10] in which the event horizon, which defines the boundary of...

Joshi, Pankaj S

2014-01-01T23:59:59.000Z

242

The Inside Story: Quasilocal Tachyons and Black Holes  

SciTech Connect (OSTI)

We analyze the fate of excitations in regions of closed string tachyon condensate, a question crucial for understanding unitarity in a class of black holes in string theory. First we introduce a simple new example of quasilocal tachyon condensation in a globally stable AdS/CFT background, and review tachyons' appearance in black hole physics. Then we calculate forces on particles and fields in a tachyon phase using a field theoretic model with spatially localized exponentially growing time dependent masses. This model reveals two features, both supporting unitary evolution in the bulk of spacetime. First, the growing energy of fields sourced by sets of (real and virtual) particles in the tachyon phase yields outward forces on them, leaving behind only combinations which do not source any fields. Secondly, requiring the consistency of perturbative string theory imposes cancellation of a BRST anomaly, which also yields a restricted set of states. Each of these effects supports the notion of a black hole final state arising from string-theoretic dynamics replacing the black hole singularity.

Horowitz, Gary T.; /UC, Santa Barbara; Silverstein, Eva; /SLAC /Stanford U., Phys. Dept.

2006-01-13T23:59:59.000Z

243

Adaptive Event Horizon Tracking and Critical Phenomena in Binary Black Hole Coalescence  

E-Print Network [OSTI]

This work establishes critical phenomena in the topological transition of black hole coalescence. We describe and validate a computational front tracking event horizon solver, developed for generic studies of the black hole coalescence problem. We then apply this to the Kastor - Traschen axisymmetric analytic solution of the extremal Maxwell - Einstein black hole merger with cosmological constant. The surprising result of this computational analysis is a power law scaling of the minimal throat proportional to time. The minimal throat connecting the two holes obeys this power law during a short time immediately at the beginning of merger. We also confirm the behavior analytically. Thus, at least in one axisymmetric situation a critical phenomenon exists. We give arguments for a broader universality class than the restricted requirements of the Kastor - Traschen solution.

Scott A. Caveny; Richard A. Matzner

2003-04-30T23:59:59.000Z

244

Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function  

E-Print Network [OSTI]

Massive black hole binaries are naturally predicted in the context of the hierarchical model of structure formation. The binaries that manage to lose most of their angular momentum can coalesce to form a single remnant. In the last stages of this process, the holes undergo an extremely loud phase of gravitational wave emission, possibly detectable by current and future probes. The theoretical effort towards obtaining a coherent physical picture of the binary path down to coalescence is still underway. In this paper, for the first time, we take advantage of observational studies of active galactic nuclei evolution to constrain the efficiency of gas-driven binary decay. Under conservative assumptions we find that gas accretion toward the nuclear black holes can efficiently lead binaries of any mass forming at high redshift (> 2) to coalescence within the current time. The observed "downsizing" trend of the accreting black hole luminosity function further implies that the gas inflow is sufficient to drive light ...

Dotti, Massimo; Montuori, Carmen

2015-01-01T23:59:59.000Z

245

Chemical aspects of cylinder corrosion and a scenario for hole development  

SciTech Connect (OSTI)

In June 1990, two cylinders in the depleted UF{sub 6} cylinder storage yards at Portsmouth were discovered to have holes in their walls at the valve-end stiffening ring at a point below the level of the gas-solid interface of the UF{sub 6}. The cylinder with the larger hole, which extended under the stiffening ring, was stacked in a top row 13 years ago. The cylinder with the smaller hole had been stacked in a bottom row 4 years ago. The lifting lugs of the adjacent cylinders pointed directly at the holes. A Cylinder Investigating Committee was appointed to determine the cause or causes of the holes and to assess the implications of these findings. This report contains a listing of the chemically related facts established by the Investigating Committee with the cooperation of the Operations and Technical Support Divisions at the Portsmouth Gaseous Diffusion Plant, the scenario developed to explain these findings and some implications of this scenario. In summary, the interrelated reactions of water, solid UF{sub 6} and iron presented by R. L. Ritter are used to develop a scenario which explains the observations and deductions made during the investigation. The chemical processes are intimately related to the course of the last three of the four stages of hole development. A simple model is proposed which permits semiquantitative prediction of such information as the HF loss rates as a function of time, the rate of hole enlargement, the time to hydrolyze a cylinder of UF{sub 6} and the approximate size of the hole. The scenario suggests that the environmental consequences associated with a developing hole in a depleted UF{sub 6} cylinder are minimal for the first several years but will become significant if too many years pass before detection. The overall environmental picture is presented in more detail elsewhere.

Barber, E.J. [Martin Marietta Energy Systems, Oak Ridge, TN (United States)

1991-12-31T23:59:59.000Z

246

Colorful quantum black holes at the LHC  

E-Print Network [OSTI]

We examine the LHC phenomenology of quantum black holes in models of TeV gravity. By quantum black holes we mean black holes of the smallest masses and entropies, far from the semiclassical regime. These black holes are formed and decay over short distances, and typically carry SU(3) color charges inherited from their parton progenitors. Based on a few minimal assumptions, such as gauge invariance, we identify interesting signatures for quantum black hole decay such as 2 jets, jet + hard photon, jet + missing energy and jet + charged lepton, which should be readily visible above background. The detailed phenomenology depends heavily on whether one requires a Lorentz invariant, low-energy effective field theory description of black hole processes.

Xavier Calmet; Wei Gong; Stephen D. H. Hsu

2008-06-27T23:59:59.000Z

247

Spinning Black Holes as Particle Accelerators  

Science Journals Connector (OSTI)

It has recently been pointed out that particles falling freely from rest at infinity outside a Kerr black hole can in principle collide with an arbitrarily high center of mass energy in the limiting case of maximal black hole spin. Here we aim to elucidate the mechanism for this fascinating result, and to point out its practical limitations, which imply that ultraenergetic collisions cannot occur near black holes in nature.

Ted Jacobson and Thomas P. Sotiriou

2010-01-14T23:59:59.000Z

248

Black hole entropy: inside or out?  

E-Print Network [OSTI]

A trialogue. Ted, Don, and Carlo consider the nature of black hole entropy. Ted and Carlo support the idea that this entropy measures in some sense ``the number of black hole microstates that can communicate with the outside world.'' Don is critical of this approach, and discussion ensues, focusing on the question of whether the first law of black hole thermodynamics can be understood from a statistical mechanics point of view.

Ted Jacobson; Donald Marolf; Carlo Rovelli

2005-01-14T23:59:59.000Z

249

Interaction of fermions with black holes  

SciTech Connect (OSTI)

Bekenstein and Meisels used statistical thermodynamic arguments to obtain the probability distribution of fermions emitted by a black hole when a fermion is incident. In contrast with Bekenstein and Meisels, we model the black hole as a perfect blackbody surrounded by a mirror. Our probability distribution for emitted fermions agrees with the probability distribution of Bekenstein and Meisels, but the interpretation of how fermions interact with the black hole is different from the interpreteation given by Bekenstein and Meisels.

Jones T.O. III

1986-04-15T23:59:59.000Z

250

Electromagnetic Beams Overpass the Black Hole Horizon  

E-Print Network [OSTI]

We show that the electromagnetic excitations of the Kerr black hole have very strong back reaction on metric. In particular, the electromagnetic excitations aligned with the Kerr congruence form the light-like beams which overcome horizon, forming the holes in it, which allows matter to escape interior. So, there is no information lost inside the black hole. This effect is based exclusively on the analyticity of the algebraically special solutions.

Alexander Burinskii

2008-06-16T23:59:59.000Z

251

Efficient and robust gradient enhanced Kriging emulators.  

SciTech Connect (OSTI)

%E2%80%9CNaive%E2%80%9D or straight-forward Kriging implementations can often perform poorly in practice. The relevant features of the robustly accurate and efficient Kriging and Gradient Enhanced Kriging (GEK) implementations in the DAKOTA software package are detailed herein. The principal contribution is a novel, effective, and efficient approach to handle ill-conditioning of GEK's %E2%80%9Ccorrelation%E2%80%9D matrix, RN%CC%83, based on a pivoted Cholesky factorization of Kriging's (not GEK's) correlation matrix, R, which is a small sub-matrix within GEK's RN%CC%83 matrix. The approach discards sample points/equations that contribute the least %E2%80%9Cnew%E2%80%9D information to RN%CC%83. Since these points contain the least new information, they are the ones which when discarded are both the easiest to predict and provide maximum improvement of RN%CC%83's conditioning. Prior to this work, handling ill-conditioned correlation matrices was a major, perhaps the principal, unsolved challenge necessary for robust and efficient GEK emulators. Numerical results demonstrate that GEK predictions can be significantly more accurate when GEK is allowed to discard points by the presented method. Numerical results also indicate that GEK can be used to break the curse of dimensionality by exploiting inexpensive derivatives (such as those provided by automatic differentiation or adjoint techniques), smoothness in the response being modeled, and adaptive sampling. Development of a suitable adaptive sampling algorithm was beyond the scope of this work; instead adaptive sampling was approximated by omitting the cost of samples discarded by the presented pivoted Cholesky approach.

Dalbey, Keith R.

2013-08-01T23:59:59.000Z

252

Thermodynamics of dilaton-axion black holes  

SciTech Connect (OSTI)

Considering a generalized action for the Einstein-Maxwell theory in four dimensions coupled to scalar and pseudoscalar fields, the thermodynamic properties of asymptotically flat black hole solutions in such a background are investigated. Bekenstein-Hawking area-entropy law is verified for these class of black holes. From the property of specific heat, it is shown that such black holes can be stable for a certain choice of the parameters like charge, mass, and the scalar vacuum expectation value. The possibility of a black hole phase transition is discussed in this context.

Ghosh, Tanwi; SenGupta, Soumitra [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Calcutta-700 032 (India)

2008-12-15T23:59:59.000Z

253

Black Holes: from Speculations to Observations  

E-Print Network [OSTI]

This paper provides a brief review of the history of our understanding and knowledge of black holes. Starting with early speculations on ``dark stars'' I discuss the Schwarzschild "black hole" solution to Einstein's field equations and the development of its interpretation from "physically meaningless" to describing the perhaps most exotic and yet "most perfect" macroscopic object in the universe. I describe different astrophysical black hole populations and discuss some of their observational evidence. Finally I close by speculating about future observations of black holes with the new generation of gravitational wave detectors.

Thomas W. Baumgarte

2006-04-13T23:59:59.000Z

254

Influence of the back reaction of the Hawking radiation upon black hole quasinormal modes  

Science Journals Connector (OSTI)

We consider the BTZ black hole surrounded by the conformal scalar field. Within general relativity, the resonant quasinormal (QN) modes dominate in the response of a black hole to external perturbations. At the same time, the metric of an evaporating black hole is affected by the Hawking radiation. We estimate the shift in the quasinormal spectrum of the BTZ black hole stipulated by the back reaction of the Hawking radiation. For the case of the (2+1)-dimensional black hole the corrected (by ??) metric is an exact solution [C. Martines and J. Zanelli, Phys. Rev. D 55, 3642 (1997)]. In addition, in this case quantum corrections come only from matter fields and not from graviton loops, that is, one can solve the problem of influence of the back reaction upon the QN ringing self-consistently. The dominant contribution to the corrections to the QNMs is simply a shift of ?2 proportional to -(?/M)3/2(4L2+M)?. It is negligible for large black holes but essential for small ones, giving rise to considerable increasing of the quality factor. Thus, the small evaporating black hole is expected to be a much better oscillator than a large one.

R. A. Konoplya

2004-08-18T23:59:59.000Z

255

Temperature, Energy, and Heat Capacity of Asymptotically Anti-De Sitter Black Holes  

E-Print Network [OSTI]

We investigate the thermodynamical properties of black holes in (3+1) and (2+1) dimensional Einstein gravity with a negative cosmological constant. In each case, the thermodynamic internal energy is computed for a finite spatial region that contains the black hole. The temperature at the boundary of this region is defined by differentiating the energy with respect to entropy, and is equal to the product of the surface gravity (divided by~$2\\pi$) and the Tolman redshift factor for temperature in a stationary gravitational field. We also compute the thermodynamic surface pressure and, in the case of the (2+1) black hole, show that the chemical potential conjugate to angular momentum is equal to the proper angular velocity of the black hole with respect to observers who are at rest in the stationary time slices. In (3+1) dimensions, a calculation of the heat capacity reveals the existence of a thermodynamically stable black hole solution and a negative heat capacity instanton. This result holds in the limit that the spatial boundary tends to infinity only if the comological constant is negative; if the cosmological constant vanishes, the stable black hole solution is lost. In (2+1) dimensions, a calculation of the heat capacity reveals the existence of a thermodynamically stable black hole solution, but no negative heat capacity instanton.

J. D. Brown; J. Creighton; R. B. Mann

1994-05-03T23:59:59.000Z

256

A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way  

Science Journals Connector (OSTI)

... in April/May 2002 thus probes the mass concentration at around 2,100 times the Schwarzschild radius of a 3 106M black hole. The pericentre distance radius of S2 ... because such a configuration would have a radius only a few times greater than the Schwarzschild radius of a black hole. However, it would be very hard to understand how ...

R. Schdel; T. Ott; R. Genzel; R. Hofmann; M. Lehnert; A. Eckart; N. Mouawad; T. Alexander; M. J. Reid; R. Lenzen; M. Hartung; F. Lacombe; D. Rouan; E. Gendron; G. Rousset; A.-M. Lagrange; W. Brandner; N. Ageorges; C. Lidman; A. F. M. Moorwood; J. Spyromilio; N. Hubin; K. M. Menten

2002-10-17T23:59:59.000Z

257

Locking Information in Black Holes  

Science Journals Connector (OSTI)

We show that a central presumption in the debate over black-hole information loss is incorrect. Ensuring that information not escape during evaporation does not require that it all remain trapped until the final stage of the process. Using the recent quantum information-theoretic result of locking, we show that the amount of information that must remain can be very small, even as the amount already radiated is negligible. Information need not be additive: A small system can lock a large amount of information, making it inaccessible. Only if the set of initial states is restricted can information leak.

John A. Smolin and Jonathan Oppenheim

2006-02-28T23:59:59.000Z

258

Determination of salinity gradient power potential in Qubec, Canada  

Science Journals Connector (OSTI)

Electrical energy can be produced from the chemical potential difference of two liquids with dissimilar salinities. This source of energy is known as salinity gradient power. In this paper the theory the technologies used to exploit the power the major challenges and their development trends are first presented. Then a modeling of fluxes across semi permeable membranes is proposed and validated. Next an energy balance study is done in order to estimate the power potential for a given salinity gradient system. By applying this study to several rivers in Quebec the salinity power gradient potential is estimated to 45 TWh/yr based on the minimal flow rate of each river.

Y. Berrouche; P. Pillay

2012-01-01T23:59:59.000Z

259

Dynamics of oscillating relativistic tori around Kerr black holes  

Science Journals Connector (OSTI)

......angular momentum discs around Schwarzschild black holes, namely that...transmission of the signal recycling mirror (Shoemaker 2004)]. This...angular momentum discs around Schwarzschild black holes were considered...accretion solution on to a Schwarzschild black hole (Michel 1972......

Olindo Zanotti; Jos A. Font; Luciano Rezzolla; Pedro J. Montero

2005-02-01T23:59:59.000Z

260

Ultrafast Core-Hole Induced Dynamics in Water  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly with pump-probe measurements. Using a combination of isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Ultrafast Core-Hole Induced Dynamics in Water  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly with pump-probe measurements. Using a combination of isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

262

Ultrafast Core-Hole Induced Dynamics in Water  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly with pump-probe measurements. Using a combination of isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

263

Universal optimal hole-doping concentration in single-layer high-temperature cuprate superconductors  

E-Print Network [OSTI]

We argue that in cuprate physics there are two types, hole content per CuO$_2$ plane ($P_{pl}$) and the corresponding hole content per unit volume ($P_{3D}$), of hole-doping concentrations for addressing physical properties that are two-dimensional (2D) and three-dimensional (3D) in nature, respectively. We find that superconducting transition temperature ($T_c$) varies systematically with $P_{3D}$ as a superconducting \\textquotedblleft $dome$\\textquotedblright with a universal optimal hole-doping concentration $P_{3D}^{opt.}$ = 1.6 $\\times$ 10$^{21}$ cm$^{-3}$ for single-layer high temperature superconductors. We suggest that $P_{3D}^{opt.}$ determines the upper bound of the electronic energy of underdoped single-layer high-$T_c$ cuprates.

T. Honma; P. H. Hor

2006-02-20T23:59:59.000Z

264

Black holes cannot support conformal scalar hair  

E-Print Network [OSTI]

It is shown that the only static asymptotically flat non-extrema black hole solution of the Einstein-conformally invariant scalar field equations having the scalar field bounded on the horizon, is the Schwarzschild one. Thus black holes cannot be endowed with conformal scalar hair of finite length.

T. Zannias

1994-09-14T23:59:59.000Z

265

The scattering matrix approach for the quantum black hole, an overview  

E-Print Network [OSTI]

If one assumes the validity of conventional quantum field theory in the vicinity of the horizon of a black hole, one does not find a quantum mechanical description of the entire black hole that even remotely resembles that of conventional forms of matter; in contrast with matter made out of ordinary particles one finds that, even if embedded in a finite volume, a black hole would be predicted to have a strictly continuous spectrum. Dissatisfied with such a result, which indeed hinges on assumptions concerning the horizon that may well be wrong, various investigators have now tried to formulate alternative approaches to the problem of ``quantizing" the black hole. We here review the approach based on the assumption of quantum mechanical purity and unitarity as a starting point, as has been advocated by the present author for some time, concentrating on the physics of the states that should live on a black hole horizon. The approach is shown to be powerful in not only producing promising models for the quantum black hole, but also new insights concerning the dynamics of physical degrees of freedom in ordinary flat space-time.

G. 't Hooft

1996-07-09T23:59:59.000Z

266

A gradient index sonic lens based on acoustic metamaterials  

Science Journals Connector (OSTI)

We report a method to design and characterize broadband gradient index lenses. The lenses are based on two?dimensional sonic crystals which are periodic arrangements of elastic cylinders embedded in air. It will be shown that gradient index sonic lenses built with rigid cylinders are more powerful than conventionally curved lenses. We also demonstrate that the designing possibilities increased by considering the mixture of two types of cylinders in the sonic crystal. So a gradient index lens with zero reflectance at the surface is proposed by employing a mixture of aerogel and rigid cylinders. Finally a multiple scatteringtheory has been employed to compare the performance of conventionally curved lenses and gradient index lenses. [Work supported by MEC of Spain and GVA of Valencia.

Jos Snchez?Dehesa; Daniel Torrent

2007-01-01T23:59:59.000Z

267

Potential use of hollow spheres in dual gradient drilling  

E-Print Network [OSTI]

The increasing number of significant deepwater discoveries has pushed the operator and service oil companies to focus their efforts on developing new technologies to drill in deeper water. Dual gradient drilling (DGD) will allow reaching deeper...

Vera Vera, Liliana

2012-06-07T23:59:59.000Z

268

Use of gradient magnets in low emittance electron storage rings  

SciTech Connect (OSTI)

The use of gradient magnets for a low emittance electron storage ring is discussed and a magnetic lattice for a 6 GeV electron energy synchrotron radiation source adopting this feature is presented.

Vignola, G.

1985-01-01T23:59:59.000Z

269

A three-term conjugate gradient method with sufficient descent ...  

E-Print Network [OSTI]

k?1yk?1. ,. (1.2) where yk?1 is defined by yk?1 = gk ? gk?1 and denotes the l2 ...... [15] M.R. Hestenes and E. Stiefel, Methods of conjugate gradients for solving

2009-11-02T23:59:59.000Z

270

Functionally gradient titanium-aluminide composites produced by laser cladding  

Science Journals Connector (OSTI)

The laser surface cladding of Ti-Al/TiB2...composites was investigated as a means of producing a functionally gradient material on a commercially pure Ti substrate. Single and double layers were produced. The pro...

J. H. Abboud; D. R. F. West; R. D. Rawlings

1994-07-01T23:59:59.000Z

271

A parametric study of thermomechanical behavior of functionally gradient materials  

E-Print Network [OSTI]

(FSDT) that accounts for the transverse shear strains and the rotations, coupled with a three dimensional heat conduction equation is formulated for a functionally gradient plate. Both problems are studied by varying the volume fraction of a ceramic...

Chin, Che-Doong

1996-01-01T23:59:59.000Z

272

The Hadley Circulation and the Weak Temperature Gradient Approximation  

Science Journals Connector (OSTI)

The weak temperature gradient (WTG) approximation is applied to simple shallow-water models of the Hadley circulation. While it is difficult to formally justify the use of the WTG approximation for this problem, the derived WTG solutions are ...

L. M. Polvani; A. H. Sobel

2002-05-01T23:59:59.000Z

273

Computational Inversion of Electron Tomography Images -Gradient Flows  

E-Print Network [OSTI]

Computational Inversion of Electron Tomography Images Using L2 -Gradient Flows Guoliang Xu 1) Ming Computing Institute of Computational Mathematics, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing 100190, China 2) Department of Computer Sciences and Institute

Texas at Austin, University of

274

Generation of Gradients Having Complex Shapes Using Microfluidic Networks  

E-Print Network [OSTI]

Generation of Gradients Having Complex Shapes Using Microfluidic Networks Stephan K. W. Dertinger, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138 This paper describes the generation each carrying different concentrations of substances laminarly and side-by-side generated step

Prentiss, Mara

275

A Tree-Ring Reconstruction of the Salinity Gradient in the Northern Estuary of San Francisco Bay  

E-Print Network [OSTI]

Ring Reconstruction of the Salinity Gradient in the Northernof the seasonal salinity gradient, or low salinity zone (the longitudinal salinity gradient in the northern estuary (

2011-01-01T23:59:59.000Z

276

Effects of interspecific competition and coastal oceanography on population dynamics of the Olympia oyster, Ostrea lurida, along estuarine gradients  

E-Print Network [OSTI]

across estuarine salinity gradients. Ecology 85:2539- Dalby,abundance along a salinity gradient. Ecology Lamb, E. G. andalong an estuarine salinity gradient. Oikos Etter, R. J.

Deck, Anna K.

2011-01-01T23:59:59.000Z

277

T-623: HP Business Availability Center Input Validation Hole...  

Broader source: Energy.gov (indexed) [DOE]

Business Availability Center Input Validation Hole Permits Cross-Site Scripting Attacks T-623: HP Business Availability Center Input Validation Hole Permits Cross-Site Scripting...

278

Three Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and Transition State Analogues. Three Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and Transition State Analogues....

279

Black hole foraging: feedback drives feeding  

E-Print Network [OSTI]

We suggest a new picture of supermassive black hole (SMBH) growth in galaxy centers. Momentum-driven feedback from an accreting hole gives significant orbital energy but little angular momentum to the surrounding gas. Once central accretion drops, the feedback weakens and swept-up gas falls back towards the SMBH on near-parabolic orbits. These intersect near the black hole with partially opposed specific angular momenta, causing further infall and ultimately the formation of a small-scale accretion disk. The feeding rates into the disk typically exceed Eddington by factors of a few, growing the hole on the Salpeter timescale and stimulating further feedback. Natural consequences of this picture include (i) the formation and maintenance of a roughly toroidal distribution of obscuring matter near the hole; (ii) random orientations of successive accretion disk episodes; (iii) the possibility of rapid SMBH growth; (iv) tidal disruption of stars and close binaries formed from infalling gas, resulting in visible fl...

Dehnen, Walter

2013-01-01T23:59:59.000Z

280

Black Hole Superradiance in Dynamical Spacetime  

E-Print Network [OSTI]

We study the superradiant scattering of gravitational waves by a nearly extremal black hole (dimensionless spin $a=0.99$) by numerically solving the full Einstein field equations, thus including backreaction effects. This allows us to study the dynamics of the black hole as it loses energy and angular momentum during the scattering process. To explore the nonlinear phase of the interaction, we consider gravitational wave packets with initial energies up to $10%$ of the mass of the black hole. We find that as the incident wave energy increases, the amplification of the scattered waves, as well as the energy extraction efficiency from the black hole, is reduced. During the interaction the apparent horizon geometry undergoes sizable nonaxisymmetric oscillations. The largest amplitude excitations occur when the peak frequency of the incident wave packet is above where superradiance occurs, but close to the dominant quasinormal mode frequency of the black hole.

William E. East; Fethi M. Ramazano?lu; Frans Pretorius

2014-03-14T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Osteochondral Interface Tissue Engineering using Macroscopic Gradients of Physicochemical Signals  

E-Print Network [OSTI]

of tissue interfaces. Yet, just because tissues are separated from one another by type, function, location, or anatomical prevalence, does not necessarily mean that the interfaces are as easily distinguishable, as the interfaces themselves are highly complex... not yield a true continuous gradient, it can have many discrete advantages over continuous gradients. Because of the inherent discontinuous fabrication methods (developing sections separately and fusing together), however, design effort must be placed...

Dormer, Nathan Henry

2011-04-25T23:59:59.000Z

282

Precisely mapping the magnetic field gradient in vacuum with an atom interferometer  

SciTech Connect (OSTI)

The magnetic field gradient has been measured with an atom interferometer using the magnetic sublevels of {sup 87}Rb atoms. The Doppler-insensitive measurement effectively eliminates the contribution from gravity and background vibration noise, and the differential measurement also can reject some systematic errors. A resolution of 300 pT/mm has been demonstrated with a 90-s integration time and a spatial resolution of 1.4 mm. The gradiometer was then used to measure the magnetic field gradient in an ultrahigh-vacuum environment. The technique will also be very useful to subtract the systematic error arising from the magnetic field inhomogeneity in precision atom-interferometry experiments, such as gravity measurement.

Zhou Minkang; Hu Zhongkun; Duan Xiaochun; Sun Buliang; Zhao Jinbo; Luo Jun [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-12-15T23:59:59.000Z

283

Flow from a Tank Consider water flowing from a tank with water through a hole in its bottom. Denote  

E-Print Network [OSTI]

Flow from a Tank Consider water flowing from a tank with water through a hole in its bottom. Denote by h(t) the height of water in the tank at time t, v(t) the speed of the water leaving through the hole at time t, A(h) the cross-sectional area of the tank at height h and a the cross- sectional area

Feldman, Joel

284

Ammonium Bicarbonate Transport in Anion Exchange Membranes for Salinity Gradient Energy  

Science Journals Connector (OSTI)

Ammonium Bicarbonate Transport in Anion Exchange Membranes for Salinity Gradient Energy ... Current status of ion exchange membranes for power generation from salinity gradients ...

Geoffrey M. Geise; Michael A. Hickner; Bruce E. Logan

2013-08-22T23:59:59.000Z

285

E-Print Network 3.0 - alternating gradient focusing Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

gradient focusing Page: << < 1 2 3 4 5 > >> 1 Gradient Estimation in Global Optimization Algorithms Megan Hazen, Member, IEEE and Maya R. Gupta, Member, IEEE Summary:...

286

Single molecule studies of meso/macro porous silica materials and gradient films.  

E-Print Network [OSTI]

??The preparation of mesoporous/macroporous silica materials and polarity gradient thin film are introduced in this thesis. These porous silica materials and gradient materials have the (more)

Ye, Fangmao

2009-01-01T23:59:59.000Z

287

Spherical non-linear absorption of cosmological scalar fields onto a black hole  

E-Print Network [OSTI]

In this paper we track the non-linear spherical evolution of a massless scalar field onto a Schwarzschild black hole space-time as a first approximation to the accretion of cosmologically motivated classical scalar fields. We perform an analysis related to wave packets described by wave number and width. We study various values of the wave number k, and found that for k = 0 and width packets bigger than the Schwarzschild radius, the absorption is not total. In the cases we studied for k > 0, the black hole absorbs the total amount of energy density of the scalar field moving toward the horizon. Our results indicate that assuming spherical symmetry, in the non-linear regime, there are cases for which scalar fields are allowed to survive outside black holes and may eventually have life-times consistent with cosmological time scales.

F. S. Guzman; F. D. Lora-Clavijo

2012-01-17T23:59:59.000Z

288

In situ experimental study of reed leaf decomposition along a full salinity gradient  

Science Journals Connector (OSTI)

An experimental study on Phragmites australis leaf litter decomposition was conducted in the estuarine environment, Ria de Aveiro, Western Portugal, using the leaf-bag technique, with fine- (1mm) and coarse-mesh (5mm) bags. The leaf bags were placed in the field sites at day 0, covering a complete salinity gradient, and replicates were collected over time, at days 3 (leaching), 7, 15, 30 and 60. The biomass loss through the leaching phase, about 20% of the initial leaf mass, was independent of both the salinity and the bag mesh size. The biomass decay pattern along the salinity gradient varied through time and presented strong similarities between the two mesh sizes, with the remaining biomass always lower in the 5mm mesh-size bags. At days 7 and 15, the lowest remaining biomass was observed at the head of the estuary, the preferential distribution area of P. australis. At day 30, the remaining biomass was higher in the marine area and diminished under a direct relationship with salinity, reaching the lowest value in the freshwater environment, with values ranging from 66% to 44% of the initial weight in 5mm bags, and from 79% to 51% in 1mm bags. The largest heterogeneity in the remaining biomass among the study areas positioned along the salinity gradient was found close to days 30 (5mm) and 40 (1mm). The overall results indicate that the relationship between leaf decay rate and salinity depends on the decay time considered (k15, k30 or k60) and, for the later stages (k60), also on the leaf-bag mesh size. This implies that the use of leaf litter decay rates as a functional indicator in transitional waters will need to take into consideration the factor location in the salinity gradient and leaf litter stage at which the decay rate is determined. The differences between the decay rates with the mesh size acted mainly at the level of the absolute k value and not at the level of the pattern along the salinity gradient. Even so, the data obtained at the mouth of the estuary, in the area closest to a fully marine environment, indicated that after the initial biomass loss through leaching, P.australis decayed either very slowly, in the 5mm, or not at all, in the 1mm mesh bags.

Victor Quintino; Franca Sangiorgio; Fernando Ricardo; Renato Mamede; Adlia Pires; Rosa Freitas; Ana Maria Rodrigues; Alberto Basset

2009-01-01T23:59:59.000Z

289

The Self-Regulated Growth of Supermassive Black Holes  

E-Print Network [OSTI]

We present a series of simulations of the self--regulated growth of supermassive black holes (SMBHs) in galaxies via three different fueling mechanisms: major mergers, minor mergers, and disk instabilities. The SMBHs in all three scenarios follow the same black hole fundamental plane (BHFP) and correlation with bulge binding energy seen in simulations of major mergers, and observed locally. Furthermore, provided that the total gas supply is significantly larger than the mass of the SMBH, its limiting mass is not influenced by the amount of gas available or the efficiency of black hole growth. This supports the assertion that SMBHs accrete until they reach a critical mass at which feedback is sufficient to unbind the gas locally, terminating the inflow and stalling further growth. At the same time, while minor and major mergers follow the same projected correlations (e.g., the $M_{BH}-\\sigma$ and Magorrian relations), SMBHs grown via disk instabilities do not, owing to structural differences between the host bulges. This finding is supported by recent observations of SMBHs in pseudobulges and bulges in barred systems, as compared to those hosted by classical bulges. Taken together, this provides support for the BHFP and binding energy correlations as being more "fundamental" than other proposed correlations in that they reflect the physical mechanism driving the co-evolution of SMBHs and spheroids.

Joshua D. Younger; Philip F. Hopkins; T. J. Cox; Lars Hernquist

2008-04-17T23:59:59.000Z

290

Slim Holes for Small Power Plants  

SciTech Connect (OSTI)

Geothermal research study at Sandia National Laboratories has conducted a program in slimhole drilling research since 1992. Although our original interest focused on slim holes as an exploration method, it has also become apparent that they have substantial potential for driving small-scale, off-grid power plants. This paper summarizes Sandia's slim-hole research program, describes technology used in a ''typical'' slimhole drilling project, presents an evaluation of using slim holes for small power plants, and lists some of the research topics that deserve further investigation.

Finger, John T.

1999-08-06T23:59:59.000Z

291

Chaotic string-capture by black hole  

Science Journals Connector (OSTI)

We consider a macroscopic charge-current carrying (cosmic) string in the background of a Schwarzschild black hole. The string is taken to be circular and is allowed to oscillate and to propagate in the direction perpendicular to its plane (that is parallel to the equatorial plane of the black hole). Numerical investigations indicate that the system is non-integrable, but the interaction with the gravitational field of the black hole still gives rise to various qualitatively simple processes like `adiabatic capture' and `string transmutation'.

A L Larsen

1994-01-01T23:59:59.000Z

292

Filling the disk hollow following binary black hole merger: The transient accretion afterglow  

SciTech Connect (OSTI)

Tidal torques from a binary black hole empty out the central regions in any circumbinary gaseous accretion disk. The balance between tidal torques and viscosity maintain the inner edge of the disk at a radius r{approx}1.5a-2a, where a is the binary semimajor axis. Eventually, the inspiraling binary decouples from the disk and merges, leaving behind a central hollow (''donut hole'') in the disk orbiting the remnant black hole. We present a simple, time-dependent, Newtonian calculation that follows the secular (viscous) evolution of the disk as it fills up the hollow down to the black hole innermost stable circular orbit and then relaxes to stationary equilibrium. We use our model to calculate the electromagnetic radiation (''afterglow'') spectrum emitted during this transient accretion epoch. Observing the temporal increase in the total electromagnetic flux and the hardening of the spectrum as the donut hole fills may help confirm a binary black hole merger detected by a gravitational wave interferometer. We show how the very existence of the initial hollow can lead to super-Eddington accretion during this secular phase if the rate is not very far below Eddington prior to decoupling. Our model, though highly idealized, may be useful in establishing some of the key parameters, thermal emission features and scalings that characterize this transient. It can serve as a guide in the design and calibration of future radiation-magnetohydrodynamic simulations in general relativity.

Shapiro, Stuart L. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2010-01-15T23:59:59.000Z

293

Black Hole Instabilities and Exponential Growth  

E-Print Network [OSTI]

Recently, a general analysis has been given of the stability with respect to axisymmetric perturbations of stationary-axisymmetric black holes and black branes in vacuum general relativity in arbitrary dimensions. It was shown that positivity of canonical energy on an appropriate space of perturbations is necessary and sufficient for stability. However, the notions of both "stability" and "instability" in this result are significantly weaker than one would like to obtain. In this paper, we prove that if a perturbation of the form $\\pounds_t \\delta g$---with $\\delta g$ a solution to the linearized Einstein equation---has negative canonical energy, then that perturbation must, in fact, grow exponentially in time. The key idea is to make use of the $t$- or ($t$-$\\phi$)-reflection isometry, $i$, of the background spacetime and decompose the initial data for perturbations into their odd and even parts under $i$. We then write the canonical energy as $\\mathscr E\\ = \\mathscr K + \\mathscr U$, where $\\mathscr K$ and $...

Prabhu, Kartik

2015-01-01T23:59:59.000Z

294

Borehole gravity meter survey in drill hole USW G-4, Yucca Mountain Area, Nye County, Nevada  

SciTech Connect (OSTI)

Drill hole USW G-4 was logged with the US Geological Survey borehole gravity meter (BHGM) BH-6 as part of a detailed study of the lithostratigraphic units penetrated by this hole. Because the BHGM measures a larger volume of rock than the conventional gamma-gamma density tool, it provides an independent and more accurate measurement of the in situ average bulk density of thick lithologic units. USW G-4 is an especially important hole because of its proximity to the proposed exploratory shaft at Yucca Mountain. The BHGM data were reduced to interval densities using a free-air gradient (F) of 0.3083 mGal./m (0.09397 mGal/ft) measured at the drill site. The interval densities were further improved by employing an instrument correction factor of 1.00226. This factor was determined from measurements obtained by taking gravity meter BH-6 over the Charleston Peak calibration loop. The interval density data reported herein, should be helpful for planning the construction of the proposed shaft.

Healey, D.L.; Clutsom, F.G.; Glover, D.A.

1986-12-31T23:59:59.000Z

295

Binary Black Hole Accretion Flows From a Misaligned Circumbinary Disk  

Science Journals Connector (OSTI)

......mass-accretion-rate variation per binary...because each black hole passes across the circumbinary...mass-accretion-rate variation per binary...holes|black hole physics|Galaxies: nuclei...because each black hole passes across the circumbinary...the mass accretion rates is also independent......

Kimitake Hayasaki; Hideki Saito; Shin Mineshige

2013-08-25T23:59:59.000Z

296

(1) Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA(1) Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA (2) Harvard Medical School, Boston, MA 02114 USA(2) Harvard Medical School, Boston  

E-Print Network [OSTI]

(1) Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA(1) Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA (2) Harvard Medical School, Boston, MA 02114 USA(2) Harvard Medical School, Boston, MA 02114 USA (3) Section on Auditory Mechanics, NIDCD

297

COLOR AND STELLAR POPULATION GRADIENTS IN PASSIVELY EVOLVING GALAXIES AT z {approx} 2 FROM HST/WFC3 DEEP IMAGING IN THE HUBBLE ULTRA DEEP FIELD  

SciTech Connect (OSTI)

We report the detection of color gradients in six massive (stellar mass (M{sub star}) > 10{sup 10} M{sub sun}) and passively evolving (specific star formation rate <10{sup -11} yr{sup -1}) galaxies at redshift 1.3 < z < 2.5 identified in the Hubble Ultra Deep Field using ultra-deep Hubble Space Telescope (HST) Advanced Camera for Surveys and WFC3/IR images. After carefully matching the different point-spread functions, we obtain color maps and multi-band optical/near-IR photometry (BVizYJH) in concentric annuli, from the smallest resolved radial distance ({approx}1.7 kpc) up to several times the H-band effective radius. We find that the inner regions of these galaxies have redder rest-frame UV-optical colors (U - V, U - B, and B - V) than the outer parts. The slopes of the color gradient have no obvious dependence on the redshift and on the stellar mass of the galaxies. They do mildly depend, however, on the overall dust obscuration (E(B - V)) and rest-frame (U - V) color, with more obscured or redder galaxies having steeper color gradients. The z {approx} 2 color gradients are also steeper than those of local early-type ones. The gradient of a single parameter (age, extinction, or metallicity) cannot fully explain the observed color gradients. Fitting the spatially resolved HST seven-band photometry to stellar population synthesis models, we find that, regardless of assumptions on the metallicity gradient, the redder inner regions of the galaxies have slightly higher dust obscuration than the bluer outer regions, implying that dust partly contributes to the observed color gradients, although the magnitude depends on the assumed extinction law. Due to the age-metallicity degeneracy, the derived age gradient depends on the assumptions for the metallicity gradient. We discuss the implications of a number of assumptions for metallicity gradients on the formation and evolution of these galaxies. We find that the evolution of the mass-size relationship from z {approx} 2 to the present cannot be driven by in situ extended star formation, which implies that accretion or merger is mostly responsible for the growth of their stellar mass and size. The lack of a correlation between the strength of the color gradient and the stellar mass argues against the metallicity gradient predicted by the monolithic-collapse scenario, which would require significant major mergers to evolve into the one observed at the present.

Guo Yicheng; Giavalisco, Mauro; Cassata, Paolo; Salimbeni, Sara [Astronomy Department, University of Massachusetts, 710 N. Pleasant Street, Amherst, MA 01003 (United States); Ferguson, Henry C.; Koekemoer, Anton; Grogin, Norman A.; Lotz, Jennifer M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Dickinson, Mark [NOAO-Tucson, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Renzini, Alvio [INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Papovich, Casey [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics, Texas A and M University, College Station, TX 77843-4242 (United States); Tundo, Elena [INAF-Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste (Italy); Fontana, Adriano, E-mail: yicheng@astro.umass.edu [INAF-Osservatorio Astronomico di Roma, via Frascati 33, Monteporzio-Catone (Roma) I-00040 (Italy)

2011-07-01T23:59:59.000Z

298

Thermodynamics of the Schwarzschild-de Sitter black hole: Thermal stability of the Nariai black hole  

SciTech Connect (OSTI)

We study the thermodynamics of the Schwarzschild-de Sitter black hole in five dimensions by introducing two temperatures based on the standard and Bousso-Hawking normalizations. We use the first-law of thermodynamics to derive thermodynamic quantities. The two temperatures indicate that the Nariai black hole is thermodynamically unstable. However, it seems that black hole thermodynamics favors the standard normalization and does not favor the Bousso-Hawking normalization.

Myung, Yun Soo [Institute of Basic Science and School of Computer Aided Science Inje University, Gimhae 621-749 (Korea, Republic of)

2008-05-15T23:59:59.000Z

299

Thermodynamics of Schwarzschild-de Sitter black hole: thermal stability of Nariai black hole  

E-Print Network [OSTI]

We study thermodynamics of the Schwarzschild-de Sitter black hole in five dimensions by introducing two temperatures based on the standard and Bousso-Hawking normalizations. We use the first-law of thermodynamics to derive thermodynamic quantities. The two temperatures indicate that the Nariai black hole is thermodynamically unstable. However, it seems that black hole thermodynamics favors the standard normalization, and does not favor the Bousso-Hawking normalization.

Yun Soo Myung

2007-12-20T23:59:59.000Z

300

Phase transitions and Geometrothermodynamics of Regular black holes  

E-Print Network [OSTI]

In this paper we study the thermodynamics and state space geometry of regular black hole solutions such as Bardeen black hole, Ay\\'{o}n-Beato and Garc\\'{i}a black hole, Hayward black hole and Berej-Matyjasek-Trynieki-Wornowicz black hole. We find that all these black holes show second order thermodynamic phase transitions(SOTPT) by observing discontinuities in heat capacity-entropy graphs as well as the cusp type double point in free energy-temperature graph. Using the formulation of geometrothermodynamics we again find the singularities in the heat capacity of the black holes by calculating the curvature scalar of the Legendre invariant metric.

R. Tharanath; Jishnu Suresh; V. C. Kuriakose

2014-06-16T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

A planar ion trap chip with integrated structures for an adjustable magnetic field gradient  

E-Print Network [OSTI]

field necessary for magnetic-gradient- induced coupling between ionic effective spins. We dem- onstrate] magnetic field gradient, however, such coupling is induced. Also, coupling between spin states of different-gradient- induced coupling (MAGIC). A static gradient can be generated by permanent mag- nets [15, 16] or by current

Wunderlich, Christof

302

Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence  

SciTech Connect (OSTI)

It is found in collisionless Electron Temperature Gradient (ETG) turbulence simulations that, while zonal flows are weak at early times, the zonal flows continue to grow algebraically (proportional to time). These fine-scale zonal flows have a radial wave number such that kr{rho}i > 1 and kr{rho}e < 1. Eventually, the zonal flows grow to a level that suppresses the turbulence due to ExB shearing. The final electron energy flux is found to be relatively low. These conclusions are based on particle convergence studies with adiabatic ion electrostatic flux-tube gyrokinetic {delta}f particle simulations run for long times. The Rosenbluth-Hinton random walk mechanism is given as an explanation for the long time build up of the zonal flow in ETG turbulence and it is shown that the generation is (k perpendicular {rho}e)2 smaller than for isomorphic Ion Temperature Gradient (ITG) problem. This mechanism for zonal flow generation here is different than the modulational instability mechanism for ITG turbulence. These results are important because previous results indicated zonal flows were unimportant for ETG turbulence. Weak collisional damping of the zonal flow is also shown to be a n important effect.

Parker, S. E.; Kohut, J. J.; Chen, Y. [Center for Integrated Plasma Studies, University of Colorado, Boulder, C0 (United States); Lin, Z. [University of Californian, Irvine, CA (United States); Hinton, F. L. [Hinton Associates, Escondido, CA (United States); Lee, W. W. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)

2006-11-30T23:59:59.000Z

303

Spectral line broadening in magnetized black holes  

E-Print Network [OSTI]

We consider weakly magnetized non-rotating black holes. In the presence of a regular magnetic field the motion of charged particles in the vicinity of a black hole is modified. As a result, the position of the innermost stable circular orbit (ISCO) becomes closer to the horizon. When the Lorentz force is repulsive (directed from the black hole) the ISCO radius can reach the gravitational radius. In the process of accretion charged particles (ions) of the accreting matter can be accumulated near their ISCO, while neutral particles fall down to the black hole after they reach $6M$ radius. The sharp spectral line Fe K$\\alpha$, emitted by iron ions at such orbits, is broadened when the emission is registered by a distant observer. In this paper we study this broadening effect and discuss how one can extract information concerning the strength of the magnetic field from the observed spectrum.

Valeri P. Frolov; Andrey A. Shoom; Christos Tzounis

2014-05-02T23:59:59.000Z

304

Energy of 4-Dimensional Black Hole, etc  

E-Print Network [OSTI]

In this letter I suggest possible redefinition of mass density, not depending on speed of the mass element, which leads to a more simple stress-energy for an object. I calculate energy of black hole.

Dmitriy Palatnik

2011-07-18T23:59:59.000Z

305

Horizon Operator Approach to Black Hole Quantization  

E-Print Network [OSTI]

The $S$-matrix Ansatz for the construction of a quantum theory of black holes is further exploited. We first note that treating the metric tensor $g_{\\m\

G. 't Hooft

1994-02-21T23:59:59.000Z

306

Time Machine at the LHC  

E-Print Network [OSTI]

Recently, black hole and brane production at CERN's Large Hadron Collider (LHC) has been widely discussed. We suggest that there is a possibility to test causality at the LHC. We argue that if the scale of quantum gravity is of the order of few TeVs, proton-proton collisions at the LHC could lead to the formation of time machines (spacetime regions with closed timelike curves) which violate causality. One model for the time machine is a traversable wormhole. We argue that the traversable wormhole production cross section at the LHC is of the same order as the cross section for the black hole production. Traversable wormholes assume violation of the null energy condition (NEC) and an exotic matter similar to the dark energy is required. Decay of the wormholes/time machines and signatures of time machine events at the LHC are discussed.

I. Ya. Aref'eva; I. V. Volovich

2007-10-15T23:59:59.000Z

307

Geology and Temperature Gradient Surveys Blue Mountain Geothermal  

Open Energy Info (EERE)

Geology and Temperature Gradient Surveys Blue Mountain Geothermal Geology and Temperature Gradient Surveys Blue Mountain Geothermal Discovery, Humboldt County, Nevada Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Geology and Temperature Gradient Surveys Blue Mountain Geothermal Discovery, Humboldt County, Nevada Abstract Triassic argillite and sandstone of the Grass Valley Formation and phyllitic mudstone of the overlying Raspberry Formation, also of Triassic age, host a blind geothermal system under exploration by Blue Mountain Power Company Inc. with assistance from the Energy & Geoscience Institute. Geologically young, steeply dipping, open fault sets, striking N50-60°E,N50-60°W, and N-S intersect in the geothermal zone providing deep permeability over a wide area. Extensive silicification andhydro

308

Pumpernickel Valley Geothermal Project Thermal Gradient Wells | Open Energy  

Open Energy Info (EERE)

Valley Geothermal Project Thermal Gradient Wells Valley Geothermal Project Thermal Gradient Wells Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Pumpernickel Valley Geothermal Project Thermal Gradient Wells Details Activities (4) Areas (1) Regions (0) Abstract: The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault,

309

Jordan Algebras and Extremal Black Holes  

E-Print Network [OSTI]

We review various properties of the exceptional Euclidean Jordan algebra of degree three. Euclidean Jordan algebras of degree three and their corresponding Freudenthal triple systems were recently shown to be intimately related to extremal black holes in N=2, d=4 homogeneous supergravities. Using a novel type of eigenvalue problem with eigenmatrix solutions, we elucidate the rich matrix geometry underlying the exceptional N=2, d=4 homogeneous supergravity and explore the relations to extremal black holes.

Michael Rios

2007-03-27T23:59:59.000Z

310

Black hole entropy and higher curvature interactions  

Science Journals Connector (OSTI)

A general formula for the entropy of stationary black holes in Lovelock higher-curvature gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.

Ted Jacobson and Robert C. Myers

1993-06-14T23:59:59.000Z

311

Mutiny at the white-hole district  

E-Print Network [OSTI]

The white-hole sector of Kruskal's solution is almost never used in physical applications. However, it might contain the solution to many of the problems associated with gravitational collapse and evaporation. This essay tries to draw attention to some bouncing geometries that make a democratic use of the black- and white-hole sectors. We will argue that these types of behaviour could be perfectly natural in some approaches to the next physical level beyond classical general relativity.

Carlos Barcel; Ral Carballo-Rubio; Luis J. Garay

2014-07-05T23:59:59.000Z

312

Black hole firewalls, smoke and mirrors  

Science Journals Connector (OSTI)

The radiation emitted by a black hole (BH) during its evaporation has to have some degree of quantum coherence to accommodate a unitary time evolution. We parametrize the degree of coherence by the number of coherently emitted particles Ncoh and show that it is severely constrained by the equivalence principle. We discuss, in this context, the fate of a shell of matter that falls into a Schwarzschild BH. Two points of view are considered: that of a stationary external observer and that of the shell itself. From the perspective of the shell, the near-horizon region has an energy density proportional to Ncoh2 in Schwarzschild units. So, if Ncoh is parametrically larger than the square root of the BH entropy SBH1/2, a firewall or more generally a wall of smoke forms and the equivalence principle is violated while the BH is still semiclassical. To have a degree of coherence that is parametrically smaller than SBH1/2, one has to introduce a new sub-Planckian gravitational length scale, which likely also violates the equivalence principle. And so our previously proposed model which has Ncoh=SBH1/2 is singled out. From the external-observer perspective, we find that the time it takes for the information about the state of the shell to get re-emitted from the BH is inversely proportional to Ncoh. When the rate of information release becomes of order unity, the semiclassical approximation starts to break down and the BH becomes a perfect reflecting information mirror.

Ram Brustein and A.?J.?M. Medved

2014-07-16T23:59:59.000Z

313

Thermodynamics and evaporation of the noncommutative black hole  

E-Print Network [OSTI]

We investigate the thermodynamics of the noncommutative black hole whose static picture is similar to that of the nonsingular black hole known as the de Sitter-Schwarzschild black hole. It turns out that the final remnant of extremal black hole is a thermodynamically stable object. We describe the evaporation process of this black hole by using the noncommutativity-corrected Vaidya metric. It is found that there exists a close relationship between thermodynamic approach and evaporation process.

Yun Soo Myung; Yong-Wan Kim; Young-Jai Park

2006-11-24T23:59:59.000Z

314

Gdel black hole, closed timelike horizon, and the study of particle emissions  

E-Print Network [OSTI]

We show that a particle, with positive orbital angular momentum, following an outgoing null/timelike geodesic, shall never reach the closed timelike horizon (CTH) present in the $(4+1)$-dimensional rotating G\\"{o}del black hole space-time. Therefore a large part of this space-time remains inaccessible to a large class of geodesic observers, depending on the conserved quantities associated with them. We discuss how this fact and the existence of the closed timelike curves present in the asymptotic region make the quantum field theoretic study of the Hawking radiation, where the asymptotic observer states are a pre-requisite, unclear. However, the semiclassical approach provides an alternative to verify the Smarr formula derived recently for the rotating G\\"{o}del black hole. We present a systematic analysis of particle emissions, specifically for scalars, charged Dirac spinors and vectors, from this black hole via the semiclassical complex path method.

Sourav Bhattacharya; Anirban Saha

2010-07-22T23:59:59.000Z

315

Solar Wind Forecasting with Coronal Holes  

E-Print Network [OSTI]

An empirical model for forecasting solar wind speed related geomagnetic events is presented here. The model is based on the estimated location and size of solar coronal holes. This method differs from models that are based on photospheric magnetograms (e.g., Wang-Sheeley model) to estimate the open field line configuration. Rather than requiring the use of a full magnetic synoptic map, the method presented here can be used to forecast solar wind velocities and magnetic polarity from a single coronal hole image, along with a single magnetic full-disk image. The coronal hole parameters used in this study are estimated with Kitt Peak Vacuum Telescope He I 1083 nm spectrograms and photospheric magnetograms. Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated. The new model is found to be accurate to within 10% of observed solar wind measurements for its best one-month periods, and it has a linear correlation coefficient of ~0.38 for the full 11 years studied. Using a single estimated coronal hole map, the model can forecast the Earth directed solar wind velocity up to 8.5 days in advance. In addition, this method can be used with any source of coronal hole area and location data.

S. Robbins; C. J. Henney; J. W. Harvey

2007-01-09T23:59:59.000Z

316

Initial data for black hole evolutions  

E-Print Network [OSTI]

We discuss the initial value problem of general relativity in its recently unified Lagrangian and Hamiltonian pictures and present a multi-domain pseudo-spectral collocation method to solve the resulting coupled nonlinear partial differential equations. Using this code, we explore several approaches to construct initial data sets containing one or two black holes: We compute quasi-circular orbits for spinning equal mass black holes and unequal mass (nonspinning) black holes using the effective potential method with Bowen-York extrinsic curvature. We compare initial data sets resulting from different decompositions, and from different choices of the conformal metric with each other. Furthermore, we use the quasi-equilibrium method to construct initial data for single black holes and for binary black holes in quasi-circular orbits. We investigate these binary black hole data sets and examine the limits of large mass-ratio and wide separation. Finally, we propose a new method for constructing spacetimes with superposed gravitational waves of possibly very large amplitude.

Harald P. Pfeiffer

2005-10-04T23:59:59.000Z

317

Nonlinear elastic free energies and gradient Young-Gibbs measures  

E-Print Network [OSTI]

We investigate, in a fairly general setting, the limit of large volume equilibrium Gibbs measures for elasticity type Hamiltonians with clamped boundary conditions. The existence of a quasiconvex free energy, forming the large deviations rate functional, is shown using a new interpolation lemma for partition functions. The local behaviour of the Gibbs measures can be parametrized by Young measures on the space of gradient Gibbs measures. In view of unboundedness of the state space, the crucial tool here is an exponential tightness estimate that holds for a vast class of potentials and the construction of suitable compact sets of gradient Gibbs measures.

Roman Koteck; Stephan Luckhaus

2012-06-26T23:59:59.000Z

318

Speed-gradient principle for nonstationary processes in thermodynamics  

E-Print Network [OSTI]

The speed-gradient variational principle (SG-principle) is formulated and applied to thermodynamical systems. It is shown that Prigogine's principle of minimum entropy production and Onsager's symmetry relations can be interpreted in terms of the SG-principle and, therefore, are equivalent to each other. In both cases entropy of the system plays a role of the goal functional. The speed-gradient formulation of thermodynamic principles provide their extended versions, describing transient dynamics of nonstationary systems far from equilibrium. As an example a model of transient (relaxation) dynamics for maximum entropy principle is derived.

Alexander L. Fradkov

2007-01-28T23:59:59.000Z

319

Geodesic Structure of the Schwarzschild Black Hole in Rainbow Gravity  

E-Print Network [OSTI]

In this paper we study the geodesic structure of the Schwarzschild black hole in rainbow gravity analyzing the behavior of null and time-like geodesic. We find that the structure of the geodesics essentially does not change when the semi-classical effects are included. However, we can distinguish different scenarios if we take into account the effects of rainbow gravity. Depending on the type of rainbow functions under consideration, inertial and external observers see very different situations in radial and non radial motion of a test particles.

Carlos Leiva; Joel Saavedra; Jose Villanueva

2008-12-09T23:59:59.000Z

320

Kappa - Poincare dispersion relations and the black hole radiation  

E-Print Network [OSTI]

Following the methods developed by Corley and Jacobson, we consider qualitatively the issue of Hawking radiation in the case when the dispersion relation is dictated by quantum kappa-Poincare algebra. This relation corresponds to field equations that are non-local in time, and, depending on the sign of the parameter kappa, to sub- or superluminal signal propagation. We also derive the conserved inner product, that can be used to count modes, and therefore to obtain the spectrum of black hole radiation in this case.

A. Blaut; J. Kowalski-Glikman; D. Nowak-Szczepaniak

2001-08-28T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Control of seeding phase for a cascaded laser wakefield accelerator with gradient injection  

SciTech Connect (OSTI)

We demonstrated experimentally the seeding-phase control for a two-stage laser wakefield accelerator with gradient injection. By optimizing the seeding phase of electrons into the second stage, electron beams beyond 0.5 GeV with a 3% rms energy spread were produced over a short acceleration distance of ?2 mm. Peak energy of the electron beam was further extended beyond 1 GeV by lengthening the second acceleration stage to 5 mm. Time-resolved magnetic field measurements via magneto-optical Faraday polarimetry allowed us to monitor the processes of electron seeding and acceleration in the second stage.

Wang, Wentao; Li, Wentao; Liu, Jiansheng; Wang, Cheng; Chen, Qiang; Zhang, Zhijun; Qi, Rong; Leng, Yuxin; Liang, Xiaoyan; Liu, Yanqi; Lu, Xiaoming; Wang, Cheng; Li, Ruxin; Xu, Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (CAS), Shanghai 201800 (China)] [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (CAS), Shanghai 201800 (China)

2013-12-09T23:59:59.000Z

322

Gradient-Based Distance Estimation for Spatial Computers  

Science Journals Connector (OSTI)

......the reduced width area, the average gradient value Gout avg and the SMG value Gout si are shown using Equation (12) and (13). If...Gin si as shown using Equation (14) and (15). Gout avg = nl (a - 1) + nl a + nl (a + 1) nl = a......

Qingzhi Liu; Andrei Pruteanu; Stefan Dulman

2013-12-01T23:59:59.000Z

323

Oil displacement through a porous medium with a temperature gradient  

E-Print Network [OSTI]

We investigate the effect of a temperature gradient on oil recovery in a two-dimensional pore-network model. The oil viscosity depends on temperature as, $\\mu_o=exp(B/T)$, where $B$ is a physico-chemical parameter depending on the type of oil, and $T$ is the temperature. A temperature gradient is applied across the medium in the flow direction. Initially, the porous medium is saturated with oil and, then, another fluid is injected. We have considered two cases representing different injection strategies. In the first case, the invading fluid viscosity is constant (finite viscosity ratio) while in the second one, the invading fluid is inviscid (infinite viscosity ratio). Our results show that, for the case of finite viscosity ratio, recovery increases with $\\Delta T$ independently on strength or sign of the gradient. For an infinite viscosity ratio, a positive temperature gradient is necessary to enhance recovery. Moreover, we show that, for $\\Delta T>0$, the percentage of oil recovery generally decreases (inc...

Oliveira, C L N; Herrmann, H J

2011-01-01T23:59:59.000Z

324

Finite-Pressure-Gradient Influences on Ideal Spheromak Equilibrium  

Science Journals Connector (OSTI)

Spatially resolved measurements of the magnetic field of a spheromak have been analyzed and compared with expectations for the ratio of j?B from the pressure-gradient-free Taylor model and a model with pressure due to Morikawa. Better agreement is found with the model containing finite pressure.

G. W. Hart; C. Chin-Fatt; A. W. DeSilva; G. C. Goldenbaum; R. Hess; R. S. Shaw

1983-10-24T23:59:59.000Z

325

Simulation of IPA Gradients in Hybrid Network Systems Benjamin Melamed  

E-Print Network [OSTI]

Simulation of IPA Gradients in Hybrid Network Systems Benjamin Melamed Rutgers University Rutgers Atlanta, GA 30332 October 26, 2005 Abstract Infinitesimal Perturbation Analysis (IPA) provides formulas paths of stochastic systems. In practice, IPA derivatives may be computed either from simulation runs

326

Seasonal mass balance gradients in Norway L. A. Rasmussen1  

E-Print Network [OSTI]

Norwegian Water Resources and Energy Directorate (NVE) P. O. Box 5091 Majorstua, N-0301 Oslo, Norway16 Aug 05 Seasonal mass balance gradients in Norway L. A. Rasmussen1 and L. M. Andreassen2 1 in Norway exists in their profiles of both seasonal balances, winter bw(z) and summer bs(z). Unlike many

Rasmussen, L.A.

327

Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient  

E-Print Network [OSTI]

Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient H. L. Schoenfuss ? 2008 ? Springer Science+Business Media, LLC 2008 Abstract Many toxic effects of treated wastewater environment of treated wastewater effluent frequently differs consider- ably from that of its receiving waters

Julius, Matthew L.

328

Three-dimensional radiative properties of hot accretion flows on to the Galactic Centre black hole  

Science Journals Connector (OSTI)

......discs|black hole physics|MHD|plasmas|radiative transfer...inefficient accretion flows modelled by MHD simulations. The synthetic images...baseline-correlated flux density diagram of the recent very-long-baseline...the first time that our 3-D MHD model with differing density......

Y. Kato; M. Umemura; K. Ohsuga

2009-12-21T23:59:59.000Z

329

Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre  

Science Journals Connector (OSTI)

... . The infrared flares all originated from within a few milliarcseconds, or a few hundred Schwarzschild radii, of the black-hole position (Table 1). That position was determined from ... the infrared flares originate in the innermost accretion zone, on a scale less than ten Schwarzschild radii (the light travel time across the ...

R. Genzel; R. Schdel; T. Ott; A. Eckart; T. Alexander; F. Lacombe; D. Rouan; B. Aschenbach

2003-10-30T23:59:59.000Z

330

Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock  

E-Print Network [OSTI]

Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock G. K, University of New Brunswick, Canada M. L. Goldstein NASA Goddard Space Flight Center, Greenbelt, Maryland P that are five or more times the solar wind density. Particle distributions show the steepened edge can behave

California at Berkeley, University of

331

Black Hole Evaporation in an Expanding Universe  

E-Print Network [OSTI]

We calculate the quantum radiation power of black holes which are asymptotic to the Einstein-de Sitter universe at spatial and null infinities. We consider two limiting mass accretion scenarios, no accretion and significant accretion. We find that the radiation power strongly depends on not only the asymptotic condition but also the mass accretion scenario. For the no accretion case, we consider the Einstein-Straus solution, where a black hole of constant mass resides in the dust Friedmann universe. We find negative cosmological correction besides the expected redshift factor. This is given in terms of the cubic root of ratio in size of the black hole to the cosmological horizon, so that it is currently of order $10^{-5} (M/10^{6}M_{\\odot})^{1/3} (t/14 {Gyr})^{-1/3}$ but could have been significant at the formation epoch of primordial black holes. Due to the cosmological effects, this black hole has not settled down to an equilibrium state. This cosmological correction may be interpreted in an analogy with th...

Saida, Hiromi; Maeda, Hideki

2007-01-01T23:59:59.000Z

332

Measuring Hawking Radiation of a Kerr-Newman Black Hole in a Superconducting Transmission Line  

E-Print Network [OSTI]

Applying a dimensional reduction technique and a coordinates transformation approach, we deduce the Kerr-Newman space-time into a Painlev\\'{e}-like form, and obtain its corresponding event horizon and the Hawking radiation temperature. We find that, the event horizon of a Kerr-Newman black hole can be simulated in a superconducting transmission line. Moreover, by running some numerical simulation, we confirm that the Hawking radiation of a Kerr-Newman Black Hole can be experimentally measured in a superconducting transmission line.

X. G. Lan; D. Y. Chen; L. F. Wei

2014-01-15T23:59:59.000Z

333

Large Deviations in Stochastic Heat-Conduction Processes Provide a Gradient-Flow Structure for Heat Conduction  

E-Print Network [OSTI]

We consider three one-dimensional continuous-time Markov processes on a lattice, each of which models the conduction of heat: the family of Brownian Energy Processes with parameter $m$, a Generalized Brownian Energy Process, and the Kipnis-Marchioro-Presutti process. The hydrodynamic limit of each of these three processes is a parabolic equation, the linear heat equation in the case of the BEP$(m)$ and the KMP, and a nonlinear heat equation for the GBEP($a$). We prove the hydrodynamic limit rigorously for the BEP$(m)$, and give a formal derivation for the GBEP($a$). We then formally derive the pathwise large-deviation rate functional for the empirical measure of the three processes. These rate functionals imply gradient-flow structures for the limiting linear and nonlinear heat equations. We contrast these gradient-flow structures with those for processes describing the diffusion of mass, most importantly the class of Wasserstein gradient-flow systems. The linear and nonlinear heat-equation gradient-flow structures are each driven by entropy terms of the form $-\\log \\rho$; they involve dissipation or mobility terms of order $\\rho^2$ for the linear heat equation, and a nonlinear function of $\\rho$ for the nonlinear heat equation.

Mark A. Peletier; Frank Redig; Kiamars Vafayi

2014-03-19T23:59:59.000Z

334

On the nonlinear stability of a quasi-two-dimensional drift kinetic model for ion temperature gradient turbulence  

E-Print Network [OSTI]

We study a quasi-two-dimensional electrostatic drift kinetic system as a model for near-marginal ion temperature gradient (ITG) driven turbulence. A proof is given of the nonlinear stability of this system under conditions of linear stability. This proof is achieved using a transformation that diagonalizes the linear dynamics and also commutes with nonlinear $E\\times B$ advection. For the case when linear instability is present, a corollary is found that forbids nonlinear energy transfer between appropriately defined sets of stable and unstable modes. It is speculated that this may explain the preservation of linear eigenmodes in nonlinear gyrokinetic simulations. Based on this property, a dimensionally reduced ($\\infty\\times\\infty \\rightarrow 1$) system is derived that may be useful for understanding dynamics around the critical gradient of Dimits.

Plunk, G G

2015-01-01T23:59:59.000Z

335

Performance of conjugate gradient-like algorithms in transient two-phase subchannel analysis  

SciTech Connect (OSTI)

A transient, drift-flux subchannel analysis code (SWIRL) has been created for the development and evaluation of algorithms for the solution of weakly three-dimensional fluid flow problems. Spatial discretization on a staggered grid, semi-implicit temporal discretization, and algebraic reduction of the conservation equations of mass, energy, and momentum result in nonsymmetric block-tridiagonal linear systems of equations that must be solved for the pressure distribution at each time step of a transient. The solution of these systems of equations is the most time-consuming portion of the code, and direct, stationary iterative, and preconditioned conjugate gradient (CG)-like methods have been investigated both for a simple approach to steady-state and for a severe transient. The best direct algorithm appears to be an efficient implementation of block elimination, and iterative methods are compared to this algorithm for accuracy, robustness, and efficiency. Results presented here indicate that preconditioned CG-like methods such as Sonneveld's conjugate gradients squared are superior to an efficient direct method. 44 refs., 13 figs.

Turner, J.A. (Los Alamos National Lab., NM (USA)); Doster, M.J. (North Carolina State Univ., Raleigh, NC (USA). Dept. of Nuclear Engineering)

1991-01-01T23:59:59.000Z

336

Injection of Electrons and Holes into Nanostructures  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Injection of Electrons and Holes into Nanostructures Injection of Electrons and Holes into Nanostructures This program targets fundamental understanding of nanoscale charge transfer processes. The proposed work draws on the strengths of the Brookhaven Chemistry Department in the areas of electron transfer experiment and theory, and extends the area of inquiry to nanoscale processes. Electron/hole injection into a wire, a nanocrystal, a nanotube or other nanostructure in solution may be brought about by light absorption, by an electron pulse (pulse radiolysis, LEAF), by a chemical reagent, or through an electrode. These processes are being studied by transient methods by following conductivity, current, but most generally, spectroscopic changes in the solutions to determine the dynamics of charge injection. The observed transient spectra can also provide values for electron-transfer coupling elements and energetics. Theoretical/computational studies can help in materials design and in the interpretation of the experimental results. The experimental systems being examined include molecular wires and metal nanoclusters.

337

Black Hole Complementarity in Gravity's Rainbow  

E-Print Network [OSTI]

We calculate the required energy for duplication of information in the context of black hole complementarity in the rainbow Schwarzschild black hole. The resultant energy can be written as the well-defined limit given by the conventional result for the vanishing rainbow parameter which characterizes the deformation of the relativistic dispersion relation in the freely falling frame. It shows that the duplication of information in quantum mechanics could be not allowed below a certain critical value of the rainbow parameter; however, it could be possible above the critical value of the rainbow parameter, so that the consistent formulation in the rainbow Schwarzschild black hole requires additional constraints or any other resolutions for the latter case.

Gim, Yongwan

2015-01-01T23:59:59.000Z

338

Nonperturbative black hole entropy and Kloosterman sums  

E-Print Network [OSTI]

Non-perturbative quantum corrections to supersymmetric black hole entropy often involve nontrivial number-theoretic phases called Kloosterman sums. We show how these sums can be obtained naturally from the functional integral of supergravity in asymptotically AdS_2 space for a class of black holes. They are essentially topological in origin and correspond to charge-dependent phases arising from the various gauge and gravitational Chern-Simons terms and boundary Wilson lines evaluated on Dehn-filled solid 2-torus. These corrections are essential to obtain an integer from supergravity in agreement with the quantum degeneracies, and reveal an intriguing connection between topology, number theory, and quantum gravity. We give an assessment of the current understanding of quantum entropy of black holes.

Dabholkar, Atish; Murthy, Sameer

2014-01-01T23:59:59.000Z

339

The AGN Black Hole Mass Database  

E-Print Network [OSTI]

The AGN Black Hole Mass Database is a compilation of all published spectroscopic reverberation-mapping studies of active galaxies. We have created a public web interface, where users may get the most up-to-date black hole masses from reverberation mapping for any particular active galactic nucleus (AGN), as well as obtain the individual measurements upon which the masses are based and the appropriate references. While the database currently focuses on the measurements necessary for black hole mass determinations, we also plan to expand it in the future to include additional useful information, such as host-galaxy characteristics. New reverberation mapping results will also be incorporated into the database as they are published in peer-refereed journals.

Bentz, Misty C

2014-01-01T23:59:59.000Z

340

Black hole chromosphere at the CERN LHC  

Science Journals Connector (OSTI)

If the scale of quantum gravity is near a TeV, black holes will be copiously produced at the CERN LHC. In this work we study the main properties of the light descendants of these black holes. We show that the emitted partons are closely spaced outside the horizon, and hence they do not fragment into hadrons in vacuum but more likely into a kind of quark-gluon plasma. Consequently, the thermal emission occurs far from the horizon, at a temperature characteristic of the QCD scale. We analyze the energy spectrum of the particles emerging from the chromosphere, and find that the hard hadronic jets are almost entirely suppressed. They are replaced by an isotropic distribution of soft photons and hadrons, with hundreds of particles in the GeV range. This provides a new distinctive signature for black hole events at LHC.

Luis Anchordoqui and Haim Goldberg

2003-03-26T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Strings as solitons & black holes as strings  

Science Journals Connector (OSTI)

Supersymmetric closed string theories contain an infinite tower of BPS-saturated, oscillating, macroscopic strings in the perturbative spectrum. When these theories have dual formulations, this tower of states must exist nonperturbatively as solitons in the dual theories. We present a general class of exact solutions of low-energy supergravity that corresponds to all these states. After dimensional reduction they can be interpreted as supersymmetric black holes with a degeneracy related to the degeneracy of the string states. For example, in four dimensions we obtain a point-like solution which is asymptotic to a stationary, rotating, electrically-charged black hole with Regge-bounded angular momentum and with the usual ring-singularity replaced by a string source. This further supports the idea that the entropy of supersymmetric black holes can be understood in terms of counting of string states. We also discuss some applications of these solutions to string duality.

Atish Dabholkar; Jerome P. Gauntlett; Jeffrey A. Harvey; Daniel Waldram

1996-01-01T23:59:59.000Z

342

3D SPH Simulations of Shocks in Accretion Flows around black holes  

E-Print Network [OSTI]

We present the simulation of 3D time dependent flow of rotating ideal gas falling into a Schwarzschild black hole. It is shown that also in the 3D case steady shocks are formed in a wide range of parameters (initial angular momentum and thermal energy). We therefore highlight the stability of the phenomenon of shock formation in sub keplerian flows onto black holes, and reenforce the role of the shocks in the high luminosity emission from black hole candidates. The simulations have been performed using a parallelized code based on the Smoothed Particles Hydrodynamics method (SPH). We also discuss some properties of the shock problem that allow its use as a quantitative test of the accuracy of the used numerical method. This shows that the accuracy of SPH is acceptable although not excellent.

G. Gerardi; D. Molteni; V. Teresi

2005-01-25T23:59:59.000Z

343

Seismic gravity-gradient noise in interferometric gravitational-wave detectors  

E-Print Network [OSTI]

When ambient seismic waves pass near an interferometric gravitational-wave detector, they induce density perturbations in the earth which produce fluctuating gravitational forces on the interferometer's test masses. These forces mimic a stochastic background of gravitational waves and thus constitute noise. We compute this noise using the theory of multimode Rayleigh and Love waves propagating in a layered medium that approximates the geological strata at the LIGO sites. We characterize the noise by a transfer function $T(f) \\equiv \\tilde x(f)/\\tilde W(f)$ from the spectrum of direction averaged ground motion $\\tilde W(f)$ to the spectrum of test mass motion $\\tilde x(f) = L\\tilde h(f)$ (where $L$ is the length of the interferometer's arms, and $\\tilde h(f)$ is the spectrum of gravitational-wave noise). This paper's primary foci are (i) a study of how $T(f)$ depends on the various seismic modes; (ii) an attempt to estimate which modes are excited at the LIGO sites at quiet and noisy times; and (iii) a corresponding estimate of the seismic gravity-gradient noise level. At quiet times the noise is below the benchmark noise level of ``advanced LIGO interferometers'' (although not by much near 10 Hz); it may significantly exceed this level at noisy times. The lower edge of our quiet-time noise is a limit beyond which there is little gain from further improvements in vibration isolation and thermal noise, unless one also reduces seismic gravity-gradient noise. Two methods of reduction are discussed: monitoring the earth's density perturbations, computing their gravitational forces, and correcting the data for those forces; and constructing narrow moats around the interferometers' test masses to shield out the fundamental-mode Rayleigh waves, which we suspect dominate at quiet times.

Scott A. Hughes; Kip S. Thorne

1998-06-03T23:59:59.000Z

344

How red is a quantum black hole?  

E-Print Network [OSTI]

Radiating black holes pose a number of puzzles for semiclassical and quantum gravity. These include the transplanckian problem -- the nearly infinite energies of Hawking particles created near the horizon, and the final state of evaporation. A definitive resolution of these questions likely requires robust inputs from quantum gravity. We argue that one such input is a quantum bound on curvature. We show how this leads to an upper limit on the redshift of a Hawking emitted particle, to a maximum temperature for a black hole, and to the prediction of a Planck scale remnant.

Viqar Husain; Oliver Winkler

2005-05-30T23:59:59.000Z

345

The effects of fastener hole defects  

E-Print Network [OSTI]

) August 1991 ABSTRACT The Effects of Fastener Hole Defects. (August 1991) Scot D. Andrews, B. S. , Texas A8rM University Chair of Advisory Committee: Dr. Orden O. Ochoa The influence of drilling-induced defects, such as delamination, on the fatigue... Of Delaminated Zone Elements . . Figure 34. Enlarged View Of Area Near Hole 58 59 61 Page Figure 35. Example Finite Element Mesh Figure 36. Selected Elements For Stress Distribution Graphs . . Figure 37. Example Of o? Stress Distribution For 18 Ply Tape...

Andrews, Scot D.

2012-06-07T23:59:59.000Z

346

CHARYBDIS: A Black Hole Event Generator  

E-Print Network [OSTI]

CHARYBDIS is an event generator which simulates the production and decay of miniature black holes at hadronic colliders as might be possible in certain extra dimension models. It interfaces via the Les Houches accord to general purpose Monte Carlo programs like HERWIG and PYTHIA which then perform the parton evolution and hadronization. The event generator includes the extra-dimensional `grey-body' effects as well as the change in the temperature of the black hole as the decay progresses. Various options for modelling the Planck-scale terminal decay are provided.

C. M. Harris; P. Richardson; B. R. Webber

2003-07-24T23:59:59.000Z

347

BLACK HOLE ENTROPY IN HIGHER CURVATURE GRAVITY  

E-Print Network [OSTI]

We discuss some recent results on black hole thermodynamics within the context of effective gravitational actions including higher-curvature interactions. Wald's derivation of the First Law demonstrates that black hole entropy can always be expressed as a local geometric density integrated over a space-like cross-section of the horizon. In certain cases, it can also be shown that these entropy expressions satisfy a Second Law. One such simple example is considered from the class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar.

TED JACOBSON; GUNGWON KANG; ROBERT C. MYERS

1995-02-27T23:59:59.000Z

348

Quasilocal first law for black hole thermodynamics  

Science Journals Connector (OSTI)

We first show that stationary black holes satisfy an extremely simple quasilocal form of the first law, ?E=?8??A, where the (quasilocal) energy E=A/(8??) and (local) surface gravity ?=1/?, with A the horizon area and ? is a proper length characterizing the distance to the horizon of a preferred family of quasilocal observers suitable for thermodynamical considerations. Our construction is extended to the more general framework of isolated horizons. The local surface gravity is universal. This has important implications for semiclassical considerations of black hole physics as well as for the fundamental quantum description arising in the context of loop quantum gravity.

Ernesto Frodden; Amit Ghosh; Alejandro Perez

2013-06-24T23:59:59.000Z

349

Microhole Coiled Tubing Bottom Hole Assemblies  

SciTech Connect (OSTI)

The original objective of the project, to deliver an integrated 3 1/8-inch diameter Measurement While Drilling (MWD) and Logging While Drilling (LWD) system for drilling small boreholes using coiled tubing drilling, has been achieved. Two prototype systems have been assembled and tested in the lab. One of the systems has been successfully tested downhole in a conventional rotary drilling environment. Development of the 3 1/8-inch system has also lead to development and commercialization of a slightly larger 3.5-inch diameter system. We are presently filling customer orders for the 3.5-inch system while continuing with commercialization of the 3 1/8-inch system. The equipment developed by this project will be offered for sale to multiple service providers around the world, enabling the more rapid expansion of both coiled tubing drilling and conventional small diameter drilling. The project was based on the reuse of existing technology whenever possible in order to minimize development costs, time, and risks. The project was begun initially by Ultima Labs, at the time a small company ({approx}12 employees) which had successfully developed a number of products for larger oil well service companies. In September, 2006, approximately 20 months after inception of the project, Ultima Labs was acquired by Sondex plc, a worldwide manufacturer of downhole instrumentation for cased hole and drilling applications. The acquisition provided access to proven technology for mud pulse telemetry, downhole directional and natural gamma ray measurements, and surface data acquisition and processing, as well as a global sales and support network. The acquisition accelerated commercialization through existing Sondex customers. Customer demand resulted in changes to the product specification to support hotter (150 C) and deeper drilling (20,000 psi pressure) than originally proposed. The Sondex acquisition resulted in some project delays as the resistivity collar was interfaced to a different MWD system and also as the mechanical design was revised for the new pressure requirements. However, the Sondex acquisition has resulted in a more robust system, secure funding for completion of the project, and more rapid commercialization.

Don Macune

2008-06-30T23:59:59.000Z

350

Physics Beyond the Standard Model: Exotic Leptons and Black Holes at Future Colliders  

E-Print Network [OSTI]

The Standard Model of particle physics has been remarkably successful in describing present experimental results. However, it is assumed to be only a low-energy effective theory which will break down at higher energy scales, theoretically motivated to be around 1 TeV. There are a variety of proposed models of new physics beyond the Standard Model, most notably supersymmetric and extra dimension models. New charged and neutral heavy leptons are a feature of a number of theories of new physics, including the `intermediate scale' class of supersymmetric models. Using a time-of-flight technique to detect the charged leptons at the Large Hadron Collider, the discovery range (in the particular scenario studied in the first part of this thesis) is found to extend up to masses of 950 GeV. Extra dimension models, particularly those with large extra dimensions, allow the possible experimental production of black holes. The remainder of the thesis describes some theoretical results and computational tools necessary to model the production and decay of these miniature black holes at future particle colliders. The grey-body factors which describe the Hawking radiation emitted by higher-dimensional black holes are calculated numerically for the first time and then incorporated in a Monte Carlo black hole event generator; this can be used to model black hole production and decay at next-generation colliders. It is hoped that this generator will allow more detailed examination of black hole signatures and help to devise a method for extracting the number of extra dimensions present in nature.

Christopher M. Harris

2005-02-01T23:59:59.000Z

351

Elastic Relaxation and Correlation of Local Strain Gradients with  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Elastic Relaxation and Correlation Elastic Relaxation and Correlation of Local Strain Gradients with Ferroelectric Domains in (001) BiFeO3 Nanostructures Elastic Relaxation and Correlation of Local Strain Gradients with Ferroelectric Domains in (001) BiFeO3 Nanostructures Researchers at Argonne National Laboratory (MSD and CNM) have recently performed first worldwide studies of effects of nanopatterning on fundamental phenomena in mutiferroic BiFeO3 (BFO) nanostructures, using the APS-CNM nanoprobe beam (50 nm diameter). Nano-focused x-ray diffraction microscopy provided new insights into the relationship between film strain and ferroelectric domains in nanostructures, namely: i) an out-of-plane strain enhancement of as much as -1.8% Δc/c in a BFO film-based nanostructure relative to a planar film; ii) out-of-plane BFO C-axis

352

Gradient Plasticity Model and its Implementation into MARMOT  

SciTech Connect (OSTI)

The influence of strain gradient on deformation behavior of nuclear structural materials, such as boby centered cubic (bcc) iron alloys has been investigated. We have developed and implemented a dislocation based strain gradient crystal plasticity material model. A mesoscale crystal plasticity model for inelastic deformation of metallic material, bcc steel, has been developed and implemented numerically. Continuum Dislocation Dynamics (CDD) with a novel constitutive law based on dislocation density evolution mechanisms was developed to investigate the deformation behaviors of single crystals, as well as polycrystalline materials by coupling CDD and crystal plasticity (CP). The dislocation density evolution law in this model is mechanism-based, with parameters measured from experiments or simulated with lower-length scale models, not an empirical law with parameters back-fitted from the flow curves.

Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin

2013-08-01T23:59:59.000Z

353

Steady and unsteady calibration of multi-hole probes  

E-Print Network [OSTI]

This thesis presents the development of a data crographics. reduction algorithm for multi-hole pressure probes. The algorithm has been developed for the reduction of calibration data from miniature non-nulling multi-hole probes in compressible...

Johansen, Espen S

1998-01-01T23:59:59.000Z

354

Chapter 3 Topology and Uniqueness of Higher Dimensional Black Holes  

Science Journals Connector (OSTI)

......of Particle and Nuclear Studies, High Energy Accelerator Research Organization...asymptotically flat vacuum black holes in...of Particle and Nuclear Studies, High Energy Accelerator Research Organization...asymptotically flat vacuum black holes in......

Daisuke Ida; Akihiro Ishibashi; Tetsuya Shiromizu

2011-06-01T23:59:59.000Z

355

Moving Mirrors, Black Holes, Hawking Radiation and All That  

E-Print Network [OSTI]

In this talk I show how to canonically quantize a massless scalar field in the background of a Schwarzschild black hole in Lema\\^itre coordinates and then present a simplified derivation of Hawking radiation based upon this procedure. The key result of quantization procedure is that the Hamiltonian of the system is explicitly time dependent and so problem is intrinsically non-static. From this it follows that, although a unitary time-development operator exists, it is not useful to talk about vacuum states; rather, one should focus attention on steady state phenomena such as the Hawking radiation. In order to clarify the approximations used to study this problem I begin by discussing the related problem of the massless scalar field theory calculated in the presence of a moving mirror.

Marvin Weinstein

2001-11-09T23:59:59.000Z

356

Moving Mirrors, Black Holes, Hawking Radiation and All That  

E-Print Network [OSTI]

In this talk I show how to canonically quantize a massless scalar field in the background of a Schwarzschild black hole in Lema\\^itre coordinates and then present a simplified derivation of Hawking radiation based upon this procedure. The key result of quantization procedure is that the Hamiltonian of the system is explicitly time dependent and so problem is intrinsically non-static. From this it follows that, although a unitary time-development operator exists, it is not useful to talk about vacuum states; rather, one should focus attention on steady state phenomena such as the Hawking radiation. In order to clarify the approximations used to study this problem I begin by discussing the related problem of the massless scalar field theory calculated in the presence of a moving mirror.

Weinstein, M A

2002-01-01T23:59:59.000Z

357

Moving Mirrors, Black Holes, Hawking Radiation and All That  

SciTech Connect (OSTI)

In this talk I show how, in Lemaitre coordinates, one can canonically quantize a massless scalar field in the background of a Schwarzschild black hole and then show how this leads to a simplified derivation of Hawking radiation. The key result of the canonical quantization procedure is that the Hamiltonian of the system is explicitly time dependent, which immediately shows that the problem is intrinsically non-static and that, although a unitary time-development operator exists, it is not useful to talk about eigenstates. Rather, one should deal with the Heisenberg equations of motion and focus attention on steady state phenomena, such as the Hawking radiation. In order to clarify the procedure used to solve the Heisenberg equations I first discuss the related problem of the massless scalar field theory calculated in the presence of a moving mirror.

Weinstein, Marvin

2001-11-08T23:59:59.000Z

358

Gradient instabilities of electromagnetic waves in Hall thruster plasma  

SciTech Connect (OSTI)

This paper presents a linear analysis of gradient plasma instabilities in Hall thrusters. The study obtains and analyzes the dispersion equation of high-frequency electromagnetic waves based on the two-fluid model of a cold plasma. The regions of parameters corresponding to unstable high frequency modes are determined and the dependence of the increments and intrinsic frequencies on plasma parameters is obtained. The obtained results agree with those of previously published studies.

Tomilin, Dmitry [Department of Electrophysics, Keldysh Research Centre, Moscow 125438 (Russian Federation)

2013-04-15T23:59:59.000Z

359

Bioaccumulation of Perfluorochemicals in Pacific Oyster under Different Salinity Gradients  

Science Journals Connector (OSTI)

Bioaccumulation of Perfluorochemicals in Pacific Oyster under Different Salinity Gradients ... Where Kdsw and Kd0 represent the distribution coefficients in saline and pure water, respectively, S is salinity and kads is a constant for sorption salting constant (?kads = 0.0352?). ... Based on the fact that biotransformation of PFCs is negligible (35), the faster depuration rate for PFCs at higher salinities is attributable to increases in the uptake volume of water associated with increased salinity. ...

Junho Jeon; Kurunthachalam Kannan; Han Kyu Lim; Hyo Bang Moon; Jin Sung Ra; Sang Don Kim

2010-03-15T23:59:59.000Z

360

Determination of dispersivities from a natural-gradient dispersion test  

E-Print Network [OSTI]

, and radioactive wastes. Contaminant hydrogeology is presently a focal point in the realm of hydrologic modeling. Generally, models are designed to represent simplified versions of reality and The style and format of this document was taken from the Journal... dispersivities, v ia a graphical approach, from a natural-gradient dispersion test in which artificial pollution was injected into an aquifer. The dispersion test was conducted by Sud icky et al. (1983) in order to characterize the dispersive properties...

Hoover, Caroline Marie

1985-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Histogram of gradients of Time-Frequency Representations for Audio Scene Detection  

E-Print Network [OSTI]

is of primary importance in the domain of machine listening since it is strongly related to the context in which the acquisition device capturing the audio scene lives. Typically, in order to get some context awareness, a machine, say a smart-phone or any mobile electronic device, should be able to predict the environment

Paris-Sud XI, Université de

362

Histogram of Gradients of Time-Frequency Representations for Audio Scene Detection  

E-Print Network [OSTI]

is of primary importance in the domain of machine listening since it is strongly related to the context in which the acquisition device capturing the audio scene lives. Typically, in order to get some context awareness, a machine, say a smart-phone or any mobile electronic device, should be able to predict the environment

Paris-Sud XI, Université de

363

Diffusion coefficient and radial gradient of galactic cosmic rays  

E-Print Network [OSTI]

We present the temporal changes of the diffusion coefficient K of galactic cosmic rays (GCRs) at the Earth orbit calculated based on the experimental data using two different methods. The first approach is based on the Parker convection-diffusion approximation of GCR modulation [1]: i.e. K~Vr=dI where dI is the variation of the GCR intensity measured by neutron monitors (NM),V is the solar wind velocity and r is the radial distance. The second approach is based on the interplanetary magnetic field (IMF) data. It was suggested that parallel mean free path can be expressed in terms of B as in [2]-[4]. Using data of the product of the parallel mean free path and radial gradient of GCR calculated based on the GCR anisotropy data (Ahluwalia et al., this conference ICRC 2013, poster ID: 487 [5]), we estimate the temporal changes of the radial gradient of GCR at the Earth orbit. We show that the radial gradient exhibits a strong solar cycle dependence (11-year variation) and a weak solar magnetic cycle dependence (2...

Modzelewska, Renata

2015-01-01T23:59:59.000Z

364

Principal processes within the estuarine salinity gradient: A review  

Science Journals Connector (OSTI)

The salinity gradient is one of the main features characteristic of any estuarine ecosystem. Within this gradient in a critical salinity range of 58 PSU the major biotic and abiotic processes demonstrate non-linear dynamics of change in rates and directions. In estuaries, this salinity range acts as both external ecological factor and physiological characteristics of internal environment of aquatic organisms; it divides living conditions appropriate for freshwater and marine faunas, separates invertebrate communities with different osmotic regulation types, and defines the distribution range of high taxa. In this paper, the non-linearity of biotic processes within the estuarine salinity gradient is illustrated by the data on zooplankton from the Baltic estuaries. The non-tidal Baltic Sea provides a good demonstration of the above phenomena due to gradual changes of environmental factors and relatively stable isohalines. The non-linearity concept coupled with the ecosystem approach served the basis for a new definition of an estuary proposed by the authors.

Irena V. Telesh; Vladislav V. Khlebovich

2010-01-01T23:59:59.000Z

365

Considerations of ion-temperature-gradient-driven turbulence  

SciTech Connect (OSTI)

The ion-temperature-gradient-driven instability is considered in this paper. Physical pictures are presented to clarify the nature of the instability. The saturation of a single eddy is modeled by a simple nonlinear equation. It is shown that eddies that are elongated in the direction of the temperature gradient are the most unstable and have the highest saturation amplitudes. In a sheared magnetic field, such elongated eddies twist with the field lines. This structure is shown to be an alternative to the usual Fourier mode picture in which the mode is localized around the surface where {ital k}{sub {parallel}} =0. These elongated twisting eddies, which are an integral part of the ballooning mode'' structure, could survive in a torus. The elongated eddies are shown to be unstable to secondary instabilities that are driven by the large gradients in the long eddy. It is argued that the mixing length'' is affected by this nonlinear process, and is unlikely to be a linear eigenmode width.

Cowley, S.C.; Kulsrud, R.M. (Princeton Plasma Physics Laboratory, Princeton, New Jersey (USA)); Sudan, R. (Cornell University, Ithaca, New York (USA))

1991-10-01T23:59:59.000Z

366

Thought Experiment to resolve the Black Hole Information Paradox  

E-Print Network [OSTI]

We propose a combination of two mechanisms that can resolve the black hole information paradox. The first process is that the black hole shrinks by a first order transition, since we assume the entropy is discontinuous. The black hole disappears. The second type of processes conserves unitarity. We assume that within the black hole micro-reversible quantum mechanical processes take place. These are ordinary particle processes, e.g. the decay of an electron and a positron into two photons.

Kay zum Felde

2014-07-22T23:59:59.000Z

367

Particles and scalar waves in noncommutative charged black hole spacetime  

E-Print Network [OSTI]

In this paper we have discussed geodesics and the motion of test particle in the gravitational field of noncommutative charged black hole spacetime. The motion of massive and massless particle have been discussed seperately. A comparative study of noncommutative charged black hole and usual Reissner-Nordstrom black hole has been done. The study of effective potential has also been included. Finally, we have examined the scattering of scalar waves in noncommutative charged black hole spacetime.

Bhar, Piyali; Biswas, Ritabrata; Mondal, U F

2015-01-01T23:59:59.000Z

368

Ciliate diversity and distribution across an environmental and depth gradient in Long Island  

E-Print Network [OSTI]

Ciliate diversity and distribution across an environmental and depth gradient in Long Island Sound- trichia (Spirotrichea) and Choreotrichia (Spirotrichea) across an environmental gradient. We assessed SSU- tion showed any clear relationship to measured environmental parameters (temperature, salinity

Katz, Laura

369

Virioplankton community structure along a salinity gradient in a solar saltern  

Science Journals Connector (OSTI)

The virioplankton community structure along a salinity gradient from near seawater (40) to saturated ... . The viral community structure changed along the salinity gradient. Cluster analysis of the viral genome-...

Ruth-Anne Sandaa; Evy Foss Skjoldal; Gunnar Bratbak

2003-10-01T23:59:59.000Z

370

High-Performance Ionic Diode Membrane for Salinity Gradient Power Generation  

Science Journals Connector (OSTI)

High-Performance Ionic Diode Membrane for Salinity Gradient Power Generation ... These processes can also capture energy from waste heat by generating artificial salinity gradients using synthetic solns., such as thermolytic salts. ... saline brines because of the higher power d. ...

Jun Gao; Wei Guo; Dan Feng; Huanting Wang; Dongyuan Zhao; Lei Jiang

2014-08-19T23:59:59.000Z

371

Creation of nonlinear density gradients for use in internal wave research  

E-Print Network [OSTI]

A method was developed to create a nonlinear density gradient in a tank of water. Such gradients are useful for studying internal waves, an ocean phenomenon that plays an important role in climate and ocean circulation. ...

Harris, Victoria Sin

2007-01-01T23:59:59.000Z

372

Two black hole initial data  

E-Print Network [OSTI]

Misner initial data are a standard example of time-symmetric initial data with two apparent horizons. Compact formulae describing such data are presented in the cases of equal or non-equal masses (i.e. isometric or non-isometric horizons). The interaction energy in the "Schwarzschild + test particle" limit of the Misner data is analyzed.

Szymon Leski

2005-02-21T23:59:59.000Z

373

The third law of thermodynamics for Kerr black holes  

Science Journals Connector (OSTI)

......research-article Articles The third law of thermodynamics for Kerr black holes Isao...condition under which the third law of black-hole thermodynamics for Kerr holes is not violated...diverge to infinity as a power law for , and therefore no Kerr......

Isao Okamoto; Osamu Kaburaki

1991-05-15T23:59:59.000Z

374

E-Print Network 3.0 - alpine elevation gradient Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ecosystems, generated only by a water availability gradient, the ... Source: Colorado at Boulder, University of - Alpine Microbial Observatory Collection: Environmental...

375

Dielectric-Loaded Microwave Cavity for High-Gradient Testing of Superconducting Materials  

E-Print Network [OSTI]

an energy distribution. Data was taken from the CRC Handbook 90th edition [13]. : : : : : : : : : : : : : : : : : : : : 17 10 Current state of high gradient cavities in the SRF world. Note these points are champion cavities, the average gradient of all... an energy distribution. Data was taken from the CRC Handbook 90th edition [13]. : : : : : : : : : : : : : : : : : : : : 17 10 Current state of high gradient cavities in the SRF world. Note these points are champion cavities, the average gradient of all...

Pogue, Nathaniel Johnston

2011-08-08T23:59:59.000Z

376

E-Print Network 3.0 - african latitudinal gradient Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

richness... latitudinal gradients. Keywords Fleas, geographic range, ... Source: Poulin, Robert - Department of Zoology, University of Otago Collection: Biology and Medicine...

377

Geodesic study of a charged black hole  

E-Print Network [OSTI]

The behavior of the timelike and null geodesics of charged E. Ay$\\acute{o}$n-Beato and A. Garcia (ABG) black hole are investigated. For circular and radial geodesics, we investigate all the possible motions by plotting the effective potentials for different parameters. In conclusion, we have shown that there is no phenomenon of \\textit{superradiance} in this case.

Mehedi Kalam; Nur Farhad; Sk. Monowar Hossein

2013-03-17T23:59:59.000Z

378

Black Holes and Sub-millimeter Dimensions  

E-Print Network [OSTI]

Recently, a new framework for solving the hierarchy problem was proposed which does not rely on low energy supersymmetry or technicolor. The fundamental Planck mass is at a TeV and the observed weakness of gravity at long distances is due the existence of new sub-millimeter spatial dimensions. In this letter, we study how the properties of black holes are altered in these theories. Small black holes---with Schwarzschild radii smaller than the size of the new spatial dimensions---are quite different. They are bigger, colder, and longer-lived than a usual $(3+1)$-dimensional black hole of the same mass. Furthermore, they primarily decay into harmless bulk graviton modes rather than standard-model degrees of freedom. We discuss the interplay of our scenario with the holographic principle. Our results also have implications for the bounds on the spectrum of primordial black holes (PBHs) derived from the photo-dissociation of primordial nucleosynthesis products, distortion of the diffuse gamma-ray spectrum, overcl...

Argyres, Philip C; March-Russell, John David; Argyres, Philip C.; Dimopoulos, Savas; March-Russell, John

1998-01-01T23:59:59.000Z

379

Retarded cores, black holes and galaxy formation  

Science Journals Connector (OSTI)

... It seems likely that elliptical galaxies contain massive 'black holes'?objects collapsed within their Schwarzschild radii?in their nuclei (see, for example, Wolfe and Burbidge2). The principal ... seems to be required to power the observed phenomena. For such a mass, the Schwarzschild radius (R s) is about 10?4 pc; for a mass of 1011 ...

John Gribbin

1974-12-06T23:59:59.000Z

380

Supermassive Black Hole Binaries: The Search Continues  

E-Print Network [OSTI]

Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.

Tamara Bogdanovic

2014-06-19T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Chapter 8 Black Holes in Braneworld Models  

Science Journals Connector (OSTI)

......to the four-dimensional Schwarzschild solution, there is no room...deformed from an ordinary Schwarzschild black hole and the radiation...gravitational attraction from its mirror image on the other side of...The attraction from the mirror image will not be larger than......

Norihiro Tanahashi; Takahiro Tanaka

2011-06-01T23:59:59.000Z

382

Black Holes in 4 Nearby Radio Galaxies  

E-Print Network [OSTI]

We study the velocity dispersion profiles of the nuclei of NGC 1326, 2685, 5273 and 5838 in the CO first overtone band. There is evidence for a black hole (BH) in NGC 1326 and 5838. Gas is seen flowing out of the nuclear region of NGC 5273. We put upper limits on the nuclear BHs responsible for its activity and that of NGC 2685.

Mould, Jeremy; Cotter, Garret; Batt, David; Durre', Mark

2014-01-01T23:59:59.000Z

383

Remote down-hole well telemetry  

DOE Patents [OSTI]

The present invention includes an apparatus and method for telemetry communication with oil-well monitoring and recording instruments located in the vicinity of the bottom of gas or oil recovery pipes. Such instruments are currently monitored using electrical cabling that is inserted into the pipes; cabling has a short life in this environment, and requires periodic replacement with the concomitant, costly shutdown of the well. Modulated reflectance, a wireless communication method that does not require signal transmission power from the telemetry package will provide a long-lived and reliable way to monitor down-hole conditions. Normal wireless technology is not practical since batteries and capacitors have to frequently be replaced or recharged, again with the well being removed from service. RF energy generated above ground can also be received, converted and stored down-hole without the use of wires, for actuating down-hole valves, as one example. Although modulated reflectance reduces or eliminates the loss of energy at the sensor package because energy is not consumed, during the transmission process, additional stored extra energy down-hole is needed.

Briles, Scott D. (Los Alamos, NM); Neagley, Daniel L. (Albuquerque, NM); Coates, Don M. (Santa Fe, NM); Freund, Samuel M. (Los Alamos, NM)

2004-07-20T23:59:59.000Z

384

Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea  

E-Print Network [OSTI]

Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea Michael L. Zettler Biotic Index) and BQI (Benthic Quality Index), were tested along a salinity gradient in the southern; Ecological quality; Salinity gradient; Water Framework Directive; Oxygen depletion 1. Introduction

Zettler, Michael

385

Thin-Film Composite Pressure Retarded Osmosis Membranes for Sustainable Power Generation from Salinity Gradients  

Science Journals Connector (OSTI)

Thin-Film Composite Pressure Retarded Osmosis Membranes for Sustainable Power Generation from Salinity Gradients ... Pressure retarded osmosis has the potential to produce renewable energy from natural salinity gradients. ... Pressure retarded osmosis (PRO) and reverse electrodialysis (RED) are emerging membrane-based technologies that can convert chemical energy in salinity gradients to useful work. ...

Ngai Yin Yip; Alberto Tiraferri; William A. Phillip; Jessica D. Schiffman; Laura A. Hoover; Yu Chang Kim; Menachem Elimelech

2011-04-14T23:59:59.000Z

386

Long-term ecological dynamics: reciprocal insights from natural and anthropogenic gradients  

Science Journals Connector (OSTI)

...be studied by using natural springs that create gradients of CO2 gas, and which are at...gradients There are many natural gradients of climate...adjacent areas in natural forests in Hawaii...such as how trophic cascades and other community...

2005-01-01T23:59:59.000Z

387

Adaptive Restart for Accelerated Gradient Schemes Brendan O'Donoghue Emmanuel Cand`es  

E-Print Network [OSTI]

Adaptive Restart for Accelerated Gradient Schemes Brendan O'Donoghue Emmanuel Cand`es April 13- matically improve the convergence rate of accelerated gradient schemes. The analysis of the technique relies. In what we refer to as the `high momentum' regime the iterates generated by an accelerated gradient scheme

Candes, Emmanuel J.

388

Kinematics of geodesic flows in stringy black hole backgrounds  

E-Print Network [OSTI]

We study the kinematics of timelike geodesic congruences in two and four dimensions in spacetime geometries representing stringy black holes. The Raychaudhuri equations for the kinematical quantities (namely, expansion, shear and rotation) characterising such geodesic flows are written down and subsequently solved analytically (in two dimensions) and numerically (in four dimensions) for specific geodesics flows. We compare between geodesic flows in dual (electric and magnetic) stringy black hole backgrounds in four dimensions, by showing the differences that arise in the corresponding evolutions of the kinematic variables. The crucial role of initial conditions and the spacetime curvature on the evolution of the kinematical variables is illustrated. Some novel general conclusions on geodesic focusing are obtained from the analytical and numerical findings. We also propose new quantifiers in terms of (a) the time (affine parameter) of approach to a singularity and (b) the location of extrema in the functional evolution of the kinematic variables, which may be used to distinguish between flows in different geometries. In summary, our quantitative findings bring out hitherto unknown features of the kinematics of geodesic flows, which, otherwise, would have remained overlooked, if we confined ourselves to only a qualitative analysis.

Anirvan Dasgupta; Hemwati Nandan; Sayan Kar

2009-06-12T23:59:59.000Z

389

Tidal Capture of Stars by Intermediate-Mass Black Holes  

E-Print Network [OSTI]

Recent X-ray observations and theoretical modelling have made it plausible that some ultraluminous X-ray sources (ULX) are powered by intermediate-mass black holes (IMBHs). N-body simulations have also shown that runaway merging of stars in dense star clusters is a way to form IMBHs. In the present paper we have performed N-body simulations of young clusters such as MGG-11 of M82 in which IMBHs form through runaway merging. We took into account the effect of tidal heating of stars by the IMBH to study the tidal capture and disruption of stars by IMBHs. Our results show that the IMBHs have a high chance of capturing stars through tidal heating within a few core relaxation times and we find that 1/3 of all runs contain a ULX within the age limits of MGG-11, a result consistent with the fact that a ULX is found in this galaxy. Our results strengthen the case for some ULX being powered by intermediate-mass black holes.

H. Baumgardt; C. Hopman; S. Portegies Zwart; J. Makino

2005-11-27T23:59:59.000Z

390

Feedback-regulated Super Massive Black Hole Seed Formation  

E-Print Network [OSTI]

The nature of the seeds of high-redshift supermassive black holes (SMBHs) is a key question in cosmology. Direct collapse black holes (DCBH) that form in pristine, atomic-line cooling halos, illuminated by a Lyman-Werner (LW) UV flux exceeding a critical threshold J_crit, represent an attractive possibility. We investigate when and where these conditions are met during cosmic evolution. For the LW intensity, J_LW, we account for departures from the background value in close proximity to star forming galaxies. For the pristine halo fraction, we account for both (i) supernova driven outflows, and (ii) the inherent pollution from progenitor halos. We estimate the abundance of DCBH formation sites, n_DCBH(z), and find that it increases with cosmic time from n_DCBH(z=20) ~ 1e-12 -1e-7 cMpc^-3 to n_DCBH(z=10) ~ 1e-10 - 1e-5 cMpc^-3. Our analysis shows the possible importance of galactic winds, which can suppress the predicted n_DCBH by several orders of magnitude, and cause DCBH formation to preferentially occur ar...

Dijkstra, Mark; Mesinger, Andrei

2014-01-01T23:59:59.000Z

391

Atom interferometric techniques for measuring gravitational acceleration and constant magnetic field gradients  

E-Print Network [OSTI]

We discuss two techniques for probing the effects of a homogeneous force acting on cold atoms, such as that due to gravity or a constant magnetic field gradient, using grating echo-type atom interferometers. A comprehensive theoretical description of signals generated by both two-pulse and three-pulse interferometers, accounting for magnetic sub-levels in the atomic ground state, is shown to agree with experimental results. Laser-cooled samples of $^{85}$Rb with temperatures as low as 2.4 $\\mu$K have been achieved in a relatively large glass cell with well-suppressed magnetic fields. Using transit time limited interferometer signals, we demonstrate sensitivity to externally applied magnetic gradients as small as $\\sim 4$ mG/cm. With these timescales we estimate that precision measurements of the gravitational acceleration, $g$, are possible with both the two-pulse and three-pulse echo interferometers. Whereas the two-pulse signal is a position-sensitive technique to measure the absolute value of $g$, the thre...

Barrett, B

2011-01-01T23:59:59.000Z

392

Kinetic Effects on Turbulence Driven by the Magnetorotational Instability in Black Hole Accretion  

E-Print Network [OSTI]

Magnetorotational Instability (MRI), the instability causing turbulent transport in accretion disks, is studied in the kinetic regime. Radiatively Inefficient Accretion Flows (RIAFs), like the one around the supermassive black hole in the center of our Galaxy, are believed to be collisionless. Kinetic MHD formalism, based on the moments of the Vlasov equation, is used for linear analysis and nonlinear simulations. ZEUS MHD code is modified to include key kinetic MHD terms: anisotropic pressure tensor and anisotropic thermal conduction. Simulations use the local shearing box approximation. Pressure anisotropy is created, because of the adiabatic invariance ($\\mu=p_\\perp/B$), as magnetic field is amplified by the MRI. Larmor radius scale instabilities--mirror, ion-cyclotron, and firehose--are excited at large pressure anisotropy. Pressure isotropization due to pitch angle scattering by these instabilities is included as a subgrid model. A key result of the kinetic MHD simulations is that the anisotropic (viscous) stress can be as large as the Maxwell stress. A new numerical method to simulate anisotropic thermal conduction with large temperature gradients is suggested. Simple tests show that the centered differencing of anisotropic thermal conduction can result in heat flowing from lower to higher temperatures, giving rise to negative temperatures. Limiting of transverse temperature gradients does not accentuate temperature extrema.

Prateek Sharma

2007-03-20T23:59:59.000Z

393

Abundance and diversity of tidal marsh plants along the salinity gradient of the San Francisco Estuary: implications for global change ecology  

E-Print Network [OSTI]

plants along the salinity gradient of the San Franciscotransects along the salinity gradient of the San Franciscoacross the full salinity gradient of the San Francisco

Watson, Elizabeth Burke; Byrne, Roger

2009-01-01T23:59:59.000Z

394

Nonphotochemical hole burning of organic dyes and rare earth ions in polymers and glasses: a probe of the amorphous state  

SciTech Connect (OSTI)

New and in depth studies of amorphous materials (e.g., glasses and polymers) probed via the low temperature optical technique of nonphotochemical hole burning (NPHB) are presented. An extensive review of the phenomena itself, along with selected topics involving the use of persistent hole burning techniques, is given. In addition, a semi-complete tabulation of essentially all hole burning systems to date is included. The deuteration dependence in an amorphous host is examined for the system of tetracene in an ethanol/methanol mixture. The results illustrate the importance of hydrogen bonding in the hole burning process. The discovery of a highly efficient (or facile) class of hole burning systems, i.e., ionic dyes in hydroxylated polymers (i.e., poly(vinyl alcohol) (PVOH) and poly(acrylic acid) (PAA)), is presented and discussed. Ultrafast relaxation processes (i.e., dephasing) are studied for the system of cresyl violet perchlorate (CV) in PVOH. Further, for the first time, NPHB of rare earth ions, specifically Pr/sup +3/ and Nd/sup +3/, in a soft organic glass (i.e., PVOH) is discussed briefly. Detailed experimental results of two related phenomena, spontaneous hole filling (SPHF) and laser induced hole filling (LIHF), are presented and discussed for several systems: rhodamine 560 perchlorate (R560), rhodamine 640 perchlorate (R640), CV, Pr/sup +3/ and Nd..mu../sup 3/ in either PVOH or PAA. A theoretical model is developed for SPHF. The model invokes a correlated feedback mechanism from the anti-hole, which is able to account for the fact that no line broadening is observed. A tentative model is also presented for the phenomenon of LIHF.

Fearey, B.L.

1986-01-01T23:59:59.000Z

395

Fabrication of high gradient insulators by stack compression  

DOE Patents [OSTI]

Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.

Harris, John Richardson; Sanders, Dave; Hawkins, Steven Anthony; Norona, Marcelo

2014-04-29T23:59:59.000Z

396

The gradient flow running coupling with twisted boundary conditions  

E-Print Network [OSTI]

We study the gradient flow for Yang-Mills theories with twisted boundary conditions. The perturbative behavior of the energy density $\\langle E(t)\\rangle$ is used to define a running coupling at a scale given by the linear size of the finite volume box. We compute the non-perturbative running of the pure gauge $SU(2)$ coupling constant and conclude that the technique is well suited for further applications due to the relatively mild cutoff effects of the step scaling function and the high numerical precision that can be achieved in lattice simulations. We also comment on the inclusion of matter fields.

A. Ramos

2014-09-04T23:59:59.000Z

397

High and ulta-high gradient quadrupole magnets  

SciTech Connect (OSTI)

Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e/sup +//e/sup -/ super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%.

Brunk, W.O.; Walz, D.R.

1985-05-01T23:59:59.000Z

398

Superconducting travelling wave ring with high gradient accelerating section  

SciTech Connect (OSTI)

Use of a superconducting traveling wave accelerating (STWA) structure instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting traveling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control traveling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.

Avrakhov, P.; Solyak, N.; /Fermilab

2007-06-01T23:59:59.000Z

399

Gradient index liquid crystal devices and method of fabrication thereof  

DOE Patents [OSTI]

Laser beam apodizers using cholesteric liquid crystals provides soft edge profile by use of two separate cholesteric liquid crystal mixtures with different selective reflection bands which in an overlap region have a gradient index where reflectivity changes as a function of position. The apodizers can be configured as a one-dimensional beam apod INTRODUCTION The U.S. government has rights in the invention under Contract No. DE-FC03-85DP40200 between the University of Rochester and the Department of Energy.

Lee, J.C.; Jacobs, S.

1991-10-29T23:59:59.000Z

400

Laser stabilization using spectral hole burning  

E-Print Network [OSTI]

We have frequency stabilized a Coherent CR699-21 dye laser to a transient spectral hole on the 606 nm transition in Pr^{+3}:Y_2SiO_5. A frequency stability of 1 kHz has been obtained on the 10 microsecond timescale together with a long-term frequency drift below 1 kHz/s. RF magnetic fields are used to repopulate the hyperfine levels allowing us to control the dynamics of the spectral hole. A detailed theory of the atomic response to laser frequency errors has been developed which allows us to design and optimize the laser stabilization feedback loop, and specifically we give a stability criterion that must be fulfilled in order to obtain very low drift rates. The laser stability is sufficient for performing quantum gate experiments in Pr^{+3}:Y_2SiO_5.

L. Rippe; B. Julsgaard; A. Walther; S. Krll

2006-11-05T23:59:59.000Z

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401

Geometric description of BTZ black holes thermodynamics  

E-Print Network [OSTI]

We study the properties of the space of thermodynamic equilibrium states of the Ba\\~nados-Teitelboim-Zanelli (BTZ) black hole in (2+1)-gravity. We use the formalism of geometrothermodynamics to introduce in the space of equilibrium states a $2-$dimensional thermodynamic metric whose curvature is non-vanishing, indicating the presence of thermodynamic interaction, and free of singularities, indicating the absence of phase transitions. Similar results are obtained for generalizations of the BTZ black hole which include a Chern-Simons term and a dilatonic field. Small logarithmic corrections of the entropy turn out to be represented by small corrections of the thermodynamic curvature, reinforcing the idea that thermodynamic curvature is a measure of thermodynamic interaction.

Hernando Quevedo; Alberto Sanchez

2008-11-15T23:59:59.000Z

402

Hybrid black-hole binary initial data  

E-Print Network [OSTI]

Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class.Quant.Grav.27:114005,2010], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculation was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features.

Bruno C. Mundim; Bernard J. Kelly; Yosef Zlochower; Hiroyuki Nakano; Manuela Campanelli

2010-12-04T23:59:59.000Z

403

The high energy emission from black holes  

E-Print Network [OSTI]

The origin of the high energy emission (X-rays and gamma-rays) from black holes is still a matter of debate. We present new evidence that hard X-ray emission in the low/hard state may not be dominated by thermal Comptonization. We present an alternative scenario for the origin of the high energy emission that is well suited to explain the high energy emission from GRO J1655-40.

M. D. Caballero-Garcia; J. M. Miller; E. Kuulkers

2007-11-06T23:59:59.000Z

404

Black hole remnants in the early universe  

Science Journals Connector (OSTI)

We consider the production of primordial micro black holes (MBH) remnants in the early Universe. These objects induce the Universe to be in a matter-dominated era before the onset of inflation. Effects of such an epoch on the CMB power spectrum are discussed and computed both analytically and numerically. By comparison with the latest observational data from the WMAP collaboration, we find that our model appears to explain the quadrupole anomaly of the CMB power spectrum.

Fabio Scardigli; Christine Gruber; Pisin Chen

2011-03-09T23:59:59.000Z

405

Hole cleaning requirements with seabed returns  

E-Print Network [OSTI]

size and fluid density. The least important were rotary speed, feed concentration, annulus size, and drillpipe eccentricity. They also reported that, in Newtonian fluids, transport efficiency improves with increasing viscosity; however, they noted... is set; therefore, no marine riser can be utilized. The coring occurs up to 3000 ft below the seafloor with the bit cutting an 11. 438 in. hole. The rig pumps have a maximum output of 600 gpm under normal coring operations with untreated seawater...

Nordt, David Paul

1988-01-01T23:59:59.000Z

406

Comparing quantum black holes and naked singularities  

E-Print Network [OSTI]

There are models of gravitational collapse in classical general relativity which admit the formation of naked singularities as well as black holes. These include fluid models as well as models with scalar fields as matter. Even if fluid models were to be regarded as unphysical in their matter content, the remaining class of models (based on scalar fields) generically admit the formation of visible regions of finite but arbitrarily high curvature. Hence it is of interest to ask, from the point of view of astrophysics, as to what a stellar collapse leading to a naked singularity (or to a visible region of very high curvature) will look like, to a far away observer. The emission of energy during such a process may be divided into three phases - (i) the classical phase, during which matter and gravity can both be treated according to the laws of classical physics, (ii) the semiclassical phase, when gravity is treated classically but matter behaves as a quantum field, and (iii) the quantum gravitational phase. In this review, we first give a summary of the status of naked singularities in classical relativity, and then report some recent results comparing the semiclassical phase of black holes with the semiclassical phase of spherical collapse leading to a naked singularity. In particular, we ask how the quantum particle creation during the collapse leading to a naked singularity compares with the Hawking radiation from a star collapsing to form a black hole. It turns out that there is a fundamental difference between the two cases. A spherical naked star emits only about one Planck energy during its semiclassical phase, and the further evolution can only be determined by the laws of quantum gravity. This contrasts with the semiclassical evaporation of a black hole.

T. P. Singh

2000-12-21T23:59:59.000Z

407

The stellar accretion origin of stellar population gradients in massive galaxies at large radii  

E-Print Network [OSTI]

We investigate the evolution of stellar population gradients from $z=2$ to $z=0$ in massive galaxies at large radii ($r > 2R_{\\mathrm{eff}}$) using ten cosmological zoom simulations of halos with $6 \\times 10^{12} M_{\\odot} simulations follow metal cooling and enrichment from SNII, SNIa and AGB winds. We explore the differential impact of an empirical model for galactic winds that reproduces the mass-metallicity relation and its evolution with redshift. At larger radii the galaxies, for both models, become more dominated by stars accreted from satellite galaxies in major and minor mergers. In the wind model, fewer stars are accreted, but they are significantly more metal poor resulting in steep global metallicity ($\\langle \

Hirschmann, Michaela; Ostriker, Jeremiah P; Forbes, Duncan A; Duc, Pierre-Alain; Dav, Romeel; Oser, Ludwig; Karabal, Emin

2014-01-01T23:59:59.000Z

408

Analytic energy gradients for constrained DFT-configuration interaction  

SciTech Connect (OSTI)

The constrained density functional theory-configuration interaction (CDFT-CI) method has previously been used to calculate ground-state energies and barrier heights, and to describe electronic excited states, in particular conical intersections. However, the method has been limited to evaluating the electronic energy at just a single nuclear configuration, with the gradient of the energy being available only via finite difference. In this paper, we present analytic gradients of the CDFT-CI energy with respect to nuclear coordinates, which gives the potential for accurate geometry optimization and molecular dynamics on both the ground and excited electronic states, a realm which is currently quite challenging for electronic structure theory. We report the performance of CDFT-CI geometry optimization for representative reaction transition states as well as molecules in an excited state. The overall accuracy of CDFT-CI for computing barrier heights is essentially unchanged whether the energies are evaluated at geometries obtained from quadratic configuration-interaction singles and doubles (QCISD) or CDFT-CI, indicating that CDFT-CI produces very good reaction transition states. These results open up tantalizing possibilities for future work on excited states.

Kaduk, Benjamin; Tsuchimochi, Takashi; Van Voorhis, Troy, E-mail: tvan@mit.edu [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

2014-05-14T23:59:59.000Z

409

Ultra-High Gradient Dielectric Wakefield Accelerator Experiments  

SciTech Connect (OSTI)

Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {micro}m/OD = 325 {micro}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.

Thompson, M C; Badakov, H; Rosenzweig, J B; Travish, G; Hogan, M; Ischebeck, R; Kirby, N; Siemann, R; Walz, D; Muggli, P; Scott, A; Yoder, R

2006-08-04T23:59:59.000Z

410

Ultra-High Gradient Dielectric Wakefield Accelerator Experiments  

SciTech Connect (OSTI)

Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}z = 20 {mu}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {mu}m / OD = 325 {mu}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.

Thompson, M. C. [Lawrence Livermore National Laboratory, Livermore, California, 90095 (United States); Badakov, H.; Rosenzweig, J. B.; Travis, G. [UCLA Department of Physics and Astronomy, Los Angeles, California, 90095 (United States); Hogan, M.; Ischebeck, R.; Kirby, N.; Siemann, R.; Walz, D. [Stanford Linear Accelerator Center, Stanford, California, 94309 (United States); Muggli, P. [University of Southern California Los Angeles, California, 90089 (United States); Scott, A. [UCSB Department of Physics, Santa Barbara, California, 93106 (United States); Yoder, R. [Manhattan College, Riverdale, New York, 10471 (United States)

2006-11-27T23:59:59.000Z

411

Spectral hole burning for stopping light  

SciTech Connect (OSTI)

We propose a protocol for storage and retrieval of photon wave packets in a {lambda}-type atomic medium. This protocol derives from spectral hole burning and takes advantages of the specific properties of solid-state systems at low temperature, such as rare-earth ion-doped crystals. The signal pulse is tuned to the center of the hole that has been burnt previously within the inhomogeneously broadened absorption band. The group velocity is strongly reduced, being proportional to the hole width. This way the optically carried information and energy are carried over to the off-resonance optical dipoles. Storage and retrieval are performed by conversion to and from ground-state Raman coherence by using brief {pi} pulses. The protocol exhibits some resemblance with the well-known electromagnetically induced transparency process. It also presents distinctive features such as the absence of coupling beam. In this paper we detail the various steps of the protocol, summarize the critical parameters, and theoretically examine the recovery efficiency.

Lauro, R.; Chaneliere, T.; Le Goueet, J.-L. [Laboratoire Aime Cotton, CNRS UPR3321, Universite Paris Sud, Batiment 505, Campus Universitaire, 91405 Orsay (France)

2009-05-15T23:59:59.000Z

412

Dark jets in solar coronal holes  

E-Print Network [OSTI]

A new solar feature termed a dark jet is identified from observations of an extended solar coronal hole that was continuously monitored for over 44 hours by the EUV Imaging Spectrometer on board the Hinode spacecraft in 2011 February 8-10. Line-of-sight velocity maps derived from the coronal Fe XII $\\lambda$195.12 emission line, formed at 1.5 MK, revealed a number of large-scale, jet-like structures that showed significant blueshifts. The structures had either weak or no intensity signal in 193 A filter images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, suggesting that the jets are essentially invisible to imaging instruments. The dark jets are rooted in bright points and occur both within the coronal hole and at the quiet Sun-coronal hole boundary. They exhibit a wide range of shapes, from narrow columns to fan-shaped structures, and sometimes multiple jets are seen close together. A detailed study of one dark jet showed line-of-sight speeds increasing along the jet axis fr...

Young, Peter R

2015-01-01T23:59:59.000Z

413

Quantization of rotating linear dilaton black holes  

E-Print Network [OSTI]

In this paper, we firstly prove that the adiabatic invariant quantity, which is commonly used in the literature for quantizing the rotating black holes (BHs) is fallacious. We then show how its corrected form should be. The main purpose of this paper is to study the quantization of 4-dimensional rotating linear dilaton black hole (RLDBH) spacetime describing with an action, which emerges in the Einstein-Maxwell-Dilaton-Axion (EMDA) theory. The RLDBH spacetime has a non-asymptotically flat (NAF) geometry. They reduces to the linear dilaton black hole (LDBH) metric when vanishing its rotation parameter $a$. While studying its scalar perturbations, it is shown that the Schr\\"odinger-like wave equation around the event horizon reduces to a confluent hypergeometric differential equation. Then the associated complex frequencies of the quasinormal modes (QNMs) are computed. By using those QNMs in the true definition of the rotational adiabatic invariant quantity, we obtain the quantum spectra of entropy/area for the RLDBH. It is found out that both spectra are discrete and equidistant. Besides, we reveal that the quantum spectra do not depend on $a$ in spite of the QNMs are modulated by it.

I. Sakalli

2014-06-19T23:59:59.000Z

414

Dielectric-Lined High-Gradient Accelerator Structure  

SciTech Connect (OSTI)

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30 GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M{Omega}/m for DLA, as compared to 99 M{Omega}/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

Jay L. Hirshfield

2012-04-24T23:59:59.000Z

415

Hole transport in the rare-gas solids Ne, Ar, Kr, and Xe  

Science Journals Connector (OSTI)

This paper reports an investigation of the drift mobility of excess holes in solid Ne, Ar, Kr, and Xe. Thin-crystal specimens (50-500 ?m thick) were grown from the liquid between parallel-plate electrodes in a chamber attached to a miniature cryostat after purification of the starting gas. As in previous work on the electron transport in rare-gas solids and liquids, an electron-beam technique was used to generate excess carriers near one of the electrodes. Holes were extracted by the applied field and their transit time was measured directly, leading to the drift mobility ?h. Close to the triple points, ?h values in the above crystals lie between 1 10-2 and 4 10-2 cm2 V-1 sec-1, several orders of magnitude lower than the corresponding electron mobilities. The form of the temperature dependence of ?h changes progressively from Xe(?h?T-1.6) to an essentially activated mobility in Ar and Ne. The experimental results have been analyzed in terms of small-polaron theory, using both the adiabatic and nonadiabatic approximations. The theory can account for the different forms of the temperature dependence and possible ranges of values for the predominant phonon energy, the polaron binding energy and the transfer energy for holes have been deduced in each case. These quantities, characterizing the hole hopping transport, vary systematically from Xe to Ne and their correlation is discussed in some detail.

P. G. Le Comber; R. J. Loveland; W. E. Spear

1975-04-15T23:59:59.000Z

416

Is the firewall consistent? Gedanken experiments on black hole complementarity and firewall proposal  

SciTech Connect (OSTI)

In this paper, we discuss the black hole complementarity and the firewall proposal at length. Black hole complementarity is inevitable if we assume the following five things: unitarity, entropy-area formula, existence of an information observer, semi-classical quantum field theory for an asymptotic observer, and the general relativity for an in-falling observer. However, large N rescaling and the AMPS argument show that black hole complementarity is inconsistent. To salvage the basic philosophy of the black hole complementarity, AMPS introduced a firewall around the horizon. According to large N rescaling, the firewall should be located close to the apparent horizon. We investigate the consistency of the firewall with the two critical conditions: the firewall should be near the time-like apparent horizon and it should not affect the future infinity. Concerning this, we have introduced a gravitational collapse with a false vacuum lump which can generate a spacetime structure with disconnected apparent horizons. This reveals a situation that there is a firewall outside of the event horizon, while the apparent horizon is absent. Therefore, the firewall, if it exists, not only does modify the general relativity for an in-falling observer, but also modify the semi-classical quantum field theory for an asymptotic observer.

Hwang, Dong-il; Lee, Bum-Hoon; Yeom, Dong-han, E-mail: dongil.j.hwang@gmail.com, E-mail: bhl@sogang.ac.kr, E-mail: innocent.yeom@gmail.com [Center for Quantum Spacetime, Sogang University, Seoul 121-742 (Korea, Republic of)

2013-01-01T23:59:59.000Z

417

Black holes in the tensor-vector-scalar theory of gravity and their thermodynamics  

SciTech Connect (OSTI)

Tensor-vector-scalar (TeVeS) theory, a relativistic theory of gravity, was designed to provide a basis for the modified Newtonian dynamics. Since TeVeS differs from general relativity (e.g., it has two metrics, an Einstein metric and a physical metric), black hole solutions of it would be valuable for a number of endeavors ranging from astrophysical modeling to investigations into the interrelation between gravity and thermodynamics. Giannios has recently found a TeVeS analogue of the Schwarzschild black hole solution. We proceed further with the program by analytically solving the TeVeS equations for a static spherically symmetric and asymptotically flat system of electromagnetic and gravity fields. We show that one solution is provided by the Reissner-Nordstroem metric as physical metric, the TeVeS vector field pointing in the time direction, and a TeVeS scalar field positive everywhere (the last feature protects from superluminal propagation of disturbances in the fields). We work out black hole thermodynamics in TeVeS using the physical metric; black hole entropy, temperature, and electric potential turn out to be identical to those in general relativity. We find it inconsistent to base thermodynamics on the Einstein metric. In light of this, we reconsider the Dubovsky-Sibiryakov scenario for violating the second law of thermodynamics in theories with Lorentz symmetry violation.

Sagi, Eva; Bekenstein, Jacob D. [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

2008-01-15T23:59:59.000Z

418

Gravitational radiation and angular momentum flux from a slowly rotating dynamical black hole  

SciTech Connect (OSTI)

A four-dimensional asymptotic expansion scheme is used to study the next-order effects of the nonlinearity near a spinning dynamical black hole. The angular-momentum flux and energy flux formula are then obtained by constructing the reference frame in terms of the compatible constant spinors and the compatibility of the coupling leading-order Newman-Penrose equations. By using the slow rotation and small-tide approximation for a spinning black hole, the horizon cross-section we chose is spherical symmetric. It turns out the flux formula is rather simple and can be compared with the known results. Directly from the energy flux formula of the slow-rotating dynamical horizon, we find that the physically reasonable condition on requiring the positivity of the gravitational energy flux yields that the shear will monotonically decrease with time. Thus a slow-rotating dynamical horizon will asymptotically approach an isolated horizon during late time.

Wu, Yu-Huei; Wang, Chih-Hung [Center for Mathematics and Theoretical Physics, National Central University, Chungli, 320, Taiwan (China) and Department of Physics, National Central University, Chungli, 320, Taiwan (China); Department of Physics, Tamkang University, Tamsui, Taipei 25137, Taiwan (China) and Institute of Physics, Academia Sinica, Taipei 115, Taiwan and Department of Physics, National Central University, Chungli, 320, Taiwan (China)

2011-04-15T23:59:59.000Z

419

Composition-tailored synthesis of gradient transition metal precursor particles for lithium-ion battery cathode materials.  

SciTech Connect (OSTI)

We report the tailored synthesis of particles with internal gradients in transition metal composition aided by the use of a general process model. Tailored synthesis of transition metal particles was achieved using a coprecipitation reaction with tunable control over the process conditions. Gradients in the internal composition of the particles was monitored and confirmed experimentally by analysis of particles collected during regularly timed intervals. Particles collected from the reactor at the end of the process were used as the precursor material for the solid-state synthesis of Li{sub 1.2}(Mn{sub 0.62}Ni{sub 0.38}){sub 0.8}O{sub 2}, which was electrochemically evaluated as the active cathode material in a lithium battery. The Li{sub 1.2}(Mn{sub 0.62}Ni{sub 0.38}){sub 0.8}O{sub 2} material was the first example of a structurally integrated multiphase material with a tailored internal gradient in relative transition metal composition as the active cathode material in a lithium-ion battery. We believe our general synthesis strategy may be applied to produce a variety of new cathode materials with tunable interior, surface, and overall relative transition metal compositions.

Koenig, G. M.; Belharouak, I.; Deng, H.; Amine, K.; Sun, Y. K. (Chemical Sciences and Engineering Division)

2011-04-12T23:59:59.000Z

420

K-Shell-Hole Production, Multiple-Hole Production, Charge-Transfer, and Antisymmetry  

E-Print Network [OSTI]

-shell electron can occur. For example, after making a K-shell hole an L-shell electron may be knocked into it, or an L-shell vacancy may be produced and the K-shell electron promoted to that vacancy in the "Fermi sea" of the target-atom orbitals, In 1973 a.... If one is working in first-order pertur- bation theory E-shell-hole production is correctly obtained by calculating the process for the K elec- tron to be lifted above the "Fermi sea" of occupied target orbitals, i.e., the other electrons play a...

Reading, John F.; Ford, A. Lewis.

1980-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

The inner edge of the accretion disk around a supermassive black hole  

Science Journals Connector (OSTI)

... material giving rise to the line is within 2.6 0.3 times the Schwarzschild radiusthe event horizon of a non-rotating black holeat the 95% confidence ... of the disk is within a few Rs (where Rs ? 2GM/c2 is the Schwarzschild radius) of an object of mass M. Unfortunately, the inner radius inferred from ...

B. C. Bromley; W. A. Miller; V. I. Pariev

1998-01-01T23:59:59.000Z

422

Mineral Test Hole Regulatory Act (Tennessee) | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

Mineral Test Hole Regulatory Act (Tennessee) Mineral Test Hole Regulatory Act (Tennessee) Mineral Test Hole Regulatory Act (Tennessee) < Back Eligibility Commercial Construction Developer Fuel Distributor Industrial Installer/Contractor Investor-Owned Utility Municipal/Public Utility Utility Program Info State Tennessee Program Type Environmental Regulations Siting and Permitting Provider Tennessee Department Of Environment and Conservation The Mineral Hole Regulatory Act is applicable to any person (individual, corporation, company, association, joint venture, partnership, receiver, trustee, guardian, executor, administrator, personal representative or private organization of any kind) who wishes to drill a mineral test hole (any hole in excess of one hundred (100) feet drilled during the exploration for minerals but shall exclude auger drilling in surficial or

423

Video: Part of the 'Hole' Story (of Uranium Hexafluoride Cylinders)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hole Story Hole Story Part of the "Hole" Story (of Uranium Hexafluoride Cylinders) Holes in the depleted Uranium Hexafluoride storage cylinders are investigated. It is shown that corrosion products cause the openings to be self-healing. View this Video in Real Player format Download free RealPlayer SP Highlights of the Video: Video 00:00 Part of the 'Hole' Story Video 00:05 One of the depleted UF6 cylinder storage lots at Portsmouth Video 00:28 48G cylinders, each containing 14 tons of depleted UF6, in storage Video 00:52 Stacked 48G cylinders Video 01:35 UF6 sealed in glass tube Video 02:01 A lifting lug of one cylinder damaging a neighboring cylinder Video 02:37 Damage to small hole cylinder from impact with a lifting lub of an adjoining cylinder

424

Articles which include chevron film cooling holes, and related processes  

DOE Patents [OSTI]

An article is described, including an inner surface which can be exposed to a first fluid; an inlet; and an outer surface spaced from the inner surface, which can be exposed to a hotter second fluid. The article further includes at least one row or other pattern of passage holes. Each passage hole includes an inlet bore extending through the substrate from the inlet at the inner surface to a passage hole-exit proximate to the outer surface, with the inlet bore terminating in a chevron outlet adjacent the hole-exit. The chevron outlet includes a pair of wing troughs having a common surface region between them. The common surface region includes a valley which is adjacent the hole-exit; and a plateau adjacent the valley. The article can be an airfoil. Related methods for preparing the passage holes are also described.

Bunker, Ronald Scott; Lacy, Benjamin Paul

2014-12-09T23:59:59.000Z

425

Method and apparatus of assessing down-hole drilling conditions  

DOE Patents [OSTI]

A method and apparatus for use in assessing down-hole drilling conditions are disclosed. The apparatus includes a drill string, a plurality of sensors, a computing device, and a down-hole network. The sensors are distributed along the length of the drill string and are capable of sensing localized down-hole conditions while drilling. The computing device is coupled to at least one sensor of the plurality of sensors. The data is transmitted from the sensors to the computing device over the down-hole network. The computing device analyzes data output by the sensors and representative of the sensed localized conditions to assess the down-hole drilling conditions. The method includes sensing localized drilling conditions at a plurality of points distributed along the length of a drill string during drilling operations; transmitting data representative of the sensed localized conditions to a predetermined location; and analyzing the transmitted data to assess the down-hole drilling conditions.

Hall, David R. (Provo, UT); Pixton, David S. (Lehl, UT); Johnson, Monte L. (Orem, UT); Bartholomew, David B. (Springville, UT); Fox, Joe (Spanish Fork, UT)

2007-04-24T23:59:59.000Z

426

Hole Self-Energy Corrections in the Brueckner Theory  

Science Journals Connector (OSTI)

To study corrections to hole propagators in Brueckner theory, an extension of the Hugenholtz convolution theorem is proved. An integral equation is derived for a class of Brueckner hole corrections and approximate solutions are obtained, one of which gives the usual prescription that makes holes propagate on the energy shell. The derivation shows which class of diagrams are included in this prescription and suggests that a more accurate treatment might be needed.

J. Nuttall

1966-09-23T23:59:59.000Z

427

A toroidal black hole for the AGN phenomenon  

E-Print Network [OSTI]

A new approach to the study of the AGN phenomenon is proposed, in which the nucleus activity is related to the metric of the inner massive black hole. The possibility of a Toroidal Black Hole (TBH), in contrast to the usual Spherical Black Hole (SBH), is discussed as a powerful tool in understanding AGN related phenomena, such as the energetics, the production of jets and the acceleration of particles, the shape of the magnetic field and the lifetime of nucleus activity.

Fulvio Pompilio; S. M. Harun-or-Rashid; Matts Roos

2000-08-30T23:59:59.000Z

428

On the Stability of Black Holes at the LHC  

E-Print Network [OSTI]

The eventual production of mini black holes by proton-proton collisions at the LHC is predicted by theories with large extra dimensions resolvable at the Tev scale of energies. It is expected that these black holes evaporate shortly after its production as a consequence of the Hawking radiation. We show that for theories based on the ADS/CFT correspondence, the produced black holes may have an unstable horizon, which grows proportionally to the square of the distance to the collision point.

M. D. Maia; E. M. Monte

2008-08-19T23:59:59.000Z

429

Exploring approximations to the GW self-energy ionic gradients  

E-Print Network [OSTI]

The accuracy of the many-body perturbation theory GW formalism to calculate electron-phonon coupling matrix elements has been recently demonstrated in the case of a few important systems. However, the related computational costs are high and thus represent strong limitations to its widespread application. In the present study, we explore two less demanding alternatives for the calculation of electron-phonon coupling matrix elements on the many-body perturbation theory level. Namely, we test the accuracy of the static Coulomb-hole plus screened-exchange (COHSEX) approximation and further of the constant screening approach, where variations of the screened Coulomb potential W upon small changes of the atomic positions along the vibrational eigenmodes are neglected. We find this latter approximation to be the most reliable, whereas the static COHSEX ansatz leads to substantial errors. Our conclusions are validated in a few paradigmatic cases: diamond, graphene and the C60 fullerene. These findings open the way f...

Faber, C; Attaccalite, C; Cannuccia, E; Duchemin, I; Deutsch, T; Blase, X

2015-01-01T23:59:59.000Z

430

Ion temperature gradient driven turbulence with strong trapped ion resonance  

SciTech Connect (OSTI)

A theory to describe basic characterization of ion temperature gradient driven turbulence with strong trapped ion resonance is presented. The role of trapped ion granulations, clusters of trapped ions correlated by precession resonance, is the focus. Microscopically, the presence of trapped ion granulations leads to a sharp (logarithmic) divergence of two point phase space density correlation at small scales. Macroscopically, trapped ion granulations excite potential fluctuations that do not satisfy dispersion relation and so broaden frequency spectrum. The line width from emission due only to trapped ion granulations is calculated. The result shows that the line width depends on ion free energy and electron dissipation, which implies that non-adiabatic electrons are essential to recover non-trivial dynamics of trapped ion granulations. Relevant testable predictions are summarized.

Kosuga, Y., E-mail: kosuga@riam.kyushu-u.ac.jp [Institute for Advanced Study, Kyushu University, Fukuoka (Japan); Research Institute for Applied Mechanics, Kyushu University, Fukuoka (Japan); Itoh, S.-I. [Research Center for Plasma Turbulence, Kyushu University, Fukuoka (Japan); Research Institute for Applied Mechanics, Kyushu University, Fukuoka (Japan); Diamond, P. H. [CASS and CMTFO, University of California at San Diego, La Jolla, California 92093 (United States); WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon (Korea, Republic of); Itoh, K. [National Institute for Fusion Science, Gifu (Japan); Research Center for Plasma Turbulence, Kyushu University, Fukuoka (Japan); Lesur, M. [Research Institute for Applied Mechanics, Kyushu University, Fukuoka (Japan)

2014-10-15T23:59:59.000Z

431

Modified Magnicon for High-Gradient Accelerator R&D  

SciTech Connect (OSTI)

Analysis, and low-power cold tests are described on a modified design intended for the Ka-band pulsed magnicon now in use for high-gradient accelerator R and D and rare elementary particle searches at the Yale University Beam Physics Laboratory. The modification is mainly to the output cavity of the magnicon, which presently operates in the TM310 mode. It is proposed to substitute for this a dual-chamber TE311 cavity structure. The first chamber is to extract about 40% of the beam power (about 25 MW) at 34.272 GHz, while the second chamber is to convey the power to four WR-28 output waveguides. Minor design changes are also proposed for the penultimate 11.424 GHz cavity and the beam collector. The intention of these design changes is to allow the magnicon to operate reliably 24/7, with minor sensitivity to operating parameters.

Jay L. Hirshfield

2011-12-19T23:59:59.000Z

432

Optimization of the Oktay-Kronfeld Action Conjugate Gradient Inverter  

E-Print Network [OSTI]

Improving the Fermilab action to third order in heavy quark effective theory yields the Oktay-Kronfeld action, a promising candidate for precise calculations of the spectra of heavy quark systems and weak matrix elements relevant to searches for new physics. We have optimized the bi-stabilized conjugate gradient inverter in the SciDAC QOPQDP library and are developing a GPU code. The action is rewritten and the needed gauge-link combinations are precalculated. In tests with a MILC coarse lattice, this procedure accelerates the inverter by a factor of four. The remaining floating-point operations are mostly simple matrix multiplications between gauge links and fermion vectors, which we accelerate by more than an order of magnitude by using CUDA. Further gains could be achieved by using QUDA.

Yong-Chull Jang; Jon A. Bailey; Weonjong Lee; Carleton DeTar; Mehmet B. Oktay; Andreas S. Kronfeld

2013-11-21T23:59:59.000Z

433

Salinity gradient solar pond technology applied to potash solution mining  

SciTech Connect (OSTI)

A solution mining facility at the Eddy Potash Mine, Eddy County, New Mexico has been proposed that will utilize salinity gradient solar pond (SGSP) technology to supply industrial process thermal energy. The process will include underground dissolution of potassium chloride (KCl) from pillars and other reserves remaining after completion of primary room and pillar mining using recirculating solutions heated in the SGSP. Production of KCl will involve cold crystallization followed by a cooling pond stage, with the spent brine being recirculated in a closed loop back to the SGSP for reheating. This research uses SGSP as a renewable, clean energy source to optimize the entire mining process, minimize environmental wastes, provide a safe, more economical extraction process and reduce the need for conventional processing by crushing, grinding and flotation. The applications of SGSP technology will not only save energy in the extraction and beneficiation processes, but also will produce excess energy available for power generation, desalination, and auxiliary structure heating.

Martell, J.A.; Aimone-Martin, C.T.

2000-06-12T23:59:59.000Z

434

Coherent structures in ion temperature gradient turbulence-zonal flow  

SciTech Connect (OSTI)

Nonlinear stationary structure formation in the coupled ion temperature gradient (ITG)-zonal flow system is investigated. The ITG turbulence is described by a wave-kinetic equation for the action density of the ITG mode, and the longer scale zonal mode is described by a dynamic equation for the m?=?n?=?0 component of the potential. Two populations of trapped and untrapped drift wave trajectories are shown to exist in a moving frame of reference. This novel effect leads to the formation of nonlinear stationary structures. It is shown that the ITG turbulence can self-consistently sustain coherent, radially propagating modulation envelope structures such as solitons, shocks, and nonlinear wave trains.

Singh, Rameswar, E-mail: rameswar.singh@lpp.polytechnique.fr [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Singh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Kaw, P. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Grcan, . D. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Diamond, P. H. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); CMTFO and CASS, University of California, San Diego, California 92093 (United States)

2014-10-15T23:59:59.000Z

435

Hydrodynamic model for electron-hole plasma in graphene  

E-Print Network [OSTI]

We propose a hydrodynamic model describing steady-state and dynamic electron and hole transport properties of graphene structures which accounts for the features of the electron and hole spectra. It is intended for electron-hole plasma in graphene characterized by high rate of intercarrier scattering compared to external scattering (on phonons and impurities), i.e., for intrinsic or optically pumped (bipolar plasma), and gated graphene (virtually monopolar plasma). We demonstrate that the effect of strong interaction of electrons and holes on their transport can be treated as a viscous friction between the electron and hole components. We apply the developed model for the calculations of the graphene dc conductivity, in particular, the effect of mutual drag of electrons and holes is described. The spectra and damping of collective excitations in graphene in the bipolar and monopolar limits are found. It is shown that at high gate voltages and, hence, at high electron and low hole densities (or vice-versa), the excitations are associated with the self-consistent electric field and the hydrodynamic pressure (plasma waves). In intrinsic and optically pumped graphene, the waves constitute quasineutral perturbations of the electron and hole densities (electron-hole sound waves) with the velocity being dependent only on the fundamental graphene constants.

D. Svintsov; V. Vyurkov; S. Yurchenko; T. Otsuji; V. Ryzhii

2012-01-03T23:59:59.000Z

436

Core Holes At Blue Mountain Geothermal Area (Fairbank & Niggemann...  

Open Energy Info (EERE)

Exploration Activity Details Location Blue Mountain Geothermal Area Exploration Technique Core Holes Activity Date 2002 - 2004 Usefulness useful DOE-funding Unknown Exploration...

437

Comparison of Black Hole Generators for the LHC  

E-Print Network [OSTI]

We compare Monte Carlo event generators dedicated to simulating the production and decay of extra-dimensional black holes at the Large Hadron Collider.

Douglas M. Gingrich

2006-10-17T23:59:59.000Z

438

A rotating black hole in the Galactic Center  

E-Print Network [OSTI]

Recent observations of Sgr A* give strong constraints for possible models of the physical nature of Sgr A* and suggest the presence of a massive black~hole with M0.9) accreting 10^-8.5 - 10^-7 M_sun/yr at a black~hole mass of M=2 10^6 M_sunseen almost edge on. A low mass black hole of M' together with simple scaling laws to provide an easy-to-handle test for the black hole model.

Heino Falcke; Peter L. Biermann; Wolfgang J. Duschl; Peter G. Mezger

1992-12-07T23:59:59.000Z

439

Hole doping in high temperature superconductors using the XANES technique  

E-Print Network [OSTI]

Hole doping in high temperature superconductors using the1994 Thallium-Based High Temperature Superconductors ed A M1994 Thallium-Based High Temperature Superconductors ed A M

Hamdan, Nasser

2012-01-01T23:59:59.000Z

440

Core Holes At Long Valley Caldera Geothermal Area (Eichelberger...  

Open Energy Info (EERE)

Eichelberger, Et Al., 1988) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Core Holes At Long Valley Caldera Geothermal Area (Eichelberger, Et...

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Core Holes At Steamboat Springs Area (Warpinski, Et Al., 2004...  

Open Energy Info (EERE)

Steamboat Springs Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Core Holes At Steamboat Springs Area (Warpinski,...

442

Core Holes At Long Valley Caldera Geothermal Area (Urban, Et...  

Open Energy Info (EERE)

Urban, Et Al., 1987) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Core Holes At Long Valley Caldera Geothermal Area (Urban, Et Al., 1987)...

443

Slim Holes At Blue Mountain Area (Warpinski, Et Al., 2002) |...  

Open Energy Info (EERE)

Blue Mountain Area (Warpinski, Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Slim Holes At Blue Mountain Area (Warpinski, Et Al.,...

444

Using the Uncharged Kerr Black Hole as a Gravitational Mirror  

Science Journals Connector (OSTI)

We extend the study of the possible use of the Schwarzschild black hole as a gravitational mirror to the more general case of an...

Claes R. Cramer

1997-04-01T23:59:59.000Z

445

The first law of thermodynamics in Lifshitz black holes revisited  

E-Print Network [OSTI]

We obtain the mass expression of the three- and five-dimensional Lifshitz black holes by em- ploying the recently proposed quasilocal formulation of conserved charges, which is based on the off-shell extension of the ADT formalism. Our result is consistent with the first law of black hole thermodynamics and resolves the reported discrepancy between the ADT formalism and the other conventional methods. The same mass expression of Lifshitz black holes is obtained by using an- other quasilocal method by Padmanabhan. We also discuss the reported discrepancy in the context of the extended first law of black hole thermodynamics by allowing the pressure term.

Yongwan Gim; Wontae Kim; Sang-Heon Yi

2014-03-19T23:59:59.000Z

446

Absorption of scalars by extremal black holes in string theory  

E-Print Network [OSTI]

We show that the low frequency absorption cross section of minimally coupled massless scalar fields by extremal spherically symmetric black holes in d dimensions in the presence of string-theoretical alpha' corrections is equal to the horizon area. Classically one has the relation sigma=4GS between the absorption cross section and the black hole entropy. We discuss the validity of such relation in the presence of alpha' corrections for extremal black holes, both nonsupersymmetric and supersymmetric. The examples we consider seem to indicate that this relation is verified in the presence of alpha' corrections for supersymmetric black holes, but not for nonsupersymmetric ones.

Filipe Moura

2014-06-13T23:59:59.000Z

447

Core Holes At Valles Caldera - Redondo Geothermal Area (Goff...  

Open Energy Info (EERE)

understand the stratigraphy, structure, hydrothermal alteration, and subsurface architecture of the Valles caldera. Several authors have reported results from these core holes,...

448

Core Holes At Valles Caldera - Sulphur Springs Geothermal Area...  

Open Energy Info (EERE)

understand the stratigraphy, structure, hydrothermal alteration, and subsurface architecture of the Valles caldera. Several authors have reported results from these core holes,...

449

Location Of Hole And Electron Traps On Nanocrystalline Anatase...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission...

450

Extremal charged rotating dilaton black holes in odd dimensions  

SciTech Connect (OSTI)

Employing higher-order perturbation theory, we find a new class of charged rotating black hole solutions of Einstein-Maxwell-dilaton theory with general dilaton coupling constant. Starting from the Myers-Perry solutions, we use the electric charge as the perturbative parameter, and focus on extremal black holes with equal-magnitude angular momenta in odd dimensions. We perform the perturbations up to 4th order for black holes in 5 dimensions and up to 3rd order in higher odd dimensions. We calculate the physical properties of these black holes and study their dependence on the charge and the dilaton coupling constant.

Allahverdizadeh, Masoud; Kunz, Jutta; Navarro-Lerida, Francisco [Institut fuer Physik, Universitaet Oldenburg, Postfach 2503 D-26111 Oldenburg (Germany); Departamento de Fisica Atomica, Molecular y Nuclear, Ciencias Fisicas Universidad Complutense de Madrid, E-28040 Madrid (Spain)

2010-09-15T23:59:59.000Z

451

Extremal Charged Rotating Dilaton Black Holes in Odd Dimensions  

E-Print Network [OSTI]

Employing higher order perturbation theory, we find a new class of charged rotating black hole solutions of Einstein-Maxwell-dilaton theory with general dilaton coupling constant. Starting from the Myers-Perry solutions, we use the electric charge as the perturbative parameter, and focus on extremal black holes with equal-magnitude angular momenta in odd dimensions. We perform the perturbations up to 4th order for black holes in 5 dimensions and up to 3rd order in higher odd dimensions. We calculate the physical properties of these black holes and study their dependence on the charge and the dilaton coupling constant.

Masoud Allahverdizadeh; Jutta Kunz; Francisco Navarro-Lerida

2010-07-24T23:59:59.000Z

452

Parametric down conversion with a depleted pump as a model for classical information transmission capacity of quantum black holes  

E-Print Network [OSTI]

In this paper we extend the investigation of Adami and Ver Steeg [Class. Quantum Grav. \\textbf{31}, 075015 (2014)] to treat the process of black hole particle emission effectively as the analogous quantum optical process of parametric down conversion (PDC) with a dynamical (depleted vs. non-depleted) `pump' source mode which models the evaporating black hole (BH) energy degree of freedom. We investigate both the short time (non-depleted pump) and long time (depleted pump) regimes of the quantum state and its impact on the Holevo channel capacity for communicating information from the far past to the far future in the presence of Hawking radiation. The new feature introduced in this work is the coupling of the emitted Hawking radiation modes through the common black hole `source pump' mode which phenomenologically represents a quantized energy degree of freedom of the gravitational field. This (zero-dimensional) model serves as a simplified arena to explore BH particle production/evaporation and back-action effects under an explicitly unitary evolution which enforces quantized energy/particle conservation. Within our analogous quantum optical model we examine the entanglement between two emitted particle/anti-particle and anti-particle/particle pairs coupled via the black hole (BH) evaporating `pump' source. We also analytically and dynamically verify the `Page information time' for our model which refers to the conventionally held belief that the information in the BH radiation becomes significant after the black hole has evaporated half its initial energy into the outgoing radiation. Lastly, we investigate the effect of BH particle production/evaporation on two modes in the exterior region of the BH event horizon that are initially maximally entangled, when one mode falls inward and interacts with the black hole, and the other remains forever outside and non-interacting.

Paul M. Alsing

2015-02-04T23:59:59.000Z

453

Probing nanoscale photo-oxidation in organic films using spatial hole burning near-field scanning optical microscopy  

E-Print Network [OSTI]

Probing nanoscale photo-oxidation in organic films using spatial hole burning near-field scanning from a stationary NSOM tip to induce photo-oxidation. The reduction in the fluorescence yield resulting photo-oxidation as a function of time, position, and environment free from the limits of far

Buratto, Steve

454

Nekton community change along estuarine salinity gradients: Can salinity zones be defined?  

Science Journals Connector (OSTI)

Organisms tend to inhabit predictable portions of estuaries along salinity gradients between the ocean inlets (salinity > 35 psu) and the freshwater tributaries (salinity = 0). Previous studies have suggested ......

Marin F. D. Greenwood

2007-06-01T23:59:59.000Z

455

Species richness, diversity and density of understory vegetation along disturbance gradients in the Himalayan conifer forest  

Science Journals Connector (OSTI)

We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging (gap) and grazing (primarily by cattle) disturbance gradients, and sought to identify drivers...

Kesang Wangchuk; Andrs Darabant; Prem Bahadur Rai

2014-09-01T23:59:59.000Z

456

ACCRETION-JET CONNECTION IN BLACK HOLES THE ORIGIN OF STELLAR BLACK HOLES &  

E-Print Network [OSTI]

a very large kinetic energy...Moon @ >.9c" #12;POWERFUL DARK JETS FROM BLACK HOLES Radio (Dubner et al erg/sec · NON RADIATIVE JETS = "DARK" JETS · >50% OF THE ENERGY IS NOT RADIATED 1o = 60 pc1arcsec VLA Since their discovery there have been seven International workshops Compact binaries with jets #12

Maryland at College Park, University of

457

Towards a theory of ecotone resilience: Coastal vegetation on a salinity gradient  

Science Journals Connector (OSTI)

Ecotones represent locations where vegetation change is likely to occur as a result of climate and other environmental changes. Using a model of an ecotone vulnerable to such future changes, we estimated the resilience of the ecotone to disturbances. The specific ecotone is that between two different vegetation types, salinity-tolerant and salinity-intolerant, along a gradient in groundwater salinity. In the case studied, each vegetation type, through soil feedback loops, promoted local soil salinity levels that favor itself in competition with the other type. Bifurcation analysis was used to study the system of equations for the two vegetation types and soil salinity. Alternative stable equilibria, one for salinity-tolerant and one for salinity intolerant vegetation, were shown to exist over a region of the groundwater salinity gradient, bounded by two bifurcation points. This region was shown to depend sensitively on parameters such as the rate of upward infiltration of salinity from groundwater into the soil due to evaporation. We showed also that increasing diffusion rates of vegetation can lead to shrinkage of the range between the two bifurcation points. Sharp ecotones are typical of salt-tolerant vegetation (mangroves) near the coastline and salt-intolerant vegetation inland, even though the underlying elevation and groundwater salinity change very gradually. A disturbance such as an input of salinity to the soil from a storm surge could upset this stable boundary, leading to a regime shift of salinity-tolerant vegetation inland. We showed, however, that, for our model as least, a simple pulse disturbance would not be sufficient; the salinity would have to be held at a high level, as a press, for some time. The approach used here should be generalizable to study the resilience of a variety of ecotones to disturbances.

Jiang Jiang; Daozhou Gao; Donald L. DeAngelis

2012-01-01T23:59:59.000Z

458

Geodesic Study of Regular Hayward Black Hole  

E-Print Network [OSTI]

This paper is devoted to study the geodesic structure of regular Hayward black hole. The timelike and null geodesic have been studied explicitly for radial and non-radial motion. For timelike and null geodesic in radial motion there exists analytical solution, while for non-radial motion the effective potential has been plotted, which investigates the position and turning points of the particle. It has been found that massive particle moving along timelike geodesics path are dragged towards the BH and continues move around BH in particular orbits.

G. Abbas; U. Sabiullah

2014-06-03T23:59:59.000Z

459

CHARYBDIS: A Black hole event generator.  

E-Print Network [OSTI]

model of black hole production and decay which can be interfaced to existing Monte Carlo programs using the Les Houches accord [4]. The major new theoretical input to the generator is the inclusion of the recently calculated grey-body factors for black... ? TH geometric arguments show that ?l,m? ? (?rh)2 in any number of dimensions, which means that at high energies the shape of the spectrum is like that of a black body. However the low energy behaviour of the grey-body factors is spin-dependent and also...

Harris, Chris M; Richardson, P; Webber, Bryan R

460

Conformal Invariance of Black Hole Temperature  

E-Print Network [OSTI]

It is shown that the surface gravity and temperature of a stationary black hole are invariant under conformal transformations of the metric that are the identity at infinity. More precisely, we find a conformal invariant definition of the surface gravity of a conformal Killing horizon that agrees with the usual definition(s) for a true Killing horizon and is proportional to the temperature as defined by Hawking radiation. This result is reconciled with the intimate relation between the trace anomaly and the Hawking effect, despite the {\\it non}invariance of the trace anomaly under conformal transformations.

Ted Jacobson; Gungwon Kang

1993-07-06T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Down-hole periodic seismic generator  

DOE Patents [OSTI]

A down hole periodic seismic generator system is disclosed for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.

Hardee, H.C.; Hills, R.G.; Striker, R.P.

1982-10-28T23:59:59.000Z

462

Black Hole Constraints on Varying Fundamental Constants  

SciTech Connect (OSTI)

We apply the generalized second law of thermodynamics and derive upper limits on the variation in the fundamental constants. The maximum variation in the electronic charge permitted for black holes accreting and emitting in the present cosmic microwave background corresponds to a variation in the fine-structure constant of {delta}{alpha}/{alpha}{approx_equal}2x10{sup -23} per second. This value matches the variation measured by Webb et al. [Phys. Rev. Lett. 82, 884 (1999); Phys. Rev. Lett. 87, 091301 (2001)] using absorption lines in the spectra of distant quasars and suggests the variation mechanism may be a coupling between the electron and the cosmic photon background.

MacGibbon, Jane H. [Department of Physics and Chemistry, University of North Florida, Jacksonville, Florida 32224 (United States)

2007-08-10T23:59:59.000Z

463

The Fourth Law of Black Hole Thermodynamics  

E-Print Network [OSTI]

We show that black holes fulfill the scaling laws arising in critical transitions. In particular, we find that in the transition from negative to positive values the heat capacities $C_{JQ}$, $C_{\\Omega Q}$ and $C_{J\\Phi}$ give rise to critical exponents satisfying the scaling laws. The three transitions have the same critical exponents as predicted by the universality Hypothesis. We also briefly discuss the implications of this result with regards to the connections among gravitation, quantum mechanics and statistical physics.

C. O. Lousto

1993-06-10T23:59:59.000Z

464

Black Hole Remnants at the LHC  

E-Print Network [OSTI]

We investigate possible signatures of black hole events at the LHC in the hypothesis that such objects will not evaporate completely, but leave a stable remnant. For the purpose of defining a reference scenario, we have employed the publicly available Monte Carlo generator CHARYBDIS2, in which the remnant's behavior is mostly determined by kinematic constraints and conservation of some quantum numbers, such as the baryon charge. Our findings show that electrically neutral remnants are highly favored and a significantly larger amount of missing transverse momentum is to be expected with respect to the case of complete decay.

L. Bellagamba; R. Casadio; R. Di Sipio; V. Viventi

2012-01-16T23:59:59.000Z

465

Artificial neural network modelling and multi objective optimisation of hole drilling electro discharge micro machining of invar  

Science Journals Connector (OSTI)

Hole drilling electro discharge micro machining (HD-EDMM) is one of the potential method for creation of micro-holes in difficult to machine electrically conductive workpiece materials. Maintaining quality and accuracy of the drilled micro-holes along with better performance characteristics have always been a challenge for the researchers and manufacturers. Keeping cost and time of manufacturing into consideration, modelling and optimisation of EDMM is required. In this paper, attempts have been made to model the HD-EDMM process using feed forward back propagation neural network (BPNN) and further combined with GRA-based PCA for its optimisation. The developed ANN model and finally optimised results are validated with our own experimentally obtained results. The approach used in the present paper would be extendable to other configuration of EDMM such as milling-EDMM, wire-EDMM and grinding-EDMM.

Rajesh Kumar Porwal; Vinod Yadava; J. Ramkumar

2012-01-01T23:59:59.000Z

466

PHOTOCHEMICAL AND NON-PHOTOCHEMICAL HOLE BURNING IN DIMETHYL-S-TETRAZINE IN A POLYVINYL CARBAZOLE FILM  

SciTech Connect (OSTI)

Hole burning as well as fluorescence line narrowing experiments have been performed on the system dimethyl-s-tetrazine in polyvinyl carbazole films at low temperatures. The first singlet electronic absorption bands are typical (300 cm{sup -1} wide) of inhomogeneously broadened bands of guest molecules in amorphous organic hosts. Evidence is presented for both photochemical and non-photochemical hole burning. The narrowest holes observed were Lorentzian, had a width 0.44 cm{sup -1} at 1.8 K, and are believed to be of non-photochemical origin. A model which envisions the guest molecules to occupy different sites in the polymer host with a distribution of energy barriers between sites is used to describe these observations. The fast (20 psec) relaxation time implied by the 0,44 cm{sup -1} Lorentzian linewidth is interpreted as indicative of the rate of site interconversion in the excited state.

Cuellar, E.; Castro, G.

1980-05-01T23:59:59.000Z

467

Primordial black holes as biased tracers  

E-Print Network [OSTI]

Primordial black holes (PBHs) are theoretical black holes which may be formed during the radiation dominant era and, basically, caused by the gravitational collapse of radiational overdensities. It has been well known that in the context of the structure formation in our Universe such collapsed objects, e.g., halos/galaxies, could be considered as bias tracers of underlying matter fluctuations and the halo/galaxy bias has been studied well. Employing a peak-background split picture which is known to be a useful tool to discuss the halo bias, we consider the large scale clustering behavior of the PBH and propose an almost mass-independent constraint to the scenario that dark matters (DMs) consist of PBHs. We consider the case where the statistics of the primordial curvature perturbations is almost Gaussian, but with small local-type non-Gaussianity. If PBHs account for the DM abundance, such a large scale clustering of PBHs behaves as nothing but the matter isocurvature perturbation and constrained strictly by...

Tada, Yuichiro

2015-01-01T23:59:59.000Z

468

Electrical Generating Capacities of Geothermal Slim Holes  

SciTech Connect (OSTI)

Theoretical calculations are presented to estimate the electrical generating capacity of the hot fluids discharged from individual geothermal wells using small wellhead generating equipment over a wide range of reservoir and operating conditions. The purpose is to appraise the possibility of employing slim holes (instead of conventional production-size wells) to power such generators for remote off-grid applications such as rural electrification in developing countries. Frequently, the generating capacity desired is less than one megawatt, and can be as low as 100 kilowatts; if slim holes can be usefully employed, overall project costs will be significantly reduced. This report presents the final results of the study. Both self-discharging wells and wells equipped with downhole pumps (either of the ''lineshaft'' or the ''submersible'' type) are examined. Several power plant designs are considered, including conventional single-flash backpressure and condensing steam turbines, binary plants, double-flash steam plants, and steam turbine/binary hybrid designs. Well inside diameters from 75 mm to 300 mm are considered; well depths vary from 300 to 1200 meters. Reservoir temperatures from 100 C to 240 C are examined, as are a variety of reservoir pressures and CO2 contents and well productivity index values.

Pritchett, J.W.

1998-10-01T23:59:59.000Z

469

Thermodynamics of (2+1)-dimensional acoustic black hole based on the generalized uncertainty principle  

E-Print Network [OSTI]

We study thermodynamic quantities of an acoustic black hole and its thermodynamic stability in a cavity based on the generalized uncertainty principle. It can be shown that there is a minimal black hole which can be a stable remnant after black hole evaporation. Moreover, the behavior of the free energy shows that the large black hole is stable too. Therefore, the acoustic black hole can decay into the remnant or the large black hole.

Wontae Kim; Edwin J. Son; Myungseok Yoon

2008-01-09T23:59:59.000Z

470

Long term black hole evolution with the BSSN system by pseudospectral methods  

SciTech Connect (OSTI)

We present long term evolutions of a single black hole of mass M with the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) system using pseudospectral methods. For our simulations we use the SGRID code where the BSSN system is implemented in its standard second order in space form. Previously we found that such simulations are quite unstable. The main goal of this paper is to present two improvements which now allow us to evolve for longer times. The first improvement is related to the boundary conditions at the excised black hole interior. We now use a gauge condition that ensures that all modes are going into the black hole, so that no boundary conditions are needed at the excision surface. The second more significant improvement has to do with our particular numerical method and involves filters based on projecting the double Fourier expansions used for the angular dependence onto spherical harmonics. With these two improvements it is now easily possible to evolve for several thousand M. The only remaining limitation seems to be the radiative outer boundary conditions used here. Yet this problem can be ameliorated by pushing out the location of the outer boundary, which leads to even longer run times.

Tichy, Wolfgang [Department of Physics, Florida Atlantic University, Boca Raton, Florida 33431 (United States)

2009-11-15T23:59:59.000Z

471

Black hole radiation in the presence of a short distance cutoff  

Science Journals Connector (OSTI)

A derivation of the Hawking effect is given which avoids reference to field modes above some cutoff frequency ?c?M-1 in the free-fall frame of the black hole. To avoid reference to arbitrarily high frequencies, it is necessary to impose a boundary condition on the quantum field in a timelike region near the horizon, rather than on a (spacelike) Cauchy surface either outside the horizon or at early times before the horizon forms. Because of the nature of the horizon as an infinite redshift surface, the correct boundary condition at late times outside the horizon cannot be deduced, within the confines of a theory that applies only below the cutoff, from initial conditions prior to the formation of the hole. A boundary condition is formulated which leads to the Hawking effect in a cutoff theory. It is argued that it is possible the boundary condition is not satisfied, so that the spectrum of black hole radiation may be significantly different from that predicted by Hawking, even without the back reaction near the horizon becoming of order unity relative to the curvature.

Ted Jacobson

1993-07-15T23:59:59.000Z

472

Intermediate-Mass Black Holes as LISA Sources  

E-Print Network [OSTI]

Intermediate-mass black holes (IMBHs), with masses of hundreds to thousands of solar masses, will be unique sources of gravitational waves for LISA. Here we discuss their context as well as specific characteristics of IMBH-IMBH and IMBH-supermassive black hole mergers and how these would allow sensitive tests of the predictions of general relativity in strong gravity.

M. Coleman Miller

2008-12-16T23:59:59.000Z

473

Binary Black Hole Accretion Flows in Merged Galactic Nuclei  

Science Journals Connector (OSTI)

......for Theoretical Physics, Oiwake-cho...when the gas can pass across the maximum...mass-capture rates are eventually...holes|black hole physics|galaxies: nuclei...when the gas can pass across the maximum...mass-capture rates exhibit little...for Theoretical Physics (YITP) of Kyoto......

Kimitake Hayasaki; Shin Mineshige; Hiroshi Sudou

2007-04-25T23:59:59.000Z

474

Quasar evolution and the growth of black holes  

Science Journals Connector (OSTI)

......hole which accretes at a rate that is ultimately limited...intermittently at an average rate that is a universal function...that the mean accretion rate scales as M 1.5 t 6...sufficiently massive galaxies pass through a quasar phase...accretion discs|black hole physics|galaxies: active......

Todd A. Small; Roger D. Blandford

1992-12-15T23:59:59.000Z

475

Accelerating and rotating black holes J. B. Griffiths1  

E-Print Network [OSTI]

Accelerating and rotating black holes J. B. Griffiths1 and J. Podolsk´y2 1Department Abstract An exact solution of Einstein's equations which represents a pair of accelerating and rotating which explicitly contains the known special cases for either rotating or accelerating black holes

476

Evaluating an icon of population persistence: the Devil's Hole pupfish  

Science Journals Connector (OSTI)

...research-article Research articles 1001 60 197 Evaluating an icon of population persistence: the Devil's Hole pupfish J. Michael...Based on our analyses, we conclude that rather than being an icon of unusual persistence in isolation, the Devil's Hole pupfish...

2014-01-01T23:59:59.000Z

477

Synchronous Black Hole Search in Directed Graphs Adrian Kosowski  

E-Print Network [OSTI]

Synchronous Black Hole Search in Directed Graphs Adrian Kosowski Alfredo Navarra Cristina M called black hole nodes, and once a robot enters in one of them, it is destroyed. The goal is to find supported by the Italian CNR Short-Term Mobility Program. A. Kosowski was supported Polish Ministry Grant N

Paris-Sud XI, Université de

478

Modified Black Hole with Polar Jet and Vortex  

E-Print Network [OSTI]

There are many models relating an accretion disk of Black Hole to jet outflow. The herein heuristic model describes the continuation of an external accretion disk to an internal accretion disk for less than Black Hole horizon, and subsequent polar jet outflow along polar axis out of polar vortex wherein the event horizon is no longer descriptive.

T. Tmmalm

2001-12-06T23:59:59.000Z

479

Electromagnetic extraction of energy from Kerr black holes  

E-Print Network [OSTI]

We elucidate the `right' process for energy extraction from Kerr black holes through `FFDE' magnetospheres, free from causality violation. It is shown that the magnetosphere of a Kerr black hole possesses the double-structure, consisting of the inner and outer magnetospheres with the pair-creation gap between them and with respective unipolar batteries at the inner and outer surfaces of the gap.

Isao Okamoto

2005-06-14T23:59:59.000Z

480

Black holes at the IceCube neutrino telescope  

Science Journals Connector (OSTI)

If the fundamental Planck scale is about a TeV and the cosmic neutrino flux is at the Waxman-Bahcall level, quantum black holes are created daily in the Antarctic ice cap. We reexamine the prospects for observing such black holes with the IceCube neutrino-detection experiment. To this end, we first revise the black hole production rate by incorporating the effects of inelasticty, i.e., the energy radiated in gravitational waves by the multipole moments of the incoming shock waves. After that we study in detail the process of Hawking evaporation accounting for the black holes large momentum in the lab system. We derive the energy spectrum of the Planckian cloud which is swept forward with a large, O(106), Lorentz factor. (It is noteworthy that the boosted thermal spectrum is also relevant for the study of near-extremal supersymmetric black holes, which could be copiously produced at the Large Hadron Collider.) In the semiclassical regime, we estimate the average energy of the boosted particles to be less than 20% the energy of the ? progenitor. Armed with such a constraint, we determine the discovery reach of IceCube by tagging on soft (relative to what one would expect from charged current standard model processes) muons escaping the electromagnetic shower bubble produced by the black holes light descendants. The statistically significant 5? excess extends up to a quantum gravity scale ?1.3??TeV.

Luis A. Anchordoqui; Matthew M. Glenz; Leonard Parker

2007-01-09T23:59:59.000Z

Note: This page contains sample records for the topic "gradient holes time" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Instabilities of (near) extremal rotating black holes in higher dimensions  

E-Print Network [OSTI]

Recently, Durkee and Reall have conjectured a criterion for linear instability of rotating, extremal, asymptotically Minkowskian black holes in $d\\ge 4$ dimensions, such as the Myers-Perry black holes. They considered a certain elliptic operator, $\\cal A$, acting on symmetric traceless tensors intrinsic to the horizon. Based in part on numerical evidence, they suggested that if the lowest eigenvalue, $\\lambda$, of this operator is less than the critical value $-1/4$ ( called "effective BF-bound"), then the black hole is linearly unstable. In this paper, we prove their conjecture. Our proof uses a combination of methods such as (i) the "canonical energy method" of Hollands-Wald, (ii) algebraically special properties of the near horizon geometries associated with the black hole, and (iii) the structure of the (linearized) constraint equations. Our method of proof is also applicable to rotating, extremal asymptotically Anti-deSitter black holes. In that case, our methods show that "all" such black holes are unstable. Although we explicitly discuss in this paper only extremal black holes, we argue that our methods can be generalized straightforwardly to obtain the same results for "near" extremal black holes.

Stefan Hollands; Akihiro Ishibashi

2014-08-04T23:59:59.000Z

482

ESTIMATE OF THE TOTAL MECHANICAL FEEDBACK ENERGY FROM GALAXY CLUSTER-CENTERED BLACK HOLES: IMPLICATIONS FOR BLACK HOLE EVOLUTION, CLUSTER GAS FRACTION, AND ENTROPY  

SciTech Connect (OSTI)

The total feedback energy injected into hot gas in galaxy clusters by central black holes can be estimated by comparing the potential energy of observed cluster gas profiles with the potential energy of non-radiating, feedback-free hot gas atmospheres resulting from gravitational collapse in clusters of the same total mass. Feedback energy from cluster-centered black holes expands the cluster gas, lowering the gas-to-dark-matter mass ratio below the cosmic value. Feedback energy is unnecessarily delivered by radio-emitting jets to distant gas far beyond the cooling radius where the cooling time equals the cluster lifetime. For clusters of mass (4-11) x 10{sup 14} M{sub sun}, estimates of the total feedback energy, (1-3) x 10{sup 63} erg, far exceed feedback energies estimated from observations of X-ray cavities and shocks in the cluster gas, energies gained from supernovae, and energies lost from cluster gas by radiation. The time-averaged mean feedback luminosity is comparable to those of powerful quasars, implying that some significant fraction of this energy may arise from the spin of the black hole. The universal entropy profile in feedback-free gaseous atmospheres in Navarro-Frenk-White cluster halos can be recovered by multiplying the observed gas entropy profile of any relaxed cluster by a factor involving the gas fraction profile. While the feedback energy and associated mass outflow in the clusters we consider far exceed that necessary to stop cooling inflow, the time-averaged mass outflow at the cooling radius almost exactly balances the mass that cools within this radius, an essential condition to shut down cluster cooling flows.

Mathews, William G.; Guo Fulai, E-mail: mathews@ucolick.org [University of California Observatories/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2011-09-10T23:59:59.000Z

483

On a local formalism for time evolution of dynamical systems  

E-Print Network [OSTI]

The formalism of local maximization for entropy gradient producing the evolution and dynamical equations for closed systems. It eliminates the inconsistency between the reversibilty of time in dynamical equations and the strict direction of irreversible evolution for complex systems, causality contradictions and ambiguity of time flow in different systems. Independently it leads to basic principles of special relativity.

Drozdov, I V

2015-01-01T23:59:59.000Z

484

Graphene and the Zermelo Optical Metric of the BTZ Black Hole  

E-Print Network [OSTI]

It is well known that the low energy electron excitations of the curved graphene sheet $\\Sigma$ are solutions of the massless Dirac equation on a 2+1 dimensional ultra-static metric on ${\\Bbb R} \\times \\Sigma$. An externally applied electric field on the graphene sheet induces a gauge potential which could be mimicked by considering a stationary optical metric of the Zermelo form, which is conformal to the BTZ black hole when the sheet has a constant negative curvature. The Randers form of the metric can model a magnetic field, which is related by a boost to an electric one in the Zermelo frame. We also show that there is fundamental geometric obstacle to obtaining a model that extends all the way to the black hole horizon.

M. Cvetic; G. W. Gibbons

2012-02-14T23:59:59.000Z

485

E-Print Network 3.0 - access hole parameters Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

features in this regime whenever the quantum dot hole level is resonant with two... -dimensional hole states located at the capping layer-blocking barrier interface in our...

486

Slim Holes At Fort Bliss Area (DOE GTP) | Open Energy Information  

Open Energy Info (EERE)

Fort Bliss Area Exploration Technique Slim Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes 2 slim holes References (1 January 2011) GTP ARRA Spreadsheet...

487

Fuel injector Holes (Fabrication of Micro-Orifices for Fuel Injectors...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

injector Holes (Fabrication of Micro-Orifices for Fuel Injectors) Fuel injector Holes (Fabrication of Micro-Orifices for Fuel Injectors) 2009 DOE Hydrogen Program and Vehicle...

488

Hypervelocity binary stars: smoking gun of massive binary black holes  

E-Print Network [OSTI]

The hypervelocity stars recently found in the Galactic halo are expelled from the Galactic center through interactions between binary stars and the central massive black hole or between single stars and a hypothetical massive binary black hole. In this paper, we demonstrate that binary stars can be ejected out of the Galactic center with velocities up to 10^3 km/s, while preserving their integrity, through interactions with a massive binary black hole. Binary stars are unlikely to attain such high velocities via scattering by a single massive black hole or through any other mechanisms. Based on the above theoretical prediction, we propose a search for binary systems among the hypervelocity stars. Discovery of hypervelocity binary stars, even one, is a definitive evidence of the existence of a massive binary black hole in the Galactic center.

Youjun Lu; Qingjuan Yu; D. N. C. Lin

2007-07-12T23:59:59.000Z

489

Experimental Signature for Black Hole Production in Neutrino Air Showers  

E-Print Network [OSTI]

The existence of extra degrees of freedom beyond the electroweak scale may allow the formation of black holes in nearly horizontal neutrino air showers. In this paper we examine the average properties of the light descendants of these black holes. Our analysis indicates that black hole decay gives rise to deeply penetrating showers with an electromagnetic component which differs substantially from that in conventional neutrino interactions, allowing a good characterization of the phenomenon against background. Naturally occurring black holes in horizontal neutrino showers could be detected and studied with the Auger air shower array. Since the expected black hole production rate at Auger is $> 1$ event/year, this cosmic ray observatory could be potentially powerful in probing models with extra dimensions and TeV-scale gravity.

Luis Anchordoqui; Haim Goldberg

2001-10-15T23:59:59.000Z

490

Extremal black holes and the first law of thermodynamics  

Science Journals Connector (OSTI)

We study the low-temperature expansion of the first law of thermodynamics for near-extremal black holes. We show that for extremal black holes with nonvanishing entropy, the leading-order contribution yields an expression for their extremal entropy that is in agreement with the entropy-function result. When their entropy vanishes due to the vanishing of a one-cycle on the horizon, such a leading contribution is always compatible with the first law satisfied by a Baados-Teitelboim-Zanelli black hole. The universality of these results follows from universal facts about extremal black holes. Our results are consistent with both the presence of local AdS2 and AdS3 near-horizon throats for extremal black holes and with the suggested quantum microscopic descriptions (AdS2/CFT1, Kerr/CFT, and extremal vanishing horizon/CFT).

Maria Johnstone; M. M. Sheikh-Jabbari; Joan Simn; Hossein Yavartanoo

2013-11-27T23:59:59.000Z

491

Effects of pressure gradient on global Alfvn eigenmodes in reversed field pinch  

SciTech Connect (OSTI)

The effects of pressure gradient on the existence of global Alfvn eigenmodes (GAE) in Reversed Field Pinch are studied by numerical calculation. It is found that GAEs near the plasma core can exist when pressure gradient is sufficiently large. The calculated mode frequency and structure are consistent with the experimental results in the Madison Symmetric Torus.

Cai, Huishan, E-mail: hscai@mail.ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)] [CAS Key Laboratory of Geospace Environment, Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Fu, Guoyong, E-mail: fu@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lin, Liang; Ding, Weixing; Brower, D. L. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)] [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States); Liu, D. Y. [Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Hu, Y. J. [Institute of Plasma Physics, CAS (China)] [Institute of Plasma Physics, CAS (China)

2014-02-15T23:59:59.000Z

492

Quantification of the electrochemical proton gradient and activation of ATP synthase in leaves  

E-Print Network [OSTI]

Quantification of the electrochemical proton gradient and activation of ATP synthase in leaves Available online 12 April 2008 Keywords: ATP synthase Electrochemical proton gradient Membrane potential We of the ATP synthase (Junge, W., Rumberg, B. and Schröder, H., Eur. J. Biochem. 14 (1970) 575

493

Supercurrent-Induced Temperature Gradient across a Nonequilibrium SNS Josephson Junction M. S. Crosser,1  

E-Print Network [OSTI]

Supercurrent-Induced Temperature Gradient across a Nonequilibrium SNS Josephson Junction M. S direction. The feature represents an effective temperature gradient across the SNS Josephson junction Josephson junction (SNS JJ) into a `` junction'' by driving the electron energy distribution far from

Birge, Norman

494

Deformation-induced inverted metamorphic eld gradients: an example from the southeastern Canadian Cordillera  

E-Print Network [OSTI]

Deformation-induced inverted metamorphic ®eld gradients: an example from the southeastern Canadian allochthon and Monashee complex, exhibits an inverted metamorphic ®eld gradient. New data presented preserving evidence of strongly diachronous deformation and an apparent inverted metamorphism. # 1999

Gibson, Dan

495

Coal Ranks and Geothermal Gradients in High-volatile Bituminous Coalfields  

Science Journals Connector (OSTI)

... 380; Sw. No., 6. If it is assumed that no great changes in geothermal gradient have occurred since the early Pleistocene, this coal was metamorphosed at a temperature ... Silesia5. The most obvious explanation is that of a nearly two to one difference in geothermal gradient. Comparison of data from the Carboniferous coalfields of the Netherlands with analyses of ...

R. P. SUGGATE; J. O. ELPHICK

1964-07-04T23:59:59.000Z

496

High Efficiency in Energy Generation from Salinity Gradients with Reverse Electrodialysis  

Science Journals Connector (OSTI)

High Efficiency in Energy Generation from Salinity Gradients with Reverse Electrodialysis ... Reverse electrodialysis; Renewable energy; Efficiency; Entropy; Salinity gradient energy; Ion exchange membranes ... power from the sequential flow of fresh and saline water, without the need for auxiliary processes or converters. ...

David A. Vermaas; Joost Veerman; Ngai Yin Yip; Menachem Elimelech; Michel Saakes; Kitty Nijmeijer

2013-08-02T23:59:59.000Z

497

Thermodynamic, Energy Efficiency, and Power Density Analysis of Reverse Electrodialysis Power Generation with Natural Salinity Gradients  

Science Journals Connector (OSTI)

Thermodynamic, Energy Efficiency, and Power Density Analysis of Reverse Electrodialysis Power Generation with Natural Salinity Gradients ... solns. of different salinities. ... River mouths are potentially abundant locations for the exploitation of the clean and renewable salinity gradient energy (SGE) as here perpetually fresh water mixes with saline seawater. ...

Ngai Yin Yip; David A. Vermaas; Kitty Nijmeijer; Menachem Elimelech

2014-04-03T23:59:59.000Z